i      

Abstract  of  thesis  entitled  

 

“An evidence-based guideline of preoperative forced-air warming

in reducing inadvertent perioperative hypothermia

for patients undergoing general anesthesia”

Submitted by

Wong Hoi Ching

For the degree of Master of Nursing

at The University of Hong Kong

in July 2016

Inadvertent perioperative hypothermia (IPH) is a common problem for

patients undergoing general anesthesia (GA), which could lead to many detrimental

physiologic alternations and increase morbidity. A core body temperature of less than

36ºC in the perioperative period without deliberate planning is defined as IPH. It

might increase the incidence of complications including coagulopathy, postoperative

shivering, surgical site infection and healing problem. Studies have shown that

preoperative forced-air warming before GA helps prevent IPH mostly. In this thesis,

six studies about the innovation of preoperative forced-air warming to reduce IPH are

systematically reviewed and appraised critically. The results of the selected studies

are summarized and synthesized so as to develop an evidence-based guideline of the

use of preoperative forced-air warming for patient undergoing GA. In order to adopt

the guideline in the local clinical setting, the implementation potential of the proposed

  ii    

guideline including the transferability, feasibility and the cost-benefit ratio were

assessed. An implementation plan including communication process, pilot study plan

and evaluation plan were established in order to promote a smooth implementation of

the innovation. It is aimed that the introduction of the innovation can help to reduce

IPH and its subsequent complication so to improve patient safety and surgical

outcomes.

 

                             

  iii    

An evidence-based guideline of preoperative forced-air warming

in reducing inadvertent perioperative hypothermia

for patients undergoing general anesthesia

by

Wong Hoi Ching

BNurs (Hons) H.K.U., R.N.

A thesis submitted in partial fulfillment of the requirements for

The Degree of Master of Nursing

at The University of Hong Kong

July 2016  

  iv    

Declaration

I declare that this thesis represents my own work, except where due

acknowledgement is made, and that is has not been previously included in a thesis,

dissertation or report submitted to this University or to any other institution for a

degree, diploma or other qualifications.

Signed ___________________________________________

Wong Hoi Ching

                           

  v      

Acknowledgements

I would like to express my sincere gratitude to my dissertation supervisor, Dr.

Veronica Lam for her considerate understanding, guidance, encouragement, and

expert advices throughout the dissertation journey. She is very supportive and helpful.

It is my great pleasure to have Dr. Lam being the supervisor in my master course

study in The University of Hong Kong.

I would also like to thank my colleagues, friends and classmates for their

support and help during these two years of study.

Last but not the least, I have to thank my family and my husband for their

caring and support.

                         

  vi    

Table of Contents

Abstract ......................................................................................................................... i

Declaration .................................................................................................................. iv Acknowledgements ...................................................................................................... v

Table of Contents ........................................................................................................ vi List of Appendixes ...................................................................................................... ix

Abbreviations ............................................................................................................... x  CHAPTER 1: INTRODUCTION .............................................................................. 1  

Background -------------------------------------------------------------------------------------------- 1

Affirming Need ---------------------------------------------------------------------------------------- 2

Significance -------------------------------------------------------------------------------------------- 4

Objectives ---------------------------------------------------------------------------------------------- 6

Research Question ------------------------------------------------------------------------------------ 7

PICO ---------------------------------------------------------------------------------------------------- 7

CHAPTER 2: CRITICAL APPRAISAL .................................................................. 8  

Search Strategy --------------------------------------------------------------------------------------- 8

Inclusion Criteria ------------------------------------------------------------------------------------- 8

Exclusion Criteria ------------------------------------------------------------------------------------ 9

Appraisal Strategy ------------------------------------------------------------------------------------ 9

Search Results ----------------------------------------------------------------------------------------- 9

Data Extraction ------------------------------------------------------------------------------------- 10

Quality Assessment --------------------------------------------------------------------------------- 10

Research question ............................................................................................................ 11 Randomization method ................................................................................................... 11 Concealment method ....................................................................................................... 11 Blinding method .............................................................................................................. 12 Group’s similarity ........................................................................................................... 12 Study’s intervention ........................................................................................................ 13 Outcome measurement .................................................................................................... 13 Dropout rate ..................................................................................................................... 13 Intention to treat analysis ................................................................................................ 14 Generalizability ............................................................................................................... 14

  vii    

Bias .................................................................................................................................. 14 Effectiveness and applicability ........................................................................................ 15

 Summary --------------------------------------------------------------------------------------------- 15

Country of study .............................................................................................................. 15 Sample size ...................................................................................................................... 16 Patient’s characteristics ................................................................................................... 16 Type of surgery ............................................................................................................... 17 Intervention ..................................................................................................................... 17 Control ............................................................................................................................. 18 Outcome measures .......................................................................................................... 18 Results ............................................................................................................................. 19

 Synthesis ---------------------------------------------------------------------------------------------- 20

Target population ............................................................................................................ 20 Intervention ..................................................................................................................... 20 Outcomes ......................................................................................................................... 21

 Conclusion ------------------------------------------------------------------------------------------- 21

CHAPTER 3: IMPLEMENTATION POTENTIAL AND CLINICAL GUIDELINE .............................................................................................................. 22  

Transferability of Findings ----------------------------------------------------------------------- 22

Target setting ................................................................................................................... 22 Target population ............................................................................................................ 23 Philosophy of care ........................................................................................................... 23 Sufficiency of patients being benefited ........................................................................... 24 Time for implementation and evaluation ........................................................................ 24

 Feasibility -------------------------------------------------------------------------------------------- 25

Freedom to try ................................................................................................................. 25 Interference on current staff function .............................................................................. 25 Support from the administration and organization .......................................................... 26 Equipment and facilities .................................................................................................. 27

 Cost-Benefit Ratio ---------------------------------------------------------------------------------- 27

Potential risks of the innovation ...................................................................................... 28 Potential benefit of the innovation .................................................................................. 28 Risks of maintaining current practice .............................................................................. 29 Material costs of implementing the innovation ............................................................... 29 Nonmaterial benefit of implementing the innovation ..................................................... 30

 Evidence-Based Practice Guideline ------------------------------------------------------------- 31

CHAPTER 4: IMPLEMENTATION PLAN .......................................................... 32  

Communication Plan ------------------------------------------------------------------------------- 32

  viii    

Identifying the Stakeholders ............................................................................................ 32 Communication Process .................................................................................................. 33

 Pilot Study Plan ------------------------------------------------------------------------------------- 36

Timeframe ....................................................................................................................... 36 Implementation Plan ....................................................................................................... 37 Evaluation Plan of Pilot Study ........................................................................................ 38

 Evaluation Plan ------------------------------------------------------------------------------------- 38

Outcomes ......................................................................................................................... 39 Timeframe ....................................................................................................................... 39 Client ............................................................................................................................... 40 Data Analysis .................................................................................................................. 41

 Basis for Implementation ------------------------------------------------------------------------- 41

Conclusion .................................................................................................................. 42  Appendixes ................................................................................................................. 43  

Appendix I - PRISMA 2009 Flow Diagram --------------------------------------------------- 43

Appendix II - Table of Evidence ----------------------------------------------------------------- 44

Appendix III - Summary of Appraisal Results ----------------------------------------------- 47

Appendix IV - Summary of Costs of the Implementation of the Innovation ----------- 49

Appendix V - Evidence-Based Practice Guideline ------------------------------------------- 50

Appendix VI - Key to Evidence Statements and Grades of Recommendations -------- 55

Appendix VII - Questionnaire on Preoperative Forced-air Warming Application for

Nurses ----------------------------------------------------------------------------- 56

Appendix VIII - Timeframe of the Implementation and Evaluation of the Innovation

------------------------------------------------------------------------------------- 58

References .................................................................................................................. 59

  ix    

List of Appendixes

Appendix I PRISMA 2009 Flow Diagram

Appendix II Table of Evidence

Appendix III Summary of Appraisal Results

Appendix IV Summary of Costs of Implementation of the Innovation

Appendix V Evidence-Based Practice Guideline

Appendix VI Key to Evidence Statements and Grades of Recommendations

Appendix VII Questionnaire on Preoperative Forced-air Warming Application

for Nurses

Appendix VIII Timeframe of the Implementation and Evaluation of the

Innovation

                                     

  x      

Abbreviations

APN Advanced Practiced Nurse

ASA American Society of Anesthesiologists physical status classification

System

BMI Body Mass Index

DOM Department Operations Manager

ENT Ear, Nose & Throat

GA General Anesthesia

HKWC Hong Kong West Cluster

IPH Inadvertent Perioperative Hypothermia

OT Operating Theatre

PACU Post-Anesthesia Care Unit

RCT Randomized Controlled Trial

RN Registered Nurse

SD Standard Deviation

SIGN The Scottish Intercollegiate Guideline Network

WM Ward Manager

                   

 

  1  

CHAPTER 1: INTRODUCTION

Background

Inadvertent perioperative hypothermia (IPH) is common in patients

undergoing general anesthesia. A core body temperature of less than 36ºC in the

perioperative period, which is not resulted from deliberate planning, is defined as

inadvertent perioperative hypothermia. Core body temperature can be measured in the

pulmonary artery by invasive temperature measurement through the insertion of a

pulmonary artery catheter. For noninvasive core body temperature measurement, the

tympanic, esophageal, and nasopharyngeal temperature are also regarded as reliable

measurements. All these methods can provide a continuous temperature monitoring

during surgery.

Due to the cold environment in the operation theatre, convective heat loss

from the large exposed body surface area is one of the contributing factors for the

development of hypothermia. Besides, the large opened body cavity, use of cold

intravenous solutions and blood products during surgery also contribute to

hypothermia (Charles et al., 1998). Sessler (2000) stated that the intraoperative

hypothermia composes of a three-phase pattern (cited in Shin et al., 2015). During the

first hour of general anesthesia, there would be a rapid decrease in the core body

temperature due to the anesthetic-induced impairment of thermoregulation. This leads

to the inhibition of thermoregulatory vasoconstriction with resultant core-to-

peripheral thermal redistribution due to peripheral vasodilatation induced by

anesthetic drugs. The subsequent two to three hours would be a relatively slow and

linear decrease in the body temperature results from the thermal imbalance, in which

  2  

the heat loss exceeds the metabolic heat production. The reduction in metabolic heat

production is also an effect of anesthesia. In the third phase, the core body

temperature reaches a plateau that remains constant even for prolonged surgery due to

vasoconstriction induced by low body temperature. Certain populations are at higher

risk of developing hypothermia induced by the effect of anesthesia such as the elderly

patients and those with combined medical problems are more susceptible groups of

patients (Erdling & Johansson, 2015).

The consequences of hypothermia could lead to many detrimental physiologic

alterations and increase morbidity. Complications include decrease metabolic rate,

decrease cardiac output, metabolic acidosis, healing problems, postoperative shivering,

coagulation and platelet function abnormalities, surgical site infection, pressure ulcer

incidence levels and extended post-anesthetic recovery (Kumar, Wong, Melling, &

Leaper, 2005; Scott & Buckland, 2006). In addition, thermal discomfort reduces

patient satisfaction with surgical anesthesia (Kurz, 2008) and increase anxiety.

Therefore, patients’ perioperative body temperature should be maintained to prevent

the complications of hypothermia and to lower the costs of health service.

Affirming Need

The operating theatre nurse where I work has fifteen operation theatres. There

are averagely over 400 elective surgeries per month. Many of the surgeries are

ultramajor or major types that require for more than three to four hours operation time.

Some cases even last for more than eight hours. In the routine daily care, we provide

warm blanket to patients after admission to the operation theatre. During the

intraoperative period, the infusion fluids and blood products are warmed. Warming

mattress and/or forced-air warming blanket are provided to prevent hypothermia.

  3  

Nasopharyngeal and rectal temperature measurements are commonly used for

continuous core temperature monitoring. The theatre temperature was set to be around

20-22°C. However, from my observation, there are still more than half of the patients

experience hypothermia either intraoperative or on admission to the post-anesthesia

care unit (PACU). Those hypothermic patients are more likely to develop

hyperventilation, shivering and higher anxiety level (Hooven, 2011). This results in a

lengthy recovery stay to resume normothermia of the patients and hence increase

healthcare’s workload and decrease turnover ability of the recovery rooms. For some

neurosurgical and trauma patients, it requires an extra stay in the operation theatre

after the operation finished to warm up the patients to an acceptable temperature

before discharge to the recovery room or ward. It is also observed that hypothermic

patients required longer time to be reversed from general anesthesia. As the elective

surgery schedule is very tight in public hospital, the overtime of surgery may lead to

cancellation of scheduled cases. This on the other hand prolongs the surgery waiting

list and increase hospital cost as well.

Some studies recommend that prewarming of patients for about 10 to 20

minutes before general anesthesia mostly prevent perioperative hypothermia

(Andrzejowski, Hoyle, Eapen & Turnbull, 2008; Horn et al., 2012). Prewarming is

defined as actively warm the patients by forced-air warming device before anesthesia

starts. It helps to reduce the core-to-peripheral temperature gradient and increases the

total body heat content (Sessler, 2001). Intraoperative warming by thermal mattress

and forced-air warming device prevents patient’s heat loss from exceeding the heat

production intraoperative (Röder et al., 2011). However, without prewarming, these

measures fail to prevent the core temperature decrease during the first hour of general

anesthesia when redistribution hypothermia occurs (Ihn et al., 2008).

  4  

In our current clinical setting, prewarming is not a usual practice. There is

inconsistency in the knowledge of the effectiveness of prewarming before general

anesthesia to prevent perioperative hypothermia among the operative nurses. Some of

the nurses assumed that prewarming a patient before surgery would have a positive

effect on patient’s postoperative temperature while others felt that the efficacy of

prewarming is questionable and intraoperative warming is adequate to maintain

normothermia. Therefore to review the updated studies on the effect of preoperative

forced-air warming on perioperative hypothermia for patients undergoing general

anesthesia so as to promote an evidence-based practice for the operating theatre

nurses is necessary.

Previous systematic reviews have been done. The one done by Cheng, 2013

was mainly focus on the effect of prewarming on postoperative hypothermia.

However the intraoperative hypothermia is also significant for the change in

hemodynamics, coagulopathy and surgical site infection, etc. Besides, there is lack of

consensus in prewarming times, warming device and warming methods in previous

studies. At the same time, there is new evidence derived from updated studies that

have not been reviewed. Therefore, I would like to review the effect of preoperative

forced-air warming in reducing inadvertent perioperative hypothermia for patients

undergoing general anesthesia and develop evidence-based practice guideline to

integrate the updated evidence into our daily practice.

Significance

Patients undergoing general anesthesia are vulnerable to a perioperative

decrease in core temperature leading to inadvertent perioperative hypothermia. Study

suggested that 50% to 70% of all surgical patients experience IPH (Frank, Shir, Raja,

  5  

Fleisher & Beattie, 1994). It is one of the perioperative nurse's’ roles to optimize

patient care practices to maintain normothermia and prevent perioperative

hypothermia. As mentioned, hypothermia could leads to many complications. Several

randomized controlled trials noted that hypothermia increases the rate of infection

(Andrzejowski et al., 2008; Erdling & Johansson, 2015; Shin et al., 2015). Kurz,

Sessler, and Lenhardt (1996) found that a mean intraoperative core temperature (±

standard deviation [SD]) of 35.7°C ± 0.6°C had a 13% increased risk of infection

compared with a normothermic body temperature. Additionally, hypothermia has

been found to affect the pharmacokinetics of anesthetic medications and blood loss

during surgery, and to alter physico-biological dynamics (Hooven, 2011). Leslie,

Sessler, Bjorksten, and Moayeri (1995) found that propofol concentrations averaged

28% more at 34°C than at 37°C. It has been noted that the duration of the action of

muscle relaxants such as atracurium and vecuronium would be significantly

prolonged in the hypothermic groups (Leslie et al., 1995). A meta-analysis completed

by Rajagopalan, Mascha, Na, and Sessler (2008) concluded that hypothermia

significantly increases blood loss by approximately 16% and increases the risk of a

blood transfusion by approximately 22%. Hypothermia has also been noted to

increase hospital costs (Mahoney & Odom, 1999). Because normothermic patients

were found to have less adverse outcomes compared with hypothermic patients,

hospital-associated costs were less (Mahoney & Odom, 1999). Increased PACU

length of stay and increased hospital stay were also associated with hypothermia in

the perioperative setting (Andrzejowski et al., 2008). Various healthcare institutions

have published clinical guidelines across the country advocating the importance of

maintaining normothermia in the perioperative setting. In its guideline for preventing

surgical site infection, the Centers for Disease Control and Prevention noted that

  6  

preventing hypothermia reduces the risk of infection. In addition, the American

Society of Anesthesiologists recommends in its practice guidelines that normothermia

should be a goal during emergence and recovery from anesthesia. Moreover,

minimizing hypothermia in the perioperative setting can promote optimal health for

patients. Understanding hypothermia, its complications and effective prevention

measures in the perioperative period is significant for nurses who want to apply

evidence-based practice in clinical practice. It is also essential to plan effective

interventions that minimize or make it possible to prevent complications arising from

surgical anesthesia, with a view to patient safety, which is the main goal of

perioperative nursing.

Objectives

1) To perform systematic literature review on the effectiveness of pre-operative

forced-air warming in reducing inadvertent perioperative hypothermia for

patients undergoing general anesthesia.

2) To appraise the chosen studies critically, then summarize and synthesize the

results from the chosen studies.

3) To develop an evidence-based guideline of the use of preoperative forced-air

warming for patient undergoing general anesthesia.

4) To assess the implementation potential of the proposed guidelines in local

clinical setting.

5) To develop implementation and evaluation plans fro the proposed guidelines.

  7  

Research Question

Is preoperative forced-air warming effective in reducing inadvertent perioperative

hypothermia for patients undergoing general anesthesia?

PICO

Under the PICO framework, the population (P) is adult patients undergoing general

anesthesia. The Intervention (I) is preoperative forced-air warming before induction

of anesthesia for a certain period of time. The comparison (C) is current warming

method without preoperative forced-air warming. The Outcome (O) is to reduce the

incidence of inadvertent perioperative hypothermia.

  8  

CHAPTER 2: CRITICAL APPRAISAL

Search Strategy

A systematic literature searching was performed from August 2015 to

November 2015 through electronic databases, which includes Pubmed and Cochrane

Library. The keywords used were separated into two groups. “Prewarming”,

“preoperative warming” and “preoperative forced-air warming” are in one group

while “hypothermia” and “perioperative hypothermia” are in another group. The

keywords were searched separately and by using “or” within groups and using “and”

between groups in both databases. The same sets of keywords were used for searching

in Google Scholar Engine. A PRISMA flow diagram was used to structure the

literature searching and screening for selecting appropriate articles that are relevant to

the research question. Inclusion and exclusion criteria were used to narrow down the

number of searched articles. After that, a manual searching of the reference list of

chosen studies was performed to prevent any missing of eligible literatures. Searching

for relevant literature reviews have also been done to check for any updated reviews

and identified the need of this guideline.

Inclusion Criteria

1. Adult patients ≥ 18 years old

2. Preoperative forced-air warming was used as an intervention

3. The incidence of perioperative hypothermia or the change in core temperature

is included in the outcome measures

4. Randomized controlled trial (RCT) studies

  9  

5. Articles published from 2005 to 2015

6. Written in English

7. Full text of articles is available

Exclusion Criteria

1. Patients undergoing regional anesthesia without general anesthesia

2. Use of other prewaming methods as the intervention

Appraisal Strategy

The Scottish Intercollegiate Guideline Network (SIGN) (2015) Methodology

Checklist 2 for controlled trials was used as a tool to critically appraise the internal

validity and the overall quality assessment of the selected studies. The results are

summarized in Appendix III, whereas the details are mentioned in the following

quality assessment.

Search Results

Under the criteria of randomized controlled trial studies published from 2005

to 2015 and written in English, the search results from the two electronic databases

are as follows. By using the keywords of “prewarming” OR “preoperative warming”

OR “preoperative forced air warming”, 28 articles in Pubmed and 81 articles in

Cochrane Library were found. By using the keywords of “hypothermia” OR

“perioperative hypothermia”, 475 articles in Pubmed and 973 articles in Cochrane

Library were found. By combining the two groups of keywords using “AND” for

  10  

searching, 15 articles in Pubmed and 32 articles in Cochrane Library were found. The

same sets of keywords were searched in Google Scholar Engine and 24 articles were

found. After checking for duplication, 39 articles were removed. Abstract screening

of the 32 articles left for the criteria of patients under general anesthesia and taking

preoperative forced-air warming as an intervention, 23 articles are removed for

irrelevance. Among the 9 remaining articles, 2 articles were removed due to full text

not available. 1 article was removed, as the study was not comparing the intervention

with control group, instead comparing two protocols of interventions. The 6

remaining full-text articles were assessed to be eligible for the review. The search

results were summarized in the PRISMA flow diagram shown in Appendix I.

Data Extraction

The 6 selected articles were reviewed in details. Data was extracted, integrated

and summarized in a table of evidence shown in Appendix II. The table of evidence

consisted of type of study design, patient’s characteristic, study intervention,

comparison, outcome measures, measuring tools, site and time interval for body

temperature, and results. Details were shown in the table of evidence.

Quality Assessment

The 6 selected articles were appraised under the following aspects under the

SIGN methodology checklist for controlled trials.

  11  

Research question

All the studies have addressed an appropriate and clearly focused question

with identified population, intervention, comparison and outcomes (Andrzejowski et

al., 2008; Erdling & Johansson, 2015; Fettes, Mulvaine, & Doren, 2013; Horn et al.,

2012; Kim et al., 2006; Shin et al., 2015).

Randomization method

For the study design, four of the studies used parallel-group RCT design

(Andrzejowski et al., 2008; Erdling & Johansson, 2015; Horn et al., 2012; Kim et al.,

2006). One used prospective pretest/posttest design (Fettes et al., 2013), while another

one used consecutive prospective design (Shin et al., 2015).

Three of the studies mentioned the randomization methods. One used

computer-generated randomization (Andrzejowski et al., 2008), another one used the

last two digits of patients account number and random integers for randomization

(Fettes et al., 2013), while the third one randomized by rolling a modified dice with

four faces representing four treatment groups (Horn et al., 2012). The other three

studies have mentioned about random assignment but have not specified the method

used (Erdling & Johansson, 2015; Kim et al., 2006; Shin et al., 2015).

Concealment method

Four of the studies used the sealed envelope technique for concealment

(Erdling & Johansson, 2015; Fettes et al., 2013; Kim et al., 2006; Shin et al., 2015),

while the other two studies have not addressed the concealment methods

(Andrzejowski et al., 2008; Horn et al, 2012).

  12  

Blinding method

Blinding to the subjects was not used in all the studies and the patients could

be easily noted for the provision of intervention, thus blinding was not applicable

(Andrzejowski et al., 2008; Erdling & Johansson, 2015; Fettes et al., 2013; Horn et

al., 2012; Kim et al., 2006; Shin et al., 2015). In Fettes et al., (2013)’s study, the

PACU nurses performing the postoperative temperature measurement were blinded to

patient’s group assignment. In Horn et al. (2012)’s study, the anesthetist providing

general anesthesia was blinded to the prewarming randomization and the investigator

in PACU grading patient’s shivering was blinded to patient’s core temperature and

the group assignment. Other four studies have not mentioned about any blinding to

the investigators intraoperative and postoperative (Andrzejowski et al., 2008; Erdling

& Johansson, 2015; Kim et al., 206; Shin et al., 2015).

Group’s similarity

There was no significant difference between the intervention and control

groups for patient’s characteristics, types and duration of surgery, theatre room

temperature, and anesthetic technique in five studies (Andrzejowski et al., 2008;

Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006;

Shin et al., 2015). As the impact of age and body mass index on core temperature was

also investigated in Erdling and Johansson (2015)’s study, these two patient’s

characteristics may differ between groups while the others variables were similar.

  13  

Study’s intervention

In five studies done by Andrzejowski et al. (2008), Erdling and Johansson

(2015), Fettes et al. (2013), Kim et al. (2006), and Shin et al. (2015), preoperative

forced air warming was the only difference between the intervention and control

groups. The study done by Horn et al. (2012) consisted of three intervention groups

with different duration of prewarming period. It aimed to investigate the effect of

short time periods of prewarming on the prevention of perioperative hypothermia.

Therefore the prewarming duration between groups was different.

Outcome measurement

All studies used valid and reliable measuring tools for the outcome

measurement (Andrzejowski et al., 2008; Erdling & Johansson, 2015; Fettes et al.,

2013; Horn et al., 2012; Kim et al., 2006; Shin et al., 2015). Esophageal and

nasopharyngeal temperature probes, temporal artery scanner, tympanic temperature

sensor and pulmonary artery catheter were used in the studies for measuring the core

temperature, in which all are valid and reliable. Some studies used more than one of

the above measuring tools (Andrzejowski et al., 2008; Erdling & Johansson, 2015;

Shin et al., 2015).

Dropout rate

Four studies done by Andrzejowski et al. (2008), Horn et al. (2012), Kim et al.

(2006), and Shin et al. (2015) reported 0% dropout rate. The other two studies done

by Erdling and Johansson (2015), and Fettes et al. (2013) reported 17% and 12%

dropout rate respectively. According to the notes on the use of SIGN methodology

  14  

checklist for randomized controlled trials, a dropout rate of less than 20% is regarded

as acceptable (SIGN, 2015).

Intention to treat analysis

Four studies done by Andrzejowski et al. (2008), Horn et al. (2012), Kim et al.

(2006), and Shin et al. (2015) have analysed the patients in the groups they were

randomly allocated. Studies done by Erdling and Johansson (2015), and Fettes et al.

(2013) only analysed the patients who completed the studies and based on patients

whom the outcome measures were obtained. In Fettes et al. (2013)’s study, five

patients in the intervention group withdrew before or shortly after the intervention due

to uncomfortable warming. The data of these patients was not included in the final

results analysis.

Generalizability

All the studies were carried out at one site (Andrzejowski et al., 2008; Erdling

& Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006; Shin et al.,

2015). Therefore the generalizability is limited.

Bias

According to the coding system of SIGN (2015), the quality of the studies in

minimizing bias can be rated as (++), (+), (-) and 0, which representing high quality,

acceptable, low quality and unacceptable respectively. Among the six studies, four are

rated as (++) as good randomization and group allocation concealment has been

achieved (Andrzejowski et al., 2008; Horn et al., 2012; Kim et al., 2006; Shin et al.,

  15  

2015). Study done by Erdling and Johansson (2015) is rated as (+) since the

concealment method was not mentioned. Fettes et al. (2013)’s study is rated as (-)

since the concealment method was not mentioned, not all the patients were analysed

in the groups that they were randomly allocated and increased attention has place on

intraoperative care to minimize heat loss on the need to keep patients warm.

Effectiveness and applicability

All the studied have taken the statistical power to be 80% and a significance

level of 5% for data analysis except the study of Kim et al. (2006), in which the

statistical power was not mentioned (Andrzejowski et al., 2008; Erdling & Johansson,

2015; Fettes et al., 2013; Horn et al., 2012; Shin et al., 2015). After evaluation of the

methodology used and the power of the studies, it is quite certain that the overall

effect of most of the selected studies is due to the prewarming intervention except

Fettes et al. (2013)’s study. Due to the difference in the group sample size, the

statistical outcome might be affected. The results of all the studies are directly

applicable to the target population in this guideline (Andrzejowski et al., 2008;

Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006;

Shin et al., 2015).

Summary

Country of study

The studies were carried out in United Kingdom, Sweden, American,

Germany, and two from South Korea (Andrzejowski et al., 2008; Erdling &

  16  

Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006; Shin et al.,

2015).

Sample size

The sample size of the studies ranged from 40 subjects (Kim et al., 2006) to

128 subjects (Fettes et al., 2013).

Patient’s characteristics

All studies include adult patients undergoing general anesthesia as the

subjects. Four studies included patients with American Society of Anesthesiologists

physical status classification system (ASA) < 3 only (Andrzejowski et al., 2008;

Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012), while the other two

studies did not mention the ASA status (Kim et al., 2006; Shin et al., 2015). Exclusion

criteria include peripheral vascular disease, history of fever, thyroid disease, unable to

understand information and give consent were used in three studies (Erdling &

Johansson, 2015; Fettes et al., 2013; Kim et al 2006; Shin et al., 2015). Patients with

neurological disease and known infection were excluded in two studies (Fettes et al.,

2013; Kim et al 2006; Shin et al., 2015). Erdling and Johansson (2015) excluded

patients with nasal or esophageal anomalies. Fettes et al. (2013) excluded patients

with autonomic dysfunctions, Cushing syndrome and with admission temperature

higher than 37.5 or less than 36.5. Kim et al. (2006) excluded patients with any skin

lesion, history of hypersensitivity to skin contact device, having reduced left

ventricular function and single coronary artery disease. Shin et al. (2015) exclude

patients with body mass index (BMI) exceeding 35 kg/m2 and preoperative body

  17  

temperature more that 37.2°C. Exclusion criteria was not mentioned in Andrzejowski

et al. (2008)’s study.

Type of surgery

Three studies recruited patients from scheduled surgeries, which includes

spinal surgery, colorectal surgery, general surgery, minor orthopedic surgeries and

ENT surgery (Andrzejowski et al., 2008; Erdling & Johansson, 2015; Horn et al.,

2012). Shin et al. (2015) included patients undergoing endovascular coiling to treat

cerebral aneurysm from both scheduled and emergency cases. Fettes et al. (2013)

recruited patients from various types of surgery while Kim et al. (2006) recruited

patients undergoing Off-pump coronary artery bypass surgery. Both haven’t

mentioned about whether the surgery was under scheduled only or included

emergency. The duration of surgery ranged from 40 min (Andrzejowski et al., 2008)

to over 210 min (Erdling & Johansson, 2015). The surgery duration was not

mentioned in Fettes et al. (2013)’s study.

Intervention

All the studied used forced-air warming blanket for preoperative warming

with the temperature setting ranged from 37.8°C (Fettes et al., 2013) to 44°C (Horn et

al., 2012). The mean duration of prewarming ranged from 30 min (Shin et al., 2015)

to 72 min (Andrzejowski et al., 2008), while Horn et al. (2012) studied on three

intervention groups with difference prewarming duration 10 min, 20 min, and 30 min.

  18  

Control

Warm cotton blanket was used in control group in three studies (Fettes et al.,

2013; Kim et al., 2006; Shin et al., 2015). Two studies covered patients in control

group with the forced-air warming blanket without turning on (Andrzejowski et al.,

2008; Fettes et al., 2013). Other studies just mentioned about passive insulation or

without prewarming in the control group (Erdling & Johansson, 2015; Horn et al.,

2012).

Outcome measures

Four studies measured the change in mean core temperature between

intervention and control groups intraoperative (Andrzejowski et al., 2008; Erdling &

Johansson, 2015; Kim et al., 2006; Shin et al., 2015). Two studies measured the

incidence of intraoperative hypothermia (Andrzejowski et al., 2008; Shin et al., 2015).

One study measured postoperative temperature (Fettes et al., 2013), and one measured

the incidence of postoperative hypothermia (Horn et al., 2012). Three studies

measured the number of patient experienced shivering in PACU (Andrzejowski et al.,

2008; Horn et al., 2012; Shin et al., 2015). Erdling and Johansson (2015) measured

the relationship of age and BMI between esophageal temperatures, while Fettes et al.

(2013) measured the length of PACU stay. Horn et al. (2012) measured the number of

patients required active warming intraoperative and postoperative. Kim et al. (2006)

measured the hemodynamic changes between groups intraoperative and Shin et al.

(2015) measured the number of patient developed procedure-related complication.

  19  

Results

For the measurement of mean core temperature between pre-warmed group

and control group, all the four studies showed that the core temperature in the pre-

warmed group was significantly greater than that in the control group (Andrzejowski

et al., 2008; Erdling & Johansson, 2015; Kim et al., 2006; Shin et al., 2015). For the

incidence of intraoperative hypothermia, both studies of Andrzejowski et al. (2008)

and Shin et al. (2015) showed a statistically significant lower incidence in the pre-

warmed group than the control group. Horn et al. (2012)’s study also reported a

significant lower incidence of postoperative hypothermia, lower necessity and shorter

duration for intra- and postoperative warming in the pre-warmed groups. Fettes et al.

(2013)’s study showed no significant difference in patient’s postoperative temperature

among group. However, the outcome might be affect by the difference in group size

and the lack of patients with hypothermia in both groups. Study of Erdling and

Johansson (2015) showed a negative correlation between esophageal temperature and

age, and a significant difference between BMI and esophageal temperature. This

indicates that the elderly are more likely to develop perioperative hypothermia and the

risk is reduced in the obese. Other measuring outcomes include postoperative

shivering, length of PACU stay, hemodynamic changes and procedure-related

complication were shown to have no significant difference among the pre-warmed

and control groups.

  20  

Synthesis

Target population

All the studies were carried out in developing countries with similar hospital

setting to the operation rooms in my working hospital (Andrzejowski et al., 2008;

Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006;

Shin et al., 2015). Majority of the patients studied were adults with ASA < 3

undergoing general anesthesia for elective surgery. Similar exclusion criteria were

reported from majority of the studies, which implied that our target population should

exclude those with fever, known infection, thyroid disease, peripheral vascular

disease and neurological disease.

Intervention

All the studies used forced-air warming device to provide the prewaming

intervention (Andrzejowski et al., 2008; Erdling & Johansson, 2015; Fettes et al.,

2013; Horn et al., 2012; Kim et al., 2006; Shin et al., 2015). Among the six studies,

half of them set the temperature of the forced-air warming at about 38°C, while

another half set the temperature ≥ 40°C. Since more significant results obtained from

studies with the set temperature ≥ 40°C, it implied that the temperature of the forced-

air warming device was better to be set as ≥ 40°C. Besides, majority of the studies

prewamed the patient ≥ 30 min. It implied that more than 30 min of prewaming would

be more effective to prevent perioperative redistribution hypothermia.

  21  

Outcomes

Majority of the studies measured patient’s mean core temperature of

intraoperative and showed significant difference between the intervention and control

group (Andrzejowski et al., 2008; Erdling & Johansson, 2015; Kim et al., 2006; Shin

et al., 2015). Half of the studies measured the incidence of hypothermia either

intraoperative or postoperative and showed significant results. Majority of the studies

showed no significant difference for other measuring outcomes. These implied that

the intraoperative mean core temperature and the incidence of hypothermia were best

to be used as the outcome measures for evaluating the effectiveness of preoperative

forced-air warming on patients undergoing general anesthesia.

Conclusion

After critical appraisal and evidence extraction from the selected articles, there

is adequate evidence in supporting the use of preoperative forced-air warming on

adult patient undergoing general anesthesia. Five out of the six studies showed

supports to the use of prewarming in reducing the decrease in mean core temperature

intraoperative and the incidence of perioperative hypothermia for patients undergoing

general anesthesia.

                       

  22  

CHAPTER 3: IMPLEMENTATION POTENTIAL

AND CLINICAL GUIDELINE

The previous chapters have shown that the provision of preoperative forced-

air warming was effective in reducing inadvertent perioperative hypothermia for

patients undergoing general anesthesia (GA). In order to translate the finding into

current clinical practice, this chapter reviews the implementation potential of this

evidence-based innovation through exploring the transferability of findings, feasibility

and cost-benefit ratio.

Transferability of Findings

The transferability of findings is assessed as followed by investigating the

similarity of the research findings with the current clinical aspects, including target

setting, population, philosophy of care, sufficiency of patients being benefit from the

innovation and the time of implementation and evaluation.

Target setting

The innovation of providing preoperative forced-air warming to patient

undergoing GA will be carried out in the operating theatres with 24-hour service in a

public hospital in Hong Kong West Cluster (HKWC). From the studies reviewed, all

were carried out in developing countries, which have similar operating theatre setting

and staff workload with Hong Kong (Andrzejowski, Hoyle, Eapen & Turnbull, 2008;

Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012; Kim et al., 2006;

Shin et al., 2015). The studies also covered various types of surgery, in which the

  23  

target operating theatres also perform various types of surgery. Thus the innovation is

transferable to be implemented in the proposed setting.

Target population

Majority of the reviewed studies included adult patients aged from 18 to 85

years old with American Society of Anesthesiologists physical status classification

system (ASA) < 3 undergoing GA (Andrzejowski et al., 2008; Erdling & Johansson,

2015; Fettes et al., 2013; Horn et al., 2012; Shin et al., 2015). In the target operating

rooms, about 75% of patients admitted for scheduled operation undergoing GA in

2015 were adults aged over 18 years old with ASA < 3 under an observational

estimation. Thus the characteristics of the target population are similar to those in the

studies.

Philosophy of care

The philosophy of care underlying the innovation which is to enhance patient

care and improve patient outcome fit the mission of the target hospital, which is “ to

care with Empathy, to serve with Expertise and Excellence”. By putting ourselves

into patient’s shoes, we empathize patient’s suffering from perioperative hypothermia

and the subsequent complications. For the excellence of care, introduction of the

innovation improves patient safety by minimizing the complications arise from

perioperative hypothermia. Besides, establishing an evidence-based guideline for the

innovation from the research findings helps to improve nursing care and enhance

nursing professionalism as well as achieving the expertise of care. As a result, the

prevailing philosophy is entrenched.

  24  

Sufficiency of patients being benefited

In the target hospital, there are averagely 4800 elective surgeries undergoing

general anesthesia per year, in which 3600 of them are adult patient over 18 years old

with ASA < 3 annually. As the hospital is a tertiary and quaternary referral centre for

many advanced and complex service including transplant, oral maxillofacial surgery,

reconstruction surgery and neurosurgery etc. in Hong Kong, the number of surgeries

is foresaw to be increasing. Therefore, the number of patients being benefited from

the innovation will be increased as well. It is estimated to have about 300 patients

being benefit per month.

Time for implementation and evaluation

It is estimated that the implementation and evaluation of the whole project will

take a period of 44 weeks. It will be divided into four phases including preparation,

pilot test, implementation and evaluation phases. During the preparatory phase, a

work group will be formed within the first week, which will be responsible for

planning, implementing and evaluating the whole project. 8 weeks will be reserved

for inter-departmental and interdisciplinary communication and coordination as well

as the preparation of required device and materials, guidelines and documentation

chart. 2 weeks will be taken for providing staff briefing sessions. After that, a pilot

test will commence for 6 weeks with evaluation. Subsequently, a 24-week

implementation phase will begin and followed with a 4-week evaluation phase.

  25  

Feasibility

The feasibility of implementing the innovation in the target setting is assessed

in the following section through different aspects.

Freedom to try

Perioperative nurses have the responsibility to ensure patients’ safety and to

minimize the risks and complications arising from general anesthesia and the surgery.

As the provision of preoperative forced-air warming requires no specific technique

and medication, nurses have the freedom to initiate, terminate and resume the

innovation according to patient’s condition after assessment. Nurses in the operating

theatres act as patients’ advocates are always encouraged to carry out high standards

of perioperative nursing care that are supported by evidence-based nursing practice.

Thus nurses in the operation theatres are highly encouraged to implement new

innovations.

Interference on current staff function

The innovation will cause minimal interference on current staff work. In our

current practice, nurses would notify the ward to send the next patient to the operating

room when the current surgery is finishing. When carrying out the innovation, nurses

have to send the case earlier in order to allow enough time for preoperative warming.

This actually facilitates nurses’ workflow. After sending the case, the circulating

nurse can start to perform counting with the scrub nurse, prepare dressing and

documentation when the operation is going to be finished. Sending the next patient in

advance help to relieve nurses’ workload during this busiest period. After admission

  26  

to the operating room, nurses routinely help patient loosen their gown and provide

some warmed blankets. The application of forced-air blanket for preoperative

warming can be carried out at the same time. Nurses just have to take one to two

minutes checking the patient’s body temperature and the presence of any

contraindications for preoperative warming before carrying out the innovation. The

whole procedure takes less than five minutes and is very easy and not time-consuming.

It is also a familiar procedure for nurses in the operation theatres as we do provide

intraoperative forced-air warming. Thus the interference on current staff functions is

minimal. Instead of releasing nurses from the current practice to implement the

innovation, nurses can integrate the innovation to the current nursing care and this

may facilitate their work as well.

Support from the administration and organization

The administration is expected to support the innovation as new practices are

always welcomed for enhancing patients’ benefit. For example, the department

adopted the project of colorful wall painting in admission area of the operating rooms

in order to attract pediatric patients’ attention and to lower their anxiety for the

operation. The project has gain good support from the administration and organization.

As promoting perioperative normothermia is one of the goals in our department this

year and the implementation of evidence-based practice is being addressed by our

Department Operations Manager (DOM), the organizational climate is conducive to

research utilization on this issue.

Besides, there is a fair degree of consensus among the nurses that the

innovation could be beneficial as we always apply forced-air warming to patients if

they were hypothermia during the intra- or postoperative periods. For testing the

  27  

innovation as a preventive measure preoperatively, the staff and the administrators are

expected to give welcome and support. Besides nurses, both the anesthetists and

surgeons are likely to support the innovation as the presence of perioperative

hypothermia leads to many complications that challenge their works and result in

poorer patient outcome. Therefore, it is unlikely to have friction or resistance within

the organization as well as from other departments for the implementation of the

innovation.

Equipment and facilities

The innovation will be carried out in the induction rooms in the operating

theatres, which is an existing waiting area for patient before general anesthesia. The

forced-air warming device and blanket are available in the organization but more

number of devices and blankets have to be purchased to meet the increase in usage.

The device will be cleaned after every use and the cleansing agent is available in the

operating theatres. The full-body forced-air blanket will be kept in the induction room

and discarded when broken or dirty. Tympanic thermometer and temperature probe

are required for assessment before the innovation and evaluation of the innovation,

which are all available in the department.

Cost-Benefit Ratio

Before implementing the innovation, the potential risks, benefits, material and

nonmaterial costs of the innovation have to be considered.

  28  

Potential risks of the innovation

Both Andrzejowski et al (2008) and Kim et al (2006) mentioned about the

potential risk of the innovation were thermal discomfort and perspiration complained

by patients if preoperative warming is continued for too long and the warming

temperature is set high. Besides, some patients with sensitive skin may have the risk

to develop rash after applying the forced-air blanket. Therefore, an optimal duration

and temperature of preoperative warming should be recommended from evidence.

Continuous monitoring on patients body temperature and observation for any patient

discomfort should be ensured.

Potential benefit of the innovation

By providing preoperative forced-air warming, the incidence of perioperative

hypothermia for patients undergoing GA will be reduced by about 25-50%

(Andrzejowski et al., 2008; Horn et al., 2012). This helps to minimize the

complications arise from hypothermia, which include decrease metabolic rate,

coagulopathy, extended reversal from GA and lengthy recovery stay, postoperative

shivering, increase in surgical site infection and wound healing problems (Kumar,

Wong, Melling, & Leaper, 2005; Scott & Buckland, 2006). Thus patient safety will be

improved and better patient outcome will be achieved. Besides, the provision of warm

may relieve patients’ anxiety level for undergoing GA and the surgery, in addition

improve patient’s satisfaction of the perioperative journey (Wagner, Byrne & Kolcoba,

2006). Shorten the period of reversal from GA helps with the efficiency of theatre

turnover, therefore less cancellation of operation may be resulted. The decrease length

of PACU stay also helps relieve nurses’ workload.

  29  

Risks of maintaining current practice

Without implementation of the innovation, the incidence of perioperative

hypothermia may remain high. The coagulation and platelet dysfunction arise from

hypothermia may lead to increase in blood loss during the surgery and pose more

challenges to the surgical team and extend the operation time. Patient with

hypothermia have a higher chance of developing postoperative shivering,

hyperventilation and increased anxiety level (Horn et al., 2012). The complications of

hypothermia also increase morbidity, surgical site infection and healing problems.

These also lead to prolong hospital stay and increase medical burden of the hospital.

Material costs of implementing the innovation

The material costs include the forced-air warming device, the full body

forced-air blanket, the photocopying of guidelines and the assessment and evaluation

forms. Each warming device cost HK$14,800 and each full-body blanket cost HK$75.

Photocopying of document cost HK$0.3 per page.

For the set up cost, 10 forced-air warming devices have to be purchased to

meet the increase in the usage demand for 15 operation theatres, as there are some

existing extra devices in the department. The full-body blanket will be wrapped in a

cotton blanket and will not touch the patients directly. The cotton blanket will be

changed after every use while the forced-air blanket can be reused. 60 forced-air

blankets have to be purchased for the first set up. The cost of photocopying of the

documents required will also be calculated and the details are shown in Appendix IV.

Together the total set up material cost is estimated to be HK$152,518.

The running cost will be mainly for the purchase of full-body forced-air

blanket and the photocopying of the assessment and evaluation forms. Each blanket

  30  

will be used for a week in one theatre. Thus, we estimate to purchase 60 forced-air

blankets in total for 15 theatres per month. Each patient requires a page of assessment

and evaluation form. As mentioned before, there are about 300 eligible patients per

month. Therefore taking 3600 eligible patients per year, the running cost will be about

HK$55,080 per year. Details of the calculation were shown in Appendix IV.

Other material cost of implementing the innovation will be the manpower and

venue. Two identical briefing sessions last for about 30 min will be provided for 120

registered nurses (RN) in the operation theatre. Each RN is required to attend once.

According to the pay scale of RN, the average salary of a nurse is estimated to be

HK$180 per hour. The venue, the computer system and projector are available in the

department and are free of charge. Thus the total nonmaterial cost of the innovation

will be HK$10,800. Details of the calculation were shown in Appendix IV.

Nonmaterial benefit of implementing the innovation

After implementing the innovation, the incidence of perioperative

hypothermia is expected to reduce. The improvement in patient safety and the

increase in effectiveness of nursing care improve staff morale and help reduce staff

workload. The decrease in complications help saving extra medical cost spending on

treating surgical site infection, healing problems as well as other morbidities. Shorten

the hospital stay lower the hospital cost as well.

To conclude, although the set up cost and the running cost of implementing

the innovation are quite high, it is very worthy to invest on the innovation as the

subsequent benefits to patients, healthcare professionals and the hospital are much

more significant

  31  

Evidence-Based Practice Guideline

According to the evidence derived form the reviewed studies in the previous

chapter, an evidence-based guideline of preoperative forced-air warming in reducing

inadvertent perioperative hypothermia for patients undergoing general anesthesia will

be developed. The recommendations will be graded according to the Scottish

Intercollegiate Guidelines Network (SIGN) grading system (SIGN, 2014). The full

guideline was attached in Appendix V.

                                                     

  32  

CHAPTER 4: IMPLEMENTATION PLAN

From the previous chapters, an evidence-based guideline was established for

the application of preoperative forced-air warming to IPH. In this chapter, the

implementation plan will be discussed including communication plan, pilot study

plan, evaluation plan, and the basis for the full implementation of the innovation.

Communication Plan

Before implementing the innovation, it is necessary to communicate with the

stakeholders who will be affected by the innovation or may affect the proposed

changes for the innovation. The communication process, the way to initiate, guide and

sustain the changes will be discussed followed.

Identifying the Stakeholders

The stakeholders of the innovation are the administrators, the committee

members leading the changes, the intended users of this evidence-based guideline,

other healthcare professionals and the patients undergoing GA being affected by the

guideline.

The administrators include the DOM and the Ward Managers (WM). Their

approval and support for the proposed guideline are very crucial as they provide

resources and allow manpower for the implementation of the innovation.

A committee team will be formed to initiate, guide and sustain the changes

brought form the guideline. One Advanced Practiced Nurse (APN) and three RNs will

be suggested to recruit for the committee team including myself. As the team takes

the leading role of the guideline, it is important that all the team members are very

  33  

clear about the guideline and have a consensus for the implementation of the

innovation.

The intended users of the guideline are the operating theatre nurses who carry

out the innovation for the patients. Their workflow will be changed and the workload

will be increased. Therefore their understanding of the implementation of the

innovation is very essential.

Other healthcare professionals including the anesthetists and the surgeons are

also the stakeholders. Although they are not directly related to the innovation, their

support and cooperation are also important for the smooth implementation of the

innovation. Besides, they may have to help provide information or examination in

some situations.

Patients undergoing GA who are included in the innovation will be directly

affected. Clear explanation has to be given to gain their understanding and

cooperation and to prevent any adverse situations such as thermal discomfort.

Communication Process

In order to have a success implementation of the guideline, effective

communication with the stakeholders are very important. They have to be convinced

in order and skillfully. Understanding their points of view, worries and tackle with the

obstacles are essential steps before the implementation.

Communication with administrators

In order to gain support form the administrators, the significance of the

problem, the affirming needs in the department, the gap between our current practice

and the evidence-based practice from the literature, and the benefit of the innovation

  34  

will be stressed on. Clear visions on the necessity to change and the aims and

objectives to be achieved will be stated. A feasible and well-organized proposal for

the implementation of the guideline will be submitted and presented to the

administrators during the departmental meeting. The budget plan, required resources

and the foreseeable barriers with tackling strategies will also be presented in the

meeting.

Communication with committee members

After the approval from the administrators, a committee team will be formed

to initiate, guide and sustain the change brought from the guideline. Certainly, the

team has to share the same vision and has a throughout understanding of the guideline

as we will act as the leaders, the facilitators and the resources people for the

implementation of the guideline. Application of the innovation will be standardized

within the team before we present to our colleagues. Workloads will be share among

the team members and timeframe for the process will be set. We will keep close

communication for the progress and discuss for any tackled difficulties in regular

meetings. We are also responsible for collecting feedback form the colleagues and

share among the team.

Communication with nursing staff

Communication with nursing staff will be started through promotion by

posters. Two identical briefing sessions will then be held during the in-house

mandatory training sessions, which are held on two Saturday morning so that all staff

will have the chance to attend the briefing sessions. As the nursing staff takes the key

role to implement the innovation and their workload are mostly affected by the

implementation of the guideline. They have to be convinced of the significance and

  35  

the needs of the innovation with evidence support. The benefits of the innovation to

the patients, the staff themselves and the healthcare system will be highlighted. The

clear and easily followed guideline will be introduced in detailed. The kept updated

guideline document will also be kept in the iPad in each floor of the operating theatre

for easy access. As the procedure of applying the innovation is easy, quick and

familiar to the nursing staff, it is believed that they have the confidence in applying

the innovation. Therefore the key point is to let them trust on the proposed guideline

and willing to implement.

Besides initiation and guidance, sustaining the change process is also

important. The nurses may be willing to implement the innovation but hindered by the

heavy workload or limited manpower. Therefore, regular collection of feedback on

any difficulties from the nursing staff is required. Both the outcome and process

evaluation have to be done regularly. The improvement in patient’s outcome can act

as a reward to the staff and encourage them to sustain the good practice. Besides,

nurses’ compliance will also be assessed monthly by auditing the nursing

documentation.

Communication with other healthcare professionals

As the implementation of the guideline requires earlier pre-medication and

sending the patient to the operation theatre, communication with the anaesthetists and

surgeons is important to facilitate the implementation. Besides, assessment on patients’

medical history and current medical problem is necessary to exclude those patients

who are not suitable for the innovation. The anaesthetists and surgeons may give help

in this part as well. When there are some adverse effects developed after

implementation of the innovation, we may also require their help for examination and

treatment. Therefore, their understanding and support act as the backup for our

  36  

practice. With the permission of the administrators, we will send email to the Chief of

Service of anesthesiology and department of surgery to introduce and explain the

implementation of the innovation.

Communication with the patients

As said above, the patient has to be sent to the operation theatre earlier for the

implementation of the innovation. That means they have to wait for a longer time in

the theatre before undergoing GA and the surgical procedure. This may increase their

anxiety level and nervousness if we don’t explain well to them. Thus we have to gain

their understanding and cooperation before applying the innovation. Assessments for

the present of any exclusion factors as well as regular temperature monitoring have to

be performed. Patient should be told to voice out any thermal discomfort or presence

of adverse effect as soon as they experience it. The nurse who admits the patient will

be responsible to explain verbally to the patient after admission and before carrying

out the innovation.

Pilot Study Plan

Before implementation the innovation, a pilot test will be conducted to

determine the feasibility of the proposed change and to identify any unexpected

difficulties so as to determine whether revisions of the guideline are required.

Timeframe

After providing the briefing sessions to the nursing staff, the pilot test will

then be launched. It will last for six weeks with four week testing the innovation and

the following two weeks for evaluation of the pilot test.

  37  

Implementation Plan

The pilot test will be launched in one of the floors of the Operating Theatre

(OT) department, which consists of two operation theatres. The guideline in the

previous chapter will be followed for the implementation of the innovation. Only

patients undergoing GA for elective surgery will be included for the innovation

(Andrzejowski et al., 2008; Erdling & Johansson, 2015; Fettes et al., 2013; Horn et

al., 2012; Kim et al., 2006; Shin et al., 2015). During the pilot test period, the

committee team members will screen the patients who are undergoing scheduled

operations the following day for the age, ASA status, the medical history and their

current medical problem. Eligible patients will be marked on the printed operation list

and the list will be hang over to the nurses who are working in the theatres the next

day. Patients aged over 18 with ASA < 3 will be recruited (Andrezejowski et al.,

2008; Erdling & Johansson, 2015; Fettes et al., 2013; Horn et al., 2012). Patients will

be excluded if they have fever, know infection, thyroid disease, peripheral vascular

disease and neurological disease (Erdling & Johansson, 2015; Fettes et al., 2013; Kim

et al., 2006; Shin et al., 2015). According to the usual scheduled operation list, it is

estimated to have 12 patients who are eligible for the implementation of the

innovation in a week. Thus in total there will be about 48 patients recruited for the

pilot test in a month. Committee members will be responsible to guide and monitor

the implementation.

All operation theatre nurses who have attended the briefing sessions can apply

the innovation. Assessment and patient’s core temperature should be taken before

providing the forced-air warming blanket. Continuous temperature monitoring should

be performed and documented on the nursing chart for temperature monitoring. The

committee members will audit the implementation of the innovation once a week and

  38  

collect feedback from the nursing staff in that floor. Any difficulties encountered will

be discussed in the committee team and the guideline will be revised accordingly if

required.

Evaluation Plan of Pilot Study

After the four weeks of pilot test, the feasibility for the implementation of the

innovation will be evaluated in the following two weeks. Nurses working on the floor,

which the pilot test carried out, will be invited to complete a questionnaire (Appendix

I) for evaluation. The questionnaire is composed of two parts. There are 8 questions in

Part A, which ask about the nurses’ satisfactory level for the new practice. It includes

the influence on their workload, the availability and sufficiency of the resource

manual and person and the overall satisfactory level to the new practice. Part B

consists of 6 questions asking about the nurses’ confidence level on carrying out the

innovation independently. Likert scale is used in the questionnaire for the nurses to

choose. There are also some open-ended questions for the nurses to express their

opinion. The committee team will then collect the completed questionnaire and revise

the guideline accordingly if required.

Evaluation Plan

In order to evaluate the effectiveness of the innovation, an evaluation plan will

be established as followed to identify outcomes to be achieved and to determine the

nature and number of clients to be involved. The method of data analysis will also be

specified.

  39  

Outcomes

Patient outcomes

The primary patient outcome of the innovation is to reduce the incidence rate

of IPH for patients undergoing GA. Therefore the number of patients who developed

hypothermia post induction will be measured (Andrzejowski et al., 2008; Fettes et al.,

2013; Hornet al., 2012; Shin et al., 2015). The circulating nurses will record the

baseline temperature, pre-induction temperature, and post-induction temperature at 20

min interval until the end of the surgery on the nursing chart for temperature

monitoring. The PACU nurses will continue the temperature monitoring when

patients arrive PACU. Temperature will be measures at arrival and at 20 min interval

until the patients were discharged to ward. The PACU nurse will record the number of

patients who develop IPH every day. A tympanic thermometer will be used for

temperature monitoring pre-, intra- and post-operatively so as to eliminate the

temperature difference due to the change in measuring tools.

Healthcare provider outcomes

Outcomes for healthcare provides are to increase their job satisfactory and

confidence level on applying the innovation. The questionnaire (Appendix VI) will be

used for evaluation. It will be distributed to all nurses after the implementation.

Besides, the compliance rate of the healthcare providers will also be evaluated by a

monthly audit done by the committee team.

Timeframe

Implementation of the full-scale innovation will start immediately after the

two weeks evaluation of the pilot test and will last for 24 months. The evaluation

  40  

process will go along with the implementation and a monthly evaluation report will be

generated. The improvement in patient outcomes may increase healthcare satisfaction

and their compliance rate. There will be a four-week evaluation period after the

implementation period for the overall evaluation and to determine whether the

innovation will be fully implemented. Details of the timeframe are shown in

Appendix VII.

Client

Eligibility criteria

Patients aged over 18 years old undergoing GA for elective surgery with ASA

< 3 will be recruited for the innovation. Patients with fever, known infection, thyroid

disease, peripheral vascular disease and neurological disease will be excluded for the

innovation.

Sample size

Sample size is calculated by using Piface statistical power analyzer. One

sample t-test is selected because the mean difference within the same group of clients

was compared. With reference to the study by Kim et al. (2006), by inputting the

mean difference of 0.5°˚C, change of standard deviation (SD) as 3 with 80% power,

the sample size was calculated to be 284. By considering 17% and 12% of dropout

rate in the studies done by Erdling and Johansson (2015) and Fettes et al. (2013)

respectively, the dropout rate of client in this innovation was estimated to be 20%. By

taking 20% of dropout rate, the sample size will be 355. Therefore 355 clients have to

be recruited.

  41  

Data Analysis

Data collection include patient demographics, number of patients developed

IPH, and the results from the evaluation questionnaire. Data will be analyzed by SPSS

19.0 (IBM Inc. Armonk, NY, USA). Patients’ demographic data will be compared

using chi-square or Fisher’s exact test as appropriate. A two-tail z-test will be used to

test the proportion of patients who developed IPH. For the results from the evaluation

questionnaire, nurses’ satisfactory and confidence level will be analyzed. The

percentage of nurses who choose either “agree” or “strongly agree” in the Likert scale

will be calculated.

Basis for Implementation

Results from Horn et al. (2012) showed 6-13% of patients develop IPH in the

prewarming group while Andrzejowski et al. (2008) showed 32 %. Thus the

innovation will be considered as effective if the percentage of patients developed IPH

is lower than 30%. Besides, the percentage of nurses’ job satisfactory and confidence

level will also determine the effectiveness of the guideline. If more than 80% of

nurses choosing “agree” or “strongly agree” in the questionnaire, the guideline will be

considered as effective. The innovation will be fully implemented if the above two

criteria were fulfilled.

   

  42  

Conclusion

Preventing perioperative hypothermia for patients undergoing general

anesthesia is very important to reduce the subsequent complications and improve

patients’ outcome. Evidences from the studies showed that preoperative forced-air

warming is an effective way to help reduce the incidence of perioperative

hypothermia by reducing the core and peripheral temperature gradient thus lower the

effect of core-to-peripheral heat redistribution after induction. With the evidence

extracted from the studies, an evidence-based guideline for providing preoperative

forced-air warming for patients undergoing general anesthesia is established. The

implementation potential is assessed. The subsequent implementation and evaluation

plans are also developed to help promote the successful implementation of the

innovation.

 

Wong Hoi Ching 2006171980

From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097

For  more  information,  visit  www.prisma-­‐statement.org.

43

Appendix I - PRISMA 2009 Flow Diagram

Records  identified  through  Pubmed,  Cochrane  Library  

(n  =  47)  

Screen

ing  

Includ

ed  

Eligibility  

Iden

tification  

Additional  records  identified  through  Google  Scholar  Engine    

(n  =  24)  

Records  after  duplicates  removed  (n  =  32)  

Records  screened  (n  =  9)  

Records  excluded  (n  =  23)  

Full-­‐text  articles  assessed  for  eligibility  

(n  =  6)  

Full-­‐text  articles  excluded,  with  reasons  

(n  =  3)  

Studies  included  in  qualitative  synthesis  

(n  =  6)  

Studies  included  in  quantitative  synthesis  

(meta-­‐analysis)  (n  =  0)  

Wong Hoi Ching

Appendix II - Table of Evidence 2006171980

44  

Citation/ Design (Level of Evidence)

Patient Characteristic

Intervention (Method/ Temperature/ Duration)

Comparison Outcome measures

Measuring Tools/Site/ Time Intervals (TI) for body temperature

Effect size/Results

Andrzejow-ski et al. (2008) /RCT (++)

1) Undergoing elective Spinal Surgery 2) Under GA1 3) ASA1 < 3

Prewarming with the Bair Paws® forced-air warming system at 38°C for 60 min (mean duration = 72 ± 26 min) (n=31)

Wearing a Bair Paws® gown without prewarming (n=37)

Primary: (1) Changes in mean core temperature (°C) at 20min intervals post induction Secondary: (2) Incidence of nausea, vomiting and shivering in PACU1 (Intervention: Control) (3) No. of Patient who were hypothermia throughout surgery (%)

Tools: Temporal artery scanner & esophageal temperature probe Site: Temporal artery & Esophagus TI1: Pre-intervention (Tpre), Pre- induction (T0), and at 20min intervals post-induction till 160min (T20-160)

Primary: (Effect size) (1) Tpre: 0, T0: -0.11, T20: 0.22, T40: 0.26, T60: 0.26, T80: 0.22, T100: 0.22, T120: 0.21, T140: 0.07, T160: 0 (p≤0.05 only at T40, T60, and T80) Secondary: (Results) (2) Nausea 3:2, Vomiting 3:1, and Shivering 2:3 (3) 25% in intervention group (p<0.05)

Erdling et al. (2015) /RCT (+)

1) Adults undergoing elective colorectal surgery 2) Under GA and EA2 > 210min 3) ASA < 3

Prewarming with a forced-air device set at 43°C after epidural catheter insertion and continue throughout surgery (mean duration = 42 ± 10min) (n=21)

Warming with a forced-air device after surgical preparation completed (n=22)

Primary: (1) Difference in esophageal temperature between groups (2) Difference in nasopharyngeal temperature between groups Secondary: (3) Relationship between esophageal temperature and age (4) Relationship between esophageal temperature and BMI2 at 210 min (BMI <25 and ≥25)

Tools: Esophageal and nasopharyngeal temperature probes Site: Lower esophagus and nasopharynx TI1: Pre-intervention, Pre-induction, before surgery start, and at 30min intervals during surgery till 210 min

Primary: (Effect size) (1) 0.46 (p=0.001) (2) 0.46 (p=0.002) Secondary: (Results) (3) A negative correlation between esophageal temperature and age (p<0.012) (4) Statistical differences between esophageal temperature and 2 BMI groups (BMI <25 and ≥25) at 35.81 ± 0.66 and 36.46 ± 0.59 (p<0.001)

1) GA = General Anesthesia; ASA = American Society of Anesthesiologists physical status classification system; PACU = Post-anesthesia Care Unit; TI = Time Intervals; T40, T60 and T80 = Core temperature at 40min, 60 min and 80min after induction 2) EA = Epidural analgesia; BMI = Body Mass Index (kg/m2

Wong Hoi Ching

Appendix II - Table of Evidence 2006171980

45  

Citation/ Design (Level of Evidence)

Patient Characteristic

Intervention (Method/ Temperature/ Duration)

Comparison Outcome measures

Measuring Tools/Site/ Time Intervals (TI) for body temperature

Effect size/Results

Fettes et al. (2013) /RCT (-)

1) Adults between 18 & 85 years old 2) Speak in English 3) ASA < 3 4) Body temperature between 36.5 and 37.5°C

Prewarming with forced-air warming blanket set at 37.8°C for about 60 min (n=54)

Covering with a warm cotton blanket and a forced-air warming blanket without turning on (n=74)

Primary: (1) Patient’s temperature on admission to PACU (°C) (2) Post-anesthesia care unit length of stay (min)

Tools: Temporal artery scanner Site: Temporal artery TI: Pre-induction and on admission to PACU

Primary: (Results) (1) 0.1°C in intervention group (p=0.314) (2) -2.6min in intervention group (p=0.526)

Horn et al. (2012) /RCT (++)

1) Healthy adults ≥18 years old 2) Scheduled for surgery with expected duration of 30-90 min 3) Under GA 4) ASA < 3

Active pre-operative forced-air warming at 44°C for 10, 20 or 30 min (n=52, 43 and 50 respectively)

Passive insulation (no active pre-operative warming) (n=55)

Primary: (1) No. of patient who were hypothermia at arrival of PACU (%) (2) No. of patients experienced shivering in PACU (%) Secondary: (3) No. of patient required active warming during surgery (%) (4) No. of patient required active warming in PACU (%)

Tools: Tympanic temperature sensor Site: Tympanic membrane TI: At 10min intervals after arrival pre-op care unit, 15min interval after arrival theatre and PACU

Primary: (Results) (1) -56%, -62% and -63% in 10, 20 and 30 min intervention group respectively (p<0.05) (2) -13%, -11% and -16% in 10, 20 and 30 min intervention group respectively (p<0.05) Secondary: (Results) (3) -36%, -65% and -61% in 10, 20 and 30 min intervention group respectively (p<0.05) (4) -52%, -63% and -57% in 10, 20 and 30 min intervention group respectively (p<0.05)

Wong Hoi Ching

Appendix II - Table of Evidence 2006171980

46  

Citation/ Design (Level of Evidence)

Patient Characteristic

Intervention (Method/ Temperature/ Duration)

Comparison Outcome measures

Measuring Tools/Site/ Time Intervals (TI) for body temperature

Effect size/Results

Kim et al. (2006) /RCT (++)

1) Undergoing OPCAB3

Warming with a Bair Hugger® forced-air heater set at 40°C before induction of anesthesia (mean duration = 49.7 ± 9.9 min) (n=20)

Covering with two cotton blankets (n=20)

Primary: (1) Changes in mean skin temperature (°C) at 30min intervals post induction (2) Changes in mean core temperature (°C) at 30min intervals post induction Secondary: (3) Hemodynamic changes include cardiac index, MAP3, CVP3, MPAP3, heart rate, and SVRI3

Tools: Skin temperature probe & Pulmonary artery catheter Site: Right index finger & Core temperature TI: Pre-induction (T0), and at 30min interval post-induction till 90min (T30-90)

Primary: (Effect size) (1) T0: 0.26, T30: 0.08, T60: 0.10, and T90: 0.03 (p<0.05) (2) T0: 0, T30: 0.31, T60: 0.28, and T90: 0.34 (p<0.05) Secondary: (Effect size) (3) No statistically significant differences in hemodynamic variables between two groups except MAP & CVP

Shin et al. (2015) /RCT (++)

1) Patients aged 20-80 years 2) Undergoing elective or emergency endovascular treatment of cerebral aneurysm 3) Under GA

Prewarming with a forced-air warming blanket set at 38°C for 30min with intraoperative warming (n=36)

Covering with two layers of cotton blanket without prewarming, with intraoperative warming (n=36)

Primary: (1) Changes in mean core temperature (°C) at 20min intervals post induction (2) No. of patient who were hypothermia at 20min intervals post induction (%) Secondary: (3) No. of patient developed procedure-related complication (%) (4) No. of patient experienced shivering in PACU (%)

Tools: Infrared tympanic thermometer and esophageal temperature probe Site: Tympanic membrane and esophagus TI: Pre-induction (Tpre), after intubation (T0), and at 20min intervals during surgery till 120min

Primary: (Results) (1) T0: 0.1°C, T20: 0.4°C, T40: 0.5°C, T60: 0.4°C, T80: 0.4°C, T100: 0.4°C, T120: 0.4°C in intervention group (p=0.007 at T20, p<0.001 at T 40-120) (2) T0: -8.3%, T20: -25%, T40: -50%, T60: -60%, T80: -52.6%, T100: -49.7%, T120: -23.8% in intervention group (p=0.002 at T20, p<0.001 at T 40-120) Secondary: (Results) (3) IAP4 1:1; Thromboembolic complication 1:2 (Intervention: control) (p=0.840) (4) -12% in intervention group (p=0.283)

3) OPCAB = Off-pump coronary artery bypass surgery; MAP = Mean arterial pressure; CVP = Central venous pressure; MPAP = Mean pulmonary arterial pressure; SVRI = Systemic vascular resistance index 4) IAP = Intraprocedural aneurysmal perforation

Wong Hoi Ching Appendix III – Summary of Appraisal Results 2006171980

  47  

In a well conducted RCT study… Does the study do it?

Andrzejowski  et  al.,  2008   Erdling  et  al.,  2015 Fettes  et  al.,  2013 Horn  et  al.,  2012   Kim  et  al.,  2006   Shin  et  al.,  2015

SECTION 1: INTERNAL VALIDITY

1.1 The study addresses an appropriate and clearly focused question. Yes Yes Yes Yes Yes Yes

1.2 The assignment of subjects to treatment groups is randomized. Yes Yes Yes Yes Yes Yes

1.3 An adequate concealment method is used. Yes Can’t say Can’t say Yes Yes Yes

1.4 The design keeps subjects and investigators “blind” about treatment allocation.

Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable

1.5 The treatment and control groups are similar at the start of the trial. Yes Yes Yes Yes Yes Yes

1.6 The only difference between groups is the treatment under investigation. Yes Yes Yes No Yes Yes

1.7 All relevant outcomes are measured in a standard, valid and reliable way.

Yes Yes Yes Yes Yes Yes

1.8

What percentage of the individuals or clusters recruited into each treatment arm of the study dropped out before the study was completed?

0% 17% 12% 0% 0% 0%

1.9

All the subjects are analysed in the groups to which they were randomly allocated (often referred to as intention to treat analysis).

Yes No No Yes Yes Yes

1.10 Where the study is carried out at more than one site, results are comparable for all sites.

Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable

Wong Hoi Ching Appendix III – Summary of Appraisal Results 2006171980

  48  

In a well conducted RCT study… Does the study do it?

Andrzejowski  et  al.,  2008 Erdling  et  al.,  2015 Fettes  et  al.,  2013 Horn  et  al.,  2012 Kim  et  al.,  2006 Shin  et  al.,  2015

SECTION 2: OVERALL ASSESSMENT OF THE STUDY

2.1

How well was the study done to minimize bias? (High quality: ++, Acceptable: +, Low quality: -, Unacceptable – reject: 0)

++ + - ++ ++ +

2.2

Taking into account clinical considerations, your evaluation of the methodology used, and the statistical power of the study, are you certain that the overall effect is due to the study intervention?

Yes Yes Can’t say Yes Yes Yes

2.3 Are the results of this study directly applicable to the patient group targeted by this guideline?

Yes Yes Yes Yes Yes Yes

2.4

Notes. Summarise the authors’ conclusions. Add any comments on your own assessment of the study, and the extent to which it answers your question and mention any areas of uncertainty raised above.

- It is concluded that 60 min of prewarming is effective to attenuate the redistribution hypothermia after anesthesia and decrease the incidence of IPH - The conclusion is supported by the study results

- It is concluded that prewarming has a positive effect on core temperature of patients under GA - The conclusion is supported by the study results

- It is concluded that prewarming does not significantly affect patient’s postoperative temperature. - The differences in group sample size may affect the statistical outcomes

- It is concluded that prewarming of 10, 20 or 30 min reduced the risk of perioperative hypothermia - There is no significant differences between 10, 20 or 30 min of prewarming groups - The conclusions are supported by the study results

- It is concluded that prewarming reduced the incidence and degree of redistribution hypothermia in patients undergoing OPCAB1 - The conclusion is supported by the study results

- It is concluded that 30 min of prewarming at 38°C was not enough to prevent the decrease in core temperature but reduce the incidence of hypothermia - The conclusion is supported by the study results

1) OPCAB = Off-pump coronary artery bypass surgery

Wong Hoi Ching 2006171980

  49  

Appendix IV – Summary of Costs of the Implementation of the Innovation Material Cost: Set-up cost Category Calculation Sub-total

Forced-air warming device $14,800 x 10 $148,000

Full-body forced-air blanket $75 x 60 $4,500

Photocopying of guidelines (10 pages/set)

$0.3 x 10 x 6 $18

Total $152,518

Running cost per year Category Calculation Sub-total

Full-body forced-air blanket $75 x 60 x 12 $54,000

Photocopying of assessment & evaluation form (1 pages/set)

$0.3 x 3600 $1,080

Total $55,080

Training cost Average 30 min salary of RN $90 X Number of RN in operation theatre 120 Total nonmaterial cost for the briefing sessions $10,800

Wong Hoi Ching 2006171980

  50  

Appendix V - Evidence-Based Practice Guideline

Introduction

As inadvertent perioperative hypothermia is very common in patients

undergoing general anesthesia, the implementation of preoperative forced-air

warming is recommended with evidence support. An evidence-based guideline is

developed to provide instruction for nurses in the operation theatres on the provision

of preoperative forced-air warming for patients undergoing general anesthesia.

Title

An evidence-based guideline on providing preoperative forced-air warming

for patients undergoing general anesthesia

Aim

To reduce the incidence of perioperative hypothermia

Objectives

1) To provide an evidence-based guideline for nurses on providing preoperative

forced-air warming for patients undergoing general anesthesia

2) To standardize the nursing care related to the provision of preoperative forced-

air warming for patients undergoing general anesthesia

Intended Users

Nurses working in the operation theatres in the public hospital in HKWC

Wong Hoi Ching 2006171980

  51  

Target Population

Patients aged over 18 year old with American Society of Anesthesiologists

physical status classification system (ASA) < 3 undergoing general anesthesia for

elective surgery are the target population. Patients with fever, known infection,

thyroid disease, peripheral vascular disease and neurological disease are excluded.

Recommendations

The following recommendations are concluded with evidenced support from

the reviewed studies. The Scottish Intercollegiate Guidelines Network (SIGN)

grading system (SIGN, 2014) was used to grade the recommendations and the levels

of evidence (Appendix VI).

Recommendation 1

The eligible population should include adult patient aged > 18 year old with

ASA < 3 undergoing general anesthesia for elective surgery

(Grade of recommendation – A)

Evidence:

All studies include adult patients undergoing GA (Andrzejowski et al., 2008

(1++); Erdling & Johansson, 2015 (1+); Fettes et al., 2013 (1-); Horn et al., 2012

(1++); Kim et al., 2006 (1++); Shin et al., 2015 (1++)). Four studies mentioned about

the ASA status to be < 3 (Andrezejowski et al., 2008 (1++); Erdling & Johansson,

2015 (1+); Fettes et al., 2013 (1-); Horn et al., 2012(1+)).

Recommendation 2

Wong Hoi Ching 2006171980

  52  

Patients with fever, known infection, thyroid disease, peripheral vascular disease

and neurological disease should be excluded for the preoperative forced-air

warming

(Grade of recommendation – A)

Evidence:

Four studies excluded patients with fever, thyroid disease and peripheral

vascular disease (Erdling & Johansson, 2015(1+); Fettes et al., 2013(1-); Kim et al.,

2006(1++); Shin et al., 2015(1++)). Three studies excluded patients with known

infection and neurological disease (Fettes et al., 2013(1-); Kim et al., 2006(1++); Shin

et al., 2015(1++)).

Recommendation 3

A full-body forced-air warming blanket should be used for the preoperative

warming

(Grade of recommendation – A)

Evidence:

All studies used forced-air warming blanket for preoperative warming

(Andrzejowski et al., 2008 (1++); Erdling & Johansson, 2015 (1+); Fettes et al., 2013

(1-); Horn et al., 2012 (1++); Kim et al., 2006 (1++); Shin et al., 2015 (1++)). Four

studies mentioned about using full-body blanket (Andrzejowski et al., 2008 (1++);

Horn et al., 2012 (1++); Kim et al., 2006 (1++); Shin et al., 2015 (1++)).

Recommendation 4

The temperature of the forced-air warming device should be set between 40-

44°C

Wong Hoi Ching 2006171980

  53  

(Grade of recommendation – A)

Evidence:

Three studies set the temperature of the forced-air warming device between

40-44°C and got significant results (Erdling & Johansson, 2015 (1+); Horn et al.,

2012 (1++); Kim et al., 2006 (1++)).

Recommendation 5

The duration of the preoperative forced-air warming should be ≥ 30 min

(Grade of recommendation – A)

Evidence:

Majority of the studies prewarmed the patients ≥ 30 min ranging from 30 to 72

min ((Andrzejowski et al., 2008 (1++); Erdling & Johansson, 2015 (1+); Fettes et al.,

2013 (1-); Kim et al., 2006 (1++); Shin et al., 2015 (1++)).

Recommendation 6

Patients’ baseline body temperature should be measured before providing the

preoperative forced-air warming

(Grade of recommendation – A)

Evidence:

There studies mentioned about the significance of taking the baseline body

temperature before applying the preoperative warming (Andrzejowski et al., 2008

(1++); Horn et al., 2012 (1++); Kim et al., 2006 (1++))

Recommendation 7

Wong Hoi Ching 2006171980

  54  

Patients’ preoperative, intraoperative and postoperative body temperature

should be monitored at 20 min interval

(Grade of recommendation – A)

Evidence:

In majority of the studies, the preoperative, intraoperative and postoperative

temperature are monitored at a interval ranging from 10 – 30 min (Andrzejowski et

al., 2008 (1++); Erdling & Johansson, 2015 (1+); Horn et al., 2012 (1++); Kim et al.,

2006 (1++); Shin et al., 2015 (1++)).

Recommendation 8

During the preoperative warming period, patient’s thermal comfort should be

asked every 5 min. Lower the temperature of the warming device or terminate

the warming if patient complain of thermal discomfort or develop any adverse

reactions.

(Grade of recommendation – A)

Evidence:

Horn et al. (2012) (1++) stated the significance of monitoring for any thermal

discomfort by asking patients every 5 min. The warmer was lowered if they patients

felt overheated.

  55  

Appendix VI

Key to Evidence Statements and Grades of Recommendations (SIGN, 2011)

Wong Hoi Ching 2006171980

 

  56  

Appendix VII Questionnaire on Preoperative Forced-air Warming Application for Nurses Dear colleagues, Thank you for taking part in the application of preoperative forced-air warming for patients undergoing general anaesthesia in elective surgery. To evaluate the effectiveness of the new guideline, please spare 5 minutes time help us complete the following questionnaire. Your kindly help is much appreciated. Thank you. Part A – Satisfaction on preoperative forced-air warming application （Please tick the answer that most represent your feeling about the statement)

Strongly Disagree Disagree Neutral Agree Strongly

Agree

1. The application is easy to be carried out.

2. The application does not increase my workload.

3. The guideline manual is easy to locate.

4. The guideline is easy to follow.

5. The guideline provides enough information.

6. The resource person is easy to reach.

7. The resource person provides enough information.

8. Overall, I am satisfied with the new practice.

Do you have any suggestion about the preoperative forced-air warming application?

Wong Hoi Ching 2006171980

 

  57  

Part B - Confidence on preoperative forced-air warming application （Please tick the answer that most represent your feeling about the statement)

Strongly Disagree Disagree Neutral Agree Strongly

Agree

1. I am confident on patient assessment to recruit eligible patients.

2. I am confident on applying the new practice.

3. I am confident to explain the application to patients.

4. I am confident to manage the workflow of the new practice.

5. I am confidence on patient temperature monitoring.

6. Overall, I am confident of the new practice.

Do you have any suggestions to increase your confidence on preoperative forced-air warming application?  

Wong Hoi Ching 2006171980

  58  

Appendix VIII

Timeframe of the Implementation and Evaluation of the Innovation

Week  Schedule   2   4   6   8   10   12   14   16   18   20   22   24   26   28   30   32   34   36   38   40   42   44  

Preparation                                              

Staff  briefing                                              

Pilot  test  with  evaluation  

                                           

Implementation                                              

Evaluation                                              

 

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