C2005 Evidence Evaluation Template - Nov.11 2003circ.ahajournals.org/.../W52_Falcucci_Cain.doc · Web viewWORKSHEET for PROPOSED Evidence-Based ... Taskforce.Topic.Author.Date.Doc

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WORKSHEET for PROPOSED Evidence-Based GUIDELINE RECOMMENDATIONSNOTE: Save worksheet using the following filename format: Taskforce.Topic.Author.Date.Doc where Taskforce is a=ACLS, b=BLS, p=Pediatric, n=neonatal and i=Interdisciplinary. Use 2 or 3 letter abbreviation for author’s name and 30Jul03 as sample date format.Worksheet Author: Rebecca L. Cain, MD and Octavio Falcucci, MD

Taskforce/Subcommittee: __BLS _x_ACLS __PEDS __ID __PROAD__Other:

Author’s Home Resuscitation Council: _x_AHA __ANZCOR __CLAR __ERC __HSFC__HSFC __RCSA ___IAHF ___Other:

Date Submitted to Subcommittee: September 1, 2004; Revised 16 Dec 2004

STEP 1: STATE THE PROPOSAL. State if this is a proposed new guideline; revision to current guideline; or deletion of current guideline.Existing guideline, practice or training activity, or new guideline: New GuidelineWhen should we commence ventilation during cardiac arrest? Current AHA guidelines for adult CPR recommend a chest compression rate of 100 per minute and a respiratory rate of approximately 12 breaths per minute, with compression/ventilation ratios of 15:2 with one or two rescuers until the airway is secured.Step 1A: Refine the question; state the question as a positive (or negative) hypothesis. State proposed guideline recommendation as a specific, positive hypothesis. Use single sentence if possible. Include type of patients; setting (in- /out-of-hospital); specific interventions (dose, route); specific outcomes (ROSC vs. hospital discharge).Question: When should we commence ventilation during cardiac arrest?Hypothesis: Single-rescuer bystander should not commence ventilation in out-of-hospital witnessed cardiac arrest.Step 1B: Gather the Evidence; define your search strategy. Describe search results; describe best sources for evidence.Text words: Cardiac arrest AND ventilation AND start *NOT pediatric. 31 articles found (search up to August of 2004. The best source for evidences is the reference list of the selected articles)

List electronic databases searched (at least AHA EndNote 7 Master library [http://ecc.heart.org/], Cochrane database for systematic reviews and Central Register of Controlled Trials [http://www.cochrane.org/], MEDLINE [http://www.ncbi.nlm.nih.gov/PubMed/ ], and Embase), and hand searches of journals, review articles, and books.AHA EndNote 7, Cochrane, MEDLINE and Embase• State major criteria you used to limit your search; state inclusion or exclusion criteria (e.g., only human studies with control group? no animal studies? N subjects

> minimal number? type of methodology? peer-reviewed manuscripts only? no abstract-only studies?)Peer-reviewed articles only.• Number of articles/sources meeting criteria for further review: Create a citation marker for each study (use the author initials and date or Arabic numeral, e.g., “Cummins-1”). . If possible, please supply file of best references; EndNote 6+ required as reference manager using the ECC reference library.15 articles relevant to the topic were reviewed in detail 7 articles (LOE 2 to 6) inserted into grid. 8 LOE 7 articles not included.

STEP 2: ASSESS THE QUALITY OF EACH STUDYStep 2A: Determine the Level of Evidence. For each article/source from step 1, assign a level of evidence—based on study design and methodology.

Level of Evidence

Definitions(See manuscript for full details)

Level 1 Randomized clinical trials or meta-analyses of multiple clinical trials with substantial treatment effectsLevel 2 Randomized clinical trials with smaller or less significant treatment effectsLevel 3 Prospective, controlled, non-randomized, cohort studiesLevel 4 Historic, non-randomized, cohort or case-control studiesLevel 5 Case series: patients compiled in serial fashion, lacking a control groupLevel 6 Animal studies or mechanical model studiesLevel 7 Extrapolations from existing data collected for other purposes, theoretical analysesLevel 8 Rational conjecture (common sense); common practices accepted before evidence-based guidelines



Step 2B: Critically assess each article/source in terms of research design and methods. Was the study well executed? Suggested criteria appear in the table below. Assess design and methods and provide an overall rating. Ratings apply within each Level; a Level 1 study can be excellent or poor as a clinical trial, just as a Level 6 study could be excellent or poor as an animal study. Where applicable, please use a superscripted code (shown below) to categorize the primary endpoint of each study. For more detailed explanations please see attached assessment form.

Component of Study and Rating Excellent Good Fair Poor UnsatisfactoryDesign &

Methods

Highly appropriate sample or model, randomized, proper controls ANDOutstanding accuracy, precision, and data collection in its class

Highly appropriate sample or model, randomized, proper controlsOROutstanding accuracy, precision, and data collection in its class

Adequate, design, but possibly biased

ORAdequate under the circumstances

Small or clearly biased population or model

ORWeakly defensible in its class, limited data or measures

Anecdotal, no controls, off target end-points

ORNot defensible in its class, insufficient data or measures

A = Return of spontaneous circulation C = Survival to hospital discharge E = Other endpointB = Survival of event D = Intact neurological survival

Step 2C: Determine the direction of the results and the statistics: supportive? neutral? opposed?

DIRECTION of study by results & statistics: SUPPORT the proposal NEUTRAL OPPOSE the proposal

ResultsOutcome of proposed guideline superior, to a clinically important degree, to current approaches

Outcome of proposed guideline no different from current approach

Outcome of proposed guideline inferior to current approach

Step 2D: Cross-tabulate assessed studies by a) level, b) quality and c) direction (ie, supporting or neutral/ opposing); combine and summarize. Exclude the Poor and Unsatisfactory studies. Sort the Excellent, Good, and Fair quality studies by both Level and Quality of evidence, and Direction of support in the summary grids below. Use citation marker (e.g. author/ date/source). In the Neutral or Opposing grid use bold font for Opposing studies to distinguish them from merely neutral studies. Where applicable, please use a superscripted code (shown below) to categorize the primary endpoint of each study.

Supporting EvidenceSingle-rescuer bystander should not commence ventilation in out-of-hospital cardiac arrest

Qua

lity

of E

vide

nce

Excellent

GoodHALLSTROM, 2000 *(C) BERG,1993 (BD)

BERG, 1997 (ABD)

Fair



1 2 3 4 5 6 7 8Level of Evidence

A = Return of spontaneous circulation C = Survival to hospital discharge E = Other endpointB = Survival of event D = Intact neurological survival * = Dispatch assisted CPR

Neutral or Opposing EvidenceSingle-rescuer bystander should not commence ventilation in out-of-hospital cardiac arrest

Qua

lity

of E

vide

nce

Excellent

Good DORPH, 2004 (A)

Fair BRENNER, 1996 (B) NOC, 1994 (E)JAWAN, 2000 (E)

1 2 3 4 5 6 7 8Level of Evidence

A = Return of spontaneous circulation C = Survival to hospital discharge E = Other endpointB = Survival of event D = Intact neurological survival

STEP 3. DETERMINE THE CLASS OF RECOMMENDATION. Select from these summary definitions.CLASS CLINICAL DEFINITION REQUIRED LEVEL OF EVIDENCE

Class IDefinitely recommended. Definitive, excellent evidence provides support.

• Always acceptable, safe• Definitely useful • Proven in both efficacy & effectiveness• Must be used in the intended manner for proper clinical indications.

• One or more Level 1 studies are present (with rare exceptions) • Study results consistently positive and compelling

Class II:Acceptable and useful

• Safe, acceptable• Clinically useful• Not yet confirmed definitively

• Most evidence is positive• Level 1 studies are absent, or inconsistent, or lack power • No evidence of harm

• Class IIa: Acceptable and usefulGood evidence provides support

• Safe, acceptable• Clinically useful • Considered treatments of choice

• Generally higher levels of evidence• Results are consistently positive

• Class IIb: Acceptable and usefulFair evidence provides support

• Safe, acceptable • Clinically useful• Considered optional or alternative treatments

• Generally lower or intermediate levels of evidence• Generally, but not consistently, positive results

Class III: Not acceptable, not useful, may be harmful

• Unacceptable• Not useful clinically• May be harmful.

• No positive high level data• Some studies suggest or confirm harm.

Indeterminate• Research just getting started.• Continuing area of research• No recommendations until further research

• Minimal evidence is available• Higher studies in progress • Results inconsistent, contradictory• Results not compelling

STEP 3: DETERMINE THE CLASS OF RECOMMENDATION. State a Class of Recommendation for the Guideline Proposal. State either a) the intervention, and then the conditions under which the intervention is either Class I, Class IIA, IIB, etc.; or b) the condition, and then whether the intervention is Class I, Class IIA, IIB, etc.



Indicate if this is a __Condition or _x_InterventionSingle-rescuer bystander should not commence ventilation in out-of-hospital cardiac arrestFinal Class of recommendation: __Class I-Definitely Recommended __Class IIa-Acceptable & Useful; good evidence _x_Class IIb-Acceptable & Useful; fair evidence __Class III – Not Useful; may be harmful __Indeterminate-minimal evidence or inconsistent

REVIEWER’S PERSPECTIVE AND POTENTIAL CONFLICTS OF INTEREST: Briefly summarize your professional background, clinical specialty, research training, AHA experience, or other relevant personal background that define your perspective on the guideline proposal. List any potential conflicts of interest involving consulting, compensation, or equity positions related to drugs, devices, or entities impacted by the guideline proposal. Disclose any research funding from involved companies or interest groups. State any relevant philosophical, religious, or cultural beliefs or longstanding disagreements with an individual.

Rebecca L. Cain, MD - Cardiac Anesthesia Fellow, ACLS Instructor, Research activities in the areas of thoracic electrical bioimpedance, blood conservation and alternative anti-coagulants. No conflicts of interest except academic publication and presentationOctavio Falcucci, MD - Cardiac Anesthesiologist – Critical Care Intensivist. Research in cardiopulmonary function. No conflicts of interest except academic publication and presentation

REVIEWER’S FINAL COMMENTS AND ASSESSMENT OF BENEFIT / RISK: Summarize your final evidence integration and the rationale for the class of recommendation. Describe any mismatches between the evidence and your final Class of Recommendation. “Mismatches” refer to selection of a class of recommendation that is heavily influenced by other factors than just the evidence. For example, the evidence is strong, but implementation is difficult or expensive; evidence weak, but future definitive evidence is unlikely to be obtained. Comment on contribution of animal or mechanical model studies to your final recommendation. Are results within animal studies homogeneous? Are animal results consistent with results from human studies? What is the frequency of adverse events? What is the possibility of harm? Describe any value or utility judgments you may have made, separate from the evidence. For example, you believe evidence-supported interventions should be limited to in-hospital use because you think proper use is too difficult for pre-hospital providers. Please include relevant key figures or tables to support your assessment.Literature search identified one LOE 2 study, one LOE 5 study, four LOE 6 studies and eight LOE 7 studies (see citation list).Many of the relevant clinical and animal studies, as well as reviews of past studies, show that survival rates associated with chest compression alone are similar to those with chest compression plus mouth-to-mouth ventilation. Other studies or experimental data have also shown:1. Within the first 10 minutes of cardiac arrest adequate oxygen exists within the blood (Kern 2000 LOE 7).2. There is not a survival disadvantage if adequate circulation is provided with chest compression alone vs chest compression with

ventilation (Hallstrom 2000 LOE 2; Kern 2000 LOE 7). 3. Both chest compressions and spontaneous gasping provide pulmonary ventilation and gas exchange (Noc 1994 LOE 6; Weil

1997 LOE 7; Berg 1997 LOE 6, Idris 1996 LOE 7).4. During the first few minutes of CPR chest compressions alone are as effective as chest compressions with mouth-to-mouth

ventilation (Berg 1993 LOE 6; Berg 1997 LOE 6; Hallstrom 2000 LOE 2).Chest compressions alone is easier to teach and is better remembered and performed by single-rescuer bystander (Berg 1993 LOE 6; Berg 1997 LOE 6; Kern 2000 LOE 7).

Preliminary draft/outline/bullet points of Guidelines revision: Include points you think are important for inclusion by the person assigned to write this section. Use extra pages if necessary.

Publication: Chapter: Pages:

Topic and subheading: Evidence from one prospective, randomized trial in dispatch assisted CPR in adults, and numerous additional studies (Level of Evidence 6 and 7) document that outcome after CPR with Chest Compressions alone is similar to that of traditional CPR with mouth-to-mouth ventilation during pre-hospital witnessed cardiac arrest. Therefore, chest compression only CPR should be considered in the treatment of witnessed cardiac arrest in a pre-hospital setting in the instance of a single-rescuer bystander as a Class IIb recommendation.



Attachments: Bibliography in electronic form using the Endnote Master Library. It is recommended that the bibliography be provided in annotated

format. This will include the article abstract (if available) and any notes you would like to make providing specific comments on the quality, methodology and/or conclusions of the study.



Citation List

Citation Marker Full Citation*Berg (1993) Berg, R. A., K. B. Kern, et al. (1993). "Bystander cardiopulmonary

resuscitation. Is ventilation necessary?" Circulation 88(4 Pt 1): 1907-15.

BACKGROUND. Prompt initiation of bystander cardiopulmonary resuscitation (CPR) improves survival. Basic life support with mouth-to-mouth ventilation and chest compressions is intimidating, difficult to remember, and difficult to perform. Chest compressions alone can be easily taught, easily remembered, easily performed, adequately taught by dispatcher-delivered telephone instruction, and more readily accepted by the public. The principal objective of this study was to evaluate the need for ventilation during CPR in a clinically relevant swine model of prehospital witnessed cardiac arrest. METHODS AND RESULTS. Thirty seconds after ventricular fibrillation, swine were randomly assigned to 12 minutes of chest compressions plus mechanical ventilation (group A), chest compressions only (group B), or no CPR (group C). Standard advanced cardiac life support was then provided. Animals successfully resuscitated were supported for 2 hours in an intensive care setting, and then observed for 24 hours. All 16 swine in groups A and B were successfully resuscitated and neurologically normal at 24 hours, whereas only 2 of 8 group C animals survived for 24 hours (P < .001, Fisher's exact test). One of the 2 group C survivors was comatose and unresponsive. CONCLUSIONS. In this swine model of witnessed prehospital cardiac arrest, the survival and neurological outcome data establish that prompt initiation of chest compressions alone appears to be as effective as chest compressions plus ventilation and that both techniques of bystander CPR markedly improve outcome compared with no bystander CPR.Comments: Level 6, Good, Supportive. Anesthetised, intubated swine model of VF (simulating bystander CPR) in which CPR (standard CPR with mechanical ventilation or Chest Compressions only) was instituted after 30 sec of VF and continued for 12 min until ACLS. Both survival at 24 hrs and neurological status (cerebral performance category 1) were identical (100%) in both experimental groups.

Berg (1997) Berg, R. A., K. B. Kern, et al. (1997). "Assisted ventilation does not improve outcome in a porcine model of single-rescuer bystander cardiopulmonary resuscitation." Circulation 95(6): 1635-41.

BACKGROUND: Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for assisted ventilation during simulated single-rescuer bystander CPR in a



swine model of prehospital cardiac arrest. METHODS AND RESULTS: Five minutes after ventricular fibrillation, swine were randomly assigned to 8 minutes of hand-bag-valve ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC + V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. All 10 CC animals, 9 of the 10 CC + V animals, and 4 of the 6 control animals attained return of spontaneous circulation. Five of the 10 CC animals, 6 of the 10 CC + V animals, and none of the 6 control animals survived for 24 hours (CC versus controls, P = .058; CC + V versus controls, P < .03). All 24-hour survivors were normal or nearly normal neurologically. CONCLUSIONS: In this model of prehospital single-rescuer bystander CPR, successful initial resuscitation, 24-hour survival, and neurological outcome were similar after chest compressions only or chest compressions plus assisted ventilation. Both techniques tended to improve outcome compared with no bystander CPR.Comments: Level 6, Good, Supportive. Anesthetised, intubated swine model of VF (simulating single-rescuer bystander CPR) in which CPR (standard CPR with assisted ventilation or Chest Compressions only) was instituted after 5 min of VF and continued for 8 min until ACLS. Both survival at 24 hrs and neurological status (cerebral performance category 1) were almost identical in both experimental groups.

Brenner (1996) Brenner, B. E. and J. Kauffmann (1996). "Response to cardiac arrests in a hospital setting: delays in ventilation." Resuscitation 31(1): 17-23.

The outcome following a cardiac arrest is affected by the length of time that elapses before cardiopulmonary resuscitation is initiated. Only 10-15% of patients experiencing cardiac arrest in hospital settings survive to discharge. Therefore, the time between cardiac arrest and administration of cardiopulmonary resuscitation in a metropolitan hospital was examined. All cardiac and respiratory arrests that occurred in the adult non-intensive care areas of a medical center over a period of 16 months were evaluated within 12 h to determine how much time had elapsed before resuscitation was initiated, the devices utilized for initial airway management, and the outcome. To initiate ventilation, bag-valve-masks (BVMs) were used in the majority (76%) of the efforts to resuscitate while mouth-to-mask resuscitation was performed in another 18%; however, in only 37% of the codes was ventilation initiated within 1 min and in 18% ventilation was started after 3 min. Mouth-to-mask resuscitation resulted in more rapid time to onset of ventilation than BVM. In only 18% of the arrests studied was a 'lay-on' mask available in the room and utilized. In 11%, a bag-valve-mask was at the patient's bedside,



and in 53% a BVM was taken from the crash cart outside the room. In 63% of the cases where using a lay-on mask was appropriate, it was either not looked for or not present in the patient's room. Also in 37% of the cases where a BVM was needed, one was not readily present because of difficulty in locating the crash cart immediately. Although initiation of cardiopulmonary resuscitation within a minute of a cardiac or respiratory arrest is the standard of care, in the non-intensive care in-patient cases surveyed, typically more than a minute elapsed, and frequently 3 or more minutes, before resuscitation was started. If the time elapsing before an arresting in-patient is ventilated can be shortened, which is easily and effectively achieved by mouth-to-mouth or mouth-to-mask resuscitation, an increase in both the survival rate and the number of good neurological outcomes should be expected.Comments: Level 5, Fair, Non-supportive. Retrospective time-recall study of 38 adult cardiac or respiratory arrests (codes) in the adult non-intensive care areas of the hospital. Cases were evaluated within 12 hrs. 100% mortality in those patients in whom chest compressions were initiated before ventilation.

Dorph (2004) Dorph, E., L. Wik, et al. (2004). "Oxygen delivery and return of spontaneous circulation with ventilation:compression ratio 2:30 versus chest compressions only CPR in pigs." Resuscitation 60(3): 309-18.

The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5-2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation



improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended.Comments: Level 6, Good, Neutral. Anesthetised, trached swine model of VF (simulating mouth-to-mouth ventilation during BLS with an obstructed airway) in which BLS (Chest Compressions only or Ventilation-Chest Compression ratio of 2:30) was instituted after 3 min of VF and continued for 10 min until ALS. ROSC shorter and better cerebral oxygen delivery in those swine receiving chest compressions with mechanical ventilation.

Gueugniaud (2002) Gueugniaud, P. Y., J. S. David, et al. (2002). "[New aspects and perspectives on cardiac arrest]." Ann Fr Anesth Reanim 21(7): 564-80.

OBJECTIVES: To analyse the current knowledge based on the experimental and the clinical research studies focused on the main fields of cardiopulmonary resuscitation. DATA SOURCES: International guidelines and recent review articles. Data collected from the Medline database with the key word: cardiac arrest. STUDY SELECTION: Research studies published during the last ten years were reviewed. Relevant clinical information was extracted and discussed when it induced changes in guidelines. DATA SYNTHESIS: Promising improvements on basic and advanced life supports are proposed. Chest compressions prevail over ventilation. Alternatives to classical chest compressions are tested. Ventilatory volume must be reduced from 1000 to approximatively 500 mL for each breath with oxygen. Biphasic waveform defibrillators and automated external defibrillators will be considered as the best devices in the near future. Some non-catecholaminergic vasopressors could reduce the use of epinephrine for advanced cardiac life support. Lidocaine could be replaced by amiodarone as anti-arrhythmic drug of choice. New post-resuscitation therapeutic strategies are evaluated, especially coronary reperfusion when the cause of cardiac arrest is cardiac. CONCLUSION: Many fields of cardiopulmonary resuscitation are investigated. Some relevant informations are included in the last international guidelines published in 2000, but most of them need complementary studies before other changes could be recommended for routine practice.Not included in table.Comments: Level 7, Review of Literature, Supportive. International guidelines and recent review articles during past 10 yrs. Many aspects of CPR investigated with one conclusion being chest compressions prevail over ventilation.

Hallstrom (2000) Hallstrom, A., L. Cobb, et al. (2000). "Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation." N Engl J Med 342(21): 1546-53.

BACKGROUND: Despite extensive training of citizens of Seattle in cardiopulmonary resuscitation (CPR), bystanders do not



perform CPR in almost half of witnessed cardiac arrests. Instructions in chest compression plus mouth-to-mouth ventilation given by dispatchers over the telephone can require 2.4 minutes. In experimental studies, chest compression alone is associated with survival rates similar to those with chest compression plus mouth-to-mouth ventilation. We conducted a randomized study to compare CPR by chest compression alone with CPR by chest compression plus mouth-to-mouth ventilation. METHODS: The setting of the trial was an urban, fire-department-based, emergency-medical-care system with central dispatching. In a randomized manner, telephone dispatchers gave bystanders at the scene of apparent cardiac arrest instructions in either chest compression alone or chest compression plus mouth-to-mouth ventilation. The primary end point was survival to hospital discharge. RESULTS: Data were analyzed for 241 patients randomly assigned to receive chest compression alone and 279 assigned to chest compression plus mouth-to-mouth ventilation. Complete instructions were delivered in 62 percent of episodes for the group receiving chest compression plus mouth-to-mouth ventilation and 81 percent of episodes for the group receiving chest compression alone (P=0.005). Instructions for compression required 1.4 minutes less to complete than instructions for compression plus mouth-to-mouth ventilation. Survival to hospital discharge was better among patients assigned to chest compression alone than among those assigned to chest compression plus mouth-to-mouth ventilation (14.6 percent vs. 10.4 percent), but the difference was not statistically significant (P=0.18). CONCLUSIONS: The outcome after CPR with chest compression alone is similar to that after chest compression with mouth-to-mouth ventilation, and chest compression alone may be the preferred approach for bystanders inexperienced in CPR.Comments: Level 2, Good, Supportive. Randomized study in which CPR with chest compressions plus mouth-to-mouth ventilation was compared to CPR with only chest compressions in an urban, fire-department based, emergency-medical-care system with central dispatching. Even though survival to hospital discharge was better in the chest compression only group, it was not statistically significant.

Idris (1996) Idris, A. H. (1996). "Reassessing the need for ventilation during CPR." Ann Emerg Med 27(5): 569-75.

In the United States debate continues about the necessity of ventilation during CPR because of fear of contracting infectious diseases. Three questions will be considered in this article. First, is ventilation necessary for the treatment of cardiac arrest? Second, is mouth-to-mouth ventilation any better than no ventilation at all? Third, are other techniques of ventilation as effective or more effective than mouth-to-mouth ventilation during basic life support CPR? Although research is still inconclusive with regard to the need for ventilation during CPR,



recent findings have clarified the effect of ventilation during low blood flow states and how ventilation influences resuscitation. Ventilation affects oxygenation, carbon dioxide elimination, and pH during times of low rates of blood flow. Ventilation may be unnecessary during the first few minutes of CPR. Under conditions of prolonged, untreated cardiac arrest, ventilation during CPR affects return of spontaneous circulation. Isolated hypoxemia and hypercarbia independently have adverse effects on survival of cardiac arrest. Because ventilation with exhaled gas contains as much as 4% CO2 and less oxygen than air, it may have adverse effects during CPR. Spontaneous gasping may provide sufficient ventilation during CPR. Chest compression alone provides some pulmonary ventilation and gas exchange. Active chest compression-decompression may improve gas exchange better than does standard chest compression. Other forms of manual ventilation may also have a role in CPR.Not included in table.Comments: Level 7, Review of Literature, Supportive. Looked at the necessity of ventilation during CPR. Ventilation may be unnecessary during the first few minutes of CPR.

Jawan (2000) Jawan, B., Z. K. Chong, et al. (2000). "Aspiration in chest compression alone without mechanical ventilation in the head down position in dogs." Resuscitation 45(2): 133-8.

BACKGROUND: Previous work by the authors has shown that chest compressions alone without mechanical ventilation during cardiopulmonary resuscitation in the natural supine position was associated with pulmonary aspiration in dogs. The purpose of this investigation was to test the hypothesis that a head down position may prevent aspiration during chest compressions alone and whether oxygenation can be improved by simply insufflation of oral oxygen 10 min after cardiac arrest. METHODS: Cardiac arrest was induced in ten mongrel dogs which were anesthetized and paralysed. Eight underwent chest compressions alone in different head down positions using an automatic compressor at 9 kg compression force and 3 cm compression depth. The study was composed of two parts. Part 1 evaluated the effect of insufflation of 10 l/min O2, into the mouth of the dogs, 10 min after initiation of resuscitation, using chest compressions alone. Part 2 was designed to test our hypothesis that the head down position may protect the lungs from aspiration during chest compression alone. The mouths of the dogs were filled with mixed barium and the dogs underwent serial episodes of chest compressions, for 10 min each, in the 20 degree head down, 10 degree head down and the natural supine positions. Chest X-rays with antero-posterior and lateral views were taken to evaluate pulmonary aspiration. Two additional dogs underwent direct chest compression alone in the natural supine position and the time of chest compression was shortened to 5 min. RESULTS: All dogs in the natural position showed evidence of



pulmonary aspiration of barium, five or six of the dogs showed tracheal aspiration in the 10 degree head down position, while no any barium was visualized in the tracheo-broncheal trees of the dogs in the 20 degree head down position. Supplemental oxygen in the mouth improved the mean PaO2 from 67 +/- 26 to 160 +/- 97 mmHg during chest compressions alone. CONCLUSION: Chest compression alone without mechanical ventilation in the supine position caused pulmonary aspiration in the unprotected airway in dogs. This complication could be prevented by adopting a 20 degree head down position. The 10 degree head down position seemed to reduce the severity of the pulmonary aspiration, but not enough to eliminate the danger altogether. Supplemental oxygen in the mouth can improve oxygenation in chest compressions alone.Comments: Level 6, Fair, Neutral. Anesthetised, paralysed canine model of VF in which CPR (Chest compressions alone in different head-down positions) was instituted after 2 min of VF and continued for 10 min. Chest compressions without mechanical ventilation in the supine position causes pulmonary aspiration if the airway is unprotected.

Kern (2000) Kern, K. B. (2000). "Cardiopulmonary resuscitation without ventilation." Crit Care Med 28(11 Suppl): N186-9.

Current resuscitation methods, although occasionally effective, rarely perform as well as initially anticipated. Some of the disappointment can be attributed to the difficulty of the task for many, including both professional and lay first responders. Significant attention has been paid recently to the need to simplify both the technique and the teaching of resuscitation. In considering simplification of the current resuscitation scheme, a logical start is an honest reappraisal of the importance and priorities of each of the once sacrosanct ABCs, specifically, establishment of an Airway, artificial Breathing (mouth-to-mouth breathing), and chest compressions for temporary Circulation. Experimental data continue to accumulate indicating that most important within this triad is circulation. Adequate oxygen exists within the blood during at least the first 10 mins of cardiac arrest. If circulation is provided to distribute such oxygen, no survival disadvantage results with chest compression-only basic life support (BLS) efforts. Even a totally occluded airway during the first 6 mins of cardiac arrest does not compromise survival if reasonable circulation is provided with chest compressions. Clinical studies support the same conclusion that what most influences survival in any BLS effort is circulation, not ventilation. Belgium investigators have shown equal survival rates among those treated with chest compressions plus ventilation and those who received chest compressions alone. Telephone dispatcher-guided BLS cardiopulmonary resuscitation (CPR) has likewise shown no survival disadvantage to chest compression-only CPR when compared with telephone-guided standard BLS CPR. Based



on this reasoning, a new simplified BLS method has been proposed. "Staged" CPR consists of a strategy to initially teach laypersons a simplified approach to BLS, which requires only chest compressions and not mouth-to-mouth breathing. "Bronze" CPR, in which chest compression-only BLS is taught, was compared with the standard European Resuscitation Council BLS course for laypersons. Manikin "exit testing" at course completion has revealed significant advantages of the simplified approach compared with standard CPR courses for the lay public.Not included in table.Comments: Level 7, Review of Literature, Supportive. Reappraisal of the ABC’s in resuscitation. Experimental data indicates that the most important is circulation. Clinical studies show that circulation, and not ventilation, most influences survival in BLS.

Korte (2000) Korte, M. J. and J. J. Stevermer (2000). "Does the addition of mouth-to-mouth ventilation to chest compressions improve survival in bystander treatment of cardiac arrest?" J Fam Pract 49(8): 686-7Comments: Level 7, Review of Hallstrom (2000), Good, Supportive. See comments under Hallstrom (2000).

Krischer (1989) Krischer, J. P., E. G. Fine, et al. (1989). "Comparison of prehospital conventional and simultaneous compression-ventilation cardiopulmonary resuscitation." Crit Care Med 17(12): 1263-9.

Nine hundred ninety-four patients were enrolled in a field trial in which ambulance crews were randomly assigned to use simultaneous compression-ventilation (SC-V) CPR or conventional CPR procedures in the prehospital setting. Survival to hospital admission and to discharge was superior in the conventional CPR group vs. the experimental group (p less than .01). In a subset of adult cases whose causes of arrest were nontraumatic, survivor rates still favored the conventional CPR group: 33.5% of 337 vs. 22.5% of 365 (p less than .001). In limited cases where cardiac arrest was due to other heart disease, was vascular in origin or secondary to other natural diseases or from hypertensive cardiovascular disease, or when ECG on arrival was an agonal rhythm, survival was better (but not statistically significantly) in the experimental group. There were no statistically significant differences in the Glasgow coma scores between surviving patients in either group at 24 h post-hospital admission or discharge. It is concluded that survival in the SC-V CPR group was lower, likely reflecting a deleterious effect of the experimental technique of resuscitation. Also noted was that 14% of the control patients and 6% of the experimental patients survived with manual CPR alone.Not included in table.Comments: Level 7 (LOE 3 for SV-CPR vs conventional CPR), Fair, Neutral. Compares pre-hospital conventional CPR to Simultaneous Compression-Ventilation (SC-V) CPR in which survival to hospital admission and to discharge was superior in the conventional CPR



group.Noc (1994) Noc, M., M. H. Weil, et al. (1994). "Spontaneous gasping during

cardiopulmonary resuscitation without mechanical ventilation." Am J Respir Crit Care Med 150(3): 861-4.

Spontaneous gasping is frequently observed during cardiac arrest, especially when mechanical ventilation is withheld during precordial compression. We related spontaneous gasping to pulmonary gas exchange and cardiac resuscitability in a rodent model of cardiac arrest. Ventricular fibrillation was electrically induced in 15 Sprague-Dawley rats. After 4 min untreated ventricular fibrillation, precordial compression was initiated. Coronary perfusion pressure was maintained between 25 and 30 mm Hg. Oxygen was supplied at the tracheal tube port coincident with start of precordial compression in 10 animals. Five additional control animals were identically treated except they were mechanically ventilated coincident with start of precordial compression. After 6 min precordial compression, defibrillation was attempted and five of 10 nonventilated animals, and all control animals, were resuscitated by direct current countershock. In the successfully resuscitated, nonventilated animals, the frequency of spontaneous gasping during precordial compression progressively increased to an average of 19 gasps/min but it was < 6 gasps/min in nonresuscitated animals. More frequent gasping was associated with correspondingly greater arterial PO2 (110 versus 51 mm Hg, p < 0.01) and lesser PCO2 (55 versus 91 mm Hg, p < 0.01). In control animals, no spontaneous gasping was observed during precordial compression. Arterial PO2 and PCO2 of mechanically ventilated animals was more like that of spontaneously gasping rats. According, the frequency of spontaneous gasping in absence of mechanical ventilation is predictive of cardiac resuscitation success and associated with improved arterial oxygenation and CO2 removal.Comments: Level 6, Fair, Neutral. Anesthetised, intubated rodent model of VF in which precordial compressions was instituted ater 4 min of VF (ventilated and non-ventilated) and continued for 6 min when defibrillation was attempted. 50% of the non-ventilated versus 100% of the ventilated rodents were successfully resuscitated. In those successfully resuscitated non-ventilated rodents, spontaneous gasping was approx 19 gasps/min and associated with greater PaO2 and lesser PaCO2, similar to that of the mechanically ventilated rodents.

Sigurdsson (2003) Sigurdsson, G., D. Yannopoulos, et al. (2003). "Cardiorespiratory interactions and blood flow generation during cardiac arrest and other states of low blood flow." Curr Opin Crit Care 9(3): 183-8.

PURPOSE OF REVIEW: Recent advances in cardiopulmonary resuscitation have shed light on the importance of cardiorespiratory interactions during shock and cardiac arrest. This review focuses on recently published studies that evaluate



factors that determine preload during chest compression, methods that can augment preload, and the detrimental effects of hyperventilation and interrupting chest compressions. RECENT FINDINGS: Refilling of the ventricles, so-called ventricular preload, is diminished during cardiovascular collapse and resuscitation from cardiac arrest. In light of the potential detrimental effects and challenges of large-volume fluid resuscitations, other methods have increasing importance. During cardiac arrest, active decompression of the chest and impedance of inspiratory airflow during the recoil of the chest work by increasing negative intrathoracic pressure and, hence, increase refilling of the ventricles and increase cardiac preload, with improvement in survival. Conversely, increased frequency of ventilation has detrimental effects on coronary perfusion pressure and survival rates in cardiac arrest and severe shock. Prolonged interruption of chest compressions for delivering single-rescuer ventilation or analyzing rhythm before shock delivery is associated with decreased survival rate. SUMMARY: Cardiorespiratory interactions are of profound importance in states of cardiovascular collapse in which increased negative intrathoracic pressure during decompression of the chest has a favorable effect and increased intrathoracic pressure with ventilation has a detrimental effect on survival rate.Not included in table.Comments: Level 7, Review of Literature, Supportive. Importance of cardiorespiratory interactions during shock and cardiac arrest. Prolonged interruption of chest compressions for delivering single-rescuer ventilation or analyzing rhythm before shock delivery is associated with decreased survival.

Weil (1997) Weil, M. H. (1997). "Research on CPR: reordering priorities." New Horiz 5(2): 106-11.

The "ABCs" of CPR, i.e., airway, breathing, and circulation, represent the sequence of interventions currently advised and taught to providers of both basic life support (BLS) and advanced life support (ALS) by the American Heart Association. Nevertheless, in the settings of suspected or confirmed ventricular fibrillation, the ABCs may be deferred such that external electrical countershock(s) take(s) precedence. However, efforts to restore circulation by chest compression (or alternative mechanical means) remain the lowest of the three priorities for both BLS and ALS as presently prescribed. This ordering of priorities is based largely on the consensus rather than objective experimental or clinical evidence of improved outcomes. During the last 5 yrs, both clinical and experimental studies demonstrated that the A and B of these ABCs, and specifically positive-pressure ventilation, may not be essential during the initial 6 to 12 mins of CPR under conditions of sudden dysrhythmic cardiac arrest and in the absence of asphyxia. Recent studies further suggested that either or both precordial



compression and spontaneous gasping may of itself generate sufficient alveolar ventilation during the initial 6 mins of CPR. Defibrillation now emerges as the highest priority. Automated defibrillators have a pivotal role. The need for objective controlled research, including experience with devices in clinical settings and technical improvements of operation, are essential.Not included in table.Comments: Level 7, Review of Literature, Supportive. Clincal and experimental studies have shown that during initial 6-12 min of CPR the A & B (of the ABC’s) may not be essential.

Wolcke (2003) Wolcke, B. B., D. K. Mauer, et al. (2003). "Comparison of standard cardiopulmonary resuscitation versus the combination of active compression-decompression cardiopulmonary resuscitation and an inspiratory impedance threshold device for out-of-hospital cardiac arrest." Circulation 108(18): 2201-5.

BACKGROUND: Active compression-decompression (ACD) CPR combined with an inspiratory impedance threshold device (ITD) improves vital organ blood flow during cardiac arrest. This study compared survival rates with ACD+ITD CPR versus standard manual CPR (S-CPR). METHODS AND RESULTS: A prospective, controlled trial was performed in Mainz, Germany, in which a 2-tiered emergency response included early defibrillation. Patients with out-of-hospital arrest of presumed cardiac pathogenesis were sequentially randomized to ACD+ITD CPR or S-CPR by the advanced life support team after intubation. Rescuers learned which method of CPR to use at the start of each work shift. The primary end point was 1-hour survival after a witnessed arrest. With ACD+ITD CPR (n=103), return of spontaneous circulation and 1- and 24-hour survival rates were 55%, 51%, and 37% versus 37%, 32%, and 22% with S-CPR (n=107) (P=0.016, 0.006, and 0.033, respectively). One- and 24-hour survival rates in witnessed arrests were 55% and 41% with ACD+ITD CPR versus 33% and 23% in control subjects (P=0.011 and 0.019), respectively. One- and 24-hour survival rates in patients with a witnessed arrest in ventricular fibrillation were 68% and 58% after ACD+ITD CPR versus 27% and 23% after S-CPR (P=0.002 and 0.009), respectively. Patients randomized > or =10 minutes after the call for help to the ACD+ITD CPR had a 3 times higher 1-hour survival rate than control subjects (P=0.002). Hospital discharge rates were 18% after ACD+ITD CPR versus 13% in control subjects (P=0.41). In witnessed arrests, overall neurological function trended higher with ACD+ITD CPR versus control subjects (P=0.07). CONCLUSIONS: Compared with S-CPR, ACD+ITD CPR significantly improved short-term survival rates for patients with out-of-hospital cardiac arrest. Additional studies are needed to evaluate potential long-term benefits of ACD+ITD CPR.Not included in table.Comments: Level 7 (LOE 2 for S-CPR vs ACD+ITD CPR), Good, Neutral. Prospective, randomized, controlled trial in which



patients (who were intubated during their arrest) received either standard CPR or ACD + ITD (Active compression-decompression + Inspiratory impedance threshold device) CPR during out-of-hospital cardiac arrest. CPR (whether S-CPR or ACD + ITD CPR) was provided for 30 min or until palpable pulse. Significant short-term survival benefit was shown in the ACD + ITD CPR group compared to the S-CPR group.

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