Journal of Sleep Medicine & Disorders

Cite this article: West SD, Littlemore J, Oliver J, Close PR, Thirugnanasothy L (2017) Predicting Who Needs A Humidifier with Continuous Positive Airway Pressure (CPAP) – A Prospective Cohort Study. J Sleep Med Disord 4(2): 1078.

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*Corresponding authorNewcastle Regional Sleep Service, Newcastle upon Tyne Hospitals NHS Trust, NE7 7DN, UK, Tel: 0044 191 223 6161; Fax: 0044 191 2137397; Email:

Submitted: 10 May 2017

Accepted: 29 June 2017

Published: 30 June 2017

ISSN: 2379-0822

Copyright© 2017 West et al.

OPEN ACCESS

Keywords•Sleepapnea;CPAP;Humidifiers;Nasalsteroids

Research Article

Predicting Who Needs A Humidifier with Continuous Positive Airway Pressure (CPAP) – A Prospective Cohort StudyWest SD*, Littlemore J, Oliver J, Close PR, and Thirugnanasothy LNewcastle Regional Sleep Service, Newcastle upon Tyne Hospitals NHS Trust, UK

Abstract

Background: It is unclear which patients commencing continuous positive airway pressure (CPAP) for symptomatic Obstructive Sleep Apnoea (OSA) will need heated humidification. We sought to establish in a UK Sleep clinic whether there were any prospective patient predictors for humidification, as it would be more cost effective to provide CPAP with an integrated heated humidifier in those people, than a separate heated humidifier later; any humidification is more costly than none.

Methods: We completed a questionnaire in consecutive patients commencing CPAP over a one year period at the time of out-patient CPAP set-up.The questionnaire asked about symptoms present prior to CPAP commencement, including blocked, dry or runny nose and dry mouth on waking, medication history, including the use of anti-histamines and nasal sprays and smoking history. Previous ear nose and throat surgery, co-existent respiratory disease and diabetes were recorded. Heated humidifiers were provided at CPAP reviews as required based on symptoms, as per usual practice. Questionnaire responses were analysed with Chi Square analysis to determine whether any variables predicted later heated humidifier requirement.

Results: There were 185 completed questionnaires: the mean age was 53 years (SD 11.7), mean body mass index 36.6 kg/m2 (SD 7.1), mean neck size 43.9cm (SD 4.4). The mean ODI was 29.3 per hour (SD 23.1). In this group, 47% had severe OSA, 34% had moderate OSA and 19% had mild OSA, representing a typical Sleep clinic population. There were 67 people (43%) given a heated humidifier after CPAP initiation for symptoms. There were no statistically significant correlations of any of the questionnaire variables with heated humidifier issue. Chi squared analysis showed no significant difference in the proportion of those people with a humidifier versus those without for any of the questionnaire or ODI categories.

Conclusion: We recommend that a symptom-led approach to heated humidifier provision with CPAP for OSA appears valid and may be economical depending on the health care setting, rather than providing integrated humidifier units to all.

INTRODUCTIONContinuous positive airway pressure (CPAP) is a widely used

for the treatment of people with symptomatic significant Ob-structive Sleep Apnoea (OSA). Some patients using CPAP have upper airway symptoms, such as dry nose and mouth, blocked nose, which may reduce comfort and limit CPAP adherence. Sleep clinics frequently provide a heated humidifier for use with CPAP for patients experiencing these symptoms, with the aim of allevi-ating them and facilitating ongoing CPAP use. Studies have shown that humidifiers used with CPAP are effective at increasing the relative humidity of inspired air and reducing the water loss dur-ing respiration [1], along with demonstrating high humidification in the distal CPAP tube [2], suggesting this technique is suitable for the treatment of dry upper airways caused by CPAP therapy.

Centres have tried to determine which patients will benefit most from humidification with CPAP. One prospective study of 82 people commencing CPAP for OSA, aimed to identifies potential risk factors predicting the need for additional humidification to CPAP [3]. They provided humidifiers to 56% of patients after a median time of 39 days (range 2 to 94 days). The results showed

that age greater than 60, drying medications, chronic mucosal disease symptoms and previous uvulopalatopharyngoplasty (UPPP) were statistically significant risk factors for needing heated humidification.

We sought to establish in a larger UK Sleep clinic cohort whether there were any prospective patient predictors for whether a heated humidifier would subsequently be needed after starting CPAP. This might allow provision of more economic integrated CPAP machines with inbuilt humidifiers, rather than using two separate CPAP and humidifier units which are more costly in our health-care setting.

METHODSWe aimed to include consecutive patients commencing CPAP

for symptomatic significant OSA over a one year period who would complete a questionnaire with a member of the Sleep team at the time of out-patient CPAP set-up. The questionnaire asked about symptoms present prior to CPAP commencement, including blocked, dry or runny nose and dry mouth on waking. Age of house and whether people slept with heating on or window

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open were collected. Medication history, including the use of anti-histamines and nasal sprays and smoking history was taken. Previous ear nose and throat surgery, co-existent respiratory disease and diabetes were recorded.

The 4% Oxygen desaturation index (ODI), apnea-hypopnoea index (AHI) body mass index (BMI) and neck circumference were obtained from hospital clinic notes. The ODI and AHI were obtained following multichannel respiratory polygraphy (Embletta, Flaga). The study was reviewed by a sleep consultant who had details of the patient’s clinical symptoms and a decision about whether CPAP was indicated or not was made. No patient was given a heated humidifier at commencement of CPAP, as is our usual practice. Patients were given heated humidifiers according to usual practice as required after CPAP commencement, according to nasal and mouth symptoms on routine review, usually at one month after commencement of CPAP. The CPAP database was reviewed at the end of the study to determine which patients had received humidifiers; this was 6 months to a year after all patients had commenced CPAP. A p value of <0.05 was considered to be statistically significant. Analysis was performed with SPSS version 22 (IBM Corp, USA). Independent t tests were performed to compare baseline characteristics of those people who later received a humidifier versus those who did not. Chi squared analysis was performed to investigate the proportion of those people with a heated humidifier versus those without for any of the questionnaire or ODI categories.

RESULTSThe study took place between January to December 2012.

Over this time period, 185 patients completed questionnaires prior to commencing CPAP. In this time period, there were a total of 541 people commencing CPAP, so this represents a sample of 34%.Those people who did not complete questionnaires were those who in whom there was not sufficient clinic time to allow questionnaire completion. Of those who completed

questionnaires, the baseline anthropometric characteristics are shown in Table 1. In this group, 47% had severe OSA with ODI of greater than 20 per hour, 34% had moderate OSA with an ODI of 10-19 per hour and 19% had mild OSA with ODI of less than 10 per hour. This represents a typical Sleep clinic population, with a spread of OSA severity. There were no significant differences in any of the baseline characteristics of those people who later received a humidifier versus those who did not.

There were 67 people (43%) given a heated humidifier after CPAP initiation because of symptoms. Chi squared analysis showed no significant difference in the proportion of those people with a humidifier versus those without for any of the questionnaire or ODI categories (Table 2). There were no statistically significant correlations of any of the questionnaire variables with humidifier outcome.

DISCUSSIONIn this prospective study of 185 people commencing CPAP

for OSA, we were unable to determine any anthropometric, sleep study or questionnaire feature which differentiated those patients who needed a humidifier for symptoms of dry mouth or dry nose from those who did not. It does not appear to be possible to prospectively predict which patients will require a humidifier with CPAP, even with specific detailed questioning about possible risk factors. Therefore the current practice of symptom-led humidification appears valid. Providing integrated humidification systems with CPAP at initiation would appear not to offer any economic advantages in our setting.

In this study, we were unable to perform questionnaires on all consecutive patients commencing CPAP in our centre, due to time constraints in the clinic on occasion. We did not collect data on those who did not complete questionnaires, but they were unlikely to have different characteristics from the studied group; their non inclusion was random but it does mean we did not have a complete consecutive sample as we had originally intended.

Table 1: Baseline characteristics of group and according to whether or not they received a heated humidifier for symptoms. Data are presented as mean (SD). ODI =4% Oxygen desaturation index per hour, AHI = apnea hypopnea index per hour, BMI= body mass index. N.s. = not significant

All Humidifier No humidifier p

Age 53.4 (11.7) 52.8 (11.8) 54.3 (11.3) n.s.

ODI 29.0 (23.1) 28.0 (22.1) 29.3 (23.3) n.s.

AHI 32.7 (27.1) 33.5 (28.8) 45.6 (29.6) n.s.

BMI kg/m2 36.5 (7.1) 36.3 (6.8) 36.8 (7.4) n.s.

Neck circumference, cm 43.9 (4.4) 44.0 (4.6) 43.8 (4.3) n.s.

CPAP pressure, cm H20 10.4 (1.9) 10.5 (2.2) 10.2 (1.7) n.s.

Table 2: Questionnaire variables pre CPAP according to whether or not they received a heated humidifier for symptoms. Data are presented as percentages of total.

Humidifier No humidifier pCurrent smoker: 36% 35% n.s.

Diabetes 16% 19% n.s.Any previous ear, nose or throat surgery 68% 70% n.s.

Blocked nose 53% 53% n.s.Dry nose 43% 40% n.s.

Runny nose 20% 27% n.s.Dry mouth 91% 85% n.s.

No history of any respiratory disease 35% 31% n.s.

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These results differ from those of the previously quoted study [3]. They had a smaller study population, but provided humidification to a higher proportion of the patients. There is no doubt a subjective element to humidifier provision as there is no scale for measuring symptoms of nasal or mouth dryness and nasal stuffiness. Previous humidifier success with a patient may influence future humidifier prescription by a health care professional. The differences in proportions having humidifiers may have led to the positive associations with predictive variables in their cohort.

Other studies in this area have sought to establish whether patient comfort and CPAP adherence are improved with prophylactic humidification; there are mixed results. Clearly a randomised controlled trial design is the gold standard to answer this question. In general, although nasal symptoms improve with humidification, CPAP compliance is unchanged. Wiest et al., gave 44 patients a crossover of one night of CPAP alone and one night of CPAP with humidification on their first two nights [4]. Both treatments gave 75% of patients a better night than without CPAP. Nineteen patients (43%) gave preference to treatment with a humidifier for long-term use, while 25 patients (57%) had no preference or said they would prefer treatment without humidification.

Ruhle et al., randomised 44 different patients to two initial nights on CPAP with either heated humidification or not, monitored by polysomnography [5]. Sleep parameters measured in the sleep laboratory did not differ significantly between these two nights, although dry mouth was significantly decreased with humidification and coldness of the face was also decreased. Waking with wetness of face was significantly increased. They were then randomised to receive one of the treatment modalities at home for four weeks. Quality of life and compliance measured after four weeks was not different between the two groups, but nasopharyngeal dryness, however, was reduced during the first weeks of treatment with humidification.

Similar results were found in another study of 52 people randomised to CPAP or CPAP plus humidifier [6]. The humidifier group had significantly improved nasopharyngeal symptoms, but did not have any benefit in further willingness to use CPAP and in sleep improvement, suggesting routine humidifier use is not beneficial.

By contrast, Massie et al showed CPAP adherence was enhanced by heated humidification [7]. The authors recommended starting heated humidification at CPAP initiation following a randomised cross over study of 38 patients with OSA.CPAP use with heated humidity (5.52+/-2.1 h/night) was greater than CPAP use without humidity (4.93+/-2.2 h/night; p = 0.008). Specific side effects such as dry mouth or throat and dry nose were reported less frequently when CPAP was used with heated humidity (p<0.001).

Finally Ryan et al randomised 125 people commencing CPAP to four weeks of dry CPAP, humidified CPAP or CPAP with additional topical nasal steroid application (fluticasone, GlaxoWellcome) [8]. There was no difference in compliance,

subjective sleepiness or quality of life between groups after four weeks. Nasal symptoms were less frequently reported in the humidifier group (28%) than in the remaining groups (dry: 70%, fluticasone: 53%, p = 0.002). The addition of fluticasone resulted in increased frequency of sneezing.

CONCLUSIONOur prospective cohort study found no questionnaire patient

predictors which can be utilised in our setting to predict who will benefit from prophylactic humidification for nasal symptoms with CPAP. The literature supports this and shows there is no benefit in providing humidifiers for all patients commencing CPAP. Humidifiers do decrease nasal symptoms and in one study improved CPAP adherence. We recommend therefore that a symptom led approach to humidifier provision with CPAP for OSA appears valid and may be economical depending on the costs in the health care setting of providing integrated humidified CPAP versus separate CPAP and humidifier units.

AUTHOR CONTRIBUTIONSW, JL designed the study. JL, JO, PC were all involved in

clinical care of patients, questionnaire completion and provision of humidifiers where indicated. JL and LT analysed the data at the end of the study. SW wrote the paper.

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West SD, Littlemore J, Oliver J, Close PR, Thirugnanasothy L (2017) Predicting Who Needs A Humidifier with Continuous Positive Airway Pressure (CPAP) – A Prospective Cohort Study. J Sleep Med Disord 4(2): 1078.

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