P380 Comparison between fixed an automatic continuous positive airway pressure (CPAP) in patients with nose problems after starting treatment with CPAP

Pressure modification or humidification for improving usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is the repetitive closure of the upper airway during sleep. This results in disturbed sleep and excessive daytime sleepiness. It is a risk factor for long-term cardiovascular morbidity. Continuous positive airway pressure (CPAP) machines can be applied during sleep. They deliver air pressure by a nasal or oronasal mask to prevent the airway from closing, reducing sleep disturbance and improving sleep quality. Some people find them difficult to tolerate because of high pressure levels and other symptoms such as a dry mouth. Switching to machines that vary the level of air pressure required to reduce sleep disturbance could increase comfort and promote more regular use. Humidification devices humidify the air that is delivered to the upper airway through the CPAP circuit. Humidification may reduce dryness of the throat and mouth and thus improve CPAP tolerability. This updated Cochrane Review looks at modifying the delivery of positive pressure and humidification on machine usage and other clinical outcomes in OSA.

OBJECTIVES

To determine the effects of positive pressure modification or humidification on increasing CPAP machine usage in adults with OSA.

SEARCH METHODS

We searched Cochrane Airways Specialised Register and clinical trials registries on 15 October 2018.

SELECTION CRITERIA

Randomised parallel group or cross-over trials in adults with OSA. We included studies that compared automatically adjusting CPAP (auto-CPAP), bilevel positive airway pressure (bi-PAP), CPAP with expiratory pressure relief (CPAPexp), heated humidification plus fixed CPAP, automatically adjusting CPAP with expiratory pressure relief, Bi-PAP with expiratory pressure relief, auto bi-PAP and CPAPexp with wakefulness detection with fixed pressure setting.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. We assessed the certainty of evidence using GRADE for the outcomes of machine usage, symptoms (measured by the Epworth Sleepiness Scale (ESS)), Apnoea Hypopnoea Index (AHI), quality of life measured by Functional Outcomes of Sleep Questionnaire (FOSQ), blood pressure, withdrawals and adverse events (e.g. nasal blockage or mask intolerance). The main comparison of interest in the review is auto-CPAP versus fixed CPAP.

MAIN RESULTS

We included 64 studies (3922 participants, 75% male). The main comparison of auto-CPAP with fixed CPAP is based on 36 studies with 2135 participants from Europe, USA, Hong Kong and Australia. The majority of studies recruited participants who were recently diagnosed with OSA and had not used CPAP previously. They had excessive sleepiness (ESS: 13), severe sleep disturbance (AHI ranged from 22 to 59), and average body mass index (BMI) of 35 kg/m2. Interventions were delivered at home and the duration of most studies was 12 weeks or less. We judged that studies at high or unclear risk of bias likely influenced the effect of auto-CPAP on machine usage, symptoms, quality of life and tolerability, but not for other outcomes. Primary outcome Compared with average usage of about five hours per night with fixed CPAP, people probably use auto-CPAP for 13 minutes longer per night at about six weeks (mean difference (MD) 0.21 hours/night, 95% confidence interval (CI) 0.11 to 0.31; 31 studies, 1452 participants; moderate-certainty evidence). We do not have enough data to determine whether auto-CPAP increases the number of people who use machines for more than four hours per night compared with fixed CPAP (odds ratio (OR) 1.16, 95% CI 0.75 to 1.81; 2 studies, 346 participants; low-certainty evidence). Secondary outcomes Auto-CPAP probably reduces daytime sleepiness compared with fixed CPAP at about six weeks by a small amount (MD -0.44 ESS units, 95% CI -0.72 to -0.16; 25 studies, 1285 participants; moderate-certainty evidence). AHI is slightly higher with auto-CPAP than with fixed CPAP (MD 0.48 events per hour, 95% CI 0.16 to 0.80; 26 studies, 1256 participants; high-certainty evidence), although it fell with both machine types from baseline values in the studies. Ten per cent of people in auto-CPAP and 11% in the fixed CPAP arms withdrew from the studies (OR 0.90, 95% CI 0.64 to 1.27; moderate-certainty evidence). Auto-CPAP and fixed CPAP may have similar effects on quality of life, as measured by the FOSQ but more evidence is needed to be confident in this result (MD 0.12, 95% CI -0.21 to 0.46; 3 studies, 352 participants; low-certainty evidence). Two studies (353 participants) provided data on clinic-measured blood pressure. Auto-CPAP may be slightly less effective at reducing diastolic blood pressure compared to fixed CPAP (MD 2.92 mmHg, 95% CI 1.06 to 4.77 mmHg; low-certainty evidence). The two modalities of CPAP probably do not differ in their effects on systolic blood pressure (MD 1.87 mmHg, 95% CI -1.08 to 4.82; moderate-certainty evidence). Nine studies (574 participants) provided information on adverse events such as nasal blockage, dry mouth, tolerance of treatment pressure and mask leak. They used different scales to capture these outcomes and due to variation in the direction and size of effect between the studies, the comparative effects on tolerability outcomes are uncertain (very low-certainty evidence).  The evidence base for other interventions is smaller, and does not provide sufficient information to determine whether there are important differences between pressure modification strategies and fixed CPAP on machine usage outcomes, symptoms and quality of life. As with the evidence for the auto-CPAP, adverse events are measured disparately.

AUTHORS' CONCLUSIONS

In adults with moderate to severe sleep apnoea starting positive airway pressure therapy, auto-CPAP probably increases machine usage by about 13 minutes per night. The effects on daytime sleepiness scores with auto-CPAP are not clinically meaningful. AHI values are slightly lower with fixed CPAP. Use of validated quality of life instruments in the studies to date has been limited, although where they have been used the effect sizes have not exceeded proposed clinically important differences. The adoption of a standardised approach to measuring tolerability would help decision-makers to balance benefits with harms from the different treatment options available. The evidence available for other pressure modification strategies does not provide a reliable basis on which to draw firm conclusions. Future studies should look at the effects of pressure modification devices and humidification in people who have already used CPAP but are unable to persist with treatment.

Pressure modification for improving usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea

BACKGROUND

Continuous Positive Airways Pressure (CPAP) is considered to be the cornerstone of therapy for obstructive sleep apnoea (OSA). However, compliance with this treatment is frequently poor, which may lead to ongoing symptoms of sleep disruption, daytime sleepiness and poor waking cognitive function. Mechanical interventions which involve changing the way that positive pressure is delivered, and the addition of humidification, might improve compliance.

OBJECTIVES

To determine the efficacy of pressure level modifications and additional humidification in increasing CPAP machine usage.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register (September 2008).

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing interventions to improve compliance with CPAP usage. Control groups received fixed pressure CPAP.

DATA COLLECTION AND ANALYSIS

Two authors assessed articles for inclusion in the review and extracted data. We made attempts to obtain additional unpublished data from the trialists.

MAIN RESULTS

Forty-five studies met the inclusion criteria (1874 participants). Auto-CPAP (30 studies, 1136 participants): a statistically significant difference in machine usage of 0.21 hours/night (0.08 to 0.35) was observed in favour of auto-CPAP from cross-over studies. This difference is of questionable clinical significance. Pooled effect estimates from parallel group trials detected a similar sized difference for average nightly machine usage, but this was not statistically significant. Evidence from parallel group studies did not identify a statistically significant difference between pressure modes in Epworth Sleepiness Scores, but there was an overall reduction of 0.64 units with cross-over studies (-0.12 to -1.16) in favour of auto-CPAP. Parallel group studies did not identify a significant difference. More participants preferred auto-CPAP to fixed CPAP where this was measured. Bi-level PAP (six studies, 285 participants): no significant differences were observed in machine usage. One small study found no difference in preference. C-Flex (six studies, 318 participants): no significant difference was observed in machine usage. Humidification (three studies, 135 participants): there were conflicting findings between the studies. Two parallel group trials found no significant difference in machine usage, whereas a cross-over study found a significant difference.

AUTHORS' CONCLUSIONS

Improvement in average machine use of auto-CPAP was superior in studies with a cross-over design; the point estimate in parallel group trials was similar, but did not reach statistical significance. It is uncertain how use of machines in study settings relates to 'real world' use. Where preference was measured participants preferred auto-CPAP to fixed pressure CPAP. Further studies are required to assess the evidence for Bi-PAP, C-Flex(TM) and humidification. The studies assembled were characterised by high machine usage in the control groups, and low withdrawal rates. Future studies need to consider the effects of treatment in participants with more mild disease, and those who struggle to accept therapy despite persistent symptoms.