Objective Measurement of Patterns of Nasal CPAP Use by Patients with Obstructive Sleep Apnea

The following information is provided by: Fisher & Paykel Healthcare

By Dr. Vanessa MB Jordan Ph.D., Research Scientist, Fisher & Paykel Healthcare

N.B. Kribbs, A.I. Pack, L.R. Kline, P.L. Smith, A.R. Schwartz, N.M. Schubert, S. Redline, J.N. Henry, J.E. Getsy and D.F. Dinges
Am Rev Respir Dis 1993; 147(4): 887-895

Key Points

• Patients when self-reporting significantly overestimated the amount of time they used CPAP.
• Only 46% of participants could be considered regular users. That is > 4 hours per night for more than 70% of nights.
• One of most frequently cited problems was stuffy nose (46%).

Aim

To obtain objective evidence of the patterns of CPAP use.
To determine if actual use is less than prescribed and less than that reported by patients.

Method

42 patients recruited, 7 were excluded due to technical problems.

CPAP units had hidden monitoring equipment to determine CPAP use (able to distinguish when the machine was actually in use versus when power was switched on).

Pre-treatment questionnaire - assessed daytime sleepiness, patient demographics and ability to perform tasks.

Follow up Questionnaire - Measured self reported CPAP use, side effects, daytime sleepiness and ability to perform tasks.

Results

On average patients attempted to use CPAP for 66% of days for a mean duration of 4.88 hours.

For 9% of the time when the machine was on the mask was not being used.

The majority of use of the machines occurred between 10:00pm and 9:00am.

Patients use of CPAP did not significantly differ between months one and three. Therefore use of CPAP did not improve or alternatively did not worsen over time.

When patient reports of use were compared to actual use, as measured by the covert monitor, it was shown that they overestimated both the number of days as well as the number of hours on each day that they had used CPAP.

46% of patients were considered regular users that is they used CPAP for >4hours for more than 70% of nights.

When regular and non-regular users were compared, it was shown that regular users had more years of education and were more likely to be employed in professional type jobs. It is possible that the higher levels of concentration and the sedentary nature of professional jobs resulted in an increased identification of the benefits of CPAP.

There were no differences between regular users and non-regular users with regard to demographic data (race, age, marital status) or clinical data (respiratory disturbance index (RDI), multiple sleep latency test (MSLT)).

During follow up regular users were satisfied with their CPAP treatment and reported greater levels of daytime sleepiness.

There were no significant correlations between regular use of CPAP and baseline pre-treatment measures of apnea severity (RDI, O2 saturation) or the objective measure of sleepiness (MSLT).

Claustrophobia was the only side effect that discriminated between regular and non-regular users and that was claustrophobia.

The most frequently rated side effects were inconvenience and stuffy nose.

Conclusions

Using covert monitoring, it was shown that fewer than half of patients regularly use CPAP.

The severity of OSA did not influence whether or not a patient became a regular user.