Not Feeling Well Despite Using CPAP? Make Sure Your Machine is Working – a Study

Dr. Zhu and colleagues’ study published in this month’s Journal of Clinical Sleep Medicine (July 2015) showed the auto-titrating continuous positive airway pressure (CPAP) devices are inconsistent in treating obstructive sleep apnea. 

The study also raised a serious concern about the accuracy of the device compliance reports. These are the compliance reports that the sleep physician use to evaluate the treatment efficacy and to adjust the pressure on these machines.

Dr. Zhu and colleagues evaluated eleven commercially available CPAP devices on their reactions to obstructive apnea (cessation of respiration for 10 seconds or longer), hypopnea (abnormally shallow respirations), central apnea (cessation of respiration despite an open airway), and snoring.

Their results were startling.

In a single sequence of 30-minute repetitive obstructive apneas, only 5 devices normalized the airflow. Similarly, normalized breathing was recorded with 8 devices only for a 20-min obstructive hypopnea sequence.

Only five devices increased the pressure in response to snoring while only 4 devices maintained a constant minimum pressure when subjected to repeated central apneas with an open upper airway.

In the long general breathing scenario, the pressure responses and the treatment efficacy differed among devices: only 5 devices obtained a residual obstructive AHI < 5/h.

During the short general breathing scenario, only 2 devices reached the same treatment efficacy (p < 0.001), and 3 devices underestimated the Apnea Hypopnea Index by > 10% (p < 0.001). The long scenario led to more consistent device reports.


If the patient is not feeling better despite using CPAP, let us not blame the patient! Let us explore other options; change the CPAP machine, do an in-lab CPAP study, or do an in-office CPAP nap study.

Sleep Well, Live Well.

God Bless.