Intermittent hypoxia sensitizes control centers in the brain, noted Krishna M. Sundar, MD, clinical professor, Pulmonary Division, Department of Medicine, and medical director, Sleep-Wake Center, University of Utah.
Intermittent hypoxia sensitizes control centers in the brain, the result being exaggerated responses to even a minor change in breathing, noted Krishna M. Sundar, MD, clinical professor, Pulmonary Division, Department of Medicine, and medical director, Sleep-Wake Center, University of Utah.
How do the physiologies for obstructive and central sleep apnea overlap?
They overlap quite a bit, because each time there is a lack of the respiratory generator rhythm, which drives a breath, there is a pause in breathing because of a central apnea. So with each breath, it's not really that the diaphragm contracts and opens up the lung, the area has to be opened up also. So again, if there is no impulse to breathe, there is a tendency for the airway to narrow. A central sleep apnea can actually lead to airway collapse and obstruction. So that's one simplistic explanation.
The other thing is that in obstructive sleep apnea, we have a phenomenon called intermittent hypoxia, because oxygen levels keep fluctuating each time [the airway closes, reopens] when the patient wakes up, and then [closes] again as they drift into deep sleep. So this fluctuating oxygen levels sensitizes the control centers in the carotid body in the brain. And that can lead to something called an exaggerated response to any minor change in breathing, which may also cause some instability of breathing. Any instability of breathing at night, indeed, the more central apneas. So obstructive sleep apnea can lead to more central apneas, and central apneas lead to obstructive sleep apnea.
Again, practitioners need to understand what is driving what and what are the factors which [are] driving central sleep apnea in the [patients].