There’s so much more to obstructive sleep apnea than just dips in blood oxygen levels overnight, which is why supplemental oxygen is no match for CPAP.
CPAP Therapy vs. Supplemental Oxygen in Treating Obstructive Sleep Apnea
A study was carried out by Gottlieb et al and reported in the New England Journal of Medicine (June 2014).
Many people wonder why the cumbersome CPAP mask and hose system is the gold standard treatment, despite an unimpressive compliance rate, when supplemental oxygen via a simple nasal cannula would be so much more tolerable – while maintaining normal blood oxygen levels throughout the night.
The reason supplemental oxygen isn’t nearly as effective as CPAP is because it does nothing to prevent the airway collapses.
And it’s the airway collapses that really mess things up in the body.
CPAP does a wonderful job of normalizing blood pressure during sleep, preventing hypertension.
The Gottlieb study showed that supplemental oxygen did not reduce blood pressure.
However, the oxygen was expected to prevent hypertension because the intermittent periods of oxygen depletion (hypoxemia) triggers sustained rises in blood pressure.
There is no question that the supplemental oxygen’s effect on hypoxemia is quite comparable to that of CPAP.
Why didn’t supplemental oxygen prevent blood pressure spikes?
It’s related to the collapsed airways, which cause “large swings in intrathoracic pressure,” says the NEJM paper.
The paper also notes that there was an “absence of more detailed physiological measures,” and hence, “our ability to draw mechanistic inferences from these data is limited.”
Supplemental oxygen does not prevent the harmful changes in intrathoracic pressure that result from night-long breathing against resistance.
Your blood could have all the oxygen in the world from a supplemental device, but without CPAP, you’d still be inhaling against the resistance caused by the soft tissue of your throat caving into your airway.
It’s this breathing against resistance that sets off a chain of events that lead to blood pressure rises and, over time, damage to the cardiovascular system.
Of course, there’s no question that CPAP could prevent this damage.
The paper says that “treatment of obstructive sleep apnea with CPAP, but not with nocturnal supplemental oxygen, results in significant reduction in blood pressure, even in patients with well-controlled hypertension at baseline.
“Although there may be other clinical reasons a treating physician should consider using supplemental oxygen in specific patients, this study offers no support for the common but largely untested clinical practice of supplemental oxygen as salvage therapy in patients with obstructive sleep apnea for whom CPAP is problematic.”