CPAP in Airplanes article

[LindanHotAir]

The AOPA is the Aircraft Owners and Pilots Association.
In the December 2021 issue of AOPA Pilot magazine, Dr. Ben Blue, an aviation medical examiner in Driggs, Idaho wrote an article, CPAP in aircraft? A simple solution below 12,500 feet.
 He reports that many people experience periodic breathing at higher altitudes, and often experience some level of oxygen desaturation at altitude increases of 6000 feet from their home elevation. 
 The FAA rule about supplemental oxygen for any flights above 12,500 feet for 30 minutes was developed in the 1950s before pulse oximeters (or LEDs) were invented. It was a compromise to allow unpressurized aircraft to cross the Rocky Mountains for short times without an expensive supplemental oxygen system. Now a $20 pulse oximeter will give you an instant readout of your oxygen saturation to allow you to determine if you need to supplement your oxygen or air pressure at lower altitudes..
Dr. Blue recommends a CPAP or APAP for anyone who experiences desaturation at any altitude below 12,500 feet where the FAA mandates supplemental oxygen.

[RNeil]

I will read the article.
It sounds like it would not apply to most members of this forum because most of us only fly in commercial air liners that are pressurized.

[Sleeprider]

CPAP does not increase oxygen saturation, except by preventing obstructive sleep apnea during sleep which interferes with tidal volume, and minute vent rates. At any altitude where CPAP is deemed effective, it only increases airway differential pressure. It does not increase the fraction of inspired oxygen (FiO2), which is the role of supplemental oxygen. A higher positive end expiratory pressure (PEEP), can help to recruit lung volume, but in CPAP this effect does not overcome the impacts of altitude.

Looking at this from a more direct point of view, the atmospheric pressure at sea level is 14.70 psi or 1033.5 cm. A person using CPAP at 12 cm experiences an airway pressure of 1045.5 cm. At 8000 feet that person experiences an atmospheric pressure of 10.92 psi or 767.75 cm. A person using CPAP at 12 at 8000 feet experiences an airway pressure of 779.75 cm. By the time we reach 12,500 feet, we are down to 9.17 psi or 644.71. The small gain from CPAP cannot compensate for the significant drop in atmospheric pressure at altitude and the effect of the greatly diminished partial pressure of oxygen at altitude, but the CPAP does continue to provide a therapeutic pressure stent to keep the airway open. In other words, CPAP cannot possibly compensate for altitude induced SpO2 reduction.

Periodic breathing describes a type of central apnea associated with hyperventilation which reduces the respiratory PCO2 causing hypocapnia and loss of respiratory drive. This is a very real problem for some individuals at altitude, and the resolution is either to remove the individual to a lower altitude or treat the periodic breathing and central apnea with ASV or oxygen therapy to slow the hyperventilation. Other effects of altitude can include very dangerous high-altitude pulmonary edema (HAPE). This is a medical emergency requiring immediate descent and therapy. I think Dr. Ben Blue should speak with some pulmonary physicians familiar with high altitude breathing problems to refine his hypothesis.

[RNeil]

LindenHotAir has much better mail service than I do. I only got the magazine today.

The article is suggesting that pilots might benefit by using CPAP while flying and not sleeping. It says that breathing issues caused by high altitudes is similar to Cheyne-Stokes apneas, which can be helped with CPAP.

If you have a pulse oximeter and a CPAP that can be powered by a battery or the plane's electrical system, it would be interesting to note the oxygen saturation flying at maybe 10,000 feet with and without the CPAP.