ALERT regarding possible re-breathing issues with Resmed Airfit P10
I am a physician and have used probably over 20 different products from full face to nasal mask and pillows. I finally settled for the Resmed Airfit P10 pillows because it's split head strap resulted in much improved position stability over the usual pillow design which tended to pull upward and back. The P10 pulls more directly backward making it much less prone to being dislodged by any lateral pull on the tubing.
I have sent well over 60 of my patients to get sleep studies who were diagnosed with OSA and started using CPAPs. Many used P10s. But a few would say they had a hard time using it because they felt they didn't get enough air or felt claustrophobic. I always reassured they that they certainly got enough air since, if anything the positive pressure would aid in inhalation. But sometime the pressure head on exhalation makes people feel it's harder to breath; but it's breathing out that might feel a little more resisted. The newer machines like the Resmed AirSense 10 solve the expiration problem by the Expiratory Pressure Reduction Option which drops the substantially drops pressure on expiration.
However I do think there is a valid reason why some might feel short of breath (dyspnea) when using the P10. It has a trangular matrix of extremely small exhaust ports that sit on each side of the pillows. They are so small you can not see any light shine through them. It seems the air channels are designed in a way that baffles the air flow. The very positive result is that you can not hear the exiting air and you can barely detect air flow with the back of your hand held in from of the ports.
But I have found a concerning problem with this design. I'm using a AirSense 10 with the AirFit P10. In the colder period of the year I will typically get some water condensation (rein out) in the tubing even when I adjust the temperature and moisture to optimal levels. Usually its not much. I do have the main heated tube encased in an insulated jacket so it's only the terminal tube of the P10 that gets a bit hazed or has a few droplets. However, under these circumstances I believe that the slight moisture is sufficient to significantly block the exhalation ports. I will awaken feeling like something is not right and can detect no air exiting the ports. I have to detach the P10 tube and plug the end. Then while holding the pillows forcefully against my face I have to exhale as hard as I can into the pillows. Usually I will feel a fine spray of water hit my hands and then I can again feel that the air is exiting the ports. Since I believe the ports were substantially or perhaps completely plugged, it would mean that I was re-breathing my expired air. This would certainly cause my CO2 to increase and problably result in lowere O2 eventually since fresh air cannot freely enter the tube. The respiratory center of the brain is sensitive primarily to CO2 rather than O2. So when CO2 increases in your blood (hypercapnia) it leads to feeling a shortness of breath and increased respiratory drive. (This is the same reason why skin diving snorkles are limited in length otherwise you would rebreath your air and get short of breath.) This could be a clinically significant hazaard, especially in someone with marginal cardiovascular or pulmonary function.
This essentially leads to the very condition that our user manuals caution us to avoid doing--taping over the exhaust ports in an attempt to reduce the noise or don't blow on ourselves or our spouse.
Anyway, I am interested to know if anyone else has experienced this problem.
I have tried to write/email Resmed about this but I can find no channel for doing this. They do have a phone contact but it's always a lot easier to have a concern lost in the shuffle when there is no paper trail of the complaint.
Doug
I have sent well over 60 of my patients to get sleep studies who were diagnosed with OSA and started using CPAPs. Many used P10s. But a few would say they had a hard time using it because they felt they didn't get enough air or felt claustrophobic. I always reassured they that they certainly got enough air since, if anything the positive pressure would aid in inhalation. But sometime the pressure head on exhalation makes people feel it's harder to breath; but it's breathing out that might feel a little more resisted. The newer machines like the Resmed AirSense 10 solve the expiration problem by the Expiratory Pressure Reduction Option which drops the substantially drops pressure on expiration.
However I do think there is a valid reason why some might feel short of breath (dyspnea) when using the P10. It has a trangular matrix of extremely small exhaust ports that sit on each side of the pillows. They are so small you can not see any light shine through them. It seems the air channels are designed in a way that baffles the air flow. The very positive result is that you can not hear the exiting air and you can barely detect air flow with the back of your hand held in from of the ports.
But I have found a concerning problem with this design. I'm using a AirSense 10 with the AirFit P10. In the colder period of the year I will typically get some water condensation (rein out) in the tubing even when I adjust the temperature and moisture to optimal levels. Usually its not much. I do have the main heated tube encased in an insulated jacket so it's only the terminal tube of the P10 that gets a bit hazed or has a few droplets. However, under these circumstances I believe that the slight moisture is sufficient to significantly block the exhalation ports. I will awaken feeling like something is not right and can detect no air exiting the ports. I have to detach the P10 tube and plug the end. Then while holding the pillows forcefully against my face I have to exhale as hard as I can into the pillows. Usually I will feel a fine spray of water hit my hands and then I can again feel that the air is exiting the ports. Since I believe the ports were substantially or perhaps completely plugged, it would mean that I was re-breathing my expired air. This would certainly cause my CO2 to increase and problably result in lowere O2 eventually since fresh air cannot freely enter the tube. The respiratory center of the brain is sensitive primarily to CO2 rather than O2. So when CO2 increases in your blood (hypercapnia) it leads to feeling a shortness of breath and increased respiratory drive. (This is the same reason why skin diving snorkles are limited in length otherwise you would rebreath your air and get short of breath.) This could be a clinically significant hazaard, especially in someone with marginal cardiovascular or pulmonary function.
This essentially leads to the very condition that our user manuals caution us to avoid doing--taping over the exhaust ports in an attempt to reduce the noise or don't blow on ourselves or our spouse.
Anyway, I am interested to know if anyone else has experienced this problem.
I have tried to write/email Resmed about this but I can find no channel for doing this. They do have a phone contact but it's always a lot easier to have a concern lost in the shuffle when there is no paper trail of the complaint.
Doug
