RE: First Night with CPAP.. some questions
CPAP history.In the beginning there was no CPAP because there was no Sleep Apnea. At least it wasn't recognized, by anyone.
The Dr. Sullivan came along. He knew that sleep apnea existed and there was no treatment for it. I mean how could you keep the airway from collapsing? He was toying with a radical Idea of using air pressure to splint the airway open. His solution, modify a vacuum machine to blow rather than suck. He removed the motor and blower, added a few controls to manage the pressure and voilà, he had the world's first kluged together CPAP machine. Patient one had severe apnea. He was selected because he was severe. Once he started he found it made a huge difference, and he wouldn't let them take him off the machine, and he eventually took it home.
The basic CPAP machine, even today, delivers a single constant pressure which splints open the airway. No flex, no EPR, no easy breathe, nothing to make it easier for the patient to breathe, and certainly no auto mode to self adjust. Just a single fixed pressure. Every CPAP manufactured today can perform this simple basic function, ResMed and Phillips Respironics are completely equal at this level.
Now let's advance to a BiLevel machine.
A basic BiLevel (S or Spontaneous mode), delivers 2 fixed pressures, one for inhale and a lower one for exhale. The Exhale pressure or EPAP performs the same function as Pressure on a CPAP.,. The inhale pressure or IPAP is used to treat hypopneas, flow limits, RERAs, UARS, and even snores. Basic CPAPs use a higher pressure to manage these. On BiLevels the difference between EPAP and IPAP is called Pressure Support (PS). Inhale pressing always higher than exhale pressure And the difference is called PS. That is all PS is. At this level all BiLevels are the same. ResMed, Phillips Respironics, and others are the same.
The manufacture's realized that BiLevel therapy was more comfortable than straight CPAP pressure. Going to BiLevel is a path for 'non-compliant CPAP users. So they added a 'Comfort' feature to lower the applied pressure on exhale. How they did this makes a big huge difference. Logically and in the literature Flex, (Respironics) and EPR (ResMed) should provide very similar response, but they don't. IMHO ResMed wins this battle. ResMed's EPR, when pressures are adjusted as they would be on a BiLevel, even on CPAP, behaves identically to PS within its limits of being only 1,2,3 cmw. As such ResMed CPAP using EPR matches BiLevel treatment of Hypopnea, RERAs, Flow Limits, and UARS. Flex does not. Flex lowers pressure on exhale proportional to how hard you breathe typically 1-2 cmw. It does this with minimal if any impact on Hypopnea, flow limits, RERAs, UARS, snores. Again, winner ResMed.
Auto algorithms. Winner ResMed, here's why.
Phillips targets snores, after a few it slowly increases pressure. To decrease obstructive events a PR machine requires a higher min pressure to get ahead of events. A ResMed responds to Flow Limits, the lowest of obstructive events and does so by aggressively raising the pressure and thus eliminating obstructive events.
Flow Limits are an indicator of airway resistance. Everyone has some. They are one of the things we look at in zoomed view of the flow rate chart. They represent a restriction in the airway. And they are the fundamental part of UARS, Upper Airway RESISTANCE Syndrome. RERAs which are a series of flow limits ending with arousal.
I hope this helps you understand some.
