(06-20-2013 01:13 PM)Sach_nyc Wrote: I would like to know which kind of machine (cpap auto, bipap auto, auto sv etc) will immediately increase the pressure if airway is fully obstructed and patient has stopped breathing. I have seen that cpap and bipap takes many minutes to increase the pressure and they will simply will not increase the pressure if patient airway is totally collapsed and has stopped breathing altogether. I have heard AutoSV machine can do that as they control pressure breath by breath. Is that so? Does anybody has experience with such machines?
A simple test for that machine will be to obstruct the flow by hand and see pressure increases to maximum level permitted. Also, please include brand and model of machine which you recommend.
(06-21-2013 12:13 PM)Sach_nyc Wrote: In my cpap machine, sometimes pressure does not increase immediately and i cannot sleep as I feel obstructed. This happens when I am very tired or not feeling well.
So, obviously I think a machine which immediately increases pressure to open obstruction is better. Auto SV seems like does this but yes, good idea to talk to doctor.
To answer your original question, only an ASV machine such as ResMed S9 VPAP Adapt (new model 36037 is more capable than previous model 36007) or Philips Respironics System One BiPAP autoSV Advanced (now Model DS960TS includes humidifier with Heated Tube) will immediately increase the pressure if patient has stopped breathing (for whatever reason, whether or not the airway is obstructed).
Keep in mind that the phrase "will immediately increase the pressure" really means this: the pressure will alternate higher and lower, to cause inhalation and exhalation, so there will be no interruption of the patient's usual breathing rate.
The amount of pressure increase (the amount that the inhale pressure is higher than the exhale pressure) is called the amount of Pressure Support.
On my machine, if I consciously will myself to relax and not breathe but I keep my throat open, the machine will keep me ventilated, will keep air entering and exiting my lungs (as long as the machines's pressure settings allow the machine to increase the Pressure Support to 10 or higher, which will be high enough for the machine to do for me all the work of breathing).
Pressure support is the name used for the difference between the inhale pressure versus the exhale pressure. ASV machines automatically adjust the Pressure Support to keep us ventilated. For example, if recently I had been taking an average of 15 breaths per minute and my breathing suddenly pauses, the machine will work to keep me taking 15 breaths per minute by increasing the pressure for a second or two to cause inhalation, and then will lower the pressure for a few seconds to cause exhalation, and it will repeat the cycle to produce 15 breaths per minute (or at whatever bpm rate I had been recently breathing).
On my machine, if I close my throat (for example, to swallow some saliva) this will completely block the airway for a couple seconds, and the pressure will immediately (within a second or less) increase the pressure to try to get me to breathe (up to its maximum setting or until I finish swallowing and start to breathe again).
Does not matter whether the throat is closed (obstructive event) or open (central event), the machine immediately responds.
Here is a link to the Philips Respironics System One Comparison Guide: