What is the function of pressure support and why limit the maximum cpap pressure??

[GreenBean]

I see therapy settings choice for minimum and maximum pressure support. Mine was originally set for 4-6. What is it the effect of the lower setting and the higher setting? When do they come into play? What does widening the PS range do? While I'm at it - I frequently see suggestions to reduce the higher pressure limit (often initially set to 20 as mine is) because the charts show that the actual pressures don't exceed a certain, lower, number. Why not just leave it high, and available?

Thanks for any explanations. I keep trying to figure out how all (any) of this works by reading most of the threads whether they seem to apply to me or not, but I still feel lost.

[Wulfman...]

I see therapy settings choice for minimum and maximum pressure support. Mine was originally set for 4-6. What is it the effect of the lower setting and the higher setting? When do they come into play? What does widening the PS range do? While I'm at it - I frequently see suggestions to reduce the higher pressure limit (often initially set to 20 as mine is) because the charts show that the actual pressures don't exceed a certain, lower, number. Why not just leave it high, and available?

Thanks for any explanations. I keep trying to figure out how all (any) of this works by reading most of the threads whether they seem to apply to me or not, but I still feel lost.

search.php?keywords=%22pressure+support%22

From the manuals:

Pressure Support is the difference between delivered IPAP and EPAP.

Pressure Support = IPAP - EPAP


PS Min

This screen allows you to modify the Minimum Pressure Support setting. This setting is the minimum difference that is permitted between IPAP and EPAP while Auto Bi-level therapy mode is active. You may adjust the setting from 0 cm H2O to the Maximum Pressure Support setting. This screen only displays if Auto Bi-level mode is enabled.

PS Max

This screen allows you to modify the Maximum Pressure Support setting. This setting is the maximum difference that is permitted between IPAP and EPAP while Auto Bi-level therapy mode is active. You may adjust the setting from 0 cm H2O to the minimum value of either 8 cm H2O, or the difference between Max IPAP and Min EPAP. This screen only displays if Auto Bi-level mode is enabled.



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[palerider]

I see therapy settings choice for minimum and maximum pressure support. Mine was originally set for 4-6. What is it the effect of the lower setting and the higher setting?

Respironics thinks that a varying PS could be beneficial.. those settings allow that... Resmed doesn't think it's valuable... I don't know either way.

When do they come into play?

See above.

What does widening the PS range do?

allows for a greater variation in the PS.

While I'm at it - I frequently see suggestions to reduce the higher pressure limit (often initially set to 20 as mine is) because the charts show that the actual pressures don't exceed a certain, lower, number. Why not just leave it high, and available?

Some people don't understand that for most people, under most conditions, the max pressure is totally irrelevant. If your pressure only gets to 10, it doesn't matter if max is 11, 15, 20, or 25....

[GreenBean]

Thank you - the max cpap pressure explanation makes sense. It is essentially irrelevant unless you are topping out at the set pressure. So if my pressure doesn't go above 14, it doesn't matter if the setting is for 20, but it should be at least a few notches above 14.

My original settings were ipap 20, epap 5, pressure support 4-6. For my initial four months, before paraesophageal hernia surgery my AHI was almost always 1.0 +/- a little. After surgery I couldn't tolerate the same setup for more than a few hours. I'd feel like I was suffocating and would rip off the mask. I'd occasionaly try again, but was very frustrated. DME was useless (which I now know is common). Found this forum and have been trying to get it right again. Snoring and OAs were awful. Advice from here to raise epap was great help. I am doing much better.

I still do not understand pressure support, though. I can set the PS to 4.5-7 which I am currently using, but my epap is 7 and my ipap is 20. That is a pressure spread of 13. I somewhat randomly chose the 4.5-7 PS just to see what difference if any it would make. It doesn't seem to make any difference. That's why I am trying to figure out what it does as far as effect.

[palerider]

Thank you - the max cpap pressure explanation makes sense. It is essentially irrelevant unless you are topping out at the set pressure. So if my pressure doesn't go above 14, it doesn't matter if the setting is for 20, but it should be at least a few notches above 14.

Yup... The only valid reason to set a lower max pressure is if you're getting aerophagia, or other issues.

I still do not understand pressure support, though. I can set the PS to 4.5-7 which I am currently using, but my epap is 7 and my ipap is 20. That is a pressure spread of 13. I somewhat randomly chose the 4.5-7 PS just to see what difference if any it would make. It doesn't seem to make any difference. That's why I am trying to figure out what it does as far as effect.

So, your epap isn't 7 and ipap isn't 20... if it were, your PS would be 13, and you'd be dizzy from hyperventilating.

your MINepap is 7, and MAXipap is 20, so when you start out, your actual epap is 7 and ipap is 11.5 (epap + min PS) then it will vary as the night goes on.

[GreenBean]

Thank you, palerider. With that explanation, I can now go to sleep. I don't know that it makes any difference to me as far as any effect on my therapy, but it was bothering me that I didn't understand what the heck the numbers meant.

[Holden4th]

The plus of BiPAP (for me anyway) is that with pressure support I can lower my exhalation pressure further than EPR would allow. From a comfort level this works well for me. Resmed and Respironics use PS in different ways. Respironics has a variable PS system with a min and max level. Resmed has a fixed system. I'm not sure if one is superior to the other but all I can say is that I went from Respironics to Resmed and am very happy with the change.