How does pressure support work?

[DarkProtonics]

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I was reading an article about ARDS, and it said to put pts in severe ARDS on 40 cmH2O of PEEP, and 20 cmH2O of pressure support. How does pressure support work? I know it's "above PEEP", and PEEP prevents the alevoli from completely collapsing at the end of expiration, but what does pressure support do?

If a pt had status asthmaticus and needed to be ventilated, would they put him on pressure support ventilation to relieve the auto-PEEP that's preventing him from exhaling?

Why do those portable oxygen tanks COPDers use not have any facility to prove CPAP...there's gas trapping in their alevoli, preventing them from exhaling, so they need CPAP to make their breathing easier, not just oxygen.

I may be wrong on the above, so please correct me.

 

[JayneCobb]

I was reading an article about ARDS, and it said to put pts in severe ARDS on 40 cmH2O of PEEP, and 20 cmH2O of pressure support.

I think you misread the article.

How does pressure support work? I know it's "above PEEP", and PEEP prevents the alevoli from completely collapsing at the end of expiration, but what does pressure support do?

(slight over simplification in process) PEEP is END expiratory pressure, pressure support is pressure when you inhale.

If a pt had status asthmaticus and needed to be ventilated, would they put him on pressure support ventilation to relieve the auto-PEEP that's preventing him from exhaling?

If you have to ventilate a pt, it would be with Volume control or Pressure control initially (with my training bias towards volume control). The treatment for Auto-peep is peep, not PSV.

Why do those portable oxygen tanks COPDers use not have any facility to prove CPAP...there's gas trapping in their alevoli, preventing them from exhaling, so they need CPAP to make their breathing easier, not just oxygen.

Because there are 2 separate issues in COPD, air trapping with poor ventilation leading to increased CO2 retention and then you have hypoxemia. Hypoxemia is due to V/Q mismatching and is easily improved with simple oxygen supplementation. Deliverying Oxygen is easy, CPAP takes a machine to regulate the pressure.

 

[DarkProtonics]

I think you misread the article.



(slight over simplification in process) PEEP is END expiratory pressure, pressure support is pressure when you inhale.



If you have to ventilate a pt, it would be with Volume control or Pressure control initially (with my training bias towards volume control). The treatment for Auto-peep is peep, not PSV.



Because there are 2 separate issues in COPD, air trapping with poor ventilation leading to increased CO2 retention and then you have hypoxemia. Hypoxemia is due to V/Q mismatching and is easily improved with simple oxygen supplementation. Deliverying Oxygen is easy, CPAP takes a machine to regulate the pressure.

Ok, now to the next question: why does pressure support work?

And I re-read the article: it's 10 cmH2O PEEP, 5 cmH2O PS.

Maybe we should advise COPDers to get in their cars, accelerate to 60 mph, and stick their heads out the window to relieve their auto-PEEP 🙂

Is it really that hard to add CPAP to those portable oxygen tanks? All you really need is a high speed fan, correct?

If the pt can't generate the pressure needed to overcome their auto-PEEP, giving them oxygen isn't going to help them much if they can't inhale it. Case in point: When I had an asthma attack in India (thanks to the smog and soot), I couldn't generate the pressure gradient needed to inhale my albuterol (I felt like I was being crucified)...I could've really used CPAP and/or PS then...luckily, it went away on its own.

 

[Depakote]

This is inappropriate use of the physicians forums. Closing.