CPAP and BiPAP in asthma

zzyzx

zzyzx

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I understand that the only function for CPAP in asthma is to reduce the work of breathing, and that the current evidence appears to show benefit in its use for severe exacerbations, but doesn't it contribute to air trapping?

If you can use BiPAP (which we don't have pre-hospital), would you use the lowest end expiratory pressure in order to reduce air trapping?
 
Weingart does a great podcast explaining this subject.

Look up the episode labeled coding asthmatic if I remember right.

End result is CPAP is of questionable use, while the inhalation support from Bipap is a definite use
 
I've had very responses when using CPAP in conjunction with Albutarol and Atrovent. Also, saying "only function" does make it sound like it's not that useful, which is not something that I would agree with. BIPAP with a low exp. pressure would be most beneficial, but I don't know any pre-hospital providers in my area that can provide that.
 
My experience is that it works "sometimes". It is worth a try on some COPD/Asthma patients, but don't become over-reliant and ignore the fact that some of these patients will need to be intubated anyway. Increasing their SpO2 via CPAP to 95% means nothing if they are becoming semi-responsive or show now change in work of breathing.

Everyone here has seen a medic who's left their patient on CPAP 'because the sats were coming up', despite the fact that the patient is still in severe respiratory distress and stating no improvement. Don't be that medic.
 
At the moment the only way to provide Bilevel NIPPV (because BiPap is a brand name for a particular device providing a particular mode) is through a mechanical ventilator in non-invasive mode (LTV, Draegar, etc.). It will also consume a lot more oxygen resources that the CPAP devices. Up till a few years ago, the patient outcome studies didn't show a significant difference between CPAP and Bilevel, but you are correct in that any application of positive pressure may exacerbate air trapping. The idea between applying it, however, is that you decrease the pressure differential between the trapped air and the "outside" air while creating a pneumatic stent within the airways, keeping them open and allowing gas exchange to occur.

Similar to air leaving a balloon trying to get past the collapsed passage where you blow in. If you stent that passage, the air in the balloon can rush out faster. At least that's the theory.
 
FiremanMike said:
My experience is that it works "sometimes". It is worth a try on some COPD/Asthma patients, but don't become over-reliant and ignore the fact that some of these patients will need to be intubated anyway. Increasing their SpO2 via CPAP to 95% means nothing if they are becoming semi-responsive or show now change in work of breathing.

Everyone here has seen a medic who's left their patient on CPAP 'because the sats were coming up', despite the fact that the patient is still in severe respiratory distress and stating no improvement. Don't be that medic.
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Sure there are times that NIPPV won't work and these folks will end up intubated. But if their sats are improving than by definition their gas exchange is improving. It might not still be where it needs to be and they might still end up tubed, but if nothing else you've bought some time to hopefully get to the ED and a more controlled environment with more help.
 
What FEV1 indicates the need for intubation in an asthmatic?

What PaC02?
 
If a patient can actually perform a reproducible FEV1, then you have a while to go before they need tubing. Like the original question asks about applying positive pressure on an asthmatic, tubing them and forcing more air in ain't gonna be much better unless you are really really deep in the weeds. I would avoid tubing them at all costs and devote all my energy into reversing the bronchospasm. Follow the PaCO2, but don't tube based on a number. People can survive high CO2 levels, but only for so long. Follow the trend, consider co-morbidities and watch the patient.

But thats just me.
 
Remi said:
Sure there are times that NIPPV won't work and these folks will end up intubated. But if their sats are improving than by definition their gas exchange is improving. It might not still be where it needs to be and they might still end up tubed, but if nothing else you've bought some time to hopefully get to the ED and a more controlled environment with more help.
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Treat the patient and not the monitor.
 
FiremanMike said:
Treat the patient and not the monitor.
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I hope there's a missing *sarcasm* tag here. Agreed that there are certainly times intubation could still be necessary even with improving sats, but Remi's statements are accurate.
 
chaz90 said:
I hope there's a missing *sarcasm* tag here. Agreed that there are certainly times intubation could still be necessary even with improving sats, but Remi's statements are accurate.
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No missing sarcasm, I don't want people to think that increasing sats are "good enough".. As we advance further and further into the integration between technology and medicine, we need to remain vigilant to not look at a number out of context (i.e. SpO2) and use it as the determining factor for patient improvement.

Believe me when I say I mean neither arrogance nor condescension with my post, I am passionate about the improvement of EMS delivery. Sometimes I may come across as crass, it's unintentional.
 
Actually this is a very good point as it applies to CPAP because (as was alluded to) almost every study shows that CPAP prevents intubation 30-50% of the time...meaning it doesn't work to prevent intubation 50-70% of the time. At what point the patient activates EMS, the pathology, co-morbidities and the effectiveness of the device itself are all factors in the success or failure of this therapy. Of course saying "treat the patient not the monitor" is commonplace and logical, I think what it means here is that CPAP therapy is more of an art than a science and numbers are best for trending than making any conclusions about reaching an end point.
 
FiremanMike said:
Treat the patient and not the monitor.
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How about we treat the patient and then monitor? Technology provides us with information that we are unable to have by just looking at the patient....
 
We're now kinda getting to the point where my statement is being taken out of context and my point is being missed..
 
Remi said:
What FEV1 indicates the need for intubation in an asthmatic?

What PaC02?
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Who's measuring either in the field?
 
Brandon O said:
Who's measuring either in the field?
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I can and do monitor paco2 as part of my chem 8+ in the field. Especially with my critical respiratory patients
 
ThadeusJ said:
At the moment the only way to provide Bilevel NIPPV (because BiPap is a brand name for a particular device providing a particular mode) is through a mechanical ventilator in non-invasive mode (LTV, Draegar, etc.). It will also consume a lot more oxygen resources that the CPAP devices.
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Negative Ghostrider, the majority of advanced vents are far more friendly to O2 supplies than CPAP devices, outside high demand patients. And in those patients your CPAP was likely unable to meet the flow.
 
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