CPAP vs BiPAP?

[Angry Birds]

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I always just use BiPAP. From a very practical standpoint, is there any time you use CPAP instead of BiPAP?

Thanks!

(If EMS brings the patient on CPAP, then I just keep them on it unless they want the machine back.)

 

[gro2001]

An argument could be made that CPAP has been shown to be slightly better than BiPAP at improving mortality and staving off intubations in Acute Pulmonary Edema while BiPAP has been shown to be slightly better in COPD. However, the difference does not seem to be huge and I feel that most adults seem to tolerate BiPAP better (and it seems most people, like Angry Birds as well as most of my RTs, autopilot to BiPAP), so I don't make an issue of it and use BiPAP almost exclusively in adults. The only time I use CPAP in adults basically is when I have a person boarding who is admitted for something else and sleeps with a CPAP machine at home.

In infants, CPAP is much better studied than BiPAP, so infants only get put on CPAP if anything. However, this preference seems to have bled over into younger kids too. As far as I can tell without a particular evidence or physiology based reason. I go along with whatever, but end up putting younger kids on CPAP and older kids on BiPAP.

In summary, I think your BiPAP 4 life practice is totally fine in everyone except maybe infants. Maybe.

 

[BAM!]

lots of EMS protocols have prehospital CPAP as a tool. When EMS leaves and take their CPAP with them, just switch over to the ED's BIPAP. You're not going to go wrong with using only BIPAP, like Angry Birds. If there's a bad outcome and you kept them on CPAP, there might be some explaining to do. Besides, another option in a CHF exacerbation --> titrate the EPAP/IPAP ratio until you convert your BIPAP into CPAP.

 

[alpinism]

I'll preface by saying that this is a huge pet peeve of mine.

Overall most EM physicians I've worked with do the same as you and just throw BiPAP on everyone regardless of the situation.

This is obviously the easiest option especially if you've got RTs around to manage these patients.

That being said I think this is bad practice for a couple of reasons:

1. CPAP and BiPAP are not the same thing and are meant for different patients.

I'll let Weingart explain below:

"If your patient has type I respiratory failure [inadequate oxygenation], then they need PEEP. They need CPAP (which is the same thing by a different name). CPAP (PEEP) fixes oxygenation failure. It recruits alveoli. It increases the matching between ventilation and perfusion. And if you have a pulmonary edema patient it decreases pre load and after load. Basically it does very good things for the patient with oxygenation failure. And you’ll see these good things almost immediately. And over the course of the next half hour or so they’ll keep getting better as alveoli pop open. So CPAP or PEEP is for oxygenation failure. Generally we start the setting at five and we can take it up to 15 if we need to. Now if you’re using a standalone machine then they’re going to call it EPAP which is the same thing as CPAP or PEEP. All those terms are synonymous. If the patient doesn’t have a ventilation issue, then they don’t need anything more than expiratory pressure. Just CPAP is all that they need. So don’t bother adding on inspiratory pressure. They don’t need it. If they have purely oxygenation problem then it is just CPAP. The patients with type II respiratory failure [inadequate ventilation], they are the patients who have problems with ventilation; like your asthma patients, and generally your COPD patients as well. What these patients really need is inspiratory pressure support. They don’t really need expiratory pressure. They already have auto peep Because they can’t get air out. So what these patients need is help getting air in. If you take these patients and put them on inspiratory pressure support, then they’ll start exchanging gas again. All of a sudden their oxygen saturation is back to hundred percent if you have them on supplemental FI02. And now the patient is getting their respiratory effort augmented by the machine. They still tell the machine when they need to breathe but the machine helps them get the air in. And they start looking good again. Same thing for your COPD patients. So these type II guys just need inspiratory pressure. And that is going to be IPAP when using a standalone machine and it’s going to be pressure support when using a ventilator. Generally I’ll also start that around five and work my way up to 15. Now most of these machines need just a little bit of Expiratory setting to keep the the masks open. So I’ll put that on 2 or 3 and not beyond that."

2. When you put everyone on BiPAP you're more likely to use the wrong settings.

If you place everyone on BiPAP there's a good chance you're also setting everyone to 10/5 or something along those lines. For the type I pulmonary edema patients this means that they're only getting 5 during expiration which is when they need the pressure the most because their alveoli are collapsing. At the same time for the type II asthma patients this means that they're also getting 5 during expiration which is when they need the pressure the least because they have trouble getting air out of their lungs. What I often notice is that people will just keep turning up both the IPAP and the EPAP when this happens which doesn't fix either probelm. As a result the patients often don't improve or only improve minimally after 30min on the machine and they end up getting intubated anyway.


TL;DR: CPAP and BiPAP are different and you need to know how to set the IPAP and EPAP in patients depending on their specific disease process.

 

[deleted547339]

I only use bipap. You just have to know how to use it.

 

[Petypet]

TL;DR: CPAP and BiPAP are different and you need to know how to set the IPAP and EPAP in patients depending on their specific disease process.

this makes sense physiologically but has it been shown to hold true in the literature? I was told and with limited reading have read that this doesn't pan out when you look at the evidence.

such as in
A comparison of continuous and bi-level positive airway pressure non-invasive ventilation in patients with acute cardiogenic pulmonary oedema: a meta-analysis
or
A comparison of bilevel and continuous positive airway pressure noninvasive ventilation in acute cardiogenic pulmonary edema. - PubMed - NCBI

 

[Jabbed]

this makes sense physiologically but has it been shown to hold true in the literature? I was told and with limited reading have read that this doesn't pan out when you look at the evidence.

such as in
A comparison of continuous and bi-level positive airway pressure non-invasive ventilation in patients with acute cardiogenic pulmonary oedema: a meta-analysis
or
A comparison of bilevel and continuous positive airway pressure noninvasive ventilation in acute cardiogenic pulmonary edema. - PubMed - NCBI

I was also told something similar about "BiPAP vs CPAP increasing mortality in CHF" that didn't quite pan out in the literature. I think that it was a point raised in older studies that has been subsequently investigated and discredited.

Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary edema. - PubMed - NCBI

http://www.atsjournals.org/doi/full/10.1164/ajrccm.165.1.2102075#_i24

"The effects of bilevel positive airway pressure (BiPAP) are less clear since a recent controlled comparison of BiPAP versus CPAP had to be terminated because of increased risk of myocardial infarction in the BiPAP group, despite more rapid improvement in ventilation and vital signs"

 

[deleted547339]

I'll preface by saying that this is a huge pet peeve of mine.

Overall most EM physicians I've worked with do the same as you and just throw BiPAP on everyone regardless of the situation.

This is obviously the easiest option especially if you've got RTs around to manage these patients.

That being said I think this is bad practice for a couple of reasons:

1. CPAP and BiPAP are not the same thing and are meant for different patients.

I'll let Weingart explain below:

"If your patient has type I respiratory failure [inadequate oxygenation], then they need PEEP. They need CPAP (which is the same thing by a different name). CPAP (PEEP) fixes oxygenation failure. It recruits alveoli. It increases the matching between ventilation and perfusion. And if you have a pulmonary edema patient it decreases pre load and after load. Basically it does very good things for the patient with oxygenation failure. And you’ll see these good things almost immediately. And over the course of the next half hour or so they’ll keep getting better as alveoli pop open. So CPAP or PEEP is for oxygenation failure. Generally we start the setting at five and we can take it up to 15 if we need to. Now if you’re using a standalone machine then they’re going to call it EPAP which is the same thing as CPAP or PEEP. All those terms are synonymous. If the patient doesn’t have a ventilation issue, then they don’t need anything more than expiratory pressure. Just CPAP is all that they need. So don’t bother adding on inspiratory pressure. They don’t need it. If they have purely oxygenation problem then it is just CPAP. The patients with type II respiratory failure [inadequate ventilation], they are the patients who have problems with ventilation; like your asthma patients, and generally your COPD patients as well. What these patients really need is inspiratory pressure support. They don’t really need expiratory pressure. They already have auto peep Because they can’t get air out. So what these patients need is help getting air in. If you take these patients and put them on inspiratory pressure support, then they’ll start exchanging gas again. All of a sudden their oxygen saturation is back to hundred percent if you have them on supplemental FI02. And now the patient is getting their respiratory effort augmented by the machine. They still tell the machine when they need to breathe but the machine helps them get the air in. And they start looking good again. Same thing for your COPD patients. So these type II guys just need inspiratory pressure. And that is going to be IPAP when using a standalone machine and it’s going to be pressure support when using a ventilator. Generally I’ll also start that around five and work my way up to 15. Now most of these machines need just a little bit of Expiratory setting to keep the the masks open. So I’ll put that on 2 or 3 and not beyond that."

2. When you put everyone on BiPAP you're more likely to use the wrong settings.

If you place everyone on BiPAP there's a good chance you're also setting everyone to 10/5 or something along those lines. For the type I pulmonary edema patients this means that they're only getting 5 during expiration which is when they need the pressure the most because their alveoli are collapsing. At the same time for the type II asthma patients this means that they're also getting 5 during expiration which is when they need the pressure the least because they have trouble getting air out of their lungs. What I often notice is that people will just keep turning up both the IPAP and the EPAP when this happens which doesn't fix either probelm. As a result the patients often don't improve or only improve minimally after 30min on the machine and they end up getting intubated anyway.


TL;DR: CPAP and BiPAP are different and you need to know how to set the IPAP and EPAP in patients depending on their specific disease process.

I think you're wrong (and weingart) on two things above:

1) Patients with pure hypoxic respiratory failure do benefit from IPAP. Yes, it is the EPAP that helps address the hypoxemia, but (essentially) all patients with pure hypoxic respiratory failure (from an elevated A-a gradient, I.e. The ones you'd be using NIPPV for) will get tired and benefit from a touch of assistance.

2) Give the patients with severe auto-peep all the epap you want, it won't hurt them. Applying an artificial amount of Epap/cpap/peep that is below the intrinsic peep will have no effect on ventilation. In fact, if a patient who is autopeeping and having difficulty initiating the breath, the appropriate thing to do is actually raise the e-peep to approach the I-peep such that the patient becomes more synchronous. Sure, they don't need it on bipap, but you're not hurting them.

 

[Groove]

I think you're wrong (and weingart) on two things above:

1) Patients with pure hypoxic respiratory failure do benefit from IPAP. Yes, it is the EPAP that helps address the hypoxemia, but (essentially) all patients with pure hypoxic respiratory failure (from an elevated A-a gradient, I.e. The ones you'd be using NIPPV for) will get tired and benefit from a touch of assistance.

This.

Most of these pts requiring NIV in the ED (regardless of type 1&2 class failures) are tired and need ventilatory assistance or become tired and need ventilatory assistance. IPAP is useful for all these patients as well as the backup rate in case they suddenly lose their respiratory drive. The IPAP isn't going to hurt them and almost all of them are suffering from some element of respiratory fatigue. As long as you adjust EPAP accordingly based on the underlying pathology, you can essentially BiPAP everyone as long as you understand the settings and gradient. In essence, you can BiPAP both types of patients. Sure, sometimes I leave the pt on CPAP when they come in and EMS has initiated it or if there's an issue with pt-ventilation synchrony, etc.. but most of the time I'm using BiPAP.

Plus, last I checked there was no NVI literature showing the superiority of CPAP over BiPAP that was statistically significant.

 

[WilcoWorld]

It's also worth noting that a lot of these (adult) patients have both COPD and CHF histories, and it's not always clear which disease process is predominating at the moment they hit the door. Starting NIPPV on a tired-appearing dyspneic patient is almost always a good move. If you want to nerd out on the physiology once the CXR, ECG, and BNP are back, AND you've done a bedside echo, have at it - that's part of what makes medicine fun. But please don't withhold NIPPV in your initial resuscitative efforts because you want to figure out if the patient needs alveolar recruitment or inspiratory pressure support before you pick a modality.

 

[RoyBasch]

My preference is to use AVAPS with a wide IPAP range (like 8-30) and then the patient dictates how much inspiratory pressure they need. Seems to work well. I don't ever use CPAP alone; sometimes when using older machines (do not have AVAPS setting available) I manually titrate the settings. I.e. if sating poorly well increase PEEP, if sating well but VBG/ABG shows high pCO2 or patient clinically not pulling good TVs then I will increase the IPAP.

Many patients have polyfactorial respiratory failure; most commonly being a combination of pulmonary edema from CHF, COPD, OHS, and then triggered by an acute infectious process such as PNA. Therefore I prefer to use AVAPS or manually titrate settings rather than letting the underlying process dictate my initial approach. I think I have been pretty successful as I rarely need to rescue intubate a respiratory failure patient who presented still protecting their airway (maybe 1 tube per year in the ER after failing NIPPV).

 

[alpinism]

I think you're wrong (and weingart) on two things above:

1) Patients with pure hypoxic respiratory failure do benefit from IPAP. Yes, it is the EPAP that helps address the hypoxemia, but (essentially) all patients with pure hypoxic respiratory failure (from an elevated A-a gradient, I.e. The ones you'd be using NIPPV for) will get tired and benefit from a touch of assistance.

2) Give the patients with severe auto-peep all the epap you want, it won't hurt them. Applying an artificial amount of Epap/cpap/peep that is below the intrinsic peep will have no effect on ventilation. In fact, if a patient who is autopeeping and having difficulty initiating the breath, the appropriate thing to do is actually raise the e-peep to approach the I-peep such that the patient becomes more synchronous. Sure, they don't need it on bipap, but you're not hurting them.

This.

Most of these pts requiring NIV in the ED (regardless of type 1&2 class failures) are tired and need ventilatory assistance or become tired and need ventilatory assistance. IPAP is useful for all these patients as well as the backup rate in case they suddenly lose their respiratory drive. The IPAP isn't going to hurt them and almost all of them are suffering from some element of respiratory fatigue. As long as you adjust EPAP accordingly based on the underlying pathology, you can essentially BiPAP everyone as long as you understand the settings and gradient. In essence, you can BiPAP both types of patients. Sure, sometimes I leave the pt on CPAP when they come in and EMS has initiated it or if there's an issue with pt-ventilation synchrony, etc.. but most of the time I'm using BiPAP.

Plus, last I checked there was no NVI literature showing the superiority of CPAP over BiPAP that was statistically significant.

Technically speaking both CPAP and BiPAP provide IPAP and EPAP and thus both also provide ventilatory assistance and reduce work of breathing.

The main difference is that in CPAP the (EPAP>IPAP) while in BiPAP the (IPAP>EPAP). So in both cases you're getting increased inspiratory and expiratory pressures its just that in CPAP you're getting more EPAP while in BiPaP you're getting more IPAP. Patients with type I failure mainly need the higher EPAP to keep their alveoli open while patients with type 2 failure mainly need the IPAP to get air into their lungs. This is basically what Weingart was saying only in a more simplified manner.

LITFL has a great section on NIV including a video describing the above concepts on their website:

Non-Invasive Ventilation
Noninvasive Ventilation for the Critically Ill Patient

 

[alpinism]

This.

Most of these pts requiring NIV in the ED (regardless of type 1&2 class failures) are tired and need ventilatory assistance or become tired and need ventilatory assistance. IPAP is useful for all these patients as well as the backup rate in case they suddenly lose their respiratory drive. The IPAP isn't going to hurt them and almost all of them are suffering from some element of respiratory fatigue. As long as you adjust EPAP accordingly based on the underlying pathology, you can essentially BiPAP everyone as long as you understand the settings and gradient. In essence, you can BiPAP both types of patients. Sure, sometimes I leave the pt on CPAP when they come in and EMS has initiated it or if there's an issue with pt-ventilation synchrony, etc.. but most of the time I'm using BiPAP.

Plus, last I checked there was no NVI literature showing the superiority of CPAP over BiPAP that was statistically significant.

The literature is overall not very good but there is a Cochrane Review showing CPAP to be superior to BiPAP in acute cariogenic pulmonary edema.

Non-invasive positive pressure ventilation for cardiogenic pulmonary oedema | Cochrane

 

[deleted547339]

Technically speaking both CPAP and BiPAP provide IPAP and EPAP and thus both also provide ventilatory assistance and reduce work of breathing.

The main difference is that in CPAP the (EPAP>IPAP) while in BiPAP the (IPAP>EPAP). So in both cases you're getting increased inspiratory and expiratory pressures its just that in CPAP you're getting more EPAP while in BiPaP you're getting more IPAP. Patients with type I failure mainly need the higher EPAP to keep their alveoli open while patients with type 2 failure mainly need the IPAP to get air into their lungs. This is basically what Weingart was saying only in a more simplified manner.

LITFL has a great section on NIV including a video describing the above concepts on their website:

Non-Invasive Ventilation
Noninvasive Ventilation for the Critically Ill Patient

That's not correct. In CPAP, IPAP = EPAP. That's what makes it cpap.

I don't know any intensivist that I respect that uses cpap. It's a blunt instrument, whereas bipap allows you to fine tune what you're doing. Does it likely have any real influence on patient outcomes? Probably not, but it's much more physiologic, much more modifyable and much more elegant.

 

[alpinism]

That's not correct. In CPAP, IPAP = EPAP. That's what makes it cpap.

I don't know any intensivist that I respect that uses cpap. It's a blunt instrument, whereas bipap allows you to fine tune what you're doing. Does it likely have any real influence on patient outcomes? Probably not, but it's much more physiologic, much more modifyable and much more elegant.

 

[deleted547339]

If you want to quibble about the 1-2 cm H2O drop during inspiration on cpap, fine. But you're missing the forest for the trees.

 

[Groove]

The literature is overall not very good but there is a Cochrane Review showing CPAP to be superior to BiPAP in acute cariogenic pulmonary edema.

Non-invasive positive pressure ventilation for cardiogenic pulmonary oedema | Cochrane

You're wrong. That's a meta analysis designed to show the benefit of NIPPV compared to standard therapy, not compare BiPAP vs CPAP. The absolute only reason anyone even mentions consideration of CPAP over BiPAP for pulmonary edema in that study is the reduction in mortality when they independently compared it with standard therapy. Yet, when they directly compared CPAP vs BiPAP, they found no substantial difference in mortality.

Yet, I can point you to another meta-analysis from 2006 that showed reduction in mortality in both. The point is, when you really dig into the literature there's absolutely no statistically significant large studies showing the superiority of CPAP over BiPAP regardless of anyones anecdotal experience.

 

[Groove]

Since we're on the topic, I had another CHF'er with COPD combined exacerbation roll into the ER today with a sat at 70% Completely turned this guy around with BiPAP where as I would have tubed him in a heart beat a few years ago. It never ceases to amaze me how many of these guys can be saved from intubation with NIPPV.