# CPAP and oxygen depletion



## emt27 (Feb 12, 2014)

Background info: So I work for a private company that has two operations within our branch. One operation has 2 ALS rigs that provide 911 and ALS IFT. Our other operation (the one where I work primarily) is 3-4 BLS units that also do 911 and BLS/ALS transport. For 911 calls we respond alongside the fire department and if it is ALS transport the medic jumps in our rig with their bags. The closest hospital for the BLS operation is 20-30 minutes, and the ALS operation operates in the area directly around the hospital. The closest cath lab is 1-1.5 hours away driving priority. Our company policy is to replace our M sized main oxygen bottles at 900 psi.

An issue that has come up a few times is how quickly we burn through our oxygen during CPAP transports. We had a STEMI 911 call recently where the medic began doing CPAP prior to transport (in the back of our rig). Knowing we would most likely be heading to the cath lab 1.5 hours away, which is our protocol, I went to check our oxygen tank level. Having been previously been on a similar transport with a full 2000/2000 tank and still running out of oxygen  about 5-10 minutes from the cath lab, I knew anything short of a full tank would not work. Our tank was at 1000/2000. Since we were across the street from our base I let the medic know what I was doing and went and grabbed another rig and switched their main with ours, which gave us a 1800/2000 tank. We ended up transporting to the local hospital, but even during that 20 minutes transport our tank was depleted to 800 psi.

So my main question, what would be suggestions on solving this issue? We never know when we might be transporting from the field with a patient on CPAP, and we rarely will have the advantage of being across the street from our base. Are the major issues with CPAP just making sure you have a great seal, in which case perhaps a better mask (perhaps gel based?) might help? Does CPAP just use massive amounts of oxygen and would it be helpful to suggest moving the H tanks, or somehow carrying 2 M sized tanks? 

I've tried to do research, but everything I try and lookup is just flooded with home applications of CPAP for sleep apnea. Thanks in advance!


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## PotatoMedic (Feb 12, 2014)

Figure out a way to quickly connect it to the rigs house O2?  Out of curiosity could you PM me what county your in?


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## rwik123 (Feb 12, 2014)

FireWA1 said:


> Figure out a way to quickly connect it to the rigs house O2?  Out of curiosity could you PM me what county your in?



The M tank IS the onboard rig tank.


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## emt27 (Feb 12, 2014)

Exactly, and it isn't an everyday occurrence where we are transporting a patient on CPAP. Just seems to me that it is a potential issue and i'm just trying to think up ways to mitigate it and/or solve it.

Edit: In my original post I meant to say moving _to_ H tanks, not the H tanks.


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## Aprz (Feb 12, 2014)

It's important to have a good mask seal for the mask to be effective, however, it will not deplete oxygen more quickly if you do not have a great mask seal. I have seen two types of continuous positive pressure (CPAP) equipment, but the most common one is probably the boussignac mask. It's really as simple as using a nasal cannula or non rebreather. You connect the mask to the oxygen tank similar to a nasal cannula (NC) or any other oxygen apparatus, and turn the flow to 15 liters per minute (LPM) for 5 cm H2O, 20 LPM 7.5 cm H2O, or 25 LPM for 10 cm H2O, the cm H2O is the measurement of pressure (similar to mm Hg for blood pressures).

You can use the formula below to determine how long you have until the tank is about empty.

((psi - margin of error) * constant)/LPM

Psi is how much psi is in your tank.

Most people are taught 200 as the margin of error. This is just so you don't wait until the tank is literally empty.

D tank (usually the tank in your airway bag or on your stretcher) constant is 0.16.
M tank (usually the large one in the ambulance) constant is 1.56.

For example, if your tank is 1,600, margin of error is 200, you are using an M tank so your constant is 1.56, and you are using 25 LPM....

((1,600 - 200) * 1.56)/25 = 87 minutes

You'd have about an hour an a half until the tank is about empty.

To me, going for 1,800 to 800 in 20 minutes sounds ridiculous. Instead of subtracting 200 as a margin of error, I am gonna subtract 1,000 (800, which is what remained, plus 200, the margin of error).

((1,800 - 1000) * 1.56)/25 = 49 minutes

Sounds like a leak to me, or something.

There are ambulances that can carry two or more M tanks. Due to long transport times that sometimes require high flow oxygen, I think it can be reasonable to increase the minimum to something 1,500 required at the start of shift.

Also, STEMI doesn't always mean use CPAP. I don't think CPAP is even frequently used for STEMI patients. Primary thing I think CPAP is useful for is to decrease preload via increase intrathoracic pressure for congestive heart failure (CHF) patients to help relieve pulmonary edema. I expect using CPAP for a suspected STEMI patient wouldn't be a common call.


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## VFlutter (Feb 12, 2014)

Aprz said:


> Also, STEMI doesn't always mean use CPAP. I don't think CPAP is even frequently used for STEMI patients. Primary thing I think CPAP is useful for is to decrease preload via increase intrathoracic pressure for congestive heart failure (CHF) patients to help relieve pulmonary edema. I expect using CPAP for a suspected STEMI patient wouldn't be a common call.



In my experience Flash pulmonary edema is fairly common with STEMI patients.


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## emt27 (Feb 12, 2014)

Aprz said:


> Also, STEMI doesn't always mean use CPAP. I don't think CPAP is even frequently used for STEMI patients. Primary thing I think CPAP is useful for is to decrease preload via increase intrathoracic pressure for congestive heart failure (CHF) patients to help relieve pulmonary edema. I expect using CPAP for a suspected STEMI patient wouldn't be a common call.



I'm not saying that the two are necessarily one and the same, but I have been on two STEMI calls where the patient was on CPAP. On the other one we ended up running out of oxygen about 5 minutes away from the hospital. We switched to our portable tank, arrived at the ER and they sent us up to the patients "progressive care unit" room, this while the patient is quickly deteriorating since our portable tank ran out on the way to the room. Patient ended up being rushed down into the ICU and intubated.

 I'm mostly using STEMI's as an example because in our particular system that is a fairly common transport. CPAP is a great tool and seems to work extremely well, but during long transports it burns through our oxygen like nothing. There are other instances of our ALS units having to refuse transports due to the distance (usually to Seattle, which is about 2-2.5 hours away) and the fact we simply can't make it there on CPAP, which then leads to the patient being airlifted.

Our usual method of CPAP through our ventilator, which has a CPAP mode on it. That's the only system i've seen the fire medics that we work with use. Over on our ALS rigs i've seen us use both a ventilator and the disposable type similar to what you were describing. I also remember going on a call where we borrowed a small device from the hospital which pulled a mixture of room air and oxygen and used that for CPAP, though I can't remember what it was called. If I remember correctly it had no battery and had to be plugged into an outlet to work. I'm not sure if that would even be an appropriate application in the case of a STEMI anyways, since i'm guessing it may not provide adequate oxygenation.

I am only an EMT, so this is a bit outside of my scope and I don't have a complete understanding of the physiology behind STEMI's nor the application of CPAP, just saw a potential issue and brainstorming possible solutions.


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## NPO (Feb 12, 2014)

Bring it up to a supervisor or something see if you guys can carry a second tank. Safely of course. This won't work in a van. We work in a urban area, so transport times are not long but we do have a few CCT units with multiple H tanks. Most have 1, some have 2 and one has 4 (2 O2, 2 Medical Air. Its a NICU Unit).


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## DrParasite (Feb 12, 2014)

emt27 said:


> CPAP is a great tool and seems to work extremely well, but during long transports it burns through our oxygen like nothing.


a 90 minute transport time, on CPAP all the time?  That's crazy.

as was previously mentioned, CPAP works awesomely for flash pulmunary edema, but it goes though O2 like it was water.   I used to work in a system that had 20 minute transport times, and knew it then.  I can see worrying about not having enough oxygen for a IFT run, esp if you don't have a second M tank on board.  Unfortunately, there really isn't any way around it.

The only idea I would say is to have a dedicated truck for those long distance transports, which is designed to have 2 M tanks, so when one ends up empty, you can switch to the backup.  Our PICU/NICU truck had 4 as well (2 O2, 1 medical air, and one helox), and it was designed with long distance transports in mind (longest I ever heard was Central NJ to John's Hopkins in Maryland, about 160 miles over 2.5 hours for a double NICU).  And when you leave, make sure all the tanks are completely full before you leave for that run.  Otherwise you run the risk of running out 9/10 of the way through your trip


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## ThadeusJ (Feb 12, 2014)

There's three ways to attack this issue: 1) take more oxygen for your transports; 2) use a device that consumes less oxygen (the Boussignac can consume up to 30 LPM while the Rescuer takes 5-10 LPM and there's everything in between).  Some ventilators consume oxygen just to drive their internal components, 3) if you're using a device that delivers only 100% oxygen, use a blender to add air to the mixture to dilute what you're delivering (while maintaining acceptable SpO2 levels of course).

I have performed transports on vented patients with high FiO2's and PEEP levels from the USA to India and my job was to make sure we didn't run out of oxygen.  To accomplish this mission, I needed to bring 7 "M" size cylinders.  It can be done, but you have to eliminate leaks and minimize consumption.


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## NomadicMedic (Feb 12, 2014)

What type of CPAP are you using? We recently switched to the Pulmodyne disposable CPAP and found our oxygen consumption to be significantly decreased.


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## shfd739 (Feb 12, 2014)

DrParasite said:


> a 90 minute transport time, on CPAP all the time?  That's crazy.




Meh. This happen with us fairly frequently. Monday we went to the border and brought back a pt on bipap. 2.5-3 hr trip. Granted he was on our vent at 50% but it happens depending on where you're working. 

To the OP Id think you need to look at changing devices and making sure shifts are started with a full/nearly full main tank. Typically we change mains at 500psi. CCT trucks change at 1000psi and try to have 2 good spare portables.


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## Tigger (Feb 12, 2014)

We're using the PortO2Vent units, which while often better tolerated by the patient (and inspire near 100% O2), burn through O2 like crazy. 

Our two first out rigs have dual M tanks so generally speaking we do alright. Even at 700 we can usually make a transfer from the Level 4 to the city (fourty minutes). Our second out/supervisor's ambulance only has one, and you have to be careful with those. If a respiratory transfer comes out, we will try and take a dual tank rig, but that's not always possible. We keep three portables in the rigs (two are supposed to be full at all times), but those don't last very long.

If you're going to bring extra portables, make sure they are secured.


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## NomadicMedic (Feb 13, 2014)

We just dropped the portO2vent CPAP for disposables. Still not sure if it was a good idea or not.


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## Tigger (Feb 13, 2014)

DEmedic said:


> We just dropped the portO2vent CPAP for disposables. Still not sure if it was a good idea or not.



Several times we've switched the patient off disposable units carried by other services (why the hospital doesn't then put them on their own BiPAP I'll never know) to ours and the patient has shown marked improvement. I think for that alone they'll probably remain with us for awhile.


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## chaz90 (Feb 13, 2014)

Anecdotally, I've had okay results with our new Pulmodyne disposable units. The first time I used it had a bit of a learning curve getting a good seal on the plastic adapter to house tank portion, but after that it seems to be okay. I will say that I've noticed a huge improvement in O2 consumption on portable tanks. Our default is now 30%, but we carry an FiO2 selector knob with choices of 30/50/70 (not positive on those breakdowns). I haven't had to use the increased FiO2 settings yet and am pretty pleased we're not stuck throwing ridiculous concentrations of O2 at every CPAP patient any more.


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## NomadicMedic (Feb 13, 2014)

I've noticed that the fixed FiO2 doesn't seem to increase pulse ox by any real measure. The PT seems to get symptomatic relief, but I don't see SpO2 getting past 90 in those patients with markedly decreased sats. I've used it only 5 times and haven't had any real issues with the Pulmodyne, but several of the very vocal medics have. So, there is that.


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## Handsome Robb (Feb 13, 2014)

I've noticed that same thing here with the pulmadyne systems as far as them not really increasing the SpO2 but I've only had issues on the really sick patients. We only can do .30 FiO2, no other options.

Since we just got sidestream and I've been off the unit for a couple of months I used to put the ETT adapter for EtCO2 in between the mask and the circuit. Didn't seem very reliable though. Those masks can be a pain sometimes as well, any seal issues with side stream cannulas in place? I never had any glaring issues with regular cannulas on those patients we were talking about above in an attempt to boost the FiO2 some.


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## Tigger (Feb 13, 2014)

Robb said:


> I've noticed that same thing here with the pulmadyne systems as far as them not really increasing the SpO2 but I've only had issues on the really sick patients. We only can do .30 FiO2, no other options.
> 
> Since we just got sidestream and I've been off the unit for a couple of months I used to put the ETT adapter for EtCO2 in between the mask and the circuit. Didn't seem very reliable though. Those masks can be a pain sometimes as well, any seal issues with side stream cannulas in place? I never had any glaring issues with regular cannulas on those patients we were talking about above in an attempt to boost the FiO2 some.



No issues with the et cannulas. Just the hospitals asking "why the hell is there that plastic piece on the cannula?"

When you can learn to put the CPAP mask on right side up perhaps then we can talk about it but till then...


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## TheLocalMedic (Feb 15, 2014)

I like the Pulmodyne, but the plastic bits on the mask seem to break pretty often…


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## chaz90 (Feb 15, 2014)

TheLocalMedic said:


> I like the Pulmodyne, but the plastic bits on the mask seem to break pretty often…



Our models have a Velcro strap option for the cases when our primary plastic bits break off. It's like they saw our CPAP wedging ways coming


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