# Altitude effects on IV



## nihil (Mar 30, 2008)

When you are transporting a patient with an IV and you increase in elevation what happens to the rate of the IV? It seems to me that with less atmospheric pressure at higher elevations the rate of the IV would decrease. As you decrease in elevation the rate would increase. What I heard in class was the exact opposite. They told us the rate increases with elevation gain and decreases with elevation loss. This seems counterintuitive to me. Can anyone clear this one up for me?


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## Jolt (Mar 30, 2008)

[Oops, used poor logic on that post.]


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## Flight-LP (Mar 30, 2008)

nihil said:


> When you are transporting a patient with an IV and you increase in elevation what happens to the rate of the IV? It seems to me that with less atmospheric pressure at higher elevations the rate of the IV would decrease. As you decrease in elevation the rate would increase. What I heard in class was the exact opposite. They told us the rate increases with elevation gain and decreases with elevation loss. This seems counterintuitive to me. Can anyone clear this one up for me?



Boyle's law, simply put, states that at a constant temperature, a volume of gas is inversly proportionate to the pressure applied to it. As applied in a fixed wing air medical environment, devices that utilize air such as an ETT cuff, will increase in volume as altitude increases due to the decrease in air density and atmospheric pressure. However, this does not apply to liquids and even in high altitude operations such as fixed wing, the cabin pressure altitude will be less than 8000ft. So you would not see a big change in your IV rates, nor will Boyle's law apply (unless you experienced an explosive decompression, in which case all of this would be a moot point).

Another factor to consider would be that any reputable air medical service would put their crystalloid and colloid solutions on a pump. 

If you are referring to a ground transport at higher elevation, i.e. the Rockies, the elevation really wouldn't be sufficient enough to show a drastic change. Interesting question though, how did this one come up??????


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## Flight-LP (Mar 30, 2008)

Oh and -5 points for posting an ALS topic in the BLS forum..............jk


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## KEVD18 (Mar 31, 2008)

Flight-LP said:


> Oh and -5 points for posting an ALS topic in the BLS forum..............jk



this is where basics from some place that lets basics start lines will jump up and scream that "we can start lines too"


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## JPINFV (Mar 31, 2008)

2 common misconceptions:

1. That Basic=BLS and Medic= ALS. If it requires a perscription and is anything more than minimally invasive than an OPA/NPA(technically an OPA/NPA is just as invasive as a foley. Both are placing a tube within a tube without breaking the epithelium. The only difference is the length of the tube) than it's ALS.

2. Your patient's needs do not care about arbitrary distinctions between providers and what they call levels. Proper patient care is not about ALS or BLS, but about patients.


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## emtwacker710 (Mar 31, 2008)

yea good point...but this still should have been placed in the ALS forum as most basics cannot do IV's, at least thats how NYS is, im not sure about all the other 49 states


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## BossyCow (Mar 31, 2008)

Even though most basics cannot do IV's, there are many systems where basics assist a medic on these types of procedures.

How does a simple question regarding a process deteriorate into the ALS/BLS wars.. can we stay on topic?


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## gcfd_rez31 (Mar 31, 2008)

who cares if its BLS or ALS question!

just because you are an emt-b doesn't mean your are *never* going to need to know the answer.


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## nihil (Mar 31, 2008)

I posted this in the BLS forum because I am studying to become an EMT-B and part of my training includes monitoring IVs and adjusting the flow rate. We just can't start an IV. 

In class the instructor told us that when transporting a pt. with an IV and you gain in elevation the IV flow rate would increase so you'd have to compensate. When losing elevation the IV flow rate would decrease. This didn't make any sense to me so thats why I'm asking.


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## MSDeltaFlt (Apr 1, 2008)

No it's not.  The amount of elevation changes you would have to encounter might, I repeat MIGHT, be felt if you were transporting a pt from somewhere above normal cloud cover to somewhere below normal cloud cover or vice versa.

What are the odds?  Remote at best.  So I wouldn't worry about it.  Even so, it would be the other way around due to the air in the drip chamber.  Hence why flight crews put pressure bags on IV's.  Not necessarily needed everytime on every flight, but it does come in handy.


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## Jon (Apr 3, 2008)

MS's answer seems to make sense.. but my head hurts.

I thought the question was about the difference 1 foot vs. 3 feet makes regarding the bag being above the patient... but that isn't the question, I don't think.


And I've moved this into the ALS forum, because IV's are USUALLY an ALS skill... but that discussion isn't the topic of this thread.


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## MSDeltaFlt (Apr 3, 2008)

Well if you're talking about the bag over the pt, then you're talking about slope gradients not air in a chamber at all; completely different physics.

Remember skateboarding as a kid?  The steeper the slope, the faster you went.  The lower the slope, the slower you went.  Once you connect that bag to the pt, you have connected the fluid in the bag and the line to the fluid in the pt as a whole.  If you want the fluid to go faster, you need to increase the slope gradient.  You need to put the bag higher to make it go faster.

That's about as simple as I know how to make it.  Hope it helps.


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## Ops Paramedic (Apr 3, 2008)

I don't think i will be able to give you a clear cut answer on this one.  

What you say, makes sense. The higher you go, the less atmospheric pressure there is, which result in less "pressure" on the iv bag/vaculitre.  This will lead one to believe that it should flow slower at altitude (Not refering to flying).

However, i would have to say that you will only notice the difference if you transport the patient from Mount Everest down to the coast line, and while measuring it properly.

Does gravity play a role?  Nope, the acceleration of gravity stays constant, no matter where you are!!


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