Do you replace Mannitol induced volume depletion in Crani's?

[DrOwnage]

Hello everybody,

I've had some conflicting answers on this subject. Lets say you give someone 70g of mannitol and they pee out 2-3L in the next 2 hours. Are you replacing that fluid 1:1 or letting it ride? I'm part of the school of thought that it will lead to volume depletion. The skull is open and its already done its job taking the water with it.

The half life of mannitol is around 2 hours and essentially entirely renally excreted. Giving the losses back wont necessarily lead to brain edema and expansion, correct?

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[Morzh]

I give fluid as they need it, based on some kind of goal-directed measure like clinical signs of hypovolemia. But I don't replace diuresis losses just for the sake of replacing it. Like I don't count the UOP and say "Welp they put out 1500ml of urine but I've only given 1000ml, better give another 500 (despite their art line reading 110/70 without any systolic respiratory variation, and a HR of 60).

Agree though that in a scenario like you mentioned you'll have your initial forced diuresis followed by a likely need for some resuscitation.

 

[ethilo]

I replete losses, the mannitol will keep it out of the brain until it wears off. I won't say it's the right way, I could see your alternative thinking to be reasonable. I'd be cautious if the patient had risk for chf exac but then again is be cautious with giving the mannitol to begin with if that were the case.

 

[zizzer]

I aim for euvolemia. Considering urine loss factors into figuring out the fluid status, but it's only one part of the picture.

 

[deleted875186]

In general I try and keep them dry, aim for euvolemia within reason. Even without mannitol, sometimes the crani patients put out a bunch of urine. I try to replace a good amount of UOP slowly without blousing.

I used to not replace all of it, but I’ve definitely had a few people get hypovolemia and hypotension. This is usually people from the neuro unit who have been getting mannitol for some time and the ICU hasn’t kept up with their losses.

 

[DrOwnage]

Thanks for the answers guys and gals