We frequently give fluid boluses to patients in the ICU. And a not infrequent question I’ll get from the nurses is, “do you want that on the pump or on a pressure bag?” Does it matter? My usual response is, “whatever,” unless the patient is crashing in which case I opt for the pressure bag. Why? Because they need fluid faster than 999ml/h (which is as fast as the IV pump will go). 999ml/h sounds like a lot until you think about it. That would take an entire hour for a liter bolus to go in. In urgent resuscitation, that’s too long. You can see from this chart that the flow rate of even a 20g IV is a lot more than that.
But, Dr. Eddy Joe Gutierrez makes a pretty solid argument that even if it’s not an urgent situation where we all assume the fluid needs to get in fast, we should be using pressure bags. It has to do with the fact that not all of that fluid ends up in the vascular space. And over time, more and more of it with extravasate out. So, when a liter of crystalloid given over 1 hour, only 200ml will end up staying in the vessel. Hardly enough to raise the SV and thus the MAP. So, maybe we should always be using pressure bags for fluid boluses? His Instagram post below summarizes it nicely, but you should definitely give the entire post a read here.