Reply To: Furosemide cri’s for acute congestive heart failure
Thanks for this good question.
I use furosemide CRI for acute, fulminant HF (when you have a pretty much white out on rads or coalescing B-lines on POCUS exam). I generally use it until the resting RR falls to around 40 breaths per minute and then stop it swapping for boluses thereafter before starting oral meds. I think the majority of papers have shown that it has a superior diuretic effect when compared to intermittent boluses, at least until 8-12 hours of starting the CRI. Ohad et al. (2019) also showed a trend to suggest shorter hospitalisation times with a CRI vs bolus.
I always use a 2mg/kg IV dose first as this will ensure (as much as you can) that furosemide is delivered to the nephron and into the proximal convoluted tubule. The CRI concentration will take longer to reach peak effect. I use a CRI rate of around 1mg/kg/hour, hence why a loading dose in combination with CRI is probably faster at achieving sufficient plasma levels.
Personally, I use the CRI in a syringe driver that is pretty accurate so I don’t tend to dilute with fluids. Adin et al (2003) showed that you can dilute without precipitation to 10mg/ml with lactated Ringer’s, normal saline, sterile water or D5W and to 5mg/ml with sterile water or D5W for a max of 8 hours without precipitation.
You do tend to see hypokalaemia when using either boluses or a CRI. I don’t supplement with potassium routinely as it is probably best to keep an eye on electrolyte balance. If the animal is eating then potassium will be relatively maintained in dogs, but can be more of a problem in cats. I would usually check renal params and electrolytes prior to starting diuresis and if all is normal then check them again 24 hours later and daily until they go home. If not normal or they fall over that time period I will supplement with oral potassium and only use fluid supplementation if I feel that they are symptomatic for hypokalaemia (which tends to only be an issue in our feline friends).
Hope that helps.