We’ve previously mentioned total ketamine anaesthesia in our post on war surgery, using a simple i.v. drip. Today, I talked to a friend and colleague of mine with extensive experience from MSF (Médecins sans frontières – Doctors without borders). Here’s his handy tips on ketamine infusion anaesthesia in the developing world.
Ketamine i.v. drip infusion
Mix 500mg of Ketamine in a bag of 500 mL saline, to get ketamine 1 mg/ml. Get the patient’s weight in kilograms. Let the starting point for your maintanence dose of ketamine i.v. drip infusion be [the patient's weight i kg] drops per minute. This will equal around 4 mg/kg/hr. Adjust to effect.
Ketamine induction cocktail
You will still need an induction dose of ketamine 1-2 mg/kg i.v. For children (or grown-ups) where you can’t easily get i.v. access while they’re awake, you can use a dose of ketamine 5-8 mg/kg i.m. for induction. You can also mix in atropin and a little midazolam in the same i.m. syringe to give them the full cocktail i.m. induction.
Remember, while ketamine is probably the most stable among any of the quick acting induction agents we have, ketamine still needs to be dose adjusted for bled-out, unstable patients. And, obviously, tips like these are not medical advice, but a tip to be used at your own discretion and with your own clinical judgement. Anyway, thanks for the tips, Jonas!
Thomas, I love you! This is great. An American paramedic was asking me about how to do ketamine sedation in the helicopter without an infusion pump and I wrote back about my time in Africa, using ketamine drips like what your friend here has mentioned.
I did not describe it so nicely like you have here so have sent him a link to your article. keep up the great blogging, Sir Viking!
can you check that dosing rate with your friend, Thomas.
4mg/kg/min seems a bit high
Glad you liked it, Minh! I really enjoyed Jonas’ tips as well. Handy bush tips!
Sorry about the dosing rate. I didn’t check back with him, as this was a simple case of me thinking one thing and writing another. It’s mg/kg/hr not mg/kg/min. My bad.
Thanks for pointing that out – and with an almost British sense of understatement! I set it straight in the post as well. I’m glad someone’s vigilant around here.
About the rate, I found this paper listing ketamine 2 mg/kg/hr, whereas anaesthetists at my hospital advocate 5-6 mg/kg/hr. So 4 mg/kg/hr sounds like a decent starting rate for your maintanence dose. Season to taste.
Apologize for the late reply:
Considering pharmacodynamics with main effect wearing off in 15-20 mins,
and with induction of 1mg/kg faster than slower I’d
go with the 4 mg/kg/hr dosis and adjust it.
2mg/kg/hr really seems to small a dose.
3-4 to start and 5-6 if necessary…
Pingback: DRIP DROP | ScanCrit.com
Pingback: Ketamine for primary care providers in remote medicine | PHARM