Remifentanil (Ultiva) is a potent (~200-300 times more than morphine), short acting, titratable narcotic infusion I use for moderate/deep sedation and maintaining general anesthetics. Unlike many drugs which rely on hepatic and/or renal metabolism, remifentanil’s metabolism is through nonspecific plasma esterases. This explains why the drug does not “build up” compared to other infusions. Consequently, remifentanil’s context-sensitive half time remains independent of the duration of the infusion. In other words, it doesn’t matter if you run the infusion for an hour or twelve hours, the drug’s half time is reliably less than 10 minutes.
As a powerful narcotic, it also confers a degree of synergy with hypnotics like propofol allowing me to use a lower dose of the latter to promote hemodynamic stability and faster/cleaner emergences. Remifentanil also has a fair amount of data suggesting acute opioid tolerance and paradoxical hyperalgesia (increased sensitization to noxious stimuli) from its usage. Whenever I use it in the perioperative setting, I’m mindful that its analgesic effects will quickly subside and affect post-operative pain management for the aforementioned reasons. In anticipation, I incorporate multimodal techniques whenever possible by administering longer acting narcotics, local infiltration, regional techniques, ketamine, NSAIDs, gabapentinoids, etc.
As always, drop me a comment with any questions! 🙂
How do you usually dose your Remi infusions (and how much do you increase) and boluses?
I intentionally don’t discuss doses on my pharmacology posts because every situation is different based on patient factors, ICU/operative factors, etc. That being said, 0.05 mcg/kg/min is an average dose I’ll start at.