Article Notes
Carbetocin is a long-acting synthetic oxytocin analog. Although a 100 mcg dose is currently recommended, there is still some question as to the ideal dose. Dosing as low as 20 mcg may possibly be equally effective.
Carbetocin is currently only recommended for use during elective cesarean delivery, obviating the need for a post-operative oxytocin infusion currently practiced in many countries. In some countries it is also used after vaginal delivery.
It is at least as efficacious as intravenous oxytocin, and may possibly be superior at reducing postpartum haemorrhage.
Due to it's comparatively high cost compared with oxytocin however, the economic benefit of avoiding post-operative oxytocin infusions has not been demonstrated.
In the scenario of emergency cesarean section after labor augmentation with oxytocin, a much larger dose is likely required and carbetocin cannot be recommended.
One study has suggested a post-operative analgesic benefit of carbetocin vs oxytocin, although the evidence base for this is far from conclusive.
There has been some observational evidence that a greater depth of anesthesia, as measured by BIS, may be associated with an increase in post-operative mortality. In particular the association of the "triple low state" (low BIS, low volatile-ET, low MAP) with post-operative mortality is worrying.
Completion of the Balanced Anaesthesia Study Group’s large RCT looking at this issue however brings us as close to a final word as we may expect. Short et al. (2019) showed no difference in 1-year mortality for older patients undergoing major surgery, whether they received a deep (BIS target 35) or light (BIS target 50) general anaesthetic.
It is likely that earlier observational studies were showing the consequences of intraoperative hypotension resulting from anaesthetic depth, rather than anaesthetic depth itself.
A case report describing the first-reported, successful and safe use of Xenon-based anesthesia in an MH-susceptible 31 year old male.
The authors conclude that this case, along with previous investigation of Xe in susceptible-swine animal models and in vitro human muscle biopsy testing, show that Xenon is likely safe for use in MH-susceptible individuals.
A fascinating historical article, both because of it's current relevance and the glimpse it provides of the exploration of a relatively new drug – along with tidbits regarding the safety of the technique:
"This is borne out by the fact that after many thousands of cases had been done, the first case of convulsions occurred. The intravenous Xylocaine had been increased to a very rapid rate and generalized convulsions ensued. For this case, all that was needed, was to stop the drip, supplement respiration with 100% oxygen and wait several minutes for the convulsion to subside. Thiopental sodium and succinylcholine chloride were at hand but not needed. However, it should be emphasized that this technique is not for the beginner."