Article Notes
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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.