Oxytocin Study Raises Concerns About Carbetocin Use
This study supports the clinical experience of many obstetric anesthesiologists in the use of oxytocin and warrants incorporation into clinical practice. Would the authors agree that further studies are required in this area, including the hemodynamic effects of different dosing regimes in different clinical circumstances?
There is also relevance for those obstetric anesthesiologists who persist in using carbetocin off-label as a uterotonic for caesareans after failed vaginal delivery. As Foley et al1 correctly point out, the ED90 of oxytocin is significantly increased after labor augmentation with oxytocin.2 Similarly, the ED90 of carbetocin is increased to 140 µg after failed vaginal delivery,3 a dose associated with significant cardiovascular side effects and significantly more than the 100 µg used in a standard dose. The longer half-life of carbetocin compared to oxytocin prevents additional doses or additional use of oxytocin. The effects on postcesarean bleeding have not been adequately investigated, and, for this reason, the off-label use of carbetocin must be actively discouraged outside of appropriately designed clinical investigations.