Inhaled agents: Uterine tone
Last updated: 03/05/2015
All volatile halogenated agents cause dose-related relaxation of the uterus which may lead to increased blood loss during cesarean section. From induction to delivery of the infant 1.0 MAC is given to avoid maternal awareness. After delivery, volatile anesthetics are decreased to 0.5 – 0.75 MAC and oxytocin is given concurrently to decrease the uterine relaxation and thus blood loss. Less than 0.75 MAC interfere with oxytocin’s effects and at elevated doses lead to uterine atony. Nitrous oxide, opioids, and ketamine at less than 2 mg/kg have minimal if any effect.
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