[Severe hypoxemia during cesarean section].

We describe three cases in which severe hypoxemia occurred during cesarean section. The first and second patients showed low oxygen saturation (91, 90%, respectively) on their arrival at the operation room, and hypoxemia deteriorated rapidly after the induction of anesthesia. During surgery low oxygen saturation, ranging from 90 to 95%, persisted until the beginning of spontaneous respiration. In the third patient, oxygen saturation fell suddenly to 93% after the delivery of a neonate, and the arterial blood gas analysis revealed Pao2 68.5 mmHg with 38% oxygen. Hypoxemia was transient and resolved at the end of operation. Parturients have been reported to be likely to develop hypoxemia physiologically. Apnea for a short interval during tracheal intubation may cause severe hypoxemia in parturients compared with normal subjects. Ritodrine, a beta 2 stimulator, which was administered in the first and second patients just prior to operation, may be one of the factors leading to hypoxemia because of its inhibition of hypoxic pulmonary vasoconstriction. Venous air embolism (VAE) may occur frequently during cesarean section, especially during repair of the uterus. VAE may have caused hypoxemia in the third patient. In conclusion, parturients should be monitored carefully with pulse oximetry during cesarean section.