A 56-year-old man undergoes a left upper lobectomy. An epidural catheter is inserted for postoperative pain relief. Ninety minutes after the first dose of epidural morphine, the patient complains of itching and becomes increasingly somnolent. Blood gas measurement reveals the following: pH 7.24; PaCO2=58;PaO2=100;HCO3-=28. Initial therapy should include

Thoracic epidural narcotics have become an increasingly popular means of postoperative pain relief in thoracic and upper abdominal surgery. Local action on gamma opiate receptors ensures pain relief and consequent improvement in respiration without vasodilation or paralysis. The less lipid-soluble opiates are effective for long periods. Their slow absorption into the circulation also ensures a low incidence of centrally mediated side effects, such as respiratory depression or generalized itching. When these do occur, the intravenous injection of an opiate antagonist is an effective antidote. The locally mediated analgesia is not affected. One poorly understood side effect, which is apparently unrelated to systemic levels, is a profound reduction in gastric activity. This may be an important consideration after thoracic surgery when an early resumption of oral intake is anticipated.