Anesthesia and gastrointestinal surgery.

Anesthesia can have various effects on the outcome of surgery, especially gastrointestinal procedures. Many anesthetic agents, for example, produce a fall in lower esophageal sphincter pressure, which can allow reflux of gastric contents into the lower esophagus. This can lead to potentially fatal aspiration of vomit. Anesthesia also alters gastrointestinal motility, secretion, and absorption; postoperative opiate analgesia in particular contributes to delayed gastric emptying. Anesthetic technique can affect the success of intestinal anastomosis; for example, intravenous induction agents and some inhalational anesthetics decrease regional blood flow, whereas regional anesthetics may act to increase colonic blood flow. Other aspects of anesthetic management are also discussed as they relate to surgical outcome; examples are the use of invasive monitoring in elderly patients, the importance of oxygen delivery to the anastomosis, and the effect of transfusion on survival after surgery for carcinoma.