Lower esophageal contractility predicts movement during skin incision in patients anesthetized with halothane, but not with nitrous oxide and alfentanil.

The frequency of spontaneous lower esophageal contractions (SLEC) has been proposed as one measure of anesthetic depth. The authors tested the hypothesis that SLEC frequency can predict movement in response to skin incision during halothane or nitrous oxide/alfentanil anesthesia. The incidence of movement during skin incision was compared with the frequency of spontaneous lower esophageal contractions in 20 healthy patients anesthetized with halothane. Esophageal contractility was determined using the Lectron 302, which senses the pressure in a water-filled balloon positioned in the distal esophagus. Absence of SLEC in the 6 min preceding incision correlated with no movement, with one exception (n = 9). All but one patient having greater than or equal to 2 SLEC in the 6 min preceding skin incision moved (n = 8) (P less than 0.01). Sixteen additional patients anesthetized with nitrous oxide (70%) and alfentanil demonstrated no correlation between SLEC frequency and movement. These data suggest that the frequency of spontaneous lower esophageal contractions, and its ability to predict movement, depends on anesthetic type.