[The influence of epidural morphine in the pulmonary function of patients undergoing open cholecystectomy]

Upper abdominal surgeries may cause postoperative respiratory dysfunction. The objective of this study was to evaluate the pulmonary function after laparoscopic and open cholecystectomies, with and without epidural morphine.

In this randomized, double-blind clinical trial, 45 patients undergoing cholecystectomies were divided in three groups: GL, GA, and GAM, composed of 15 patients each. The GL group underwent laparoscopic surgery, while GA and GAM underwent open cholecystectomy, but the former received epidural morphine. Pre- and postoperative spirometry and arterial blood gases were performed. ANOVA was used to verify the hypothesis of equality of the means among the groups. When results were statistically significant, the Tukey test was performed. Paired test t Student was used to verify the hypothesis of equality within a group. A p < 0.05 was considered significant.

The pre and immediately postoperative spirometry results were used to determine: a) forced vital capacity (FVC) in GL versus GA (p = 0.000) and GL versus GAM (p = 0.000); percentage of the reduction of FVC in GA versus GAM (p = 0.001); b) within each group: in GL, FVC (p = 0.020) and forced expiratory volume in 1 second (FEV1) (p = 0.022); in GA, FVC (p < 0.001) and FEV1 (p < 0.001); and in GAM, FVC (p = 0.007) and FEV1 (p = 0.001). The arterial oxygen pressure (PaO2) was reduced in all three groups.

One can conclude that respiratory dysfunction was less severe in patients operated by laparoscopy and that epidural morphine reversed, partially, the postoperative ventilatory disturbances of open cholecystectomy.