[Influence of anesthetic technique in postoperative analgesia in thoracic surgery]

Abstract

Objective: To compare the intensity of postoperative pain after thoracotomy with 2 anesthetic techniques: 1) thoracic epidural block with bupivacaine administered before surgery (combined anesthesia with isoflurane) and 2) conventional balanced anesthesia with isoflurane and endovenous fentanyl.

Patients and methods: Thirty patients scheduled for thoracotomy by lateral incision (T5-T6) were randomly divided into 2 groups of 15. Group A received 8 ml of 0.5% bupivacaine with adrenalin 1:200.000 30 min before start of surgery while group B received 8 ml saline solution through an epidural catheter inserted to T4-T8. Combined anesthesia (4 ml 0.5% bupivacaine through an epidural catheter 150 min after the first dose and isoflurane in 100% oxygen) was used in group A. Group B received balanced anesthesia with endovenous fentanyl 2.5 micrograms/kg and isoflurane in 100% oxygen. The difference in pain intensity during postoperative recovery was assessed by way of the following variables: number of boluses administered by epidural patient-controlled analgesia (bupivacaine 0.0625% and fentanyl 6 micrograms/ml); score on a visual analog scale of 10 at baseline and at 1, 3, 7, 11, 19 and 43 hours after surgery; and need for additional analgesia (diclofenac) during the 43 hours of study. Arterial gases were measured during the preoperative period and at 1, 3, 7, 19 and 43 hours after surgery.

Results: No significant differences in pain intensity measured on the visual analog scale, by the number of boluses per patients or by need for additional analgesia were found between the 2 groups. The total number of boluses administered and additional analgesic requirements were greater in the group receiving bupivacaine, although the difference was not significant (p = 0.095 and p = 0.056, respectively). Nor were there significant differences in pH and PaCO2 levels for the 2 groups.

Conclusions: Analgesic efficacy after thoracotomy was similar for our 2 groups receiving either combined anesthesia (epidural bupivacaine at 0.5% and isoflurane) or balanced anesthesia with isoflurane and endovenous fentanyl.