[The effect of continuous thoracic peridural anesthesia on the pulmonary function of patients undergoing colon surgery. Results of a randomized study of 116 patients].

Abstract

In a prospective randomized clinical investigation, we examined the influence of continuous thoracic epidural analgesia (TEA) on pulmonary function and pathologic chest X-ray findings. METHODS. One hundred sixteen patients having resection and/or anastomosis of the colon participated in this study; 57 were randomly assigned to the epidural group, whereas 59 were given systemic analgesia. Both groups were comparable with regard to ASA classification and pre-existing disease, as well as operative procedures and surgeons. Bupivacaine 0.75% was given to the TEA patients pre- and intraoperatively (epidural catheter T8/9), and postoperatively they received bupivacaine 0.25% continuously by motor pump for 3 days. We aimed to reach an analgesic spread from T5 to L2. In order to maintain sufficient analgesia, we had to increase the dosage from 19.2 mg/h on the evening of the operative day to 22.2 mg on the 3rd postoperative day. However, under these conditions the number of blocked segments decreased from 9.3 postoperatively to 6.6 on the 3rd postoperative day. Balanced anesthesia (isoflurane plus fentanyl) was given to the control group. Postoperatively, these patients received systemic analgesia on request (piritramide i.m., tramadol, or a simple analgesic). Vital capacity and pain score (10-point nominal analog score) were evaluated at 1, 8, 24, 36, 48, 60 and 72 h postoperatively. Blood gas analyses were taken at 1, 8, 24, 48 and 72 h, and chest X-rays were performed on the 1st, 3rd, and 8th postoperative days. Statistically significant results are indicated by "*" (P less than 0.05) and "*" (P less than 0.005) and "***" (P less than 0.001). The standard deviations were shown in cases of statistical significance. RESULTS. There were significantly lower pain scores by 1.0-2.2 points at 1, 8, 24 and 36 h postoperatively in the TEA group. Fourteen patients in group I required adjustments of the postoperative pain treatment regime: 6 had a unilateral epidural block; in 4 the catheter was withdrawn involuntarily. Up to the 2nd postoperative day, patients in the control group received systemic analgesics significantly more often. The vital capacity (percentage of preoperative value) was significantly higher in the TEA group than in the control group after 1 h (58.5% vs 51.7%) and 8 h (63.9% vs 56.7%). From the 1st postoperative day on there was no difference between both groups with regard to arterial blood gases, there was no difference in pCO2 between both groups 1 h postoperatively; it was, however, significantly lower in patients receiving bupivacaine at 8, 24, 48 and 72 h. There was no difference in pO2 at any time. The number of pathologic chest X-ray findings showed no difference between both groups. Looking especially for infiltrates, dystelectasis, atelectasis, and congestion, we also could not demonstrate any difference between the groups. (ABSTRACT TRUNCATED AT 400 WORDS)