[Continuous peridural anesthesia in abdominal surgery. An alternative for elderly patients]

Being advanced in years is not in itself a high risk in anaesthesia; however, altered pharmacokinetics and pharmacodynamics, mental dysfunction and the administration of anaesthetics complicate the postoperative period. In order to examine the problem of sedation in elderly patients, we studied the effects and side effects of continuous peridural anaesthesia for abdominal surgery. METHODS. On the day before surgery we inserted a peridural catheter (Perifix 400, Braun, Melsungen, FRG) between T-12 and L-4 in 52 patients in a sitting position (mean age 69.3 +/- 10.9 years) using the loss-of-resistance technique. If no signs of spinal anaesthesia became apparent, the exact position of the catheter was determined using 9 or 10 ml bupivacaine 0.5%. Next day, after premedication with atropine, pethidine or midazolam, 20-25 ml bupivacaine 0.5% was instilled through the peridural catheter. During surgery patients were sedated using a small dose of propofol. We also insufflated oxygen (2 l/min). Blood pressure, heart rate, and blood gases were monitored and electrocardiography and pulse oximetry performed. As postoperative pain therapy, we administered morphine through the peridural catheter at intervals of 8 h. For statistical evaluation we used Wilcoxon's test. RESULTS. An adequate degree of analgesia was found between T-4 and T-7 and abdominal muscle relaxation was satisfactory. Heart rate decreased by 10.3% after the administration of local anaesthetics. After surgery had begun, blood pressure decreased over a period of 30 min (systolic by 20.5% and diastolic by 14.2%) but it remained constant at this level during the rest of the operation (see Fig. 1). Neither of these side effects was significant. Oxygen saturation and blood gases were normal. During the operation, a mean dose of 325 mg propofol/h was necessary to maintain sedation. After surgery all patients were awake, suffered no pain and had complete amnesia with regard to the operation. The postoperative peridural dosage of 5 mg morphine (three times in 24 h) was very effective. Because some patients vomited we used between 50 and 100 mg tramadol (four times in 24 h) instead of morphine. Early mobilization of patients was possible and there were no pulmonary complications such as pneumonia. CONCLUSIONS. If carried out by an experienced physician, continuous peridural anaesthesia can be an alternative method in abdominal surgery for elderly patients. We see advantages in the minimal disturbance of pulmonary and mental function, in the minimal amount of sedation required and in the successful postoperative pain therapy.