Influence of cigarette smoking on the risk of acid pulmonary aspiration.

Twenty-five non-smokers and 35 smokers who had abstained overnight from cigarette smoking and were undergoing minor elective orthopaedic surgery were studied in order to compare gastric volume and pH. There was no significant difference in aspirated volume and pH both just after intubation and prior to extubation between the two groups, thus indicating that habitual smokers undergoing elective surgery in general anaesthesia do not have increased risk of acid pulmonary aspiration compared with non-smokers.

Failure of epidural analgesia to modify postoperative depression of delayed hypersensitivity.

Delayed hypersensitivity to four common antigens was assessed in 32 patients undergoing major abdominal surgery randomly allocated to either general anesthesia (fentanyl + O2/N2O + postoperative pain relief with systemic opiates) or general anaesthesia + epidural analgesia (local anaesthetics + morphine) continued for 72 h. Skin-test responses were performed 2 days before surgery and 1 day after surgery and compared to a similar retesting schedule in 16 comparable non-operative control patients. Cumulated mean skin-test responses increased from 1290 to 2330 mm2 (P less than 0.0001) during retesting in the non-operative control group. In contrast, mean skin-test responses in patients operated during general anaesthesia + systemic opiates for postoperative pain relief fell from 1422 to 1227 mm2 (P = 0.3) and in patients receiving epidural analgesia from 1228 to 890 mm2 (P = 0.06), without statistically significant differences between these two groups (P greater than 0.5). Thus, surgery leads to depression of delayed hypersensitivity and this impairment in immunofunction is not modified by an epidural analgesic regimen providing adequate pain relief.

A controlled study on the effect of epidural analgesia with local anaesthetics and morphine on morbidity after abdominal surgery.

A hundred patients scheduled for elective abdominal surgery were randomized to either general anaesthesia (low-dose fentanyl) and systemic morphine for postoperative pain or combined general anaesthesia and epidural analgesia with etidocaine 1.5% intraoperatively (T4-S5) and bupivacaine 0.5% 5 ml/4 h for 24 h and morphine 4 mg/12 h for 72 h. Postoperative pain was better controlled by the epidural regimen (P less than 0.0001). We found no significant reduction in postoperative mortality (6% to 2%), pneumonia (28% to 20%), cardiac dysrhythmia (10% to 5%) and wound complications (14% to 11%) by the epidural analgesic regimen. The incidence of deep venous thrombosis (125I-fibrinogen scan) was 32% after general anaesthesia and low-dose heparin and 34% after epidural analgesia with no prophylactic antithrombotic treatment (P greater than 0.9). Postoperative weight loss and decrease in serum-albumin and serum-transferrin, as well as the reduction in haemoglobin and the need for postoperative transfusions, were similar in the two groups. Convalescence, as assessed by postoperative fatigue, restoration of bowel function (flatus, bowel movement and food intake) and the time until the patients were self-aided at their preoperative level, was not reduced by epidural analgesia. Since 50% of the patients in each group suffered from one or more of the above-mentioned postoperative complications, this epidural regimen was not effective in reducing postoperative morbidity after major abdominal surgery despite the achievement of adequate pain relief.

The effect of spinal analgesia and surgery on peroperative drug absorption and gastric emptying in man.

Paracetamol 20 mg kg-1 dissolved in 200 ml of water was given by mouth to seven patients undergoing minor orthopaedic surgery in spinal analgesia, and again 2 weeks later. The rate of paracetamol absorption was significantly delayed by spinal analgesia and surgery, indicating an inhibition of peroperative drug absorption and gastric emptying. The effect of spinal analgesia on gastric emptying was not able to normalize the delayed peroperative gastric emptying produced by surgery, and suggests that surgery is an important factor in peroperatively delayed gastric emptying.