Aspects of Postoperative Pain Relief with Special Emphasis on Epidural Analgesia and Major Non-Cardiac Surgery

Abstract: Postoperative pain relief with opioids after major non-cardiac surgery may give rise to adverse effects. The fear of dangerous side effects may therefore limit the optimal use of different treatment modalities in surgical wards. Opioids can be administered alone as an intravenous infusion, or in combination with local anaesthetics as an epidural infusion. Both regimes can be tailored with a patient-controlled option. In the present thesis we evaluated postoperative efficacy and adverse effects of morphine and local anaesthetics administered for postoperative pain relief either as intravenous pain relief (morphine), or as thoracic epidural analgesia (local anaesthetic/morphine) in conjunction with major non-cardiac surgery. 1) It was found that preoperative thoracic epidural analgesia did not add any benefits regarding pain relief or improved pulmonary function compared to thoracic epidural analgesia started after completion of surgery. 2) In patients undergoing thoraco-abdominal surgery, the use of postoperative thoracic epidural analgesia improved dynamic pain perception compared to intravenously administered morphine for five postoperative days. No inter-group differences were found regarding postoperative attenuation of pulmonary function. 3) A new monitoring technique revealed that epidural opioids caused respiratory disturbances, i.e. apnea and bradypnea combined with elevated PaCO2 levels in elderly patients during the first postoperative night. This indicates that elderly patients may need closer postoperative respiratory monitoring. 4) Pump administered pain relief in 2,696 patients in surgical wards for several days demonstrate few serious adverse effects. However, continuous intravenous morphine PCA was associated with a higher incidence of respiratory depression, hallucinations, sedation, and nightmares compared to the use of thoracic epidural analgesia. The latter was also found to mitigate pain more effectively, both at rest and during mobilization, compared to intravenous morphine.