Extradural opioids for postoperative analgesia

ABSTRACT

Effectiveness of extradural injection of morphine [4 mg], pethidine [50 mg], fentanyl [100 mg] and alfentanyl [15 ug/kg] were compared in 80 patients. They were divided into four equal groups, each of 20 patients, for postoperative pain relief. The onset of analgesia was 34.55 +/- 4.86 min. in morphine group, 20.65 +/- 4.13 min. in pethidine group, 10.55 +/- 3.44 min. in fentanyl group and 17.55 +/- 3.7 min. for alfentanyl group. The average duration of analgesia was 10.18 +/- 2.46 h for morphine, 7.04 +/- 2.4 h for pethidine, 5.315 +/- 0.926 h for fentanyl and 3.62 +/- 0.9 h for alfentanyl. The change in cardiovascular parameters [heart rate and blood pressure] were not of clinical importance in spite of being statistically significant, especially with epidural morphine and pethidine. The respiratory parameters showed a significant decrease in respiratory rate in the four groups with insignificant changes in PaO2 and PaCO2, following pethidine, fentanyl and alfentanyl, but in morphine group there was significant elevation in PaCO2. The onset of pain was accompanied by a severe restriction of FVC and FEV1. The earlier and the better restoration of the respiratory function was observed in the fentanyl group. The highest incidence of side effects e.g. itching, nausea and vomiting, occurred with morphine group followed by pethidine and alfentanyl groups and the last with fentanyl group