The effect of fentanyl administered epidurally by patient‐controlled analgesia, continuous infusion, or a combined technique of oxyhaemoglobin saturation after abdominal surgery

The aims of this study were to determine the effect of three different modes of epidural administration of fentanyl on oxyhaemoglobin saturation and pain control. Forty-three patients undergoing elective abdominal surgery were randomly allocated to the following groups: (1) continuous infusion of fentanyl at a rate of 50 micrograms.h-1 with additional epidural boluses (25 micrograms) as required; (2) patient-controlled analgesia using a 25 microgram epidural bolus of fentanyl with a 15 min lock-out period; (3) a combination of patient-controlled analgesia and continuous infusion. Oxyhaemoglobin saturation was measured by continuous computerised pulse oximetry for 48 h after operation together with pain and sedation scores. In the first 24 h after surgery patients in the continuous infusion group spent a significantly greater proportion of time below oxygen saturations of 94% and 85% than those in the other two groups. On day 2 all oxygen saturation measurements were worse than during day 1, but differences between groups were not significant. Those patients receiving patient-controlled analgesia required significantly less fentanyl than patients in either of the other groups (p < 0.05). However, the mean pain and sedation scores did not differ significantly between the three treatment groups. There was no association between total fentanyl dose and oxygen saturation values. Overall, self-administered fentanyl appeared to cause less oxyhaemoglobin desaturation than nurse-administered analgesia without any loss of analgesic effect.