Influence of bolus size on efficacy of postoperative patient-controlled analgesia with piritramide.

We have examined the influence of bolus size on efficacy, opioid consumption, side effects and patient satisfaction during i.v. patient-controlled analgesia (PCA) in 60 patients (ASA I-II, aged 32-82 yr) after abdominal surgery. Patients were allocated randomly, in a double-blind manner, to receive PCA with a bolus dose of either piritramide 0.75 mg or 1.5 mg (lockout 5 min) for postoperative pain control. Mean 24 h piritramide consumption differed significantly between groups (11.4 (SD 5.8) mg vs 22.5 (18.3) mg; P = 0.001). There were no significant differences in the number of applied bolus doses, pain scores, pain relief (VAS), sedation, nausea, pruritus and patient satisfaction. We conclude that a PCA regimen with a bolus dose of piritramide 0.75 mg and a lockout time of 5 min was effective in the treatment of postoperative pain, but did not reduce the occurrence of side effects.