Patient-controlled oral analgesia versus nurse-controlled parenteral analgesia after caesarean section: a randomised controlled trial

We assessed the effectiveness of early patient-controlled oral analgesia compared with parenteral analgesia in a randomised controlled non-inferiority trial of women undergoing elective caesarean section under regional anaesthesia. Seventy-seven women received multimodal paracetamol, ketoprofen and morphine analgesia. The woman having patient-controlled oral analgesia were administered four pillboxes on the postnatal ward containing tablets and instructions for self-medication, the first at 7 h after the spinal injection and then three more at 12-hourly intervals. Pain at rest and on movement was evaluated using an 11-point verbal rating scale at 2 h and then at 6-hourly intervals for 48 h. The pre-defined non-inferiority limit for the difference in mean pain scores (patient-controlled oral analgesia minus parenteral) was one. The one-sided 95% CI of the difference in mean pain scores was significantly lower than one at all time-points at rest and on movement, demonstrating non-inferiority of patient-controlled oral analgesia. More women used morphine in the patient-controlled oral analgesia group (22 (58%)) than in the parenteral group (9 (23%); p = 0.002). The median (IQR [range]) number of morphine doses in the patient-controlled oral analgesia group was 2 (1-3 [1-7]) compared with 1 (1-1 [1-2]); p = 0.006) in the parenteral group. Minor drug errors or omissions were identified in five (13%) women receiving patient-controlled oral analgesia. Pruritus was more frequent in the patient-controlled oral analgesia group (14 (37%) vs 6 (15%) respectively; p = 0.03), but no differences were noted for other adverse events and maternal satisfaction. After elective caesarean section, early patient-controlled oral analgesia is non-inferior to standard parenteral analgesia for pain management, and can be one of the steps of an enhanced recovery process.