Peroperative titration of morphine improves immediate postoperative analgesia after total hip arthroplasty

Abstract

Purpose: To determine the influence of peroperative titrated morphine on postoperative pain control. Methods: Forty patients received general anesthesia for total hip arthroplasty (THA) and were divided into two groups of 20. In the Peroperative group (Perop group;) morphine was titrated at the end of surgery (3 mg iv every 5 or 10 min) in spontaneously breathing intubated patients, until the respiratory rate (RR) decreased. No morphine was administered to Postop group. In the Post Anesthesia Care Unit (PACU) patients in Perop and Postop groups received morphine until adequate pain relief VAS ≤ 30 mm. Patients used patient-controlled analgesia (PCA) for the next 24 hr. In the PACU, the delay for analgesia, doses of morphine used and incidence of side effects were recorded. Results: In the Perop group, patients received 10.3 ± 1.3 mg (2-20 mg) as peroperative titration and had achieved adequate analgesia more rapidly than in the Postop group (42 ± 7 min vs 76 ± 7 min); P = 0.0026). Analgesia in the PACU in the Postop group required larger doses of morphine (15.4 ± 1.5 mg;) than in the Perop group (7.3 ± 1.3 mg; P = 0.0004). The respiratory rate decrease during peroperative morphine titration was correlated to the morphine dose needed in the PACU (P = 0.035). Respiratory depression in the PACU was more common in the Postop group than in the Perop group (five patients vs no patient P = 0.017). Conclusion: This study demonstrated that the peroperative administration of morphine can facilitate immediate postoperative pain management.