Comparing Three Different Doses of Caudal Morphine for Analgesia after Salter Innominate Osteotomy

Background: Single dose caudal block application is preferred among children since it is a safe and easy method. Caudal morphine has an important advantage with its long half-life. However, caudal morphine application has some side effects such as nausea-vomiting, urinary retention, pruritus, sedation and respiratory stiffness and many of those are dose-dependent. The aim of this study was to determine the minimum morphine doses that will provide adequate analgesia and by this way to diminish the life threatening side effects such as respiratory depression as well as comfort-threatening side effects such as nausea-vomiting.

Methods: This double blind, randomized, prospective study, was performed in Gaziantep University among 60 pediatric patients aged between 1-9 years, who were planned to have Salter operation for congenital hip dislocation, with ASA classification of I-II. Premedication was not applied in any of the cases. Patients were sub-grouped randomly and for 15, 20 or 25 μg.kg-1 caudal morphine administration: G15, G20 and G25. Caudal injections were performed under general anesthesia just before the operations. Having total volumes of 0.75 ml.kg-1, caudal injections were performed with 15, 20 or 25 μg.kg-1 morphine together with 0.25% bupivacaine according to the groups. The first time of analgesic requirement was recorded.

Results: The number of cases required analgesia in first 24 hours was determined as 4 (20%), 3 (15%) and 2 (10%) in Group 15, Group 20 and Group 25, respectively. There was not statistically significant difference between groups (P>0.05). In none of the patients, the pain level was as high as causing restlessness (score 2). With single dose Paracetamol, pain cured in all of these patients. Postoperative nausea and vomiting in first 24 hours was reported in 1 (5%), 2 (10%) and 8 (40%) cases in 15, 20 and 25 µg.kg-1 groups, respectively. Although the difference between Groups 15 and 20 was not statistically significant (p=0.548), the number of patients with nausea and vomiting in Group 25 was statistically significantly higher than that of Group 15 and Group 20 (p=0.009 and p=0.025, respectively). In first 24 hours in postoperative period, respiratory depression was not observed in any of the cases.

Conclusions: We determined that decreasing the caudal morphine dose to 15 µg.kg-1 in Salter osteotomy does not decrease analgesia in 24 hours but minimizes nausea-vomiting incidence.