Analgesic Efficacy of Intravenous Ketamine as a Continuous Infusion vs PCA in the Management of Acute Postoperative Pain in Major Orthopedic Surgery.

"A 10% ketamine solution will be prepared in a 250 cc bag of 0.9% saline (1 mg/cc) using 5 cc from a vial of ketamine that has a concentration of 50 mg/cc. The infusion will be initiated at the time of surgical site closure and will proceed as follows: a bolus of 0.35 cc/kg (equivalent to 0.35 mg/kg) will be administered, followed by a continuous infusion of 0.1 cc/kg/h (equivalent to 0.1 mg/kg/h) for up to 48 hours postoperatively.~Patients in this group will have access to a PCA pump with morphine for analgesic rescue and to monitor daily opioid consumption."

"A mixture of 5% ketamine and 5% morphine will be prepared in a 100 cc bag of 0.9% saline. This will be achieved by using 1 cc of a ketamine vial (50 mg/cc) and 5 cc of a morphine ampule (10 mg/cc). This results in a final concentration of 0.5 mg of ketamine and 0.5 mg of morphine per cc in the 100 cc saline bag.~The pump settings will be configured as follows:~* PCA (Patient-Controlled Analgesia) dose: 2 cc (which delivers 1 mg of ketamine and 1 mg of morphine)~* Lockout interval: 6 minutes~* Maximum dose limit: 15 doses over a 4-hour period~The pump will be available for patient use for up to 48 hours postoperatively."