Epidural ketamine for postoperative analgesia

Effect of Intrathecally Administered Ketamine, Morphine, and Their Combination Added to Bupivacaine in Patients Undergoing Major Abdominal Cancer Surgery a Randomized, Double-Blind Study

Objective

Effective postoperative pain control reduces postoperative morbidity. In this study, we investigated the effects of intrathecal morphine, ketamine, and their combination with bupivacaine for postoperative analgesia in major abdominal cancer surgery.

Study Design

Prospective, randomized, double-blind.

Setting

Academic medical center.

Patients and Methods

Ninety ASA I-III patients age 30 to 50 years were divided randomly into three groups: the morphine group (group M) received 10 mg of hyperbaric bupivacaine 0.5% in 2 mL volume and 0.3 mg morphine in 1 mL volume intrathecally. The ketamine group (group K) received 0.1 mg/kg ketamine in 1 mL volume instead of morphine. The morphine + ketamine group (group K + M) received both 0.3 mg morphine and 0.1 mg/kg ketamine in 1 mL volume intrathecally. Postoperative total morphine consumption, first request of analgesia, visual analog score (VAS), and side effects were recorded.

Results

Total PCA morphine was significantly decreased in group M + K compared with groups M and K. Time to first request of analgesia was prolonged in groups M and M + K compared with group K (P < 0.001). VAS in group M + K was reduced from two to 24 hours, and in group M from 12 and 18 hours postoperation compared with group K, with an overall good analgesia in the three groups. Sedation was significantly higher in group M + K compared with group M until six hours postoperation. No other side effects were observed.

Conclusions

Adding intrathecal ketamine 0.1 mg/kg to morphine 0.3 mg in patients who underwent major abdominal cancer surgery reduced the total postoperative morphine consumption in comparison with either drug alone, with an overall good postoperative analgesia in all groups, with no side effects apart from sedation.

Evaluation of the safety and efficacy of epidural ketamine combined with morphine for postoperative analgesia after major upper abdominal surgery

STUDY OBJECTIVE

To evaluate the efficacy of the combination of epidural ketamine and morphine compared with epidural morphine alone for postoperative pain relief following major upper abdominal surgery.

STUDY DESIGN

Prospective, randomized, double-blinded study.

SETTING

Tertiary care referral and teaching hospital.

PATIENTS

46 ASA physical status I and II patients who underwent major upper abdominal procedures.

INTERVENTIONS

Patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 microg/kg whereas patients in Group 2 received epidural ketamine 1 mg/kg combined with 50 microg/kg of morphine postoperatively.

MEASUREMENTS

A blinded observer using a visual analog scale (VAS) for pain assessment followed up patients for 48 hours postoperatively. Top-up dose of epidural morphine was provided when VAS was higher than 4. Analgesic requirements and side effects were compared between the two groups.

RESULTS

Only 40 patients completed the study. There were no differences between the two groups with respect to age, gender, weight, duration, or type of surgical procedure or intraoperative opioid requirements. Onset of analgesia was faster (p < 0.001) in Group 2 (11 min) than in Group 1 patients (25 min). The time for first requirement of analgesia was significantly (p < 0.01) longer (19.8 +/- 9.8 hours) in Group 2 patients than Group 1 (12.8 +/- 6.2 hours). Total number of supplemental doses of epidural morphine required in the first 48 hours postoperatively was also significantly less (p < 0.005) in Group 2 compared to Group 1. Patients in Group 2 had higher sedation scores than Group I patients for the first 2 hours postoperatively. None of the patients in either group developed hallucinations or respiratory depression. Other side effects such as pruritus, nausea, and vomiting were also similar in both groups.

CONCLUSIONS

The addition of epidural ketamine 1 mg/kg to morphine 50 microg/kg improved analgesia after major upper abdominal surgery without increasing side effects.

Effects of intrathecal ketamine added to bupivacaine for spinal anaesthesia

We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p = 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p = 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus, 'strange feelings' and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.