Table 3.

Morphine loading dose and total morphine consumption (mg) (mean±SD)

	Group 1 (n=13)	Group 2 (n=13)	Group 3 (n=13)	Group 4 (n=13)
Morphine bolus dose	8.25±2.91	5.66±3.04	8.81±2.85	8.70±6.16
Total PCA morphine consumption	101.87±53.31	115.61±43.48	98.37±49.16	61.77±35.38*

^*p<0.05 compared with other groups.

Group 1: control group. Group 2: single-bolus dose of 0.5 mg kg⁻¹ ketamine IV at induction. Group 3: bolus dose of 0.5 mg kg⁻¹ ketamine IV at induction and perioperative ketamine infusion at a rate of 0.25 mg kg⁻¹ h⁻¹. Group 4: a bolus of 0.5 mg kg⁻¹ ketamine IV at induction and perioperative and postoperative ketamine infusion at a rate of 0.25 mg kg⁻¹ h⁻¹