Table 2. Postoperative opioid use following spinal surgery.

Postoperative PCA data	No ketamine used	Ketamine used	P value
Postoperative PCA use, mean (mg/kg)	0.09 (0.058)	0.12 (0.079)	0.227
Postoperative PCA duration, mean (hours)	12.5 (4.0)	12.8 (3.3)	0.726
Postoperative PCA doses (given/attempted)	0.61 (0.464)	0.59 (0.485)	0.785