Table 1.

Baseline characteristics and intraoperative data from each group before and after propensity score-matching

	Before matching			After matching
	Ketamine (+) n=129	Ketamine (–) n=121	P- value	Ketamine (+) n=89	Ketamine (–) n=89	P- value
Age; years	65 [55–72]	67 [55–72]	0.84	65 [55–72]	64 [54–73]	0.91
Sex; Male/female	78/51	77/44	0.70	57/32	50/39	0.36
BMI; kg/m2	22.0 ± 4.3	21.2 ± 3.4	0.12	21.5 ± 3.9	21.5 ± 3.5	1.00
Operation time; min	674 ± 118	648 ± 115	0.09	662 ± 119	652 ± 120	0.56
Anesthesia time; min	775 ± 120	742 ± 120	0.03*	759 ± 118	748 ± 127	0.53
In-Out balance; mL	3002 [2250–3776]	2733 [2192–3800]	0.45	2955 [2067–3748]	2878 [2114–3800]	0.95
Blood transfusion	73 (57%)	81 (67%)	0.12	53 (60%)	55 (62%)	0.88
TIVA with propofol	6 (5%)	4 (3%)	0.75	4 (5%)	3 (3%)	1.00
NSAIDs (flurbiprofen)	28 (22%)	22 (18%)	0.53	15 (17%)	18 (20%)	0.70
Free flap reconstruction	98 (76%)	85 (70%)	0.32	67 (75%)	63 (71%)	0.61
Fentanyl dose; ng/kg/min	23.8 ± 5.6	22.4 ± 6.2	0.07	22.8 ± 5.5	23.3 ± 6.5	0.59

Values are presented as means ± standard deviations, medians [interquartile ranges], or numbers (proportion, %) of patients.

BMI: body mass index

TIVA: total intravenous anesthesia

NSAIDs: nonsteroidal anti-inflammatory drugs