Wavelet and pain rating index for inhalation anesthesia: A randomized controlled trial

Table 1 Baseline demographic and clinical characteristics of the study participants

	SBP group, n = 21	WLi group, n = 21	PRi group, n = 20	P value
Sex, male/female	13/8	12/9	10/10	0.742
Age in yr	54 ± 6	53 ± 5	52 ± 5	0.747
BMI in kg/m2	24.5 ± 1.8	24.1 ± 1.6	24.0 ± 1.6	0.547
ASA class, I/II	16/5	17/4	15/5	0.891
Duration of surgery in min	134 ± 19	135 ± 12	137 ± 14	0.751
Duration of anesthesia in min	169 ± 18	170 ± 14	171 ± 17	0.920

Values are given as mean ± standard deviation or absolute numbers. ASA: American Society of Anesthesiologists; BMI: Body mass index; PRi: Pain rating index; SBP: Systolic blood pressure; WLi: Wavelet index.

Table 2 Anesthesia recovery time, extubation time and sevoflurane consumption

	SBP group, n = 21	WLi group, n = 21	PRi group, n = 20	P value
Anesthesia recovery time in min	25.1 ± 2.2	19.7 ± 2.2a	20.6 ± 2.1a	< 0.001
Extubation time in min	26.6 ± 2.1	21.0 ± 2.2a	21.6 ± 2.6a	< 0.001
Sevoflurane consumption in mL	33.1 ± 2.1	26.7 ± 4.4a	28.9 ± 3.5a	< 0.001

Values are presented as mean ± standard deviation.

^aP < 0.05 vs systolic blood pressure group. Anesthesia recovery time: Time from discontinuation of sevoflurane to spontaneous eye opening; Extubation time: Time from discontinuation of sevoflurane to extubation. PRi: Pain rating index; SBP: Systolic blood pressure; WLi: Wavelet index.

Table 3 Systolic blood pressure and heart rate measured at 13 major time points during general anesthesia

Time point	Systolic blood pressure, mmHg			Heart rate, beats/min
	SBP group	WLi group	PRi group	SBP group	WLi group	PRi group
Baseline	125 ± 9	121 ± 8	122 ± 11	73 ± 9	71 ± 7	75 ± 9
Five min after tracheal intubation	109 ± 7	106 ± 4	107 ± 9	67 ± 10	66 ± 5	68 ± 10
Placement in prone position	110 ± 6	106 ± 4	109 ± 7	65 ± 10	65 ± 5	66 ± 7
Incision	112 ± 5	108 ± 5	112 ± 10	66 ± 7	64 ± 5	67 ± 8
Vertebral plate exposure	114 ± 6	115 ± 4	115 ± 12	67 ± 6	67 ± 6	68 ± 5
Placement of pedicle screws	118 ± 7	120 ± 8	118 ± 8	67 ± 8	69 ± 5	70 ± 5
Spinal canal decompression	132 ± 13	136 ± 9	134 ± 11	71 ± 97	73 ± 5	74 ± 5
Interbody fusion	126 ± 9	128 ± 10	127 ± 10	72 ± 12	72 ± 6	73 ± 6
Placement of the fixed link	121 ± 7	123 ± 9	123 ± 10	70 ± 12	71 ± 5	73 ± 6
Placement of drainage tube	119 ± 7	122 ± 7	122 ± 9	70 ± 11	71 ± 5	73 ± 6
Skin closure	126 ± 10	128 ± 9	128 ± 10	72 ± 11	73 ± 6	76 ± 6
Placement in recovery position	131 ± 7	130 ± 8	131 ± 10	76 ± 10	78 ± 4	80 ± 5
Tracheal extubation	132 ± 8	131 ± 9	131 ± 11	78 ± 10	79 ± 7	82 ± 6

Values are given as mean ± standard deviation. There were no significant differences in systolic blood pressure or heart rate among the three groups at any time point. PRi: Pain rating index; SBP: Systolic blood pressure; WLi: Wavelet index.

Table 4 Wavelet index and pain rating index measured at 13 major time points during general anesthesia

Time points	Wavelet index, 0-100			Pain rating index, 0-100
	SBP group	WLi group	PRi group	SBP group	WLi group	PRi group
Baseline	99.4 ± 1.2	99.5 ± 1.0	99.9 ± 0.7	85.9 ± 2.8	87.1 ± 1.8	87.5 ± 2.7
Five min after tracheal intubation	44.4 ± 3.9	44.4 ± 2.2	45.3 ± 3.2	57.0 ± 5.8	59.5 ± 4.6	58.9 ± 3.4
Placement in prone position	45.3 ± 2.2	46.1 ± 2.6	45.9 ± 2.3	55.6 ± 4.0	60.4 ± 3.6a	59.2 ± 3.8a
Incision	45.5 ± 2.3	46.7 ± 2.4	46.7 ± 1.4	55.6 ± 4.3	61.5 ± 3.6a	59.5 ± 2.9a
Vertebral plate exposure	46.2 ± 2.4	48.4 ± 4.3a	48.5 ± 1.8a	56.3 ± 4.2	62.3 ± 2.6a	60.1 ± 3.9a
Placement of pedicle screws	47.5 ± 2.4	50.0 ± 4.5a	49.5 ± 2.7	56.1 ± 3.8	62.9 ± 2.3a	60.8 ± 3.9a
Spinal canal decompression	50.9 ± 4.4	55.0 ± 3.0a	53.9 ± 1.7a	60.8 ± 4.0	66.5 ± 1.8a	63.9 ± 3.2a,b
Interbody fusion	50.0 ± 4.1	52.3 ± 2.6a	51.9 ± 2.1a	59.7 ± 2.8	64.0 ± 3.6a	61.7 ± 2.3a,b
Placement of the fixed link	48.1 ± 2.9	51.5 ± 2.9a	50.7 ± 1.9a	58.8 ± 3.6	63.1 ± 3.0a	60.2 ± 2.8b
Placement of drainage tube	48.5 ± 3.2	51.8 ± 2.3a	50.2 ± 2.3a	58.1 ± 3.9	63.2 ± 3.4a	60.3 ± 3.1b
Skin closure	57.8 ± 4.9	60.0 ± 3.3	59.1 ± 1.2	65.9 ± 5.1	69.0 ± 1.8a	68.6 ± 1.8a
Placement in recovery position	83.4 ± 6.8	84.6 ± 4.3	86.4 ± 5.3	76.6 ± 5.0	78.1 ± 2.0	80.9 ± 2.7a,b
Tracheal extubation	98.3 ± 1.5	97.2 ± 2.4	98.4 ± 2.6	87.0 ± 2.7	88.0 ± 2.9	87.9 ± 2.5

Values are given as mean ± standard deviation.

^aP < 0.05 vs systolic blood pressure group.

^bP < 0.05 vs wavelet index group. PRi: Pain rating index; SBP: Systolic blood pressure; WLi: Wavelet index.

Table 5 Intraoperative unwanted events and interventions

	SBP group, n = 21	WLi group, n = 21	PRi group, n = 20	P value
All unwanted events	26 (1.24)	16 (0.76)	14 (0.70)	0.101
Hypertension	14 (0.67)	7 (0.33)	9 (0.45)	0.238
Hypotension	6 (0.29)	3 (0.14)	2 (0.10)	0.267
Tachycardia	4 (0.19)	3 (0.14)	3 (0.15)	0.905
Bradycardia	2 (0.10)	3 (0.14)	0 (0)	0.239
Nicardipine	2 (0.10)	9 (0.43)a	12 (0.60)a	0.024
Esmolol	4 (0.24)	3 (0.14)	4 (0.20)	0.890
Ephedrine	2 (0.10)	3 (0.14)	2 (0.10)	0.868
Atropine	4 (0.19)	3 (0.14)	0 (0)	0.253

Data are presented as n (number per patient).

^aP < 0.05 vs systolic blood pressure group. PRi: Pain rating index; SBP: Systolic blood pressure; WLi: Wavelet index.

Table 6 Intraoperative/postoperative adverse events and postoperative visual analog scale for pain

	SBP group, n = 21	WLi group, n = 21	PRi group, n = 20	P value
PONV	4 (0.19)	2 (0.10)	3 (0.16)	0.684
Agitation	3 (0.14)	0 (0)	2 (0.10)	0.224
Respiratory depression	0 (0)	0 (0)	0 (0)	1
Intraoperative awareness	0 (0)	0 (0)	0 (0)	1
Pain VAS0h	0 (0-2)	0 (0-2)	0 (0-2)	0.766
Pain VAS1/2h	2 (0-4)	3 (0-4)	2 (0-4)	0.122

Data for adverse events are presented as n (number per patient). Data for visual analog scale for pain are presented as median (range). The visual analog scale for pain ranged from 0 to 10, with 0 representing no pain and 10 representing maximum intensity of pain. PONV: Postoperative nausea and vomiting; PRi: Pain rating index; SBP: Systolic blood pressure; VAS: Visual analog scale; WLi: Wavelet index.