Effect of clonidine on the cutaneous silent period during spinal anesthesia

Table 1 Patient and clinical data (n = 30, mean ± SD), n (%)

Patient data, duration of surgery	Group
	Levobupivacaine (n = 30)	Levobupivacaine + Clonidine (n = 30)
Age (yr), mean ± SD	43.5 ± 9.2	46.7 ± 10.3
BMI (kg /m2), mean ± SD	23.3 ± 0.9	23.5 ± 0.5
Male gender	26 (86.7)	26 (86.7)
Female gender	4 (13.3)	4 (13.3)
ASA PS 2	10 (33.3)	8 (26.7)
Hypertension	3 (10.0)	4 (13.3)
Hernia localization, left side	17 (56.7)	16 (53.3)
Duration of surgery (min), mean ± SD	61.2 ± 12.9	62.8 ± 20.6

ASA PS: American Society of Anesthesiologists physical status; BMI: Body mass index.

Table 2 Cutaneous silent period and latency of cutaneous silent period before, during and after spinal anesthesia (mean ± SD)

	Levobupivacaine group(n = 30)	Levobupivacaine + Clonidine group(n = 30)	P1	P2	P3
CSP latency (ms) preoperative	108.2 ± 11.6	107.2 ± 11.6	0.737
CSP latency (ms) Bromage 0	130.3 ± 10.2	144.7 ± 8.3	< 0.001a	< 0.001e	< 0.001e
CSP latency (ms) 6 h	110.4 ± 10.6	132.3 ± 9.7	< 0.001b	0.459	< 0.001f
CSP latency (ms) 24 h	108.0 ± 10.6	107.5 ± 11.5	0.862	0.933	0.926
CSP (ms) preoperative	62.1 ± 9.5	61.3 ± 6.2	0.691
CSP (ms) Bromage 0	44.8 ± 8.1	40.2 ± 3.8	0.007c	< 0.001g	0.007g
CSP (ms) 6 h	59.6 ± 9.8	44.5 ± 5.0	< 0.001d	0.325	< 0.001h
CSP (ms) 24 h	63.2 ± 9.9	62.9 ± 5.9	0.892	0.681	0.315

¹P values for differences between groups, independent t-test;

²P values for differences compared to preoperative values in Levobupivacaine group, dependent t-test;

³P values for differences compared to preoperative values in Levobupivacaine + Clonidine group, dependent t-test.

^aIndicates significant differences in CSP latency between groups at the time point Bromage 0;

^bIndicates significant differences in CSP latency between groups 6 h after intrathecal administration of the solution;

^cIndicates significant differences in CSP duration between groups at the time point Bromage 0;

^dIndicates significant differences in CSP duration between groups 6 h after intrathecal administration of the solution;

^eIndicates significant differences in CSP latency comparing the preoperative and postoperative values at time point Bromage 0;

^fIndicates significant differences in CSP latency comparing the preoperative and postoperative values 6 h after intrathecal administration of the solution;

^gIndicates significant differences in CSP duration comparing the preoperative and postoperative values at time point Bromage 0;

^hIndicates significant differences in CSP duration comparing the preoperative and postoperative values 6 h after intrathecal administration of the solution. CSP: Cutaneous silent period.

Table 3 Perioperative characteristics of subarachnoid block, duration of perioperative analgesia and amount of nonsteroidal anti-inflammatory drug administration through whole time (over 24 h) - independent t-test (mean ± SD)

	Levobupivacaine group(n = 30)	Levobupivacaine + Clonidine group(n = 30)	P
Regression time of the motor block (Bromage 0) - operated side	162.3 ± 25.6	285.3 ± 55.2	< 0.001
The time of sense regression in S1 dermatome - operated side (pinprick test)	195.0 ± 22.4	326.3 ± 49.4	< 0.001
Duration of analgesia after SAB application	192.3 ± 20.3	364.3 ± 53.3	< 0.001
NSAID (iv.) 1st time (min)	205.3 ± 22.2	377.0 ± 51.6	< 0.001
NSAID (iv.) 2nd time (min)	388.3 ± 38.4	593.8 ± 54.9	< 0.001

iv.: Intravenous; NSAID: Nonsteroidal anti-inflammatory drug; S1: Sacral; SAB: Subarachnoid block.