Effect of low dose of intrathecal pethidine on the incidence and intensity of shivering during cesarean section under spinal anesthesia: a randomized, placebo-controlled, double-blind clinical trial

Figures & data

Table 1 Comparison of demographic variables and paraclinical data of the participants in three groups before the intervention

Variable	Placebo group, N=50	Pethidine 5 mg group, N=50	Pethidine 10 mg group, N=50	P-value
Age; mean ± SD	31.8±4.7	31±5.5	31.5±5.6	0.76
Duration of surgery; mean ± SD	55.2±15.1	57.6±15.9	53.8±13.7	0.44
Preoperative hemoglobin level; mean ± SD	12.5±1.2	12.5±1.1	12.5±1.2	0.85
Preoperative hematocrit level; mean ± SD	38.1±3.7	37.7±3	37.8±3.3	0.71

Note: Analysis of variance test was used to compare the variables among the three groups.

Abbreviation: SD, standard deviation.

Figure 1 Group randomization according to CONSORT 2010.

Abbreviation: CONSORT, Consolidated Standards of Reporting Trials.

Figure 2 Comparison of the trend of systolic blood pressure during the study among control and intervention groups.

Notes: Analysis was done by repeated measurement. 5 mg pethidine vs placebo: P=0.2, 10 mg pethidine vs placebo: P=0.2, 5 mg pethidine vs 10 mg pethidine: P=0.5.

Figure 3 Comparison of the trend of diastolic blood pressure during the study among control and intervention groups.

Notes: Analysis was done by repeated measurement. 5 mg pethidine vs placebo: P=0.7, 10 mg pethidine vs placebo: P=0.7, 5 mg pethidine vs 10 mg pethidine: P=0.7.

Figure 4 Comparison of the trend of pulse rate during the study among control and intervention groups.

Notes: Analysis was done by repeated measurement. 5 mg pethidine vs placebo: P=0.8, 10 mg pethidine vs placebo: P=0.9, 5 mg pethidine vs 10 mg pethidine: P=0.7.

Figure 5 Comparison of the trend of core body temperature during the study among control and intervention groups.

Notes: Analysis was done by repeated measurement. 5 mg pethidine vs placebo: P=0.2, 10 mg pethidine vs placebo: P=0.4, 5 mg pethidine vs 10 mg pethidine: P=0.8.

Table 2 Comparison of outcomes in the three groups after the intervention

Variable	Placebo group, N=50	Pethidine 5 mg group, N=50	Pethidine 10 mg group, N=50	Total, N=150	P-value (95% CI)
Intensity of shivering; n (%)					<0.001*
0 (no shivering)	25 (50)	39 (78)	48 (96)	112 (74.7)	(67.7–81.6)
1	17 (34)	9 (18)	2 (4)	28 (18.7)	(12.5–24.9)
2	7 (14)	2 (4)	0	9 (6)	(2.2–9.8)
3	1 (2)	0	0	1 (0.7)	(0–2)
4 (highest)	0	0	0	0	–
Intensity of shivering
Median (25th–75th quartile)	0.5 (0–1)	0 (0–0)	0 (0–0)	0 (0–1)	0.009a,‡
Mean (±SD)	0.68 (0.79)	0.26 (0.53)	0.04 (0.2)	32 (0.62)	<0.001b
					0.02c

Notes:

* Kruskal–Wallis test was used to compare rank of shivering intensity.

‡ Mann–Whitney U-test was used, and P-value corrected by Bonferroni correction for multiple comparison. Analysis of variance test was used to compare quantitative variables among three groups.

a Placebo group vs pethidine 5 mg group;

b placebo group vs pethidine 10 mg group;

c pethidine 5 mg group vs pethidine 10 mg group.

Abbreviations: CI, confidence interval; SD, standard deviation.

Table 3 Adverse effects and drug used as rescue treatment in three study groups

Variable	Placebo group, N=50	Pethidine 5 mg group, N=50	Pethidine 10 mg group, N=50	Total, N=150	P-value (95% CI)
Hypotension; n (%)	34 (68)	33 (66)	37 (74)	104 (69.3)	0.66 (61.9–76.7)
Bradycardia; n (%)	3 (6)	0 (0)	1 (2)	4 (2.7)	0.17 (0.1–5.3)
Nausea; n (%)	19 (38)	25 (50)	27 (54)	71 (47.3)	0.25 (39.3–55.3)
Vomiting; n (%)	6 (12)	13 (26)	13 (26)	32 (21.3)	0.14 (14.7–27.8)
Pruritus; n (%)	0 (0)	3 (6)	13 (26)	16 (10.7)	0.01 (5.7–15.6)
Prescripted ephedrine; n (%)	34 (68)	33 (66)	37 (74)	104 (69.3)	0.09 (61.9–76.7)
Prescripted atropine; n (%)	3 (6)	0 (0)	1 (2)	4 (2.7)	0.17 (0.1–5)
Prescripted ondansetron; n (%)	8 (16)	18 (36)	19 (38)	45 (30)	0.03 (22.7–37.3)
Prescripted pethidine; n (%)	8 (16)	2 (4)	0 (0)	10 (6.7)	0.004 (3–10)

Abbreviation: CI, confidence interval.