Table 4.

Meta-analysis of the incidence of adverse events.

Adverse events	Number of studies	Intervention group		Control group		I 2	RR (95% CI)	P
		Cases	Sample size	Cases	Sample size
Respiratory depression	2	5	100	13	100	0.0%	0.39 (0.14, 1.04)	0.061
Bradycardia	2	3	100	14	100	44.7%	0.25 (0.04, 1.78)	0.167
Hypotension	5	11	310	32	311	0.0%	0.40 (0.21, 0.77)	0.006*
Hypoxemia	3	16	190	27	191	42.3%	0.51 (0.18, 1.48)	0.219
Dizziness	1	0	60	2	60	0.0%	0.20 (0.01, 4.08)	0.296
Nausea or vomiting	7	15	500	53	501	0.0%	0.30 (0.17, 0.52)	0.000*
Abdominal distension	2	11	150	26	151	75.3%	1.05 (0.05, 20.66)	0.974
Coughing	2	5	190	21	190	0.0%	0.24 (0.09, 0.62)	0.003*
Restlessness	2	3	190	10	190	0.0%	0.30 (0.08, 1.08)	0.066

RR, risk ratio; CI, confidence interval; ^*P < 0.05.