Table 4.

Incidence of Adverse Reactions in Patients Among Four Groups (n, %)

Group	Number	Nausea and Vomiting	Respiratory Depression	Injection Pain
P	44	2 (4.5%)	4 (9.1%)	5 (11.4%)
C2	38	0a	0a	0a
C3	36	0a	0a	0a
C4	31	0a	4 (12.9%)b,c	0a

Notes: Compared to the group P, ^aP < 0.05; Compared to the group C2, ^bP < 0.05; Compared to the group C3, ^cP < 0.05.