Combination of Intravenous Ondansetron and Intravenous Glycopyrrolate Versus Intravenous Ondansetron and Intramuscular Glycopyrrolate for Reduction of Post-spinal Hypotension in Cesaraen Section: A Randomized Double-Blinded Study.

Background: In parturients, post-spinal hypotension is common due to loss of sympathetic tone. Compression of the inferior vena cava by the gravid uterus further aggravates it. Various pharmacologic and non-pharmacologic techniques are used to reduce the severity of hypotension. Ondansetron, a selective 5-hydroxytryptamine receptor antagonist, nullifies the Bezold Jarisch reflex response to spinal anaesthesia and glycopyrrolate, an anti-cholinergic, has been used to prevent post-spinal hypotension. We estimated the efficacy of intravenous (IV) glycopyrrolate plus IV ondansetron versus intramuscular (IM) glycopyrrolate plus IV ondansetron to reduce post-spinal hypotension in caesarean section. We compared hypotension episodes and the total ephedrine dose required to treat hypotension among the groups.

Methods: Ninety parturients undergoing elective and emergency caesarean section under spinal anaesthesia were randomly assigned into three groups of 30 each. Group A received prophylactic IV glycopyrrolate 0.2mg plus IV ondansetron 4mg, Group B received IM glycopyrrolate 0.2mg plus IV ondansetron 4mg and Control Group C received 10ml of normal saline plus IV ondansetron 4mg. The total ephedrine dose required to treat hypotension (primary objective), incidence of hypotension and maternal heart rate variations were analysed.

Results:  Group B required significantly less vasopressor as compared to Group C (6.4286mg±1.6036 vs 8.7mg±3.6288, p=0.0420). There is no statistically significant difference between Group A and Group C for vasopressor requirement (7.8750mg±2.8723 vs 8.7mg±3.6288, p=0.5425). Maternal heart rate in Group A was higher at the eighth minute compared to Group B and Group C (100.2±21.3 vs 95.3±14.4 vs 86.2±19.0, p=0.015). Incidence of hypotension was same in all the groups (46.7% vs 46.7% vs 51.1%, p=0.491) and complications among groups were comparable.

Conclusion:  Prophylactic use of IM glycopyrrolate plus IV ondansetron decreases total vasopressor required to treat hypotension but does not decrease the incidence of hypotension. Prophylactic use of IV glycopyrrolate increases maternal heart rate.