ONDANSETRON AND EFFECTIVE DOSE IN 50% OF SUBJECTS OF PROPHYLACTIC NOREPINEPHRINE INFUSIONS FOR PREVENTING SPINAL ANESTHESIA-INDUCED HYPOTENSION DURING CESAREAN DELIVERY

• Status: Not yet recruiting
• Trial end date: 2021-08-01
• Target enrollment: 0
• Participant gender: Female

Summary

Spinal anesthesia is the preferred technique for elective cesarean section as per ASA guidelines. Hypotension is the main complication of this technique and is secondary to both sympatholysis and its associated decrease in systemic vascular resistance and to the Bezold-Jarisch reflex, which causes hypotension and bradycardia in response to noxious stimuli detected in the cardiac ventricles. In pregnant patients, spinal anesthesia induced hypotension is worsened by compression of the aorta and inferior vena cava by the gravid uterus. In this setting, hypotension could lead to uteroplacental hypoperfusion and fetal distress.

In its 2020 guidelines for enhanced recovery after cesarean section, SOAP states that preventing spinal-induced hypotension is an important strategy to enhance maternal and neonatal outcomes in cesarean delivery

Recent studies showed that 5-hydroxytryptamine-3 receptor antagonists, mostly used as nausea and vomiting prophylaxis agents, also contributed to inhibit the Bezold-Jarisch reflex and its associated hemodynamic consequences. Ondansetron is the most studied molecule in this field.

Many recent studies and meta-analyses show renewed interest in the use of norepinephrine as a first line agent for preventing and treating spinal anesthesia-induced hypotension in obstetric anesthesia practice instead of phenylephrine. Norepinephrine has the advantage of a better cardiac output and cardiac frequency as compared to phenylephrine without any fetal side effect. The combination of ondansetron and phenylephrine for the prevention of spinal anesthesia-induced hypotension has been studied, but not the combination of ondansetron and norepinephrine.

The main objective of this study is to evaluate the sparing effect of a standard dose of ondansetron on norepinephrine consumption during elective cesarean section under spinal anesthesia by determining the effective dose in 50% of subjects (ED50) of a prophylactic norepinephrine infusion after receiving a single dose of 4 mg of ondansetron or a saline control.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Laval University
• Collaborator: CHU de Quebec-Universite Laval
• Treatments: Ondansetron

Criteria

Inclusion Criteria:

• parturients with a singleton pregnancy at term (37 week's gestation and more)

• elective cesarean delivery under spinal anesthesia

• American Society of Anesthesiologists physical status < III

Exclusion Criteria:

• patient refusal

• allergy or hypersensitivity to Norepinephrine or Ondansetron

• Use of monoamine oxidase inhibitors, triptyline or imipramine antidepressants

• Long QT syndrome or another cause of prolonged QT

• significant preexisting maternal disease (cardiovascular or cerebrovascular disease or coagulopathy, diabetes mellitus)

• pre-existing or pregnancy-induced hypertension

• pathological pregnancy (ruptured membranes, pre-eclampsia, placenta praevia, gestational diabetes)

• body mass index < 18 or > 40

• height < 150 or > 180

• fetal abnormalities

• contraindication to spinal anesthesia