Title: Effects of Ephedrine, Phenylephrine and Norepinephrine on Contractility of Human Myometrium and Umbilical Arteries: An In-vitro Study

• Status: Recruiting
• Trial end date: 2021-12-01
• Target enrollment: 0
• Participant gender: Female

Summary

Hypotension is one of the most common adverse effects of spinal anesthesia for cesarean deliveries, affecting as many as 55-90% of mothers. Hypotension during cesarean deliveries can have detrimental effects on the mother and neonate. Various vasopressors, such as ephedrine, phenylephrine and more recently norepinephrine, have been used for the prevention and treatment of hypotension at cesarean deliveries.

Ephedrine was historically considered as the gold standard vasopressor for the management of hypotension during cesarean deliveries. This was based on studies in animal models that showed preserved uteroplacental circulation with ephedrine and not with phenylephrine. However, multiple studies in the past several decades have shown that phenylephrine compared with ephedrine results in a more favorable fetal acid-base status. Consequently, the use of phenylephrine for blood pressure management during cesarean deliveries increased. Recently, norepinephrine was introduced in the obstetrical practice for the management of hypotension at cesarean deliveries, due to its ability to maintain maternal cardiac output better than phenylephrine. However, much controversy still exists surrounding the choice of vasopressor in the obstetric population, in large part due to their varying efficacies, and maternal and fetal effects.

Vasopressors used for the treatment of hypotension during cesarean deliveries can have significant direct or indirect effects on the perfusion of uteroplacental and umbilical vessels. Reduction of uteroplacental perfusion and constriction of umbilical arteries can result in fetal acidosis, however, the mechanisms for these effects are unclear. The investigators hypothesize that ephedrine, phenylephrine and norepinephrine have variable effects on the contractility of pregnant myometrium and umbilical arteries due to their variable actions on adrenergic alpha (α) and beta (β) receptors located in these tissues.

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: Samuel Lunenfeld Research Institute, Mount Sinai Hospital
• Treatments: Ephedrine; Norepinephrine; Oxymetazoline; Phenylephrine; Pseudoephedrine

Criteria

Inclusion Criteria:

• Patients who give written consent to participate in this study

• Patients with gestational age 37-41 weeks

• Patients of 19-40 years

• Non-laboring patients, not exposed to exogenous oxytocin

• Patients requiring elective primary or first repeat caesarean delivery

• Patients undergoing caesarean delivery under spinal anesthesia

Exclusion Criteria:

• Patients who refuse to give written informed consent

• Patients who require general anesthesia

• Patients in labor and those receiving oxytocin for induction of labor

• Emergency caesarean delivery in labor

• Patients who have had previous uterine surgery or >1 previous caesarean delivery

• Patients with any condition predisposing to uterine atony

• Patients on medications that could affect myometrial contractility, such as insulin, nifedipine, labetolol or magnesium sulfate.