Preventing Hypotension in Parturients With an Elevated Body Mass Index (BMI)

A Double Blind Randomized Controlled Trial of Phenylephrine for the Prevention of Spinal Induced Hypotension in Obese Parturients

Previous research regarding the use of phenylephrine has excluded obese subjects (BMI >35). This subgroup of patients represents a large portion of the obstetric patient population locally and nationally. It is unclear whether previous research should be extrapolated to the obese patient population. This study is being done to compare the incidence of hypotension, intraoperative nausea and vomiting, and neonatal acidosis between obese patients who receive a prophylactic phenylephrine infusion versus those who receive phenylephrine boluses for the treatment of established hypotension. This study will help us determine whether using a phenylephrine infusion or a phenylephrine bolus is the best way to prevent/treat spinal induced hypotension during cesarean deliveries in obese patients.

Inclusion Criteria:

• English speaking
• ASA Physical Status I-II
• Non-laboring women
• Single gestations ≥ 36 weeks
• Obese women (Body Mass Index 35 - 55 kg/m2)
• Non-emergent CD under spinal anesthesia

Exclusion Criteria:

• Height < 5'0"
• Antiemetic drug use in the 24 hours prior to CD
• Allergy to phenylephrine, or any other standardized medication
• Hypertensive disease of pregnancy (i.e. mild & severe preeclampsia)
• Chronic hypertension receiving antihypertensive treatment
• Severe Cardiac disease in pregnancy with marked functional limitations
• Patients on Monoamine Oxidase Inhibitors or Tricyclic Antidepressants
• Subject enrollment in another study involving a study medication within 30 days of CD
• Any other physical or psychiatric condition which may impair their ability to cooperate with study data collection