Up-Down Determination of the ED90 of Phenylephrine for Hypotension Prophylaxis in Cesarean Delivery

Up-down Determination of the ED90 of the Initial Rate of Infusion of Phenylephrine for the Prophylaxis of Spinal Induced Hypotension in Parturients Undergoing Cesarean Delivery

This study is designed to determine the ED90 for an infusion of phenylephrine to prevent spinal induced low blood pressure in parturients presenting for an elective cesarean delivery. The up-down methodology (UDM) is commonly used study method to determine the dose of a drug that causes the desired effect in over 90% of the subjects to whom it given. For example: the investigators want to know what is the best dose of phenylephrine (from a range of commonly used doses) to prevent a drop in blood pressure during cesarean delivery ninety times out of one hundred when it is given at that dose. The ED90 is the effective dose at which 90% of subjects will have a "positive" response to a phenylephrine infusion, i.e. no drop in blood pressure. The investigators hypothesize that the ED90 will be between 40 - 60 mcg/min.

The primary outcome measure is the ED90 for phenylephrine infusions that prevents a drop in blood pressure in women undergoing cesarean delivery.

Study Overview

• Status: Terminated
• Conditions: Spinal Induced Hypotension in Cesarean Delivery
• Intervention / Treatment: Drug: Phenylephrine infusion

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Phase 4

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

1. Non-emergent cesarean delivery with planned spinal anesthesia (i.e. elective planned cesarean delivery for malposition, patient choice, cervical pelvic disproportion, previous cesarean delivery and other diagnosis that require a predetermined cesarean delivery)
2. American Society of Anesthesia physical status class I & II (ASA I - Healthy, ASA II - mild and controlled systemic disease, eg. controlled essential hypertension)
3. Age ≥ 18 years (Standard within the obstetrical literature)
4. Term gestational age
5. English-speaking

Exclusion Criteria:

1. Morbid Obesity (Body Mass Index ≥ 45 kg/m2) (Morbidly obese parturients require a dose of local anesthetic less than the standardized dose in this study, typically have an exaggerated response to vasopressors, and the blood pressure cuff occasionally needs to be replaced by an intra-arterial catheter due to limitations in size)
2. Height < 5'0" (Women < 5'0" are likely to require a dose of local anesthetic less than the standardized dose in this study)
3. Laboring women
4. Urgent or emergency cesarean delivery
5. Hypertensive disease of pregnancy
6. Severe maternal cardiac disease
7. Subjects on monoamine oxidase inhibitors (MAOI's) or tricyclic antidepressants
8. Fetal anomalies or intrauterine fetal death
9. Failed spinal anesthesia
10. Subject enrollment in another study involving a study medication within 30 days of CD
11. Any other physical or psychiatric condition which may impair their ability to cooperate with study data collection

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: Quadruple

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 1	Drug: Phenylephrine infusion; Up-down, biased coin design

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effective Dose of Phenylephrine at Which 90% of Subjects Have no Spinal Induced Hypotension	The effective dose at which 90% of subjects will have a "positive" response to a phenylephrine infusion, i.e. no spinal induced hypotension. We hypothesize that the ED90 will be between 40 - 60 mcg/min.	Spinal administration until delivery

Collaborators and Investigators

• Sponsor: IWK Health Centre

Study record dates

Study Major Dates

• Study Start: November 1, 2008
• Primary Completion (Actual): February 1, 2009
• Study Completion (Actual): July 1, 2009

Study Registration Dates

• First Submitted: November 19, 2008
• First Submitted That Met QC Criteria: November 21, 2008
• First Posted (Estimate): November 24, 2008

Study Record Updates

• Last Update Posted (Actual): April 23, 2018
• Last Update Submitted That Met QC Criteria: March 22, 2018
• Last Verified: March 1, 2018

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypotension; Physiological Effects of Drugs; Adrenergic Agents; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Autonomic Agents; Peripheral Nervous System Agents; Protective Agents; Adrenergic alpha-Agonists; Adrenergic Agonists; Cardiotonic Agents; Respiratory System Agents; Sympathomimetics; Vasoconstrictor Agents; Mydriatics; Nasal Decongestants; Adrenergic alpha-1 Receptor Agonists; Phenylephrine; Oxymetazoline
• Other Study ID Numbers: IWK-4462-2008