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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00796328
Recruitment Status : Terminated (Results Invalid, study closed, analysis cannot proceed.)
First Posted : November 24, 2008
Results First Posted : April 21, 2014
Last Update Posted : April 23, 2018
Information provided by (Responsible Party):
Ronald George, IWK Health Centre

Brief Summary:

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.

Condition or disease Intervention/treatment Phase
Spinal Induced Hypotension in Cesarean Delivery Drug: Phenylephrine infusion Phase 4

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 45 participants
Intervention Model: Single Group Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: 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
Study Start Date : November 2008
Actual Primary Completion Date : February 2009
Actual Study Completion Date : July 2009

Arm Intervention/treatment
Experimental: 1 Drug: Phenylephrine infusion
Up-down, biased coin design

Primary Outcome Measures :
  1. Effective Dose of Phenylephrine at Which 90% of Subjects Have no Spinal Induced Hypotension [ Time Frame: Spinal administration until delivery ]
    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.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes

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

Responsible Party: Ronald George, Primary Investigator, MD, FRCPC, Assistant Professor, IWK Health Centre Identifier: NCT00796328     History of Changes
Other Study ID Numbers: IWK-4462-2008
First Posted: November 24, 2008    Key Record Dates
Results First Posted: April 21, 2014
Last Update Posted: April 23, 2018
Last Verified: March 2018

Additional relevant MeSH terms:
Vascular Diseases
Cardiovascular Diseases
Cardiotonic Agents
Autonomic Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Vasoconstrictor Agents
Nasal Decongestants
Respiratory System Agents
Adrenergic alpha-1 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Protective Agents