Ideal Dose of Phenylephrine to Treat Low Blood Pressure During Cesarean Section

Study Description

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Brief Summary:

The purpose of this study is to determine the minimum effective bolus dose of phenylephrine to prevent post-spinal hypotension in Cesarean section in 95 % of our patients. An adequate response will be defined as the absence of hypotension or nausea/vomiting during the period from induction of spinal anesthesia to uterine incision prior to fetal delivery.

Condition or disease	Intervention/treatment	Phase
Hypotension; Nausea	Drug: phenylephrine	Not Applicable

Detailed Description:

The purpose of this study is to determine the minimum effective bolus dose of phenylephrine to prevent post-spinal hypotension in CS in 95 % of our patients. The study will be conducted in a randomized double-blinded fashion. This dose-response study will be conducted as per the up-down sequential allocation method, modified by the Narayana rule, designed to cluster the results around the ED95.

Blood pressure will be monitored every minute from intrathecal injection to the delivery of the child. Phenylephrine will be administered every time the blood pressure is equal to or lower than the control value.Hypotension will be defined as a SBP less than 80 % of the baseline value, in which case the treatment will be a failure. Hypertension will be defined as a SBP more than 120 % of baseline value. If a patient presents hypertension for two consecutive measurements, the case will be considered a drop out.An adequate response will be defined as the absence of hypotension or nausea/vomiting during the period from induction of spinal anesthesia to uterine incision prior to fetal delivery.

The results of this study will define the minimum effective dose of phenylephrine to prevent post-spinal hypotension and nausea/vomiting secondary to hypotension in Cesarean section, thus optimizing the safety profile with respect to maternal and fetal side effects of this vasopressor.

Study Design

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Study Type :	Interventional (Clinical Trial)
Enrollment :	50 participants
Allocation:	Randomized
Intervention Model:	Single Group Assignment
Masking:	Double
Primary Purpose:	Prevention
Official Title:	Phenylephrine Dose-Finding Study to Minimize Hypotension Due to Spinal Anesthesia for Cesarean Section
Study Start Date :	August 2006
Actual Study Completion Date :	December 2006

Arms and Interventions

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

Outcome Measures

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

Primary Outcome Measures :

1. The primary outcome will be the minimum dose of phenylephrine which effectively prevents both hypotension and nausea/vomiting between intrathecal injection of the local anesthetic and delivery of the fetus.

Secondary Outcome Measures :

1. Maternal Demographics: Maternal age-weight-height
2. Nausea and Vomiting
3. Time of intrathecal injection, skin incision, uterine incision, and delivery
4. Total dose of phenylephrine
5. Hypertension (> 120 % of baseline)
6. Bradycardia (< 50 bpm)
7. Upper sensory level of anesthesia by pinprick upon delivery
8. Umbilical artery and vein blood gases

Eligibility Criteria

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

Criteria

Inclusion Criteria:

• Elective CS under spinal anesthesia
• Normal singleton pregnancy beyond 36 weeks gestation
• ASA physical status I/II
• Weight 50-100 kg, height 150-180 cm
• Age over 18 years

Exclusion Criteria:

• Patient refusal
• Allergy or hypersensitivity to phenylephrine
• Preexisting or pregnancy-induced hypertension
• Cardiovascular or cerebrovascular disease
• Fetal abnormalities
• History of diabetes, excluding gestational diabetes

Contacts and Locations

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Locations

Canada, Ontario
Mount Sinai Hospital
Toronto, Ontario, Canada, M5G 1X5

Sponsors and Collaborators

Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Investigators

Principal Investigator:	Jose CA Carvalho, MD PhD	Department of Anesthesia and Pain Management, Mount Sinai Hospital, University of Toronto

More Information

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

ClinicalTrials.gov Identifier:	NCT00379691 History of Changes
Other Study ID Numbers:	06-01; 06-0186-E
First Posted:	September 22, 2006
Last Update Posted:	March 21, 2007
Last Verified:	March 2007

Keywords provided by Samuel Lunenfeld Research Institute, Mount Sinai Hospital:

spinal; Cesarean section; hypotension	nausea; vomiting; phenylephrine

Additional relevant MeSH terms:

Nausea; Hypotension; Signs and Symptoms, Digestive; Signs and Symptoms; Vascular Diseases; Cardiovascular Diseases; Phenylephrine; Oxymetazoline; Cardiotonic Agents; Mydriatics; Autonomic Agents; Peripheral Nervous System Agents	Physiological Effects of Drugs; Sympathomimetics; 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