Intravenous Ondansetron to Attenuate the Hypotensive, Bradycardic Response to Spinal Anesthesia in Healthy Parturients

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: NCT01414777
Recruitment Status : Unknown
Verified August 2011 by University of Virginia.
Recruitment status was:  Enrolling by invitation
First Posted : August 11, 2011
Last Update Posted : August 11, 2011
Information provided by:
University of Virginia

Brief Summary:

The investigators hypothesize that given prophylactically, intravenous ondansetron will attenuate the drop in blood pressure and heart rate frequently seen after spinal anesthesia.

Eighty-six American Society of Anesthesiologists (ASA) physical status I or II in preoperative patient assessment, parturients age of 18 to 45 years scheduled to undergo elective caesarean section will be enrolled.

Patients will be randomized to 2 groups: the ondansetron group, receiving 8 mg intravenous ondansetron diluted in 10 mL of saline; or the placebo group, who were administered 10 mL of saline given 5 minutes prior to performing the spinal anesthetic. Investigational Pharmacy will randomize and dispense study drug.

Baseline measurements of vital signs will be taken. Otherwise standard management will then be used:

  • Patients must be NPO for 8 hours
  • Pulse oximetry, EKG monitoring, noninvasive blood pressure at a minimum of every 3 minutes, more frequently if decided by the provider.
  • Standard lumbar puncture in a sitting position the L3-L4 or L4-L5
  • Whitacre pencil-point, 25 gauge
  • Injectate: 2 mL of 0.75% hyperbaric bupivacaine, 100 mcg preservative free morphine, 20 mcg fentanyl
  • Immediately after completing the subarachnoid injection, patients will be laid supine with left lateral uterine displacement

The sensory level of anesthesia will be assessed in the standard fashion every five minutes using ice. The motor component will tested using the Bromage scale for spinal anesthesia (0, no paralysis; 1, inability to lift the thigh [only knee/feet]; 2, inability to flex the knee [only feet]; 3, inability to move any joint in the legs).

Condition or disease Intervention/treatment Phase
Hypotension Pregnancy Drug: ondansetron Drug: placebo Phase 2 Phase 3

Detailed Description:

Over the last 30 years, regional anesthesia has emerged as the method of choice for elective caesarean section because it avoids risks involved in managing the airway of the parturient and has the added significant benefit of mother being awake for the birth of her child. Indeed, this changing practice patterns is thought to have lead to a significant drop in anesthesia related maternal morbidity and mortality.

At the same time, regional anesthesia is associated with both minor and significant risk.

Most common among these effects is hypotension and bradycardia, occurring in 33% and 13% of cases, respectively. In the pregnant patient, supine positioning required for surgery is associated hypotension due to aortocaval compression by the gravid uterus in 8% of patients, even without spinal anesthesia. During caesarean section, the combination of these factors can lead to hypotension include decreased placental blood flow, impaired fetal oxygenation and fetal acidosis. Maternal symptoms of low blood pressures include nausea, vomiting, dizziness, and decreased consciousness. This situation has lead to dozens of publications seeking to prevent or minimize the hypotensive response.

Hypotension after a spinal is initially due to a blockade of sympathetic fibers leading to a drop in systemic vascular resistance. Spinal-induced bradycardia is multifactorial but is in part due to the Bezold-Jarisch Reflex (BJR). This reflex is mediated by serotonin receptors within the wall of the ventricle in response to systemic hypotension. These receptors, the 5HT3 subtype, cause an increase efferent vagal signaling when bound by serotonin released during hypovolemic states, clinically leading to bradycardia and further hypotension.

Ondansetron, a widely used anti-emetic and serotonin antagonist, has been safely used to blunt the BJR, resulting in less bradycardia and hypotension first in animals and later in humans undergoing spinal anesthesia. ,

Use During Pregnancy:

The FDA labels ondansetron as a class B. Studies in pregnant rats and rabbits at doses up to 70 times higher than clinically used doses revealed no evidence of impaired fertility or harm to the fetus due to ondansetron. There are, however, few prospective studies in pregnant women. Nevertheless, the drug is widely used has a long safety history for use in pregnancy and during anesthesia for caesarean section.

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 68 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary Purpose: Prevention
Official Title: IRB-HSR# 14583: Intravenous Ondansetron to Attenuate the Hypotensive, Bradycardic Response to Spinal Anesthesia in Healthy Parturients
Study Start Date : November 2009

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arm Intervention/treatment
Experimental: ondansetron
ondansetron 8 mg IV will be administered prior to placement of the spinal anesthesia
Drug: ondansetron
Ondansetron 8mg IV or placebo will be administered prior to placement of the spinal anesthetic
Other Name: epidural
Placebo Comparator: Placebo
Ondansetron 8 mg IV or Placebo will be administered prior to placement of the spinal anesthestic
Drug: placebo
placebo or ondansetron 8mg IV will be administered prior to placement of the spinal anesthetic
Other Name: epidural

Primary Outcome Measures :
  1. Number of Participants with Adverse Events as a Measure of Safety and Tolerability" [ Time Frame: day 1 ]
    hypotension & bradycardia will be recorded from the placement of the spinal through the end of surgical c-section

Secondary Outcome Measures :
  1. dosage of vasopressors administered [ Time Frame: day one ]
    vasopressors administered during surgery

  2. number of episodes of nausea [ Time Frame: 24 hours after surgery ]
  3. occurrence & intensity of itching [ Time Frame: 24 hours after surgery ]
  4. pain scores reported by the patient [ Time Frame: 24 hours after surgery ]
  5. dosage of anticholinergics administered [ Time Frame: 24 hours after surgery ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Elective Caesarean section
  • Consent to be in the study
  • Age 18-45
  • ASA 1 or 2

Exclusion Criteria:

  • Patient refusal
  • Patients with known allergy to ondansetron will be excluded
  • Contraindications to spinal anesthetic

    • Known Coagulopathy (acquired e.g. anticoagulation or existing such as liver disease; using patient history, physical examination to determine bleeding risks, a platelet count under 100 or a PT INR over 1.4)
    • Severely altered anatomy (e.g. post surgical changes)
    • Existing neurological deficits (Women with a history of migraine or tension headache will be allowed to enroll. More severe conditions with daily life limiting symptoms will be excluded. Examples include epilepsy, pseudotumor cerebri, prior stroke with persistent neurologic deficits, or any motor or sensory neuropathy with existing deficits)
    • Skin infection overlying site

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01414777

United States, Virginia
University of Virginia Health System
Charlottesville, Virginia, United States, 22908
Sponsors and Collaborators
University of Virginia
Principal Investigator: Jordan Hackworth, MD University of Virginia Anesthesiology

FDA Prescribing Information. Web retrieved 7/8/2009 .

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Jordan Hackworth, MD, UVA Department of Anesthesiology Identifier: NCT01414777     History of Changes
Other Study ID Numbers: 14583
First Posted: August 11, 2011    Key Record Dates
Last Update Posted: August 11, 2011
Last Verified: August 2011

Keywords provided by University of Virginia:
Hypotension after spinal anesthesia for C-section

Additional relevant MeSH terms:
Vascular Diseases
Cardiovascular Diseases
Antihypertensive Agents
Central Nervous System Depressants
Physiological Effects of Drugs
Autonomic Agents
Peripheral Nervous System Agents
Gastrointestinal Agents
Dermatologic Agents
Serotonin Antagonists
Serotonin Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Antipsychotic Agents
Tranquilizing Agents
Psychotropic Drugs
Anti-Anxiety Agents