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Cardiac Effects of Oxytocin Administrated During Cesarean Section, Signs of Myocardial Ischemia

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: NCT00777166
Recruitment Status : Completed
First Posted : October 22, 2008
Last Update Posted : March 14, 2014
Information provided by (Responsible Party):
Uppsala University

Brief Summary:

Oxytocin has cardio vascular effects as hypotension, tachycardia and possibly coronary spasm. The uterotonic effect of the drug is used during cesarean section, to minimize blood loss.ECG changes suggestive of cardiac ischemia (ST depression) has been showed in previous studies of patients undergoing cesarean section i regional anaesthesia. The effect of oxytocin on this outcome has not been investigated to any extent.

In the current study, we tested the hypothesis that there was no difference in occurrence of ECG changes (ST segment depression) between two doses of oxytocin. Participants were randomized to receive either 5 or 10 units of oxytocin in a double blinded fashion.

Main outcome measure is occurrence of significant ST depression on ECG. Secondary outcome measures are mean arterial pressure, heart rate, blood loss, symptoms as chest pain, shortness of breath and feeling of heaviness on the chest.

Condition or disease Intervention/treatment Phase
Myocardial Ischemia Hypotension Bloodloss Drug: oxytocin Phase 4

Detailed Description:

All healthy term participants scheduled to undergo elective caesarean section under spinal anaesthesia at the Department of Obstetrics and Gynecology, University Hospital, Uppsala Sweden and who were > 18 years old, were candidates for inclusion in the study. .

The study was approved by the regional ethics committee and informed written consent was obtained from each participant.

ECGs were recorded by continuous ambulatory ECG (Holter) monitoring (GE Medical systems SEER/MARS, UK) during the peroperative period utilizing leads V3, V5 and avF. As secondary outcomes, symptoms as chest pain, shortness of breath and feeling of heaviness on the chest and, Troponin I levels 12 hours postoperatively, were recorded. Also, as secondary outcomes, differences in blood pressure, heart rate, and blood loss were measured.

Before induction of anaesthesia, patients received 1000 mL of lactated Ringer's solution intravenously. Thereafter an additional 500-1000 mL of lactated Ringer's solution or 500 mL Hydroxyethyl starch was infused if considered needed by the anaesthesiologist.

Spinal anaesthesia was established in the sitting position at lumbal interspace L2/L3 or L3/L4. Non invasive blood pressure (systolic, diastolic and mean arterial pressure, MAP) and heart rate was monitored every 2 minutes, throughout surgery. Oxytocin was given as an intravenous bolus dose immediately after clamping of the umbilical cord. Blood loss during the operation was estimated and recorded. During surgery, any spontaneous complaints by the patients of symptoms as chest pain, shortness of breath and feeling of heaviness on the chest, was recorded as well as duration of symptoms. Episodes of chest pain were assessed with the visual analogue scale (VAS).

Troponin I, as a marker of ischemic myocardial damage, was sampled 12 hours postoperatively.

The incidence of ECG changes related to different doses of intravenous bolus doses of oxytocin (5 and 10 units) during caesarean section is unknown. In a pilot study preceding the present study, 5 units oxytocin were administrated and the incidence of ECG changes was 15%. With the assumption that ECG changes could occur in 50% of subjects receiving 10 units oxytocin and based on 0.8 power to detect a significant difference (P = 0.05, two-sided), 25 patients were required for each study group. An interim analysis performed after inclusion of 50 patients revealed that ECG-changes occured in 8 and 24 % respectively in the two groups of 5 and 10 units of oxytocin. An additional 50 patients were allocated and a second interim analysis planned.

A computer-generated randomisation list with block of four was drawn up by a statistician and given to the pharmacy department who performed the randomisation. The procedure ensured allocation concealment.

All participants, health care providers, investigators and other persons (cardiologist) were blinded to treatment assignment for the duration of the study.

The Statistical Package for Social Sciences (SPSS) for Windows, version 15.0, was used (SPSS, Inc., Chicago, IL, USA). To compare group distributions the chi-squared test or Fisher's exact test was applied and the Mann-Whitney U-test or t-test for continuous variables. A p-value < 0.05 was considered to indicate a significant difference

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 103 participants
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary Purpose: Treatment
Official Title: Phase 4 Study of Oxytocin Used During Cesarean Section
Study Start Date : December 2005
Actual Primary Completion Date : July 2008
Actual Study Completion Date : July 2008

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Cesarean Section
Drug Information available for: Oxytocin

Arm Intervention/treatment
Active Comparator: 1
oxytocin 5 units
Drug: oxytocin
oxytocin 5 units diluted with normal saline to a total volume of 10 mL
Other Names:
  • syntocinon
  • Pitcotin

Active Comparator: 2
oxytocin, 10 units
Drug: oxytocin
oxytocin 10 units diluted with normal saline to at total volume of 10 mL.
Other Names:
  • Syntocinon
  • Pitcotin

Primary Outcome Measures :
  1. ST segment depression on ECG [ Time Frame: 30 minutes ]

Secondary Outcome Measures :
  1. mean arterial blood pressure, heart rate, blood loss and symptoms as chest pain [ Time Frame: 60 minutes ]

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:   Yes

Inclusion Criteria:

  • Healthy women >/= 18 years scheduled to planned cesarean section

Exclusion Criteria:

  • BMI > 35
  • Multiple birth
  • Complications to pregnancy
  • Non proficiency in the Swedish language

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): NCT00777166

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University hospital Uppsala
Uppsala, Sweden
Sponsors and Collaborators
Uppsala University
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Principal Investigator: Ove Axelsson, Professor Uppsala University, Sweden
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Responsible Party: Uppsala University Identifier: NCT00777166    
Other Study ID Numbers: 2004-004929-99
First Posted: October 22, 2008    Key Record Dates
Last Update Posted: March 14, 2014
Last Verified: March 2014
Keywords provided by Uppsala University:
ST depression
cesarean section
blood loss
Additional relevant MeSH terms:
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Myocardial Ischemia
Coronary Artery Disease
Pathologic Processes
Vascular Diseases
Cardiovascular Diseases
Heart Diseases
Coronary Disease
Arterial Occlusive Diseases
Reproductive Control Agents
Physiological Effects of Drugs