ST depression at caesarean section and the relation to oxytocin dose. A randomised controlled trial.
OBJECTIVE
To investigate whether there is a difference in occurrence of electrocardiogram changes suggestive of myocardial ischaemia between two different doses of oxytocin.


METHODS
Double-blind randomised controlled trial.


METHODS
University hospital in Sweden.


METHODS
A total of 103 healthy women undergoing elective caesarean section under spinal anaesthesia.


METHODS
The participants were randomised to 5 or 10 units of oxytocin, given as an intravenous bolus. A Holter monitor was used to record electrocardiograms and non invasive blood pressure and heart rate (HR) was monitored. A blood sample was obtained 12-hour postoperatively.


METHODS
Depression of the ST segment.


RESULTS
symptoms, Troponon I levels, mean arterial pressure (MAP), HR and blood loss.


RESULTS
There was a significant difference in occurrence of ST depressions associated with oxytocin administration, 4 (7.7%) with 5 and 11 (21.6%) with 10 units, P < 0.05. The absolute risk reduction was 13.9% (95% confidence interval, 0.5-27.3). Decrease of mean MAP from baseline to 2 minutes differed, being 9 mmHg in the 5 unit group and 17 mmHg in the 10 unit group (P < 0.01). The increase in mean HR did not differ. Troponin I levels were increased in four subjects (3.9%). There were no differences in occurrence of symptoms, Troponin I levels, or estimated blood loss.


CONCLUSIONS
ST depressions were associated with oxytocin administration significantly more often in subjects receiving 10 units compared with 5 units. Interventions to prevent hypotension during caesarean section may reduce the occurrence of ST depressions on electrocardiograms.
Department of Women's and Children's Health Uppsala University, Uppsala, Sweden. maria.jonsson@kbh.uu.se
M
M
Jonsson
U
U
Hanson
C
C
Lidell
S
S
Nordén-Lindeberg
D000328:Adult; D000773:Anesthesia, Obstetrical / Q000379:methods; D000775:Anesthesia, Spinal / Q000379:methods; D001145:Arrhythmias, Cardiac / Q000097:blood / Q000139:chemically induced* / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects; D002585:Cesarean Section; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory / Q000187:drug effects; D005260:Female; D006801:Humans; D010120:Oxytocics / Q000008:administration & dosage / Q000009:adverse effects*; D010121:Oxytocin / Q000008:administration & dosage / Q000009:adverse effects*; D011247:Pregnancy; D019210:Troponin I / Q000378:metabolism
D010120:Oxytocics; D019210:Troponin I; D010121:Oxytocin