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. Design Double-blind randomised controlled trial Setting University hospital in Sweden. Population 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. Main outcome measures Depression of the ST segment. Secondary outcomes: 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. Conclusion 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.

Nyckelord

caesarean section

regional anaesthesia

oxytocin

heart

ischemia

hypotension

electrocardiography

MEDICINE

MEDICIN

Obstetrik och gynekologi

Obstetrics and Gynaecology

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