A randomised double-blind trial of minimal bolus doses of oxytocin for elective caesarean section under spinal anaesthesia: Optimal or not?

BACKGROUND: Oxytocin administration regimens are arbitrary and highly subjective. Hence, it is essential to reinvestigate the appropriate dose for effective uterine contraction with minimal bleeding and adverse effects. AIM: To determine the optimal dose of bolus oxytocin for uterine contractions for elective caesarean section under spinal anaesthesia. METHODS: Ninety term mothers (37 to 41 weeks) undergoing caesarean section electively under spinal anaesthesia were considered for the trial and divided into three groups to receive oxytocin bolus of one, two or three units. The uterine tone was assessed at 2 min after oxytocin administration. Intraoperative blood loss, mean arterial pressure, heart rate and possible side effects were also compared. Paired t-test, Kruskal-Wallis test, Chi-square test and analysis of variance (ANOVA) test with Scheffe multiple comparisons were used as inferential statistics. RESULTS: Adequate uterine contraction was seen in 66% of participants who received one unit of oxytocin, and in 83.3% of participants who received two units of oxytocin. All those who received three units of oxytocin had an adequate uterine contraction. Blood loss was inversely related to the bolus dose of oxytocin. CONCLUSIONS: Lower bolus oxytocin doses of one and two units were inadequate for uterine contraction at elective caeserean section, while three units appeared to be effective in terms of adequate uterine contraction, reduced blood loss and stable haemodynamic system and absent side effects.