Background and aims Oxytocin is the uterotonic of choice during caesarean section (CS). However, it may be associated with adverse haemodynamic effects e.g. tachycardia, hypotension, and ECG changes. Even low doses between 0.5 and 3 IU have been shown to produce hypotension in 20–30% cases. Phenylephrine is the vasopressor of choice for management of post-spinal hypotension; the most commonly used bolus dose being 100 µg. It increases blood pressure with associated reflex decrease in heart rate. Thus, phenylephrine might prove beneficial for prevention of oxytocin-induced hypotension and tachycardia.
As earlier literature has shown phenylephrine 50 µg to be ineffective and 80 µg partially effective in abolishing oxytocin induced haemodynamic effects, the present study evaluated efficacy of phenylephrine 100 μg to prevent haemodynamic responses of 3IU oxytocin.
Methods After ethics committee approval, 66 healthy term parturients with uncomplicated, singleton pregnancy undergoing elective CS under spinal anaesthesia received either intravenous phenylephrine 100 μg or normal saline before oxytocin 3IU administered over 30 sec.
Results There was significant fall in mean and diastolic blood pressures within initial 3 min after oxytocin administration in normal saline group (p=0.000), with no significant changes within phenylephrine group. On inter-group analysis, this difference could not achieve statistical significance. However, peak change in systolic pressure was significantly higher in normal saline than in phenylephrine group (table). Heart rate did not change significantly between or within groups (p=0.333). No significant complications occurred in any group.
Conclusions Phenylephrine 100 µg administered before oxytocin maintained haemodynamic parameters better than normal saline during elective CS under spinal anaesthesia.
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