PREVENTION OF OXYTOCIN-INDUCED HYPOTENSION IN CAESAREAN SECTION BY PHENYLEPHRINE: EFFECT OF PRELOAD Dr. Anita Chikara
Authors: Chikara Anita 
Published: October 2020

Introduction: One of the leading causes of maternal mortality with uterine atony is Postpartum haemorrhage (PPH) and can be reduced by proper use of uterotonic agents like oxytocin which is most commonly used. Approximately 80% of the patients suffers Spinal-induced hypotension (SIH) for cesarean delivery (CD) and is a frequently encountered problem. Postpartum haemorrhage (PPH) is one of the leading causes of maternal mortality with uterine atony in about 50% cases. There are many approaches to prevent hypotension but no single approach has been shown as the gold standard, and each prophylactic treatment comes with accompanying risks. Crystalloid preload can prevent hypotension has a poor efficacy in preventing hypotension, due to rapid redistribution into the extracellular space. Phenylephrine is a short-acting alpha agonist, can be administered by bolus as well as by infusion to treat oxytocin induced hypotension. Phenylephrine obtunds oxytocin-induced decrease in systemic vascular resistance (SVR) and increase in heart rate and cardiac output

Material and Methods: Patients were randomized to be in the colloid or crystalloid infusion groups.  Normal singleton pregnancy, beyond 36 weeks gestation, between 19and 35 years of age, weight between 50 and 100 kg, and height ranging from 150-180 cm. Pre-anaesthetic evaluation of all the patients was done. Intravenous administration of preload was delivered for 30 min, prior to spinal anaesthesia and when the fluid load was complete, IV patency was maintained at a rate of 5 ml/hour and medications were flushed with LR. Standard monitoring for all patients was done through use of non-invasive blood pressure (NIBP) measurement, electrocardiography, and pulse oximetry. Oxygen (2 l/min) was administered via nasal cannula. The average Systolic BP and accompanying heart rate (HR) of these 3 measurements were recorded as mean baseline values. Patients feeling  about nausea was recorded from start of anaesthesia at every 5 minutes interval. Results: Mean age in lacteted ringer solution group was 25.27±5.11 years while in hydroxyethyl starch group it was 26.19±4.67. Mean Spinal uterine incision time was 15.88±4.27 and 17.18±3.35 in lacteted ringer solution group and hydroxyethyl starch group respectively. Estimated blood loss in ml(mean±SD) was 443±59.44 and 479±61.32 in lacteted ringer solution group and hydroxyethyl starch group respectively. Systolic blood pressure baseline (mean±SD) 126.45±11.33 and 129.12±9.24 in lacteted ringer solution group and hydroxyethyl starch group respectively. Heart rate (mean±SD) was 88.87±9.45 and 88.21±10.55 in lacteted ringer solution group and hydroxyethyl starch group respectively. Significantly less phenylephrine was used in the colloid group (1058 ± 558 mcg) compared to the crystalloid group (1400 ± 513 mcg) (P = 0.0019) . There was no significant difference in the incidence of maternal nausea and vomiting, as well as APGAR scores at 1 and 5 min.

Conclusion: In prevention of SIH and treatment, Phenylephrine with collids are found to be superior than crystelloids because of the sparing effect of phenylephrine associated with preloading colloids.

Keywords: crystelloids, collids, lactated, cesarean delivery