MANAGEMENT OF POST-SPINAL HYPOTENSION IN C SECTION - A RETROSPECTIVE COMPARISON BETWEEN EPHEDRINE AND MEPHENTERMINE

Abstract

INTRODUCTION

Obstetric anesthesia practice has adapted to a better understanding of maternal-fetal conditions, risks, and benefits. Caesarean deliveries have become one of the most commonly performed surgical procedures. Most often, neuraxial techniques are the anesthetic of choice.^[1] Spinal, Epidural, Combined Spinal Epidural (CSE), Epidural volume extension, and sequential are all neuraxial blockades described. Spinal anesthesia provides rapid onset, dense blockade with a definite endpoint. Hence spinal anesthesia is the most preferred technique. Due to the profound sympathetic down, hypotension is the most common side effect; this may be exaggerated by the aortocaval compression by the gravid uterus. Hypotension is clinically significant as it may lead to fetal acidosis due to diminished uteroplacental flow. Strategies to manage hypotension include positioning, fluids, and vasopressors. In this study, we intend to compare two vasopressors in identical dosage which may overcome the unpleasant pharmacological effects of one over the other. The vasopressors which are commonly used are being retrospectively analyzed for their pharmacological and clinical effects.

AIMS AND OBJECTIVES

• To compare the efficacy of ephedrine and mephentermine in post-spinal hypotension in C sections.


• To evaluate the recommendation of the right vasopressor in mothers with comorbidities.

MATERIALS AND METHODS

Study Type: Retrospective / as recommended by obstetricians

Study Population: All C sections under ASA 2 & 1

Study Period: October 24 - December 2024

Sample Size 50

Exclusion Criteria: ASA II & IV

• All patients were shifted in the left lateral position to the operation theatre and coloaded with one liter of Ringer’s lactate solution.


• Lumbar subarachnoid block with 2 ml of 0.5% bupivacaine heavy was administered at L3-L4 by 25 G Quincke’s needle.


• Pulse rate, systolic, diastolic, and mean arterial blood pressure were noted every 3 minutes until 15 minutes after spinal anesthesia along with preoperative values.


• The first group of 25 patients received 6 mg of inj. ephedrine and the second group of 25 patients received 6 mg of inj. Mephentermine when systolic blood pressure drops below 90 mmHg. The drug was given intravenously and response was noted every 3 minutes. The need for incremental doses, the presence of tachycardia, sustenance of uterine contraction, and any hypotensive response were noted. The results were tabulated and analyzed.

RESULTS

In general, the systolic blood pressure drops at the 3rd minute and may fall again at the 9th or 12th minute depending on obstetric reasons (Big baby / difficult extraction). There is also a concomitant mild fall in pulse rate. In Ephedrine group, the first fall in SBP at the 3rd minute to 90 mm Hg had the first increment. Mean heart rate increased to 107 and maintained above a mean of 96 per minute. 16 out of 25 patients needed a repeat dose of ephedrine (6 mg), and 3 patients needed 2 repeat doses. In Mephenteramine group, the first fall in SBP at the 3rd minute had the first increment of 6 mg intravenously. The mean heart rate was 86 per minute, which maintained at a mean of 90 per minute. There was no need for an incremental dose, and no abnormal rise in diastolic blood pressure was noted. The indications for C-sections and distribution were nearly identical in both groups.

CONCLUSION

Post-spinal hypotension is a side effect of the lumbar subarachnoid blockade, which could occur in spite of adequate fluids and left lateral tilt. Appropriate vasopressors are needed and must be judiciously used by individual patient parameter trends. Ephedrine is an alpha, beta one, and beta two agonist and enjoys privilege though tachyphylaxis and tachycardia are well documented. Alternative vasopressors are needed where these effects are undesirable. Though an alpha agonist, the property of potentiating endogenous noradrenaline by mephentermine is beneficial. In comparable doses of 6 mg could be considered. Being molecularly associated with methamphetamine, mephentermine is not widely available and offers limitations to its usage.