Ultrasound Guided Fluid Loading Before Spinal Anesthesia

Overview

Perioperative hypotension is a common complication of spinal anesthesia during cesarean sections. The aim of this study was to evaluate the effectiveness of echoguided correction of hypovolemia through crystalloid preloading on the incidence of arterial hypotension during scheduled cesarean sections under spinal anesthesia. It was a double-blind, randomized controlled trial study conducted on hypovolemic parturients, scheduled for cesarean section. investigators compared ultrasound guided correction of hypovolemia to a standard care protocol without preloading. Hypovolemia was defined as a ≥12% increase in the variation of the velocity-time integral of subaortic blood flow during a passive leg raising test. Preloading was guided by the variation of the velocity-time integral of subaortic blood flow during volume expansion tests.

In the literature, numerous studies have compared the different pre-filling and co-filling protocols with different solutes. The majority of them conclude that co-filling is superior to pre-filling when the same type of solute is used. Pre-filling with crystalloids was then abandoned in favor of co-filling with crystalloids It is essential to remember that several invasive or non-invasive means of hemodynamic monitoring have previously been validated in pregnant women The use of invasive tools for assessing blood volume, particularly arterial and central venous catheters, is limited given the brevity of obstetric procedures, the risk of morbidity in awake patients and their high costs. Although non-invasive methods are preferable, some remain imperfect, notably carotid Doppler and bioimpedance devices Transthoracic echocardiography stands out as a particularly reliable and relevant non-invasive tool for assessing cardiac output and blood volume in parturients It allows analysis of the variation of the subaortic velocity time integral (∆ ITV s-a) during the passive leg raise test (LET). It is the only dynamic preload parameter validated in patients during spontaneous ventilation, thus allowing assessment of blood volume. After reviewing the literature, the investigators found no studies about, exclusively hypovolemic patients, the effect of combining pre-filling with co-filling with crystalloids, monitored by echocardiographic preload-dependence indices, on the incidence of arterial hypotension during elective cesarean sections performed under spinal anesthesia. In this study, monitoring was performed by transthoracic echocardiography, based on the variation in subaortic TVI following the passive leg raise test and vascular fluid tests. The objective of this prospective randomized study was to evaluate the efficacy of ultrasound-guided correction of hypovolemia by pre-filling with crystalloids on the incidence of arterial hypotension during elective cesarean sections performed under spinal anesthesia.