Inferior vena cava ultrasoundversuspassive leg raising test in guiding fluid administration in surgical patients prior to spinal anaesthesia: a post-hoc analysis of the ProCRHYSA randomized trial

Abstract

Background: Spinal anaesthesia is commonly used for many surgical procedures. One of its potential complications is arterial hypotension, which is nowadays prevented by an empirical fluid administration without any hemodynamic status assessment. However, this practice could increase the risk of volume overload in cardiovascular high-risk patients. Two non-invasive tests are performed to identify fluid-responsiveness: the Inferior Vena Cava Ultrasound (IVCUS) and the Passive Leg Raising Test (PLRT). Aim of this post-hoc analysis was to compare these two methods in spontaneous-breathing patients to assess fluid responsiveness before spinal anaesthesia. Primary outcome was to analyze the incidence of arterial hypotension after spinal anaesthesia in elective surgery patients. Secondary endpoints compared the total fluids amount, the vasoactive drugs administered and the time needed to accomplish the whole procedure in both groups. Results: The patients analyzed were 132 in the IVCUS group and 148 in the PLRT group; 39.6% of all patients developed arterial hypotension after spinal anaesthesia, 34.8% in the IVCUS group and 43.9% in the PLRT group (Chi-square 2.39, df = 1, p = 0.77). The mean total fluids amount was 794 ± 592 ml; 925 ± 631 ml for IVCUS group and 678 ± 529 ml for PLRT group (p < 0.001). Patients needed vasoactive drugs to restore normal arterial pressure were 18.2% of total, 15% in the IVCUS group and 20% in the PLRT group (p = 0.136). The mean time required to complete the entire procedure was 52 ± 18 min, 48 ± 10 min in the IVCUS group and 56 ± 13 min in the PLRT group (p < 0.001). Complications or out of protocol treatment were registered in 4.6% patients. Conclusions: Fluid responsiveness assessment in spontaneous breathing patients before spinal anaesthesia could potentially prevent the risk of post-spinal hypotension. In elective surgery, IVCUS could be an accurate method to guide fluid administration in patients undergoing spinal anaesthesia, reducing the incidence of post-spinal hypotension when compared to PLRT. KEYWORDS Fluid therapy; Hypotension; Inferior Vena Cava; Spinal Anaesthesia; Ultrasonography.