Subclavian vein ultrasound-guided fluid management to prevent post-spinal anaesthetic hypotension: a randomized controlled trial

Abstract

Abstract Background Hypotension frequently occurs after spinal anaesthesia during caesarean delivery, which is recommended to prevent by fluid loading. We evaluated subclavian vein (SCV) ultrasound (US)-guided volume optimisation in preventing hypotension after spinal anaesthesia during caesarean delivery. Methods This randomised controlled study included 80 consecutive full-term parturients scheduled for caesarean delivery under spinal anaesthesia. Women were randomly divided into the SCVUS group, comprising SCVUS analysis before spinal anaesthesia with SCVUS-guided volume management, and the control group without SCVUS assessment. Before anaesthesia, the SCVUS group received 3 mL/kg crystalloid fluid challenges repeatedly within 3 min with a 1-min interval based on the SCV collapsibility index (SCVCI), while the control group received a fixed dose (10 mL/kg). Incidence of post-spinal anaesthetic hypotension was the primary outcome. Total fluid volume, vasopressor dosage, changes in hemodynamic parameters, maternal adverse effects, and neonatal status were secondary outcomes. Results The total fluid volume was significantly higher in the control group than in the SCVUS group (690 [108] vs. 160 [280] mL, p < 0.001), while the phenylephrine dose (0 [40] vs. 0 [30] µg, p = 0.276) and incidence of post-spinal anaesthetic hypotension (65% vs. 60%, p = 0.950) were comparable. The incidence of maternal adverse effects, including nausea/vomiting and bradycardia (12.5% vs. 17.5%, p = 0.531 and 7.5% vs. 5%, p = 1, respectively), and neonatal outcomes (Apgar scores) were comparable between the groups. SCVCI correlated with the amount of fluid administered (R = 0.885, p < 0.001). Conclusions SCVUS-guided volume management did not ameliorate post-spinal anaesthetic hypotension but reduced the volume of the preload required before spinal anaesthesia. Trail registration: The trial was registered with the Chinese Clinical Trial Registry at chictr.org.cn (registration number, ChiCTR2100055050) on December 31, 2021.