Modified passive leg-raising maneuver to predict fluid responsiveness by transthoracic ultrasound guidance in healthy pigs under sevoflurane anesthesia.

Abstract

This study aimed to evaluate whether the velocity-time integral of aortic blood flow (VTI_Ao) assessed by transthoracic echocardiography is significantly increased after passive leg-raising maneuver (PLRM) in anesthetized and mechanically ventilated fluid responder pigs. Eight healthy Landrace pigs were anesthetized, mechanically ventilated, and subjected to PLRM. Ultrasound-guided VTI_Ao measurements were taken before and after PLRM and compared to assess changes. Fluid challenge was then performed, and changes in VTI_Ao were assessed to classify pigs as fluid responders or non-responders. Following PLRM, fluid responders exhibited a significant increase in VTI_Ao compared to baseline (p = 0.017). An optimal cutoff of 11.2% for ΔVTI_Ao was calculated for predicting fluid responsiveness after PLRM, with an AUROC of 1.00 (95% CI not estimated – 1.00), sensitivity of 100% (95% CI 59 – 100%), specificity of 100% (95% CI 2.5–100%), positive predictive value of 100% (95% CI 59–100%), and a negative predictive value of 100% (95% CI 2.5–100%). This study demonstrates the potential of using ultrasound-guided VTI_Ao measurements associated with PLRM to predict fluid responsiveness in anesthetized pigs. A ΔVTI_Ao value of ≥11.2% reliably identified fluid-responsive pigs under anesthesia and mechanical ventilation, offering a non-invasive alternative to fluid challenges. Further research addressing study limitations could enhance understanding of fluid responsiveness assessment in animal models.