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 (VTIAo) 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 VTIAo measurements were taken before and after PLRM and compared to assess changes. Fluid challenge was then performed, and changes in VTIAo were assessed to classify pigs as fluid responders or non-responders. Following PLRM, fluid responders exhibited a significant increase in VTIAo compared to baseline (p = 0.017). An optimal cutoff of 11.2% for ΔVTIAo 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 VTIAo measurements associated with PLRM to predict fluid responsiveness in anesthetized pigs. A ΔVTIAo 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.