ABSTRACT
Objective
To evaluate whether the velocity–time integral of aortic blood flow (VTIAo) assessed by transthoracic echocardiography is increased after the passive leg-raising maneuver (PLRM) in anesthetized and mechanically ventilated, fluid-responder pigs.
Design
Prospective laboratory study.
Setting
University teaching hospital.
Animals
Eight healthy Landrace pigs.
Interventions
Pigs were anesthetized, mechanically ventilated, and subjected to the PLRM. Ultrasound-guided VTIAo measurements were compared before and after the PLRM to assess changes. A fluid challenge was then performed, and changes in VTIAo were assessed again to classify pigs as fluid responders or nonresponders.
Measurements and Main Results
Seven of the eight animals were responders, and one was a nonresponder. After the PLRM, fluid responders exhibited an increase in VTIAo compared with baseline (p = 0.017). An optimal cutoff of 11.2% for changes in ultrasound-guided VTIAo was calculated for predicting fluid responsiveness after the PLRM, with an area under the receiver operating characteristic curve of 1.00 (95% confidence interval [CI]: not estimated), 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 negative predictive value of 100% (95% CI: 2.5–100).
Conclusions
Despite limitations, this study demonstrates the potential of using ultrasound-guided VTIAo measurements associated with the PLRM to predict fluid responsiveness in anesthetized pigs. An ultrasound-guided VTIAo cutoff of ≥11.2% could serve as a reference for identifying fluid-responsive pigs under anesthesia and mechanical ventilation, and offer a noninvasive alternative to fluid challenges.
Journal of Veterinary Emergency and Critical Care, EarlyView.Wiley: Journal of Veterinary Emergency and Critical Care: Table of Contents