Fluid responsiveness predicted by noninvasive bioreactance-based passive leg raise test

Area of Science:

• Critical Care Medicine
• Cardiovascular Physiology
• Medical Device Technology

Background:

• Fluid responsiveness (FR) assessment is crucial for hemodynamic management in intensive care unit (ICU) patients.
• Noninvasive monitoring of cardiac output (CO) is desirable to guide fluid therapy.
• Passive leg raising (PLR) is a maneuver that can transiently increase venous return and cardiac output.

Purpose of the Study:

• To evaluate the feasibility of predicting fluid responsiveness (FR) using passive leg raising (PLR).
• To assess the utility of a Bioreactance-based noninvasive cardiac output monitoring device (NICOM) for this prediction.
• To determine the accuracy of PLR-induced changes in CO for predicting FR in post-cardiac surgery patients.

Main Methods:

• A prospective, two-center study involving 75 adult ICU patients post-cardiac surgery.
• Continuous CO monitoring using NICOM at baseline, during PLR, and after fluid infusion.
• Analysis of CO changes with varying thresholds for PLR and FR prediction, including the least minimum significant change (LMSC).

Main Results:

• The least minimum significant change (LMSC) for CO was determined to be 8.85%.
• PLR-induced changes in CO strongly correlated with changes after fluid bolus (r = 0.77).
• Using PLR ≥ 0% to predict FR ≥ 0% yielded 88% sensitivity and 100% specificity; PLR > 9% predicting FR > 9% yielded 68% sensitivity and 95% specificity.

Conclusions:

• The Bioreactance-based NICOM system is clinically valid for predicting fluid responsiveness in this patient population.
• Changes in CO during PLR can reliably predict FR in post-cardiac surgery ICU patients.
• Noninvasive CO monitoring with PLR offers a promising approach for hemodynamic management.