Response of NICOM stroke volume to passive leg raising to predict fluid responsiveness in critically ill patients with spontaneous breathing activity

Introduction

Volume responsiveness cannot be predicted by the respiratory variation in arterial pressure in hemodynamically unstable patients with spontaneous breathing activity. The NICOM device (Reliant^®; Cheetah) (bioreactance technique) is a totally non-invasive hemodynamic monitoring technique for the measurement of stroke volume. Our objective was to test whether volume responsiveness could be predicted by the response of stroke volume measured by the NCOM device to passive leg raising (PLR) in patients with spontaneous breathing activity.

Methods

Prospective study in the respiratory critical care of a university hospital. Eleven patients with spontaneously breathing activity considered for volume expansion. An increase in stroke volume index (SVi) of 15% or more after volume expansion defined a responder patient. We measured the response of the bioreactance stroke volume to PLR and to saline infusion (500 ml over 15 minutes).

Results

The proportional changes in NiCOM-SVi induced by PLR were correlated with the proportional changes in NICOM-SVi induced by volume expansion (r = 0.67, P = 0.02). The proportional changes in NICOM-cardiac index (CI) induced by PLR were also correlated with the proportional changes in NICOM-CI induced by volume expansion (r = 0.63, P = 0.03). A PLR-induced increase in stroke volume of 9% or more predicted an increase in stroke volume of 15% or more after volume expansion with a sensitivity of 100% and a specificity of 80%.

Conclusions

The response of NICOM-stroke volume to PLR was a good predictor of volume responsiveness. In our hemodynamically unstable patients with spontaneous breathing activity, fluid responsiveness can be assessed totally non-invasively with a bioreactance device.