B-lines score on lung ultrasound as a direct measure of respiratory dysfunction in ICU patients with acute kidney injury.

PURPOSE: Fluid overload is frequently found in critically ill patients with acute kidney injury (AKI) and is associated with adverse outcomes. Lung ultrasonography (LUS) and bioimpedance spectroscopy (BIS) are potentially useful tools for the noninvasive volume assessment. We evaluated the utility of these measures, alone or in combination, in estimating the PaO2/FiO2 ratio in critical patients with AKI.

METHODS

In a prospective pilot observational study we included 45 patients who presented on admission or developed at any time during intensive care unit stay AKI defined according to KDIGO criteria. Patients were studied at baseline and after 48 h with LUS, BIS and arterial blood gas.

RESULTS

In the univariable analysis, the PaO2/FiO2 ratio was negatively correlated with the B-lines score, and this association was maintained even after adjustments. A cutoff value of 17 for the B-lines score has a sensibility of 76% and a specificity of 65% in identifying patients with PaO2/FiO2 < 300.

CONCLUSION

LUS can be used for functional lung evaluation and identification of patients with increase pulmonary water content and decrease PaO2/FiO2 ratio.