Lung ultrasound to detect and monitor pulmonary congestion in patients with acute kidney injury in nephrology wards: a pilot study

INTRODUCTION: Lung congestion and frank pulmonary edema are established complications of acute kidney injury (AKI) and early detection and monitoring of lung congestion may be useful for the clinical management of AKI patients. METHODS: We compared standardized clinical criteria (including lung crackles and peripheral edema grading) and simultaneous chest ultrasound (US) to detect lung congestion in a series of 39 inpatients with AKI. RESULTS: At baseline, twelve patients (31%) were clinically euvolemic and twelve presented clear-cur cardiovascular congestion (31%) by clinical criteria. Fifteen patients (38%) were hypovolemic. The median number of US-B lines in patients with cardiovascular congestion was much higher (50, inter-quartile range 27-99) than in euvolemic (14, IQR 11-37) and hypovolemic patients (7, IQR 3-16, P < 0.001). Remarkably, a substantial proportion of asymptomatic euvolemic (66%) and hypovolemic (46%) patients had lung congestion of moderate to severe degree (> 15 US-B lines) by lung US. Crackles severity and the number of US-B lines over time were inter-related (Spearman's ρ = 0.38, P < 0.01) but the agreement (Cohen k statistics) between the two metrics was unsatisfactory. Forty-eight percent of patients had lung congestion of moderate to severe degree by lung US and this estimate by far exceeded that by clinical criteria (32%). CONCLUSIONS: This pilot study shows that chest US has potential for the detection of lung congestion at a pre-clinical stage in AKI. The results of this pilot study form the basis for a clinical trial testing the usefulness of this technique for guiding lung congestion treatment in patients with AKI.