The predictive value of different lung ultrasound protocols for extravascular lung water in septic shock patients

Currently, the role of lung ultrasound (LUS) in the diagnosis and treatment of patients with septic shock is widely recognized. Various LUS protocols and scoring criteria have been proposed, yet a unified LUS protocol for assessing lung water in these patients remains lacking.

Forty‑six septic shock patients underwent LUS with three scanning schemes (4‑region, 8‑region, BLUE) alongside pulse indicated continuous cardiac output (PiCCO) monitoring. Spearman correlation analysis was used to compare the correlation between the three ultrasound scoring schemes, PiCCO and other clinical laboratory indicators. At the same time, the value of three LUS protocols for assessing pulmonary water in septic shock patients was evaluated using receiver operating characteristic (ROC) analysis.

Spearman's correlation analysis showed a significant correlation between extravascular lung water index (EVLWI) and 4-region, 8-region, or the Bedside Lung Ultrasound Examination (BLUE) protocol. More importantly, the BLUE protocol showed a stronger correlation with EVLWI than the 4-region protocol and the 8-region protocol (r=0.634, 0.458, 0.546, p<0.001). The ROC curve analysis showed that ultrasound protocols could predict the early occurrence of pulmonary edema in septic shock patients (EVLWI>7 ml/kg), diagnosis of pulmonary edema (EVLWI>10 ml/kg), and evaluation of pulmonary fluid severity (EVLWI≥15 ml/kg).

Our study found that septic shock patients were prone to pulmonary edema during fluid resuscitation, and ultrasound scoring could help us quantify pulmonary edema. Among the 4-region, 8-region and BLUE protocols, the BLUE protocol shows relatively better overall performance in predicting lung water elevation and evaluating edema severity.