Utility of lung ultrasound for extravascular lung water volume estimation during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

BACKGROUND AND AIMS: Rising extravascular lung-water index (ELWI) following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS + HIPEC), if not timely intervened, can progress to pulmonary oedema. Transpulmonary thermodilution (TPTDL) is a standard technique to estimate ELWI (T-ELWI score), and track ongoing changes. Lung ultrasound (LUS) is another technique for ELWI (L-ELWI score) estimation. However, reproducibility and reliability of LUS for tracking serial L-ELWI changes during CRS + HIPEC remains to be validated. METHODS: This prospective observational study included 360 L-ELWI and T-ELWI measurements at 12 peri-operative time-points. Cohen's Kappa test was used to assess reproducibility, Inter-rater agreement (between the anaesthetist and radiologist), and agreement between LUS and TPTDL for classifying the severity of pulmonary oedema. Reliability of LUS for 'tracking serial changes' in ELWI over time in individual patients was assessed by determining the repeated measures correlation (z-rrm) between weighted L-ELWI and T-ELWI scores. The ability of both techniques to discriminate pulmonary oedema was compared by analysing the area under ROC curves. RESULTS: Excellent inter-rater agreement for assigned L-ELWI scores was observed (linear weighted κ = 0.95 for both). Both techniques had a good agreement in classifying the severity of pulmonary oedema (linear weighted κ = 0.63, 95% CI 0.51–0.79). T-ELWI and weighted L-ELWI scores correlated strongly (z-rrm = 0.88, 95% CI 0.80–0.92, P < 0.0001). Both techniques had comparable ability to discriminate pulmonary oedema (difference in area under ROC curve = 0.0014, 95%CI –0.0027 to 0.0055, P = 0.5043). CONCLUSION: We found the utility of LUS as a reliable and reproducible technique for ELWI estimation and tracking its changes over time in CRS + HIPEC.