Lung real time three-dimensional imaging in critically ill ventilated patients: a global diagnosis concordance study.

Lung ultrasound (LUS) increases clinical diagnosis performance in intensive care unit (ICU). Real-time three-dimensional (3-D) imaging was compared with two-dimensional (2-D) LUS by assessing the global diagnosis concordance. In this single center, prospective, observational, pilot study, one trained operator performed a 3-D LUS immediately after a 2-D LUS in eight areas of interest on the same areas in 16 ventilated critically ill patients. All cine loops were recorded on a computer without visible link between 2-D and 3-D exams. Two experts blindly reviewed cine loops. Four main diagnoses were proposed: normal lung, consolidation, pleural effusion and interstitial syndrome. Fleiss κ and Cohen's κ values were calculated. In 252 LUS cine loops, the concordance between 2-D and 3-D exams was 83.3% (105/126), 77.6% (99/126) and 80.2% (101/126) for the trained operator and the experts respectively. The Cohen's κ coefficient value was 0.69 [95% Confidence Interval (CI) 0.58-0.80] for expert 1 meaning a substantial agreement. The inter-rater reliability was very good (Fleiss' κ value = 0.94 [95% CI 0.87-1.0]) for 3-D exams. The Cohen's κ was excellent for pleural effusion (κ= 0.93 [95% CI 0.76-1.0]), substantial for normal lung diagnosis (κ = 0.68 [95% CI 0.51-0.86]) and interstitial syndrome (κ = 0.62 [95% CI 0.45-0.80]) and fair for consolidation diagnoses (κ = 0.47 [95% CI 0.30-0.64]). In ICU ventilated patients, there was a substantial concordance between 2-D and 3-D LUS with a good inter-rater reliability. However, the diagnosis concordance for lung consolidation is poor.