Bedside Lung Ultrasound for Postoperative Lung Conditions in Cardiothoracic Intensive Care Unit: Diagnostic Value and Comparison with Bedside Chest Roentgenogram

BACKGROUND: The postoperative settings in cardiothoracic intensive care unit (ICU) patients pose a certain risk with pulmonary dysfunction causing morbidity and mortality. Lung ultrasound (LUS) has a potential to supplant or replace Chest X-rays (CXR) in these subset of patients, who will require bed side pulmonary pathology diagnosis and interventions. AIMS AND OBJECTIVES: Aim of the study is to compare the diagnosis predicted from LUS to the diagnosis made from routine bedside CXR and to find the degree of agreement in diagnosis made by both modalities in different cardiopulmonary pathologies in ICUs. MATERIALS AND METHODS: Prospective observational study involving 250 postoperative patients, admitted in cardio-thoracic and vascular ICU of a tertiary referral centre. LUS was done in the study patients after the scheduled CXR in the immediate postoperative period and postoperative day one. Findings of pulmonary pathologies by each imaging modality were independently interpreted by two different team of specialist investigators. The findings were evaluated for the degree of agreement between the two imaging modalities using Cohen's kappa statistical test. RESULTS: CXR and LUS imaging showed substantial agreement in the diagnosing cardiopulmonary pathologies (κ = 0.652) in the immediate postoperative period as well as on the postoperative day one (κ = 0.740). For specific cardiopulmonary pathologies, the degree of agreement was moderate for pleural effusion (κ = 0.561), substantial for atelectasis (κ = 0.673) and interstitial edema (κ = 0.707) and perfect for pneumothorax (κ = 0.931). CONCLUSIONS: LUS can effectively replace CXR with reduction in radiation exposure in the immediate postoperative period and also in the follow up period. It can be used as a bedside diagnostic and monitoring tool in postoperative cardiothoracic and ICUs for diagnosing pneumothorax, pleural effusion, atelectasis and interstitial edema.