Utility of chest ultrasonography and pulmonary infection score in early diagnosis of ventilator-associated pneumonia

Abstract

Background Ventilator-associated pneumonia (VAP) remains a morbid and prevalent problem throughout the world. Lung ultrasound (LUS) is increasingly being used at the bedside for assessing alveolar-interstitial syndrome, lung consolidation, pneumothorax, and pleural effusion. Purpose The aim was to focus on the use of bedside LUS alone and in association with the clinical pulmonary infection score (CPIS) in early diagnosis of VAP, to describe the sonographic features, to compare between LUS and portable chest radiography (CXR) in early diagnosis of ventilator-associated pneumonia (VAP), and weather LUS affects the prognostic outcomes of VAP. Patients and methods A total of 40 patients with suspected VAP were enrolled. Portable CXR, LUS, and computed tomography scan (gold standard) were performed. The CPIS was calculated for early and reliable diagnosis of VAP. The prognostic outcomes were highlighted. Results Among forty VAP-suspected cases, 30 (75%) were confirmed using computed tomography (gold standard). LUS imaging of VAP cases diagnosed 28 (70%) with consolidation, 89.3% of them with air bronchogram, and 32.5% of them with pleural effusion. Validity for early VAP diagnosis using portable CXR demonstrated 86.7, 100, 100, 71.4, and 90%; ultrasound 93.3, 100, 100, 83.3, and 95%; whereas CPI score 50, 90, 93.8, 62.5, and 60% regarding sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively. CPIS combined with LUS revealed higher sensitivity (96.7%) and accuracy (97.5%). Low CPIS less than or equal to 6, modes of mechanical ventilation (continuous positive airway pressure and biphasic positive airway pressure), shorter duration of respiratory support, LUS imaging of air bronchogram and simple pleural effusion were significantly associated with improved outcomes of VAP cases. The duration of mechanical ventilation and early detection of air bronchogram by LUS were the independent mortality predictors with odds ratio of 2.4 and 3.11 and 95% CI of 1.56–4.55 and 1.8–17.66, respectively. Conclusion LUS was a reliable tool for early VAP diagnosis at the bedside. Combination approach increases the prognostic and diagnostic accuracy of LUS in VAP.

Keywords

• air bronchogram
• clinical pulmonary infection score
• lung ultrasonography
• ventilator-associated pneumonia