Lung Ultrasound for Early Diagnosis of Ventilator-Associated Pneumonia

Abstract
Background: Lung Ultrasound (LUS) has important role in diagnosis of different lung diseases so it can be used in diagnosis and early detection of Ventilator-Associated Pneu-monia (VAP).
Aim of Study: Our aim is to evaluate the sensitivity and the specificity of lung ultrasound for early diagnosis of ventilator-associated pneumonia compared to chest X-ray.
Patients and Methods: This study was carried out on 100 patients divided into two Groups (A & B), each one included 50 adult male and female patients with suspected VAP. In Group A (LUS), we searched for lung ultrasound findings as subpleural consolidation, lobar consolidation, and dynamic arborescent/linear air bronchogram while in Group B (CXR), we searched for chest X-ray findings as lung infiltrates and air bronchogram. In both groups, Endotracheal Aspirates (EA) was collected for direct gram stain examination (EAgram) and culture (EAquant). LUS findings were analyzed in scores as the clinical-LUS score (Ventilator-associated Pneumonia Lung Ultrasound Score [VPLUS]) which was calculated as follows: ³2 areas with subpleural consolidations, 1 point; ³1 area with dynamic arborescent/linear air bronchogram, 2 points; and purulent EA, 1 point. Positive direct gram stain examination (EAgram) or positive culture (EAquant) which had 2 points were added to VPLUS to be VPLUS EAgram and VPLUS EAquant.
Results: The sensitivity and the specificity of lung ultra-sound findings in Group A (LUS) were higher than chest X-ray findings Group B (CXR) as presence of ultrasound signs in Group A (LUS) (lobar/hemilobar consolidations, dynamic air bronchogram, subpleural consolidations) separate or combined gave us sensitivity 97%, lobar or hemilobar consol-idations had sensitivity 94%, presence of dynamic air bron-chogram or subpleural consolidations gave us sensitivity 94%, VPLUS-EAquant ³3 gave us sensitivity 94%. The best spe-cificity was found also in Group A as (air bronchogram + subpleural consolidations + positive culture or positive gram stain examination) gave us the highest specificity 100%, combination of (dynamic air bronchogram and subpleural consolidations) gave us high specificity 94%, combination of (lobar/hemilobar consolidations, dynamic air bronchogram and subpleural consolidations) gave us also high specificity 94%, (VPLUS-EAquant ³4, VPLUS-EAgram ³4 and VPLUS ³3) had specificity 94%. On the other hand, signs of chest X-ray in Group B had lower sensitivity and specificity com-pared to lung ultrasound in Group A as chest X-ray infiltrates gave us sensitivity 53%, specificity 25%, air bronchogram had sensitivity 33%, specificity 40%, presence of (chest X-ray infiltraes, air bronchogram) separate or combined gave us sensitivity 57%, specificity 25%.
Conclusion: The sensitivity and specificity of lung ultra-sound were higher than chest xray, so lung ultrasound is better than chest X-ray for early diagnosis of VAP.