Lung ultrasonography for the diagnosis of 11 patients with acute respiratory distress syndrome due to bird flu H7N9 infection

Background: A novel reassortant avian-origin influenza A (H7N9) virus was found to infect three Chinese residents, the first H7N9 infection in humans in Asia. Chest computed tomography (CT) for acute respiratory distress syndrome (ARDS) diagnosis is not only expensive but also exposes patients to radiation and might cause patients to be at risk of infection during transportation; in addition, chest radiography cannot be used to monitor the lung repeatedly in real time. Therefore, the routine use of bedside lung ultrasonography for critically ill patients with ARDS is especially valuable. Objectives: The aim of this study was to evaluate the application of ultrasound for lung examination in patients with ARDS. Methods: Eleven patients infected with H7N9 avian influenza who developed ARDS were diagnosed by lung ultrasonography. Results: Six patients who had severe ARDS showed a diffuse comet tail sign or a consolidation score >= 7 and a lung ultrasound score >= 20 points. A diffuse comet tail sign or a consolidation score <= 6 and a lung ultrasound score < 25 were observed in four patients. One patient showed a diffuse comet tail sign or consolidation area in four lung areas, with an ultrasound score of 14. Among all 11 patients studied, 6 patients had thoracic puncture and drainage of pleural effusion and 2 patients had pneumothorax puncture drainage. Conclusions: Lung ultrasound could be useful for monitoring ARDS caused by the influenza virus A H7N9 strain in clinical applications.