title: Lung ultrasound imaging in avian influenza A (H7N9) respiratory failure.
abstract: BACKGROUND
  Lung ultrasound has been shown to identify in real-time, various pathologies of the lung such as pneumonia, viral pneumonia, and acute respiratory distress syndrome (ARDS). Lung ultrasound maybe a first-line alternative to chest X-ray and CT scan in critically ill patients with respiratory failure. We describe the use of lung ultrasound imaging and findings in two cases of severe respiratory failure from avian influenza A (H7N9) infection.
  
  
  METHODS
  Serial lung ultrasound images and video from two cases of H7N9 respiratory failure requiring mechanical ventilation and extracorporeal membrane oxygenation in a tertiary care intensive care unit were analyzed for characteristic lung ultrasound findings described previously for respiratory failure and infection. These findings were followed serially, correlated with clinical course and chest X-ray.
  
  
  RESULTS
  IN BOTH PATIENTS, CHARACTERISTIC LUNG ULTRASOUND FINDINGS HAVE BEEN OBSERVED AS PREVIOUSLY DESCRIBED IN VIRAL PULMONARY INFECTIONS: subpleural consolidations associated or not with local pleural effusion. In addition, numerous, confluent, or coalescing B-lines leading to 'white lung' with corresponding pleural line thickening are associated with ARDS. Extension or reduction of lesions observed with ultrasound was also correlated respectively with clinical worsening or improvement. Coexisting consolidated pneumonia with sonographic air bronchograms was noted in one patient who did not survive.
  
  
  CONCLUSIONS
  Clinicians with access to point-of-care ultrasonography may use these findings as an alternative to chest X-ray or CT scan. Lung ultrasound imaging may assist in the efficient allocation of intensive care for patients with respiratory failure from viral pulmonary infections, especially in resource scarce settings or situations such as future respiratory virus outbreaks or pandemics.
authors.affiliation: Adult Intensive Care Unit, Queen Mary Hospital, 102 Pok Fu Lam Road, Hong Kong, SAR, China.
authors.forename: Nga Wing
authors.initials: NW
authors.lastname: Tsai
authors.affiliation: Adult Intensive Care Unit, Queen Mary Hospital, 102 Pok Fu Lam Road, Hong Kong, SAR, China.
authors.forename: Chun Wai
authors.initials: CW
authors.lastname: Ngai
authors.affiliation: Accident and Emergency Department, Ruttonjee Hospital, 266 Queen's Way, Wan Chai, Hong Kong, SAR, China.
authors.forename: Ka Leung
authors.initials: KL
authors.lastname: Mok
authors.affiliation: Department of Emergency Medicine, Division of Emergency Ultrasound, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Tsung
keywords: Critical care medicine; Emergency medicine; H7N9; Influenza A virus; Lung ultrasound; Pandemics; Point-of-care; Respiratory failure; Ultrasonography; Viral pneumonia