Acute respiratory distress syndrome related to influenza A H1N1 infection: correlation of pulmonary computed tomography findings to extracorporeal membrane oxygenation treatment and clinical outcome.

PURPOSE

The aim of the present study was to correlate computed tomography appearances with clinical severity and outcome using a total lung disease (TLD) score in patients with acute respiratory distress syndrome (ARDS) related to influenza A H1N1 infection.

MATERIALS AND METHODS

Chest computed tomographic scans of 33 patients admitted in the intensive care unit with ARDS related to influenza A H1N1 were retrospectively reviewed. Total lung disease was calculated from the combined extent of consolidation (TLC) and ground glass (TLGG) in the anterior, middle, and posterior segments of the lungs at 3 different levels (apex, hila, and base) using the method described by Goodman et al (Radiology. 213:545-552;1999). Total lung disease, TLC, and TLGG were statistically correlated with demographic characteristics, requirement for extracorporeal membrane oxygenation (ECMO) treatment, and patient outcome.

RESULTS

Total lung disease is higher in patients who require ECMO treatment (P = .016). It is significantly higher (P = .003) in the posterior segments and significantly lower (P = .0001) in the anterior segments compared with TLGG. Total consolidation significantly increases (P = .0001), whereas TLGG significantly decreases (P = .0001) from the anterior toward the posterior segments. There is also a significant increase in TLD (P = .0001), TLC (P = .0001), and TLGG (P = .004) from the apices to the lung bases. There is a negative correlation between TLD and age (P = .01), and TLGG and body mass index (P = .014). Total consolidation is higher (P = .013) and TLGG is lower (P = .012) in patients with a body mass index greater than 30 kg/m(2).

CONCLUSION

A greater extent of air-space disease in ARDS related to influenza A H1N1 infection is associated with progression to ECMO treatment and, therefore, clinical severity. The extent of total air-space disease is greater in younger patients, and obesity is related to a more extensive consolidation.