There were no statistically significant differences between the two groups for initial laboratory data, including white blood cell count, platelets, serum creatinine, bilirubin, and creatinine kinase. The number of patients who developed acute renal failure that required dialysis throughout their ICU stay was the same (n = 8) in both groups. SOFA scores on days 1, 3, 7, and 14 of mechanical ventilation indicate that patients in the noninfluenza group had more severe organ failure during their ICU stay (p = 0.017; Table 2 ). Table 3 shows oxygenation index and mechanical ventilation related parameters on days 1, 3, 7, and 14. There was a nonsignificant trend toward worsening hypoxia in the H1N1 group, despite significantly higher PEEP and Pplat on days 1, 3, and 14. Tidal volumes were comparable throughout. Plateau pressures in the H1N1 group were high due to the relative decrease in pulmonary compliance in H1N1-related lung injury. Four patients in both groups were ventilated with airway pressure release ventilation (APRV). More patients in the influenza group required rescue therapies on day 1 of mechanical ventilation (4 vs. 0, respectively, p = 0.108); however, similar numbers of patients in both groups required rescue therapies over the duration of MV (7 and 5 patients, respectively). Rescue therapies in the H1N1 group included inhaled NO (n = 4), ECMO (n = 2), prone ventilation (n = 3), and high-frequency ventilation (n = 1), and in the noninfluenza group only inhaled NO (n = 3) and prone ventilation (n = 2).