pulmonary (17 vs. 7, p=0.0007) and cardiac (16 vs. 8, p=0.005) disease. On hospital presentation, the two groups had similar rates of hypotension requiring vasopressor therapy, respiratory failure requiring positive pressure ventilation, and acute kidney injury. SOFA scores were similar. Mechanical ventilation (MV) was initiated in most patients in both groups (27 vs. 21, p=1.00). The PaO2/FiO2 ratio was significantly higher in Group A on days 1 (216 vs. 81, p=0.0009), 3 (202 ± 99 vs. 100 ± 46, p=0.002) and 7 (199 ± 103 vs. 113 ± 44, p=0.019) but by day 14 no difference was seen. Tidal volumes were similar throughout, but patients in group B were kept on higher positive end expiratory pressures after day 7 (17 ± 8 vs. 12 ± 6, p=0.035). Rescue therapies were used more often in patients in Group B (48% vs. 20%, p=0.028), including prone ventilation (10 vs. 3, p=0.015), inhaled vasodilator therapy (11 vs. 4, p=0.015) and extracorporeal membrane oxygenation (ECMO) (4 vs. 2, p=NS). Duration of MV, ICU and hospital length of stay and mortality (9 [33%] and 12 [34%]) for both groups were similar. Conclusions: Group B was older, had more underlying diseases, worse oxygenation and utililized rescue modalities more often. The emergence of data supporting treatment modalities (such as ECMO and proning) may have improved outcomes for the patients in Group B.