Likewise , the association between VD/VT and mortality was significant on study day 1 ( odds ratio per 0.10 change in V ( D ) / V ( T ) [ 95 % CI ] : 6.84 [ 1.62-28 .84 ] P = .01 ; and study day 2 : 4.90 [ 1.28-18 .73 ] P = .02 ) after adjusting for V ( D ) / V ( T ) , P ( aO2 ) / F ( IO2 ) , oxygenation index , vasopressor use , and the primary risk for ARDS .