Table 2

 Univariate analysis (variables compared using the t test)

VariableOverall meanAlive mean (SD)Died mean (SD)p Value
Age (y)4134 (16)43 (18)0.001
Duration in hours in hospital before ventilation6615(35)86(206)0.012
Duration of mechanical ventilation (h)116168(124)95(123)<0.001
Alveolar-arterial (A-a) oxygen gradient391350(156)408(145)0.015
P/F ratio2.93.3(2.0)2.7(4.4)0.33
Fluid balance in litres+4.2+6.3(6.9)+3.4(4.8)0.001
Time before tracheotomy (h) (evaluated for only 62 patients)65110(86)32(55)<0.001