T-test both groups Differences DF T Valor Pr>/t/ pO2 LA-pO2 300 37 2.01 0.0515 pO2 AI-pO2 600 35 -0.87 0.3876 pO2 AI-pO2 900 34 -2.90 0.0065 pO2 AI-pO2 1200 34 -5.88 <0001

Table 3: T-Student for different pO2 values in both groups.