Table 1

Relationship between the interval since high flow oxygen was received and prevalence of acidosis and hypoxia in the admission arterial blood gas

% with pH<7.35 on admission% with PaO2≤8.0 on admission
% (N)% (N)
Proportion of cases with:
High flow oxygen not received before arterial gases taken14 (403/2942)38 (1143/2983)
Time interval between high flow oxygen stopped and blood gases taken:
 >60 min before gases20 (107/537)39 (211/538)
 >15 but ≤60 min before gases36 (127/350)34 (120/352)
 ≤15 min before gases52 (44/85)33 (28/85)
χ2 p value (comparing above three groups)p<0.001p=0.22
Still receiving high flow oxygen when gases taken52 (244/471)11 (53/479)