The primary endpoint was the percentage of patients meeting criteria for ETI , including either one or more major criteria ( respiratory arrest , respiratory pauses with unconsciousness , severe hemodynamic instability , intolerance ) or at least two minor criteria ( reduction of at least 30 % of basal PaO2/FiO2 ratio , increase of 20 % of PaCO2 , worsening of alertness , respiratory distress , SpO2 less than 90 % , exhaustion ) .