[Choice of optimal respiratory support in acute parenchymatous respiratory failure].

The principal goals of respiratory therapy for acute respiratory failure are to correct gas exchange and to lower respiratory performance. In acute lung lesion syndrome (ALLS) and acute respiratory distress syndrome (ARDS), the oxygenation index (PaO2/FiO2) reflects the degree of alveolar-capillary membrane damage. The changes in PaO2/FiO2 between 400 to 300 at adequate ventilation can be interpreted as occult alveolar-capillary insufficiency. The principle of power saving in ALLS/ARDS is to choose a respiratory support regimen that may ensure oxygenation safety by eliminating the excess work of respiration. The ratio of PaO2/FiO2/VO2 is proposed to consider to be a criterion for the effectiveness of respiratory support in ALLS/ARDS and a marker of energy deficiency. It has been established that the function of the alveolar-capillary membrane is not impaired with the PaO2/FiO2 ratio of more than 1.5 and the ratio of less than 1.0 is typical of the severe course of the severe course of ARDS and suggests both alveolar-capillary membrane damage and energy deficiency.