Acute respiratory failure.

There appears to be a great similarity between all of the various types of Adult Respiratory Distress Syndromes (ARDS) in that they are all characterized by progressively increasing interstitial edema in the lungs and a reduced functional residual capacity. Early diagnosis is mandatory and therapy should be started as soon as there is a reasonable suspicion, based on the patient's injury or illness and the previous condition of his lungs, that acute respiratory failure is developing. Sepsis, shock, CNS or thoracic disease and trauma are important associated factors. Blood gas changes usually cannot be appreciated clinically until the respiratory problem is quite severe. Accordingly, serial blood gas analyses should be performed on any patient who has a reasonable chance of developing ARDS. We have found that changes in the estimated AaDO2 on room air are especially helpful. Any deterioration in the patient's clinical condition, blood gases or ventilatory effort should be considered as an indication for early ventilatory assistance. Control of the primary process, careful dehydration, high tidal volumes, and PEEP are the mainstays of therapy. Serial blood gases and careful observation of the patient's effective compliance are essential to determine the optimal ventilator setting and the optimal amount of PEEP. Recently intermittent mandatory ventilation (IMV) with very large amounts of PEEP have been reported to be of value. Early administration of massive steroids should be considered if the patient fails to respond promptly to correction of the underlying etiologic problem, particularly sepsis, careful progressive dehydration and optimal expansion of the alveoli, with high tidal volumes and PEEP.