The treatment of respiratory failure has spawned an empire of intensive-care units, specialized personnel, and sophisticated equipment. Although this growth shows no sign of slowing, some questions have been raised by regulatory agencies, and, more recently, by investigators, as to the impact on patient outcome of this impressive array of hardware.1-3 Perhaps nowhere is this growth more evident than in the exponential increase in ventilator models that has occurred during the past ten years (Figure). From slow and hesitating steps, dating back to biblical times, assisted ventilation began blossoming in the 1930s with negative-pressure ventilators, in response to the respiratory problems of neuromuscular disease. With the waning of these disorders, the therapy for respiratory failure turned to that of obstructive lung disease problems, and, later, to the adult respiratory-distress syndrome. Positive airway pressure and modifications of the pressure waveform (eg, positive end-expiratory pressure [PEEP], intermittent mandatory ventilation [IMV]) were