An understanding of ventilator management must be predicated on physiologic principles. There is a considerable array of equipment, permitting an almost limitless number of permutations in ventilator therapy, to support patients with respiratory failure. The physician who understands patient-ventilator interactions and their effects on cardiopulmonary function will be best equipped to individualize therapy. We believe that further refinements in supportive equipment probably will not improve outcome significantly. Thus, more emphasis should be placed on elucidating the underlying disease process and its effects on respiratory structure and function.