ABSTRACT
The pulmonary capillary exchanges oxygen for carbon dioxide across a thin, gas-perme able membrane in a process fundamental to sustaining aerobic metabolism and pH homeo stasis. Because different physiological processes determine the adequacy of tissue oxygen ation and C 0 2 elimination, one of these functions usually takes primacy when the system begins to fail, even though dysfunctional elements of both are often present simulta neously. Episodes of respiratory failure, therefore, may be logically subclassified as oxy genation failure or ventilation failure. This discussion examines both primary manifesta tions of acute respiratory insufficiency with the aim of describing an approach to management that flows from an understanding of the underlying pathophysiology.
