Studies on pulmonary function in patients during respiratory treatment. Diagnostic and prognostic evaluations.

Twenty-nine patients, divided into three groups: 1) chronic obstructive pulmonary disease; 2) acute or chronic pulmonary disease with left heart failure; 3) respiratory insufficiency after peritonitis, pancreatitis, and/or sepsis, were studied during respirator treatment with regard to gas exchange, breathing mechanics and central circulation. The dead space ventilation was somewhat greater in group 1 than in the other groups. The alveolar-arterial oxygen tension difference was least in group 1, greater in group 2 and extremely high in group 3. Neither dynamic compliance of the thorax nor inspiratory resistance showed any significant differences between the groups. The cardiac output had the highest values in group 3. The venous admixture was generally small in group 1 and extremely large in group 3. The pulmonary artery pressures were highest in group 2. Three variables proved to be valuable when assessing the prognosis of a patient: a large venous admixture; a large alveolar-arterial oxygen tension difference, and a high pulmonary artery pressure indicated a less favourable prognosis.