Can blood gas analysis indicate when mechanical ventilation should start in patients with acute myocardial...

Arterial blood gas analysis of 69 patients with acute myocardial infarction were evaluated to provide a basis for respiratory care. Patients were divided into two groups: group A which received oxygen therapy only (n = 38) and group B which received oxygen therapy with mechanical ventilation (n = 31). The patients in group B were further divided into surviving cases (n = 14) and fatal cases (n = 17). On admission patients assigned to group B had lower PaO2 values than those placed in group A. In group B, there was no difference in the P/F value before mechanical ventilation of the surviving and the fatal cases, but the survivors demonstrated an improvement of the P/F value and an increase in cardiac index after mechanical ventilation. It may be reasonable to assume that a P/F value of less than 250 serves as an indicator for the initiation of mechanical ventilation. An increase in the P/F value after mechanical ventilation seems to be a valuable index to estimate prognosis in respiratory failure.