These patients have a high mortality: 53 percent (27 of 51) for those with myocardial infarction alone, 80 percent (24 of 30) for myocardial infarction and systolic blood pressure of 130 mm Hg or less, and 91 percent (10 of 11) for the subset taking calcium channel blockers with myocardial infarction and systolic blood pressure of 130 mm Hg or less. Persistent hemodynamic insufficiency at 24 hours also carried a poor prognosis; 68 percent (21 of 31) of patients requiring treatment with vasopressors at that time died. In patients with hemodynamic instability, mechanical ventilation may help spare myocardium, but the ultimate outcome remains dependent on the reversible myocardial loss.
The other group consists of patients with chronic left ventricular dysfunction who do not have irreversible ischemic heart injury and who require intubation primarily for hypercarbic respiratory failure. Mechanical ventilation benefits this group by supporting the respiratory system until the work of breathing is reduced by definitive treatment of pulmonary edema. The prognosis in this group is good; the mortality rate was only 3.5 percent (1 of 28) among patients with PaC02 greater than 45, no myocardial infarction, and blood pressure greater than 130 mm Hg.
This study offers a means to distinguish these groups and estimate mortality in patients with cardiogenic pulmonary edema and respiratory failure. This distinction will be important in the evaluation of therapeutic regimens and analysis of outcome for cardiogenic pulmonary edema. Identifying patients with a high probability of mortality could also aid clinicians in determining the vigor with which intensive, invasive care is continued.