Risk factors for intubation as a guide for noninvasive ventilation in patients with severe acute cardiogenic pulmonary edema

Objective. Noninvasive ventilation may reduce the endotracheal intubation rate in patients with acute cardiogenic pulmonary edema. However, criteria for selecting candidates for this technique are not well established. We analyzed a cohort of patients with severe acute cardiogenic pulmonary edema managed by conventional therapy to identify risk factors for intubation. These factors were used as guide for indications for noninvasive ventilation. Design and setting. Observational cohort registry in the ICU and emergency and cardiology departments in a community teaching hospital. Patients. 110 consecutive patients with acute cardiogenic pulmonary edema, 80 of whom received conventional oxygen therapy.<LF>Interventions. Physiological measurements and blood gas samples registered upon admission. Measurements and results. Twenty-one patients (26%) treated with conventional oxygen therapy needed intubation. Acute myocardial infarction, pH below 7.25, low ejection fraction (<30%), hypercapnia, and systolic blood pressure below 140 mmHg were independent predictors for intubation. Conversely, systolic blood pressure of 180 mmHg or higher showed to be a protective factor since only two patients with this blood pressure value required intubation (8%)], both presenting with a pH lower than 7.25. Considering systolic blood pressure lower than 180 mmHg, patients who showed hypercapnia presented a high intubation rate (13/21, 62%) whereas the rate of intubation in patients with normocapnia was intermediate (6/23, 26%). All normocapnic patients with pH less than 7.25 required intubation. No patient with hypocapnia was intubated regardless the level of blood pressure. Conclusions. Patients with pH less than 7.25 or systolic blood pressure less than 180 mmHg associated with hypercapnia should be promptly considered for noninvasive ventilation. With this strategy about 40% of the patients would be initially treated with this technique, which would involve nearly 90% of the patients that require intubation.