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Predictors of mortality and prolonged mechanical ventilation in patients admitted to a medical-surgical intensive care unit


Ventilatory support has become a major therapeutic modality in intensive care units. However, scarce data exist on the clinical characteristics and prognosis of patients managed in private hospitals in Brazil.


The objectives of this study are (1) to describe demographics, clinical features, physiologic parameters, and prognosis of patients on mechanical ventilation admitted to the Intensive Care Unit of Hospital Moinhos de Vento; and (2) to identify predictors of mortality and ventilator time.


All consecutive patients admitted between June and November 2000 in the medical-surgical intensive care unit, who required mechanical ventilation for more than 24 h because of acute respiratory failure, were included in this observational study. Clinical and ventilatory parameters were recorded twice daily, within 8-12 h intervals. Major end-points evaluated were mortality and duration of mechanical ventilation. Multivariate analyses were performed to identify independent predictors of prognosis.


Fifty-nine patients (in 794 screening evaluations) were studied, mean age of 66 ± 18 (20-98) years, 39 (66%) were male, and mean APACHEII score of 20 ± 7. Most frequent causes of acute respiratory failure were nosocomial respiratory infection (14%), community-acquired pneumonia (12%) and acute neurologic injury (24%). Similar proportion of patients had primary respiratory (42%) and nonrespiratory (58%) disorders. In-hospital mortality was 31% (18 patients). In univariate analysis, age, APACHEII score, primary respiratory disorders, inotropic use, heart rate and inspired fraction of oxygen (FiO2) at baseline were associated with increased hospital mortality (Table). Chest radiographic findings at admission, such as pulmonary infiltrates and severity score, were not significantly associated with hospital outcome. However, by multivariate analysis, APACHEII was the only independent predictor of mortality.


Duration of mechanical ventilation was 8 ± 8 days (median 7 days) and length of ICU stay was 14 ± 12 days (median 10 days). Predictors of prolonged mechanical ventilation were low ratio of PaO2/FiO2, high static compliance and inotropic use at baseline. Mortality was higher after 3 days of mechanical ventilation (31% versus 17%), although the difference was not statistically significant.


In this heterogeneous cohort of medical-surgical patients, demographics and clinical features were similar to those described in other studies. Indications for mechanical ventilation showed a pattern resembling other ICUs in Brazil, but were different from other countries. Hospital prognosis and predictors of mortality and prolonged mechanical ventilation does not appear to be different from other institutions. Nevertheless, these results, in conjunction with prior studies, may help planning resource allocation more effectively in the ICU.

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Oliveira, E., Boschi, E., Guths, H. et al. Predictors of mortality and prolonged mechanical ventilation in patients admitted to a medical-surgical intensive care unit. Crit Care 5 (Suppl 3), P93 (2001).

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