Modelo de probabilidad de ventilación mecánica prolongada

objective: to design a probability model for prolonged mechanical ventilation (pmv) using variables obtained during the first 24hours of the start of mv. design: an observational, prospective, multicenter cohort study. scope: thirteen spanish medical-surgical intensive care units. patients: adult patients requiring mechanical ventilation for more than 24hours. interventions: none. study variables: apache ii, sofa, demographic data, clinical data, reason for mechanical ventilation, comorbidity, and functional condition. a multivariate risk model was constructed. the model contemplated a dependent variable with three possible conditions: 1. early mortality; 2. early extubation; and 3. pmv. results: of the 1661 included patients, 67.9% (n=1127) were men. age: 62.1±16.2 years. apache ii: 20.3±7.5. total sofa: 8.4±3.5. the apache ii and sofa scores were higher in patients ventilated for 7 or more days (p=0.04 and p=0.0001, respectively). noninvasive ventilation failure was related to pmv (p=0.005). a multivariate model for the three above exposed outcomes was generated. the overall accuracy of the model in the training and validation sample was 0.763 (95%ic: 0.729-0.804) and 0.751 (95%ic: 0.672-0.816), respectively. the likelihood ratios (lrs) for early extubation, involving a cutoff point of 0.65, in the training sample were lr (+): 2.37 (95%ci: 1.77-3.19) and lr (-): 0.47 (95%ci: 0.41-0.55). the lrs for the early mortality model, for a cutoff point of 0.73, in the training sample, were lr (+): 2.64 (95%ci: 2.01-3.4) and lr (-): 0.39 (95%ci: 0.30-0.51). conclusions: the proposed model could be a helpful tool in decision making. however, because of its moderate accuracy, it should be considered as a first approach, and the results should be corroborated by further studies involving larger samples and the use of standardized criteria.