[Prolonged mechanical ventilation probability model]. / Modelo de probabilidad de ventilación mecánica prolongada.

ABSTRACT

OBJECTIVE: To design a probability model for prolonged mechanical ventilation (PMV) using variables obtained during the first 24 hours 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 24 hours. 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.