Introduction: Prognostic factors are used in the Intensive Care Unit (ICU) to predict morbidity and mortality, especially in patients on mechanical ventilation (MV). Training protocols are used in MV patients with the aim of promoting the success of the weaning process. Objective: To assess which variables determine the outcome of patients undergoing mechanical ventilation and compare the effects of two protocols for weaning. Method: Patients under MV for more than 48 hours had collected the following information: gender, age, ideal weight, height, Acute Physiology and Chronic Health Evaluation (APACHE II), risk of mortality, Glasgow Coma Scale (GCS) and index Quick and perfunctory (IRRS) breathing. Patients with unsuccessful weaning performed one of weaning protocols: Progressive T -tube or tube -T + Threshold ® IMT. Patients were compared for outcome (death or non-death in the ICU) and the protocols through the t test or Mann-Whitney test was considered significant when P <0.05. Results: Of 128 patients evaluated 56.25% were men, the mean age was 60.05 ± 17.85 years and 40.62% patients died, and they had higher APACHE II scores, mortality risk, time VM and IRRS GCS and the lower value (p<0.05). The age, initial and final maximal inspiratory pressure, time of weaning and duration of MV was similar between protocols. Conclusion: The study suggests that the GCS, APACHE II risk of mortality, length of MV and IRRS variables determined the evolution of MV patients in this sample. Not found differences in the variables studied when comparing the two methods of weaning. Keywords: Intensive Care Unit; Mortality; Ventilator weaning; Respiration, artificial; APACHE; Airway extubation. ResumoIntrodução: Fatores prognósticos são usados na Unidade de Terapia Intensiva (UTI) para predizer morbimortalidade, especialmente em pacientes em Ventilação Mecânica (VM). Protocolos de treinamento são utilizados em pacientes em VM com o intuito de promover o sucesso no processo de desmame ventilatório. Objetivo: Avaliar quais variáveis determinam a evolução de pacientes submetidos à ventilação mecânica e comparar os efeitos de dois protocolos de desmame ventilatório. Método: Pacientes em VM por mais de 48h tiveram as seguintes informações coletadas: sexo, idade, massa ideal, estatura, Acute Physiology and Chronic Health Evaluation (APACHE II), risco de mortalidade, Escala de Coma de Glasgow (ECGl) e Índice de Respiração Rápida e Superficial (IRRS). Pacientes com insucesso de desmame realizaram um dos protocolos de desmame: Tubo-T progressivo ou Tubo-T + Threshold ® IMT. Os pacientes foram comparados quanto ao desfecho (óbito ou não-óbito na UTI) e quanto aos protocolos por meio do Teste t ou Teste Mann-Whitney, foi considerado como significante p<0.05. Resultados: Dos 128 pacientes avaliados 56,25% eram homens, a idade média era 60,05±17,85 anos e 40,62% pacientes foram a óbito, sendo que estes apresentaram maiores valores de APACHE II, risco de mortalidade, tempo de VM e IRRS e menor valor de ECGl (p<0,05). A idade, pressão in...