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Background: Although protective mechanical ventilation (MV) has been used in a variety of applications, lung injury may occur in both patients with and without acute respiratory distress syndrome (ARDS). The purpose of this study is to use machine learning to identify clinical phenotypes for critically ill patients with MV in intensive care units (ICUs).Methods: A retrospective cohort study was conducted with 5013 patients who had undergone MV and treatment in the Department of Critical Care Medicine, Peking Union Medical College Hospital. Statistical and machine learning methods were used. All the data used in this study, including demographics, vital signs, circulation parameters and mechanical ventilator parameters, etc., were automatically extracted from the electronic health record (EHR) system. An external database, Medical Information Mart for Intensive Care III (MIMIC III), was used for validation.Results: Phenotypes were derived from a total of 4009 patients who underwent MV using a latent profile analysis of 22 variables. The associations between the phenotypes and disease severity and clinical outcomes were assessed. Another 1004 patients in the database were enrolled for validation. Of the five derived phenotypes, phenotype I was the most common subgroup (n = 2174; 54.2%) and was mostly composed of the postoperative population. Phenotype II (n = 480; 12.0%) led to the most severe conditions. Phenotype III (n = 241; 6.01%) was associated with high positive end-expiratory pressure (PEEP) and low mean airway pressure. Phenotype IV (n = 368; 9.18%) was associated with high driving pressure, and younger patients comprised a large proportion of the phenotype V group (n = 746; 18.6%). In addition, we found that the mortality rate of Phenotype IV was significantly higher than that of the other phenotypes. In this subgroup, the number of patients in the sequential organ failure assessment (SOFA) score segment (9,22] was 198, the number of deaths was 88, and the mortality rate was higher than 44%. However, the cumulative 28-day mortality of Phenotypes IV and II, which were 101 of 368 (27.4%) and 87 of 480 (18.1%) unique patients, respectively, was significantly higher than those of the other phenotypes. There were consistent phenotype distributions and differences in biomarker patterns by phenotype in the validation cohort, and external verification with MIMIC III further generated supportive results.Conclusions: Five clinical phenotypes were correlated with different disease severities and clinical outcomes, which suggested that these phenotypes may help in understanding heterogeneity in MV treatment effects. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to explore the relationship between the variables of mechanical ventilation and circulatory perfusion and its association with ICU mortality during the first day of mechanical ventilation.Design: Retrospective cohort study.Setting: The Department of Critical Care Medicine, Peking Union Medical College Hospital.Patients: Patients who have undergone mechanical ventilation.Interventions: None.Measurements and Main Results: This study used the main clinical data obtained from the real-time bedside messaging systems of mechanically ventilated patients during their first day in the ICU from May 2013 to May 2016, including data on the variables of mechanical ventilation and circulatory perfusion. An analysis was then performed on the association of the above data with the patient's in-ICU mortality. There were 5,103 patients who received mechanical ventilation during this period, and of these, 309 patients died during their ICU treatment. Peak airway pressure, mean airway pressure, respiratory rate, heart rate, mean arterial pressure, FIO2, blood oxygen saturation, PO2, peripheral perfusion index, and lactate level were correlated with patient outcomes. A Cox logistic regression analysis suggested that mean airway pressure and perfusion index were the most independent risk and protective factors, respectively, for patient ICU mortality. The areas under the curve for a poor prognosis for mean airway pressure and perfusion index were 0.799 (95% CI, 0.77-0.829) and 0.759 (95% CI, 0.729-0.789), respectively. Further, mean airway pressure and perfusion index exhibited a causal interaction. The relative excess risk due to interaction was 2.061 (-0.691 to 4.814), the attributable proportion due to interaction was 0.210 (-0.027 to 0.447), and the synergy index was 1.306 (0.930-1.833).Conclusions: A higher mean airway pressure and lower perfusion index provided a worse prognosis in mechanically ventilated patients, and it appears that these two variables have a casual interaction. [ABSTRACT FROM AUTHOR]