Physiological Factors Associated with Peri-intubation Severe Adverse Events and Derivation of an Exploratory Bedside Risk Score; A Cross-sectional Study.

INTRODUCTION: Endotracheal intubation is a life-saving procedure, but it can result in complications such as hypotension, hypoxia, and cardiac arrest. This study aimed to identify physiological factors associated with difficult intubation in emergency departments (ED), in order to derive an exploratory bedside risk score. METHODS: This retrospective cohort study included patients aged ≥15 years who underwent endotracheal intubation in the ED. Pre-intubation physiological variables, procedural characteristics, and peri-intubation severe adverse events (severe hypoxemia, hypotension, and cardiac arrest) were extracted from standardized intubation records and electronic medical records. Independent physiological predictors of peri-intubation severe adverse events were extracted using logistic regression analysis, and an exploratory point-based bedside risk score was derived and internally validated. RESULTS: Among 720 eligible patients, 137 (19.0%) experienced peri-intubation severe adverse events. Five clinically relevant physiological predictors were retained in the exploratory score: suspected sepsis, pre-intubation hypoxemia, low serum bicarbonate level, vasopressor requirement before intubation, and shock index >0.9. The simplified score ranged from 0 to 11 points and showed modest discrimination, with an optimism-corrected C-statistic of 0.686. At a threshold of ≥5 points, the score had limited sensitivity (32.1%) but high specificity (90.1%), with a positive predictive value of 43.1% (95% confidence interval (CI): 33.4--53.3) and a positive likelihood ratio of 3.23 (95% CI: 2.29--4.56). CONCLUSION: The exploratory physiological difficulty score showed modest discrimination for peri-intubation severe adverse events. A threshold of ≥5 points identified a subgroup of patients who may require more preparation and closer monitoring before intubation. However, the score should not replace comprehensive clinical assessment and requires external validation.