Pre-intubation Shock Index as a Predictor of Post-intubation Hypotension in Adult Patients Undergoing Emergency Endotracheal Intubation: A Retrospective Observational Study

Abstract

Introduction: Post-intubation hypotension (PIH) is a common complication of emergency endotracheal intubation and is associated with increased morbidity and mortality. Early identification of high-risk patients may enable timely hemodynamic optimization. The Shock Index (SI), calculated as heart rate divided by systolic blood pressure, is a simple bedside marker of circulatory instability.

Aim & Objective: This study evaluated the incidence, predictors, and clinical impact of PIH, with emphasis on the predictive value of pre-intubation SI.

Materials & Methods: This retrospective observational study included adult patients undergoing emergency endotracheal intubation at a tertiary care emergency department. Of 435 patients screened, 280 met the inclusion criteria. Demographic, clinical, hemodynamic, and outcome data were obtained from the institutional airway registry and medical records. Independent predictors of PIH were identified using multivariable logistic regression, and receiver operating characteristic (ROC) analysis was used to assess the predictive performance of SI.

Results: PIH occurred in 62 patients (22.1%). Patients with PIH were significantly older and had a higher prevalence of chronic obstructive pulmonary disease, chronic renal insufficiency, and diabetes mellitus. They also had higher pre-intubation heart rate, lower systolic blood pressure, and higher SI. PIH was associated with increased vasopressor use, post-intubation cardiac arrest, and in-hospital mortality. Pre-intubation SI was the strongest independent predictor of PIH (adjusted OR 48.6, 95% CI 11.2–210.0; P<0.001). ROC analysis demonstrated good predictive performance (AUC ≈0.75), with an optimal SI cutoff of 0.80 (68% sensitivity, 80% specificity).  

Conclusion: PIH is a frequent complication of emergency intubation with significant adverse outcomes. Pre-intubation SI is a simple, rapid, and reliable predictor that may facilitate early identification of high-risk patients and guide pre-intubation hemodynamic optimization.

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