EFFICACY OF SHOCK INDEX AND MODIFIED SHOCK INDEX AS PREDICTOR OF POST-INTUBATION HYPOTENSION IN CRITICALLY ILL PATIENTS PRESENTING IN ED

Abstract

Objective: To assess the predictive capability of pre-intubation shock index (SI) and modified shock index (MSI) in predicting post-intubation hypotension in critically ill patients who were seen in the emergency department. Study Design: Cross-sectional study. Place and Duration: Adult Emergency Department, Indus Hospital and Health Network, Karachi from January 2026 to June 2026. Methodology: A total of 96 critically ill adult patients who need emergency endotracheal intubation. Pre intubation SI (Heart Rate/Systolic Blood pressure) & MSI (heart rate/mean arterial blood pressure) were calculated. Post-intubation hypotension (PIH) was defined as a decrease in the SBP to 90 mmHg or less (≥20% decrease from baseline measured within 30 min after intubation). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and diagnostic accuracy of SI (greater than 1) and MSI (greater than 1.3) were derived with a reference outcome of PIH. The collected data were analysed in SPSS (26). Results: The overall mean age category was adult (14 years and above) and the likelihood was higher for males (60.4%). 32 patients (33.3%) developed post intubation hypotension. Shock index at a cut-off > 1, had a sensitivity of 56.2%, a specificity of 79.7%, PPV of 58.1%, NPV of 78.5 % and a diagnostic accuracy of 71.9 % when compared to endpoints. Modified shock index had a sensitivity of 53.1%, specificity of 67.2%, PPV of 44.7%, NPV of 74.1% and diagnostic accuracy of 62.5% at a cut-off >1.3. Conclusions: Pre-intubation shock index was more overall diagnostic accurate and more specific than modified shock index for prediction of post-intubation hypotension. Both are simple bedside measures that can be quickly calculated and can aid in risk stratifying critically ill patients before intubation, but have only limited sensitivity, which makes them poor, stand-alone predictors.