Norepinephrine corrected shock index as an innovative hemodynamic based prognosticator in critically ill patients

Background: Hemodynamic instability in critically ill patients can be assessed by various hemodynamic valid indicators. One of these approved hemodynamics’ prognosticator is the Shock Index (SI), which integrates both the heart rate and systolic blood pressure in one composite indicator. Arbitrarily, higher vasopressor rate indicates poorer prognostic. Whatever, Norepinephrine, the preferred vasopressor in most shock related scenarios, has a tendency to increase heart rate beside its vasoconstriction associated systolic blood pressure augmentation.
Aim: In this study, we primarily aim to investigate the predictive power of a newer proposed composite hemodynamic prognosticator which integrates the average Norepinephrine infusion rates with the assessed patients’ Shock Indexes, and to explore its Sensitivity Indices regarding the critically ill patients’ major outcomes.
Methods: This study trial was a non-funded, non-sponsored, observational study, which was conducted retrospectively on the Intensive Care Unit (ICU) at King Hussein Medical Center, Royal Medical Services, Amman, Jordan, over 60 months between Jan 2018 and Dec 2022. Exclusion criteria including but not excluded to, admission days less than 24 hours and missing data more than 80%. All eligible investigated critically ill patients were dichotomously divided into 2 comparative NE×SI products’ cohorts; lower product’s (NE×SI<14.835 µg.bpm/min. mmHg) cohort (Cohort I) versus higher product’s (NE×SI≥14.835 µg.bpm/min. mmHg) cohort (Cohort II).  A Chi Square test were conducted across these 2 dichotomized cohorts. The Binary Logistic Regression (BLgR) analysis was conducted for the tested patients’ prognosticator (NE×SI) against the probability of being allocated to the Non-Survivors State (The Positive State) rather than to the Survivors State (The Negative State). The Receiver Operating Characteristic (ROC) and Sensitivity Analysis were processed to explore the area under the ROC curves (AUROC±SEM), optimal cut-off points, and the other sensitivity indices.
Results: Actually, 2528 and 3217 cases were processed as positive actual states (Positive OI, Non-Survivors) and as negative actual states (Negative OI, Survivors) respectively. The AUC±SEM for the NE×SI was significantly determined at 0.944±0.003 (95% CI; 0.938-0.949). The probability of the positive OI was 66.12% at the optimal operating cutoff point of 14.84 µg.bpm/min. mmHg. In this study, we constructed a BLgR model to prognosticate the admitted ICU patients’ mortality and was formulated as [e (-6.986+0.516× NE.SI) /1+ e (-6.986+0.516× NE.SI)].
Conclusion: Our results revealed that our proposed an innovative hemodynamic composited product had a reasonable constructed area under the curve with an interesting sensitivity index for prognosticating the admitted critically ill patients’ mortality rate.