The following is a summary of “Association of Shock Index with Echocardiographic Parameters in Cardiac Intensive Care Unit,” published in the October 2023 issue of Critical Care by Tabi et al. 

Elevated shock index (SI), the heart rate (HR)/systolic blood pressure(SBP) ratio, is linked to adverse outcomes. Researchers performed a retrospective study to determine the hemodynamic underpinnings of an elevated shock index in cardiac intensive care unit (CICU) patients using 2D and Doppler transthoracic echocardiography (TTE).

The study analyzed Mayo Clinic CICU admissions from 2007 to 2018 with patients in sinus rhythm during TTE. SI was calculated using HR and SBP at the time of TTE, and patients were grouped based on SI values: <0.7, 4012 (64%); 0.7–0.99, 1,764 (28%); and ≥1.0, 513 (8%). Pearson’s correlation coefficient evaluated associations between continuous variables.

The result demonstrated of 6,289 unique CICU patients, 58% had acute coronary syndrome. The median age was 67.9 years, with 37.8% being female. The mean SI was 0.67 BPM/mmHg. As SI increased, several left ventricular (LV) systolic function and forward flow markers declined, including left ventricular ejection fraction (LVEF), fractional shortening, left ventricular outflow tract (LVOT) velocity time integral (VTI), stroke volume, LV stroke work index, and cardiac power output. Both biventricular filling pressures and right ventricular function deteriorated with higher SI. Most TTE measurements reflecting LV function and forward flow were inversely correlated with SI, including LV stroke work index (r = -0.59) and LVOT VTI (r = -0.41), as well as systemic vascular resistance index (r = -0.43) and LVEF (r = -0.23).

The study found that elevated shock index in CICU patients is associated with poor heart function and blood flow, making it a useful tool to identify patients who need further evaluation.

Source: sciencedirect.com/science/article/abs/pii/S0883944123001946