Usefulness of Cardiac Index to Predict Early and 30-Day Mortality in Non-Cardiac Patients Being Admitted to Intensive Care Units

Introduction: Cardiac index is a hemodynamic parameter defined as the ratio of the cardiac output, i.e., the volume of blood ejected from the left ventricle in 1 min, to the body surface area. This study aimed to assess the cardiac index to predict early and 30-day outcomes of non-cardiac patients being admitted to intensive care units using a non-invasive approach. Materials and Methods: This prospective cohort study included 31 non-cardiac patients who were consecutively admitted to the intensive care units of Rasoul-e-Akram Hospital, Tehran, Iran, in 2016. On admission, the simplified acute physiology score II to predict mortality and the cardiac output (by two-dimensional echocardiography) of each patient were determined. The cardiac index was calculated by dividing the cardiac output by the body surface area. In-hospital mortality and complications were assessed, and the association between simplified acute physiology score II and cardiac index was determined. The patients were followed-up 30 days after discharge by telephone to determine late death, occurrence of myocardial infarction, readmission, or re-hospitalization. Results: The mean cardiac index was significantly lower among the patients who died in intensive care units than in those who survived (2.86 ± 0.63 versus 3.70 ± 0.49, p = 0.006). A significant inverse association was found between Simplified Acute Physiology Score II and cardiac index (r = −0.539, p = 0.002). The length of hospital and intensive care units stay was not associated with Simplified Acute Physiology Score -II or cardiac index. The receiver operating characteristic curve analysis revealed that the cardiac index was effective in predicting in intensive care units mortality (area under curve = 0.857, p = 0.007). The best cut-off value for the cardiac index to predict in intensive care units mortality was 3.35, yielding a sensitivity of 83.3% and a specificity of 80.0%. Conclusion: Measuring the cardiac index during intensive care units admission using a noninvasive approach even in non-cardiac patients can predict in intensive care units mortality with high sensitivity and specificity.