Low cardiac index and high total peripheral resistance are independent predictors of mortality for acutely admitted medical patients

Abstract

Abstract Introduction Identification of critically ill and high-risk patients upon hospital admission represents a significant triage task in the emergency department. Rapid identification and treatment of these patients improves survival, reduces complications during admission, decrease hospitalization duration, and lower treatment cost. Hemodynamic variables such as cardiac index (CI) and total peripheral resistance (TPR) hold the potential to improve the diagnosis of critically ill patients by providing better prognostic value. Using arterial waveform and the model flow method, CI and TPR can be measured non-invasively. These methods are validated against thermodilution, which is the golden standard. Purpose The purpose of the study was to examine the association between CI, TPR, and all-cause mortality within 30 and 90-day among patients admitted to acutely the emergency department or cardiac care unit. Methods In this observational prospective cohort study, all patients were included from the emergency department and cardiac care unit. Patients of age 18 years or older admitted to the emergency department or cardiac care unit due to acute medical disease, were included. Patients with a life expectance of 3months or less and patients unable to give informed consent were excluded. Within the first 24 hours of admission, patients underwent a 10-minute non-invasive hemodynamic measurement using arterial waveform analysis and the model-flow method. Patients were followed up to 90 days after discharge. The endpoints 30- and 90-day mortality were obtained through electronic patient journals. Cox proportional-hazard models examined the association between CI, TPR, and outcomes. All hazard models were adjusted for age, sex, BMI, heart failure, early warning score, and Charlson comorbidity score. Results Between May 2019 and January 2023, we included 920 unselected patients from the department of emergency medicine (n=433) and cardiac care unit (n=487) from a metropolitan hospital. We observed a 3% 30-days mortality while 90-days mortality was 4.9%. The median value of CI was 3.3L, the lowest decile was 2L, and the highest decile was 4.7L. Patients with the lowest CI were older, had higher incidents of heart failure, and had more comorbidities according to Charlson’s comorbidity score (table 1). In Cox proportional hazard models, lowest decile of CI at admission was associated with a significantly higher risk of 30- and 90-days mortality. Total peripheral resistance was significantly associated with 90-day mortality (table 2). Conclusion Low CI ≤2.0 liter/min/m2, and high peripheral resistance measured non-invasively were associated with an increased risk of mortality among patients admitted to the emergency department or cardiac care unit. Non-invasive estimation of CI and TPR may assist in identifying high-risk patients.Table 1Table 2