Association between Cardiac Index and Mortality in Patients Assessed on the Ward by a Nurse-Led Critical Care Outreach Team

Abstract

Derangements in cardiac output are associated with mortality in various patient groups but the relationship between cardiac output and mortality in critically ill patients on standard hospital wards has not been investigated. In this single-centre observational study, cardiac output was measured using a non-invasive supra-sternal Doppler technique in patients referred to a critical care outreach team. Data were collected at baseline and four hours later in 113 patients, of whom 28 died (24.8%) and 37 were admitted to critical care (32.7%). During this period, there was a significant decrease in mean cardiac index (2.74 L/min/m2 [95% confidence intervals 1.78–4.35] to 2.18 L/min/m2 [95% CI 1.54–3.21]; p=0.049) and stroke volume index (24 mL/m2 [95% CI 16–36] to 20 mL/m2 [95% CI 15–31]; p=0.02) in non-survivors, whilst in survivors these variables remained unchanged. There were no changes in heart rate or mean arterial pressure in either survivors or non-survivors. For 216 patients in whom only baseline data were available, only age, heart rate, arterial pressure, respiratory rate and temperature were independently associated with mortality. In conclusion, in the four hours following assessment on the ward by a critical care outreach team, cardiac index and stroke volume index were maintained in survivors, but decreased significantly in non-survivors. At baseline, neither variable was associated with mortality.