Low cardiac function index predicts ICU mortality in patients with severe sepsis or septic shock

Introduction

Cardiac dysfunction is an important organ manifestation of severe sepsis, and its occurrence increases with disease severity. Similarly, patients suffering from acute heart failure are characterised by a poor cardiac performance and a high mortality. We compared the cardiac function index (CFI), a marker of myocardial contractility and other hemodynamic variables, in patients with acute heart failure and severe sepsis or septic shock and studied their relationship with ICU mortality.

Methods

Twenty-one patients requiring invasive hemodynamic monitoring were included. Diagnoses were severe sepsis or septic shock in nine patients (with no history of impaired ventricular function) and acute heart failure in 12 patients. In each patient, four hemodynamic measurements were performed during 24 hours of combined monitoring with a pulmonary artery catheter and a PiCCO catheter. The following parameters were simultaneously assessed: cardiac index by pulmonary artery catheter, CFI, pulmonary artery occlusion pressure, right atrial pressure, and global end-diastolic volume index. A nonparametric Mann–Whitney U test and Fisher's exact test were performed, as appropriate. Results presented as the median (interquartile range). Statistical significance defined as P < 0.05.

Results

The ICU length of stay was 17 (14–30) days in septic patients and 12 (5–19) days in heart failure patients (P = 0.13). Overall ICU mortality was 44% among patients with sepsis and 25% among those with heart failure (P = 0.40). In septic patients, the cardiac index in survivors was 5.2 (4.4–6.3) l/min/m² compared with 3.6 (3.3–3.8) l/min/m² in nonsurvivors (P < 0.001). In patients with heart failure, the cardiac index in survivors and nonsurvivors was 2.6 (2.1–3.0) l/min/m²and 2.8 (2.3–3.3) l/min/m², respectively (P = 0.54). The CFI in septic survivors was 6.7 (6.0–7.4) min^-1 compared with 3.5 (3.0–5.4) min^-1 in nonsurvivors (P < 0.001). The CFI in patients with heart failure who survived was 2.6 (2.0–3.0) min^-1 and 2.9 (2.3–3.2) min^-1 in those who died (P = 0.46). In both septic and heart failure patients, the pulmonary artery occlusion pressure, right atrial pressure and global end-diastolic volume index did not differ between survivors and non-survivors.

Conclusion

The cardiac index and CFI both provide prognostic information in patients with severe sepsis or septic shock. No relationship with ICU mortality was found in patients with acute heart failure.