Usefulness of intrathoracic blood volume in the early phase of hemodynamic instability of patients with sepsis or septic shock

Introduction

Previous studies in cardiac surgical and ARDS patients suggested that the intrathoracic blood volume index (ITBVI) is a more reliable indicator of cardiac preload than the pulmonary capillary wedge pressure (PCWP). Since these studies were under controlled conditions, we analysed the value of both preload variables with respect to stroke index (SI) in patients with sepsis and septic shock under actual ICU conditions of frequent changes in ventilation, volume loading and catecholamine treatment.

Methods

We analysed 581 hemodynamic profiles in 57 septic patients (60 ± 15 years, SAPS II 53 ± 15, SOFA 15 ± 3) who received a 7.5 F pulmonary artery catheter and a 4 F flexible aortic catheter. Hemodynamic profiles were at least 15 min apart, the maximum time period was 24 h (8.25 ± 5.30 h).

Results

In all second profiles, changes in stroke index were accompanied by changes in ITBVI (r = 0.67) and not PCWP (r = 0.07). Increases in SI (n = 265) were more often associated with increases in ITBVI (n = 189. 71.3%) than in PCWP (n = 122, 46.0%). Decreases in SI (n = 256) were associated with decreases in ITBVI in 176 (68.8 %) and for PCWP in 119 cases (46.5%).

Conclusion

In the early phase of hemodynamic stabilisation of patients with sepsis or septic shock, ITBVI is a more reliable indicator of cardiac preload than the PCWP.