CVP vs. dynamic hemodynamic parameters as preload indicators in hemodynamically unstable patients after major surgery

Abstract

Introduction. Adequate circulating blood volume is essential for the good outcome in postoperative patients. Therefore, the primary resuscitation question is how to assess the circulating volume. The aim of this study was to compare the central venous pressure (CVP) and dynamic LIDCO parameters as markers indicating preload in surgical patients. Materials and Methods. This prospective study included 24 patients hospitalized after major surgery at the surgical intensive care unit of the University hospital Zagreb, Croatia. The patients were mechanically ventilated, without spontaneous breathing attempts and in sinus rhythm. Patients were divided into 2 groups, hemodynamically stable and hemodynamically unstable. The CVP was measured as a static parameter while the stroke volume variation (SVV) and pulse pressure variation (PPV) were measured as the dynamic parameters. Results. Study groups were comparable in terms of gender, age and body mass index. The difference in the CVP between the hemodynamically stable (13,2±3,74 mmHg) and hemodynamically unstable group of patients (10,1±5,6 mmHg) was statistically insignificant (p=0,144). Differences in SVV (10,2±6,48% in stable compared to 18,8±7,04% in unstable group) and PPV (11,5±6,65% in stable compared to 18±6,32% in unstable group) were both statistically significant with p values of 0,005 and 0,022 respectively. Conclusion. The study confirmed the inability of CVP to provide valid assessment of the preload as a reason for hemodynamic instability in comparison to dynamic LiDCOTMplus system parameters in mechanically ventilated major surgical patients.