Relationship of stroke volume variation, pulse pressure variation and global end-diastolic volume in patients undergoing brain surgery

Introduction

Monitoring intravascular volume in patients with intracranial pathology is often mandatory for maintaining hemodynamic stability [1, 2]. Cyclic changes in cardiac stroke volume [1, 3] and pulse pressure induced by positive pressure ventilation as well as target values of global end-diastolic volume index (GEDVI) (ml/m²) [2] allow volume therapy guidance. The relationship between stroke volume variation (SVV) (%) and pulse pressure variation (PPV) (%), as well as between SVV or PPV and values of GEDVI has not been established in patients with intracranial pathology.

Methods

In this prospective investigation the correlation between dynamic and static hemodynamic parameters of 38 patients undergoing brain surgery was studied. Measurements were performed using the PiCCO technology. For statistical analysis, nonparametric correlation analysis and hypothesis testing were applied.

Results

SVV correlated significantly with PPV (r₂ = 0.87, P < 0.001). Neither SVV (r₂ = 0.14, P = 0.13) nor PPV (r₂ = 0.07, P = 0.81) correlated with GEDVI. Threshold values for SVV (9.5%, 11.6%) as well as for PPV (12.5%) allowed discrimination between groups with significantly different values of stroke volume index, while failing to discriminate between groups with significantly different values of GEDVI. Dichotomizing the patients into groups of GEDVI ≤680 ml/m² and >680 ml/m² resulted in groups with significantly different values of stroke volume index as well while failing to discriminate between groups with significantly different values of SVV and PPV.

Conclusions

Static (GEDVI) and dynamic (SVV, PPV) parameters of cardiac preload may reflect different properties of the cardiovascular system. The combination of SVV, PPV, and GEDVI may offer more precise information on the cardiovascular system than either parameter alone.