Volume expansion and variation in haemodynamic parameters

Objective.

To assess correlations among variations in hemodynamic parameters during fluid volume loading.

Methods.

Prospective observational study in 2 intensive care units. Sixty patients requiring intravenous fluids underwent challenge tests with 300 mL of crystalloids over a 48-hour period. Percent change in hemodynamic parameters after infusion was measured. We used hierarchical cluster and principal component analyses to explore correlations among changes in hemodynamic responses.

Results.

The parameters that underwent the greatest median (interquartile range) percent changes were central venous pressure (24% [0.0%–41.7%]), pulse pressure (12.9% [0.0%–22.4%]), shock index (5.8% [2.7%–13.7%]), rate–pressure product (5.8% [3.8%–18.8%]), and systemic pressure difference (5.8% [–3.8%–18.8%]). There were strong correlations between percent changes in the following parameters: systolic blood pressure, pulse pressure, rate–pressure product, shock index, and systemic pressure difference. Central venous pressure was not correlated with any of the other hemodynamic parameters.

Conclusion. The relationships between changes in hemodynamic parameters after fluid loading are complex and must be taken into account if fluids are infused during resuscitation.