Continuous minimally invasive cardiac output monitoring with the COstatus in a neonatal swine model: recalibration is necessary during vasoconstriction and vasodilation

Changes in blood volume indicators and dynamic indicators measured with transpulmonary ultrasound velocity during blood depletion and repletion in a neonatal swine model

BACKGROUND

Dynamic indicators such as pulse pressure and stroke volume variations can be measured to track changes in preload during hemorrhage, and evaluate fluid therapy. However, these dynamic indicators require mechanical ventilation, and might be affected by cardiac dysrhythmias and changes in vascular tone. Blood volume indicators may offer alternatives for assessing changes in volume status.

AIMS

The aims of this study were to measure changes in blood volume indicators and dynamic indicators during removal of blood in two stages and subsequent blood replacement in anesthetized, mechanically ventilated, neonatal pigs.

METHODS

In eight anesthetized, mechanically ventilated piglets (5-6 weeks old), cardiac index, stroke volume index, total end-diastolic volume, central blood volume, active circulating volume, pulse pressure variation, and stroke volume variation were measured during blood removal in two stages (15 mL kg^-1 each stage) and blood replacement (30 mL kg^-1 ). Values after each intervention were measured for each parameter.

RESULTS

All indicators differed from baseline after removal of 15 mL kg^-1 of blood, except for stroke volume variation. Differences between both stages of hemorrhage were only observed for indexed stroke volume, total end-diastolic volume, central blood volume, and pulse pressure variation.

CONCLUSION

Total end-diastolic volume and central blood volume changed during blood depletion and repletion, and differed between stages of hemorrhage. These indicators might be useful for assessing volume status instead of, or in addition to cardiac index and dynamic indicators.