Effect of tidal volume change on pressure-based prediction of fluid responsiveness in children

Abstract

Introduction: It is known that pulse pressure variation and systolic pressure variation cannot predict fluid responsiveness in children. In adults, the ability of these dynamic parameters to predict fluid responsiveness is improved by increasing tidal volume. We planned to investigate whether pulse pressure variation or systolic pressure variation can predict fluid responsiveness in children when augmented by increasing tidal volume by conducting a prospective study.

Methods: We enrolled children younger than 7 years who underwent cardiac surgery for atrial septal defect or ventricular septal defect. After sternum closure, pulse pressure variation and systolic pressure variation were continuously recorded while changing the tidal volume to 6, 10, and 14 mL/kg. Fluid loading was done with 10 mL/kg of crystalloids for 10 min, and stroke volume index was measured via transesophageal echocardiography. Children whose stroke volume index increased by more than 15% after the fluid loading were defined as responders to fluid therapy. We set primary outcome as the predictability of pulse pressure variation and systolic pressure variation for fluid responsiveness and measured the area under the curve of receiver operating characteristics curve.

Results: Twenty-six children were included, of which 15 were responders. At the tidal volume of 14 mL/kg, the area under the curves of receiver operating characteristics curves of pulse pressure variation and systolic pressure variation were 0.576 (p = .517) and 0.548 (p = .678), respectively. The differences in dynamic parameters between responders and nonresponders were not significant.

Discussion: Failure of pulse pressure variation or systolic pressure variation at augmented tidal volume in children may be due to difference in their arterial compliance from those of adults. Large compliance of thoracic wall may be another reason.

Conclusions: Augmented pulse pressure variation or systolic pressure variation due to increased tidal volume cannot predict fluid responsiveness in children after simple cardiac surgery.

Keywords: child; fluid therapy; thoracic surgery; tidal volume.