Cardiac and vascular findings using ultrasound in hypovolemic children.

Background: Ultrasound is a non-invasive tool that helps assess volume status.

Objectives: To assess the dehydration and passive leg raising impact on ultrasound-derived cardiac and inferior vena cava parameters to improve early detection of hypovolemia in children.

Design: Prospective observational study in a tertiary paediatric intensive care unit.

Methods: We recruited 66 healthy children 8-14 years old who fasted in Ramadan. Inferior vena cava diameter, inferior vena cava collapsibility, velocity time integral and maximum velocity (Vmax) were measured at left ventricle outflow tract pre- and post-fasting, with and without passive leg raising. Aorta diameter in systole was also measured pre- and post-fasting.

Outcome measures: Inferior vena cava diameter and collapsibility, velocity time integral and Vmax with and without passive leg raising, pre and post fasting, and inferior vena cava/Ao ratio pre and post fasting were measured.

Results: Median percentage of weight loss after fasting was 1.1% (range, 0%-3.9%). Inferior vena cava maximum diameter and inferior vena cava/aorta did not change significantly after fasting (p < 0.05). Inferior vena cava diameters increased and inferior vena cava collapsibility decreased after passive leg raising (p < 0.001) pre and post fasting. Velocity time integral increased with passive leg raising (p < 0.001) but was not affected by fasting (p = 0.17). Vmax increased with passive leg raising and decreased in fasting (p = 0.001).

Conclusion: Passive leg raising affected ultrasound measurements. Left ventricle outflow tract Vmax was affected by fasting/mild dehydration, and further trials are needed to confirm its value in predicting hypovolemia in children.

Limitations: There was no significant effect of dehydration on the measurements probably because of the small sample and mild dehydration. This cannot be generalised because it is a single-centre study and younger children were not included.