The Ratio of Femoral Vein Diameter to Femoral Artery Diameter to Predict Fluid Responsiveness in Children

An ultrasound probe will be used to first scan the area of the upper thigh just below the inguinal ligament directing caudally seeking for the femoral vessels. The femoral artery and vein could be observed simultaneously. Under normal conditions, pulsation is an indication of the femoral artery, and its companion is the femoral vein. The mean femoral vein diameter and femoral vein diameter (3-5 diametral lines in different directions) will be measured during cough, crying, or performing the Valsalva maneuvers.