A randomized controlled trial of ultrasound-assisted technique versus conventional puncture method for saphenous venous cannulations in children with congenital heart disease

Table 1 The grading criteria of saphenous vein punctures

I Visible bilateral saphenous veins, no difficulty in puncture
II Only a saphenous vein visible, predictable difficult access
III No visible or palpable bilateral saphenous veins

ISSN: 1471-2253