Methods: Infants between the age of 1 month to 2 years with normal weight and height were enrolled. Skin to muscle depth(STMD) and skin to bone depth(STBD) measurement using ultrasound at the mid-anterolateral thigh were performed by radiologist.
Results: Seventy-five infants were enrolled. STMD were ranged from 0.46 to 2.08 cm. STBD were ranged from1.31 to 3.56 cm.Twenty-nine infants (38.6%) had STBD less than 1 inch. Comparison between infants who had STBD less than 1 inch and those with STBD at least 1 inch, 69% of infants who had STBD less than 1 inch were male while 19% of infants who had STBD at least 1 inch were male (P=0.02). Infants who had STBD less than 1 inch had a significant lower body mass index (15.77 vs 16.88, respectively, p=0.02) and lower thigh circumference (22.75 vs 25.54, respectively, p<0.001). There was a significant positive correlation of thigh circumference and STBD (R= 0.7, P<0.001).Thigh circumference of 25 cm provides the sensitivity of 79.3% and specificity 50% in predicting STBD at least 1 inch.
Conclusions: A large proportion of infants may be a risk of having adrenaline prefilled syringe to intraosseous route when using 1 inch needle.