Jeng et al evaluated several equations for estimating the length to insert a catheter into the umbilical artery. They modified the equations for Chinese neonates.


Goal: placement of tip between T7 and T9



(1) birth weight in kg

(2) distance from suprasternal notch to pubic symphysis in cm

(3) total body length in cm

(4) sagittal distance between a horizontal line through the shoulders and a horizontal line through the umbilicus


length of the arterial catheter in cm =

= (7 * (birthweight)) + 2

= distance from the suprasternal notch to the pubic symphysis in cm

= (0.333 * (total body length)) + 0.5

= (sagittal distance between shoulder and umbilicus) + 1


If an umbilical stump is present then its length needs to be included in the calculation.


NOTE: The estimate from the birthweight equation does not match the other equations. Performance may be better at low birthweights. Alternatively there was a mistranslation from the Chinese and a different multiplication factor is needed.


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