Simple and Accurate Formula to Estimate Umbilical Arterial Catheter Length of High Placement
Suthida Sritipsukho MD*, Paskorn Sritipsukho MD**
Affiliation : * Department of Pediatrics, Faculty of Medicine, Thammasat University ** Graduate Studies Program, Faculty of Medicine, Thammasat University
Objective : The present study aimed to derive the new simple, reliable, and accurate formula based on a body
measurement parameter and not on reference graphs, to determine umbilical arterial catheter length of high
placement, between the sixth to tenth thoracic vertebral (T6-T10) levels. Accuracy among a variety of formulas
was also examined.
Materials and Methods : A prospective recruitment of 40 babies who had an umbilical arterial catheter placed
in the NICU, Thammasat University Hospital was studied. Insertional length for high placement was mea-
sured. The body measurement parameters were measured twice on each patient to indicate their reliability
properties. Three individual umbilical arterial lengths, from umbilical ring to anatomical points of T6, T8,
and T10 levels accordingly, were estimated by verifying the catheter tip against those anatomical points on
chest and abdominal radiograph. Correlation coefficient (r) between each parameter and the umbilical
arterial length to the T8 level was calculated.
Results : Suprasternal notch to superior iliac spine length (SSSL) was the selected parameter to derive a new
formula because of high reliability coefficient of 0.964, high correlation to the umbilical arterial length to the
T8 level (r = 0.906), and its simplicity to measure. The accuracy of the ‘SSSL’ to position the catheter tip at
T6-T10 was 90%.
Conclusion : The SSSL is simple and accurate for predetermination of the umbilical arterial catheter length to
position the catheter tip at T6-T10. It can be an alternative formula, especially where birth weight and total
body length are not available.
Keywords : Umbilical arterial catheter, Simple, Accurate, Estimation, Length, high placement
