This was a randomized controlled trial conducted in a tertiary NICU. All neonates needing insertion of UVC were eligible. Babies who had UVC inserted earlier and undergoing repeat procedure and babies more than 7 days of age were excluded from the study. Institutional ethical committee approved this study. Informed consent was taken from the parents prior to insertion of UVC.

To achieve an 80% optimal position in the JSS group compared to 50% in the Shukla formula group with a power of 90% and alpha error of 5%, we needed to study 51 Subjects in both groups. The analysis was on an intention-to-treat basis.

Computer generated randomization was done. One of the authors calculated the desired length of insertion as per the randomization order and informed the doctor inserting the UVC. Under standard aseptic precautions, umbilical vein catheter was inserted to the desired length. A free back flow of blood into the syringe was considered as successful insertion. After the procedure, a check supine abdomen-chest X-ray was obtained and inter-preted by another author.

Tip of the UVC lying just above the diaphragm (T9 – T10), between upper border of T8 and T9 (lower one third of the cardiac shadow, just above the diaphragm) or at the liver edge was considered acceptable. Catheter tip in any of the other positions was considered unacceptable to use and hence had to be removed immediately. Cather tip seen in portal or hepatic veins was also considered unacceptable.

We randomized 104 neonates – 50 to Shukla’s formula and 54 to JSS formula group. Baseline characteristics of the study groups are depicted in Table I.

TABLE I Baseline Characteristics of Neonates

TABLE II Comparison of Acceptable Catheter Placements in the Two Groups

The success of placement of UVC to the desired length in the first attempt was similar in both groups. Table II depicts the rates of acceptability and non-acceptability of UVC placement using the two formulae.

The present study showed higher success rate in achieving the optimal position of UVC with JSS formula compared to using the Shukla formula.

On many occasions, the catheter remains in the normal course but either falls short or overshoots the optimal location rendering it unusable. Such issues can be addressed by a good formula or surface landmark which helps in calculating the appropriate length of the catheter to be inserted. Earlier studies have shown around 24% and 41% of the UVCs to be in optimal position when either Dunn or Shukla’s formula, respectively were used [10,11].

Our study has demonstrated that the proportion of catheters falling short of length to reach optimal position to be significantly lower in JSS formula group compared to Shukla’s formula group. This may also explain the lower proportion of the catheter in deviant course when Shukla’s formula was used. Had these catheters been advanced; some of them were likely to deviate and match the proportion in JSS formula group.

The strength of the study was that both the person inserting and the person reading X-rays were blinded to the formula used to estimate the depth of insertion. All the X-rays were read by a same investigator.

Limitation of the study was that the umbilical vein catheter was inserted by different physicians and the technique of insertion was bound to vary.

We conclude that the new JSS Formula achieves an optimal placement of UVC in a higher proportions than the modified Shukla formula.

Contributors: SK: study design, analyzing the data and preparing the manuscript; MM: collected the data, literature search and helped in manuscript preparation; DT: collected the data, did the literature search and contributed for analysis of data and preparation of the manuscript; SD: literature search, analysis of data and contributed to the study concept and design. He also provided critical inputs to manuscript preparation. All the authors approved the final version of manuscript for submission.

Funding: None; Competing Interest: None stated.