Trimmed central venous catheters in pediatric cardiac surgery: Does height or weight correlate with the amount trimmed?

---

Background

Central lines are sometimes trimmed in small paediatric patients while on bypass to obtain optimal catheter tip positioning (SVC-RA junction).

Aims, Methods, Outcomes

• Single centre, retrospective study – Children’s Mercy Hospital, Kansas City, Missouri, USA.
• Three-year period.  Patients aged 3 months to 8 years with a 4 French 8cm central venous line (CVL).
• 147 cases had their CVL trimmed (35% all cases). An average of 2.17cm was removed (Min 0.3, Max 4.6cm)

1. Primary outcome. Was there a correlation between patient’s height or weight and length of catheter trimmed?
   a. Result = negligible correlation.
   b. This is probably because the insertion point in the neck was not standardised.
2. Secondary outcome. Rate of CLABSIs and VTE between trimmed versus non-trimmed central lines.
   a. Result = No CLABSIs in trimmed group, 1 instance of VTE in trimmed group
   b. There is a theoretical risk that trimming the tip may leave rough edges which are thrombogenic. Thrombus generation may increase infection rates. There is no previous published data on  the intraoperative trimming of CVLs and subsequent thrombus formation. Of note, PICC lines are routinely trimmed in paediatric patients.
   c. Given this study was retrospective, patients did not routinely undergo ultrasound to check for thrombus on the CVL prior to removal.

Conclusion 

Due to the difficulty in estimating the proper length of CVLs in small paediatric patients, placing an 8cm catheter in these patients and then trimming the distal tip while on bypass may be the most accurate way of properly positioning the catheter.

Some important points to consider:

1. Not all bypass procedures require a right atriotomy, therefore trimming the CVL is not possible in these cases.
2. The proximal port is set back from the tip (1.6 cm for ARROW catheters used in this study), meaning that the proximal lumen may extravasate first with catheter migration. However, if the CVL is trimmed >1.6cm all lumens will terminate at the tip.
3. The study centre avoids 5cm lines above 3 months of age due to an observed high rate of extravasation. The proximal lumen of 5cm CVLs is in a similar position to that described above.
4. Residual catheter length external to the skin has been shown to be an independent risk factor for CLABSIs. The study centre examined typically does not leave any catheter external to the skin.
5. The manufacturer’s (ARROW) insert precautions against altering the catheter length.

Reviewed by Dr Adam Keys