Neonatal long lines: localisation with colour Doppler ultrasonography

Determination of Accurate Position of Umbilical Venous Catheters in Premature Infants

OBJECTIVE

The aim of the study is to determine the most accurate length and position of umbilical venous catheter (UVC).

STUDY DESIGN

This prospective study included premature infants who were admitted to the neonatal intensive care unit with inserted UVC between January 1, 2014 and December 31, 2015. The length of UVC was calculated according to the Shukla formula [(3 × birth weight + 9)/2 + 1] and the catheter was inserted under sterile conditions. After the insertion, umbilical catheter was first evaluated through chest X-ray and then with echocardiography to confirm its position. Catheters seen on the chest X-ray at the level of T9-T10 vertebrae were classified as "accurate position," those seen above T9 vertebra as "high position," and the catheters identified below T10 vertebra were classified as "low position."

RESULTS

A total of 68 infants smaller than 36 weeks of gestation were included in the study. In echocardiographic evaluation, 80% of the cases identified as in the "accurate position," 100% of the cases classified as in a "high position," and 33% of the cases defined as in a "low position" on the chest X-rays were found to be intracardiac. In our study, length of the catheter calculated according to the Shukla formula was intracardiac in 88.2% of premature infants.

CONCLUSION

Radiography alone is not sufficient for the determination of adequate position of umbilical catheter, especially in premature infants. Specialists practicing in neonatal intensive care units could improve themselves and evaluate UVC with echocardiography, making this a routine part of clinical practice. Echocardiography-guided fixation of the catheter will reduce the complications related to catheter malposition.

KEY POINTS

· Shukla formula is commonly used to calculate the adequate length of UVC.. · Chest X-ray is the most widely used modality for locating the tip of UVC.. · Echocardiography can be conveniently used for the determination of adequate position of UVC..

Umbilical venous catheter position: evaluation by ultrasound

OBJECTIVE

Umbilical venous catheter (UVC) insertion is frequently performed in critically ill neonates, with catheter position evaluated by an abdominal radiograph. The position of the catheter can be difficult to assess based on supine film alone. We aimed to determine whether ultrasound enables precise evaluation of the catheter tip position.

METHODS

We prospectively evaluated UVC position in 75 neonates by ultrasound and supine abdominal radiograph. Distance from the catheter tip to the diaphragm was measured for both modalities. Anatomical location of the catheter was recorded for both studies. The Student's t-test was used to compare the means of the differences in catheter position on radiograph and ultrasound.

RESULTS

In 46 patients there was no difference in the distance between the catheter tip and the diaphragm on ultrasound and radiograph. In 29 babies there was a difference of 1-to-7 mm. Ultrasound identified malposition of the catheter in three cases in which the position of the catheter on the plain film was deemed acceptable.

CONCLUSIONS

Our study suggests that ultrasound is reliable and may replace plain radiograph for the identification of the UVC position, preventing complications from malposition, and reducing exposure to ionizing radiation.

The reliability of 2D and colour Doppler ultrasound in localising longline position

BACKGROUND

The position of percutaneously inserted central venous catheters (longlines) in neonates is critical, as malpositioned longlines are associated with potentially fatal complications.

AIM

To determine if cardiac ultrasound (two-dimensional (2D) and colour Doppler) is useful in evaluating longline position, when compared with the position identified by contrast radiography.

SETTING

Single level 3 neonatal unit.

PARTICIPANTS

Forty-four neonates undergoing insertion of 24-gauge silastic longlines between July 2004 and September 2005.

METHODS

Infants who had a longline inserted underwent echocardiography by a novice and an experienced operator. Operators identified longline position using a 2D then colour Doppler echocardiography during a rapid bolus infusion of saline. The position was identified from contrast radiography by two independent observers.

RESULTS

Using 2D echocardiography, the novice and experienced operators could identify 41 and 59% of longlines, respectively. However, only 34% of longlines were identified by both operators. In 15 infants whose longline positions were identified by both operators, there was agreement in only eight infants (53%). Colour Doppler improved the experienced operator's success but did not assist the novice operator. For radiographs, there was 68% agreement on longline position between observers. The experienced echocardiographer located three (7%) longlines within the heart that from radiographs were thought to be in a proximal central vessel.

CONCLUSIONS

This technique is experience-dependent and complements rather than replaces the use of contrast radiography. However, some infants with an apparently acceptable longline position on contrast radiography have longlines located within the heart on echocardiography.