Send letter to journal:
Re: Long line and its leakage. How simple measures help?

Dear Editor

We read with interest the article “Long line positioning in neonates: does computed Radiography improve visibility? By Evans A et al.[1]

The article addresses to the utility of picture archiving and storage systems (PACS) in determining the intravenous line positioning in comparison to hard copy films of computed radiography. It has found better visibility of the line tip with the use of PACS and hence use of this system would avoid repeated radiographs and contrast for the confirmation of position of line. However we wish to seek clarifications on the following points. In the study the long lines were inserted by pediatric clinicians using their standard procedure. We would like to know how much length of the catheter was inserted both in upper limbs as well as in lower limbs. The ideal position of the catheter tip is at the superior vena cava- right atrial junction or in the inferior vena cava at the level of the diaphragm.[2] Many neonatal respiratory and abdominal conditions such as Hyaline membrane disease, GBS pneumonia, pulmonary hemorrhage, & Necrotizing enterocolitis may obscure the visibility the line. There fore it is pertinent to know whether these conditions existed and if so how accurately could the tip be identified using PACS viz a viz hard copy. Further in how many cases were the tips correctly placed and what were the technical problems associated with use of these lines.

We Gupta et al. in this context would like to share experience in our unit. We often use Epicutaneo – Cava catheter 24 (G) Vygon,and the common technical problem encountered was the leakage at the junction of catheter with its hub. This has always resulted in the removal of the lines in the past. Wary of such incidents we innovated a technique where by the line could be salvaged and continued to be used .Using this technique prolonged the life of line by 48 hours and hence avoided the need of removal or insertion of a new line thus making both effort and cost effective.

We solicit authors’ comments for the above remarks.

References

(1) Evans A, Natarajan J and Davies C J. Long line positioning in neonates: does computed Radiography improve visibility? Arch Dis child fetal neonatal Ed 2004; 89: F44

(2) Fletcher SJ, Bodenham AR. Safe placement of central venous catheter: where should the tip of the catheter lie? Br J Anaesth 2000; 85:188-191

Send letter to journal:
Re: Digital Imaging and Long Lines

Dear Editor

We agree with the editorial comment that we badly need to know where long line tips are located (Phantoms 2004). However we cannot agree with the phrase, “The approach reported by Evans et al seems to beat that from Odd et al” the questions asked and the methodology of the two studies were quite different.

Firstly, the outcome assessed in the paper by Evans et al [1] was the identification of the line tip, whilst the outcome in our study was agreement regarding line tip location [2]. These are quite different issues. We have previously shown that even when experienced observers are confident that they can see the line tip there is only 72 % agreement regarding tip location [3]. As the editorial stated, the line tip position is the question we are faced with in clinical practice.

Secondly, in our study all three observers reported the images. In the Evans study, two different pairs of observers assessed each method (1 & 3 for hard copy and 2 & 3 for computed images) with only observer 3 assessing both modalities. Agreement between two observers is likely to be greater that that between three.

Thirdly, the high percentage of line tips identified using digital imaging may be biased by the fact that this figure is obtained when the findings of two radiographs (hard and soft copy) are compared to a figure obtained from review of a single radiograph (hard copy). The observer already has an idea as to the location of the line tip when reviewing the second image.

The Evans paper [1] is an important addition to the published experience of computer image modification techniques for identification of fine structures including long lines.[4] However this report of 95.6 % rate of identification of the long line tip using soft copy imaging is in contrast to the report by Soni et al [5] where the tip was identified by three different observers in 63 %, 74 % and 96 % of images. Although the published literature is supportive of the technique we concur with Evans et al that that enthusiasm should be tempered until further rigorous assessment is completed.

References

(1). Evans A, Natarajan J, Davies CJ. Long line positioning in neonates: does computed radiography improve visibility? Arch Dis Child Fetal Neonatal Ed 2004;89:F44-F45

(2). Odd DE, Page B, Battin MR, Harding JE. Does radio-opaque contrast improve radiographic localisation of percutaneous central venous lines. Arch Dis Child Fetal Neonatal Ed 2004;89:F42-F43

(3). Odd DE, Kuschel CA, Battin MR. Interobserver and intraobserver variation in identifying neonatal longline position: an internet-based survey. P76 Perinatal Society of Australia and New Zealand 7th Annual Congress. 2003.

(4). Strickland NH. PACS (picture archiving and communication systems): filmless radiology. Arch Dis Child 2000;83:82-86