Umbilical artery catheters in the newborn: effects of catheter design (end vs side hole)

Cover Sheet

Short title: Umbilical artery catheters: catheter design
Reviewer(s): Barrington KJ

Date of most recent amendment: 24/11/1998
Date of most recent substantive amendment: 18/11/1998
Date next stage expected: / /

Contact
Dr Keith Barrington
Associate Professor
Pediatrics
University of California, San Diego
200 W Arbor Dr
San Diego
CA USA
92103-8774
Telephone 1: 1 619 543 7586
Telephone 2: 1 619 543 3759
Facsimile: 1 619 543 3812
E-mail: kbarrington@ucsd.edu

Sources of support for the review

Acknowledgements

Potential conflict of interest
None

Abstract

Objective

To determine whether the design of an umbilical arterial catheter influences the frequency of ischemic events, aortic thrombosis, intraventricular hemorrhage, mortality or necrotising enterocolitis in newborn infants.

Search strategy

Randomized and quasi randomized controlled trials of umbilical catheterization use were obtained from the following sources:
1. Effective Care of the Newborn Infant, edited by JC Sinclair and MB Bracken.
2. Medline Search using Melvyl Medline Plus and the keyword headings 'Umbilic#', 'Catheter#' and subject heading 'Infant, Newborn'
3. Search of personal data files

Selection criteria

Randomized trials in newborn infants of any birthweight or gestation.
Comparison of end hole catheters with side hole catheters.
Clinically important end points such as ischemic events or aortic thrombosis.

Data collection & analysis

There appears to be only a single trial which has addressed this issue (Wesstrom 1979).

Main results

End hole catheters are associated with a much decreased risk of aortic thrombosis compared to side hole catheters. RR = 0.27 (95% CI 0.11, 0.67)

Conclusions

Side hole catheters should be avoided for umbilical arterial catheterization in the newborn.

Background

Umbilical arterial catheters (UACs) are among the most commonly used monitoring methodologies in neonatal intensive care. Immediately after insertion of a UAC, local vascular compromise is frequently evident, usually in the form of blue or white toes, but occasionally with more severe and extensive ischemic manifestations. Aortic thrombi and renal ischemia have also been described. Some epidemiologic and case control studies have shown that the use of umbilical artery catheterization is statistically associated with the later development of necrotizing enterocolitis.

One of the variations in design of the catheters has been the development of end-hole or side-hole catheters. The side hole catheters often have an integral oxygen electrode at the tip necessitating the placement of the orifice away from the tip. In the early years of neonatal intensive care, feeding tubes, which also traditionally have a side hole, may have been used as catheters for umbilical artery lines. The position of the catheter hole could potentially lead to a difference in complication rates as the flow dynamics around the tip of the catheter will change. This may lead to a difference in the rate of clinically apparent ischemic events, or of aortic thrombosis.

This review updates the existing review of Umbilical artery catheters: catheter design, which was published in The Cochrane Library, Disk Issue 4 1997 (Barrington 1997).

Objectives

To determine whether the design of the catheter influences morbidity with the use of umbilical artery catheters, specifically whether aortic thrombosis or clinically recognized ischemic phenomena are affected.

Materials and Methods

Criteria for considering studies for this review

Types of studies
Randomized and quasi randomized clinical studies were selected. Clinically relevant outcomes were collated, with survival and long term disability being given the greatest weight. Both term and preterm infants were included.

Types of participants
Both term and preterm infants who require umbilical catheter placement were considered.

Types of intervention
Random allocation to an end hole catheter or a side hole catheter.

Types of outcome measures
1. Clinical vascular compromise, including blanching or cyanosis of the feet or toes
2. necrotising enterocolitis
3. intraventricular hemorrhage
4. death
5. aortic thrombosis
6. hypertension
7. hematuria

Search strategy for identification of studies

Methods of the review

Reports were first reviewed to determine whether there was a concurrent control group, and discarded if not. The method of assignment to control and intervention groups was then determined and if not random or quasi random, then the trial was discarded.

Each identified trial was assessed for methodological quality with respect to a) masking of allocation b) masking of intervention c) completeness of follow-up d) masking of outcome assessment.

Statistics: For categorical outcomes, typical estimates for relative risk and risk difference were calculated. For outcomes measured on a continuous scale, typical estimates for weighted mean difference were calculated. 95% confidence intervals were used. A fixed effect model was assumed.

Description of studies

The original search strategy retrieved 849 articles. These were further reduced by restricting the search by use of the terms prospective, random#, control#, comparative or clinical. When studies of animal subjects and of epidural catheterization were also removed, 233 reports remained. The abstract of each was read individually to determine if there was a possibility that the papers were reporting randomized prospective controlled trials.
No new trials comparing end hole and side hole catheters were discovered at the time of the November 1998 update to this review.

This final examination revealed only one trial investigating catheter design (Wesstrom 1979). The study was designed to randomly assign infants requiring umbilical catheter placement to one of four groups, high end hole, high side hole, low end hole or low side hole catheter. Infants were either preterm or term, requiring umbilical catheterization for numerous different reasons. After the first 15 months of the study the side hole groups were dropped, presumably because of the high incidence of aortic thrombosis, and for the final 4 months randomization was to high or low placement of end hole catheters only. The end hole catheter used was an 'Argyle' umbilical catheter; the side hole catheter was an Argyle feeding tube. Most catheters were 5 Fr size.

The major outcome variable was aortic thrombosis. This was determined either by single shot angiography at the time of removal of the catheter or at autopsy. Clinically apparent sequelae were said to be recorded, but are not clearly described.

Unfortunately the designs of the two largest prospective trials of umbilical artery catheter use, UACTSG 1992 and Kempley 1993, did not specify catheter type. Kempley's trial included both end and side hole catheters, of 3.5, 4.0 and 5.0 French sizes, but does not give results by catheter design, whereas UACTSG did not mention catheter design at all, but restricted the size to 3.5 Fr.

Methodological quality of included studies

Wesstrom 1979
Masking of allocation
Insufficient information presented to ascertain allocation masking.
Masking of intervention
Masking does not appear to have been attempted.
Completeness of follow-up
All infants appear to have been accounted for; there were nine infants among the 71 subjects for whom autopsy or angiography were not available.
Masking of outcome assessment
This was not attempted.
Other Comments.
The reason for dropping the side hole groups was not clearly described. No details of the randomization process are given. There is no hypothesis described and no sample size calculations are given.

Results

Side hole catheters appear to have a much higher incidence of thromboses than end-hole catheters from this single study (Wesstrom 1979). The relative risk for the occurrence of aortic thrombosis with end hole catheters compared to side hole catheters is 0.27 (95% CI 0.11, 0.67). The risk difference is -0.35 (95% CI -0.58, -0.12); this indicates that we can expect to prevent one case of aortic thrombosis in every three infants (95% CI 2, 8) who receive an end hold rather than a side hole catheter.

No other outcomes are well enough described to determine their relative frequency with end hole compared to side hole catheters.

Discussion

No other outcomes are well enough described to determine their relative frequency with end hole compared to side hole catheters.

Conclusions

Implications for practice

Currently, catheters designed with a side hole should not be used routinely for umbilical artery catheterization in the newborn.

Implications for research

Further studies to determine safety of catheters with non-standard designs should be performed. In particular the safety of the oxygen electrode tipped catheter which are used by some centers should be investigated.

Characteristics of Included Studies

Study: Wesstrom 1979
Method: Random assignment to one of 4 groups initially, high end hole, high side hole, low end hole or low side hole catheter. After the first 15 months the side hole groups were dropped and the final 4 months randomization was to high or low placement of end hole catheters only.
Participants: 62 term and preterm infants, requiring umbilical arterial catheterization for medical care.
Interventions: 39 infants had end hole catheters, 23 had side hole catheters
Outcomes: Thrombosis on angiography performed at removal was the primary outcome variable. Necrotising enterocolitis not determined; clinical vascular compromise not stated.

Characteristics of Excluded Studies

None

References to Studies

Section 1. References to studies included in this review

Wesstrom G, Finnstrom O, Stenport G. Umbilical artery catheterization in newborns. I Thrombosis in relation to catheter type and position. Acta Paediatr Scand 1979;68:575-581.

Other References

Section 5. Additional references

Kempley ST, Bennett S, Loftus BG, et al. Randomized trial of umbilical arterial catheter position: Clinical outcome. Acta Paediatr 1993;82:173-176.

Umbilical Artery Catheter Trial Study Group. Relationship of intraventricular hemorrhage or death with the level of umbilical artery catheter placement: A multicenter randomized clinical trial. Pediatrics 1992;90:881-887.

Section 6. Previously published versions of this review

Barrington KJ. Umbilical artery catheters: catheter design (Cochrane Review). In: The Cochrane Library Issue 4, 1997. Oxford: Update Software

Table of Comparisons

01.00.00 End hole compared to side hold catheters

01.01.00 Incidence of aortic thrombosis (RR)

01.01.00 Incidence of aortic thrombosis (RD)