Clinical PaperComparison of ultrasound and X-ray in determining the position of umbilical venous catheters☆
Introduction
The umbilical vein is the easiest and most-used central venous access during neonatal resuscitation. The catheter is introduced into the umbilical vein, joining the inferior vena cava (IVC) via the venous portal system, and the ductus venosus (DV). The adequate tip position (TP) of the umbilical venous catheter (UVC) is the junction of the right atrium (RA) and IVC or the thoracic portion of the IVC, but misplacement is frequent. Echocardiographic examination led to UVC replacement in 56% of cases,1 and a more recent work found that only 23% of the UVCs were adequately positioned.2 In case of excessive length insertion, the catheter may be introduced into the RA, right ventricle (RV) or left atrium (LA) through the foramen ovale. Sometimes, the catheter may follow a branch of the portal vein (BPV) and assume an intrahepatic position. Misplacement is responsible for potential serious complications, such as myocardial traumatic damage, intracardiac thrombosis, arrhythmia, endocarditis, portal vein thrombosis or hepatic necrosis if vasopressors are infused into the portal vein.3 The optimal length of insertion may be estimated by a regression equation based on birth weight4 or shoulder–umbilical distance5 but these methods remain imprecise6 and do not show to the clinician the exact route of the catheter. Thus, the catheter TP must be confirmed, with thoraco-abdominal antero-posterior X-rays (TAX) being the method most frequently used. TAX may be improved by lateral X-ray, blood gas analysis or pressure monitoring.1 Ultrasonography (US) is increasingly used in intensive care, and has been shown useful in central catheter insertion and control of the TP.7, 8 Although US has been shown feasible as a replacement for TAX, the initial studies included only small numbers of patients.9 While two larger studies confirmed these results, the first2 was not designed to compare US with TAX, whereas the second focused on echocardiography and catheters that cross the DV.9 Since these findings suggested that US can be used as an adjunct to TAX, we prospectively compared the ability of US and TAX to determine UVC route and TP in newborns. We hypothesized that US was more accurate than TAX in this setting.
Section snippets
Methods
This study was performed between February 2008 and February 2009 in a 16 bed Paediatric and Neonatal Intensive Care Unit (NICU) of a university hospital. All newborns requiring UVC or admitted to the unit with an UVC were included in the study. Exclusion criteria were presence of thoracic and/or abdominal malformation or withdrawal of parent's consent. UVCs inserted in the unit were placed by a junior or senior intensivist, with length of insertion determined using a regression equation based
Results
Sixty-one UVCs were studied in 60 neonates. Mean gestational age was 34.7 ± 4.2 weeks and mean birth weight was 2496 ± 1081 g. Twenty UVCs were placed before admission in the NICU, and 41 were placed in our NICU. The quality of examination was assessed as good in 59 (97%) and 57 (93.4%) UVCs placements, for US and TAX respectively. Resident and senior radiologist findings were concordant in 30 of 31 placements (97%).
Discussion
In the present study, we have found that US is more accurate than TAX in determining UVC route and TP. UVCs allow rapid and painless central venous access, but can cause many complications, which are mostly linked to catheter misplacement.14, 15 Therefore clinicians must check accurately the correct IVC position of UVCs once inserted. The first difficulty is to cross the DV to obtain a central venous access. We found that only 45.9% of UVCs had a central route. These findings reveal the
Conclusion
Our results showed that TAX adequately determined UVC route but was not efficient in determining UVC TP, particularly in neonates with high birth weight. We now systematically control catheter position using US in our unit. US examination is not available in all NICUs, but we encourage NICU practitioners to develop this technique. Our results indicate that US should replace TAX for determining UVC route and tip position in most neonates.
Financial support
None.
Conflict of interest statement
No conflicts of interest to declare.
Acknowledgements
We thank Drs Karine Baumstarck and Anderson Loundou of the Unité d’Aide Méthodologique à la Recherche Clinique; Laboratoire de Santé Publique, Faculté de Médecine, Aix-Marseille Université, for statistical assistance.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.11.026.