Original contribution Oblique approach for ultrasound-guided radial artery catheterization vs transverse and longitudinal approaches, a randomized trial ☆,☆☆,★ Usama Elsayed Mohammed Abdalla, MD ⁎, Alaa Elmaadawey, MD, AlRefaey Kandeel, MD Lecturer of Anesthesia and Surgical Intensive Care, Mansoura University, Egypt abstract article info Article history: Received 28 October 2015 Received in revised form 15 September 2016 Accepted 27 October 2016 Available online xxxx Study objective: To investigate the value of using a new technique for ultrasound-guided radial artery catheteri- zation; oblique approach; vs transverse and longitudinal views are the traditionally used approaches aiming to combine benefits and avoid drawbacks of aforementioned approaches. Design: A prospective randomized nonblinded study. Setting: Gastroenterology Center, Mansoura University, Egypt from February 2015 to August 2015. Patients: One hundred twenty-six surgical and intensive care unit patients indicated for arterial catheterization. Intervention: Patients were randomly allocated into 3 groups according to the US-guided technique used; group T (n = 42) using transverse view, group L (n = 42) using longitudinal view, group O (n = 42) using oblique view. Measurements: Primary objective was overall success rate; secondary objectives were first attempt success, time to cannulate, and operator satisfaction with the used technique. Main results: Forty-two patients were included for each study group. Overall success rate of radial artery cathe- terization was significantly higher in group O than in group T and clinically higher than group L (60% for group T, 70% for group L, 90% for group O; P b .02). Likewise, time needed to cannulate the radial artery was significantly lower in group O than in both group T and group L (28 ± 19 s for group T, 66 ± 5 s for group L, 16 ± 7 s for group O; P b .00]. Conclusion: These results support the conclusion that the oblique approach for US-guided radial artery catheter- ization may replace the 2 classic approaches owing to its superior success rate, higher first attempt success and shorter time consumed for catheterization with more operator satisfaction after the procedure. © 2016 Elsevier Inc. All rights reserved. Keywords: Radial Catheterization Ultrasound Guidance 1. Introduction Arterial catheterization is a commonly performed invasive proce- dure in the intensive care unit (ICU) and operating theater, facilitating accurate hemodynamic monitoring and frequent blood sampling. The procedure may be challenging especially in patients with hypotension, edema, and obesity, is often difficult, and may require multiple at- tempts. Such repeated attempts may lead to more difficult catheteriza- tion due to arterial spasm or injury, and may also increase the incidence of thrombosis and hematoma formation [1]. The radial artery is the commonest site for catheterization owing to its superficial course and its dual arterial supply to the hand [2]. Traditionally, radial artery was located through palpation of the pulse depending on the anatomical landmarks. However, anatomical variations, obesity, hypotension, edema, and atherosclerosis may render artery localization via palpation a difficult or even impossible task [3]. Recently, ultrasound-guided cen- tral vein catheterization offered the advantages of increased success rate, patient safety, and cost effectiveness [4,5]. Building on these re- sults, US guidance has been introduced into arterial catheter insertion seeking the same advantages. Up to our knowledge, there are 2 ap- proaches for US-guided radial artery catheterization which are the fol- lowing: the long access (in-plane or longitudinal) and the short access (out-of-plane or transverse) approaches with different degrees of suc- cess for each technique [3,6,7]. The aim of the study is to confirm our hy- pothesis that oblique US guidance during radial artery catheterization using oblique (out-of-plane) technique may improve the success rate of radial artery catheterization from the first attempt and may shorten the duration for successful catheterization. 2. Patients and methods After approval of institutional research board of Faculty of Medicine, Mansoura University, Egypt, this study was carried out in Mansoura University Hospitals. Consent was taken from 126 (ASA I-II surgically listed or ICU admitted) patients indicated for radial artery Journal of Clinical Anesthesia 36 (2017) 98–101 ☆ Trial registry: www.clinicaltrials.gov; Identifier: NCT02550223. ☆☆ Funding: no funding resources to be declared. ★ Conflict of interest: None. ⁎ Corresponding author at: Dakahleyya Government, Geihan St, Gastroenterology Center, Second Floor, Liver Transplant ICU, Mansoura City 35516. Tel.: +20 1028842265. E-mail addresses: usamaelsayed20@yahoo.com, usamaelsayed82@gmail.com (U.E.M. Abdalla). http://dx.doi.org/10.1016/j.jclinane.2016.10.016 0952-8180/© 2016 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Journal of Clinical Anesthesia