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  Table of Contents 
Year : 2021  |  Volume : 22  |  Issue : 1  |  Page : 35-39

Ultrasound-guided radial artery cannulation in pediatric surgical patients <24 months of age

1 Department of Anesthesiology and Critical Care, Army Hospital (Research and Referral), New Delhi, India
2 Department of Pediatrics, Army Hospital (Research and Referral), New Delhi, India

Date of Submission27-Jun-2020
Date of Decision29-Jun-2020
Date of Acceptance20-Jul-2020
Date of Web Publication22-Feb-2021

Correspondence Address:
Dr. Ashish Kumar Simalti
Departmenrt of Pediatrics, Army Hospital (Research and Referral), New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TheIAForum.TheIAForum_87_20

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Background: Arterial cannulation is increasingly becoming the standard of care in the perioperative management of complex pediatric surgeries and in patients with congenital cardiac anomalies. These indwelling arterial cannulas are used for invasive blood pressure (IBP) monitoring and blood gas analysis. With advent of ultrasound era, there is rising interest for its application in pediatric arterial cannulation. However, limited literature is available on its benefit in terms of success rate and complications.
Aims: The aim of this study is to assess the success rate and complications when ultrasound guidance was used for arterial line insertion in the pediatric surgical patients.
Setting and Design: Operation Theatre of Tertiary Care Centre / Prospective Observational Study.
Statistics: Descriptive statistics.
Materials and Methods: This study was conducted in children aged below 24 months requiring IBP monitoring during surgery. Parameters observed included rate of successful cannulation subdivided into first attempt success rate, successful cannulation within first two attempts, time to successful cannulation, and number of cannula. Complications namely hematoma and ischemic damage were also documented.
Results: A total of 258 children were included in this study. We achieved successful radial artery cannulation in 95.74% patients, of which 77.9% were in first attempt while 8.1% required two attempts. The median time taken was about 168 s. In 33 (13%) cases, the site was changed before pricking based on thrombus or very narrow diameter of the artery. Hematoma formation was seen in 21 (8.1%) children, and only 2 (0.7%) children had features of ischemia in the distal part requiring removal of the cannula from radial artery.
Conclusions: This study emphasized benefits of routine use of ultrasound in terms of higher chances of first-attempt success, lesser time for cannulation, lesser time taken, and more objective training benefit from ultrasound-guided radial artery cannulation in pediatric patients less than 24 months of age.

Keywords: Arterial line, pediatric, radial artery, ultrasound

How to cite this article:
Parikh B, Simalti AK, Shankhyan V K, Joshi S. Ultrasound-guided radial artery cannulation in pediatric surgical patients <24 months of age. Indian Anaesth Forum 2021;22:35-9

How to cite this URL:
Parikh B, Simalti AK, Shankhyan V K, Joshi S. Ultrasound-guided radial artery cannulation in pediatric surgical patients <24 months of age. Indian Anaesth Forum [serial online] 2021 [cited 2021 May 9];22:35-9. Available from: http://www.theiaforum.org/text.asp?2021/22/1/35/309840

  Introduction Top

Invasive blood pressure (IBP) monitoring and frequent arterial blood sampling for blood gas and acid–base monitoring have become the essential part of hemodynamic monitoring of critical children admitted in pediatric intensive care unit (PICU) and undergoing major surgery. Radial artery is the most commonly selected site for arterial cannulation due to collateral circulation, easier access, and favorable anatomy.[1] Cannulation of radial artery by palpation is technically difficult in children because of small size of arteries, diffuse pulsation due to relative tachycardia, lesser stroke volume and elastic blood vessels.[2] These factors become even more pronounced in hemodynamically unstable child. Unlike central venous cannulation, use of ultrasound in the arterial line insertion has not been studied extensively.[3] This prospective observational study was designed to assess the efficacy of ultrasound-guided radial artery cannulation. The primary objective of the study was to find the rate of successful cannulation of radial artery under ultrasound guidance, with associated hematoma/ischemic complications as the secondary objective.

  Materials and Methods Top

This prospective observational study was conducted in operation theater of a tertiary care center of North India which acts as referral center for pediatric surgery. Institutional ethics committee clearance certification was sought and obtained before the study begun. Informed written consent was obtained from all the study participants before including them in the study after explaining them implications of study. At our center, 50–60 pediatric surgeries are carried out every month. This study was conducted on patients planned to undergo major pediatric surgical procedure for various indications. The study period was of 24 months from January 2018 to December 2019, and all the children below 24 months requiring IBP monitoring during surgery were included. Children who came with arterial line from PICU or when radial artery was not available because of prior attempts or surgical reason were excluded from the study. Patients already in shock and on vasopressors were also excluded. In our center, all arterial cannulations in pediatric surgical cases are being done under ultrasound guidance by experienced operators. Experienced operators were defined as one with >20 successful ultrasound-guided arterial cannula in the specified age group, i.e., <24 months. In the span of 2 years, 258 radial artery cannulations were performed using ultrasound guidance.

Data collection

Demographic data and information on the arterial cannula were recorded for each child at the time on cannulation. The data were entered on with respect to the age, sex, weight date, and time of insertion. The following parameters were recorded – rate of successful cannulation which was defined as success without change of site. Successful cannulation was further subdivided into first-attempt success rate, successful cannulation within the first two attempts, time to successful cannulation, and number of cannula used for the procedure. The time for successful cannulation was measured from the time of piercing the skin to recording the arterial trace on the monitor. After cannulation, the rate of complications namely hematoma and ischemic damage was also documented. Thrombosis was diagnosed by direct ultrasound visualization of the arterial lumen and with flow confirmed by color Doppler. Ischemia was diagnosed clinically based on signs of poor perfusion, namely pallor, prolonged Capillary Filling Time (CFT), and cool extremity.

Statistical analysis

Descriptive statistics are presented as frequencies, means, and medians with standard deviations or ranges, resulting from a nonnormal distribution where appropriate. The frequency of arterial cannula-related hematoma/ischemic complication was calculated on the basis of the total number of arterial catheter inserted.


The technique used for ultrasound-guided arterial cancelation was “short-axis out-of-plane approach” with dynamic needle tip positioning.[4],[5] A portable ultrasound machine (Sonosite, Fujifilm USA) with a high-frequency linear probe (6–13 MHz) was used for arterial line cannulation. The wrist was extended by placing gauze roll below the wrist and fixed. Probe was covered in the sterile disposable cover with conducting jelly for interface. Radial artery was localized by doing a scout scan placing the probe perpendicular to the wrist with the left hand [Figure 1]. The artery was identified by visualizing the pulsation and confirmed by color Doppler. The probe was adjusted to keep the artery in the center of the screen. The gain and depth were adjusted to give the best view of the artery. With the right hand, a preselected appropriate-sized cannula was inserted just below the ultrasound probe at the center at an angle of 45°, and the needle was advanced slowly to visualize the needle as bright white spot between the skin and the artery [Figure 2]. The needle was then advanced slowly to puncture the anterior wall of the artery, with constantly aligning the ultrasound probe keeping needle tip visible all the time. The probe can also be tilted towards the needle initially to visualise the needle tip entering the artery gradually making it perpendicular and then titling it away following the needle tip as it is advanced in the artery (Fanning).[5] The needle tip at the point looked like hyperechoic bright spot with a dark halo. A flashback confirmed the position of needle in the artery. The angle was then reduced to 30° to flatten to angle, and the needle was further advanced 0.5–1 cm further with probe tilted or moved proximally so to keep the needle tip under vision (walk down). Once the needle tip and cannula were in position with positive flash back, the probe was then removed and cannula advanced in the artery and connected to primed arterial high-pressure line connected to pressure transducer. Confirmation of arterial trace was taken as the end point of the procedure.
Figure 1: Technique of using ultrasound probe for radial artery cannulation

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Figure 2: Radial artery localized on ultrasound with needle in lumen

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  Results Top

During the study period, radial artery insertion using ultrasound was performed in 258 children below 24 months of age in the operation theater. The median age of children was 11 months ranging from 1 to 24 months. Demographic characteristics of these children are summarized in [Table 1]. Out of these 258 children, 144 (56%) were males. Median weight was 9 kg (interquartile range [IQR] 3–19). Eighty-five (33%) children were taken as emergency surgery, while remaining 173 (67%) were elective cases. Sixty-one (23.6%) of these children had been punctured at the same site before in the ward, which makes arterial puncture more difficult because of possibility of thrombosis at the site of puncture. Studied outcomes are presented in [Table 2]. We had overall success in 247 (95.74%) out of which 201 (77.9%) were cannulated in the first attempt, while 21 (8.1%) cases required two attempts. Only in 11 cases (4.26%), the site had to be changed because of multiple failed attempts. The median time taken was about 168 s (IQR 124–306 s) from piercing the skin to registering the arterial trace on the monitor. Because of reduced number of attempts, total number of cannula used also reduced with most cases requiring only one cannula while few requiring more up to maximum of 4 (median 1 IQR 1–4). In 33 (13%) cases, the site had to be changed before pricking based on preexisting thrombus in the radial artery or very narrow diameter of the artery. There were not many complications related to procedure. Hematoma formation was seen in 21 (8.1%) children, and only 2 (0.7%) children had features of ischemia in the distal part requiring removal of the cannula from radial artery. Signs of ischemia resolved after few hours of observation and did not require any specific intervention.
Table 1: Baseline characteristics of cohort undergoing ultrasound-guided radial artery cannulation

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Table 2: Result of ultrasound guided arterial insertion

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  Discussion Top

For central vein localization and cannulation, ultrasound is recommended by most guidelines such as American Society of Anesthesiology Task Force[6] and NICE guidelines.[7] However, currently, there are no guidelines for role of ultrasound in the arterial line cannulation among pediatric population. In this study, we cannulated 258 children below 24 months of age with the help of ultrasound. Rate of successful cannulation in our was study was 95.7% which is lesser than 100% reported by Schwemmer et al. and greater than that reported by Tan et al. (85%) and Anantasit et al. (80.5%).[8],[9],[10] Similarly, first-attempt success rate in our was higher than that reported than Ishii et al. (69.4%), Schwemmer et al. (66.4%), and Anantasit et al. (60.6%).[8],[10],[11] A systematic review by Aouad-Maroun et al. including 444 arterial insertions showed that using ultrasound does improve the success rates of radial artery cannulation in pediatric population.[12] Conversely, Tan et al. and Ganesh et al. reported that there was no significant difference in the success rate between palpation method or ultrasound guidance among children aged below 24 months.[9],[13] The difference between these studies was that the operators in the studies considered by Aouad-Maroun et al.[12] were experienced anesthesiologists whereas those by Tan et al. and Ganesh et al. reported that operators were anesthetic fellows with relatively less experience.[9],[13] Since, in our study, operators were experienced, results are comparable to the studies meta-analyzed by Aouad-Maroun et al.[12] Eisen et al. also found similar success rate of 79% for radial artery catheter insertion among adult subjects. They found much higher rate of failure for female subjects (43%) as compared to male patients (5.6%).[14] We did not find any such difference among pediatric population probably because differences in the adipose tissue distribution and artery size are not very significant before puberty. Gao et al. compared benefits of ultrasound in pediatric as well as adult population and found it to improve chances of first-time cannulation.[15] This benefit was much more significant among children as compared to the adults (odds ratio of 1.73 for pediatrics as compared to 1.38 for adults).

In our study, 8.1% of the patients had successful cannulation in the second attempt making an 86% successful cannulation in first two attempts. Schwemmer et al. and Ueda et al. evaluated successful cannulation within the first two attempts and found a success of 100% and 53%, respectively.[8],[16] Again, the huge difference between these studies was because the fellows in the former were experienced in the ultrasound-guided arterial line placement as compared to inexperienced residents in the latter. Median time to successful cannulation reported was extreme variable in different studies ranging from as low as 38 s reported by Takeshita et al.,[17] 150.8 s by Schwemmer et al.,[8] 3.3 min by Anantasit et al.,[10] to nearly 8 min reported by Tan et al.[9] This disparity is attributable to the difference in defining the start and end point of measuring time. The number of cannula used for arterial cannulation has not been widely studied; however, our median value was similar to that reported by other investigators.[13],[17] Numerous studies have highlighted the benefit of ultrasound on reduced complications. Rate of hematoma formation on palpatory method has been reported to be as high as 53.3%.[10] The incidence of hematoma formation with use of ultrasound in pediatrics was 5%–12.2% and was reportedly reduced by 25%–40% when compared to palpatory methods.[10],[11],[18] Fewer studies have reported the ischemic complications during radial artery cannulation. Schindler et al. reported a 0.3% ischemic complications similar to our study.[18] The ischemia was transient and required removal of cannula, but there were no long term complications. One of the most common problems encountered in the arterial cannulation by palpatory method is inability to cannulate the artery after puncturing it. This could be due to thrombus from previous attempts which gets eliminated in ultrasound guidance technique as arterial lumen can be visualized and can be followed for sufficient length before attempting it. Furthermore, in ultrasound-guided arterial cannulation, the chances of puncturing the posterior wall is less, hence probably easier cannulation.[17] Other important cause is anatomical variation and arterial diameter. We changed the site in 33 cases based on these variations. This may have prevented this issue of inability to thread even after getting the back flow in our study. There are many confounders such as expertise of operator, age and weight of child, and strength of pulsation during palpation which impacts the rate of complications. Among the approaches used in ultrasound-guided vascular access short-axis out-of-plane approach is almost ubiquitous, whereas long-axis in-plane approach can also be used. Berk et al. found the longitudinal approach to be better as it reduced time and improved first-attempt success.[19] However, their study was conducted on adults patients, whereas our patients were infants/small children where the arterial diameters are smaller, and therefore, alignment may be more difficult and time-consuming as compared to the adult population group. Another important benefit was that the learning curve of ultrasound-guided arterial line placement was steep and acquired quickly as compared to palpatory method.[20],[21] This is difficult to quantify and hence was not included in the protocol; however, ours being a teaching hospital, it was an important benefit. The same findings were anecdotally documented by Miller and Bardin as they suggested that ultrasound-guided arterial insertion training can reduce the complications related to inexperienced operator[22] and recommended further research. Interestingly, Anantasit et al. found that their 2nd-year residents had a lower rate of success compared to the 1st-year residents when inserting radial artery using the traditional palpation technique.[10] They hypothesized that traditional palpation skill might decrease as operators prefer to perform ultrasound-guided cannulation. One drawback noted was the increased time taken in preparation as the probe needs to cover in the sterile cover, thus increasing the waiting time for starting the procedure.

  Conclusions Top

In our experience, we found that using ultrasound was beneficial in terms of higher chances of first-attempt success, lesser time for cannulation, lesser time taken, and more objective training benefit for pediatric radial artery cannulation. We suggest routine use of ultrasound for the radial arterial cannulation in pediatric patients. Emphasis should be given on training on the use of ultrasound by residents and other practitioners who require the skill of arterial line placement.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Torrey SB, Saladino RA. Arterial puncture and catheterization. In: King C, Henretig FM, editors. Textbook of Pediatric Emergency Procedures. 2nd ed. Philadelphia: Lippincott, Williams & Wilkins; 2008. p. 715.  Back to cited text no. 1
Gravlee GP, Wong AB, Adkins TG, Case LD, Pauca AL. A comparison of radial, brachial, and aortic pressures after cardiopulmonary bypass. J Cardiothorac Anesth 1989;3:20-6.  Back to cited text no. 2
Troianos CA, Hartman GS, Glas KE, Skubas NJ, Eberhardt RT, Walker JD, et al. Guidelines for performing ultrasound guided vascular cannulation: Recommendations of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. J Am Soc Echocardiogr 2011;24:1291-318.  Back to cited text no. 3
Clemmesen L, Knudsen L, Sloth E, Bendtsen T. Dynamic needle tip positioning-ultrasound guidance for peripheral vascular access. A randomized, controlled and blinded study in phantoms performed by ultrasound novices. Ultraschall Med 2012;33:E321-5.  Back to cited text no. 4
AIUM practice guideline for the use of ultrasound to guide vascular access procedures. J Ultrasound Med 2013;32:191-215.  Back to cited text no. 5
American Society of Anesthesiologists Task Force on Central Venous Access, Rupp SM, Apfelbaum JL, Blitt C, Caplan RA, Connis RT, et al. Practice guidelines for central venous access: a report by the American Society of Anesthesiologists Task Force on Central Venous Access. Anesthesiology 2012;116:539-73.  Back to cited text no. 6
National Institute for Clinical Excellence. Guidance on the use of Ultrasound Locating Devices for Placing Central Venous Catheters. Available from: http://www.nice.org.uk/TA49.[Last accessed on 2020 Jul 04].  Back to cited text no. 7
Schwemmer U, Arzet HA, Trautner H, Rauch S, Roewer N, Greim CA. Ultrasound-guided arterial cannulation in infants improves success rate. Eur J Anaesthesiol 2006;23:476-80.  Back to cited text no. 8
Tan TY, Petersen JA, Zhao X, Taylor KL. Randomized controlled trial of ultrasound versus palpation method for arterial cannulation in infants less than 24 months of age. SOJ Anesthesiol Pain Manage 2015;2:1-3.  Back to cited text no. 9
Anantasit N, Cheeptinnakorntaworn P, Khositseth A, Lertbunrian R, Chantra M. Ultrasound versus traditional palpation to guide radial artery cannulation in critically ill children: A randomized trial. J Ultrasound Med 2017;36:2495-501.  Back to cited text no. 10
Ishii S, Shime N, Shibasaki M, Sawa T. Ultrasound-guided radial artery catheterization in infants and small children. Pediatr Crit Care Med 2013;14:471-3.  Back to cited text no. 11
Aouad-Maroun M, Raphael CK, Sayyid SK, Farah F, Akl EA. Ultrasound-guided arterial cannulation for paediatrics. Cochrane Database Syst Rev 2016;9:CD011364.  Back to cited text no. 12
Ganesh A, Kaye R, Cahill AM, Stern W, Pachikara R, Gallagher PR, et al. Evaluation of ultrasound-guided radial artery cannulation in children. Pediatr Crit Care Med 2009;10:45-8.  Back to cited text no. 13
Eisen LA, Minami T, Berger JS, Sekiguchi H, Mayo PH, Narasimhan M. Gender disparity in failure rate for arterial catheter attempts. J Intensive Care Med 2007;22:166-72.  Back to cited text no. 14
Gao YB, Yan JH, Gao FQ, Pan L, Wang XZ, Lv CJ. Effects of ultrasound-guided radial artery catheterization: An updated metaanalysis. Am J Emerg Med 2015;33:50-5.  Back to cited text no. 15
Ueda K, Puangsuvan S, Hove MA, Bayman EO. Ultrasound visual image-guided vs. Doppler auditory-assisted radial artery cannulation in infants and small children by non-expert anaesthesiologists: A randomized prospective study. Br J Anaesth 2013;110:281-6.  Back to cited text no. 16
Takeshita J, Yoshida T, Nakajima Y, Nakayama Y, Nishiyama K, Ito Y, et al. Dynamic needle tip positioning for ultrasound-guided arterial catheterization in infants and small children with deep arteries: A randomized controlled trial. J Cardiothorac Vasc Anesth 2019;33:1919-25.  Back to cited text no. 17
Schindler E, Kowald B, Suess H, Niehaus-Borquez B, Tausch B, Brecher A. Catheterization of the radial or brachial artery in neonates and infants. Paediatr Anaesth 2005;15:677-82.  Back to cited text no. 18
Berk D, Gurkan Y, Kus A, Ulugol H, Solak M, Toker K. Ultrasound-guided radial arterial cannulation: Long axis/in-plane versus short axis/out-of-plane approaches? J Clin Monit Comput 2013;27:319-24.  Back to cited text no. 19
Tangwiwat S, Pankla W, Rushatamukayanunt P, Waitayawinyu P, Soontrakom T, Jirakulsawat A. Comparing the success rate of radial artery cannulation under ultrasound guidance and palpation technique in adults. J Med Assoc Thai 2016;99:505-10.  Back to cited text no. 20
Sites BD, Gallagher JD, Cravero J, Lundberg J, Blike G. The learning curve associated with a simulated ultrasound-guided interventional task by inexperienced anesthesia residents. Reg Anesth Pain Med 2004;29:544-8.  Back to cited text no. 21
Miller AG, Bardin AJ. Review of ultrasound-guided radial artery catheter placement. Respir Care 2016;61:383-8.  Back to cited text no. 22


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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