Annals of Cardiac Anaesthesia Annals of Cardiac Anaesthesia Annals of Cardiac Anaesthesia
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LETTER TO EDITOR Table of Contents   
Year : 2009  |  Volume : 12  |  Issue : 2  |  Page : 169-170
A practical tip: Rings of blood for successful radial artery cannulation

Department of Anaesthesia and Intensive Care, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012, India

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Date of Web Publication21-Jul-2009

How to cite this article:
Arya VK, Subramanyam R. A practical tip: Rings of blood for successful radial artery cannulation. Ann Card Anaesth 2009;12:169-70

How to cite this URL:
Arya VK, Subramanyam R. A practical tip: Rings of blood for successful radial artery cannulation. Ann Card Anaesth [serial online] 2009 [cited 2022 Dec 8];12:169-70. Available from:

The Editor,

Radial arterial cannulation is commonly performed over the guide wire or the needle technique. [1] Failure to recognize that needle is the leading edge of needle-catheter assembly is responsible for most of the failures in later technique. [2] Moreover, a small tissue tag blocking the metallic needle tip may cause difficulty recognizing arterial puncture. We describe a novel way to overcome these problems.

The radial artery is entered over the palpated pulse with arterial cannula as per standard description. [1] Once pulsatile blood flash appears in the metallic needle hub, its angle is reduced and the needle-catheter assembly is further advanced few millimeters to ensure catheter entry into the arterial lumen. Thereafter, the metallic needle is withdrawn few millimeters while maintaining the outer catheter position which creates a little space between them. If there is appearance of a blood-flash in this space [Figure 1], only then catheter can be easily advanced into the arterial lumen over the metallic needle as this ensures that the tip of catheter is within the arterial lumen and the leading edge.

In case, there is no appearance of blood-flash in the needle hub at beginning, uncertainty exists as to whether artery has been punctured or not. We found that this quandary can be solved by pulling out the metallic needle until its tip of approximately 0.5-1 cm can be seen through the catheter before the skin puncture site. If artery has been counter-punctured, multiple blood rings or cylindrical columns will be formed along the catheter wall depending on the quantity of blood smearing receding edge of metallic needle tip due to surface tension property of liquids [Figure 2]. Then, the needle-catheter assembly should be very gradually withdrawn and the re-entry of catheter tip into the arterial lumen can be anticipated by carefully looking at these blood rings or columns, which start moving slowly towards the hub end when the catheter tip is about to re-enter the arterial lumen. This important observation helps the clinician to be careful at this point and a slow, steady withdrawal can be performed not to overshoot the withdrawal process. Throughout this process, the stopper closing the metallic needle is kept in such a way that its hub is not opened to atmosphere. Once blood-splash is apparent between metallic needle and outer catheter, the catheter can be advanced successfully into the arterial lumen over the metallic needle. However, golden rule of holding back whenever any resistance is encountered during advancing catheter is to be followed at every step.

This technique is equally applicable in pediatric patients using 22G and 24G cannulae. When this technique was taught to anesthesiologists in our institution who admitted facing difficulties in arterial cannulation, their success rate improved from 60% to 90%. However, this cannot be used with opaque arterial catheters and is not required in all cases or when ultrasound is used for arterial cannulation which eliminates these problems.

   References Top

1.Tegtmeyer K, Brady G, Lai S, Hodo R, Braner D. Videos in Clinical Medicine. Placement of an arterial line. N Engl J Med 2006;354:e13.  Back to cited text no. 1    
2.Mark JB, Slaughter TF. Cardiovascular monitoring. In: Miller RD, Fleisher LA, Johns RA, Savarese JJ, Wiener-Kronish JP, Young WL (eds). Miller's Anesthesia, Sixth edition, Churchill Livingstone: Philadelphia; 2005. p. 1265-362.  Back to cited text no. 2    

Correspondence Address:
Virendra Kumar Arya
Department of Anaesthesia and Intensive Care, PGIMER, Chandigarh - 160 012
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-9784.53432

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  [Figure 1], [Figure 2]