Comparison of ultrasound guided dorsal radial artery cannulation and conventional radial artery cannulation at the volar aspect of wrist: A randomized controlled trial

Arterial cannulation is a commonly performed invasive procedure used in operating room, intensive care unit, emergency department and in cardiac catheterization laboratory. Arterial cannulation allows beat-to-beat blood pressure measurement, blood sampling for blood gas analysis and can be used for guiding fluid therapy in critically ill or surgical patients^{1, 2}. Radial artery, being easily accessible because of its superficial location, is one of the most preferred sites for arterial cannulation and has a low rate of procedural complications from arterial cannulation^{3, 4}. Classically radial artery cannulation is performed by digital palpation method at the volar aspect of the wrist. Complication of radial artery cannulation are bleeding, hematoma formation, infection, arterial thrombosis, pseudo-aneurysm formation, injury to the median nerve etc⁵. Though the complications are uncommon, some of them have serious implications.

Dorsal radial artery cannulation is a relatively less evaluated technique and offers few advantages over classic radial artery cannulation. The dorsal radial artery is located by palpation of the pulse on the dorsum of the hand, between the bases of the first and second metacarpals, in the "anatomical snuffbox." The palmar branch of the radial artery, which contributes to the superficial palmar arch, arises from the radial artery in the volar side of the wrist before entering the anatomical snuffbox. Catheterizing the dorsal radial artery has the advantage of cannulating more distally than with the traditional trans-radial approach, beyond the origin of the palmar branch. Avoiding trauma to this important collateral vessel could reduce the risk of digital ischemia. Moreover, maintaining vessel integrity both during and after cannulation could be advantageous when cannulating a branch located most distally from the aorta. Although the radial artery in the volar area is favored for its superficial location, the dorsal radial artery is also superficially palpable within the anatomical snuffbox. Moreover, whereas the course of the superficial radial artery on the volar side can be altered by even minor changes in wrist positioning, the dorsal radial artery is free from such positional influences. As the dorsal radial artery resides in the anatomical snuffbox, it is firmly positioned between the first dorsal interosseous muscle and extensor carpi radialis longus muscle, so a catheter within this artery will be in a stable position, with minimal risk of kinking or malpositioning, even after abrupt positional changes.

Aims & objectives

In this prospective randomized controlled trial, clinical utility of dorsal radial artery cannulation will be compared with conventional radial artery cannulation at the volar aspect of wrist in terms of:

1.     First attempt success rate (Primary outcome)

2.     Overall success rate of cannulation

3.     Number of attempt of success

4.     Time to cannulate the artery

5.     Time to puncture the artery

6.     Any complications related to the cannulation such as bleeding, thrombosis, hematoma formation etc.

Methods

Study design: Prospective randomized parallel group study

Study setting: Main operation theatre, AIIMS, New Delhi

Study population: Adult patients (aged between 18 to 65 years) of either sex and American Society of Anaesthesiologists physical status I or II undergoing any surgery under general anaesthesia requiring radial arterial cannulation for anaesthesia and perioperative management will be recruited in this study.

Exclusion criteria:

1.     Patients’ refusal to participate in this study

2.     Patients with ASA physical status III or more

3.     Patients with peripheral vascular diseases

4.     Patients with coronary artery diseases

5.     Patients undergoing emergency surgery

Randomization & blinding

Patients will be randomized as per a computer generated random number table in the two following groups:

Group D (n=100): Dorsal radial artery will be cannulated under USG guidance by Seldinger technique

Group W (n=100): Radial artery will be cannulated at the volar aspect of wrist under USG guidance by Seldinger technique.

Patients’ randomization sequence will be kept inside an opaque sealed envelope and will only be handed over to the investigating team after induction of general anaesthesia. The operators who are cannulating radial artery will not be blinded to the technique being followed for obvious reason. All cannulation will be done by either of the two investigators (SM or DKB) to maintain uniformity. Outcome data will be collected the anaesthesiologists who are not member of the investigating team.

Study protocol: Only patients requiring arterial cannulation for anaesthesia and perioperative management will be recruited in this study. All patients will be evaluated on the day before surgery by the anaesthesia team to assess their suitability for recruitment in this study. Preoperative investigations including complete hemogram, serum electrolytes, renal function test will be recorded as per standard Institute protocol. Patients will be premedicated with oral alprazolam 0.25mg and ranitidine 150 mg on the night before surgery. In the operating room, an 18G intravenous cannula will be secured and standard monitoring as American Society of Anesthesiologists’ recommendation will be attached. A thoracic or lumbar epidural catheter will be placed when clinically indicated. General anaesthesia will be induced with intravenous fentanyl 2mcg kg; propofol 2-3 mg kg and tracheal intubation by appropriate size cuffed endotracheal tube will be facilitated by intravenous atracurium 0.5 mg kg. Anaesthesia will be maintained with volatile anaesthetic agent (sevoflurane, isoflurane or desflurane) in air-oxygen (FiO₂=0.5) targeting an end-tidal concentration of 0.8-1.0 of minimum alveolar concentration and muscle relaxation will be achieved by intermittent boluses of short or inter-mediate acting muscle relaxant or their infusion.

After induction of general anesthesia, patients will be randomized in two groups as per randomization number. Site of radial artery cannulation will be decided as per randomization sequence and under all aseptic precautions area of cannulation will be draped. In patients belonging to group D, the dorsal radial artery will be located by palpation of the pulse on the dorsum of the hand, between the bases of the first and second metacarpals, in the "anatomical snuffbox." Then a small foot print linear USG transducer (Snosite^TM L25xp, 13-6 MHz) will be placed over the radial artery in transverse axis. The artery will be located as hyperechoic circular pulsating structure between the two meta-carpal bones and USG transducer will be adjusted to keep the radial artery in the middle of the ultrasound screen. A 20G puncture needle will be used to cannulate the radial artery under ultrasound guidance in short-axis view. Once pulsatile blood flow is noted in the hub of the puncture needle and tip of the needle is visualized inside the radial artery, a J- tipped metallic guide wire of 0.53mm will be inserted in the arterial lumen and puncture needle will be taken out. Next a 20G polyethylene catheter of 20cm length with winged hub will be railroaded over the guide wire and the guide wire will be pulled out once the catheter is inserted. Position of arterial catheter will be confirmed by pulsatile flow of bright red blood in the hub and it will be connected with a pressure monitoring tubing for arterial blood pressure measurement. In patients belonging to the group W, radial artery will be located 2-4cm proximal to the flexor crease of the wrist and the artery will be cannulated in the methods described above.

When cannulation will be failed even after three attempts, patients will be marked as ‘unsuccessful’ and identified as failure of the technique.

Data collection: Following data will be collected unblinded anesthesiologists who are not a part of this study:

1.     Time to cannulate the artery (defined as time to localizing the artery in USG screen to insert the catheter inside the artery)

2.     First attempt success of cannulation

3.     First attempt success of arterial puncture

4.     Number of attempt required for successful cannulation

5.     Number of attempt required for successful arterial puncture

6.     Overall success rate

Sample size estimation and plan for data analysis

With best of our knowledge, no previous study has evaluated dorsal radial artery cannulation till date. To obtain normally distributed data, n=100 patients will be recruited in each group in this study. Demographic data will be expressed as mean ± SD (age, weight, height) or proportion (sex and ASA physical status). Arterial cannulation time will be expressed as median and inter-quartile range.

Review of literature

Radial artery is the most frequently chosen site of arterial cannulation for its superficial location. Arterial cannulation is a safe procedure and most of the complications such as bleeding, arterial spasm, temporary arterial occlusion are minor in nature. However, some serious complications such as digital ischemia due to arterial thrombosis, injury to the median nerve, carpal tunnel syndrome and pseudo-aneurysm are also reported⁵. Amongst this nerve injury and arterial occlusion leading to ischemia are the two most important complications, which can be reduced with dorsal approach of radial artery cannulation. The digital arteries supplying the fingers arise from the superficial palmar arch. The palmar branch of the radial artery, which contributes to the superficial palmar arch, arises from the radial artery in the volar side of the wrist before entering the anatomical snuffbox. Catheterizing the dorsal radial artery has the advantage of cannulating more distally than with the traditional transradial approach, beyond the origin of the palmar branch. Avoiding trauma to this important collateral vessel could reduce the risk of digital ischemia. 

References

1.     Scheer B, Perel A, Pfeiffer UJ. Clinical review: complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine. Crit Care. 2002;6:199-204.

2.     Gu WJ, Wu XD, Wang F, Ma ZL, Gu XP. Ultrasound Guidance Facilitates Radial Artery Catheterization: A Meta-analysis With Trial Sequential Analysis of Randomized Controlled Trials. Chest. 2016;149:166-79.

3.     Brzezinski M, Luisetti T, London MJ. Radial artery cannulation: a comprehensive review of recent anatomic and physiologic investigations. Anesth Analg. 2009;109:1763-1781.

4.     Jolly SS, Yusuf S, Cairns J, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicenter trial. Lancet. 2011;377:1409-1420.

5.     Scheer B, Perel A, Pfeiffer UJ. Clinical review: complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine. Crit Care. 2002;6:199-204.

6.     Choi S, Park JM, Nam SH, Kim EJ. Cannulation of the dorsal radial artery: an underused, yet useful, technique. Korean J Anesthesiol. 2014;67:S11-2.