5 UPPER LIMB


Upper Limb


5


Structures



  • Antecubital fossa

Circulation



  • Arterial supply
  • Venous drainage

Nervous System



  • Dermatomes and peripheral nerves
  • Brachial plexus
  • Blocks

    • Interscalene block
    • Supra and infraclavicular block
    • Axillary block
    • Median, radial and ulnar nerve blocks

Structures



  • Antecubital fossa

Antecubital Fossa


The cubital (antecubital) fossa is a triangular depression anterior to the elbow joint.


Boundaries



  • Lateral – medial border of brachioradialis muscle
  • Medial – lateral border of pronator teres muscle
  • Base – imaginary horizontal line between the medial and lateral epicondyles of the humerus
  • Apex – meeting point of the medial and lateral borders (brachioradialis overlaps with pronator teres)
  • Floor – brachialis in the upper part and supinator in the lower part of the fossa
  • Roof – superficial to deep – skin, superficial fascia and deep fascia which is reinforced by the bicipital aponeurosis

Contents



  • Biceps tendon
  • Brachial artery
  • Median and radial nerves
  • Median cubital, cephalic and basilic veins (considered to be superficial to the fossa)

The contents of cubital fossa from the medial to lateral side are easily recalled by the mnemonic MBBS (Figures 5.1 and 5.2).

Figure 5.1 Anterior cubital fossa – superficial structures.
Figure 5.2 Anterior cubital fossa – deep structures.

(M = Median nerve, B = Brachial artery, B = Biceps tendon, S = Superficial radial nerve)


Describe the course of brachial artery in the antecubital fossa.


The brachial artery normally bifurcates into radial and ulnar arteries in the apex of the fossa, although this bifurcation may occur much higher in the arm due to anatomical variation.


Which vein would you choose for the insertion of a long line at the antecubital fossa? Where might the line ‘stick’ and how would you negotiate it?


When placing a long line, the two main veins available in the antecubital fossa are the basilic and cephalic veins. The more medial basilic vein has a smoother and direct route to the subclavian vein. The lateral cephalic vein turns more sharply and passes through the clavipectoral fascia with valves present at its termination. These factors increase the risk of the long line not advancing into the subclavian vein when using the cephalic vein. If problems occur with advancing the line, abducting the arm to help straighten out its path might be useful. Flushing the line with saline can also help to advance a line through a valve that may be obstructing its passage.


Bibliography



  1. Sinnatamby, C. S. (2011). Last’s Anatomy, International Edition: Regional and Applied. Elsevier Health Sciences.

Circulation



  • Arterial supply
  • Venous drainage

Arterial Supply of Upper Limb


Can you describe the arterial supply to the upper limb, starting at the aorta?


The subclavian artery originates from the aorta on the left and the brachiocephalic artery on the right. The subclavian artery becomes the axillary artery which then continues as the brachial artery. The brachial artery divides into the radial and ulnar artery at the antecubital fossa between the two heads of the biceps (Figure 5.3 and Table 5.1).

Figure 5.3 Arterial supply – upper limb.

Table 5.1 Arterial Supply of Upper Limb




























Axillary artery


Course: formed at the lateral border of the first rib as a continuation of subclavian artery. It is deep to the pectoralis minor and has the cords of brachial plexus around it. It continues as the brachial artery at the lower border of the teres major muscle.


Supply: shoulder, scapula, axilla, lateral thoracic wall and associated muscles


Brachial artery


Course: begins at the lateral border of axilla and runs medial to the biceps muscle towards the antecubital fossa where it bifurcates into the terminal branches – radial and ulnar arteries


Supply: humerus, elbow and muscles of the arm


Radial artery


Course: descends from the antecubital fossa to the wrist along the lateral side of the forearm between the flexor carpi radialis and the brachialis. It crosses the anatomical snuff box on the dorsal aspect and enters the palm of the hand terminating as the deep palmar arch.


Supply: elbow, muscles of the forearm and hand


Ulnar artery


Course: the ulnar artery descends along the medial side of the forearm alongside the ulnar nerve which lies lateral to it. It travels above the flexor retinaculum at the wrist and sends a branch to the deep palmar arch and terminates as the superficial palmar arch.


Supply: elbow, muscles of the forearm and hand


What are the indications for an arterial cannula?


Blood pressure monitoring



  • Patients with haemodynamic instability (critically ill or undergoing major surgery)
  • Patients requiring vasoactive drugs
  • Patients with burns, arrhythmia and obesity causing inaccurate non-invasive blood pressure monitoring

Blood sampling



  • Frequent blood gas measurements in intensive care patients
  • Regular electrolyte monitoring and in patients with difficult venous access

Interventional procedure



  • Endovascular procedures, coronary angiography, intra-aortic balloon insertion
  • Arterial embolisation

Continuous cardiac output monitoring



  • In critically ill patients
  • In major surgery, to optimise fluid therapy

What might the contraindications be?


Absolute contraindications



  • Absence of collateral circulation (e.g. abnormal modified Allen’s test)
  • Vasculitis – Raynaud’s disease, Buerger’s disease
  • Local vessel pathology – distorted anatomy, aneurysm, stent or vascular graft, arteriovenous malformation or fistula

Relative contraindications



  • Severe peripheral vascular disease
  • Recent use of thrombolytic agents
  • Severe coagulopathy

Which sites in the upper limb do you use for arterial cannulation? What are the site-specific disadvantages?


The radial artery is commonly used as it has a fairly reliable anatomy, is easily palpated and visible with ultrasound guidance. However, it is more prone to occlusion and haematoma formation.


The brachial or axillary artery is often used in paediatric/neonatal ICU but there is significant risk of distal ischaemia and compartment syndrome if there is an arterial occlusion due to the absence of collateral circulation.


The ulnar artery is not routinely used in anaesthetics and there is a risk of ulnar nerve injury due to its close proximity.


How would you site a radial arterial cannula?



  • Preprocedure ultrasound is useful to identify the course, presence of tortuosity and atheroma.
  • Aseptic precautions
  • Cannulation can be done using either ‘over the needle’ or ‘over the wire’ technique using modified Seldinger technique
  • Ensuring connecting line is flushed to prevent accidental air embolus
  • Securing and labelling the line once inserted to prevent accidental use of the line to administer drugs

What are the possible complications?



  • Pain and swelling
  • Accidental dislodgement
  • Thrombotic complications with cerebral embolisation
  • Nerve damage
  • Limb ischemia
  • Haematoma, haemorrhage
  • Infection
  • Formation of pseudoaneurysm and AV fistula

What is Allen’s test? How is it performed?


Allen’s test is a non-invasive evaluation of the arterial patency of the hand which assesses the collateral arterial blood flow. It is done prior to any radial arterial intervention (radial artery harvesting for coronary artery bypass grafting or for forearm flap elevation) or diagnostic work up for thoracic outlet syndrome.


The aim is to check the adequacy of blood flow from the ulnar artery in the event of radial artery occlusion following the procedure.


The original Allen’s test tests both hands at the same time. A modified Allen’s test is currently used which tests one hand at a time.



  1. 1. Elevate the hand and make a tight fist for 30 seconds
  2. 2. Occlude the ulnar and radial arteries
  3. 3. Unclench the fist which should appear pale
  4. 4. Release the ulnar pressure while maintaining radial pressure
  5. 5. Note the time to reperfusion

In a negative (normal) Allen’s test, the hand will flush in 5–15 seconds indicating that the ulnar artery has a good flow.


In a positive (abnormal, positive = persistent pallor) Allen’s test, the time to reperfusion is >15 seconds suggesting that the ulnar circulation is inadequate, in which case, the radial artery should not be cannulated.


What is Volkmann’s ischaemic contracture?


The permanent contraction of the flexor compartment at the level of the wrist due to obstruction of the brachial artery is called Volkmann’s ischaemic contracture. The claw-like deformity occurs due to ischaemia and necrosis of the flexor digitorum profundus and the flexor pollicis longus.


Causes include supracondylar fractures, prolonged upper arm tourniquet time, compression from a plaster cast, compartment syndrome and accidental intra-arterial injection of drugs.


What is the management of inadvertent intra-arterial injection?


Intra-arterial injection of drugs may cause acute, severe extremity ischaemia and gangrene and the main priority is to maintain distal perfusion.


The drugs which cause the most severe ischaemia and tissue death are barbiturates, ketamine and phenytoin, whilst propofol, atracurium, rocuronium and amiodarone can also cause ischaemia.


The steps in the pathophysiology are arterial spasm, direct tissue destruction by the drug and subsequent chemical arteritis leading to endothelial destruction. With certain drugs such as thiopentone, precipitation and crystal formation within the distal microcirculation lead to ischaemia and thrombosis.


Management


General measures



  • Assessment of extent of the injury and early plastic surgery advice
  • Elevation of affected limb to improve venous and lymphatic drainage
  • Good analgesia
  • Anticoagulation with heparin to limit the extent of the ischaemia as thrombosis is ultimately the cause of the tissue injury

Specific measures



  • Local anaesthetic injection
  • Intra-arterial injection of lignocaine through the implicated cannula may be useful in preventing reflex vasospasm. But this can cause further damage and compromise the perfusion to the affected limb.
  • Sympatholysis
  • Stellate ganglion blocks and lower-extremity sympathetic blocks can produce arterial and venous vasodilatation which can also be a good mode of analgesia but should be done after risk-benefit analysis.
  • Other drugs
  • Calcium channel blockers, thromboxane inhibitors (aspirin and methylprednisolone), prostacyclin analogues, intra-arterial papaverine have been used for their vasodilatory and platelet-inhibiting properties to varying success.

Venous Drainage of Upper Limb


The venous drainage of the upper limb can be divided into the superficial and the deep system. The superficial venous system lies in the subcutaneous tissue and drains into the deep venous system via perforating veins.


Superficial venous system



  • The dorsum of the hand displays the dorsal venous network which drain into the cephalic and basilic veins on the lateral and medial side, respectively.
  • The cephalic vein ascends on the lateral side of the forearm and arm and it passes through the deltopectoral groove in the shoulder before emptying into the axillary vein.
  • The basilic vein runs posteromedially to pass anterior to the medial epicondyle of the humerus. In the arm, it pierces the brachial fascia and joins the paired deep brachial veins to form the axillary vein.
  • The median cubital vein connects the cephalic and basilic veins anterior to the cubital fossa.

Deep venous system



  • The deep veins of the upper limb lie underneath the deep fascia. Distally, paired veins lie on either side of the artery but as they continue proximally, the paired vessels merge to form a single vein.
  • The axillary vein drains the shoulder, arm, forearm, hand and lateral chest wall.
  • The subclavian vein, the continuation of the axillary vein, also receives the venous drainage from the scapular region and joins the internal jugular vein to ultimately form the brachiocephalic vein (Figure 5.4).
Figure 5.4 Venous drainage – upper limb.

When attempting venepuncture at the antecubital fossa, which structure in particular provides a degree of protection to the brachial artery?


The bicipital aponeurosis separates the brachial artery (which lies beneath the aponeurosis) from median cubital vein thereby preventing inadvertent arterial puncture during median cubital vein cannulation.


Which superficial nerves are at risk during attempted venous cannulation at the elbow?


Medial, lateral and posterior cutaneous nerves of the forearm.


How can the veins of the upper limb be used to provide central venous access?


Peripherally inserted central catheters (PICC) can be inserted into the upper limb using the Seldinger technique via a needle. The catheter passes through the skin and into the superior vena cava. It can be placed under ultrasound guidance or with a contrast venogram. It is an excellent method of providing medium-term venous access (e.g. feeding lines in paediatrics, long-term intravenous antibiotics).


Bibliography



  1. Gilroy, A. M., Voll, M. M., & Wesker, K. (2017). Anatomy: An Essential Textbook. New York, NY: Thieme Medical Publishers, Inc.
  2. Irwin, R. S., & Rippe, J. M. (2011). Irwin and Rippes Intensive Care Medicine. Philadelphia, PA: Wolters Kluwer/Lippincott Williams & Wilkins Health.
  3. Lake, C., & Beecroft, C. L. (2010). Extravasation injuries and accidental intra-arterial injection. Continuing Education in Anaesthesia, Critical Care & Pain, 10(4), 109–113.

Nervous System



  • Dermatomes and nerve distribution
  • Brachial plexus
  • Blocks

    • Interscalene block
    • Supra and infraclavicular block
    • Axillary block
    • Median, radial and ulnar nerve blocks

The upper limb is divided into the shoulder, arm (between shoulder and elbow), forearm (between elbow and wrist) and hand. The axilla, cubital fossa and carpal tunnel are important areas of transition in the upper limb.


Dermatomes and Peripheral Nerve Distribution


Figures 5.5 and 5.6 show the dermatomal and peripheral nerve distribution of the anterior and posterior aspects of the upper limb.


What movements are provided by the myotomes of the upper limb?



  • C5 – abduction of the arm at the glenohumeral joint
  • C6 – flexion of the forearm at the elbow joint
  • C7 – extension of the arm at the elbow joint
  • C8 – flexion of the fingers
  • T1 – abduction and adduction of the index, middle and ring fingers
Figure 5.5 Dermatomes and peripheral nerves – anterior.
Figure 5.6 Dermatomes and peripheral nerves – posterior.

Brachial Plexus


A complex neural network in the neck and axilla that starts from the intervertebral foramina, passes between scalenus anterior and medius, into the posterior triangle of the neck, behind the clavicle, over the first rib, posterolateral to the subclavian artery and into the axilla. The major nerves of the brachial plexus carry motor and sensory function and it is important to note that the sensory distribution from the peripheral nerves is different from the dermatomes (Table 5.2).


Table 5.2 Functional Importance of Brachial Plexus










Sensory innervation of the upper limb and most of the axilla – except for an area in the medial upper arm supplied by the intercostobrachial nerve. This is often the origin of tourniquet pain.


Motor innervation to the upper limb and shoulder girdle – except for trapezius, which is innervated by the 11th cranial nerve


Autonomic innervation to the upper limb, by communicating with the stellate ganglion at T1


Course of the brachial plexus through the neck, demonstrating its relations to the scalene muscles, subclavian artery and clavicle (Figure 5.7).

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Nov 27, 2021 | Posted by in ANESTHESIA | Comments Off on 5 UPPER LIMB
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