2. Antecubital Fossa + Intraarterial injection

Question 1

The anatomy

Borders

Answer 1

triangular intermuscular depression on the anterior surface of the elbow joint

base of the triangle is formed by the line which joins the medial and lateral
epicondyles of the humerus

The lateral side of the triangle is formed by the medial edge of the brachioradialis
muscle, while the medial side is formed by the lateral border of the pronator teres

The floor consists of the brachialis and supinator muscles.

The roof (from above down) comprises skin, subcutaneous tissue and the deep fascia,

which includes the bicipital aponeurosis.

Question 2

Anatomy contents

Answer 2

Within the fossa lie the tendon of the biceps muscle and the terminal part of the
brachial artery, which lies in the centre of the fossa prior to its division into the radial
and ulnar arteries opposite the neck of the radius. It also contains the associated veins
and the median and radial nerves.

Question 3

The anatomy of the superficial veins varies greatly, but that of a typical subject can be
described as follows.

Answer 3

Cephalic vein: this drains the radial side of the forearm, and ascends over the
lateral side of the fossa to lie in a groove along the lateral edge of the biceps
join the axillary vein @ pec major

Basilic vein: this drains the ulnar side of the forearm and rises along the medial
border of biceps to pierce the deep fascia in the middle upper arm before going on
to form the axillary vein.

Median cubital vein: this originates from the cephalic vein distal to the lateral
epicondyle, and then runs upwards and medially across the antecubital fossa to
join the basilic vein above the elbow.

Question 4

Hazards in ACF

Answer 4

One potential hazard is inadvertent puncture or injection
into the brachial artery. The danger of this happening is lessened by the presence
of the bicipital aponeurosis, which is an extension of the medial lower border of
the muscle and tendon of biceps.

The lateral cutaneous nerve of the forearm crosses the fascia of the roof of the fossa
and, although it lies deep to the cephalic vein, may still be vulnerable to damage from
a needle or cannula

Long lines can be inserted via the antecubital veins, which offer a safer route to the
central veins. Although cannulation at the elbow may be simple, the acute curve at
the clavipectoral fascia may prevent a long venous catheter from gaining access to the
central venous circulation.

Question 5

IA injection

Answer 5

intra-arterial catheter is mistaken for a venous cannula, when there is anomalous vascular anatomy such as an aberrant
radial artery that can be mistaken for the cephalic vein at the wrist or when the
arterial pulsation is so feeble in a hypotensive patient that the vessel is thought to be a
vein.

the awake patient, severe pain in the hand
is a cardinal feature. In the anaesthetized or sedated patient, there may be ischaemic

colour changes in the distal limb which, because of arterial spasm, may be pale,
mottled or cyanosed. Thrombosis may follow. The degree of damage depends on the
substance injected.

Question 6

Damage

Answer 6

Thiopental causes substantial damage because at body pH it
precipitates into crystals which occlude small arterial vessels and provoke intense
vasospasm mediated via local noradrenaline release. In contrast, propofol does not
cause the same problems and is relatively innocuous in comparison. Any such
injection, however, should be treated as for the worst-case scenario, because clinical
experience of intra-arterial injection of many drugs is limited.

Question 7

Management

Answer 7

arterial thrombosis and extremity ischaemia puts tissue at risk of
necrosis, and so anti-coagulation is an important priority. Intravenous heparin
500–1,000 units would be a typical initial dose

following which warm NaCl 0.9%
can be infused in an attempt to dilute whatever substance has been injected into the
artery. Arterial spasm can be treated with papaverine 40–80 mg

Dexamethasone 8 mg given immediately may reduce arterial oedema. Perfusion
can be enhanced by sympatholysis, either by a stellate ganglion block (which is quick
to perform) or via a brachial plexus block using a catheter technique to provide
continuous analgesia.

Maintenance anticoagulation is recommended for up to 14
days, and hyperbaric oxygen has also been suggested as a means of minimizing final
ischaemic damage.