Lesson-Infraclavicular

13 – Infraclavicular block: Point of injection of local anaesthetic

In the infraclavicular block the local anaesthetic should be injected periarterially in the seven o’clock position (seeing the axillary artery as a clock face)

However, it is often necessary to reposition the needle tip in order to inject local anaesthetic periarterially from the two o’clock position around the artery to the ten o’clock position

Click on the VIDEO CLIP button to view the video

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Local anaesthetic is injected periarterially. lateral fascicle (LF); medial fascicle (MF); posterior fascicle (PF); axillary artery (A); local anaesthetic; (LA); minor pectoral muscle (MiP)

14 – The infraclavicular block with repositioning of the needle tip

Repositioning of the needle tip is oftentimes necessary in order to cover all three cords around the axillary artery from two o’clock to ten o’clock

Care should be taken not to pierce the axillary vein

Click on the VIDEO CLIP button to view the video

In the video: Notice that local anaesthetic is injected on the wrong side of the clavipectoral fascia which has to be penetrated by the needle before local anaesthetic spreads appropriately around the medial cord

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The video shows repositioning of the needle tip during an infraclavicular block
First, local anaesthetic is injected around the lateral cord in the ten o’clock position
Then, the needle is relocated in front of the axillary artery in order to reach the medial cord

15 – Injection of local anaesthetic around the medial cord

The medial cord is located between the axillary artery and vein around the two o’clock position of the artery

The local anaesthetic does not always spread around the artery to the two o’clock position from a seven o’clock point of injection

In that case the needle tip should be repositioned in front of the axillary artery to the interspace between the axillary artery and vein and local anaesthetic should be injected periarterially

Click on the VIDEO CLIP button to view the video

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Periarterial injection of local anaesthetic between the axillary artery and vein in order to cover the medial cord of the brachial plexus
MaP = major pectoral muscle; MiP = minor pectoral muscle; A = axillary artery; V = axillary vein

16 – Colour Doppler

Colour Doppler can be used to visualise the proxy marker – the axillary artery – and blood vessels that you do not want to perforate with the needle

It is also possible to use colour Doppler to visualise the injection of local anaesthetic

In that case it is an advantage to lower the PRF (Pulse Repetition Frequency) in order to enhance the visibility of the injectate

Click on the VIDEO CLIP button to view the video

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The video shows the pulsating colour Doppler signal from the axillary artery

17 – Avoid injecting air perineurally

Before inserting the needle through the skin, the hose and the needle should be filled with saline or local anaesthetic

Just after insertion of the needle 1/2 ml of fluid should be flushed through the hose and needle to make sure that no air is contained in the “system”

Click on the VIDEO CLIP button to view the video

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The video shows the blurring effect of injected air during the performance of an infraclavicular nerve block
A = axillary artery; MaP = major pectoral muscle; MiP = minor pectoral muscle

12 – How to perform the infraclavicular brachial plexus block

Select a linear high-frequency probe. Adjust gain, focus and depth 3-4 cm

Turn the orientation mark on the probe cranially. Place the probe below the clavicle, medial to the coracoid process in the parasagittal plane

Locate the black, pulsatile axillary artery (AA) and align it to the centre of the monitor. Seeing AA as a clock face the lateral cord is located at nine o’clock, the posterior cord at six o’clock and the medial cord at two o’clock. Often the cords are not sonographically visible

Insert the needle below the clavicle and advance it in-plane aiming periarterially at seven o’clock. Empty the needle of air by injecting 1/2 mL local anaesthetic subcutaneously

Avoid piercing any vessels or nerves

The endpoint of injection is periarterially from two o’clock to ten o’clock. Reposition the needle tip as necessary to reach the endpoint

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(A) the infraclavicular approach

(B) Look for the axillary artery (A); lateral cord (L); medial cord (M); posterior cord (P). Anterior (ant), posterior (post)

8 – Anatomy of the brachial plexus in the infraclavicular region

The infraclavicular block anaesthetizes the brachial plexus inside the axilla

The brachial plexus in the infraclavicular region consists of three cords (syn: fascicles): the lateral, the posterior, and the medial cord

They run in close relationship to the axillary artery

That is exploited for the purpose of the infraclavicular brachial plexus block

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The picture shows the axilla after removal of the anterior wall of the axilla (the major and minor pectoral muscles)
The three cords of the brachial plexus are named according to their relationship to the middle part of the axillary artery

9 – The intercostobrachial nerve

The brachial plexus innervates the entire upper limb – except part of the skin of the upper half of the medial arm which is innervated by the intercostobrachial nerve

The intercostobrachial nerve is synonymous to the lateral cutaneous branch of the second intercostal nerve

The intercostobrachial nerve joins the medial cutaneous nerve of the arm to supply the skin of the upper half of the medial arm

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The green colour depicts the intercostobrachial nerve which branches off as the lateral cutaneous nerve of the second intercostal nerve
The intercostobrachial nerve is not part of the brachial plexus