Ultrasound-guided Block of the Supraclavicular Nerves in Clavicular Fractures

In 2013 Tran and colleagues reported about a controversial knowledge concerning the sensory innervation of the clavicle which may lead to different approaches of regional analgesia (RA) in CF: superficial cervical plexus blocks, interscalene blocks, and combined superficial cervical plexus-interscalene blocks. Since the innervation of the clavicle comes from four nerves (supraclavicular nerves, subclavian nerve, long thoracic nerve and suprascapular nerve) it seams to be quite difficult to guarantee a complete sensible clavicular block for an operation. Nevertheless, few case reports exist, witch describe clavicle operations under RA alone. However, in these cases a considerable amount of local anaesthetics (LA) has been used that it may be assumed that there could have been dangerous side effects.

Valdés-Vilches and Sánchez-del Águila pronounced the importance of the supraclavicular nerves (SCN) in CF. For that reason, our purpose is to determine the effectivity of a single nerve block of SCN in CF in the ED with only 2-3 millilitres of LA. The aim of our study is to investigate the effectiveness of this method in CF to be operated up to 24 hours later. For this purpose, the SCN, which run directly under the skin of the neck, will be located using an ultrasound device (US). Under US-guidance the injection needle approaches the SCN and 2-3 millilitres of LA are injected around the nerves. The pain relief may last 12 up to 24 hours, which bridges the time until the operation (OP).

In order to compare this new procedure, CF-patients will be divided into two groups, of which the control group (20) will be treated with painkillers in the conventional manner and the intervention group (20) will receive the US-guided block of the SCN.

The following medical products and medicaments will be used, which are all already registered and authorised in Switzerland:

• US-machines: Samsung HS60 High-End with linear-probe (array) LA4-18BD; Samsung RS85 Premium Radiology with linear probe LA4-18B.
• Needle: PAJUNK SonoTAP 24 Gauge x 40mm
• LA: 3 ml Bupivacaine 0.5% +75mcg Clonidine as an adjuvant. The LA will be used in accordance with the prescribing information. The dose will be up to 10 fold lower than the usual used dosages in cervical nerve blocks, since with US-guidance there will be an excellent accuracy to approach the desired single nerve.

In the intervention group, the investigators expect a nearly complete pain relief up to the operation than with conventional pain management and a lower rate of side effects than with systemic administration of painkillers.

With the small amount of LA injected, adverse events (AE) are expected very rare. Nevertheless, the puncture in the side of the neck may cause bruises at the site of the injection or uncomfortable, spreading pain. Systemic side effects are unlikely. A well-known and much feared AE of RA of the brachial and cervical plexus is accidental anaesthesia of the phrenic nerve, which runs from the neck to the diaphragm near the four aforementioned nerves. The paralysis of the phrenic nerve by the injected LA can cause breathing difficulties because the diaphragm is the main breathing muscle. Another possible complication is a drop in blood pressure and heart rate, which can result from anaesthesia of the autonomic nerves in the neck. For these reasons, RA of the brachial and cervical plexus should be performed with as little LA as possible. However, if the SCN-block is performed correctly, the LA can neither reach the phrenic nerve nor the vegetative nerves, since the SCN lays outside the prevertebral layer of the deep cervical fascia, where the phrenic and the vegetative nerves lie within.

Preliminary investigations in our ED in the last two years have shown that 2-3 millilitres of LA are too small a quantity of fluid to reach the phrenic nerve or to cause serious systemic side effects through absorption.