Case of the Month #35: Analgesia for Rib Fractures by Dr Mariam Latif

A Lidocaine 5% topical plaster was prescribed next for Mr M. Though currently possessing a UK Marketing Authorisation for the management of postherpetic neuralgia only, internationally, lidocaine plasters are an established second line treatment for peripheral neuropathic pain³. Increasing opioid analgesia is also an option, however, the side effect profile seem counterintuitive when wanting to rehabilitate patients following their injury. The lidocaine plaster was applied directly to skin over the fracture site on the right thoracic wall. Mr M did feel a slight improvement of his pain but not enough to achieve outcomes required for successful recovery. He was still requiring multiple doses of his PRN oramorph in addition to his regular analgesia of paracetamol, ibuprofen and codeine.
 

Regional Analgesia for Rib Fractures

Mr M was subsequently offered a regional anaesthesia block to help alleviate his pain. Infusion catheters deliver local anaesthetics directly to the affected area, targeting the source of pain more effectively. This localised approach not only reduces the need for systemic opioids but also minimises their potential side effects, such as respiratory depression⁴. Regional blocks are readily offered as part of the rib fracture management pathway at the Trust where Mr M was treated.

Traditionally, epidural analgesia may have been proposed as it is a well-practised procedure with evidence of efficacy that extends to cover rib pain. Meta-analysis has demonstrated that thoracic epidural provides superior analgesia to paravertebral, intercostal block and IV analgesia⁴. However, with recent advances in regional anaesthesia, now an essential element of the 2021 curriculum, delivery of ultrasound-guided regional chest wall blocks should be within the capability of all anaesthetists⁵. Several fascial plane blocks have been described that target the dorsal, lateral and anterior cutaneous nerves of the thorax and abdomen. For the chest wall, the erector spinae plane (ESP) block has been recommended as a ‘Plan A’ block, one of few versatile, high-value yet simple blocks promoted for widespread competence. The paravertebral, serratus anterior plane (SAP) and PECS blocks can be considered as its alternative, albeit more advanced, counterparts targeting that same area⁶. The SAP, for example, may be advantageous in patients unable to sit up or lay lateral as this can be performed in supine position. 

The advantage of the fascial plane blocks is that they are technically easier to perform compared with neuraxial, nerve plexus, and targeted nerve blocks and rely on volume of local anaesthetic spread. Though more evidence is needed, they may be as efficacious as epidurals but associated with lower risk of spinal cord damage, nerve trauma and cardiovascular instability making them the intervention of choice when considering the widespread use of anticoagulants in the population. 

The ESP block was described in 2016 by Forero and colleagues, where local anaesthetic (LA) is deposited deep to the erector spinae muscles and superficial to the transverse processes, i.e. the target plane, by visualising the needle tip onto the transverse process under ultrasound⁷. Here, the LA is near the costotransverse foramina, where both the dorsal and ventral rami of the thoracic spinal nerves originate. Cephalo-caudad LA spread is thought to be facilitated by the thoracolumbar fascia, which extends across the whole of the posterior thorax and abdomen and is continuous with the nuchal fascia in the neck. This explains the significant pain relief felt by Mr M over the right hemithorax after his ESP block⁸.  A catheter was secured in situ to provide continuous LA infusion via an elastomeric pump over the next 3 days and his lidocaine plaster, now contraindicated with a regional block in place, was removed.  Another practical advantage of ESP block is the ability to perform on the ward or ED, in either sitting or lateral position. It has minimal effects on mean arterial pressure and respiratory function, so does not require specialist nursing care to monitor, nor do the pumps that auto-infuse⁸.

• How would you summarise a multimodal management plan for someone like Mr M with rib fractures?

• What other modes of treatment should not be forgotten?