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Proning patients & avoiding injury to the brachial plexus

Tom Quick FRCS MD

Honorary Associate Professor and Consultant Peripheral Nerve Surgeon.

 

What is the brachial plexus?

The brachial plexus is a group of nerves which control the arm. These nerves come together in the neck as they leave the spine at 5 levels. They come together to form this plexus (interconnected group) of nerves for the arm (brachium). This group of nerves runs from the neck, just behind the collar bone, to the chest, through the armpit to the inner side of the arm and then splitting to its branches in the arm.

 

Brachial_plexus_color.svg

 

The nerves bring movement to the shoulder, elbow forearm wrist and hand by controlling the muscles and allows feeling sensation pain. It also controls sweating and the function of  skin and the growth of the arm in children. 

Injury can lead to pain, paralysis or weakness, tingling or numbness.

Nerve injury can be temporary (a conduction block) which will resolve spontaneous over a few days to 3 months. Severe cases where compression of traction in an unconscious patient can provide long term morbidity and may require surgery to attain optimal outcome. Monitoring and documenting change over time is important and neurophysiology assessment can often provide further information.

Painful palsies (paralysis of a muscle with pain in that same nerve territory) must be treated as an EMERGENCY and referred to a team specialised in the assessment and treatment of such problems.

What is ‘proning’

‘Proning’ is a process of turning a patient on to their front or ‘prone’. This allows the way the oxygen and blood mix in the lungs to be improved when the lungs are suffering from inflammation. This is performed  in patients who are conscious and breathing for themselves in this case patients move regularly and respond to pain or numbness when they position themselves. In very unwell, weak or unconscious patients however they are unable to respond to ensure they are not damaged. Thus it is important to take very careful attention to pressure areas where tissue can be damaged and to tension where similarly nerves can be damaged. 

This has also led to the inclusion of prone ventilation in the ARDS guidance published by the Intensive Care Society (ICS) and Faculty of Intensive Care Medicine (FICM). 

Proning; an unconscious patient can result in problems due to unrecognised pressure or stretch 

  • Pressure sores (most cited injury) 
  • Facial / periorbital oedema
  • Ocular injury/corneal abrasions 
  • Brachial plexus injury 

Most of these complications are preventable. We will focus here on the injury to the brachial plexus.

What advice is there no how best to safely prone patients for ventilation?

https://www.ficm.ac.uk/sites/default/files/prone_position_in_adult_critical_care_2019.pdf

Key points regarding brachial plexus prophylactic care

  • Carefully position the arms in the ‘swimmers position’
  • This involves raising one arm on the same side to which the head is facing whilst placing the other arm by the patients side. The shoulder should be abducted to 80° and the elbow flexed 90° on the raised arm
  • The position of both the head and arms should be alternated every two to four hours
  • Pressure areas should be meticulously checked

 

How can the brachial plexus be damaged?

The brachial plexus is made up of interconnecting nerves and these can be damaged by pressure and stretch. Both pressure and stretch can be created when positioning an unconscious patient. Those more at risk are older patients, heavier patients, those with diabetes, and those with predisposing anatomical or physiologic variants.

These mechanisms of injury lead to either a ‘conduction block ‘ of the nerves where they do not die but stop working (anatomically intact, physiologically broken) or to a ‘degenerative injury’ where the nerve cells die back and then try to regrow over time.

 

What else should I think about?

Any unconscious patient should have their joints passively moved and the upper limb can get stiff very quickly.  Each joint has movements which are more challenging to try to recover if they do get stiff-  passive external rotation of the shoulders, flexion/extension of the elbow, Supination/pronation of the forearm, flexion.extension of the wrist. The hand has a typical posture which it adopts in stiffness; so if the hand is not splinted in a position of safe immobilisation (POSI) where the MCPJs are flexed, and the IPJs are extended these movements should be performed regularly and frequently. In the current environment there is a great deal of pressure on medical and paramedical staff so splintage should be considered if regular therapy is not likely to be frequent.

Any splints should be well padded, well fitting and checked regularly. 

In any patient with an isolated nerve injury or wider brachial plexus palsy this is particularly important.

 

How to assess injury to the brachial plexus

The brachial plexus assessment in an unconscious patient is challenging and thus the mainstay is prevention. However on recovering consciousness it is important to pay particular attention to any complaint from the patient of pain or numbness in the limbs. If the patient cannot communicate verbally then check this with a direct yes/no question with the answer sought be non verbal means. 

Check skin colour and pulses first. Any concern call your vascular team.

Ask the patient what the concern is; weakness, pain numbness, tingling or other strange feelings, document where on the limb these are.

Any pain should be investigated- Is it worse on passive stretch? [have a low threshold to call for an assessment for a compartment syndrome as an EMERGENCY from your surgical team]

Neuropathic pain is burning stinging, squeezing pain and should be referred urgently to a nerve surgeon.

Any paralysis with associated neuropathic pain should be referred urgently also.

Painless paralysis which doesn’t resolve with in 2 days following recognition should also be referred.

For more see : here

How to refer?

The Peripheral Nerve Injury unit at the Royal National Orthopaedic hospital is available for advice -contactable on rnoh.nerveinjury@rnoh.nhs.uk or phone 020989095803.

 

©TJQApril2020