If Guillain Barre syndrome isnotthe most likely diagnosis:

Depending on symptoms consider brain or spinal pathology (particularly if a sensory level, retained reflexes or bladder/bowel involvement) neuromuscular or muscular cause of weakness.
In addition there are other causes of neuropathy.

If Guillain Barre syndromeisthe most likely diagnosis:

Refer to neurology and carry out the treatment plan under management

If there are problems with breathing, swallow or autonomic dysfunction a referral to medical high dependency should be sought (and ITU if appropriate.)

Assess breathing

• Is the patient breathless lying flat?
• Is their chest wall moving normally?
• Check FVC
  • Iflow:
    • check arterial blood gas (type 2 respiratory failure)
    • check 4 hourly if there is 
      •  a downward trend
      • FVC below 20ml/kg
      • type 2 respiratory failure on Arterial blood gas (ABG)
    • then call ITU for assessment. Invasive ventilation rather than non invasive ventilation is advised.
  • Ifnot low:
    •  then observe and repeat FVC if it is felt that respiratory muscle weakness developing.Those with rapid disease progression, bulbar symptoms, facial weakness and dysautonomia are at particular risk
• Abnormal respiratory rate & oxygen saturation are a late sign of respiratory failure

Autonomic dysfunction

Can occur but it is uncommonly a significant issue. However be aware that patients can have:

• Labile blood pressure
• Tachycardia, bradycardia or arrhythmia (rarely sudden death)
• Urinary retention (if this is the case ensure there is no cord lesion)
• Diarrhoea or constipation

Assess swallow

• Has patient been choking on solids or fluids?
• Is their voice slurred?
• Do they have respiratory failure?

If yes- Speech and Language Therapy (SALT) referral and consider Nasogastric (NG) feeding
If no- observe

Consider IV immunoglobulin (IVIg)

If IVIg is unavailable or contraindicated then plasma exchange is just as effective.
If severe symptoms - patient unable to walk unaided, respiratory or bulbar impairment. Caution required if symptoms mild, patient at high risk of thrombotic disease or kidney injury as risks may outweigh benefits.
Note IVIg is a blood product with theoretical risk of blood borne viruses.

Check immunoglobulin levels as IgA deficiency increases risk of a severe reaction to IVIg but don't delay treatment for result if rapidly progressing.

• Dose is 0.4g/kg per day for 5 days. Eg for 75kg person the dose would be 30g per day for 5 days. See formulary
• Daily renal function and full blood count (FBC)
• Prophylactic LMWH required