Critical Illness Polyneuropathy (CIP)

Original Editor - Matt Ross Top Contributors - Matt Ross, Lucinda hampton, Kim Jackson, Tolulope Adeniji, Adam Vallely Farrell and Karen Wilson

Introduction

Clinicians in Intensive Care Unit

Critical Illness Polyneuropathy (CIP) is the acute or subacute onset of extensive symmetric weakness in critical ill patients , usually with sepsis, respiratory failure, multisystem organ failure, or septic inflammatory response syndrome (SIRS). Clinical presentation includes distal extremity weakness, wasting, and sensory loss, as well as paresthesia and decreased or absent deep tendon reflexes.

Intensive Care Unit Acquired weakness (ICUAW) include 3 subsets:

1. Critical Illness Polyneuropathy (CIP)
2. Critical Illness Myopathy (CIM)
3. Critical Illness Neuromyopathy (CINM).

Pathological Process

The pathophysiology for CIP remains unclear and complex, with human studies highlighting axonal degeneration .

It is hypothesized to be connected to:

• Drug, nutritional, metabolic, and toxic factors
• A long ICU stay
• The number of invasive procedures
• Hyperglycemia
• Decreased albumin level
• The Severity of multisystem organ failure.

With risk factors including a number of the above ie Sepsis; SIRS; Multi Organ Failure (MOF); Female Gender; Duration of Organ Dysfunction; Duration of ICU Stay; Ionotropic Support; Renal Failure; Low Serum Albumin; Hyperglycemia; Neuromuscular Blockades; Corticosteroids

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Clinical Presentation

Visser (2006) reports that the clinical features of CIP typically include:

• Muscle Weakness: Predominantly in the lower extremities. This should be suspected if there is reduced limb movement following a painful stimulus to the distal limb. Flaccid weakness can be observed symmetrically.
• Absent Facial Weakness: Cranial nerves are rarely affected.
• Muscle Wasting: Observed in one third of patients
• Reduced Muscle Reflexes: Reflexes are usually present at the start of the disease, but decrease over time.
• Difficulty in Weaning from Ventilator
• Sensory Loss: Although difficult to assess with a sedated or intubated patient.
• Impaired Consciousness: Suggested of an encephalopathy is also usually present
  

Diagnostic Procedures

ICU unit

Although performed rarely, the gold standard for the diagnosis of critical illness neuropathy remains electrodiagnostic testing. This includes nerve conduction studies and needle electromyography. However while EMG is the best way to of making a diagnosis of CIP, it is challenging to perform a complete study in ICU settings, including electrical interference, anasarca, hypothermia, peripheral edema, or limited patient participation in the exam.

• Currently there are no validated biomarkers available.
• Although not commonly performed, CIP will demonstrate features of denervation and reinnervation with small muscle fibers, fiber-type grouping, and fiber group atrophy with widespread axonal degeneration of both motor and sensory nerves. Muscle biopsy can display thick filament loss which is commonly associated with CIM, with evidence of denervation and reinnervation changes and axonal degeneration associated with CIP.

Differential Diagnosis

• Guillain-barre syndrome (GBS)
• Trauma: A spinal cord or head injury should be ruled should there be muscle weakness following a traumatic injury, as spinal shock can result in muscle weakness and areflexia
• Neuromuscular blockades: Prolonged neuromuscular blockades can result in the development of acute quadriplegic myopathy, and can be identified by repetitive nerve stimulation. This can be reversed by giving cholinesterase inhibitors. Sensation and reflexes are usually spared
• Critical illness myopathy (CIM): CIP and CIM usually co-exist during ICUAW,

Coincident illness include:

• Eaton-Lambert Syndrome: A rare autoimmune disorder characterised by muscle weakness of the limbs
• Myasthenia Gravis: A rare, long term illness that commonly affects the muscles of the eyes and eyelids, facial expressions, chewing, swallowing and speaking and other parts of the body.
• Vasculitis: Inflammation of the blood vessels.

Outcome Measures

The Oxford Muscle Grading System assists with the diagnosis of CIP. Bi-lateral testing of shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and dorsiflexion of the ankle will create a total score of 60. 48/60 designates ICUAW or significant weakness, and an MRC score below 36/48 indicates severe weakness

Management

Semirecumbent positioning

Upon diagnosis of CIP, the interprofessional team including physicians, physical therapists, occupational therapists, speech therapists, nutritionists, social workers, and case managers need to work together to coordinate early mobilization and aggressive multifaceted rehabilitation.

Medical management

1. Glycemic Control: Studies have shown that intensive insulin therapy for hyperglycemia lowered the risk of critical illness polyneuropathy and myopathy, and decreased time on ventilatory support, the duration of intensive care unit stay, and the 180-day mortality rate.
2. Optimising Nutrition
3. Treatment of Sepsis: Likely that adequate and early treatment of sepsis reduces the incidence of CIP. Treatment modalities to reduce this risk are centred around the use of semi- recumbent positioning, use of low tidal volume mechanical ventilation, and no or careful use of sedative or neuromuscular-blocking agents. See Sedation in Critically-Ill Patients
4. Neuromuscular blocking agents (NMBA), potent muscle relaxants, block neuromuscular transmission and causes paralysis of the muscle: Multiple studies have shown that there is a correlation between ICUAW and neuromuscular blockade. It is recommend that continuous vigilance is needed when NMBAs are used in critically ill patients, selecting the appropriate NMBA for each individual setting, evidence-based protocols are followed to ensure adequate sedation and analgesia, appropriate equipment for assessing the degree of neuromuscular blockade, and aggressive physical therapy regimens during periods of reduced mobility.

Physiotherapy

Early mobility ICU

Long periods of immobilisation are now being recognised as an important aspect to address when managing CIP.

Performing rehabilitation early on is a key focus in the NICE guidelines (2009 guidelines, checked December 2022, no new evidence that affects the recommendations in this guideline.).

Early mobilisation facilitates and improves long-term recovery and functional independence of patients, shortening the duration of ventilation and hospitalisation. Treatment should be tailored to the clinical presentation of the patient and could include:

• Passive range of movement to maintain muscle length and prevent contractures due to prolonged bed rest.
• Active/active assisted exercises to improve strength and endurance.
• Positioning in bed to facilitate improved lung function.
• Sitting on edge of bed to facilitate trunk control / balance.
• Sitting out in chair to improve lung function (either via pat slide, hoist, standing hoist or transfers).
• Mobilising to improve lung function, cardiovascular fitness, muscle strength and promote independence.

Take a deeper look by viewing this Early Mobility Assessment for Critically Ill Patients, Early Mobilization in the ICU and Implementing an Early Mobility Programme for Critically Ill Patients

Resources

NICE Guidelines (2009): Rehabilitation following Critical Illness

Cochrane Review: Interventions for preventing critical illness polyneuropathy and critical illness myopathy

The development of a clinical management algorithm for early physical activity and mobilization of critically ill patients: synthesis of evidence and expert opinion and its translation into practice.

Guidelines for the Provision of Intensive Care Services