Neuromuscular Complications of ICU

05 November 2004

CLASSIFICATION

1.Myopathy

            -ICU myopathy (acute necrotising myopathy, asthma myopathy

            floppy person syndrome)

-Disuse atrophy

            -Steroid myopathy

            -Pyomyositis

2.Neuromuscular junction abnormalities

            -Myasthenia like syndrome

            -Prolonged neuromuscular blockade

3.Neuropathy

            -ICU polyneuropathy

            -Acute motor neuropathy (Acute axonal variant of GBS)

            -Nutritional neuropathy (B1, B6, B12, Vitamin E)

4.Polyneuromyopathy

5.Others: Hopkins syndrome

MYOPATHY

Disuse atrophy

Increased catabolism, immobility & especially neuromuscular blockers contributory factors.

Common baseline condition upon which other processes (myopathy, neuropathy) are superimposed.

Muscle biopsy: uniform reduction in fibre size without patchy necrosis, Type IIB muscle atrophy nonspecific.

ICU Myopathy

Spectrum:         ICU (cachectic) myopathy

                        Myopathy with selective loss of myosin filaments

Acute necrotising myopathy / Panfascicular muscle necrosis

Quadriparesis

Facial, ocular and respiratory muscles generally spared.

36% intubated asthmatic patients

76% patients with CK>200

Risk factors:

Conditions:       Sepsis

Respiratory disease

Multiorgan failure

Acidosis

Lung > liver > renal transplant

Steroids

Gentamycin

Inotropes (B₂ agonists): ventolin, adrenaline

Neuromuscular blockers

LP if concerned re possibility of Guillain Barre Syndrome

EMG: polyphasic, low amplitude recruitment.

Biopsy: loss of thick myosin filaments, necrosis.            

(Panfascicular muscle necrosis: Sudden, generalised weakness of

muscles accompanied by markedly increased CK, sometimes myoglobinuria.)

MANAGEMENT

1.      Steroids: lowest dose possible for primary disease.

Rapid tapering

2.      Neuromuscular blockers: Intermittent bolus preferred over continuous as

lower total dosage.

Avoid vecuronium & pancuronium as unpredictable prolonged activity of drug or its metabolite.

Atracurium preferred as nonorgan dependent metabolic pathway.

3.      B2 agonist: infuse at lowest dose possible.

    Regularly measure blood & lactate levels.

4.      Metabolic control: Treat fever

  Correct hypoalbuminemia, hyperglycemia, hypophosphatemia, hypokalemia, hypermagnesemia, hypercapneic acidosis.