Neuromuscular diseases and respiratory failure are common processes encountered in both neurologic and medical intensive care units. Problems can be encountered anywhere along the peripheral nervous system. Neurogenic respiratory failure can be localized to diseases of the motor neuron, peripheral nerve, neuromuscular junction, or muscle.
This chapter provides a broad overview of the clinical presentation of neuromuscular respiratory failure and reviews diagnostic criteria and treatment for specific neuromuscular diseases.
NEUROMUSCULAR RESPIRATORY FAILURE: CLINICAL FEATURES
Patients with neuromuscular respiratory weakness need to be closely followed with pulmonary function tests. These should include at least vital capacities, negative inspiratory forces, and expiratory flow volumes. Part of the need for close monitoring is due to the often unreliability of the clinical exam.
▪The clinical signs and symptoms of patients with neuromuscular failure may differ and can present with varying signs and symptoms of respiratory, bulbar, or appendicular weakness.
▪Patients may complain of dyspnea or a vague sense of uneasiness. Brow sweating is common.
▪In many circumstances a patient with neuromuscular failure will develop the typical signs and symptoms of respiratory difficulties (tachypnea, tachycardia, accessory muscle use, decreased cough, etc.).
A patient with a rapidly ascending paralysis, an acute dysautonomia, or neuromuscular junction inhibition may not be able to manifest the signs and symptoms typically encountered in a patient with impending respiratory arrest secondary to primarily pulmonary processes. Thus a decision on the timing of endotracheal intubation should be based on the decline of pulmonary function tests and not necessarily on the clinical presentation of the patient. In the above circumstances patients may appear well until the need for urgent intubation.