Respiratory management in acute neurologic illness.

Abstract

Acute respiratory failure in neurologic critical illness may accelerate rapidly, becoming profound in a matter of minutes. Therefore, assessment and timely management are crucial when one is suddenly faced with a deteriorating patient. When acute respiratory failure is associated with impaired gas exchange, the situation is even more urgent. In our opinion, management of the airway and mechanical ventilation is different in neurologic critical illness for several reasons. First, coexistent neck may make airway management more difficult. This may, for example, apply to patients with traumatic brain injury, status epilepticus, or fall from acute hemiplegia of any source. Hyperextension of the neck may potentially worsen or introduce spinal cord lesions. Second, many patients struck with an acute neurologic illness have normal baseline pulmonary function, unlike patients with critical medical illnesses, who often present with an exacerbation of obstructive respiratory disease or become seriously ill from a newly acquired pulmonary disease.1 Gas exchange in acute neurologic catastrophes more often becomes less efficient from impaired mechanisms of breathing involving the respiratory muscles, musculature of the upper airway, and central drive to breathe rather than from impaired pulmonary function. Third, when pulmonary disorders occur, they are most often restricted to aspiration pneumonitis or neurogenic pulmonary edema. Finally, certain modes of mechanical ventilation (particularly hyperventilation) and assessment of respiratory drive (particularly apnea testing) are unique in this category of patients. Our discussion is limited to airway management of respiratory failure, initial modes of the mechanical ventilator, and appropriate care of major pulmonary complications most relevant to patients with an acute neurologic illness. (Detailed accounts in recent textbooks can be consulted to pursue fine points in this matter.2,3) Airway management. Reduced wakefulness decreases the tone of several oropharyngeal muscles, changing the anatomic relationship. The tongue is repositioned to the back wall of …