Neurological Disorders Q 109

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Which of the following respiratory patterns indicate increasing ICP in the brain stem?

  

     A. Slow, irregular respirations

     B. Rapid, shallow respirations

     C. Asymmetric chest expansion

     D. Nasal flaring

    

    

Correct Answer: A. Slow, irregular respirations

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Neural control of respiration takes place in the brain stem. Deterioration and pressure produce irregular respiratory patterns. Raised intracranial pressure can overcome perfusion pressure causing further anoxia and injury leading to brain death and/or herniation. Although hyperventilation can lower PaCO2, causing vasoconstriction and reduce swelling/ICP, it should be avoided.

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Option B: Central neurogenic hyperventilation is persistent hyperventilation typically caused by head trauma, severe brain hypoxia, or lack of cerebral perfusion. It is usually due to the midbrain and upper pons damage. Breathing patterns associated with brain injury may not be observed due to mechanical ventilation and sedation. There is a complex interplay in cases that result in brainstem injury.

Option C: Central neurogenic hypoventilation occurs when the medullary respiratory centers are not responding to appropriate stimuli. Central neurogenic hypoventilation may occur with head trauma, cerebral hypoxia, and narcotic suppression.

Option D: Rapid, shallow respirations, asymmetric chest movements, and nasal flaring are more characteristic of respiratory distress or hypoxia. The autoregulation of cerebral blood flow is affected by CO2 levels in the blood. As CO2 increases, cerebral vessels will dilate, and as they decrease, the cerebral vessels will constrict. In traumatic brain injury (TBI), the brain swells and cannot expand due to the fixed volume of the intact skull.

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