A patient who just suffered severe closed-head injury and has a ...

[maegan_martin]

A patient who just suffered severe closed-head injury and has a high intracranial pressure (ICP) is about to be placed on ventilatory support. Which of the following strategies could help to lower the ICP?
 
  a. Maintain a PaCO2 from 25 to 30 mm Hg (deliberate hyperventilation).
  b. Allow as much spontaneous breathing as possible (SIMV).
  c. Maintain a high mean pressure using PEEP levels of 10 to 15 cm H2O.
  d. Maintain a PaCO2 of 50 to 60 mm Hg (de-liberate hypoventilation).

Question 2

A patient develops acute hypercapnic respiratory failure due to muscle fatigue. Which of the fol-lowing modes of ventilatory support would you consider for this patient?
 
  1. Assist-control ventilation with adequate backup
  2. Continuous positive airway pressure
  3. Intermittent mandatory ventilation with adequate backup rate
  4. Bilevel pressure support by mask
  a. 2 and 4 only
  b. 3 and 4 only
  c. 1, 2, and 3 only
  d. 1, 3, and 4 only

[guyanai]

Answer to Question 1

ANS: A
Hyperventilation applied acutely and for short periods of time may be used to reduce ICP. The goal is to lower the PaCO2 to between 25 and 30 mm Hg, which causes alkalosis, which in com-bination with hypocapnia helps reduce cerebral blood flow until the ICP can be controlled by other measures.

Answer to Question 2

ANS: D
Noninvasive positive-pressure ventilation can improve hypoxemia and hypercarbia by several mechanisms including but not limited to (1) compensating for the inspiratory threshold load im-posed by intrinsic positive end-expiration pressure, (2) supplementing a reduced tidal volume, (3) partial or complete unloading of the respiratory muscles, (4) reducing venous return and left ven-tricular afterload, and (5) alveolar recruitment.