In patients with closed-head injuries, what may happen in the ...

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In patients with closed-head injuries, what may happen in the presence of hypercapnia?
 
  a. High CO2 increases the risk of psychotic events.
  b. High CO2 levels cause cerebral vasodila-tion and improved oxygenation.
  c. Severe cerebral vasoconstriction results in anoxia and stroke.
  d. Vasodilation causes increased intracranial pressure and possibly stops blood flow.

Question 2

You observe a patient's breathing pattern as very irregular, with periods of breathing interspersed with long periods of apnea. Which of the following terms would you use in charting this obser-vation?
 
  a. Apneustic breathing
  b. Biot's respiration
  c. Cheyne-Stokes breathing
  d. Kussmaul's breathing

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Answer to Question 1

ANS: D
Increased PCO2 dilates cerebral vessels, raising cerebral blood flow, whereas decreased PCO2 constricts cerebral vessels and reduces cerebral blood flow. In patients with traumatic brain inju-ry, the brain swells acutely; this raises the intracranial pressure in the rigid skull to such high lev-els that blood supply to the brain might be cutoff, causing cerebral hypoxia (ischemia). That is, high intracranial pressure may exceed cerebral arterial pressure and stop blood flow.

Answer to Question 2

ANS: B
Biot's respiration is similar to Cheyne-Stokes respiration, except that tidal volumes are of identi-cal depth.

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