q2 - 2confused2bdoctor

[ArchivalUser]

healthy 42 yr. old woman with a history of anxiety attacks sits in the hospital waiting room as her 3-
year-old daughter undergoes open heart surgery for a septal malformation. The woman experiences a
feeling of suffocation and is obviously hyperventilating. She informs her husband that she feels faint and
has blurred vision. Which of the following is most likely to relieve the symptoms caused by
hyperventilation?
A. Breathing a 10% oxygen/90% nitrogen mixture
B. Breathing 100% nitrogen
C. Breathing in and out of a plastic bag
D. Intravenous administration of bicarbonate
E. Lying down

[ArchivalUser]

ccc

[ArchivalUser]

CCCCCCCC

[ArchivalUser]

c...prevents co2 wash out i think..jus logic

[ArchivalUser]

cc

[ArchivalUser]

rebreath co2

cc

[ArchivalUser]

The correct answer is C. Hyperventilation associated with states of anxiety can lead to
feelings of faintness, suffocation, tightness in the chest, and blurred vision. Individuals
undergoing such an attack may not be aware of overbreathing. The anxious,
hyperventilating woman is "blowing off" carbon dioxide, which lowers her arterial PCO2.
Many of the symptoms associated with anxiety attacks are probably caused by a
decrease in cerebral blood flow secondary to low arterial PCO2. Recall that carbon
dioxide is a major regulator of cerebral blood flow, i.e., carbon dioxide dilates the brain
vasculature, and conversely, the vasculature constricts when carbon dioxide levels are
low. The decrease in cerebral blood flow leads to cerebral hypoxia, which is probably
responsible for the fainting and blurred vision. An attack may be terminated by breathing in
and out of a plastic bag because this can increase carbon dioxide levels in the blood.
Inhaling a 5% carbon dioxide mixture would also be effective