When watching a routine immunization injection being given to her 2-year-old brother, a teenage girl suddenlycomplains of feeling faint and starts hyperventilating. A nurse has her sit on the floor and gives her a paper bag.What is the rationale for this therapy?A. The higher CO2 content of the bag will correct the patient's compensated respiratory acidosisB. The higher CO2 content of the bag will correct the patient's compensated respiratory alkalosisC. The higher CO2 content of the bag will correct the patient's uncompensated respiratory acidosisD. The higher CO2 content of the bag will correct the patient's uncompensated respiratoryalkalosisE. The paper bag is a placeboExplanation:The correct answer is D. Hyperventilation can be triggered by emotional stress, and the resulting rapidbreathing tends to "blow off" more CO2 from the lung than usual. Since CO2 is carried in the serum principallyas bicarbonate plus hydrogen ion, blowing off CO2 shifts the balance so that less bicarbonate and lesshydrogen ion are present in the blood. Less hydrogen ion translates to higher blood pH, i.e., alkalosis, which inthis case is of respiratory origin. It is an uncompensated respiratory alkalosis, since renal compensation takesseveral days to occur. Re-breathing air, which is easily accomplished by breathing into a paper bag, will slowthe rate of CO2 loss and quickly correct the alkalosis. The manifestations of the type of mild respiratoryalkalosis seen in emotional hyperventilation include light headaches, paresthesias, and sometimes, syncope.Severe respiratory alkalosis (not seen in this setting) can also cause cramps, tetany, seizures, and cardiacarrhythmias.