Why do vasodilators administered via the intravenous route cause ...

[karen]

Why do vasodilators administered via the intravenous route cause an increase in intrapulmonary shunting and a decreased Pao2?
 
  A. because they come in contact with all the vessels of both systemic and pulmonary vasculatures
  B. because they often cause pooling of venous blood in the systemic venous circulation
  C. because they dilate vessels of both ventilated and unventilated alveoli in the pulmonary vasculature
  D. because they cause a decreased cardiac output as an untoward effect

Question 2

The therapist is about to administer a 70-30 heliox mixture to a patient who is to receive NPPV. Which of the following mechanical ventilators should the therapist select for this application?
 
  A. Hamilton Galileo
  B. Aptar
  C. Viasys Avea
  D. No noninvasive positive pressure ventilator can accommodate heliox.

[welcom1000]

Answer to Question 1

ANS: C
A. Incorrect response: See explanation C.
B. Incorrect response: See explanation C.
C. Correct response: In contrast to inhaled NO (iNO), intravenous vasodilators (e.g., sodium nitroprusside and nitroglycerin) are not selective vasodilators. Although intravenous vasodilators lower pulmonary artery pressure, they also lower systemic blood pressure. Moreover, these agents increase blood flow to both ventilated and unventilated alveoli, resulting in increased intrapulmonary shunting and a lower Pao2.
D. Incorrect response: See explanation C.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: The Aptar heliox delivery system is available to deliver heliox with NPPV. It uses a premixed blend of heliox from a source gas cylinder and it delivers to a spontaneously breathing patient through a sealed face mask. The Aptar enables the therapist to adjust the level of pressure support (3 to 20 cm H2O), trigger sensitivity (0.1 to 1.5 cm H2O), rise time, and cycle sensitivity (5 to 75 of peak inspiratory flow). It incorporates a vibrating mesh nebulizer, but does not include an O2 blender or PEEP capabilities.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.

[karen]

Gracias!

[bblaney]

TYSM