Which of the following changes in respiratory mechanics occurs ...

[audragclark]

Which of the following changes in respiratory mechanics occurs when a patient switches from positive-pressure breathing to spontaneous ventilation?
 
  A. increased pulmonary compliance
  B. decreased mean pleural pressure
  C. decreased respiratory muscle effort
  D. decreased diaphragmatic involvement

Question 2

Which of the following hemodynamic alterations will occur when a patient transitions from positive-pressure breathing to spontaneous ventilation? I. Venous return increases. II. Left ventricular afterload increases. III. Right ventricular preload decreases. IV. Cardiac output decreases.
 
  A. I, II only
  B. I, II, III only
  C. I, III, IV only
  D. II, III, IV only

[Ahernandez18]

Answer to Question 1

ANS: B
A. Incorrect response: Pulmonary compliance will not be affected by the transition from positive-pressure breathing to spontaneous breathing.
B. Correct response: The mean pleural pressure will decrease when a patient is switched from positive-pressure breathing to spontaneous ventilation.
C. Incorrect response: Respiratory muscle effort increases when a patient assumes a greater work of breathing as occurs when a person changes from positive-pressure breathing to spontaneous breathing.
D. Incorrect response: When a patient assumes an increased work of breathing such as transforming from positive-pressure breathing to spontaneous ventilation, the diaphragm increases contraction to support spontaneous breathing.

Answer to Question 2

ANS: A
A. Correct response: Because a decrease in pleural pressure accompanies the transition from positive-pressure ventilation (PPV) to spontaneous ventilation (SV), and because pleural pressure directly affects the right atrial pressure, venous return increases. The drop in pleural pressure also causes left ventricular afterload to increase.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.

[audragclark]

Excellent

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