Author Question: With which of the following pressures does the therapist need to be most concerned regarding the ... (Read 229 times)

jilianpiloj · **on:** Jul 16, 2018

With which of the following pressures does the therapist need to be most concerned regarding the effects of positive-pressure breathing on the cardiovascular system during mechanical ventilation?

A. alveolar pressure
B. airway pressure
C. pleural pressure
D. transairway pressure

Question 2

Which of the following statements accurately describe pulmonary vascular capacitance? I. During lung inflation, vascular capacitance increases within the alveolar vessels. II. During hypervolemic states, lung inflation causes a discharge of alveolar blood volume into the left atrium. III. During dehydration, lung inflation will cause a transient decrease in the pulmonary venous overflow as blood pools in the extra-alveolar vessels. IV. Vascular capacitance decreases in the extra-alveolar vessels during lung inflation.

A. III only
B. I, II, IV only
C. I, III, IV only
D. II, III, IV only

janeli · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
A. Incorrect response: Alveolar pressure is often represented by the plateau, or static, pressure. It is also called the alveolar distending pressure and is used in the calculation of static compliance.
B. Incorrect response: The airway pressure is usually measured in the ventilator breathing circuit.
C. Correct response: Pleural pressure, estimated by esophageal pressure, is the pressure in the pleural space. During spontaneous breathing, pleural pressure is always subatmospheric. However, during positive-pressure mechanical ventilation, pleural pressure becomes supra-atmospheric. Because of its proximity to the major cardiovascular structures (heart, pulmonary circulation vena cava, and aorta), pleural pressure closely reflects the impact imposed by positive-pressure breathing on blood flow.
D. Incorrect response: Transairway pressure is the pressure gradient responsible for the flow of air into and out of the lungs.

Answer to Question 2

ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: As the lungs inflate, alveolar vessels are compressed and they
experience a decrease vascular capacitance. At the same time, the extra-alveolar vessels experience an increased pulmonary capacitance. If alveolar capillaries are engorged with blood as during a hypervolemic state, inspiration causes a discharge of alveolar-capillary blood volume into the left atrium. However, if alveolar capillaries are less full, as in the case of hydration lung, inflation will result in a transient decrease in pulmonary vessel outflow as blood pools in the enlarged extra-alveolar vessels.