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Board Review CRNA (Memory Master) > Ventilation:Perfusion > Flashcards

Flashcards in Ventilation:Perfusion Deck (16)
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1

Compared with the apex of the lung, the base of the lung exhibits (when the individual is awake and upright) greater or lesser perfusion?

Greater. Perfusion (blood flow) is best in dependent lung. The base of the lung is dependent in the upright (sitting or standing) individual.

2

What is the principle reason blood flow to dependent lung is greater than blood flow to non-dependent lung?

Gravity.

3

Compared with the apex of the lung, the base of the lung exhibits (when the individual is awake and upright) greater or lesser ventilation?

Greater. Total ventilation is best in dependent lung.

4

In the awake spontaneously breathing patient in the lateral decubitus position, where is ventilation best (dependent or nondependent lung), and where is perfusion best (dependent or nondependent lung)?

In the awake spontaneously breathing patient in the lateral decubitus position, ventilation is best in dependent (lower) lung and perfusion is best in dependent (lower) lung.

5

In the anesthetized and paralyzed patient in the lateral decubitus position, where is ventilation best (dependent or nondependent lung), and where is perfusion best (dependent or nondependent lung)?

When the patient in the lateral decubitus position is anesthetized and paralyzed, perfusion is best in the dependent (lower) lung, but ventilation is best in the nondependent upper lung.

6

The healthy adult lung receives each minute an alveolar ventilation of about how many liters and a pulmonary blood flow of how many liters? What is the average resting ventilation:perfusion (V/Q) ratio?

4 l/min is the alveolar ventilation rate (V). 5 l/min is the pulmonary blood flow (Q). Normally, V/Q = 0.8 [(4L/min)/(5 L/min) = V/Q = 0.8].

7

What is the importance of maintaining a normal ventilation-to-perfusion relationship?

A normal ventilation-to-perfusion relationship is required to keep PaCO2 and Pa02 in the normal range.

8

In a lung unit that exhibits absolute shunt, what is the V/Q ratio, the amount of ventilation, and the amount of perfusion?

In a lung unit that exhibits absolute shunt, V/Q = 0 because V = 0; perfusion (Q) may be decreased somewhat because of hypoxic pulmonary vasoconstriction.

9

A V/Q ratio between zero and unity (0 < V/Q < 1) indicates what?

A V/Q ratio between zero and unity (0 < V/Q < 1) indicates a relative shunt.

10

What is indicated by a V/Q ratio that is greater than one (V/Q > 1)?

A V/Q > 1 indicates deadspacing.

11

What is the V/Q ratio in a lung that is ventilated but completely unperfused (eg pulmonary emboli)?

V/Q = infinity if the lung unit is ventilated and completely unperfused, because Q = 0.

12

State the numeric values for absolute deadspace and absolute shunt.

With absolute deadspace, V/Q = infinity (V/0) and with absolute shunt, V/Q = 0 (0/Q).

13

Describe how gravity affects the size of alveoli.

At end-expiration, dependent alveoli are smaller than nondependent alveoli.

14

Compared with the apex of the lung, the base of the lung exhibits (when the individual is awake and upright) higher or lower V/Q ratio?

Lower. The V/Q ratio is high in nondependent lung and low in dependent lung.

15

What are the consequences of clipping a bronchus but
leaving the vasculature intact during left pneumonectomy?

An intrapulmonary shunt develops if a bronchus is clipped and the vasculature is left intact. When a shunt develops, Pa02 decreases.

16

Why does a patient who has two lungs, but only one
functioning properly, present a problem, whereas a patient with one lung lives a fairly normal life?

There is a large shunt when one lung is nonfunctional. Pa02 decreases possibly/probably resulting in arterial hypoxemia. If the lung is removed, there is no shunt and hence there is no arterial hypoxemia.