Vent/Perfusion

Question 0

What is the equation for minute alveolar ventilation?

Answer 0

VA= (Vt-VD) x f

Question 1

What is the equation for Total Lung Ventilation?

Answer 1

Vt= VA+VD

Question 2

The cause of elevated PaCO2

Answer 2

Alveolar Hypoventilation “retaining CO2”

Question 3

Causes a decreased PaCO2

Answer 3

alveolar hyperventilation “blowing off CO2”

Question 4

What is Deadspace Volume (VD)?

Answer 4

Volume of inspired air that does not participate in gas exchange

Question 5

Volume of air in the conducting airways is…

Answer 5

Anatomic deadspace

Question 6

In normal adults the deadspace is ______ /______ of the predicted body weight.

Answer 6

1ml/1lb

Question 7

Formula for predicted body weight.

Male and Female

Answer 7

106+6(height-60) (Male)

105+5(height-60) (female)

Question 8

Volume of gas that does not participate in gas exchange is

Answer 8

Alveolar deadspace

Question 9

List 4 causes of alveolar deadspace.

Answer 9

No blood flow to alveoli (pulmonary embolism)

Decrease in cardiac output

Low blood flow to certain area (plaque)

Over inflated alveoli

Question 10

What is the sum of alveolar deadspace and Anatomic deadspace called…

Answer 10

Physiologic deadspace

Question 11

Mechanical deadspace is …

Answer 11

The volume of rebreathed gas added by equipment.

Question 12

Deadspace to Tidal Volume Ratio (VD/VT)

Answer 12

Representative of effective ventilation.

VD/VT= (PaCO2-PECO2) / (PaCO2)

“PACO-PECO-PACO”

Question 13

What is the normal range for VD/VT?

Answer 13

.20 -.40

Question 14

Zone with no blood flow (non-dependent)

Answer 14

Zone I

Question 15

Zone where blood flow is pulsatile.

Answer 15

Zone II

Question 16

Zone where blood flow is continuous

Answer 16

Zone III

Question 17

The portion of the cardiac output (C.O.) that enters the left heart without exchanging gases at the alveoli (wasted perfusion, perfusion w/o ventilation)

Answer 17

Shunt

Question 18

(2-5% of C.O.) some bronchial, pleural, and thebesian veins empty into pulmonary vein or left heart. ( Venous admixture ) incr. CO2 decr. O2

Answer 18

Normal anatomical shunt

Question 19

Due to septal defects, defects in the pulmonary circulation (right and left shunt). Atrium septum defects, ventricular septum defects. Incr. PCO2. Decr. O2

Answer 19

Pathologic Anatomic shunt

Question 20

Results from pulmonary capillary blood in contact with unventilated alveoli.

Answer 20

Absolute (true) shunt

Question 21

Perfusion in excess of ventilation

Answer 21

Relative shunt (shunt effect). O2 therapy will work.

Question 22

Equation for estimating shunt …

Answer 22

Alveolar to arterial PO2 gradient.

A-aDO2
PAO2-PaO2

Question 23

Normal range for alveolar to arterial PO2 gradient with PT on 21% O2

Answer 23

<5 to 25 mmHG

Question 24

Equation for percent shunt

Answer 24

Qs/QT

Question 25

____ % shunt is normal

Answer 25

<10%

Question 26

_____% shunt is some abnormality

Answer 26

10-20%

Question 27

_____% shunt is significant disease.

Answer 27

20-30%

Question 28

_____% shunt is life threatening.

Answer 28

> 30%

Question 29

The greater the _____ the more the shunt.

Answer 29

Gradient

Question 30

What is the normal range for the ventilation/perfusion ratio (V/Q)

Answer 30

0.8

V=4 L/min
Q= 5 L/min

Question 31

What is the normal range for the ventilation/perfusion ratio (V/Q)
* Apices*

Answer 31

Lung Apices >.8. (Non dependent)

Question 32

What is the normal range for the ventilation/perfusion ratio (V/Q)
lung bases

Answer 32

Lung bases <.8 (dependent, more perfusion and less vent)

Question 33

An increase in (V/Q) indicates ….

Answer 33

Increased deadspace

Question 34

A decrease in (V/Q) indicates….

Answer 34

Increased shunt

Question 35

The ratio of Co2 produced to the O2 consumed is called..

• equation
• normal values

Answer 35

Respiratory Quotient (RQ)

VCO2/VO2.

200 mL/min
____________
250 mL/min