ventilation perfusion relationship

Question 1

partial pressure

Answer 1

exerted by a single gas within a mixture of gases

Question 2

daltons law of partial pressure

Answer 2

Total pressure equals the sum of the partial pressures of the individual gases in a mixture of gases.

Question 3

atmospheric pressure

Answer 3

Pressure exerted by the weight of air molecules above a given subject

Question 4

components of air

Answer 4

N2, O2, CO2, Ar

Question 5

partial pressure and percentage of atmospheric O2 at sea level

Answer 5

159 mmHg
20.84%

Question 6

what is the gas composition of O2 of humidified air at sea level

Answer 6

149.3 mmHg
19.67 %

Question 7

factors that play a role in partial pressure of alveolar gas?

Answer 7

Fraction of inspired O2 (FiO2)
Barometric pressure (PB)
Vapor pressure of H2O (PH2O)
Partial pressure of expired CO2 (PaCO2)
Respiratory quotient

Question 8

what is the respiratory quotient

Answer 8

The ratio between carbon dioxide production and oxygen consumption.

Question 9

gas composition of alveolar air at sea level

Answer 9

100

Question 10

gas exchange in lungs is determined by

Answer 10

Ventilation/perfusion (V/Q) ratio of a lung unit
Absolute amounts of V/Q ratios of multiple lung units

Question 11

Ventilation/perfusion = What determines the concentration of O2 in the alveolar compartment and, therefore, in the effluent blood?

Answer 11

-Rate at which O2 is added (ventilation)
-Rate at which blood (with O2) is pumped (blood flow–perfusion)
-Concentration of O2 is determined by the ratio of these rates

Question 12

areas of lungs that are well ventilated will have

Answer 12

poor perfusion

Question 13

areas of lungs that are well perfused will have

Answer 13

poor ventilation

Question 14

t/f ventilation and perfusion vary from top to bottom in the lungs

Answer 14

true

Question 15

at the base of the lung there is

Answer 15

higher perfusion than ventilation

Question 16

effect of V/Q inequality on overall gas exchange

Answer 16

is not able to adequately transfer O2 and CO2
hypoxemia = lower than normal PaO2
Hypercapnia (higher than normal PaCO2)

Question 17

When V/Q is lower than normal

Answer 17

“physiologic (intrapulmonary) shunt”

Question 18

When V/Q is greater than normal

Answer 18

“physiologic dead space”

Question 19

The greater the physiologic shunt

Answer 19

the greater the amount of blood that fails to be oxygenated as it passes through the lungs

Question 20

t/f there is a higher partial pressure of O2 in the alveolus than in arterial blood

Answer 20

true

Question 21

why is there a difference in partial pressure In alveolus and arterial blood?

Answer 21

Diffusion can occur due to pressure gradient

Question 22

causes of hypoxemia

Answer 22

Hypoventilation
Diffusion limitation
Ventilation-perfusion mismatch
Right-to-left anatomical shunts

Question 23

define hypoxemia

Answer 23

partial pressure of O2 lower than normal in arterial blood

Question 24

hypoventilation is determined by the alveolus, 2 factors affected It

Answer 24

Rate of removal of O2 by blood
Rate of replenishment of O2 by alveolar ventilation

Question 25

with hypoventilation there will be an increase of

Answer 25

CO2 in alveolus and arterial blood

Question 26

causes of hypoventilation

Answer 26

Drugs Opioids, sedatives, barbiturates and other anesthetics Paralysis of respiratory muscles and nerves Trauma to the chest wall Tracheal and airway obstruction

Question 27

treatment for hypoventilation

Answer 27

O2 saturation increase ventilationn

Question 28

what causes diffusion limitation

Answer 28

Decreased capillary transit time of red blood cells= Strenuous exercise at high altitude Thickening of the blood-gas barrier = Rate of rise of PO2 in the red cells is slow, so the PO2 may not reach that of the alveolar gas before red cell leaves the pulmonary capillary

Question 29

shunt perfusion are usually caused by

Answer 29

atelectasis obstructive Mucus plugs Upper airway foreign bodies Tumors non obstructive Pneumothorax Diaphragmatic hernia Increased intraabdominal pressure (e.g., laparoscopy, gastrointestinal distention) Recumbency under general anesthesia

Question 30

dead space ventilation is usually caused by

Answer 30

pulmonary embolism cardiogenic shock

Question 31

what causes increased physiological dead space

Answer 31

Anything that decreases pulmonary blood flow Hypotension Hypovolemia Decreased cardiac output Shock Pulmonary thromboembolism

Question 32

causes of right to left anatomical shunt

Answer 32

Reverse patent ductus arteriosus (PDA) Tetralogy of Fallot

Question 33

how do you fix a right to left anatomical shunt?

Answer 33

correct the anatomical defects