Ventilation

Question 1

static volumes are measured with a

Answer 1

spirometer

Question 2

tidal volume

Answer 2

volume of air entering or leaving the lungs during a single breath

• includes volume that fills alveoli and volume that fills the airways

Question 3

inspiratory reserve volume

Answer 3

additional volume inspired above tidal volume

• used in exercise

Question 4

expiratory reserve volume

Answer 4

additional volume expired below tidal volume

Question 5

residual volume

Answer 5

volume of gas left in lungs after maximal forced expiration

Question 6

inspiratory capacity

Answer 6

tidal volume + inspiratory reserve volume

Question 7

functional residual capacity

Answer 7

• volume of air in the lungs at the end of a normal passive expiration (or normal tidal volume)
• Expiratory reserve volume + residual volume
• **resting volume of lungs

Question 8

vital capacity

Answer 8

• volume expired after maximal inspiration
• VC= inspiratory capacity + expiratory resperve volume
• VC= tidal volume + inspiratory reserve volume + expiratory resperve volume

Question 9

vital capacity increases with? decreased with?

Answer 9

• increases
  
  • sex (M>F)
  • body size
  • physical conditioning
• decreases
  
  • age

Question 10

total lung capacity

Answer 10

• maximal volume of air that the lungs can hold
• TLC= vital capacity + residual volume

Question 11

functional residual capacity (FRC)

Answer 11

volume remaining in the lungs after a normal expiration

• resting volume of lungs
• can not be measured by spirometery

Question 12

normal residual volume/total lung capacity

Answer 12

less than or equal to 0.25

*volume of air trapped in the lungs in 25% of the total lung volume

Question 13

obstructive lung disease (emphysema) has what affect on RV/TLC ratio

Answer 13

• RV increases therefore RV/TLC ratio increases
• **see barrel shaped chest

Question 14

restrictive lung disease (fibrosis) has what affect on RV/TLC ratio

Answer 14

• TLC decreases thus RV/TLC ratio increases

Question 15

dead space. Comprised of what two parts?

Answer 15

• volume of airways and lungs not involved in gas exchange
• comprised of
  
  • anatomic dead space
    
    • conducting zone (nose, trachea, bronchi, bronchioles)
  • physiologic dead space

Question 16

physiologic dead space. Name normal equation and abnormal equation

Answer 16

total volume of lungs not participating in gas exchange

• abnormal
  
  • physiologic dead space = anatomic dead space + functional dead space in alveoli
  • V/Q mismatch
• normal
  
  • physiologic dead space = anatomic dead space
  • V/Q matched

Question 17

volume of physiologic dead space is calculated based on the pp of CO2 in expired air and what 3 assumptions

Answer 17

1. all CO2 in expired air comes from alveolar exchange
2. no CO2 in inspired air
3. physiologic dead space does not exchange nor contributes to CO2

Question 18

physiologic dead space is calculated using the following equation

Answer 18

V_D=V_T x (Pa_CO2-PE_CO2) / Pa_CO2

• Pa_CO2 = P_CO2 of arterial blood
• PE_CO2 = P_CO2 of expired air
• VT= tital volume
• Vd= physiologic dead space

Question 19

alveolar air equilibriates with arterial blood. what does this mean for pressures

Answer 19

Pa_CO2 = PA_CO2

• PA_CO2= alveolar
• Pa_CO2 = arterial

Question 20

minute ventilation equation

Answer 20

• total rate of air movement into/out of lungs
• minute ventilation = tidal volume x breaths/min

Question 21

alveolar ventilation equation that corrects for physiologic dead space

Answer 21

• alveolar ventilation = (V_T-V_D) x breaths/min

Question 22

alveolar ventilation equation that relates alveolar ventilation and alveolar P_CO2

Answer 22

alveolar ventilation = (V_CO2 x K) / PA_CO2

• V_CO2 = rate of CO2 production
• k = constant
• **thus if CO2 production is constant, PA_CO2 is determined by alveolar ventilation (hyperbolic relationship)

Question 23

if CO2 production is constant, PACO2​ is determined by alveolar ventilation (hyperbolic relationship). What happens if CO2 production doubles from strenuous exercise?

Answer 23

• alveolar ventilation must also double to maintain PA_CO2 and Pa_CO2
• curve shifts to the right

Question 24

Forced expiratory volume in one second (FEV1)

Answer 24

volume of air that can be forcible expired in the 1st second

Question 25

Normal FEV1/FVC ratio

Answer 25

0. 8
   * 80% of the vital capacity can be forcibly expired in the 1st second

Question 26

FEV1/FVC ratio in airway restrictive disease (e.g. fibrosis)

Answer 26

• Both FEV1 and FVC are decreased
  
  • BUT FVC decreases more than FEV1
  • therefore FEV1>FVC
• FEV1/FVC increases

Question 27

FEV1/FVC ratio in airway obstructive disease (e.g. asthma)

Answer 27

• Both FEV₁ and FVC decrease
  
  • BUT FEV₁ decreases more than FVC
  • therefore FVC>FEV₁
• FEV₁/FVC decreases