Lung volumes and capacities DSA

Question 1

what type of air do you mean when you say “getting wind knocked out of you?”

Answer 1

residual volume (RV)

Question 2

what are the different ways to calculate TLC? what is TLC’s function?

Answer 2

IC+FRC

VC+RV

ERV+RV+IRV+VT

*cannot be measured by spirometry

helps to prevent collapse of lungs, reduces workload, dilutes toxic inhaled gases

and aires the greatest show on TV- My 600 lb life

Question 3

what is the difference between vital capacity (VC) and inspiratory capacity (IC)?

Answer 3

both involve the maximum air inspired

VC- after a maximal expiration

IC- after normal exhale

Question 4

what is normal tidal volume?

Answer 4

500 mL

Question 5

what are some influences on lung volumes?

Answer 5

• age- FVC, FRC, RV all increase with age
• posture- reduced FRC when laying down (RV does not change)
• sex
• ethnicity
• obesity- decreases all types of volume except tidal volume
• pulmonary disease

Question 6

what 3 ways do we measure RV?

Answer 6

1. helium dilution- inhale it and then measure the concentration exhaled
2. body plethysmograophy- put a person in a box then measure the box pressure changes (opposite to that of person)… uses Boyle’s Law (P1V1=P2V2)
3. nitrogen-washout: determines FRC by having person breath out until all N2 is gone then calculation is done