3 lung volumes/airway function

Question 1

ventilation? oxygenation?

Answer 1

V = exchange of gas b/w lung and environment. O = addition of oxygen to blood.

Question 2

airway obstruction is defined by?

Answer 2

decrease in ration of FEV1/FVC < 88% predicted = < 0.75 if young, or < 0.70 if old

Question 3

obstruction can be ___, ____ or ______. examples of obstruction?

Answer 3

fixed, reversible, partially reversible. COPD (emphysema, chronic bronchitis), sarcoidosis, long standing asthma, cystic fibrosis

Question 4

restriction definition

Answer 4

decreased total lung capacity (lung volume at max. volume)

Question 5

restrictive defects are caused by? (3 categories)

Answer 5

stiff lungs that are difficult to inflate (pulm. fibrosis, thickening of visceral pleura, pulm. edema, etc.) chest wall disease (obesity, structural changes, resp muscle weakness), pleural space disease (pneumothorax, pleural effusion)

Question 6

obstruction vs. restriction: lung volumes?

Answer 6

obstruction = higher volumes. restriction = lower.

Question 7

FRC stands for? determined by balance of? def?

Answer 7

functional residual capacity: balance of lung elastic recoil (wants to collapse) and chest wall recoil (wants to spring out). = vol of gas in lungs when no work being done by muscles

Question 8

size of airways at TLC vs. FRC

Answer 8

airways bigger at TLC (so enlarge during inspiration). smaller at FRC, they get smaller when you breathe out.

Question 9

definitions of FRC? TLC? RV? VC?

Answer 9

FRC: vol of lungs at start of a normal tidal volume inspiration. TLC= max lung volume, RV= min. VC = max volume of air that can be exhaled after a full inspiration to TLC.

Question 10

how does obstruction lead to hyperinflation

Answer 10

narrow and high resistance airways close during exhalation = can’t empty the lungs –> VC decreased, but FRC increased

Question 11

Palv (alveolar pressure) = ?

Answer 11

sum of Pst aka natural recoil of lungs and Ppl aka pressure outside lungs in pleural space

Question 12

what happens to FRC in obesity

Answer 12

decreased –> so decreases diameter of airways; then mistakenly thought to have airway disease

Question 13

flow equation

Answer 13

flow = pressure difference / resistance aka difference between alveolar and atm. pressure divided by total airway resistance

Question 14

flow equation: pleural pressure depends on?

Answer 14

effort

Question 15

FEV1 is what? depends on what?

Answer 15

volume exhaled forcibly in 1 second: affected by resistance in larger airways, and is effort dependent