Lec37_Physiology Testing in Respiratory Disease Flashcards
What is FVC [forced vital capacity]?
volume of air a subject can exhale after maximal inspiration to total lung capacity
What is FEV1 [forced expiratory vol in 1 sec]?
volume of air exhaled in first second of expiration
What is TV? What is normal value?
volume of air inhaled and exhaled during quiet breathing [500 mL]
What is IRV? What is normal value?
additional volume that can be inspired above TV [3000 mL]
What is ERV? What is normal value?
additional volume that can be expired below TV [1200 mL]
What is RV?
residual volume
vol of gas in lungs after a maximal forced expiration [1200 mL]
What is IC?
IC = TV + IRV
inspiratory capacity?
What is FRC?
FRC = ERV + RV
- equilibrium vol of lungs
What is VC?
VC = IC + ERV
- vol expired after maximal inspiration
What is TLC?
TLC = VC+RV
- total vol of air in lungs after max inspiration
What is average Pe max?
170 cm H2O
what is average Pi max?
-100 cm H2O
What is diffusing capacity? What is molecule used to assess? What is the limiting factor of its diffusion?
- assess gas exchange ability of lungs
- CO chosen because it binds hemoglobin with highest affinity
- limiting factor is the status of alveolocapillary membrane
What is equation for diffusing capacity? maybe more than we need to know
DLco = V.CO / PACO - Pc-Co] DLco = diffusing capacity V.CO = rate CO taken up by lung PACO = partial pressure CO in alveoli Pc-CO = capillary/venous pressure
What happens to FEV1 and FVC in obstructive lung disease like asthma? what about FEV1/FVC ratio?
air doesn’t come out fast, needs longer to plateau
much lower FEV1, slightly lower FVC
very reduced FEV1/FVC ratio
“scooping out” in flow vs volume graph
What happens to FEV1 and FVC in restriction? what about FEV1/FVC ratio?
decreased FEV1 and decreased FVC
normal FEV1/FVC ratio
What does the width of the triangle curve in flow vs volume curve signify?
FVC
What happens to obstruction in flow vs volume graph?
relative total lung capacity increased after full breath but can’t get all the air out
- hyperinflation = increased TLC
- difficulty expiring = increased RV
In restriction what happens to FEV1, FVC, FEV1/FVC, RV, and TLC in restriction?
FEV1: very decreased FVC: very decreased FEV1/FVC: no change or slightly increased RV: decreased TLC: decreased
In restriction what happens to FEV1, FVC, FEV1/FVC, RV, and TLC in obstruction?
FEV1: very decreased FVC: slightly decreased FEV1/FVC: decreased RV: increased TLC: increased
What are 3 examples of obstructive lung disease?
- asthma
- ephysema
- chronic bronchitis
what are 3 examples of restrictive lung disease?
- interstitial lung disease [pulm fibrosis]
- neuromuscular disease [weakness, myasthenia gravis]
- obesity [because there push up on diaphragm making smaller lung vol]
what 2 things can increase diffusing capacity?
- more Hgb binding sites
- more blood flow to chest
How does number of Hgb binding sites affect diffusing capacity?
more binding sites = high diffusing capacity
