SM_174a-175a: Pulmonary Function Flashcards
Obstructive lung diseases include _____, _____, and _____
Obstructive lung diseases include emphysema, chronic bronchtis, and asthma
In obstructive lung diseases, the lungs are _____ and may _____ gas
In obstructive lung diseases, the lungs are hyperinflated and may trap gas
In emphysema, _____ elastic recoil pressure _____ resting lung volume, and _____ elastic recoil pressure and tendency of airways to collapse _____ exhalation
In emphsema, decreased elastic recoil pressure elevates resting lung volume, and decreased elastic recoil pressure along with the tendency of airways to collapse limits exhalation
In chronic bronchitis and asthma, airflow obstruction occurs because of _____
In chronic bronchitis and asthma, airflow obstruction occurs because of increased airway resistance
(due to some combo of intraluminal mucus, airway wall edema, bronchospasm, and airway wall remodeling)
An example of a restrictive lung disease is ____
An example of a restrictive lung disease is IPF
Restrictive lung diseases are characterized by ______
Restrictive lung diseases are characterized by low lung volumes
In pulmonary fibrosis, lung volume is decreased because of ______
In pulmonary fibrosis, lung volume is decreased because of increased elastic recoil pressure (decreased lung compliance)
Spirometry measures _____
Spirometry measures expiratory flow rates
FVC = _____ - _____
FVC = TLC - RV
FEV1 is defined as the ____
FEV1 is defined as the forced expiratory volume in the first second of trying
Normal FEV1 / FVC = _____
Normal FEV1 / FVC = 75%
(drops with age)
In obstructive lung disease, FEV1 _____, FVC _____, and FEV1 / FVC _____
In obstructive lung disease, FEV1 decreases, FVC decreases or stays constant, and FEV1 / FVC decreases
( FEV1 / FVC < 0.7 indicates obstructive lung disease)
Why does FEV1 / FVC decrease in obstructive lung disease?
FEV1 / FVC decreases in obstructive lung disease
- FEV1 decreases because of decreased lung elastic recoil pressure or increased airway resistance
- FVC may not fall as much because motivated patients may exhale over a longer period
- This time compensation results in less of a decrease in FVC relative to FEV1, which decreases FEV1 / FVC
In restrictive lung disease, FEV1 ______, FVC ______, and FEV1 / FVC ______
In restrictive lung disease, FEV1 decreases, FVC decreases, and FEV1 / FVC increases
Why does FEV1 / FVC increase in restrictive lung disease?
FEV1 / FVC increases in restrictive lung disease
- Airflow flow rates plotted at isovolume flow (absolute lung volume) may be higher than normal because elastic recoil pressure is higher and airway resistance is lower than normal
- Exhalation time may be shorter than normal
Normalization of FEV1 and FVC following albuterol suggests the patient has _____
Normalization of FEV1 and FVC following albuterol suggests the patient has asthma
(asthma patients can have normal pulmonary function when asymptomatic)
In asthma patients, methacholine causes _____ in spirometric measures that _____ with rescue albuterol
In asthma patients, methacholine causes a drop in spirometric measures that improves with rescue albuterol
Diffusing capacity for carbon monoxide (DLCO) measures the ______
Diffusing capacity for carbon monoxide (DLCO) measures the uptake of inhaled carbon monoxide by hemoglobin
DLCO is increased when _____
DLCO is increased when there is increased hemoglobin in areas of intact ventilation (alveolar hemorrhage, polycythemia)
(breathe in CO but exhale less CO than expected so CO was taken up)
DLCO is decreased when _____
DLCO is decreased when ventilation does not match perfusion (low V/Q) or when there is loss of blood (anemia, R->L shunt) or loss of functional blood vessels (pulmonary embolism, emphysema, interstitial lung disease)
(breathe in CO but exhale more CO so CO was not taken up)
Describe the lung volumes and capacities
- FRC: resting lung volume (volume of lung at end of a quiet tidal breath), which is determined by inward elastic recoil of lung and outward elastic recoil of the chest wall
- IC = TLC - FRC
- TLC: amount of air present within lungs when they are maximally inflated
- RV: amount of air present within lungs when they are maximally deflated
- ERV = FRC - RV
- IRV = IC - TV
- TV: amount of air inspired during quiet breath
The width of the flow volume loop is ____
The width of the flow volume loop is FVC
Draw the flow-volume loop for an obstructive lung disease and for a restrictive lung disease
- Obstructive lung disease: scooped / concave up
- Restrictive lung disease: narrow
(note that curves may face right or left depending on software used)
The normal inspiratory loop on a flow-volume curve is _____
The normal inspiratory loop on a flow-volume curve is symmetric and U-shaped
Flattening of the inspiratory loop on the flow-volume curve suggests _____ or _____
Flattening of the inspiratory loop on the flow-volume curve suggests inadequate strength/effort/technique during the forced inhalation maneuver or upper airway obstruction (vocal cord dysfunction, epiglottitis, laryngeal edema, or laryngeal malignancy)
The normal expiratory loop on a flow-volume curve is ______ because _______
The normal expiratory loop on a flow-volume curve is asymmetric because higher expiratory flows are generated at larger lung volumes
(this is because elastic recoil pressure is greater and airway resistance is lower via tethering effects of alveoli at higher lung volumes)
Normal expiratory loop on a flow-volume curve is asymmetric because higher expiratory flows are generated at larger lung volumes due to _____ and _____
Normal expiratory loop on a flow-volume curve is asymmetric because higher expiratory flows are generated at larger lung volumes due to:
- greater elastic recoil pressure
- lower airway resistance resulting from the inflated lung pulling the airways open via the tethering effects of alveoli
V·max = _____ / _____
V·max = Pel / Rairway
(maximal expiratory airflow = elastic recoil pressure / resistance upstream to the equal pressure point)
Palv is alveolar pressure, Ppl is pleural pressure
Once a certain threshold expiratory effort is generated, greater efforts _____ expiratory flow rates
Once a certain threshold expiratory effort is generated, greater efforts do not increase expiratory flow rates
(this is called effort independence)
(greater efforts countered by more airway compression)
Expiratory flow rates are greater at _____ lung volume, which is where Pel is _____ and Rairway is _____
Expiratory flow rates are greater at larger lung volume, which is where Pel is high and Rairway is low
Describe the volume-time curve for obstructive lung disease and restrictive lung disease
Volume-time curve
- Obstructive lung disease: expire less air in first second, can reach same expired volume after much longer time
- Restrictive lung disease: limit to the amount of air that can be expired
Expiratory airflow is decreased most by ____ and _____
Expiratory airflow is decreased most by low Pel and high Rairway
Emphysema is best characterized by ______
Emphysema is best characterized by hyperinflation with low DLCO
Isovolume airflow is high in ______
Isovolume airflow is high in pulmonary fibrosis
(restrictive lung disease)
Which test result regarding FEV1 / FVC suggests asthma?
Low FEV1 / FVC that normalizes after albuterol
Flattening of the inspiratory loop can be caused by _______ obstruction
Flattening of the inspiratory loop can be caused by variable extra-thoracic (upper) airway obstruction
(also by inadequate strength, effort, or technique during forced inhalation maneuver)
V·max = ____ / _____
V·max = Pel / R where Pel is elastic recoil pressure of lung and R is resistance of airway
- Tethering of alveoli keeps airway open
- Higher lung volumes increase Pel
- At TLC, Pel is high and R is low, which helps generate high flow
In obstructive lung disease, lung volumes are _____
In obstructive lung disease, lung volumes are normal or increased
In restrictive lung disease, lung volumes are _____
In restrictive lung disease, lung volumes are decreased
In emphysema, the expiratory part of the flow-volume curve is _____
In emphysema, the expiratory part of the flow-volume curve is scooped out / concave (obstructive lung disease)
- Damage to alveoli causes loss of elastic recoil
- Pel decreases so peak flow decreases and flows are decreased at any given volume
- Airways collapse due to loss of tethering of elastic structure
In chronic bronchitis, the expiratory part of the flow-volume curve is _____
In chronic bronchitis, the expiratory part of the flow-volume curve is scooped out / concave (obstructive lung disease)
- Larger airways are narrowed so R increases
In asthma, the expiratory part of the flow-volume curve is ______
In asthma, the expiratory part of the flow-volume curve is scooped out / concave
- Airways narrowed so R increases so V·max decreases (flow decreases)
In obstructive lung disease, FEV1 / FVC ______
In obstructive lung disease, FEV1 / FVC decreases
(FEV1 and FVC decrease but the ratio decreases due to time compensation)
(< 0.7 is obstructive lung disease)
In restrictive lung disease, FEV1 / FVC ______
In restrictive lung disease, FEV1 / FVC increases
- Isovolume flow higher than health
- Width on flow-volume curve is narrower: FVC decreases
