PFTs Flashcards
PFTs
Spirometry
Spirometry before and after a bronchodilator
Flow-volume loops
Lung volumes
Quantitation of diffusing capacity for carbon monoxide
Additional PFTs: measurement of maximal respiratory pressures, submaximal exercise testing, pulse oxygen saturation, arterial blood gases
Forced vital capacity (FVC)
maximal volume of air exhaled with a maximally forced effort from a position of full inspiration
FEV1
The forced expiratory volume in one second- maximal volume of air exhaled in the first second of a forced exhalation that follows a full inspiration
The slow vital capacity (SVC)
maximal volume of air exhaled after a maximal inspiration, but without a forced effort
FEV6
The forced expiratory volume in 6 seconds-sometimes used as a surrogate for FVC
Spirometry measures what ??
the volume of air exhaled at specific time points during a forceful and complete exhalation after a maximal inhalation
Obtain FVC
Obtain FEV1
Obtain ratio (FEV1/FVC)
peak flow vs spirometry
peak flow is NOT a substitution for spirometry
Post-bronchodilator-performance of spirometry before and after bronchodilator
Determine the degree of reversibility of airflow limitation
Administration of albuterol if one suspects asthma or COPD
Spirometry interpretation
-FEV1/FVC is important for distinguishing obstructive airways disease and restrictive disease
A reduced FEV1/FVC ratio suggests ??
obstructive airway disease
A reduced FVC in combination with a normal or increased FEV1/FVC ratio suggests ??, if accompanied by reduced lung volumes
restrictive disease
charts
slide 11, 12, 13
PFTs:
sex, age, height predict lung values
comparing is not good enough need spirometry, pulmonologist consult
Flow-volume loops with maximal inspiratory and expiratory data can identify ??
upper airway obstruction, which can be undetectable with standard expiratory measurements
flow-volume loops used when?
When stridor is heard over the neck
Evaluation of unexplained dyspnea
Not sensitive for detecting a fixed upper airway obstruction
FV loops: A characteristic limitation of flow (ie, a plateau) during forced inhalation suggests ??
variable extrathoracic obstruction
see slide 16
Limitation of flow during forced exhalation suggests ??
variable intrathoracic obstruction
?? causes flow limitation during both forced inhalation and forced exhalation
Fixed upper airway obstruction
slide 17
FV curves
important to measure lung volumes when ??
gold standard?
when spirometry shows a decreased forced vital capacity (FVC)
- Body plethysmography is the gold standard*
- Chest radiograph or high resolution computed tomography (HRCT) correlate within 15 percent of those obtained by body plethysmography (can help)
The inspiratory reserve volume (IRV)
additional air that can be forcibly inhaled after the inspiration of a normal tidal volume
expiratory reserve volume (ERV)
additional air that can be forcibly exhaled after the expiration of a normal tidal volume
tidal volumes
-amountofexhalableair afterafullinspiration
Residual volume (RV)
air left in the lungs at the end of expiration
Inspiratorycapacity (IC)
maximumvolumethatcanbeinhaled (VT+IRV)
Functional residual capacity (FRC)
amount of air remaining in the lungs after normal expiration (RV+ERV)
Vitalcapacity (VC)
maximumvolumethatcanbeinhaledandexhaled(VT+ IRV+ERV)
Totallungcapacity (TLC)
entirevolumeofthelung (VT+IRV+ERV+RV)
?? are the key lung volumes for determining restriction
VC and TLC
VC and TLC values less than 5th percentile of predicted
Air trapping is indicated when ??
the FRC or RV is increased (>120 percent of predicted)
Hyperinflation is indicated when the ??
TLC is increased (>120 percent predicted)
The combination of an ?? both less than the fifth percentile lower limit of normal is considered a mixed defect
FEV1/FVC and TLC
Diffusing capacity: Measurement of the single-breath diffusing capacity for ?
carbon monoxide (DLCO, also known as transfer factor)
DLCO uses
Quick, safe, and useful in the evaluation of both restrictive and obstructive disease
In the setting of restrictive disease, the diffusing capacity helps distinguish between ??
intrinsic lung disease, in which DLCO is usually reduced, from other causes of restriction, in which DLCO is usually normal
slide 25
In the setting of obstructive disease, the DLCO helps distinguish between ??
emphysema and other causes of chronic airway obstruction
The six-minute walk test (6MWT) is a good index of physical function and therapeutic response in patients with ?
chronic lung disease, such as COPD, pulmonary fibrosis, or pulmonary arterial hypertension
not tested on
other submax exercise tests
incremental shuttle walk test (ISWT)
the endurance shuttle walk test (ESWT)
other PFTs: Measurement of maximal inspiratory and expiratory pressures; Indicated whenever ??
there is an unexplained decrease in vital capacity or respiratory muscle weakness is suspected clinically
Pulse oxygen saturation is an assessment of
of oxygen saturation can be used to identify a gas transfer defect and to titrate the amount of oxygen needed to maintain adequate oxygenation (should be hypoxemia)
-abnormally high with CO
ABG uses
Confirm hypercapnia
Provide a more accurate assessment of the severity of hypoxemia in patients who have low normal pulse oxygen saturation
-acid/base imbalances
-when someone looks v. sick; may need bipap, intubation
indications for pulmonary testing
- Evaluation of symptoms such as chronic persistent cough, wheezing, dyspnea, and exertional cough or chest pain
- Objective assessment of bronchodilator therapy
- Evaluation of effects of exposure to dusts or chemicals at work
- Risk evaluation of patients prior to thoracic or upper abdominal surgery
- Objective assessment of impairment or disability
- Monitoring disease course and response to therapy
chronic dyspnea
insidious, non-specific
When a diagnosis is needed within a day or two, a full set of PFTs may be ordered, often including spirometry before and after (pre- and post-) bronchodilator therapy, static lung volumes, and diffusing capacity
spirometry indications in asthma
- Spirometry before and after a bronchodilator is indicated during the initial workup of patients suspected of having asthma
- also indicated during most follow-up office visits to provide an objective measure of asthma control
COPD spirometry
-before and after an inhaled bronchodilator administration is the best method to detect or confirm airways obstruction in smokers with respiratory symptoms
COPD spirometry values ***
Values below 70 percent for the FEV1/FVC ratio and below 80 percent predicted for the FEV1 define airflow obstruction
The gold standard for measurement of total lung capacity (TLC), particularly in the setting of significant airflow obstruction, is ?
body plethysmography
Measurement of the ? helps to distinguish between emphysema and other causes of chronic airway obstruction
diffusing capacity for carbon monoxide (DLCO)
know GOLD criteria for COPD
slide 30
know spirometry section (not lung volumes, etc)
asthma and COPD have different
risk stratifications!!!
i.e. asthma responds to albuterol,
gold standard is used for COPD, asthma based on symptoms
Intrinsic lung diseases
cause inflammation or scarring of the lung tissue (interstitial lung disease) or fill the airspaces with exudate or debris (acute pneumonitis)
Extrinsic disorders
disorders of the chest wall or the pleura, which mechanically compress the lungs or limit their expansion
Neuromuscular disorders
which decrease the ability of the respiratory muscles to inflate and deflate the lungs
use spirometry and DLCO for restrictive ventilatory defects
slide 31
Spirometry is useful for determining the risk of postoperative pulmonary complications in certain high-risk situations, including patients known to have ?
COPD or asthma, current smokers, and those scheduled for thoracic or upper abdominal surgery
-Evaluation of patients being considered for lung resection begins with spirometry and DLCO
disability (FYI)
Constant severe dyspnea despite continuous treatment or intermittent extreme dyspnea despite continuous therapy FVC less than 50 percent predicted FEV1 less than 45 percent predicted DLCO less than 45 percent predicted VO2 max less than 15 mL/kg per min
in order to be COPD, need to have
obstruction
may have chronic bronchitis/emphysema WITHOUT having COPD
-many asthmatics do not have COPD, only if severe fibrosis/scarring
