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