Pulmonary Function Tests Flashcards
List some indications for PFTs
- to assess disease in a pt with risk factors
- to evaluate symptoms in chronic disease
- to assess bronchodilator therapy effectiveness
- to assess effects of occupational exposure
- to assess risk prior to surgery (upper abdominal or thoracic)
List a few contraindications to PFTs
- severe debilitation
- mod-severe resp disease
- pt not able/willing to provide full effort
- young kids (less than 5)
What does a PFT tell you
- if there is lung pathology
- severity of lung dysfunction
- is a treatment working
- has a disease progressed
List a few things that a PFT can help diagnose
- asthma
- COPD
- differentiate obstructive vs restrictive patterns
Define an obstructive pattern
difficulty getting air out of the resp system (typically occurs in smaller airways)
- FBA, tumor, chronic mucus, CF, airway thickening, etc
Define a restrictive pattern
volume capacity and difficulty getting air in
- ILD, stiff chest, resp muscle weakness
What is pulse oximetry for
asses available oxyhemoglobin in a patient
What does a peak flow meter do
helps define the capacity to expel air from the lungs
- measures maximum speed of expiration
- can be used by pt, usually to follow asthma triggers
Define total lung capacity
volume of lung for all phases of respiration
Define tidal volume
lung volume representing the normal volume of air displaced between normal resting inhalation/exhalation
Define reserve volume
additional air that can be forcibly inhaled or exhaled after normal tidal volume
define residual volume
amount of air remaining in the lungs after full expiration (can’t be directly measured)
define vital capacity
amount of air that can be forcibly inhaled and exhaled
Define Forced Expiratory Volume (FEV1)
max volume of air that can be exhaled in the first second of a forced exhalation following inspiration (expressed in liters)
Define FEV1/FVC
calculated ratio that helps differentiate obstructive and restrictive patterns
Define forced vital capacity
total volume of gas that can be forcefully exhaled after a full inspiration (liters/second)
Define spirometry
- measures exhaled/inhaled volumes
- follow effectiveness of asthma/COPD management
What is normal FVC
> 80%
What FVC shows a restrictive pattern
<80%
can be reduced by suboptimal pt effort, airflow limitation, neuromuscular process, restrictive lung dz
what is the most important spirometry variable for assessing severity of disease
FEV1
What is the normal FEV1/FVC ratio for adults vs kids
Adults: >70%
Kids: >85%
What FEV1/FVC ratio indicates an obstructive pattern
<70%
what is this pattern
normal
what is this pattern
obstructive
What is this pattern
fixed obstruction (chest wall injury)
What is this pattern
variable extrathoracic
What is this pattern
variable intrathoracic (pneumothorax)
what is this pattern
restrictive
define diffusing capacity (DLCO)
- measure of a single breath to evaluate obstruction/restriction severity
- low DLCO indicates oxygen therapy
- IP or occupational
- not used in COPD following
What is a normal DLCO measure
20-30 ml/mn/mmHg
What may a low DLCO indicate
- emphysema
- bronchiectasis
- ILD
- pulmonary vascular disease
- neuromuscular dz
What does a high DLCO indicate
- polycythemia
- pulmonary hemorrhage
- exercise, L to R cardiac shunting
- maybe asthma, bronchitis, obesity
An increase in FEV1 by more than what indicates a reversible pattern when given a bronchodilator
12%
