Pulmonary Function Tests Lecture Powerpoint Flashcards
2 functions of the sinuses and how do we learn to breath first?
- Lighten the weight of the head
- Moisten and filter air
-through the nose
Because of the respiratory system’s ability to filter upon inspiration, most pneumonias are the result of…
….reflux and aspiration
Further down in the respiratory tract, we see more smooth muscle and less cartilage tissue making it….
…more capable of partial collapse or complete collapse in disease states (this increases residual volume in the lungs as everything distal to the collapse is affected)
Functions of PFT’s (3)
- add to diagnosis of disease (pulmonary and cardiac)
- monitor progression of disease and effectiveness of treatment
- aid in pre op assessment of certain patients
Different components of PFTs (8)
- spirometry
- flow volume loop
- bronchodilator response
- lung volumes
- diffusion capacity (DLCO)
- bronchoprovocation testing
- max respiratory pressures
- simple and complex cardiopulmonary exercise testing
6 min walk test
Test to evaluate physical function or assess therapeutic response in COPD and pulmonary fibrosis patients, considered positive if oxygen saturation falls by >4% ending below 93% after 6 minutes of walking and indicates need for confirmatory ABG’s
Indications for PFTs (6)
- Signs and symptoms of pulmonary distress
- screening at risk population (smokers current or former >45 years of age)
- monitoring drug toxicity
- abnormal study such as CXR or EKG
- environmental exposure monitoring
- preoperative assessment and risk stratification
PFT’s are beneficial but…
….they only support or exclude a diagnosis
Steps to performance of an FVC maneuver in spirometry
- Prep patient (results are VERY effort dependent)
- cover nose with clip
- elevate chin slightly and extend neck slightly
- put mouthpiece in mouth after inhaling and then exhale hard and fast as possible
- need to avoid coughing, variable flow, or early termination
Spirometry’s goal is to measure ____, it cannot (directly) measure ____
Vital capacity, residual volume
Body plethysmography
Used to measure total lung capacity by placing patient in a small airtight room while taking measurements to determine residual volume and total lung capacity
Flow (flow volume loop) definition
Volume of a substance moved thru a structure or space over a period of time in L/s
Flow volume loop, what is it sometimes referred to as?
- A measurement of flow during pulmonary function testing that should have a rounded inhalation and a sharp spike in expiration (this height should represent 90% of what can be exhaled) followed by continuous drop straight line
- also referred to as a spirogram
Volume time loop
A measurement of flow during pulmonary function testing that determines FEV1 and should have 90% of the volume (in L) released in the first second before quickly tapering off to a flat line
Lung properties that affect spirometry (2)
- mechanical properties (compliance and elastic recoil)
- resistive properties (affected by airway diameter predominantly)
% predicted in spirometry
What a patient performed based on what is predicted based on age, gender, height, weight, ethnicity to determine some fraction value which is then interpreted (low % is worse for the patient)
Spirometry % FVC predicted value interpretation
80-120% normal
70-79% mild reduction
50-69% moderate reduction
<50% severe reduction
Spirometry % FEV1 predicted value interpretation
> 75% normal
60-75% mild obstruction
50-59% moderate obstruction
<49% severe
Spirometry % FEF 25-75% predicted value interpretation
> 60% normal
40-60% mild
20-40% moderate
<10% severe
Obstructive disease pattern loss with spirometry % predicted values
- FEF 25-75 decreased
- FEV1 decreased
- FVC normal to decreased in late stage (last thing to go)
- FEV1/FVC <70% predicted
Obstructive lung disease list (5)
- asthma (reversible obstructive dz)
- COPD (chronic bronchitis and emphysema)
- bronchiectasis
- bronchiolitis
- upper airway obstruction
Restrictive disease pattern loss with spirometry % predicted values
- TLC decreased
- FVC decreased
- Normal or increased FEV1/FVC ratio
Restrictive lung disease list (4)
- Parenchymal disease (interstitial lung disease)
- pleural disease
- chest wall disease
- neuromuscular disease
Scooped out vs witch’s hat on volume/flow diagram
Scooped out is characteristic of obstructive disease, witch’s hat is characteristic of restrictive disease
Bronchodilator response spirometry
Test done on patients with obstructive pattern on spirometry to determine degree to which FEV1 improves with inhaled bronchodilator to document reversible airflow obstruction, significant if FEV1 increases by 12% and 200mL or greater
Fixed upper airway obstruction pattern on flow volume loop (such as a tumor in larynx) vs variable extrathoracic obstruction vs variable intrathoracic obstruction
- Rounded shape with equal expiratory (+) and inspiratory (-) values
- Rounded shape with greater expiratory (+) and lower inspiratory (-) flow
- Rounded shape with lower expiratory (+) and greater inspiratory (-) flow
- Methods for measuring lung volumes (3)
- Indications for a lung volume measurement (2)
- Helium, nitrogen washout, body plethsmography
- diagnose restrictive component, differentiate between chronic bronchitis from emphysema
Lung volume % predicted patterns (TLC and RV) in obstructive and restrictive disease
Obstructive: TLC>120% predicted, RV >120% predicted
Restrictive: TLC <80% predicted, RV <80% predicted
Carbon monoxide diffusion capacity (DLCO), what does a decreased and increased value mean?
- Measures the lungs diffusing capacity to transport inhaled gas from alveoli to pulmonary capillaries using a small amount of carbon monoxide
- <80% predicted indicates obstructive lung disease or anemia, >120% predicted indicates asthma or polycythemia
7 barriers to o2 transport in the alveoli according to walt
- alveolar epithelium
- tissue interstitum
- capillary epithelium
- plasma layer
- red cell membrane
- red cell cytoplasm
- hemoglobin binding forces and type of hemoglobin
Bronchoprovocation testing, what is a positive result?
Use of methacholine, histamine, or exercise stress test in an attempt to induce bronchospasm useful in diagnosis of asthma and diagnostic if >20% decrease in FEV1
Obstructive pattern evaluation of FVC. FEV1, FEV1/FVC, FV loop shape, DLCO, TLC/RV, responsiveness to bronchodilator
- FVC normal or decreased
- FEV1 decreased
- FEV1/FVC decreased <70%
- scooped loop
- DLCO decreased in emphysema or normal in crhonic bronchitis
- TLC/RV increased
- positive response to bronchodilator
Restrictive pattern evaluation of FVC, FEV1, FEV1/FVC, FV loop shape, DLCO, TLC/RV
- FVC decreased
- FEV1 decreased or normal
- FEV1/FVC normal
- witch’s hat loop
- DLCO decreased
- TLC/RV decreased
DLCO will be ___ in emphysema but ___ in chronic bronchitis because ____
Decreased, normal, chronic bronchitis affects proximal airways where gas exchange is not taking place
Acinus
The anatomic unit of the lung supplied by the terminal bronchiole where gas exchange in the respiratory system occurs
Principle of child lung function preservation
Need to preserve while young so it continues to have sufficient reserve when old
The 4 volumes of the lung
- Inspiratory reserve
- tidal
- expiratory reserve
- residual
The 4 capacities of the lung
(2 or more volumes comprise a capacity)
- vital
- inspiratory
- functional residual
- total lung
FEV1
Forced expiratory volume in 1 second, a very beneficial measurement taken by spirometry
FVC
Forced vital capacity, a very beneficial measurement taken by spirometry
FEV1/FVC%
The forced expiratory volume in one second divided by the total forced vital capacity, should be 90% in a healthy lung, a very beneficial measurement taken by spirometry
FEF25-75
Measure of forced expiratory flow during middle have of FVC, provides insight into the smaller and intermediate airways and indicates treatment being necessary as early stages of lung disease progresses before other spirometric values are decreased as well
____ spirometry measurement is used to track severity of COPD over time
FEV1
Normal lungs have ___ flow rate and ___ lung volume
Restrictive lungs have ___ flow rate and ___ lung volume
Obstructive lungs have ___ flow rate and ___ lung volume
- High, high
- High, low
- Low, high
Bronchoprovocation is useful in diagnosis of asthma in the setting of ____ PFTs
Normal
