Flashcards in Pulmonary Function Tests Deck (56)
Assessing the functional status of the lungs as it relates to:
1. How much air volume can be moved in and out of the lungs
2. How fast the air in the lungs can be moved in and out
3. How stiff the lungs and chest wall are - a question about compliance
4. The diffusion characteristics of the membrane through which the gas moves (determined by special tests)
5. Measurement of how the lungs have responded to treatment
Indications for PFT?
1. Screening for lung disease in patients with symptoms
2. Following the progression of pulmonary disease - restrictive or obstructive
3. Evaluating the effectiveness of therapeutic intervention
4. Evaluating the patient prior to certain types of surgery:
5. Objective assessment of impairment or disability
Evaluating the patient prior to certain types of surgery is an indication for PFTs. What would this help us with? 4
What kind of patients would benefit from this evaluation?? 3
1. risk for postoperative respiratory complications
Reflects the patient's ability to
2. take a deep breath,
3. to cough, and
4. to clear the airways of excess secretions
COPD, CHF, Do they have enough pulomnary reserve to get them off the ventilator?
Types of Pulmonary Function Tests?
Measurement of lung volumes
Quantification of diffusion capacity
Oxygen uptake (VO2)—exercise capacity
What does spirometry measure?
1. Forced expiratory volume in one second (FEV1)
2. Forced vital capacity—(FVC)
Most readily available and most useful PFT
$1,500 – $2,500
Definition of spirometry?
(What does it assess?)
Spirometry with flow volume loops assesses the mechanical properties of the respiratory system by measuring expiratory volumes and flow rates
(how much they can inhale and exhale and how fast they can do it)
Flow volume loops provide what?
How is the chart plotted?
a graphic illustration of a patient's spirometric efforts
flow against volume
The normal volume time curve for spirometry is shaped how?
The maximum volume attained represents what?
while the volume attained after one second represents what?
has a rapid upslope and approaches a plateau soon after exhalation
the forced vital capacity (FVC),
the forced expiratory volume (FEV1)
Variables that might affect a spirometry test?
Body height and size
Why would age change the PFT?
Why would gender affact the PFT?
How does race affect PFTs?
1. The natural elasticity of the lungs decreases
2. This translates into smaller and smaller lung volumes and capacities as we age
1. Usually the lung volumes and capacities of males are larger than the lung volumes and capacities of females.
2. Even when males and females are matched for height and weight, males have larger lungs than females.
1. Blacks, Hispanics and Native Americans have different PFT results compared to Caucasians
If person becomes too obese how will this affect the PFT?
the abdominal mass prevents the diaphragm from descending as far as it could and the PFT results will demonstrate a smaller measured PFT outcome
What are some examples of obstructive disorders?
3. Excessive mucus plugging
4. foreign object inhalation
5. invasive tumors
1. "Restriction" in lung disorders always means a what?
2. This term can be applied with confidence to patients whose total lung capacity has been what?
3. What is total lung capacity?
4. Why cant TLC be measured by spirometry?
5. TLC is the summation of what?
1. decrease in lung volumes
2. measured and found to be significantly reduced
3. Total lung capacity (TLC) is the volume of air in the lungs when the patient has taken a full inspiration.
4. because air remains in the lungs at the end of a maximal exhalation - i.e. the residual volume or RV
5. The TLC is therefore the summation of FVC + RV
What are the ways you can measure TLC?
1. Helium dilution
2. Nitrogen washout
3. Body plethysmography (gold standard)
4. Chest radiograph or HRCT measurements
Neuromuscular Restrictive lung Disorders
1. Generalized Weakness – malnutrition
2. Paralysis of the diaphragm
3. Myasthenia Gravis
4. Muscular Dystrophy
6. Amyotrophic Lateral Sclerosis
Intrinsic Restrictive Lung Disorders?
1. Scoliosis, Kyphosis
2. Ankylosing Spondylitis
3. Pleural Effusion
5. Gross Obesity
8. Pain on inspiration
--Pleurisy, rib fractures
What is FEV1?
forced expiratory volume in1sec:
the volume of air that is forcefully exhaled in one second
It is 75% of FVC
What is FVC?
forced vital capacity
the volume of air that can be maximally forcefully exhaled
NOT the TLC
What is the FEF 25-75%?
What does it measure?
the average forced expiratory flow during the mid (25 - 75%) portion of the FVC
measures of the flow rate in liters per second of the middle half of a FVC test
Why do we want to look at the middle half of the forced expiratory flow?
The first quarter is effected by the patients effort in overcoming the inertial forces which resist thoracic wall expansion
The last quarter is polluted by the pts dimishing physical effort in instigation of bronchospasm during forced expiration and the breathlessness associated with the terminal completion of a FVC test.
What is FEF 25%-75% a senstive test for?
obstructive airway disease
What is PEFR?
What does it measure?
The peak expiratory flow rate (PEFR) during expiration
Peak Expiratory Flow Rate (PEFR) is a measure of the highest expiratory flow rate during the PFT test
What is PEFR best used for?
Patients with a low PEFR would have to be further evaluated for obstructive pathologies
A useful measure to see if treatment is improving obstructive disease (like bronchoconstriction in asthma)
What is TLC?
Total lung capacity (TLC): The volume in lungs at maximum inspiration
What is VC?
Vital capacity (VC): The maximum volume expired after a maximum inspiration
What is TV?
Tidal volume (TV): The volume inspired and expired during normal breathing
What is RV?
Residual volume (RV): The volume left in the lungs after maximal expiration
What can lung volumes only be measured with?
body plethysmography (body box)