Pulmonary Function Testing (Quiz 1).txt

• To identify and quantify changes in pulmonary function.
• To evaluate and quantify therapeutic effectiveness.
• Epidemiological surveillance for pulmonary disease.
• Assessment of postoperative pulmonary risk.
• To aid in the determination of pulmonary disability.

• The diaphragm and thoracic muscles must be capable of expanding the thorax and lungs to produce a subatmospheric pressure.
• The airways must be unobstructed to allow gas to flow into the lungs and reach the alveoli.
• The cardiovascular system must circulate blood through the lungs.
• Oxygen and carbon dioxide must be able to diffuse through the alveolar capillary membrane.

• NO.
• Other factors include:
• patient history
• physical examination
• chest x-ray
• arterial blood gas analysis

• Hemoptysis
• Pneumothorax
• Unstable cardiovascular (e.g., angina, BP problems, recent MI or pulmonary embolus)
• Thoracic, abdominal, or cerebral aneurysms
• Recent eye surgery (e.g., cataract)
• Presence of an acute disease process that might interfere with test (e.g., nausea, vomiting
• Recent surgery of thorax or abdomen

• 1. Specificity - most PF are not specific. Different disease may cause test to be abnormal (limitation). This explains why PFT test identify a pattern of impairment rather than diagnose a specific disease.
• 2. Sensitivity - some test are extremely sensitive or not sensitive.
• 3. Validity - each test must be valid to be meaningful. Ensuring pt effort/cooperation, equipment accuracy & calibration.
• 4. Reliability - consistency of the test. Test must be performed more than once

• Lung volumes and capacities
• Pulmonary (airway) mechanics
• Diffusion capacity of the lungs (DL)

• Tidal volume
• Inspiratory reserve volume
• Expiratory reserve volume
• Residual volume

• Total lung capacity
• Inspiratory capacity
• Functional residual capacity
• Vital capacity

• TV = 500 ml, 8-10% of TLC
• IRV = 3100 ml, 50-55% of TLC
• ERV = 1200 ml, 20% of TLC
• RV = 1200 ml, 20% of TLC

• IC = TV + IRV, 3600 ml, 60% of TLC
• VC = TV + IRV + ERV, 4800 ml, 80% of TLC
• FRC = ERV + RV, 2400 ml, 40%
• TLC = TV + IRV + ERV + RV, 6000 ml

• Tidal volume
• Inspiratory capacity
• Inspiratory reserve volume
• Expiratory reserve volume
• Vital capacity

• Residual volume
• Functional residual capacity
• Total lung capacity

• 1. Helium Dilution (closed-rebreathing circuit)
• 2. Nitrogen Washout (non-rebreathing or open circuit)
• 3. Body Plethysmography

• In healthy patients and those with small FRC, equilibrium occurs in 2 to 5 minutes
• Patient with obstructive lung disease may require up to 20 minutes
• FRC = (Vol He x FiHe) / FiHe - FfHe / FfHe

FRC, RV & TLC

• Similar to helium dilution, the time it takes to wash out the nitrogen is approx. 2 to 5 minutes in healthy patients
• longer in those with obstructive lung disease
• The test must occur in a leak-proof circuit, because the presence of air increases the measured nitrogen percentages and results in grossly elevated measurements of lung volume.

• Changes in lung volumes and capacities are generally consistent with pattern of impairement.
• TLC, FRC and RV increases in obstructive diseases and decreases with restrictive impairment. For example:
• TLC is always reduced in restrictive lung disease, unless obstruction and restriction occur together. Then the TLC may be a less sensitive measure of the restrictive impairment.

• An electronic controlled shutter near the mouthpiece allows the airway be occluded periodically, thereby measuring airway pressure changes condition of no airflow.
• pressure changes measured at the mouth are pressure changes in the alveoli

VC and IRV

decreased

• Forced vital capacity (FVC)
• Forced expiratory volumes (FEV) usually timed
• Forced inspiratory flow rates (FIF)
• Forced expiratory flow rates (FEF)
• Maximum voluntary ventilation (MVV)

• to assess the ability of the lungs to move large volumes of air quickly to identify airway obstruction.
• Some measurements are to check large airways and others for small airways

lower

• It is the maximum volume of gas that the patient can exhale as forcefully and as quickly as possible.
• This test can be done with simple spirometry

Forced Vital Capacity

• It is the maximum volume of gas that the patient can exhale during the first second of a FVC maneuver.
• This is an extremely useful test to determine between restrictive and obstructive

70 to 83% of FVC

94-97%

• compares the forced expiratory volume in 1 sec to its own forced vital capacity
• FEV1/FVC X 100
• Minimal value is approximately 70%

It is a Forced Vital Capacity where the graphic relationship between flows and resultant volume during a FVC and subsequent forced inspiratory volume maneuver.

central

peripheral

• The average flow rate of exhaled air after the first 200 ml during FVC maneuver
• It is a measure of the integrity and function of the large airways

6 to 7 L/sec (400 L/min)

obstructive lung disease and also those with severe restrictive disease

• The average flow rate during the middle portion of the FEV
• It is a measure of the middle 50% of the expiratory flowrate.

airway function

4 to 5 L/sec

independent

decreased

• The maximum volume of air moved into and out of the lungs voluntarily 10, 12, or 15 sec.
• It is an index of the integrity and function of the lung-thorax relationship

the airway resistance (obstructive), status of the respiratory muscles (weakness), integrity of the lung parenchyma and thorax (compliance)

150 to 200 L/min. for males

dependent

air trapping

• Peak Expiratory Flow
• It is usually at the early part of exhalation

in home care and for trending to determine increasing bronchospasm

400 to 600 L/min (male), 300 to 500 L/min (female)