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What can PFTs measure?
- Flow rates
- Lungs volumes & capacities
- Alveolar Gas diffusion
- Lung muscle function
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What is "VC"?
Vital Capacity - volume of air that can be expelled from fully inflated lungs after full inspiration
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What is FVC?
- Forced Vital Capacity
- Vital capacity with exhalation done at max effort
- decreased in restrictive & severe obstructive
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What is VT?
Tidal Volume - Volume of air that enters the lungs during normal inspiration and leaves during normal expiration
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What is FRC?
Functional residual capacity - volume of air remaining in the lungs after completion of a normal exhalation
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What is ERV?
Expiratory Reserve volume - volume of air that can be exhaled following a normal expiration
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What is RV?
- Residual Volume - the volume of air remaining in the lung after a forced exhalation
- decreased in restrictive
- increased in obstructive
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What is TLC?
- Total Lung Capacity - Total volume of air in the lungs after full inhalation
- decreased in restrictive
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What is IC?
Inspiratory Capacity - Maximum volume of air that the patient can inhale from a resting level
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What is IRV?
Inspiratory reserve volume - Volume of air that can be inspired above normal inhalation
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What is FEV1?
- Forced expiratory volume in one second
- decreased in obstructive
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What is FEF?
- Expiratory Flow Rate - Flow rate during the forceful exhalation of the middle half of the FVC maneuver
- decreased in early obstructive and small airways
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What is FEV1%?
- Percent of FVC exhaled during first second
- decreased in obstructive
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What is Peak Flow?
- Maximal flow rate that can be achieved during expiration
- not usually reported on spirometry
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What are the indications for a PFT?
- Evaluate pulmonary sx (cough, dyspnea, wheeze)
- Screen for pulmonary disease in high risk for early detection
- Monitor Pulmonary disease (response to therapy, progression)
- Pre-Op eval
- Legal & Disability determination
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What are some contraindications for PFT?
- Severely debillitated person
- Dementia
- acture respiratory distress
- Unstable angina
- recent eye, abdominal, or thoracic surgery
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What is the PFT preparation?
- No taking SABA for 6 hours
- No taking LABA for 48 hours
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What is the FVC maneuver?
- Breath normally (3 resting breaths)
- Take full inspiration
- exhale hard, fast, completely and continuous for 6 seconds or obvious plateu
- Repeat twice until 3 acceptable tracings
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What is a DLco?
Diffusion capacity - ability of gas to diffuse through alveoli
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What is the Gold Standard test for reversible obstructive symptoms?
Methacholine Challenge Test - makes you spasm
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What are the indications for ordering a FULL PFT?
- Restrictive Pattern on spirometry
- Severe obstructive pattern on spirometry
- Mixed pattern on spirometry
- Inconsistent test or H&P results
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What are examples of obstructive diseases?
- Asthma
- Emphysema
- Chronic bronchitis
- bronchiectasis
- cystic fibrosis
- Fixed & variable upper airway disease
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What are examples of Restrictive disease?
- Interstitial lung disease
- Skeletal and Body
- Pregnancy
- Neuromuscular
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What are the levels for obstructive disease?
- Mild - >70%
- Moderate - 60-69%
- Moderately severe - 50-59%
- Severe - 35-49%
- Very severe - <35%
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What are the levels of restrictive disease?
- Normal - >80%
- Mild - 70-79%
- Moderate - 50-69%
- Severe - <50%
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What are some diffusion capacity patterns?
- Decreased in disease that effect alveoli
- emphysema w/decrease SA
- pulmonary fibrosis w/increased thickness
- can be increased in asthma and pulmonary edema
- False positve with anemia
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What are patterns that can be found in an obese patient?
- Decreased Total lung capacity
- Decreased SVC
- Decreased MVV
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