Term
| Primary function of the respiratory system is to maintain normality of arterial blood gases (PaO2 and PaCO2) through: |
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Definition
- Alveolar ventilation
- Pulmonary perfusion
- Gas transfer across alveolar-capillary membrane
- Ventilation-perfusion matching
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Term
| Procedures for PFT: Arterial Blood Gases |
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Definition
- pH and pCO2 are most important
- pO2 -- pulse oximeter is most accurate way to get oxygen saturation
- HCO3-
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Term
| Procedures for PFT: Carbon Monoxide Diffusion Capacity (DLCO) |
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Definition
- Marker of gas diffusion across the alveolar-capillary membrane
- Reduced in situations where impairment of gas transfer exists (COPD, Interstitial lung disease)
- Can differentiate between astham and COPD
- Not clinically used -- too expensive, not practical
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Term
| Procedures for PFT: Gas Dilution or Washout Technique |
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Definition
- Either closed circuit helium dilution or open-circuit nitrogen washout to measure lung volume
- Extrapolates lung volumes - what comes in vs what comes out
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Term
| Procedures for PFT: Body Plethysmography |
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Definition
AKA Body Box
- Can get any lung measure you could possibly want!
- Patient sits in chamber and pressure is manipulated
- Important test for total lung capacity
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Term
| Procedures for PFT: Peak Expiratory Flow (PEF) |
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Definition
- Same as Peak Flow Meter
- Maximal level on forced expiration
- Not for diagnosis
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Term
| Procedures for PFT: Spirometry |
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Definition
- Most clinically useful for diagnosis and monitoring
- Measurement of the movement of air into and out of the lungs during various breahting maneuvers
- Measures Vital Capacity, Inspiratory Reserve Volume, Tidal Volume, and Expiratory Reserve Volume
- Residual Volume MUST BE calculated
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Term
| Inspiratory Reserve Volume |
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Definition
| Amount of air inhaled over and above normal tidal volume after a normal tidal inspiration |
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Term
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Definition
| Volume of air inhaled or exhaled during normal breathing |
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Term
| Expiratory Reserve Volume |
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Definition
| Amount of air that can still be expired by forceful expiration after the end of a normal tidal expiration |
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Term
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Definition
- Volume of air remaining in the lungs at the end of the maximal exhalation
- Must be calculated
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Term
| Obstructive Pulmonary Diseases: Effects on Spirometry Volumes |
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Definition
IRV - decreased
TV - same to increased
ERV - decreased
RV - increased
IC - decreased
FRC - increased
VC - decreased
TLC - same, sometimes increased
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Term
| Restrictive Pulmonary Diseases: Effects on Spirometry Volumes |
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Definition
IRV - decreased
TV - same to decreased
ERV - decreased
RV - decreased
IC - decreased
FRC - decreased
VC - decreased
TLC - decreased
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Term
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Definition
| The VC performed at maximal efforts |
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Term
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Definition
- Measured after maximal inhalation then exhalation
- Results in a flow volume curve
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Term
| Forced Expiratory Volume in 1 second |
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Definition
- Amount of air moved over 1 second (most important for PFT)
- Used to diagnose most obstructive pulmonary disease
- Used to predict response to bronchodilators
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Term
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Definition
- Term used to describe the graph resulting from plotting the FVC against the FEV1
- FEV1 should be at least 75-80% of FVC -- if not, some obstructive disease exists
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Term
| The most sensitive way to measure obstruction is: |
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Definition
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Term
| Characteristics of Flow Volume Curve: Obstructive |
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Definition
Shape - Concave
FVC - Same
FEFmax - Same
FEV50 - Increase |
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Term
| Characteristics of Flow Volume Curve: Restrictive |
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Definition
Shape - Convex or "same"
FVC - Decreased
FEFmax - Same or decreased
FEV50 - Decreased |
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Term
| Restrictive Defect vs Obstructive Defect |
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Definition
Restrictive
- Overall decrease in lung volumes without reduction in airflow
- Hallmark: reduction in TLC
- Decreased VC may also be seen and is sometimes more clinically useful
Obstructive
- Reduction in airflow through the conducting airways due to a decrease in diameter, loss of integrity, or reduction in elastic recoil
- Hallmark: reduction in FEV1
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Term
| Diseases Associated with Obstructive Defect |
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Definition
- Asthma
- COPD
- Presence of tumor or granuloma
- Presence of foreign body that mechanically obstructs bronchi
- Bronchiolitis
- Cystic Fibrosis
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