Pulmonary Function Test Flashcards
Pulmonary Function Tests
Description
A group of tests which help evaluate the mechanical function of the lungs
Patient results are compared to predicated values to determine if the patient falls within normal range, or has a restrictive or obstructive lung disease based on the PFTs
PFT: Clinical Utility
(4)
- Determine if patient’s presents with a respiratory condition
1. Obstructive (resistance to getting air OUT)
2. Restrictive (resistance to getting air IN)
3. Combination of both - Determine the severity of respiratory condition
- Determine response to bronchodilator treatment (does respond = asthma)
- Outcome measure (pre-post test) to determine disease progression, effectiveness of treatment & medications
Categories of PFTs
(5)
- Volume
- Capacity
- Flow
- Diffusion studies
- Respiratory mm strength
Static Lung Volumes
(4)
Volume
- Tidal Volume (TV)
- Inspiratory Reserve Volume (IRV)
- Expiratory Reserve Volume (ERV)
- Residual Volume (RV)
Tidal Volume (TV)
Definition
Volume
The volume of air inhaled or exhaled during a single breath in a resting state (normal quiet breathing)
In & out during a QUIET breath
Inspiratory Reserve Volume (IRV)
Defintion
Volume
The maximum amount of air that can be inhaled following a normal inspiration
Expiratory Reserve Volume (ERV)
Definition
Volume
The maximum amount of air that can be exhaled following a normal exhalation
Residual Volume (RV)
Definition
Volume
The volume of air remaining in the lungs at the end of maximum expiration (cannot exhale it)
Nitrogen has helps keep our lungs inflated - residual volume
** Always going to have air remaining in lungs b/c it prevents the lungs from collapsing
Volume: DDx
(4)
Volume
Tidal Volume
- DEC TV = restrictive disease, lung cancer, atelectasis, msk impairment (all fall under restrictive diseases)
Residual Volume
- INC RV = obstructive disease
- DEC RV = restrictive disease, lung cancer, atelectasis, msk impairment
Inspiratory Reserve Volume:
INC IRV = obstructive
DEC IRV = restrictive
Expiratory Reserve Volume:
DEC ERV = pleural effusion, pneumothorax, ascities (S/S of RT HF - edema in the belly)
Restrictive diseases relating to the pleura
What is the main characteristic of obstructive disease in terms of volume??
Every component increases EXCEPT tidial volume
INC TLC, RV, IRV, ERV
Capacity:
Descrip & List
Lung capacities = 2+ lung volumes together
- Total Lung Capacity (TLC)
- Vital Capacity (VC)
- Inspiratory Capacity (IC)
- Functional Residual Capacity (FRC)
Volume = single entity // Capacity = 2+ vol
Total Lung Capacity (TLC)
Description
Capacity
The volume of gas in the lungs at the end of maximum inspiration
TLC = TV + IRV + ERV + RV
Vital Capacity
Definition
Capacity
The maximum amount of gas that can be expired from the lungs following a maximum inspiration
VC = TV + IRV + ERV
Inspiratory Capacity (IC)
Definition
Capacity
The maximum amount of gas that can be inspired from the resting expiratory level
IC = VT + IRV
Functional Residual Capacity (FRC)
Definition
Capacity
The amount of gas remaining in the lungs at the resting expiratory level
FRC = ERV + RV
Capacity: DDx
(2)
INC capacity = obstructive
DEC capacity = resistrictive
Flow
Definiton + Types (2)
Flow
Rate - how long does it take to move that air
- Forced Vital Capacity (FVC)
- Forced Expiratory Volume (FEV)
Forced Vital Capacity
Definition
Flow
The total lung volume of air that can be expired after a maximal inhalation
Independent of time
Will still have RV
Forced Expiratory Volume (FEV)
Definition
Flow
The maximum volume of air that can be expired from maximal inhalation in “x” seconds
Dependent of time
FEV1/FVC%
Defintion
Flow
The percent of FVC that can be expired in 1 second
< 70% = obstructive disease Diagnostic
- Lots of resistance to get that air out
Flow: DDx
(2)
Flow
Condition > FVC > FEV1 > FEV1/FVC%
Obstructive > Normal or low > Low > Low
Restrictive > Low > Normal or Low > Normal or high (does not take a lot of time to force air out)
GOLD Classification for COPD
(4)
Gold Classification > FEV1/FVC(%) > FEV1 % Predicted
- Mild > < 70% > FEV1 > 80% predicted
- Moderate > < 70% > FEV1 50%-80% of predicted
- Severe > < 70% > FEV1 30-50% of predicted
- Very Severe > < 70% > FEV1 < 30% of predicted OR
- FEV1 < 50% predicted + chronic respiratory failure (long-term O2 supplementation)
Diffusion Studies
Definition & Types + Descripts
Diffusion Capacity of Carbon Monoxide (DLCO)
- Test that measure the functioning gas exchange from the lungs (alveoli) to the blood (pulmonary capillary bed)
- Helps diagnosis different pathologies
LOW DLCO: could be a problem with pulmonary or circulatory system
- Ex. Emphysema, fibrous, anemia
HIGH DLCO: Problem with circulatory system, NOT pulmonary (rule out)
- Ex. polycythemia (opposite of anemia) - makes your blood thick/vicous > takes up the CO2 immediately - difficult to pump - hard on the heart
Respiration MM Strength Tests
2 Types
Maximal Inspiratory Pressure (MIP)
- Patient attempts a maximal inspiratory effort through a blocked mouthpiece
- A patient’s MIP reflects the strength of the patient’s inspiratory mms
Maximal Expiratory Pressure (MEP)
- Patient attempts a maximal forced expiratory effort through a blocked mouthpiece, after a full inhalation
- A patient’s MEP reflects the strength of the patient’s expiratory mm
Respiration MM Strength Tests: Indications
(3)
- When respiratory weakness is suspected
NM condition, dyspnea, ineffective cough - When prescribing an inspiratory muscle trainer (IMT)
= Max pressure - set parameters accordingly - Outcome measure for respiratory mm strength
Can see if they have gotten stronger OR if disease has progressed
Regular expiration is PASSIVE
Cough = forced expiration
