Unit 6- PFT and Thoracic Imaging Flashcards
How can you determine a restriction?
Look at the TLC, VC, FRC, or RV depending on what is given. 80-120% is normal.
Mild is 70-79% or 121-130%
Moderate is 50-69% or 131-150%
Severe is 150%
How can you tell if a PFT is obstructive?
Look at the FEV1/FVC ratio. Normal is 80-120%. If less than 70, it is obstructed.
Mild is 70-80%
Moderate is 50-70%
Severe is <50%
What makes up TLC?
VC + RV … IC + FRC
or
IRV + TV+ ERV + RV
What makes up VC?
IRV + TV (or VT) + ERV
What are indications for spirometry?
ID and quantify changes in pulmonary function.
Evaluate need and quantify therapeutic effectiveness
Perform epidemiological surveillance for pulmonary disease
Assess patients for risk of postoperative pulmonary complications
Determine pulmonary disability
Contraindications for spirometry
Patients with acute, unstable cardiopulmonary problems (hemoptysis, pneumothorax, MI, PE, acute CP, or AP)
Nausea or vomiting- pt may aspirate
Recent cataract surgery- increased intraocular pressure
If reliable results will not be obtained (pt effort, dementia, confusion)
Test specificity
Several diseases may cause a result to be abnormal. This shows a pattern of impairment rather than diagnosing a specific disease.
Sensitivity
How sensitive is the test? Some healthy people may appear sick. Sick people may not test ill, causing extremely sick people to show an abnormal result.
Validity
Ensures the test measures what it was intended to measure. Examples include following test procedures, ensuring patient effort or performance, and ensuring equipment accuracy and calibration.
Reliability
This is the consistency of the test results. This will produce consistent results with minimal variability.
Accuracy
How well a device measures a reference value
Capacity
Range or limits of a device on how much it can measure
Error
Arithmetic difference between reference value and measured value
Precision
Reliability of the measurements
Resolution
The smallest detectable measurement. High resolution can measure small values, flows, or times.
Linearity
Accuracy of the measurement over its entire range (capacity)
Minimum FVC that healthy people exhale in the first second?
70% from the quiz. However HEALTHY people typically exhale 83%
Measurements of pulmonary mechanics?
Pulmonary mechanics assesses the ability of the lungs to move large volumes of air quickly through airways to ID airway obstruction.
FVC, FEV1, FEF, forced inspiratory flow rates, MVV
Bronchial challenge test
An agent stimulates a hyper reactive airway response to create obstruction. Methacholine is preferred. You start at .03 then double dose until a positive response is observed (or until you reach 16 mg.) Looking for a FEV1 decrease of at least 20%
Normal tidal volume
500 mL
Normal inspiratory reserve volume
3100 mL
Normal expiratory reserve volume
1200 mL
Normal residual volume
1200 mL
Normal TLC
6000 mL