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
Normal IC inspiratory capacity
3600 mL
Normal FRC functional reserve capacity
2400 mL
Normal vital capacity
VC
4800 mL
What does a normal flow volume loop look like?
A m-fin’ BOX. Thanks Vines, thanks a lot.
What does an extrathoracic upper airway obstruction look like?
A cone head
HAHA
What does an intrathoracic upper airway obstruction look like?
An iceberg…
The lower part (inspiration) is larger
A significant pre/post bronchodilator result is apparent when…
FEV1 increases 12-15%
AND
an increase in at least 200 mL is observed for FEV1
Helium dilution
used to measure FRC. RV is calculated by FRC- ERV
Nitrogen washout
Used to measure FRC. Similar technique to helium dilution.
Plethysmography
Used to measure FRC. This applies Boyle’s law and uses measurements of pressure and volume.
Gas used to measure diffusing capacity of the lung
CO
carbon monoxide
DLCO reduction?
Reduced in patients with obstructive or restrictive lung diseases.
Anemia, carboxyhemoglobin, pulmonary embolism, diffuse pulmonary fibrosis, pulmonary emphysema.
Increase DLCO?
Polycythemia
Exercise
CHF
Indications for chest radiograph
Unexplained dyspnea, severe cough, hemoptysis, fever and sputum production, acute severe CP, + TB skin test
Placement of ETT, placement of artery catheter, placement of central venous pressure catheter, sudden dyspnea or CP, elevated or changing plateau pressure during mechanical ventilation, sudden decline in oxygenation
Tissue densities seen on chest radiograph
air
fat
soft tissue
bone
Radiolucent
Appears black on film
Radiopaque
Appears white on film
Evaluating the technical quality of a chest radiograph?
ID the name.
Is it centered? Is the penetration of the beam too high or too low? Review the anatomical structures to assess normality or abnormality.
PA chest film
Beam first penetrates back, then chest, then film. The patient must be standing. This will minimize the magnification of the heart.
AP film
The beam passes through the chest, then back, then to film.
Patient is typically laying down.
The heart is slightly magnified!!!
Computed tomography (CT)
Visualize structures in cross section and can visualize great detail and minuscule structures.
Areas such as mediastinum, apices and costophrenic sulci, and pleural surfaces are easily seen.
High Rez CT
Used to evaluate the lung parenchyma using thin-slice images
CT angiography
Contrast dye is injected into the patient.
The tech waits until the contrast material has entered the area to be studied.
Excellent at identifying pulmonary thromboemboli. Can also look at the coronary artery.
MRI
Good at visualizing vascular structures.
Mediastinum, large vessels in the lung, and hilar regions are most commonly imaged.
Ultrasound US
High frequency sound waves are echoed off of tissues in the body. Excellent at evaluating heart or pleural fluid. Also used to place central or arterial catheters.
Common pleural abnormalities
Hydrothorax
Pneumothorax
Common lung parenchyma abnormalities
Alveolar disease Pulmonary edema Interstitial disease Atelectasis Solitary pulmonary nodule
Mediastinum abnormalities?
Pneumomediastinum
Hydrothorax (Pleural effusion)
Accumulation of excessive fluid within the pleural space.
Best viewed in lateral decubitus view. 5ml of pleural fluid can be seen.
Diaphragm looks like a hockey stick.
Pneumothorax
Collection of air within the pleural space.
CXR appears completely black with atelectasis of lung.
PUSHES the other structures away.
Alveolar disease
Occurs when something other than air fills the alveoli. The type of fluid depends on the disease process. Infiltrates are shadows or opacities. They often have lucent tubular structures running through which represent air bronchograms. ie: pneumonia
Pulmonary edema
Typically cephalization is seen. This is increased visualization of pulmonary blood vessels in the nondependent regions of the lung. Often a sign a left heart failure.
Kerley B lines are also seen. (run perpendicular away from pleural edge.)
Interstitial lung disease
This is the part of the lung that frames the airspaces and supports the vessels and bronchi. Patient has diffuse, bilateral infiltrates. They are nodular, and HONEYCOMBING is seen.
Atelectasis
Volume loss. Plate atelectasis will show a subsegmental portion of the lung localization. Surrounding tissues collapse in to fill the space, the diaphragm becomes elevated on the side of atelectasis, mediastinum shifts toward the atelectasis, and space between ribs is narrowed.
Mediastinum compartments
Anterior
Middle
Posterior
Alveolar (Airspace) Disease
Air bronchograms Fluffy opacities Rapid coalescence Acinar nodules Segmental/lobal distribution
Interstitial Disease
Nodules Linear/ reticular opacities Septal lines Cysts Honeycombing
Signs of cardiac decompression
Cardiac enlargement
Pleural effusion
Redistribution of blood flow to the upper lobes
Poor definition to central vessels (perihilar haze)
Kerley B lines
Alveolar filling
