Ch. 4 Flashcards
What are the normal values for diagnosing pulmonary disease?
> 80% - <100%
All methods use what _______ .
CO
What is used to assess gas exchange and estimate lung volumes?
DLCO
What is DLCO?
Measures the diffusion of CO across the alveolar capillary membranes.
Why do we use DLCO?
Because carbon monoxide adheres to hemoglobin approximately 210 times more readily than O2.
Significant ⬇️ of CO in exhaled example w/diffused 80% or more indicates what?
Good gas exchange
If the measurements are the same or similar (diffused < 80%) what does that indicate?
Limited gas exchange
What are the 3 types of DLCO?
DLCOsb - single breath (most commonly used)
DLCOrb - restricted breath (research)
DLCOib - intrabreath (exercising)
How long do you hold DLCOsb?
10 sec
DLCOsb is good for everything except?
Exercise
DLCO will be inc. during exercise due to?
Inc. temp, ventilation, and flow.
DLCO is very sensitive to?
Distribution of ventilation and V/Q mismatch
Causes of V/Q mismatch?
Anything that hinders the body’s ability to deliver enough oxygen to your bloodstream.
• COPD exacerbation
• asthma
• pneumonia
• chronic bronchitis
• pulmonary edema
• airway obstruction
• PE
• OSA
What is HB?
Protein molecule in RBCs that carries oxygen from lungs to tissues, and returns CO2 to the body.
What are the ranges for hemoglobin?
13.5 - 17.5 (M)
12 - 15.5 (F)
How much does the machine use for males and females?
14.6% (M)
13.4% (F)
Low HB reduces ______ because there is not enough to carry and pick up ____ .
DLCO; CO
What is COHB?
Stable complex of CO that forms in RBCs when CO is inhaled
What are the percentages for COHB?
<3% for non smokers
4-10% smokers
> 50% fatal
Machine consumes 2%
When a patient smokes before the test or is a heavy smoker they will have?
An inc. COHB
The amount of time to defuse the increase in CO will take longer than the predicted______ sec.
10
If you make adjustments for elevated CO______ would be higher because it reduces the value of the predicted values.
DCO
How do you perform a DLCOsb?
- patient breathes normal VT to establish baseline
- exhale to RV
- inhales to max RV and hold for 10 seconds
- inhale special gas mixture from reservoir or spirometer.
- tracer gas 0.3%, CO, 21%, O2, N2, CH4 or Ne
- exhales to RV
- basically in SVC w/10 second breath hold
If you have a leak, your DLCO will be ______?
Increased
The ______ method measures breath hold from _____ of the Ti to the midpoint of the alveolar sample.
Jones; 0.3
All DLCO must be corrected to?
STPD (standard temp (0.C) and standard pressure (760 mmHg absolute) dry no H2O content.
Temperature, pressure, volume, and condensation, will all be?
Increased
All measurements are reported at ______?
BTPS (Body, temp, pressure, sats)
BTPS presume the combined environmental circumstances of a body temperature of______
PB of ________ mmHg breathing sats w/water vapor (=100% relative humidity).
37 degrees C; 700
For acceptable results you need…..
• average of two best tests (no more than 5)
• Tests must be acceptable & replicable
• results must be within 3mL/CO/min/mmHg
Decrease in DLCO <80% means what?
• poor gas exchange
• restrictive or obstructive
• sarcoidosis
• scleroderma
• cystic fibrosis
• emphysema
An increase in DLCO is associated with circumstances which there was an increase in _____ binding sites for _____ uptake.
HB;CO
What are diseases that will have an increase DLCO
• Polycythemia
• Alveolar hemorrhage
DLCO will always be increased during?
Exercise testing
What do we do for an obstruction?
We look at DLCO to determine severity of gas exchange and emphysema
Which obstructive disease is low?
Emphysema
CBABE
All other obstructive diseases are normal
What do we do for a restriction?
Look at DLCO to see if restriction is interstitial or extrastitial
DLCO < 80% means?
Restriction is happening inside lungs
A normal DLCO means what?
Restriction is happening outside the lungs
In mix defect defining ______ in the DLCO can be very _____.
Decrease;difficult
We won’t know if the disease is ______ or ______.
Restrictive or obstructive
Mixed defect relies on the patients…..?
• history
• work environment
• medical data (x-rays, lab, previous diagnosis)
What is mixed defect used for?
To come up with a hypothesis or a possible diagnosis
