DLCO Flashcards
What is a normal value for DLCO?
25 mLCO/min/mmHg STPD
How do increases/decreases in Hb and Hct affect DLCO?
An increase or decrease in either will similarly increase/decrease DLCO because there are more/less sites to bind the CO. More Hb = more binding sites. Less Hb = less binding sites.
How does PACO2 affect DLCO?
An increase in PACO2 will decrease DLCO because there is a fixed volume of gases in the lungs. If more of the space is used by the increased PACO2, there is less space for O2 or CO
How does increased COHb affect DLCO?
Increased COHb will decrease DLCO due to backpressure. Less of the CO will diffuse into the body because of the existing CO in the Hb.
How could you position a patient that is sitting up to increase DLCO?
Have the patient lie down. Lying down will increase DLCO because of the increased pulmonary blood flow vs sitting up.
How long should a patient refrain from smoking before a DLCO test? Should they do any heavy exertion?
The patient should try to avoid smoking for 48 hours. Heavy exertion is not recommended.
Note: for a DLCO SB, the patient should not smoke for 24 hours.
Will DLCO increase or decrease in patients with restrictive diseases?
It will decrease. Smaller lung volumes and increased membrane thickness in the lungs will make it harder for CO to diffuse into the body.
What is the only obstructive disease that will decrease DLCO?
Emphysema. This is due to the decrease in surface area caused by emphysema.
Note: if you have to pick between 2 obstructive diseases on the exam and DLCO is decreased, what should you pick?
Emphysema. It is the only obstructive disease that will decrease DLCO.
Acceptable DLCO results should be within ___% of each other.
10% or 3ml CO/min/mmHg
What should you report after a DLCO test?
The mean of at least 2 acceptable maneuvers that are within 10% of each other.
