Author Question: Which of the following are necessary to ensure a valid single-breath diffusing capacity of the lungs ... (Read 74 times)

bobthebuilder · **on:** Jul 16, 2018

Which of the following are necessary to ensure a valid single-breath diffusing capacity of the lungs (DLCO) test result?

1. Two or more acceptable tests should be averaged.
2. Breath-hold time should be between 3 and 5 sec.
3. Corrections for hemoglobin (Hb) and COHb should be included.
4. The maneuvers should be reproducible to within 10.
a. 1, 2, and 3 only
b. 2 and 4 only
c. 1, 3, and 4 only
d. 1, 2, 3, and 4

Question 2

A patient has a decreased DLCO but a normal DLCO/VA ratio. The patient most likely has:

a. emphysema.
b. pulmonary fibrosis.
c. a small lung (low total lung capacity).
d. secondary polycythemia.

dudman123 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
The mean of two acceptable tests is the DLCO that meet the repeatability requirement of either being within 3 ml of CO (STPD)/min/mm Hg of each other or within 10 of the highest value.

Answer to Question 2

ANS: C
The diffusing capacity of the lung to effective total lung capacity ratio (DLCO/VA) differentiates between diffusion abnormalities caused by having a small lung volume compared with diffusion abnormalities caused by alveolar-capillary membrane pathologies. Patients whose only problem is small lungs will have a decreased DLCO, but their DLCO/VA ratio will be normal. Patients with pulmonary emphysema or fibrosis will have a decreased DLCO and a decreased DLCO/VA ratio.