Which of the following are necessary to ensure a valid ...

[bobthebuilder]

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]

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.

[bobthebuilder]

Excellent

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