DLCO and the Single Breath Test

One Pulmonary Function Test (PFT) follows the forward march of my Interstitial Lung Disease. It is called the Single Breath Test.

Here is the definition from a medical dictionary:

nitrogen washout test, single breath  the patient inhales a vital capacity's volume of pure oxygen and then slowly exhales. The nitrogen content of the exhalation is measured over the entire breath and a curve is generated; different parts of the curve represent nitrogen concentrations of gas in different components of the total lung capacity, and can be analyzed for irregularities. Called also single breath test.

Sounds simple, doesn’t it? It starts with taking in a huge breath then exhaling slowly until there is no air left in the lungs.

Here are my Single Breath Test numbers:

1. 6/05 – 41%
2. 10/05 – 54%
3. 6/06 – 51%
4. 9/07 – 51%
5. 1/08 – 49%

A steady march downward. The difference between June and October of 05 is due to Prednisone. It really made a difference.

Here are my Lung Capacity (VC) numbers for the same time period:

1. N/A
2. 63%
3. 67%
4. 57%
5. 61%

Here are the all-important DLCO numbers also for the same time period:

1. 10.8 or 41%
2. 12 or 45%
3. 12.8 or 49%
4. 11.6 or 44%
5. 13.4 or 51%

I still shiver when I see the DLCO numbers. My first PFT in November of 2004 was 7.7. They transplant at 7. Again, any number under 35 is considered severe. I can understand how the doctors are amazed that I am able to function so well. Sheer will, I guess.