The chemo did a real number on me. I was included in a study of a new drug and it literally almost killed me. Twice. For this reason I have left the study and have been put on a gentler and more normal regime of chemo. I have lost a lot of stamina (and strength and weight) but have recovered somewhat. I have returned to catch up on comments as best I can and apologize for not responding for so long.

If possible I will post something new but it will probably be a while before I feel up to doing so.

Thanks to everybody for their kind and supportive thoughts.

This is probably the last post I will be able to write.  I was diagnosed less than two months ago with a very nasty cancer with a poor prognosis.  I thought I could power through it but a serious infection with sepsis and a week and a half stay in the hospital has convinced me that it’s time to quit and focus on other things.

Sucks, but that’s life.

There are many pulmonary function topics I would have liked to discuss but time has run out.  I will leave you to ponder the two biggest elephants in the room; that of height and that of ethnicity.  The relationship between height and FVC, TLC, etc. is inexact and yet nobody seems to think about any alternate anthropomorphic measurements.  Sitting height is only marginally better but it is better.  Is anybody using it?  No.  C’mon people, it’s way past time that we found better anthropomorphic correlations for FVC, FEV1, TLC and DLCO.

And what the heck is ethnicity?  Where is there a definition for it?  Although I applaud the GLI efforts for more universal FVC reference values they included fudge factors for ethnicity.  Fudge factors!!??.  It’s time that the concept of ethnicity was dropped and better (see above) anthropomorphic correlations were made.

Keep learning.  Keep questioning.

Goodbye.

– UPDATE – 

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A couple of days ago I was reviewing (triaging, actually) the spirometry portion of a full panel of PFTs performed with pretty terrible test quality and was trying to decide if the technician responsible for performing the tests had made the right selections from the patient’s test results. I noticed that the FEV1 that had been selected was actually the lowest FEV1 from the all the spirometry efforts the patient made, and was trying to decide whether this was really the correct choice. We use peak flow to help determine which FEV1 to select and that particular spirometry effort appeared to have the highest and sharpest peak flow by a large margin:

particularly when compared to the other spirometry efforts:

But this was hard to reconcile given how low the FEV1 was relative to the others:

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I was contacted recently by an individual with some questions about the pulmonary function testing needed for a Social Security Disability evaluation. With a small amount of research I was able to answer their questions but this brought up an interesting point and that is that despite the number of patients we see every year my lab only rarely performs any pulmonary function testing for disability evaluations. The reason I know this is because the Social Security Administration (SSA) has very specific requirements for the content and form of pulmonary function reports and we are very rarely asked for these reports.

The pulmonary function tests the SSA uses as part of a disability evaluation are:

• Spirometry
• Diffusing Capacity (DLCO)
• ABG
• Pulse Oximetry

Interestingly, lung volume measurements are not included. This is not specifically explained but it appears to be because evaluation for restriction is covered by the criteria for FVC and FEV1.

For all pulmonary function tests the SSA requires that the individual be medically stable, which they define as not:

• Within 2 weeks of a change in prescribed respiratory medication.
• Experiencing, or within 30 days of completion of treatment for, a lower respiratory tract infection.
• Experiencing, or within 30 days of completion of treatment for, an acute exacerbation of a chronic respiratory disorder.
• Hospitalized, or within 30 days of a hospital discharge, for an acute myocardial infarction (heart attack).

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Most of the COPD patients that are seen in my lab tend to have little change in their FEV1 from visit to visit but their FVC often changes significantly. A change in FVC is usually related to how long a patient is able to exhale and this in turn is usually related to how well they are feeling at the time. This would seem to imply that a significant change in FVC, particularly for a patient with COPD, is, if not clinically significant, at least clinically important even when the FEV1 hasn’t changed.

The problem with this is that expiratory time can be affected by things other than how the patient is feeling. Dyspnea and fatigue, of course. As importantly some technicians are better at motivating patients than other technicians so it can also be related to which technician is performing their tests. Even when the same technician is involved however, there is no guarantee that the level of motivation or a patient’s response to that motivation will be the same.

So how do you know if a change in FVC clinically significant or not?

Recently a spirometry report from a patient with very severe COPD came across my desk. When comparing the results to those of the last visit I could see that there had been a small (but not significant) increase in FEV1 but at the same time there had been a large (and significant) increase in FVC.

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