What’s in a name?

My lab is in the final stages of a software update that will allow for electronic signing of our reports. This has been a long and slow process partly because the release date of the software got pushed back several times but mostly because a wide variety of different hospital departments and sub-departments have had to be involved.

In all the years that I’ve had computers in the pulmonary function lab I’ve never gone through a software update that was either as easy as expected or occurred within the original schedule. This includes the time when all we had was a single IBM PC/AT with a 40 megabyte hard drive, no network and the only people that cared we were going through an update was ourselves. Since we now have a dozen networked PCs located in two different building on-campus as well as three off-site locations using an IS-managed SQL server and HL7 interface I didn’t have any expectations for a speedy update and so far I have not been disappointed.

This time because the update revolves around electronic signing the hospital’s Health Information Management (HIM, i.e. Medical Records) department has been significantly involved. Among other things this has led to HIM reviewing all of our reports and requiring changes to bring them up to hospital standards. To some extent this make sense since, for example, they require that patient identification be exactly the same on all reports from all departments (same fields, same locations).

However, they also questioned some of the terminology used on our test reports. We’ve used the default test names that were in our report format editor (yes, we’re that lazy) and until they were brought to our attention I never really thought how odd some of them were. In particular, some of the terms used for the diffusing capacity didn’t make a lot of sense. For example, DLCO corrected for hemoglobin was DsbHb and DLCO/VA was reported as D/Vasbhb. To some extent I understand where these names came from but the reality is that they are in part holdovers from the past, in part they come from a need to keep names short so they fit in what space is usually available on reports, and in some cases they were probably created by programmers who hadn’t the slightest idea what the correct nomenclature should have been.

Note: Dsb likely comes from a time when you needed to differentiate between the results of different types of DLCO tests (steady-state and single-breath). Since there hasn’t been a test system built for at least 40 years that could perform a steady-state DLCO, the need to make this distinction is long since past.

We explained what the acronyms meant, agreed that they probably needed to be updated and included a list of ATS/ERS accepted acronyms. HIM however, decided that they didn’t meet their standards and took it upon themselves to “fix” them without our help. Here is what they “fixed”:

Old: New:
Dsb DLCO/SB
DsbHb DLCOcorr
VAsb VA/SB
Vinsp VI
D/VAsbHb DL/VA/SB/Hgb

They said their decisions were based on PubMed and Fishman’s Pulmonary Diseases and Disorders, 4th Edition, 2007. Being somewhat snide I’d say it was more likely that somebody Googled it (or if I was feeling particularly snide I would have said they Binged it) and took the first listing that came up.

The fact is that over the history of pulmonary function testing many researchers and educators in different times and different places have used different terms for the same thing. The profusion of test names that occurred in the early 1950’s is in large part why the British Thoracic Society convened a special meeting in 1956 to standardize terminology. That hasn’t prevented a certain amount of originality and ingenuity (not to mention stubbornness and laziness) from creeping into our nomenclature over the years, however.

The ATS/ERS statements on standardization that were published in 2005 each include an identical list of accepted acronyms. The ones that in particular apply to DLCO are:

DL,CO Diffusing capacity
DM Membrane diffusing capacity
Hb Hemoglobin
VA Alveolar volume
VI Inspired volume
DL,CO/VA KCO

Note: Interestingly, the ATS/ERS does not have any terminology for hemoglobin-adjusted DLCO values. I suspect this is because the ATS/ERS recommends that the predicted DLCO be adjusted for hemoglobin, not the observed. No lab or manufacturer I know of follows this recommendation and it is the observed value for hemoglobin that is almost universally adjusted instead. That leaves it up to users and manufacturers to come up with acceptable terms and that means we end up with acronyms like DLCOcorr, DLCOHb and DLCOadj.

The terminology for spirometry and lung volumes is fairly standard world-wide and you won’t see any notable differences between glossaries in these areas. The notation used for gas pressures and concentrations is also reasonably well standardized although there does seem to be a lack of consensus about the use of commas and subscripts. Specifically, depending on which glossary you look at the fractional concentration of oxygen can be expressed as:

FiO2

FIO2

Fi,O2

FiO2

The least amount of consensus can be found in diffusing capacity. Depending on the glossary results can be expressed as:

DCO

DLCO

DlCO

DL,CO

DLCO

DlCO

Except for those who say that diffusing capacity should really be called transfer factor and insist that the proper terminology is actually:

TLCO

TL,CO

TLCO

There are good arguments for and against any particular style of terminology. I understand the appeal of using subscripts and commas to make precise (although occasionally somewhat esoteric) distinctions but at the same time results have to be printed on paper or viewed on a computer screen and the space required to display a term and its readability are just as important, if not more so (I’d say Down With All Subscripts! but that’s somewhat redundant, isn’t it?). Precision is important but there is also a limit as to how far we have to carry it. For example, we already accept that some values are reported as being corrected for BTPS and some for STPD and that it isn’t necessary to include this information in our terminology.

The fact is that we can read all the variations of a single acronym or term and although we sometimes have to shift mental gears we know what they mean. For this reason my suggestion would be that for any term there should be a precise “scientific” version that should be used in journal articles and textbooks (we can let the researchers and educators argue over subscripts and commas) and a simplified “readable” version meant for reports.

In the meantime though, when it comes to arguing with HIM, we’ll use the terminology lists from the ATS/ERS standardization articles. I don’t agree with all of what’s on these lists, and we’ll still have to argue about which term to use for hemoglobin-adjusted DLCO but it’s got to be better than having DL/VA/SB/Hgb on a report.

Each profession has its own language and learning the words and what they mean is a key part of understanding that field. For a variety of reasons pulmonary function terminology has a certain amount of variability that has the potential to be occasionally misleading or at least difficult to understand. I don’t think we’re quite at the point where we need to convene a special meeting of the ATS/ERS to lock down terminology, but I’d like to see all pulmonary function terminology addressed and updated in the next set of standards.

A final point is that the amount of time we need in order to prepare for a software update has gotten completely out of hand. We’ve been having meetings of one kind or another with ourselves, the manufacturer, and the different hospital departments and sub-departments just about every two weeks for the last eight months. And we’re still not ready to go live with the update.

This problem is not unique to my hospital either since I’ve heard similar complaints from other institutions around the country. I realize that the hospital environment is completely different from what it was 25 or 30 years ago when every department pretty much went its own way. I also realize that this “simple” software update impacts more departments than just ourselves. But the real reason this process has taken so long is that both hospitals and manufacturers continue to re-invent the wheel and this means that every time we want to go through an update we have to start from scratch. None of us, and that includes labs, hospitals and manufacturers, can afford the drain on resources this kind of process is taking. It is long past the time that standards (technical, procedural and legal) were developed and adhered to by everybody concerned.

References:

Brusasco V, Crapo R, Viegi G. ATS/ERS Task force: Standardisation of pulmonary function testing. Standardisation of spirometry. Eur Respir J 2005; 26: 319-338.

Brusasco V, Crapo R, Viegi G. ATS/ERS Task force: Standardisation of pulmonary function testing. Standardisation of the measurement of lung volumes. Eur Respir J 26: 511-522.

Brusasco V, Crapo R, Viegi G. ATS/ERS Task force: Standardisation of pulmonary function testing. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur Respir J 2005; 26: 720-735.

Cotes JE, Chinn DJ, Miller MR. Lung Function, Sixth Edition, Blackwell, 2006.

Ruppel GL. Manual of pulmonary function testing, Eighth edition, Mosby, 2003.

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