Category pftblog

I was contacted recently by a reader who is trying to resurrect an older test system.  It is a Spirotech S600, manufactured by Graseby-Andersen and outfitted for spirometry, helium dilution lung vo…

There are a couple of different ways to assess changes in FEV1 from one patient visit to another. For several decades my lab has used a change of >=10% and >=200 ml as the threshold for a sig…

I’ve had a number of reports across my desk in the last couple of weeks with both elevated and reduced FRC’s that were associated with a more-or-less normal TLC. I reviewed the raw data…

Roughton and Forester’s seminal paper from the 1950’s showed that DLCO was a function of two resistances: the alveolar-capillary membrane and the rate of CO uptake by red blood cells. T…

A spirometry report that looked very questionable came across my desk recently. The flow-volume loop was misshapen and the technician’s notes indicated that the results had been highly variab…

Recently I was reviewing a spirometry report and noticed that the FVC was below normal. A low FVC can suggest a restrictive lung disease but the reported expiratory time was only about 4 seconds. I…

Although the numerical results are of course important, visual inspection of the volume-time and flow-volume loop graphs from a spirometry test are a critical part of interpretation. Spirometry qua…

The single-breath DLCO maneuver can rightly be criticized as being an artificial maneuver that bears little resemblance to normal breathing. It is only by standardizing the maneuver that clinically…

Because our lab database goes back 24 years, we’ve started to see a certain number of patients who had last been seen ten or even twenty years ago fairly often. For this reason I’ve bee…

There are a number of simple observations that can be made during a cardio-pulmonary exercise test (CPET) that can point you immediately in a specific diagnostic direction. Recently I was reminded …