What’s abnormal about FRC?
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…
I’ve had a number of reports across my desk in the last couple of weeks with both elevated and reduced…
9 Aug 2014 August 9, 2014 by Richard Johnston • Leave a comment
DMCO, Vc and 1/theta
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.…
Roughton and Forester’s seminal paper from the 1950’s showed that DLCO was a function of two resistances: the alveolar-capillary membrane…
31 Jul 2014 July 31, 2014 by Richard Johnston • Leave a comment
When back-extrapolation goes astray
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…
A spirometry report that looked very questionable came across my desk recently. The flow-volume loop was misshapen and the technician’s…
13 Jul 2014 July 13, 2014 by Richard Johnston • Leave a comment
Mixing doesn’t always make a match
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…
Recently I was reviewing a spirometry report and noticed that the FVC was below normal. A low FVC can suggest…
1 Jul 2014 July 1, 2014 by Richard Johnston • Leave a comment
Seeing shouldn’t always be believing
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…
Although the numerical results are of course important, visual inspection of the volume-time and flow-volume loop graphs from a spirometry…
26 Jun 2014 June 26, 2014 by Richard Johnston • Leave a comment
Single-breath DLCO Breath-holding time (BHT)
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…
The single-breath DLCO maneuver can rightly be criticized as being an artificial maneuver that bears little resemblance to normal breathing.…
23 Jun 2014 June 23, 2014 by Richard Johnston • Leave a comment
Assessing change over a long period of time
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.…
Because our lab database goes back 24 years, we’ve started to see a certain number of patients who had last…
15 Jun 2014 June 15, 2014 by Richard Johnston • Leave a comment
DLO2/Qc, SaO2 and CPETs
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…
There are a number of simple observations that can be made during a cardio-pulmonary exercise test (CPET) that can point…
3 Jun 2014 June 3, 2014 by Richard Johnston • Leave a comment
Gas solubility and why it matters
I have been searching through Pulmonary Function videos on YouTube in order to find ones I thought would be useful for technician education. So far what I’ve found have been…
I have been searching through Pulmonary Function videos on YouTube in order to find ones I thought would be useful…
26 May 2014 May 26, 2014 by Richard Johnston • Leave a comment
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