Anatomic dead space
I’d spent some time researching single-breath tests a while back and of course ran across the Fowler method for measuring anatomic dead space. It’s a relatively simple test but assessin…
I’d spent some time researching single-breath tests a while back and of course ran across the Fowler method for measuring…
30 Aug 2015 August 30, 2015 by Richard Johnston • Leave a comment
Proposal to improve the readability of flow-volume loops
I’ve been planning on putting together a tutorial on characterizing and interpreting the contours of flow-volume loops so I’ve been accumulating flow-volume loops that are examples of d…
I’ve been planning on putting together a tutorial on characterizing and interpreting the contours of flow-volume loops so I’ve been…
23 Aug 2015 August 23, 2015 by Richard Johnston • Leave a comment
DLNO isn’t the same as DMCO but sometimes it’s useful to pretend it (almost) is
Oxygen transport between the lungs and the body depends on numerous complex factors. Ventilation and the alveolar-capillary surface area are of course important but a critical component is hemoglob…
Oxygen transport between the lungs and the body depends on numerous complex factors. Ventilation and the alveolar-capillary surface area are…
16 Aug 2015 August 16, 2015 by Richard Johnston • Leave a comment
Alveolar O2 and Altitude
Recently I was trying to explain the effect of altitude on blood oxygenation to somebody with IPF. They had observed that their oxygen saturation was fairly normal at sea level but…
Recently I was trying to explain the effect of altitude on blood oxygenation to somebody with IPF. They had observed that…
9 Aug 2015 August 9, 2015 by Richard Johnston • Leave a comment
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…
My lab is in the final stages of a software update that will allow for electronic signing of our reports.…
2 Aug 2015 August 2, 2015 by Richard Johnston • Leave a comment
Ultrasonic spirometers
There are at least a half dozen companies that use an ultrasonic flowmeter in their spirometer. The first patent for an ultrasonic flowmeter was made in the 1970’s but it…
There are at least a half dozen companies that use an ultrasonic flowmeter in their spirometer. The first patent for…
27 Jul 2015 July 27, 2015 by Richard Johnston • Leave a comment
Temperature (in)correction
Sooner or later we all get lucky and find ourselves able to replace older equipment. When you have equipment that’s so old it can’t be repaired (either because the manufacturer…
Sooner or later we all get lucky and find ourselves able to replace older equipment. When you have equipment that’s…
19 Jul 2015 July 19, 2015 by Richard Johnston • Leave a comment
Filter FUD
A lab manager recently emailed me and asked my opinion about whether it was okay to use generic mouthpiece filters on their test systems. They had asked the same question…
A lab manager recently emailed me and asked my opinion about whether it was okay to use generic mouthpiece filters…
12 Jul 2015 July 12, 2015 by Richard Johnston • Leave a comment
Hyperventilation Syndrome
While reviewing a CPET I noticed the patient had a low PETCO2 throughout exercise and an elevated Ve-VCO2 slope. In addition the patient’s minute ventilation was on the high side…
While reviewing a CPET I noticed the patient had a low PETCO2 throughout exercise and an elevated Ve-VCO2 slope. In…
8 Jul 2015 July 8, 2015 by Richard Johnston • Leave a comment
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