Vd/Vt, how accurate is it really?
My lab stopped inserting A-lines to get arterial blood samples during exercise testing well over 10 years ago. Our decision was partly based on the fact that we didn’t do them often enough to…
Month April 2014
It wasn’t a leak
The most common problem we have with helium dilution FRC tests are leaks. Although the system tubing and spirometer bell leak occasionally, we do have valve failures relatively frequently. Valve fa…
Pneumotach accuracy
The first reasonably accurate flow-measuring device was the Fleisch pneumotachograph which was developed in 1925. Originally the Fleisch pneumotach bounced a light beam off a mirror mounted on a di…
Student spirometers, what can they teach?
It’s been several decades since I last saw water-seal bell spirometers being used in a Pulmonary Function lab. They have been displaced mostly by systems that use flow sensors of one type of …