PHGY 210 Lecture 8: PHGY 210- Lecture 8- Dr. Lauzon.docx.docx
14 May 2012
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Lecture eight- wednesday, january 20th, 2010: spirometry: measuring lung volumes. All the air in the lungs=total lung capacity. Spirometer can measure only what you can breathe in and out. However, total lung capacity cannot be measured because you"re not breathing out residual volume. Clinically, it is useful to be able to measure the volume of air inhaled during inspiration under a number of different circumstances. It cannot be used to measure functional residual capacity, total lung capacity, or residual volume. see pictures in slides: measurement of frc. Helium dilution technique: subject hooked up to a spirometer, helium is in the tube (dissolved in air). Subject breathes out to frc, that"s when valve is opened up and subject breathes helium. Can use mass spectrometer to measure new [helium] which is lower, because it is now over a larger volume (c2). Frc can be measured by helium dilution (figure 10).
