Biomed 100 - Pulmonary Volumes
Reference: Hole's Essentials of Human Anatomy and Physiology, 9th. ed., pp. 440-441



Spirometry refers to the measurement of lung volumes and capacities. An instrument called a spirometer measures respiratory air volumes except residual volume, which requires a special technique. Such measurements are used to evaluate the courses of emphysema, pneumonia, and lung cancer, conditions in which functional lung tissue is lost. These measurements may also track the progress of diseases such as bronchial asthma that obstruct air passages.
About the Air Flow Transducer (AFT)
  1. Handle the air flow transducer (AFT) very carefully.
  2. Plug the AFT into Channel 1 of the BioPac unit.
  3. Plug all inserts into the port that faces you while the wire is on your left.
  4. Hold the AFT by its clear plastic top piece when pushing on or pulling off any inserts.
  5. When using the syringe, hold the barrel of the syringe in one hand and hold the handle of the plunger with your other hand.
Obtaining "Uncorrected Data"
  • use BioPac Lesson L12-Lung-1
  • you may find it useful to make this window short and wide and place it near the bottom of your screen
  • once you have entered "Record" mode, do not press any computer buttons, including on-screen buttons, until specifically told to do so
  1. While holding the clear plastic top piece of the AFT, insert the calibration syringe. The handle should be pushed in completely.
  2. Click Calibrate, click OK, and wait 8 seconds.
  3. Click Yes but do not follow the on-screen instructions.
  4. After a few seconds, click End Calibration.
  5. Click Record.
  6. Holding the barrel of the syringe, not the AFT, pump the syringe three times at your approximate respiratory rate.
  7. Without clicking any buttons, hold the AFT by its clear plastic top piece, remove the syringe, install a filter and a mouthpiece.
  8. Stand and seal your nose with one hand. While between breaths (neither inhaling nor exhaling), put the mouthpiece into your mouth, and generate a spirogram like the one on the board. (The real-time recording will not resemble the desired spirogram.)
    • Breathe normally for at least three tidal cycles.
    • For VC, inhale fully then exhale fully. This can be done slowly.
    • Return to normal breathing for a few more cycles.
    • For FEV and FVC, inhale fully, then exhale as rapidly and completely as possible.
  9. Click Stop. While holding the AFT by its clear plastic top piece, remove the filter and mouthpiece.
  10. To measure volumes (liters), refer to the "Volume" graph and use p-p from a pull-down menu.
  11. On the Uncorrected Data section of your individual Response Sheet, record the volumes for at least one cycle of pumping the syringe, your VC, FEV, and FVC.
    • To measure the syringe volume, drag the I beam from the high point to the low point of a typical pump cycle.
    • To measure the vital capacity (VC), drag the I beam from the highest point after maximal inspiration to the lowest point after maximal expiration.
    • To measure the forced expiratory volume in one second, or "FEV(1)":
      • Select delta-T from one of the pull-down menus.
      • Use the magnifier to enlarge the recording of the forced expiration.
      • Put the I beam at the beginning of the FEV (where it begins to drop steeply), hold down the mouse button and drag to the right until delta-T reads "1 second." The (uncorrected) FEV is the volume in the p-p window.
    • To measure the forced vital capacity (FVC), return the I beam to the beginning of the FEV (where it begins to drop steeply). Now drag to the right until the lowest point has been reached. The (uncorrected) FVC is the volume in the p-p window.
  12. Get the uncorrected values for all students in your group before going to the next section. To repeat the recording process for the same subject or another subject, the system must be re-calibrated. Click Redo and return to Step 5.
Obtaining "Predicted Values"
  1. You will need to find your predicted VC (VC that is considered normal) for a person of your age, height, and sex. Use the appropriate printed table and record on the Predicted VC line.
  2. Use the following menu to find your predicted FEV1 and FVC (values that are considered normal for a person of your age, height, and sex).
Obtaining "Corrected and Calculated Values"
  1. Enter your Uncorrected and Predicted values on the BMS100 Pulmonary Volumes Spreadsheet.
  2. Transfer the corrected and calculated values to your individual Response Form.