SPIROMETRY
Fall  2000
90 Points

     The assessment of pulmonary function is important in the diagnosis and evaluation of obstructive and restrictive pulmonary diseases.    Obstructive lung disease is clinically identified by a decrease in expiratory flow rates, the anatomical basis of which is airway narrowing.   Whereas, restrictive lung disease is clinically identified by decreased lung volumes.   Pulmonary functions utilized in the diagnosis and prognosis of these diseases include:

  • Static Lung Volumes (VC)
  • Flow Rate (FEV1)
  • Flow-Volume Loops
  • Maximal Ventilatory Volume (MVV)

    Pulmonary functions are not the only means of evaluating lung disease.  Other assessments include:

  • Diffusion Capacity
  • Arterial Blood Gases
  • Right to Left Shunts

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Turn this data form in to Dr. Wallace as soon as you collect the data.
LABORATORY PROCEDURES

  1. Have the subject perform the force vital capacity and MVV maneuvers under the following conditions:
    • Normal standing
    • Normal sitting
    • Sitting with an obstructed mouthpiece
    • Sitting with straps tightly bound around chest and abdomen

    Perform at least three trials each. Keep the best performance.

    Pulmonary Function Lab Skills:
    Forced Vital Capacity:

        Vital capacity maneuver measures dynamic and static lung volumes. Static lung volumes are single volumes whereas dynamic volumes or capacities are combinations of static lung volumes.

        The graph to the left illustrates the vital capacity maneuver.  It starts with normal tidal breathing.  Then you see the complete inhalation followed by the complete and rapid exhalation.  Then normal tidal breathing continues.
    Procedure:
    1. Make sure the subject is not chewing gum or has
      anything in their mouth.
    2. Have the subject sit and breathe normally through
      the mouthpiece.
    3. Make sure the nose clips are on.
    4. Make sure the bell is no more than half filled.
    5. Instruct the subject to fill their lung as much as
      possible.
    6. As soon as they have their lungs fully inflated,
      instruct them to blow all the air out as fast as they can.
    7. Encourage them to get all the air out.
    8. Let them breathe normally.
    9. Remove the mouthpiece.
    10. Take the nose clips off.
    11. Repeat the procedure at least three times.
    Dynamic Volumes or Capacities
    • Inspiratory Capacity
    • Vital Capacity
    • Functional Reserve Capacity
    • Total Lung capacity
    Static Volumes
    • Inspiratory Reserve Volume
    • Expiratory Reserve Volume
    • Tidal Volume
    • Residual volume is a static lung volume, but cannot be measured by the Vital Capacity Maneuver
    Flow-Volume Loops:

        The procedure for the flow volume loop is the same as for the vital capacity maneuver except that a complete inhalation is done before and after the complete exhalation.  A normal flow-volume loop is illustrated in the figure to the right.   In the flow volume loop, the flow rate (y axis) is plotted against the actual lung volume (x axis) instead of against time as in the vital capacity maneuver.   Exhalation is plotted above the x axis. Even though inhalation is plotted below the x axis, flow rates are not negative.   The plot begins at total lung capacity; with the lungs filled as much as possible.  Thus, the top half of the graph is the complete exhalation and the bottom half is complete inhalation.   Flow rates are the focus of flow volume loops.
         Flow rates are broken down into fractions of the whole maneuver. That is,
    • 25%
    • 25-50%
    • 25-75%
    Maximal Ventilatory Volume (MVV):

        MVV measures the capacity to move air in and out of the lungs.   MVV is illustrated in the figure to the left.   MVV measures the largest amount that can be moved in 10 or 20 seconds and corrects that volume to one minute. The MVV has been called the huff and puff test.   It is a series of rapid deep breaths for 10 to 20 seconds.

      

      MVV provides information for maxmial ventilation during exercise (VEmax).   In most cases, MVV does not limit maximal ventilation in exercise.

    The procedure is:

  2. Make sure the subject is not chewing gum or has anything in their mouth.
  3. Have the subject sit and breathe normally through the mouthpiece.
  4. Make sure the nose clips are on.
  5. Make sure the bell is no more than half filled.
  6. Instruct the subject to take a series of deep in and out for 10 or 20 seconds.
  7. As an example, lead them through the first few series of breaths.
  8. Encourage them to keep pushing air in and out.
  9. Stop them when time is up.
    • If they feel light headed, assure them that it is perfectly normal.
    • Tell them to breathe out and hold it for about 3 to 5 seconds.
    • Let them breathe normally.
    • If they continue to feel light headed, repeat the breath holding maneuver.
  10. Remove the mouthpiece.
  11. Take the nose clips off.
  12. Repeat the procedure at least three times.
  13. Correct the highest volume from 10 or 20 seconds to one minute.
    14. Some examples of the procedures:
    Standing Vital Capacity
    Maneuver    		 Sitting Vital Capacity Maneuver Sitting MVV Maneuver
    Using the obstructed airway Using straps to bind the chest

    1. Print out the expanded text report and separate graphs (Flow-volume Loops and MVV) for each condition.

    REFERENCES:

    1. ACSM Reference Manual
    2. Tisi, G.M., Pulmonary Physiology in Clinical Medicine, Williams & Wilkins, 1980.

    QUESTIONS

    Indicate references, including page numbers.

    1. Plot (in a histogram) the Forced Vital Capacity for each of the four conditions. (5 points)

    2. Plot (in a histogram) the FEV1 for each of the four conditions. (5 points)

    3. Plot (in a histogram) the MVV for each of the four conditions. (5 points)

    4. What is the effect of posture on pulmonary functions? (5 points)

    5. What portion of the Forced Vital Capacity maneuver demonstrates the highest and lowest flow rates? (5 pts)

    6. What does the flow-volume loop measure? (5 points)

    7. What does the MVV measure? (5 pts)

      1. What is the relationship between MVV and FEV1? (3 pts)

      2. What is the relationship between MVV and Vemax? (3 pts)

    8. What is the advantage of measuring a FVC, Flow-Volume Loop, or MVV?   That is, does each of these tests provide information the others do not?   Or do all three tests combined, provide a more well rounded picture of pulmonary functions? (5 points)

    9. List and explain the pathophysiology of three examples of Chronic Obstructive Pulmonary Diseases (15 pts).

      1. Which of the Forced Vital Capacity Maneuvers you did in lab most closely represents the PFTs and Flow Volume Loops more often found in COPD? (3 pts)

      2. What are the three common disease characteristics of COPD? (3 pts)

    10. Describe one example of Restrictive Lung Disease? (5 pts).

      1. Which of the Forced Vital Capacity Maneuvers you did in lab most closely represents the PFTs and Flow Volume Loops more often found in Restrictive Lung Disease? (3 pts)

      2. What are the common characteristics of Restrictive Lung Disease? (3 pts)

    11. What is a DLCO test measure? (3 points)
      1. Why would it be used in pulmonary disease? (4 points)
      2. List five diseases you would expect to see a reduced diffusion capacity. (5 points)