Diffusing Capacity -Equipment / Report Interpretation

1
Diffusing Capacity -Equipment / Report
Interpretation

• RET 2414L
• Pulmonary Function Testing
• Module 4.0

2
Diffusing Capacity

• DLcosb

3
Diffusing Capacity

• DLcosb
• Equipment Required
• Spirometer
• Volume Displacement
• Pneumotachometer
• Test Gas
• 0.3 CO
• 10 He (tracer gas)
• 21 O2
• Balance Nitrogen

4
Diffusing Capacity

• DLcosb
• Equipment Required
• Helium Analyzer
• Thermal conductivity analyzer (wheatstone bridge)
• CO Analyzer
• Infrared absorption analyzer
• Quick response for DLco measurement
• Calibrate to room air (O) and a known
  concentration of CO
• Condensation in tubing would cause a slow
  response

5
Diffusing Capacity

• DLcosb
• Equipment Required
• 5-Way Free Breathing/Demand Valve
• Breathing Manifold
• Consists of multiple ports and valves
• Ports allow inspired or expired gas to be
  directed to the spirometer or gas-sampling
  devices
• Computer control allows different combination of
  valves and ports to be opened and closed

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Diffusing Capacity

• DLcosb
• Assignment of Severity
• Normal 80-120 of Predicted
• Mild 60-79 of Predicted
• Moderate 40-59 of Predicted
• Severe 20-39 of Predicted
• Very Severe lt20 of Predicted
• Taken from Pulmonary Function Testing and
  Cardiopulmonary Stress Testing by Vincent C.
  Madama

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Diffusing Capacity

• DLcosb
• DL/VA
• DLco is directly related to lung volume in
  healthy individuals
• DL/VA is approximately 4-5 ml CO
  transferred/minute/liter of lung volume

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Diffusing Capacity

• DLcosb
• DL/VA
• DL/VA is useful in differentiating between
  restrictive and obstructive disease
• Obstruction Low DL/VA ratio
• Restriction DL/VA Ratio is preserved

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Case Study 5 1

• History
• P.M. is a 55-year-old woman referred to the
  pulmonary function laboratory because of
  shortness of breath on exertion. She a
  38-pack-year smoking history, but stopped smoking
  6 months ago. She still coughs each morning, but
  her sputum volume has decreased since she stopped
  smoking. She has no significant environmental or
  family history of pulmonary disease. She had
  been using an inhaled ?-agonist but withheld it
  for 12 hours before the test.

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Case 5 1

• Personal Data
• Age 55
• Height 65
• Weight 137 lb
• Race African American

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Case 5 1

• Spirometry
• Pred Act Pred Post
  Pred ?
• FVC (L) 2.89 2.77 96 2.82 98 2
• FEV1 (L) 2.30 1.91 83 2.01 87 5
• FEV1 80 69 - 71 -
• FEF 25-75 2.33 1.44 62 1.51 65 5
• PEF 6.08 4.01 66 5.13 84 28

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Case 5 1

• Lung Volumes
• Pred Act Pred
• TLC (L) 4.39 4.97 113
• FRC (L) 2.45 3.10 127
• RV (L) 1.58 2.20 139
• VC (L) 2.89 2.77 96
• IC (L) 1.94 1.87 96
• ERV (L) 0.87 0.90 103
• RV/TLC 36 44 -

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Case 5 1

• Diffusing Capacity
• Pred Act Pred
• DLcosb 19.7 10.0 51
• DLco (corr) 18.1 10.0 55
• VA (L) 4.39 3.99 91
• DL/VA 4.49 2.51 46
• Hb (g/dl) 11.0