Lung Volumes and Gas Distribution Tests
Case 1:
HISTORY
The patient is a 77-year-old white woman with a long history of COPD. She was referred by her internist because of increasing shortness of breath on exertion. She has a nonproductive cough, usually at night. She denies any wheezing or orthopnea but complains of worsening shortness of breath. She had been attending a pulmonary rehabilitation program but was forced to stop because of the dyspnea. She has a smoking history of 180 pack-years and a family history of asthma and hay fever. She was taking ipratropium (Atrovent) and salmeterol (Serevent) at the time of testing.
PULMONARY FUNCTION TESTING
| Personal data | |
| Name: | C.R. |
| Age: | 77 |
| Height: | 62 in |
| Weight: | 170 lb |
| Race: | White |
| Prebronchodilator | Postbronchodilator | |||||
| Pred | Actual | %Pred | Actual | %Pred | %Change | |
| Spirometry | ||||||
| FVC (L) | 2.43 | 2.22 | 91 | 2.12 | 87 | –5 |
| FEV1 (L) | 1.66 | 0.93 | 56 | 0.95 | 57 | 3 |
| FEV1/FVC (%) | 68 | 42 | 45 | 8 | ||
| FEF25%-75% (L/sec) | 2.91 | 0.32 | 11 | 0.33 | 11 | 3 |
| FEFmax (L/sec) | 5.42 | 2.13 | 39 | 1.96 | 36 | -8 |
| MVV (L/min) | 75 | 34 | 46 | |||
| Lung Volumes | ||||||
| SVC (L) | 2.43 | 2.06 | 85 | |||
| TLCpl (L) | 4.25 | 5.61 | 132 | |||
| RVpl (L) | 1.82 | 3.55 | 196 | |||
| FRCpleth (L) | 2.53 | 4.02 | 159 | |||
| RV/TLC (%) | 43 | 63 | ||||
| Diffusion | ||||||
| Dlcounc (ml/min/mm Hg) | 16.3 | 4.7 | 28 | |||
| Dlcocor (ml/min/mm Hg) | 16.3 | 7.7 | 47 | |||
| DL/VA | 3.84 | 2.35 | ||||
| VA (L) | 4.25 | 3.28 | ||||
| Airway Resistance | ||||||
| Raw (cm H2O/L/sec) | 0.5-2.5 | 2.19 | ||||
| sGaw (1/cm H2O•scx) | >0.20 | 0.10 | ||||
| Blood Gases | ||||||
| pH | 7.40 | 7.44 | ||||
| Paco2 (mm Hg) | 35-45 | 41 | ||||
| Pao2 (mm Hg) | 76 | 89 | ||||
| HCO3– (mEq/L) | 27.2 | |||||
| Hb (g/dl) | 5.2 | |||||
| Sao2 (%) | 94.1 | |||||
| COHb (%) | 0.4 | |||||
TECHNOLOGIST’S COMMENTS
Spirometry: there was no obvious plateau after 10 to 12 seconds, otherwise acceptable. Lung volumes by plethysmography were acceptable. Raw was acceptable with marked expiratory resistance. Dlco breath hold times were less than 11 seconds, otherwise acceptable. Corrected for Hb of 5.2.
QUESTIONS
- Interpret the following:
- Spirometry before and after bronchodilators
- Lung volumes
- Dlco
- Airway resistance before and after bronchodilators
- Blood gases
- What is the cause of the patient’s symptoms?
- What other tests might be indicated?
- On the basis of these findings, what treatment might be recommended?