GENERAL MEDICINE CONFERENCEGENERAL MEDICINE CONFERENCE

Interpreting pulmonary function Interpreting pulmonary function teststests

Selim Krim, MDSelim Krim, MDAssistant ProfessorAssistant Professor

Texas Tech University Health Sciences CenterTexas Tech University Health Sciences Center

ObjectivesObjectives Be familiar with the indications for pulmonary function tests (PFT’s)Be familiar with the indications for pulmonary function tests (PFT’s)

Use a stepwise approach when interpreting PFT’sUse a stepwise approach when interpreting PFT’s

Know how to differentiate obstructive from restrictive patternKnow how to differentiate obstructive from restrictive pattern

Be familiar with common etiologies of obstructive and restrictive Be familiar with common etiologies of obstructive and restrictive diseasesdiseases

Know how to distinguish a mixed pattern from air trappingKnow how to distinguish a mixed pattern from air trapping

Know how to distinguish parenchymal from extra parenchymal Know how to distinguish parenchymal from extra parenchymal causes of restrictive diseases causes of restrictive diseases

Indications for PFT’sIndications for PFT’s To evaluate symptoms and signs of lung disease (eg, cough, dyspnea,

cyanosis, wheezing, hyperinflation, hypoxemia, hypercapnia)

To assess the progression of lung disease

To monitor the effectiveness of therapy

To evaluate preoperative patients in selected situations

To screen people at risk of pulmonary disease such as smokers or people with occupational exposure to toxic substances in occupational surveys.

To monitor for the potentially toxic effects of certain drugs or chemicals (eg, amiodarone, beryllium)

Lung volumes and capacitiesLung volumes and capacities

Flow-volume and flow-time loopsFlow-volume and flow-time loops

Obstructive diseaseObstructive disease

Decreased FEV1/FVC ratioDecreased FEV1/FVC ratio (usually<70%) (usually<70%) AsthmaAsthma COPD ( Chronic bronchitis, emphysema)COPD ( Chronic bronchitis, emphysema) Response to bronchodilator therapy is defined by an increase Response to bronchodilator therapy is defined by an increase

of of >12% in FEV1>12% in FEV1

Staging of obstructionStaging of obstruction

I: MildI: Mild FEV1FEV1≥ 80% predicted≥ 80% predicted

II: ModerateII: Moderate 50%50%≤≤FEV1<80% FEV1<80% predictedpredicted

III: SevereIII: Severe 30%30%≤≤FEV1<50% FEV1<50% predictedpredicted

IV: Very severeIV: Very severe FEV1 <30% predicted or FEV1 <30% predicted or FEV1 <50% predicted plus FEV1 <50% predicted plus chronic respiratory failure chronic respiratory failure

Restrictive diseaseRestrictive disease

FEV1/FVC normalFEV1/FVC normal, FEV1 is decreased or normal, , FEV1 is decreased or normal, FVC is decreasedFVC is decreased, , TLC decreasedTLC decreased

Intrinsic lung diseases, which cause inflammation or scarring of the Intrinsic lung diseases, which cause inflammation or scarring of the lung tissue (interstitial lung disease) or fill the airspaces with lung tissue (interstitial lung disease) or fill the airspaces with exudates or debris (acute pneumonitis). exudates or debris (acute pneumonitis).

Extrinsic disorders, such as disorders of the chest wall or the pleura, Extrinsic disorders, such as disorders of the chest wall or the pleura, which mechanically compress the lungs or limit their expansion. which mechanically compress the lungs or limit their expansion.

Neuromuscular disorders, which decrease the ability of the Neuromuscular disorders, which decrease the ability of the respiratory muscles to inflate and deflate the lungs. respiratory muscles to inflate and deflate the lungs.

Parenchymal vs. extra Parenchymal vs. extra parenchymal causes of parenchymal causes of

restrictionrestriction

ParenchymParenchymalal

ExtraparenchymExtraparenchymalal

TLCTLC DecreasedDecreased DecreasedDecreased

DLCODLCO

(correcte(corrected)d)

DecreasedDecreased NormalNormal

Mixed pattern vs. air trapping

Mixed Mixed patternpattern

Air trappingAir trapping

FVC FVC LowLow LowLow

TLCTLC LowLow Normal or Normal or increasedincreased

Pseudorestriction or air Pseudorestriction or air trappingtrapping

Obstructive vs. Obstructive vs. restrictiverestrictive

Stepwise Approach to PFT’sStepwise Approach to PFT’s

Case 1Case 1 A 51-year-old woman presents for evaluation of shortness of breath,

cough, and wheezing especially in the summer. Her symptoms are relieved with albuterol, salmeterol, and fluticasone inhalers. She does not smoke. Her PFT’s are as follow; FVC=83%, FEV1=63%, FEV1/FVC=58.2%. After bronchodilator therapy her FVC increases by 12%, FEV1 by 34%, and FEV1/FVC ratio by 29%. Which of the following patterns is present?

A- Obstructive pattern without response to bronchodilators B- Restrictive pattern C- Obstructive pattern with response to bronchodilators

What is the severity of this patient’s defect? 1- Mild 2- Moderate 3- Severe

Case 2Case 2 A 68-year-old woman presents for evaluation of shortness of breath

without cough or wheezing. She has systemic lupus erythematosus (for which she takes prednisone and methotrexate) and hypertension (for which she takes metoprolol and hydrochlorothiazide). Her oxygen saturation is 94% by pulse oximetry while breathing room air. Her hemoglobin concentration is 12.3 g/dL. FVC=60%, FEV1=70%, FEV1/FVC=88.6%, RV=38%, TLC=53%, DLCO=38%. Which of the following best describes the pattern seen on this patient’s pulmonary function tests?

A- Obstructive pattern with suspicion of emphysema B- Restrictive pattern C- Obstructive pattern without emphysema D- Normal spirometry

Case 3Case 3 A 68-year-old woman presents for evaluation of progressive

shortness of breath. She describes 18 months of gradually increasing dyspnea on exertion. She has not noted any prominent cough, wheezing, chest pain, lightheadedness, or edema. Her review of systems is positive only for cold fingers and mild joint pains. She has never smoked and has no other medical history. Her only medication is hormone replacement therapy. Her FVC=96%, FEV1=101%, FEV1/FVC=81.7%, TLC=83%, DLCO=43%, Adjusted DLCO=59%. Which of the following are potential causes of this pattern?

A- Anemia

B- Pulmonary arterial hypertension

C- Chronic thromboembolic disease

D- Obesity

E- All of the above

Case 4Case 4 A 45-year-old man is evaluated for mild dyspnea on exertion. He has A 45-year-old man is evaluated for mild dyspnea on exertion. He has

smoked 1.5 packs of cigarettes a day for 30 years. His personal and smoked 1.5 packs of cigarettes a day for 30 years. His personal and family medical history is unremarkable. On physical examination, the family medical history is unremarkable. On physical examination, the chest is clear; cardiac examination and chest radiograph are normal. chest is clear; cardiac examination and chest radiograph are normal. Spirometry shows the FEV1 of 70%, FVC of 75%, FEV1/FVC of Spirometry shows the FEV1 of 70%, FVC of 75%, FEV1/FVC of 68%. After administration of a bronchodilator, the FEV1 rises to 80% 68%. After administration of a bronchodilator, the FEV1 rises to 80% and the FVC to 85%; the FEV1/FVC ratio is 75%. The serum IgE and the FVC to 85%; the FEV1/FVC ratio is 75%. The serum IgE concentration is normal, and there are no eosinophils on the concentration is normal, and there are no eosinophils on the peripheral blood smear. Which of the following is the most likely peripheral blood smear. Which of the following is the most likely diagnosis?diagnosis?

A- Chronic obstructive pulmonary disease, stage 0 A- Chronic obstructive pulmonary disease, stage 0 B- Chronic obstructive pulmonary disease, stage 1 B- Chronic obstructive pulmonary disease, stage 1 C- Chronic obstructive pulmonary disease, stage 2C- Chronic obstructive pulmonary disease, stage 2 D- Moderate persistent asthma D- Moderate persistent asthma E- Restrictive lung diseaseE- Restrictive lung disease

Case 5Case 5 A 64-year-old woman is evaluated for a 9-month history of progressive A 64-year-old woman is evaluated for a 9-month history of progressive

exertional dyspnea and nonproductive cough. She is an ex-smoker with a 30-exertional dyspnea and nonproductive cough. She is an ex-smoker with a 30-pack-year history. She has no constitutional symptoms or environmental pack-year history. She has no constitutional symptoms or environmental exposures. There is no history of cardiovascular disease. She was recently exposures. There is no history of cardiovascular disease. She was recently treated with several courses of oral antibiotics for “bronchitis.” On physical treated with several courses of oral antibiotics for “bronchitis.” On physical examination, no exanthem or joint abnormalities are apparent. Cardiac examination, no exanthem or joint abnormalities are apparent. Cardiac examination is normal. Bibasilar, coarse mid to end-inspiratory crackles are examination is normal. Bibasilar, coarse mid to end-inspiratory crackles are noted. Chest radiograph shows increased bibasilar reticular markings in the noted. Chest radiograph shows increased bibasilar reticular markings in the periphery that were not evident 3 years ago. Pulmonary physiology shows a periphery that were not evident 3 years ago. Pulmonary physiology shows a decreased total lung capacity (TLC), force vital capacity (FVC), and forced decreased total lung capacity (TLC), force vital capacity (FVC), and forced expiratory volume in 1 sec (FEV1), an increased FEV1/FVC ratio, and a expiratory volume in 1 sec (FEV1), an increased FEV1/FVC ratio, and a decreased diffusing capacity for carbon monoxide (DLCO). Which of the decreased diffusing capacity for carbon monoxide (DLCO). Which of the following tests is most likely to provide specific diagnostic and prognostic following tests is most likely to provide specific diagnostic and prognostic information?information?

A- Measurement of antinuclear antibodies and rheumatoid factor A- Measurement of antinuclear antibodies and rheumatoid factor B- Timed walk test with oximetry (6-minute walk test)B- Timed walk test with oximetry (6-minute walk test) C- High-resolution computed tomographic scan (HRCT) C- High-resolution computed tomographic scan (HRCT) D- Gallium scan D- Gallium scan E- Cardiopulmonary exercise testE- Cardiopulmonary exercise test

Case 6Case 6 A 53-year-old man is evaluated for a 6-month history of progressive dyspnea, A 53-year-old man is evaluated for a 6-month history of progressive dyspnea,

mild cough, and fatigue. He had been previously healthy and has never mild cough, and fatigue. He had been previously healthy and has never smoked. His medical history includes systemic hypertension diagnosed 18 smoked. His medical history includes systemic hypertension diagnosed 18 months ago, which is controlled with an ACE inhibitor. Results of his physical months ago, which is controlled with an ACE inhibitor. Results of his physical examination are normal. Chest radiograph and high-resolution computed examination are normal. Chest radiograph and high-resolution computed tomography show increased basal and peripheral predominant reticular lines tomography show increased basal and peripheral predominant reticular lines and moderate basal ground-glass opacity without honeycombing. Pulmonary and moderate basal ground-glass opacity without honeycombing. Pulmonary function studies show a forced vital capacity (FVC) of 73% of predicted and a function studies show a forced vital capacity (FVC) of 73% of predicted and a carbon monoxide diffusing capacity (DLCO) of 56% of predicted. Oximetry is carbon monoxide diffusing capacity (DLCO) of 56% of predicted. Oximetry is normal at rest, but desaturation to 84% is noted with brisk walking. What is normal at rest, but desaturation to 84% is noted with brisk walking. What is your diagnosis?your diagnosis?

A- Non specific pneumonitisA- Non specific pneumonitis B- AsthmaB- Asthma C- COPDC- COPD D- EmphysemaD- Emphysema E- Idiopathic pulmonary fibrosisE- Idiopathic pulmonary fibrosis

Case 7Case 7 An 18-year-old male high school football player is evaluated for recurrent An 18-year-old male high school football player is evaluated for recurrent

episodes of dyspnea, chest tightness, and cough that have occurred during a episodes of dyspnea, chest tightness, and cough that have occurred during a game and limited his ability to participate. The symptoms resolve game and limited his ability to participate. The symptoms resolve spontaneously in 20 to 30 minutes. The patient's father has known allergies spontaneously in 20 to 30 minutes. The patient's father has known allergies but no known lung disease. On physical examination, the patient is a healthy but no known lung disease. On physical examination, the patient is a healthy young man; the lungs are clear on auscultation. Office spirometry shows an young man; the lungs are clear on auscultation. Office spirometry shows an FEV1 of 90% predicted and FEV1/FVC 80%. Which of the following is the FEV1 of 90% predicted and FEV1/FVC 80%. Which of the following is the most appropriate next step in the evaluation of this patient?most appropriate next step in the evaluation of this patient?

A Measure lung volumes and diffusion capacityA Measure lung volumes and diffusion capacity BB Perform an exercise challenge test Perform an exercise challenge test C Perform allergy skin testing C Perform allergy skin testing D Prescribe a physical conditioning programD Prescribe a physical conditioning program

Case 8Case 8 A 44-year-old woman is hospitalized because of respiratory failure. She has A 44-year-old woman is hospitalized because of respiratory failure. She has

had flu-like symptoms with arthralgias, low-grade fever, cough, and rare had flu-like symptoms with arthralgias, low-grade fever, cough, and rare hemoptysis for 2 months. Respiratory failure developed during the past 48 hemoptysis for 2 months. Respiratory failure developed during the past 48 hours. Three days ago a chest radiograph revealed bibasilar alveolar hours. Three days ago a chest radiograph revealed bibasilar alveolar infiltrates. Physiology revealed an FVC 85% of predicted, FEV1 88% of infiltrates. Physiology revealed an FVC 85% of predicted, FEV1 88% of predicted, and a DLCO of 120%. On physical examination there is no predicted, and a DLCO of 120%. On physical examination there is no exanthem. Loud end-inspiratory bilateral crackles are heard. Mild anemia is exanthem. Loud end-inspiratory bilateral crackles are heard. Mild anemia is present. The PaO2 is 48 mm Hg, and the PaCO2 is 29 mm Hg. The current present. The PaO2 is 48 mm Hg, and the PaCO2 is 29 mm Hg. The current chest radiograph shows extensive bilateral infiltrative lesions. Intravenous chest radiograph shows extensive bilateral infiltrative lesions. Intravenous therapy with appropriate antibiotics for overwhelming community-acquired therapy with appropriate antibiotics for overwhelming community-acquired pneumonia is begun; 24 hours later respiratory failure continues. Which of the pneumonia is begun; 24 hours later respiratory failure continues. Which of the following is the best management option for this patient?following is the best management option for this patient?

A- Surgical lung biopsy A- Surgical lung biopsy B- CorticosteroidsB- Corticosteroids C- Bronchoscopy with bronchoalveolar lavageC- Bronchoscopy with bronchoalveolar lavage D- D- High-resolution computed tomography of the chestHigh-resolution computed tomography of the chest

Key pointsKey points

Along with PFT’s a good history and physical exam usually help Along with PFT’s a good history and physical exam usually help getting the right diagnosisgetting the right diagnosis

First look at the ratio First look at the ratio FEV1/FVC,FEV1/FVC, if if lowlow think think obstructive diseaseobstructive disease the the next step in that case is to assess for the severity of the obstruction next step in that case is to assess for the severity of the obstruction by looking at the FEV1 by looking at the FEV1

If If FEV1/FVCFEV1/FVC is is normal, normal, think either think either restrictive diseaserestrictive disease or or normal normal patternpattern. The next step is to check for the FVC, if . The next step is to check for the FVC, if FVCFVC is is lowlow the the diagnosis is diagnosis is restrictive diseaserestrictive disease. A . A normal FVCnormal FVC indicates a indicates a normal normal patternpattern

Finally when dealing with a Finally when dealing with a restrictive patternrestrictive pattern, a , a decreaseddecreased corrected corrected DLCODLCO indicates indicates parenchymal parenchymal disease were as a disease were as a normal corrected normal corrected DLCODLCO indicates indicates extra parenchymalextra parenchymal disease. disease.

Questions?Questions?