Pulmonary Function Tests Flashcards
measures available air
Forced Vital Capacity (FVC)
Components of FVC
ERV +IRV + tidal volume
Normal FVC
~4 Liters in 25 y/o male (declines ~ 30 ml/ year)
Components of TLC
TV + IRV + ERV + RV
3 components PFTs assess
Lung volumes, Lung air flow, and Lung diffusion capacity
Obstructive lung disease characteristic
“air trapping” - more time spent exhaling trapped air
inspiratory:expiratory ratio= 1:4
Device to assess expiratory function
Peak Expiratory Flow meter
- measures personal best
Assessing results of flow meter
1. Green “Zone”: 80- 100% of personal best 2. Yellow Zone 50- 79% of personal best ( Requires Rescue Medications) 3. Red Zone < 50% of personal best (Rescue medications \+ Call doctor)
Normal PEF
500- 700L/ min= based on Age & body height or Personal Best
Measures only air flow not volume
Air Flow Tests (on expiration)
Uses of Air Flow Tests
Helps classify pulmonary disease severity
Used for Daily monitoring of disease (i.e. asthma)
Measures Peak Expiratory Flow Rate(PEFR) and Forced Expiratory Volume (FEV)
Spirometry
- Displayed as Flow Volume loop
Measured first milliseconds of max expiratory efforts
(extrapolated into Liters/sec)
Must establish baseline* based on age, gender, and height
Peak expiratory flow rate
- not based on personal best
Measures volume of air movement
Must establish baseline Compared with “predicted” FEV1 - Based on age, gender, height
Forced Expiratory volume (FEV1)
Role of FEV1
Categorize Pulmonary disease severity
Identifies Progression of disease
Not used for daily monitoring
TD is a 28 y/o male with 2 weeks of worsened asthma control. TD reports using his rescue inhaler daily.
TD would like to monitor the severity of his asthma episodes.
Which of the following are most useful for TD?
FEV1 with Spirometry
FVC with Spirometry
PEFR with Peak flow meter
PEFR with Spirometry
PEFR with Peak flow meter
Identifies the presence of lung damage related to diffusion
This is damage directed at the alveolar-capillary oxygen exchange
Lung Diffusion Capacity
(Perfusion)
- Identifies pulmonary fibrotic changes (of alveoli)
Technique of DLCO calculated and purpose of test
Known amount of CO is inhaled & hold breath X 10 sec
Measure CO on expiration (compared with inspiration)
Measures degree of reduction from baseline (i.e. > 20%) - suggests significant pulmonary fibrosis
Used to Identify conditions disrupting diffusion
Clinical Use of Pulmonary Function tests
Screen & diagnosis respiratory disease
Identifying the type of pulmonary disease
Evaluation of pulmonary disease severity
Monitor pulmonary function
Beneficial Response: Response to therapy
Adverse Response: Onset of pulmonary toxicity (i.e. Drugs, radiation)
2 Types of pulmonary diseases
Obstructive pulmonary disease
Restrictive pulmonary disease
FEV1/ FVC < 70% = Diagnositic
Obstructive
Impedance to airflow due to airway resistance
Decreased diameter of airways (bronchials)
COPD and Asthma
Reduction in elastic recoil (alveoli)
emphysema
Findings of Asthma on spirometry testing
Normal FVC Decreased FEV1 Decreased FEV1:FVC Increased TLC Increased residual volume Normal diffusion capacity Dynamic Hyperinflation
Findings on COPD on spirometry testing
Normal FVC Decreased FEV1 Decreased FEV1:FVC Increased TLC Increased residual volume Decreased diffusion capacity (<70%) Dynamic hyperinflation
Lungs are restricted in amount of air they contain
Due to Reduced compliance and/or Lung size
Restrictive pulmonary disease
Sources of Restrictive lung disease
Intrinsic or Extrinsic causes
Intrinsic Restrictions
Pulmonary fibrosis
Sarcoidosis
Lung Cancer
Extrinsic Restrictive
Loss of lung volume (e.g., pleural effusions= extrinsic) Extrathoracic compression (e.g., morbid obesity= extrinsic)
Findings on Intrinsic Restrictive on spirometry testing
Decreased FVC Decreased FEV1 Increased FEV1:FVC Decreased TLC Decreased RV Decreased diffusion capacity
Findings on Extrinsic Restrictive on spirometry testing
Decreased FVC Decreased FEV1 Increased FEV1:FVC Decreased TLC Decreased RV Normal diffusion capacity
RC is a 55 y/o male with cancer treated with Bleomycin (3rd cycle of chemotherapy) who complains of worsened cough and dyspnea for 4 weeks.
No fevers, no elevated WBCs; CXR = diffuse infiltrates
(+) Tobacco= None
Pulmonary function tests:
FEV1= 2.5 L (Predicted = 3.5L);FVC = 3.0 L (Predicted = 5.5L)
RV = 3.0 L (Predicted at 2.0 L); DLCO= 30% decrease (baseline)
Which of the following does this patient exhibit?
Obstructive airway disease
Restrictive airway disease (intrinsic cause)
Restrictive airway disease (extrinsic cause)
Restrictive airway disease (intrinsic cause)
BT is a 22 y/o female with a chronic cough and increasing shortness of breath for the past 3 months. BT claims her symptoms improve on weekends.
Started new job at Tyson Chicken processing plant (5 mths ago)
(+) Tobacco= 7 pack year history
Pulmonary function tests:
FEV1= 2.5 L (Predicted = 4L);FVC = 5.5 L (Predicted = 6L)
RV = 2.5 L (Predicted at 2.0 L); DLCO= Normal
Which of the following does this patient exhibit?
Obstructive airway disease
Restrictive airway disease (intrinsic cause)
Restrictive airway disease (extrinsic cause)
Obstructive airway disease
