Resp 02: Spirometry

Front 1

What is the volume of air inhaled during a normal inhalation?

Back 1

Tidal Volume (Vt)

Front 2

What is the maximum amount of air that can be inhaled beyond the tidal volume?

Back 2

Inspiratory Reserve Volume

Front 3

What is the maximum amount of air that can be exhaled beyond the tidal volume?

Back 3

Expiratory Reserve Volume

Front 4

What is the amount of air that can not be exhaled from the lungs?

Back 4

Residual Volume

Front 5

What is the term for the amount of air that can be inhaled after a normal exhalation?

Back 5

Inspiratory Capacity = Inspiratory Reserve Volume + Tidal Volume

Front 6

What is the term for a maximal inspiration after exhaling all of your air?

Back 6

Vital Capacity = Inspiratory Reserve Volume + Tidal Volume + Expiratory Reserve Volume

Front 7

What is the term for the amount of air remaining in the lungs after a normal exhalation?

Back 7

Functional Residual Capacity = Expiratory Reserve Volume + Residual Volume

Front 8

What is the term for all of the air in the lungs after a maximal inspiration?

Back 8

Total Lung Capacity = Inspiratory Reserve Volume + Tidal Volume + Expiratory Reserve Volume + Residual Volume

Front 9

How do you calculate the trans-pulmonary pressure?

Back 9

Ptp = Palv - Ppl
Transpulmonary Pressure = Alveolar Pressure - Pleural Pressure

Front 10

What is the sequence of events during inspiration?

Back 10

1. Diaphragm and inspiratory intercostals contract
2. Thorax expands
3. Pleural pressure becomes subatmospheric
4. Transpulmonary pressure increases
5. Lungs expand and pulls open alveoli
6. Alveolar pressure becomes subatmospheric (negative)
7. Air flows into alveoli

Front 11

What happens to the alveolar pressure during inspiration and expiration?

Back 11

- Negative during inspiration (draws air in)
- Positive during expiration (pushes air out)

Front 12

What happens to the pleural pressure during inspiration and expiration?

Back 12

Always negative
- Becomes more negative during inspiration
- Returns to normal (less negative) during expiration

Front 13

What happens to the the transpulmonary pressure during inspiration and expiration?

Back 13

- Ppl is negative at the onset of inspiration, and becomes more negative to generate a negative Palv

- The differences between the two (Ptp) increases during inspiration

- There is a greater net change in Ppl for a given change in Palv during inspiration

- This occurs because the lungs are elastic structures, and there is a requirement for greater force to overcome those opposing forces

- This is also reflected in the fact that expiration is (mostly) passive, due in large part to the elastic recoil of the lung

- During expiration, Ptp ultimately gets smaller

Front 14

What determines airflow, particularly during expiration?

Back 14

Flow = (Palv - Patm) / airway resistance

- As Palv increases, flow increases
- As airway resistance increases, flow decreases

Front 15

Where is airway resistance greatest?

Back 15

Medium sized bronchi in the conducting zone

Front 16

Where is airway resistance lowest?

Back 16

- Respiratory Zone (alveoli)
- For conducting zone it is lowest in the terminal bronchioles due to the vastly greater total cross-sectional area at the end of the “tree”

Front 17

How does lung volume affect airway resistance?

Back 17

As lung volume is increased, total airway resistance decreases d/t overall increase in total airway diameter

Front 18

When is total airway resistance highest?

Back 18

At low lung volumes, which contributes to the hysteresis of the pressure-volume relationship (see next slide)

Front 19

What is the inverse of resistance? How is it affected by increased lung volumes?

Back 19

- Conductance is the inverse of resistance
- Increases with increased lung volumes

- Lung compliance can be calculated as the change in lung volume (ΔV) for a given change in transpulmonary pressure (ΔPtp)
*Compliance=ΔV/ΔPtp.

Front 20

How does the amount of elastic recoil relate to compliance?

Back 20

- Elastic recoil of the lung is a mechanical property of the lung and is not physiologically regulated
- It is also conceptually the inverse of lung compliance
- The more elastic recoil the lung has, the less compliant

Front 21

What happens to the (static) pressure-volume relationship in Emphysema?

Back 21

- Emphysema is a disease caused by breakdown of the lung tissue, largely due to a combination of factors (chronic inflammation/irritants like cigarette smoke)

- Tissue breakdown leads to reduced lung elasticity (increased compliance) among other factors such as airway narrowing which increases airway resistance

Greater slope = increased lung compliance

Front 22

What happens to the (static) pressure-volume relationship in Fibrosis?

Back 22

- Fibrosis is a type of interstitial lung disease in which irritants lead to an exchange of healthy lung tissue with fibrotic tissue (scarring)
- This leads to increased tissue elasticity (reduced lung compliance), and lung volume limitations

Lower slope = reduced lung compliance

Front 23

If we hold airway resistance constant, what is airflow proportional to?

Back 23

Alveolar Pressure we can generate (which is effort dependent)

Front 24

What do A, B, and C represent?

Back 24

- If you inhale maximally to TLC and force expire maximally, there is an effort dependent phase and an effort independent phase.
- Shown in this figure is the relationship between lung volume expired (starting at TLC and exhaling to residual volume) and the resulting exhaled airflow

- A is generated at 100% effort
- B is generated at 75% effort
- C is generated at 50% effort

- Notice also that as you exhale more volume, the three volume-flow curves come together (around 4 liters of expired volume), demonstrating that no matter what your level of effort expired flow is the same (effort-independent phase)

Front 25

What do the big arrows represent in this image? Outcome?

Back 25

- Maximum effort (inward on the chest wall)
- Generates a large, positive plural pressure (+30 in this example)

Front 26

What leads to a positive pressure in the alveolar spaces (+40)? What happens?

Back 26

- Maximum effort of exhaling generates a large positive pleural pressure
- Combined with the natural elastic recoil tendency of the lung tissue creates an even greater positive pressure in the alveolar spaces (+40)
- Because alveolar pressure far exceeds atmospheric pressure there is AIRFLOW OUT OF LUNG

Front 27

What happens as air flows out of the lungs (d/t positive alveolar pressure?

Back 27

- As the airflow passes along through the airways, and as the lung volume decreases there is INCREASING airway RESISTANCE
- Increasing resistance REDUCES the net airway pressure
- Creates a pressure gradient from the alveolus to the conducting airways

Front 28

What happens as the airway pressure decreases?

Back 28

- As the airway pressure decreases it eventually reaches a point within the pleural cavity where the external positive pressure (+30) exceeds the airway pressure (+25 at the end of the airway in this figure)
- This leads to the airway tending to COLLAPSE
- This collapse in turn creates GREATER RESISTANCE to airflow, and the collapsibility of the airway is highly dependent upon lung compliance

Front 29

What are the indications for Pulmonary Function Testing?

Back 29

- Used when signs/symptoms/lab tests suggest an abnormality in lungs
- Need to determine if they are functioning properly
- Helps us to determine the etiology
- Also helps to assess the effects of disease and therapies

Front 30

When would you use Pulmonary Function Testing as a screening tool?

Back 30

- Smokers
- Occupational exposures
- Preoperative risk
- Disability
- Prognosis

Front 31

What values are assessed in Spirometry / PFTs?

Back 31

- FEV1
- FVC

Front 32

What is FEV1?

Back 32

Forced Expiratory Volume in 1 second (maximum air you can exhale in 2 second)

Front 33

What is FVC?

Back 33

Forced Vital Capacity (maximum air you can exhale from total lung capacity)

Front 34

What is this kind of expiratory flow volume loop indicative of?

Back 34

Obstructive disease: scalloped / concave

Front 35

What disease process would make the expiratory flow volume loop smaller and at a lower volume than normal?

Back 35

Restrictive disease

Front 36

Will Obstructive or Restrictive disease have a higher lung volume?

Back 36

Obstructive disease has a larger volume than normal at maximum inhalation

Restrictive disease has a smaller volume than normal at maximum inhalation

Front 37

What is this kind of expiratory flow volume loop indicative of?

Back 37

Fixed Large Airway Obstruction:
- Exhalation and inhalation curves are shallower than usual

Front 38

What is this kind of expiratory flow volume loop indicative of?

Back 38

Extrathoracic Disease (e.g., vocal cord paralysis, goiter, etc.)
- Issue with inhalation (extrathoracic airways are smaller on inhalation)

Front 39

What is this kind of expiratory flow volume loop indicative of?

Back 39

Intrathoracic Disease
- Issue with exhalation (intrathoracic airways are smaller in exhalation)

Front 40

What are the keys to interpreting spirometry?

Back 40

- Look at FEV1/FVC ratio, FEV1, and FVC
- Always look at FEV1/FVC ratio first
- FEV1/FVC <95% expected is abnormal = Obstruction
- FVC <80% expected is abnormal = Restriction

Front 41

What does it tell you if the FEV1/FVC ratio is >95% of the predicted value (ratio: 0.70-0.87)?

Back 41

Either NORMAL or RESTRICTIVE (would cause both FEV1 and FVC to be proportionally lower making ratio seem normal)

Front 42

What does it tell you if the FEV1/FVC ratio is <95% of the predicted value?

Back 42

Obstructive process

Front 43

What does it tell you if the FVC <80% of the predicted value?

Back 43

Restrictive Lung Disease

Front 44

How do you rank the Obstructive Ventilatory Defects?

Back 44

Based on % of Predicted FEV1:
- >99%: physiologic variant
- 70-99%: mild
- 60-69%: moderate
- 50-59%: moderately severe
- 34-49%: severe
- <34%: very severe
Obstructive Ventilatory Defect

Front 45

What should you do for all patients w/ spirometry showing low FEV1/FVC ratio?

Back 45

Bronchodilator Responsivity Testing:
- A significant response to a bronchodilator is shown when the FVC or FEV1 increases at least 12% and 200 mLs

Front 46

What would indicate a positive bronchodilator responsivity test? When would you order this test?

Back 46

- FVC or FEV1 increases at least 12% and 200 mLs

- Do for all patients w/ spirometry showing low FEV1/FVC ratio
- Do for all patients suspected of asthma or chronic obstructive lung disease

Front 47

What can cause obstructive ventilation in the large conducting airways?

Back 47

- Tumors
- Foreign bodies

Front 48

What can cause obstructive ventilation in the peripheral airways?

Back 48

- Asthma
- Chronic Bronchitis
- Cystic Fibrosis

Front 49

What can cause obstructive ventilation in pulmonary parenchymal disease?

Back 49

Emphysematous changes from cigarette smoking

Front 50

What can cause restrictive ventilatory defects?

Back 50

- Interstitial lung disease: sarcoidosis, collagen vascular disease, pulmonary fibrosis
- Pneumonectomy (surgical removal of one lung)
- Pleural disease: pleural effusion
- Chest wall disease: kyphosis, neuromuscular disorders
- Extrathoracic conditions: obesity, ascites, pregnancy

Front 51

What is the true hallmark of a restrictive ventilatory defect?

Back 51

Reduced Total Lung Capacity

Front 52

How do you rank the Restrictive Ventilatory Defects if a patient has a normal FEV1/FVC ratio and a decreased FVC?

Back 52

Based on % of Predicted TLC:
- >70%: Mild
- 60-69%: Moderate
- <60%: Moderately Severe
Restrictive Ventilatory Defect

Front 53

How do you rank the Restrictive Ventilatory Defects if you cannot obtain lung volumes?

Back 53

Grade FVC via the obstructive FEV1 criteria
Based on % of Predicted FEV1:
- >99%: physiologic variant
- 70-99%: mild
- 60-69%: moderate
- 50-59%: moderately severe
- 34-49%: severe
- <34%: very severe
Restrictive Ventilatory Defect

Front 54

If the FEV1/FVC ratio is normal and the TLC is low and you are following the FVC to assess Restrictive Lung Disease, how do you rank the severity?

Back 54

Degree of restriction is based upon the percent of predicted FVC:
- 70-79%: Mild
- 60-69%: Moderate
- 50-59%: Moderately Severe
- 34-49%: Severe
- <34%: Very Severe
Restrictive Ventilatory Defect

Front 55

What can the FEF50/FIF50 ratio tell you?

Back 55

- < 1.0: Normal
- > 1.0: Variable Extrathoracic Airway Obstruction
- A little > 1.0: Fixed Extrathoracic Airway Obstruction

Front 56

What makes a spirogram (spirometry test) acceptable?

Back 56

- Free from artifacts such as cough or early termination
- Good start: extrapolated volume is <5% of FVC or 0.15 L, whichever is greater or time to PEF is < 120 ms
- Satisfactory exhalation: 6 second of exhalation and/or a plateau int eh volume-time curve

Front 57

What makes a spirogram (spirometry test) repeatable?

Back 57

- After 3 acceptable spirograms: are the 2 largest FVCs within 0.2L of each other? Are the 2 largest FEV1s within 0.2L of each other?
- If both of these criteria are not met, test until: both are met or a total of 8 tests
- Save the 3 best maneuvers

Front 58

What is wrong with this spirogram?

Back 58

Patient hesitated at the start of the flow-volume loop: kink in curve

Front 59

What is wrong with this spirogram?

Back 59

Start is too slow: the peak is not within the first 100 ms and there is a dent in the loop

Front 60

What is wrong with this spirogram?

Back 60

Incomplete expiration: a sudden drop at the right end of the loop, the loop is cut off

Front 61

What is wrong with this spirogram?

Back 61

Coughing during forced expiration: the loop is interrupted because of a sudden stop of flow

Front 62

Case: A 25 year old woman who is 9 months pregnant and has a history of well-controlled asthma comes into the ED complaining of SOB and labor pains - lung examination shows some basilar rales that clear with cough and deep inspiration.

What would you expect her spirogram to look like?

Back 62

Restrictive Lung Disease:
- Shape normal
- Low FVC

Front 63

Case: A 45 yo man who was in a car accident 4 years ago and suffered major blood loss and a respiratory arrest at the scene, who last month had an allergic reaction to a bee sting that required the EMS to insert an endotrachial tube to maintain his airway- he comes into the office with worsening exercise intolerance and “wheezing”.

What would you expect his spirogram to look like?

Back 63

Extrathoracic Airway problem causes problems with inspiration
- FEF50 > FIF50

Front 64

Case: A 65 year old woman who comes into your office for a routine visit who has smoked a pack a day of cigarettes since she was 18 and has no complaints of SOB with routine activities, but when she carries groceries up the stairs she has chest tightness and sweating – lungs show no wheezes, rhonchi or rales.

What would you expect her spirogram to look like?

Back 64

She has no pulmonary issues that we can tell right now, so she should have a normal spirogram

Front 65

Case: A 6 yo boy who gets recurrent colds that settle into his chest 2 times a year comes into the office for a back-to-school check-up – his mother feels he is doing well now that he is not sick and would not like for him to have any inhalers for fear of him being stigmatized by the other children – he is quiet but breathing comfortably reading a book, his lungs show a prolonged expiratory phase and occasional wheezing.

What would you expect her spirogram to look like?

Back 65

Obstructive Ventilatory Disease (Asthma):
- Concave expiratory phase (because problem emptying the smaller airways