Spirometry

Question 1

What is recoil?

Answer 1

Ability to return resting volume once stretched

• lung recoil- inward force produced by the elastic properties of the alveoli; acts to collapse the lung
• Chest wall recoil (PCWR)- outward force produced by the chest wall

Question 2

What is intrapleural pressure?

Answer 2

• The pressure within the pleural cavity

- The opposing recoil forces of the chest wall and the lung creates a negative (subatmospheric) PIP

Question 3

What causes a negative intrapleural pressure?

Answer 3

A negative pleural pressure results from the elastic recoil of the lungs and chest wall pulling in opposite directions. The stretched lung (at the end of a normal expiration) tends to recoil inwardly, and the chest waLL tends to recoil outwardly, but in equal and opposite directions. Consequently, pleural pressure (PpI) b3comes negative (I.e., less than atmospheric pressure). Rupture or puncture of the lung or chest wall results in a pneumothorax, during which the trans pulmonary pressure becomes zero and elastic recoil causes the lung to collapse. The mediastinal membrane prevents the other lung from collapsing

Question 4

What is pneumothorax?

Answer 4

The presence of air or gas in the pleural cavity

Tension pneumothorax- cause a shift of the mediastinum and compromise hemodynamic stability

Causes:
Spontaneous
Traumatic

Question 5

What does spirometry do?

Answer 5

Measures lung volume

Question 6

What is tidal volume?

Answer 6

The volume of air inhaled or exhaled with each normal breath

Question 7

What is inspiratory reserve volume (IRV)?

Answer 7

The volume of air that can be inhaled at the end of a normal tidal inspiration

Question 8

What is expiratory reserve volume (ERV)?

Answer 8

The volume of air that can be exhaled after the end of a tidal exhalation

Question 9

What is residual volume?

Answer 9

The air remaining in the lungs after a maximal expiration (this volume of gas cannot be expelled, and cannot be measured by spirotremy)

Question 10

What is functional residual capacity (FRC)?

Answer 10

The total volume of air remaining in the lungs at the end of a tidal exhalation

Question 11

What is the total lung capacity?

Answer 11

The volume of air in the lungs at the end of a maximal inspiration

Question 12

What is the vital capacity?

Answer 12

The volume of air exhaled from maximal inspiration to maximal exhalation; maximum expiration. When done with force this volume is termed the forced vital capacity (FVC)

Question 13

What is forced expiratory volume in 1 second(FEV1)?

Answer 13

The volume of air exhaled in the first second of a FVC test

Question 14

What is the purpose of FEV and FVC1?

Answer 14

From total lung capacity there is forceful exhalation into the spirometer

Measurements of FVC, FEV1 and FEV1/FVC ratio are obtained and restrictive disorders

Question 15

What is an obstructive disorder?

Answer 15

expiratory flow rate is significantly decreased resulting in decreased FEV1 and FVC

-The FEV1/FVC ratio is low

Question 16

What is a restrictive disorder?

Answer 16

Lung inflation is decreased resulting in decreased FEV1 and FVC

The FEV1/FVC ratio is normal or increased

Question 17

W(at is a normal FEV1/FVC ratio?

Answer 17

4.5/5.5L*100= about 80%

Question 18

Explain the use of FEF25-75

Answer 18

Forced expiratory flow(FEF)

Represents the expiratory flow rate over the middle half of the FVC (between 25% and 75%)

Small airway obstruction may be present even when the FEV1/FVC is above the lower limit of normal

FEF25-75 has the greatest sensitivity for the deduction of early airflow obstruction

Question 19

What happens in FEV1/FVC in restrictive lung disease?

Answer 19

Both FEV1 & FVC is reduced

The FEV1/FVC ratio remains normal or may be increased

Question 20

What happens in FEV1/FVC obstructive lung disease?

Answer 20

FEV1 is reduced significantly

FVC is reduced

FEV1/FVC ratio is below 0.8

Question 21

Summarize obstructive disease

Answer 21

Expiratory flow rate decreased

Airway occlusion, air trapping

Examples:

1. Chronic bronchitis
2. Emphysema
3. Asthma

Question 22

Summarize restrictive lung diseases

Answer 22

Lung inflation is decreased

Intrinsic- lung tissue
Extrinsic - chest wall, pleura or neuromuscular

Examples:

1. Pulmonary fibrosis
2. IRDS
3. Scoliosis

Question 23

What is emphysema ?

Answer 23

Disintegration of the lungs elastic framework and destruction of alveolar

Enlargement of air spaces distal to the terminal bronchioles

Signs of air trapping- prolonged expiratory phase, barrel chest, flat diaphragm

Commonly caused by cigarette smoking

Genetic risk factor- alpha-1-antitrypsin (AAT) deficiency

Question 24

Contrast main difference in flow volume loops in restrictive and obstructive lung diseases

Answer 24

Obstructive lung volumes> normal (increased TLC, FRC, RV); restrictive lung volumes < normal. In obstructive, FEV1 is more dramatically reduced compared with FVC —> decreased FEV1/FVC ratio. In restrictive, FVC is more reduced or close to same compared with FEV1–> increased or normal FEV1/FVC ratio

Question 25

What is independent effort portion of the flow volume loop?

Answer 25

Despite varying effort of exhalation the latter parts of the curves all merge

Question 26

Explain effort dependence/independence

Answer 26

The curve is effort dependent until PEF is achieved Regardless of effort the flow after PEF is limited due to compressed airways (effort independence) Dynamic Compression of Airways increases resistance to airflow This effect is magnified in lungs with low elastic recoil (high compliance)- airways are floppy and the lung recoil does little to augment airway pressures above +ve intrapleural pressure during forced expiration

Question 27

What is COPD?

Answer 27

Combination of chronic bronchitis, emphysema and asthma The most common chronic lung disease in the US Commonly caused by cigarette smoking The classical feature is decreased airflow due to chronic obstruction of the small airways Results in a decrease in FVC, FEV1 and FEV1/FVC ratio In severe cases air is trapped in the lungs during forced expiration

Question 28

What is a peak flow device?

Answer 28

Used for monitoring lung disease Provides information about exacerbations Objective data is collected the practitioner

Question 29

What is Helium dilution technique?

Answer 29

Useful in healthy individuals with no lung obstruction Helium doesn’t get beyond obstruction, thus yielding a false FRC Body plethysmography Known concentration of helium in a known volume of gas (oxygen) in spirometer Person is asked to breathe until the gas equilibrates between the spirometer & the lungs C1 x C2= C2 x (V1 + V2) From this V2= FRC/RV/TLC (depending on starting time)

Question 30

What is a Body Plethysmograph?

Answer 30

Body box Airtight box that measures changes in pressure and volume on inspiration and expiration Boyles law is used to estimate lung volume

Question 31

What does Body Plethysmograph measure?

Answer 31

Measures functional residual capacity. The subject sits in an airtight box and breathes air through a mouthpiece. The mouthpiece is closed at the end of a normal expiration, and the subject continues to try to breathe against a closed mouthpiece. P1 is the lung pressure at the end of expiration and P2 at the end inspiration. 🔼V is the volume change accompanying inspiration and expiration; It results from changes in thoracic volume against a closed mouthpiece. The body plethysmograph is used clinically for measuring FRC in patients in patients with airway obstruction

Question 32

Contrast patient demographic for COPD and Asyhma

Answer 32

Age of onset: COPD- above 35, asthma- any age Onset of dyspnea: COPD- gradual asthma- sudden Productive cough: COPD- years asthma- with attack Childhood wheeze: COPD- uncommon. asthma- common Family history: COPD- uncommon asthma- common Smoking history: COPD- yes Asthma- variable

Question 33

Contrast FEV1 and FVC stats in COPD and asthma

Answer 33

FEV1 & FVC: COPD- reduced asthma- reduced during an attack FEV1:FVC: COPD- reduced asthma- reduced during an attack VC: COPD- reduced asthma- nearly normal Response to steroids and bronchodilator: COPD- minimal asthma- strong