L 06 Lab test of Asthma

Question 1

Define breathing, inspiration and expiration

Answer 1

Respiration is the act of breathing (gas exchange between an organism and its environment)
Inhaling is taking in oxygen
Exhaling is giving off carbon dioxide

Question 2

What are the 4 functions of gas exchange?

Answer 2

Ventilation, capillary blood flow, diffusion of gases, of gases by blood.

Question 3

Define ventilation and explain how it occurs

Answer 3

Ventilation is cyclical movement of air into and out of the lungs.
Occurs via contraction and relaxation of respiratory muscles using the elastic recoil of connective tissue in the lungs.

Question 4

Define the diffusion of gases and explain how it occurs

Answer 4

The movement of O2 and CO2 from the alveolar space across into the blood. Occurs via a concentration gradient

Question 5

Explain the importance of capillary flow

Answer 5

An adequate capillary flow to the lungs is required for adequate gas exchange, to maintain the concentration gradient.

Question 6

How are gases carried in the blood? How are they released?

Answer 6

CO2 and O2 are bound to Hb and released by a pressure gradient.

Question 7

Define alveolar ventilation

Answer 7

The movement of gas from the lungs to the blood (basically diffusion)

Question 8

What factors can affect ventilation?

Answer 8

Any disease that inhibits elastic recoil can affect ventilation

• e.g obstructive diseases (asthma, COPD) affect inspiratory rate
• e.g restrictive diseases (pulmonary fibrosis) affect inspiratory capacity

Question 9

Examples of obstructive diseases

Answer 9

Asthma, COPD, bronchitis, (emphysema)

Question 10

Examples of restrictive diseases

Answer 10

Pulmonary fibrosis, interstitial lung disease

Question 11

Diseases that affect gas diffusion

Answer 11

Pneumonia (difficulty reaching alveolar space)
A tumour (cannot diffuse as easily across the alveolar space)

Question 12

Diseases that affect pulmonary capillary flow

Answer 12

Pulmonary embolism

Right ventricular dysfunction.

Question 13

What are the Factors that affect Hb?

AWhat affect O2 binding to Hb?

Answer 13

Anemia and blood loss affect hemoglobin

Arterial pH and carBon moNoxide affect O2 binding to Hb

Question 14

What are hypoxia and anoxia. When may these happen?

Answer 14

Hypoxia- Low Oxygen in tissues.
Anoxia- No Oxygen in tissues.
May happen if any of the 4 respiratory elements are affected.

Question 15

What effect will giving an oxygen mask to someone with respiratory problems have?

Answer 15

It will only help if ventilation is the problem (pure O2 vs air). Excess oxygen will not help diffusion occur.

Question 16

Changes in which two measures cause a change in respiratory rate?

Answer 16

PaCO2 and PaO2 (pressure of arterial CO2 and O2)

Question 17

What respiratory functions can we measure (x7)? Which can we calculate?

Answer 17

• Respiratory rate, pH, SaO2 (%), PaO2, PaCO2, Hb, Inspired O2
• CaO2 (arterial Oxygen content) can be calculated

Question 18

Rapid breathing is due to…

Answer 18

Low CaO2 (arterial oxygen content)
High PaCO2 (partial pressure of CO2)

Question 19

What is FEV1 and what is it’s unit? What is it dependent on? Usual value?

Answer 19

FEV1: measure of the Forced expiratory volume in 1 second from the lungs.
Unit: L/s
Dependencies: size, age, sex
Usual value: 80%

Question 20

What is FVC and what is it’s unit? What is it dependent on? Usual value? What needs to be

Answer 20

FVC: measure of the vital capacity of the lungs. Is a fraction of the total lung volume.
Unit: L
Dependencies: size, age, sex
If lung elasticity is normal then FVC is close to the true vital capacity.

Question 21

What is the normal FEV1:FVC ratio? and what does this mean?

Answer 21

80% of the capacity of my lungs can be eliminated in a single second.

Within 5% of the predicted ratio

Question 22

Unit for PEFR(Peak expiratory flow rate)?

What are the normal values dependent on?

What can affect PEFR?

Answer 22

(L/min)

Age, height and weight are the main factors which affect the Peak Expiratory Flow Rate (PEFR),

Forced Expiratory Volume in the first second (FEV1) and Forced Vital Capacity (FVC) also affect the Rate of (PEFR),

Scores range between around 400 and 700 liters per minute, although scores in older women can be lower and still be normal.

Question 23

What are the normal values dependent on for PEFR?

Answer 23

Peak expiratory flow rate = L/min
More sensitive to large airway diseases (narrowing = more significant)
Dependencies: size, age, sex

Question 24

How do obstructive diseases affect spirometry? And which part of FEV1:FVC do they affect? What happens therefore to the overall ratio?

Answer 24

Obstructive diseases reduce expiration ability (therefore affect FEV1)
By reducing one part of the ratio, the whole ratio decreases.

Question 25

How do restrictive diseases affect spirometry? And which part of FEV1:FVC do they affect? What happens therefore to the overall ratio?

Answer 25

Restrictive diseases reduce the usable capacity of the lungs, therefore decreasing FVC. As vital capacity is reduced, so is total capacity. Both FEV1 and FVC will therefore decrease,

Question 26

What is the difference between an obstructive and restrictive lung disease?

Answer 26

Obstructive: conditions that make it hard to exhale all the air in the lungs. Restrictive: make it difficult to fully expand lungs with air

Question 27

What does spirometry measure? (Spirometry:(spy-ROM-uh-tree) is a common office test used to assess how well your lungs work by measuring how much air you inhale, how much you exhale and how quickly you exhale)

Answer 27

Alveolar ventilation

Question 28

Does the carriage Hb of gases affect PaO2 or PaCO2? Do changes in ventilation?

Answer 28

No, changes in Hb do not affect PaO2 and PaCO2 | Changes in ventilation affect both PaCO2 and PaO2

Question 29

PaO2 definition and normal value. Values less than .... typically cause symptoms. Dependencies?

Answer 29

The pressure of O2 in the arterial circulation. Normal value: 100mmHg Values less than 60mmHg typically cause symptoms Dependent on O2 inspired and atmospheric pressure

Question 30

PaCO2 definition and normal value. Values less than ... typically cause symptoms. How is PaCO2 produced?

Answer 30

The pressure of CO2 in the arterial circulation. Normal values: 40mmHg Values less than 38- 42mmHg typically cause symptoms. A higher PaCO2 level indicates acidosis while a lower PaCO2 level indicates alkalosis. CO2 is produced by tissues during the internal respiration

Question 31

What do arterial gases measure?

Answer 31

The influence of ventilation and diffusion at the alveolar space and capillary flow

Question 32

What 2 systems tightly control the blood pH? pH governed by the balance between....?

Answer 32

Renal and respiratory systems. pH governed by the balance between HCO3(Bicarbonate) and PaCO2

Question 33

An increase in PaCO2 causes a .... in pH and therefore.....

Answer 33

An increase in PaCO2 causes a decrease in pH and therefore O2 dissociates from Hb

Question 34

Normal pH value, acidosis value and high-risk pH value of the blood

Answer 34

Normal = 7.4 Acidosis = < 7.35 High risk = < 7.0

Question 35

What is hypercapnia?

Answer 35

excess carbon dioxide in the blood (increased PaCO2)

Question 36

O2 binding is affected if there is a ... in RBCs. + examples (x4)

Answer 36

O2 binding is affected if there is a decrease in RBCs | e.g: anaemia, blood loss, chronic renal failure, CO poisoning

Question 37

A decrease in RBCs .... affects the pressure and conc of arterial O2. RBC values less than ...

Answer 37

typically cause symptoms A decrease in RBCs DOES NOT affect the pressure and conc of arterial O2. RBC values less than 80g/L typically cause symptoms

Question 38

What is Sa02? Normal value? Symptomatic value? What is SaO2 affected by? A reduction in pH causes...

Answer 38

SaO2 represents the % of Hb that is saturated with O2 Normal values: >95-98% on room air. <90% = symptoms SaO2 is affected by anything that affects PaO2 and pH (i.e O2 to Hb binding is dependent on pH, so a reduction in pH will reduce O2 bound)

Question 39

What is CaO2? What does it represent? Normal values? How is it measured?

Answer 39

CaO2 = arterial concentration of O2 CaO2 provides a measure of the arterial O2 concentration which drives tissue oxygenation. Normal values: 16-20 (mL/100mL) Is not measured, is calculated

Question 40

What happens to PaO2 during ventilation disorder, pH imbalance, and anemia?

Answer 40

Ventilation disorder: PaO2 decreases (less inspired = decreases) pH imbalance: PaO2 stays the same Anemia: PaO2 stays the same

Question 41

What happens to SaO2 during ventilation disorder, pH imbalance, and anemia?

Answer 41

Ventilation disorder: decreases (as PaO2 is decreased) pH imbalance: decreases (less binding) Anaemia: SaO2 stays same

Question 42

What happens to CaO2 during: a ventilation disorder, pH imbalance, and anaemia?

Answer 42

Ventilation disorder: decreases (less present) pH imbalance: decreases (less bound) Anemia: decreases (less produced)

Question 43

What is the body's goal in terms of respiration?

Answer 43

To maintain tissue oxygenation

Question 44

What affect does asthma have on the body and what does the body do to respond to this?

Answer 44

Asthma = ventilation decrease = reduces arterial and therefore tissue oxygenation. Body's response: Short term = increases HR to increase cardiac output.