Review Of Respiratory Module

Question 1

If a patient is really ill and found to be hypoxaemic and hypercapnic, what could be the reasons?

Answer 1

1. Insufficient ventilation
   a. obstruction of airways
   b. failure to breathe properly
2. Insufficient gas exchange
   a. exchange surface dysfunction
   b. VQ mismatch
3. Insufficient oxygen carrying capacity
4. Insufficient oxygen in environment

Question 2

What would happen to the following in insufficient ventilation?

a. PaCO2?
b. Arterial pH?
c. PaO2?
d. CaO2 (arterial oxygen content)?
e. [Hb-O2]?
f. SaO2% ?
g. A-a gradient?

Answer 2

a. Increase
b. Decrease
c. Decrease
d. Decrease
e. Decrease
f. Decrease
g. Normal (because alveolar oxygen levels go down as well as blood oxygen levels go down - they go down by the same amount so the gradient is the same)

Question 3

What would happen to the following if there is insufficient oxygenation (problem with gas exchange)?

Answer 3

PaCo2= normal because carbon dioxide is still able to get out due to the different ways carbon dioxide and oxygen are transported. carbon dioxide transport is linear/unsaturatable whereas oxygen transport is saturatable.
Arterial pH= normal
PaO2= decrease
CaO2= decrease
[Hb-O2] = decrease
%SaO2= decrease
A-a gradient= increase because oxygen is in alveoli but can’t enter blood so there’s a high gradient

Question 4

What would happen to the following if there is insufficient oxygen carrying capacity (e.g anaemia)?

Answer 4

PaCO2= normal 
Arterial pH= normal 
PaO2= normal (as it’s in the plasma- not to do with haemoglobin)
CaO2= decrease
[Hb-O2]= decrease
%SaO2= normal
A-a gradient= normal

Question 5

What would happen to the following if there is insufficient oxygen in the atmosphere (altitude)?

Answer 5

PaCO2= decrease (due to reflex hyperventilation)
Arterial pH= increase
PaO2= decrease
CaO2= decrease
[Hb-O2]= decrease
%SaO2= decrease
A-a gradient= normal (as there is less oxygen in alveoli and blood by the same amount)

Question 6

What is respiratory failure?

Answer 6

PaO2 is smaller than 8kPa at when breathing air at sea level

Question 8

What is type 2 respiratory failure?

Answer 8

Causes:
Reduced ventilation (asthma, COPD, NMD, drug overdose, apnoea)

PAO2 = decreases
PaO2 = decrease
PaCO2 = increases 
pH = decrease

Question 9

What are the clinical signs/symptoms of respiratory distress?

Answer 9

1. Shortness of breath, tachypnoea, dyspnoea
2. Laboured breathing, audible lung sounds e.g wheezing due turbulent flow due to airway obstruction
3. Tiredness, drowsiness, loss of consciousness
4. Fatigue
5. Cyanosis

Question 10

Why would someone’s respiratory muscles not contract hence stop you breathe?

Answer 10

1. Motor neurone disease
2. Damage to brainstem e.g gunshot, stroke
3. Muscle wasting disease
4. Opioids

Question 11

How does carbon monoxide affect oxygen transport?

Answer 11

Carbon monoxide prevents oxygen binding to haemoglobin

Question 12

What happens to a patient that suffers respiratory failure and can’t obtain sufficient oxygen or expel sufficient CO2?

Answer 12

Oxygen starvation will cause tissue damage as they can’t aerobically respire - switch to anaerobic which doesn’t generate enough ATP and produces lactic acid

Question 13

Effects of insufficient oxygen oxygen supply

Answer 13

Clinical signs= dyspnoea, cyanosis, fatigue, coma, seizure
Acute = hypoxaemia —> tissue hypoxia e.g cerebral hypoxia —> organ failure —> death
Chronic = polycythaemia, hypoxic pulmonary vasoconstriction —> pulmonary heart failure

Question 14

Effects of insufficient carbon dioxide removal

Answer 14

Clinical signs: dyspnoea, confusion, seizure, unconsciousness
Hypercapnia —> acidosis —> organ failure + cardiac arrhythmia —> death

Question 15

What is type 1 respiratory failure?

Answer 15

Causes:
Reduced oxygenation (e.g altitude, VQ mismatch, pneumonia)

PAO2 = normal
PaO2 = decrease
PaCO2 = normal 
pH = normal