Lecture 1

Question 1

Define Respiratory Failure

Answer 1

1. Patient loses the ability to ventilate adequately

2. Patient can’t deliver enough O2 to the blood and organs

Question 2

Define hypoxaemic RF with regards to:

1. PaO2

2. PaCO2

Answer 2

Type 1
O2 movement impairment
PaO2 < 60 mmHg
PaCO2 < 42 mmHg

Question 3

Define hypercapnic RF with regards to:

1. PaCO2

2. The respiratory pump

Answer 3

1. PaCO2 > 50 mmHg

2. Respiratory pump is inadequate and cannot maintain ventilation to eliminate CO2 produced by metabolism

Question 4

Define the following types of RF:

1. Acute
2. Chronic
3. Acute on Chronic

Answer 4

Acute
- rapid, short course, pronounced symptoms

Chronic
- long duration with poor ABGs, has metabolic compensation

Acute on Chronic
- acute exacerbation of chronic COPD

Question 5

Mechanisms of Hypoxaemic RF

Answer 5

1. REDUCED going to areas with perfusion (LLV)
2. NO GAS going to areas with perfusion (atelectasis)
3. Diffusion impairment (pulmonary fibrosis)
4. Gas going to area with reduced perfusion (PE)

Question 6

Mechanisms of Hypercapnic RF

Answer 6

Impairment of the PUMP

• reduced drive (opiate overdose, brainstem injury)
• impairment neuromuscular function (eg. cord injury, myopathy, respiratory fatigue)*

*i.e issues wth spinal cord, motor units, mm tissue itself

Impairment of the LOAD

• increased airway resistance
• reduced chest wall compliance (kyphoscoliosis)
• reduced lung compliance (collapse)

Question 7

Hypoxaemia - S/Sx

Answer 7

1. Reduced mental acuity (if PaO2 < 40-50 mmHg)
2. Agitation -> somnolence
3. Dyspnoea
4. Increased RR
5. Organ failure

Question 8

Hypercapnia - S/Sx

Answer 8

*depends on rate of CO2 rise and amount of compensation!

1. Dyspnoea
2. Increased RR
3. Agitation/Confusion
4. Coma
5. Increased ICP, HA

Question 9

What are the reasons for intubation?

Answer 9

1. Keep the airway open (things like swelling can close off the airway)
2. Protect LRT
3. Allows to clean out excessive secretions (adequate trachiobronchial toilet)
4. Ventilatory support (mechanical ventilation during paralysis/sedation; O2 therapy - CPAP/PEEP)

Question 10

What is minute ventilation and how to calculate?

Answer 10

• amount of gas going into lungs/min

- Ve x RR

Question 11

What is dead space ventilation and how to calculate?

Answer 11

• the amount of gas not participating in gas exchange

- Vd x RR

Question 12

What is alveoloar ventilation and how to calculate?

Answer 12

• the amount of air reaching the alveoli for gas exchange
• Ve - Vd = Va
• MINUTE VENTILATION - DEADSPACE VENTIALTION = ALVEOLAR VENTILATION