0910 - Respiratory Failure - RM

Question 1

What tests do you order when diagnosing Dyspnoea?

Answer 1

General observations
Vital Signs
SaO2/Blood Gases
CXR
ECG

Question 2

What is acute respiratory failure? How does it differ from dysponea?

Answer 2

Acute Respiratory Failure exists when the pulmonary system is no longer able to meet the metabolic demands of the body. Dyspnoea is a symptom (though could argue sign) of breathlessness and laboured/difficult breathing.

Question 3

What are the two types of respiratory failure?

Answer 3

Type 1 - Hypoxaemic - PaO2 ≤ 60mmHg on room air

Type 2- Hypercapneic - PaCO2 ≥ 45mmHg - often mildly hypoxic as well.

Question 4

What are the two possible causes of hypoventilation?

Answer 4

Ventilation = TV*RR

Failure of either TV or RR can cause hypoventilation.

Question 5

What are some pathologies that could cause acute respiratory failure?

Answer 5

Type I:
Low FIO2
Deadspace ventilation (e.g. embolism)
Diffusion abnormality (e.g. fibrosis or oedematous heart failure)
Shunting (perfusion without ventilation)

Type 2:
Hypoventilation - Look at the CO

Question 6

What are the clinical signs of respiratory failure?

Answer 6

Signs of compensation (tachypnoea, use of accessories, flaring, intercostal/suprasternal/supraclavicular recession)
Ineffective ventilation (paradoxical breathing)
Increased sympathetic tone (tachycardia, hypertension, sweating)
End-organ hypoxia (altered mental status, later bradycardia and hypotension)
Haemoglobin desaturation (cyanosis)

Question 7

How can you tell between acute and chronic respiratory failure?

Answer 7

Acute has rapid onset and the body does not have an opportunity to compensate. Purely elevated CO2 levels.

Chronic is present for more than 24hrs, and the body can compensate with changed bicarbonate levels:
Increased HCO3- with Type 2
Decreased HCO3- with type 1

Question 8

How do you manage respiratory failure?

Answer 8

Ensure airway patency
Monitor blood gases (PaO2 and PaCO2)
Treat underlying cause of RF
Provide supplemental O2, aiming for 90% (60mmHg) - ideally by NIV if possible

Question 9

What are the contraindications to non-invasive ventilation?

Answer 9

Untreated pneumothorax (displaces mediastinum and causes tension pneumothorax)
Imminent cardiac/respiratory arrest (bigger issue to deal with)
Medically unstable (sepsis/hypotension - do it in ICU)
Decreased consciousness
Vomiting