Respiratory failure

Question 1

What is respiratory failure

Answer 1

Acute impairment in gas exchange between the lungs and blood, causing hypoxia +/- hypercapnia

Question 2

What is difference between type 1 and 2 respiratory failure

Answer 2

1 = hypoxia O2 <8/10 and CO2 <6.5
2 = hypoxia with CO2 > 6.5

Question 3

What are causes of type 1 respiratory failure

Answer 3

Pneumonia
pulmonary oedema
PE
asthma
empyshema
pulmonary fibrosis
ARDS

VQ mismatch, hypoventilation, R-L shunts all cause low O2 and high CO2, but CO2 rise triggers increase in ventilation to normalise CO2

Question 4

What are causes of type 2 respiratory failure

Answer 4

Asthma and COPD
reduced respiratory drive e.g. opiates
neuromuscular disease

Alveolar hypoventilation means you can’t get rid of the CO2

Question 5

What are Sx of respiratory failure?

Answer 5

Of underlying disease

Hypoxia: SOB, agitation, confused, cyanosis, polycythaemia, pulmonary hypertension

Hypercapnia: headache, vasodilation, tachycardia, bounding pulse, tremor or flap, drowsiness/coma if severe

Question 6

What are risk factors for respiratory failure

Answer 6

Smoking, respiratory disease, HF, hypercoagulable state

Question 7

What Ix in respiratory failure?

Answer 7

O2 sats: low
ABG

Bloods: ?infection +CXR) ?PE (+ECG and D dimer, CTPA)

Pulmonary function tests e.g. peak flow

Question 8

What are differentials of respiratory failure?

Answer 8

Metabolic cause e.g. DKA
Anxiety attack
Sleep apnoea
Obesity