Respiratory failure

Question 1

What is acute respiratory failure?

Answer 1

Acute impairment in gas exchange between lungs + blood causing hypoxia with or w/o hypercapnia

Question 2

What defines Type 1 respiratory failure?

Answer 2

Hypoxaemia (+ normocapnia)
PaO2 <8 kPa

Question 3

What defines Type 2 respiratory failure?

Answer 3

Hypercapnoea + Hypoxaemia
PaCO2 >6.5 kPa
PaO2 <8 kPa

Question 4

Broadly, what causes respiratory failure?

Answer 4

Impaired gas exchange, decreased ventilation, or both

Question 5

Describe pathophysiology of type 1 respiratory failure

Answer 5

Damage to lung tissue prevents adequate oxygenation of the blood (hypoxaemia)
However, the remaining normal lung is still sufficient to excrete CO2 produced by tissue metabolism. (Less functioning lung tissue is required for CO2 excretion than is needed for oxygenation of blood)

Question 6

Describe pathophysiology of type 2 respiratory failure

Answer 6

Alveolar ventilation insufficient to excrete CO2 being produced.

Due to reduced ventilatory effort, or inability to overcome increased resistance to ventilation – it affects the lung as a whole, + thus CO2 accumulates.

Question 7

Describe development of hypoxaemia in acute and chronic respiratory failure

Answer 7

Acute: occurs over a period of hours to days (<7 days)
Chronic: occurs over a period of weeks to months (>7 days)

Question 8

List 6 causes of type 1 respiratory failure

Answer 8

Pneumonia
Pulmonary oedema
PE
Pulmonary fibrosis
ARDS
High altitude

Question 9

List 4 causes of type 2 respiratory failure

Answer 9

Acute exacerbation COPD/ asthma
CNS depression e.g. opioid OD, stroke, TBI
Resp muscle weakness: MG, GBS, ALS
Decreased chest wall compliance: rib fracture

Question 10

What is the most common cause of type 2 respiratory failure?

Answer 10

COPD

Question 11

List 3 systemic causes of Respiratory failure and how this arises

Answer 11

Severe sepsis, Cardiogenic Shock, Multiorgan dysfunction
Increased O2 consumption +/ or CO2 production

Question 12

List 5 clinical features of hypoxaemia in respiratory failure

Answer 12

Resp: Tachypnea, Dyspnea
Cyanosis
Pleuritic chest pain
Cardiac: Tachycardia, arrhythmia
Altered mental status: e.g., confusion, somnolence, agitation

Question 13

List 8 clinical features of hypercapnia in respiratory failure

Answer 13

Hypopnea
Headache, daytime sleepiness
Anxiety
Warm extremities
Papilledema
Asterixis
Coma
Paralytic ileus

Question 14

List 6 signs of imminent/ ongoing respiratory arrest

Answer 14

Gasping
Inspiratory stridor
Decreased RR
Cyanosis
Absent chest rise
Acute O2 desaturation

Question 15

List 6 possible signs of underlying causes in respiratory failure

Answer 15

Fever: sepsis, pneumonia
Cough: pneumonia, COPD
Chest pain: pneumonia, PE
Signs of general muscle weakness: MG, GBS, myopathies, ALS
Pain on inspiration: rib fracture
CNS depression: opioid use

Question 16

Describe immediate management of respiratory failure

Answer 16

ABCDE approach inc. IV access, pulse oximetry + cardiac monitoring.
Resp support tailored to underlying cause + severity of respiratory failure
Identify + treat rapidly reversible causes
Obtain initial Ix: ABG, routine laboratory studies, ECG, CXR, POCUS

Question 17

What can be used to treat opioid induced respiratory failure?

Answer 17

Naloxone

Question 18

List 2 complications of respiratory failure management

Answer 18

Aspiration pneumonia (due to NIV)
Pneumothorax (due to NIV/ intubation)