Respiratory Failure

Question 1

Define respiratory failure

Answer 1

Syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system

Question 2

Which areas are most affected by respiratory disease?

Answer 2

North America and North Europe

Question 3

What is the biggest risk factor for chronic resp disease in men vs women?

Answer 3

Men = smoking

Women = Household air pollution from sold fuels

Question 4

Why is there limited data on Acute Respiratory Distress Syndrome (ARDS)?

Answer 4

Hetrogenous diseasae presentation

Question 5

What are some of the reasons for ARDS? (5)

Answer 5

Pneumonia
COPD
Infective Exacerbation
Worsening pulmonary hypertension
CF

Question 6

What 2 factors are associated with an increased ARDS mortality?

Answer 6

Advanced age and severity

Question 7

What does the Berlin definition of ARDS classification consider?

Answer 7

Timing - within 1 week of known clinical insult or new or worsening respiratory symptoms

Chest Imaging - bilateral opacities not fully explained by effusion, lobar/lung collapse, nodules

Origin of oedema - resp failure not fully explained by cardiac failure or fluid overload
Need objective assesment to exclude hydrostatic oedema if no risk factor present

Oxygenation - mild -> severe based on PF ratio, when pts on positive end expiratory pressure of 5+

Question 8

What causes acute respiratory failure?

Answer 8

Pulmonary: Infection, aspiration, primary graft dysfunction following lung Tx

Extra-pulmonary: trauma, sepsis, pancreatitis

Neuro-muscular: myasthenic crisis, Guillain-Barre Syndrome (GBS)

Question 9

What causes chronic respiratory failure?

Answer 9

Pulmonary/airways: COPD, CF, lung fibrosis, lobectomy

Musculoskeletal: muscular dystrophy

Question 10

What causes acute on chronic respiratory failure?

Answer 10

Infective exacerbation of chronic diseases -> COPD, CF
Myasthenic crises
Post operative with underlying resp disease

Question 11

Define type I respiratory failure

Answer 11

Hypoxaemic, PaO2 < 60 at sea lvl:
Failure of oxygen exchange
Increased shunt fraction
Due to alveolar flooding
Hypoxaemia refractory to supplemental O2

Question 12

What are some causes of type I resp failure? (6)

Answer 12

Collapse
Aspiration
Fibrosis
Pulmonary hypertension
Pulmonary oedema
Pulmonary embolism

CAFHOE

Question 13

Define type II respiratory failure

Answer 13

Hypercapnic,PaCO2 > 45 at sea lvl:
Failure to exchange or remove CO2
Decreased alveolar minute ventilation (VA)
Dead space ventilation

Question 14

What are some of the causes of type II respiratory failure? (5)

Answer 14

Nervous system
Neuromuscular
Airway obstruction
Muscle failure
Chest wall deformity (e.g. following trauma, ageing)

Question 15

Define type III respiratory failure

Answer 15

Perioperative respiratory failure
Increased atelectasis due to low functional residual capacity
Hypoxaemia or hypercapnoea

Frequently down to abdominal wall mechanics limiting the amount chest can open up

Question 16

How can we prevent type III respiratory failure? (5)

Answer 16

Anaesthetic or operative technique
Incentive spirometry
Good postural positioning during extubation
Make sure muscle relaxant paralysis fully reversed
Analgesia -> stop tensing abdo muscles

-> attempts to lower intra-abdominal pressure

Question 17

Define type IV respiratory failure

Answer 17

Shock - patients who are intubated and ventilated during shock

Poor perfusion of the lung - vasoplegic presentation -> pooling of blood -> reduced central return

Question 18

What are the ventilatory effects on the right and left heart?

Answer 18

Reduced afterload - good for LV, stress across heart muscle reduced

Increased pre-load - bad for RV, increased thoracic pressure affects contractility

Question 19

How do you treat type IV respiratory failure?

Answer 19

Optimise ventilation to improve gas exchange and to unload the respiratory muscles
-> lowering oxygen consumption

Question 20

What are the chronic risk factors for resp failure? (6)

Answer 20

COPD
Pollution
Recurrent pneumonia
CF
Pulmonary fibrosis
Neuro-muscular diseases

Question 21

What are the acute risk factors of ARDS? (4)

Answer 21

Infection (virus, bacterial, both) -> superinfection with gram positive, toxin producing organisms
Aspiration
Pancreatitis
Transfusion

Question 22

What can people with servere and progressive ARDS present with?

Answer 22

Infection with 2 different types of organisms

Question 23

How can aspiration induce ARDS?

Answer 23

Acid causes trauma-induced inflammatory response

Question 24

What are some common origins of shortness of breath? (5)

Answer 24

Lower respiratory tract infection
Aspiration
Trauma (transfusion)
Pulmonary vascular disease
Extrapulmonary

Question 25

What are the pulmonary vascular causes of shortness of breath? (2)

Answer 25

Pulmonary embolus

Haemoptysis

Question 26

What are the extrapulmonary causes of shortness of breath? (2)

Answer 26

Pancreatitis

New medication

Question 27

What are the pulmonary causes of ARDS? (6)

Answer 27

Aspiration
Trauma
Burns: inhalation
Surgery
Drug toxicity
Infection

Question 28

What are the extra-pulmonary causes of ARDS? (8)

Answer 28

Trauma
Pancreatitis
Burns
Transfusion
Surgery
BM transplant
Drug toxicity
Infection

Question 29

What type of cells can you find within the alveolum?

Answer 29

Resident alveolar macrophages

Type II pneumocytes which differentiate into type I