ARDS + Respiratory Failure

Question 1

What is adult respiratory distress syndrome

Answer 1

Fluid accumulation in alveoli due to increased permeability caused by inflammation
Non cardiac pulmonary oedema

Question 2

What are pulmonary causes of adult respiratory distress

Answer 2

Pneumonia
Direct lung injury 
Smoke inhalation
Vasculitis
Aspiration

Question 3

What are other causes of RDS

Answer 3

Sepsis
Shock
Massive haemorrhage
Blood transfusion - within 6 hours usually known as TRALI
Trauma
Head injury = sympathetic = pulmonary hypertension
DIC
Pancreatitis
Ovarain hyperstimulation 
Liver failure
Bypass
Drugs / toxins

Question 4

What are symptoms of RDS

Answer 4

Acute + severe
SOB
Tachycardia
Tachypnoea
Cyanosis
Bilateral crackles - fine
Low sats
Hyperaemia
Type 1 resp failure as gas exchangedoesnt occur in inflamed lung 
CO2 normal as can compensate by tachypnoea 
Multi-organ failure
Signs of hypercapnia if rises

Question 5

What are symptoms if on ventilatory

Answer 5

Rising ventilatory pressure

Normal capillary wedge pressure excludes cardiac cause

Question 6

What is the criteria for diagnosing RDS

Answer 6

Within 1 week of trigger
Pulmonary oedema on CXR (not explained by collapse or effusion)
Non-cardiogenic cause
PaO2 <40kPa

Question 7

How do you treat RDS

Answer 7

ITU
Oxygen
Negative fluid balance - diuretic / haemodialysis 
Ventilation - low TV 
CPAP but most need ventilation
Organ support 
Vasopressor to maintain CO 
Nutrition
Treat cause

Question 8

What are complications of RDS

Answer 8

Scarring

Decreased lung function

Question 9

What causes atelectasis (collapse)

Answer 9

Post-op

Obstructed airway - COPD / asthma

Question 10

When should you consider atelectasis post op

Answer 10

72 hours

Question 11

What are the symptoms

Answer 11

SOB
Hypoxaemia
Resp difficulty 
Decreased expansion
Decreased breath sounds
NO FEVER - more likely infection

Question 12

How do you treat

Answer 12

Chest physio

Question 13

What is type 1 respiratory failure

Answer 13

PaO2 <8

PaCo2 normal

Question 14

What causes type 1 respiratory failure

Answer 14

V/Q mismatch
Abnormal diffusion
R-L shunt
Hypoventilation = type 2

Question 15

What can cause a V/Q mismatch (poor perfusion due to barrier to gas exchange)

Answer 15

Pneumonia
Pulmonary oedema
PE
Asthma
Emphysema
RDS

Question 16

What are the symptoms of type 1

Answer 16

Features of cause 
Features of hypoxia
Restless
SOB
Agitated
Confusion
Cyanosis

Question 17

What happens in long standing type 1

Answer 17

Polycythaemia
Pulmonary hypertension
Cor pulmonale

Question 18

How do you Dx respiratory failure

Answer 18

FBC, U+E, CRP
ABG
CXR
PFT 
Sputum and blood 
Spirometry - restrictive

Question 19

How do you treat type 1

Answer 19

Treat cause 
Oxygen 
Monitor O2 with ABG and increase if CO2 stable
Assisted ventilation if PaO2 <8
CPAP

Question 20

Why do you want to control O2 delivery even in type 1

Answer 20

As want to be able to see if condition worsens and sats drop

Question 21

Why is CPAP only indicated in type 1

Answer 21

Decreases ventilation as no pressure differenece
Can’t be used in type 2 which is due to decreased ventilation
Useful for pulmonary oedema as pushes fluid out

Question 22

What does CPAP do

Answer 22

Stops lungs collapsing as keeps alveoli open so increases O2 delivery
Can be delivered through high flow nasal cannula - 40l

Question 23

What is O2 a good marker of

Answer 23

Diffusion i.e. in oedema / infection

Question 24

What is CO2 a good marker of

Answer 24

Poor ventilation

Very soluble so shouldn’t be affected by diffusion issues

Question 25

What is type 2 resp failure

Answer 25

PaO2 <8 | PaCO2 >6

Question 26

What causes type 2 respiratory failure

Answer 26

``` Alveolar hypoventilation with or without V/Q mismatch Ventilation issue Asthma COPD OSA Fibrosis Drugs CNS tumour Trauma Neuromuscular Thoracic wall disease ```

Question 27

How does type 2 present

Answer 27

``` Hypercapnia Headache Peripheral vasodilation Tachycardia Bounding pulse Tremor Papilloedema Confusion Drowsy Coma ```

Question 28

How do you treat type 2

Answer 28

``` Treat underlying cause Beware of hypoxic drive Controlled O2 Check ABG regularly Consider NIPPV if CO2 rising Bipap (2 diff pressures) Intubation if this fails ECMO ```

Question 29

Consequences

Answer 29

Acidosis

Question 30

Indications for non-invasive ventilation

Answer 30

COPD with pH 7.25-7.35 Type 2 res failure Cardiopulmonary oedema resistant to CPAP Weaning from tracheostomy

Question 31

What excludes cardiac cause for ARDS

Answer 31

Normal capillary wedge pressure

Question 32

When is ventilation indicated

Answer 32

pH <7.25

Question 33

What is CPAP

Answer 33

Continuous +Ve airway pressure | Keeps airway expanded so air can move in and out

Question 34

What are indications for CPAP

Answer 34

Type 1 resp failure OSA CCF Acute pulmonary oedema as push fluid out

Question 35

What is BiPAP

Answer 35

``` Bilevel +Ve airway pressure Involves high or low pressures to correspond to ventilation Can give - Nasal - Full face mask - Hood ```

Question 36

When is it used

Answer 36

Type 2 resp failure Usually due to COPD If pH <7.35 despite medical therapy

Question 37

What should you always do if on NIV

Answer 37

ABG

Question 38

What causes obstructive pattern on PFT

Answer 38

COPD Asthma Bronchiectasis Bronchiolitis obliterans

Question 39

What is an obstructive pattern

Answer 39

``` FEV1 = significantly reduced FVC = reduced or normal RAtio = reduced ```

Question 40

What causes restrictive pattern on PFT

Answer 40

``` Pulmonary fibrosis Asbestosis Sarcoidosis ARDS Infant respiratory distress Kyphoscoliosis e.g. AS Neuromuscular Severe obesity ```

Question 41

What is a restrictive pattern

Answer 41

``` FEV1 = reduced FVC = significantly reduce Ratio= normal or increased ```

Question 42

ABG

Answer 42

OK

Question 43

What suggests chronic resp acidosis e.g. due to COPD

Answer 43

Elevated bicarb (as compensating)