ards

Question 1

definition of ARDS

Answer 1

syndrome of acute and persistent lung inflammation with increased vascular permeability

Question 2

what is ARDS characterised by

Answer 2

acute onset

bilateral infiltrates consistent with pul oedema

hypoxaemia: PaO2/FiO2 <= 200 mmHg regardless of the level of positive end-expiratory pressure (PEEP);

no clinical evidence for “ left atrial pressure (pulmonary capillary wedge pressure (PCWP) <=18 mmHg).

ARDS is the severe end of the spectrum of ‘acute lung injury’ (ALI).

Question 3

aetiology of ARDS

Answer 3

severe insult to lungs/other organs = release inflamm mediators = increased capilliary perm, pul oedema, impaired gas exchange and reduced compliance

Question 4

RF of ARDS

Answer 4

sepsis

aspiration

pneumonia

pancreatitis

trauma/burns/head injury

transfusion (massive, transfusion-related lung injury)

transplantation (bone marrow/lung)

drug OD/reaction - aspirin/heroin/paraquat

vasculitis

contusion

malaria

head injury

fat embolism

eclampsia

amniotic fluid embolus

hypovolaemic shock

diabetic ketoacidosis

pregnancy

pulonary contusion

smoking inhalation

near drowning

DIC

raised ICP

fat embolus

heart/lung bypass

tumour lysis syndrome

Question 5

stages of ARDS

Answer 5

exudative, proliferative and fibrotic stage.

Question 6

epidemiology of ARDS

Answer 6

Annual UK incidence 1 in 6000

Question 7

sx of ARDS

Answer 7

rapid deteriation of resp func

dyspnoea

resp distress

cough

symptoms of aetiology

Question 8

signs of ARDS

Answer 8

cyanosis

tachypnoea

tachycardia

widespread inspiratory crepitations

hypoxia refractory to oxygen treatment

signs bilateral - may be asymmetrical in early stages

peripheral vasodilation

Question 9

Ix for ARDS

Answer 9

CXR

blood

plasma BNP

echo

pulmonary artery catheterisation

bronchoscopy

Question 10

CXR for ARDS

Answer 10

Bilateral alveolar and interstitial shadowing.

pulmonary infiltrates

Question 11

blood for ARDS

Answer 11

FBC, U&E, LFT, ESR/CRP, amylase, clotting, ABG, blood culture, sputum culture.

Question 12

plasma BNP for ARDS

Answer 12

Plasma BNP < 100 pg/mL may distinguish ARDS/ALI from heart failure,

but higher levels can neither confirm heart failure nor exclude ARDS/ALI in critically ill patients.

Question 13

echo for ARDS

Answer 13

Severe aortic or mitral valve dysfunction or low LVEF suggests haemodynamic oedema over ARDS.

Question 14

pulmonary artery catheterisation fro ARDS

Answer 14

(pulmonary capillary wedge pressure) PCWP <= 18 mmHg

(however high PCWP does not exclude ARDS as patients with ARDS may have concomitant left ventricular dysfunction).

Question 15

bronchoscopy for ARDS

Answer 15

If the cause cannot be determined from the history, and to exclude ddx:

diffuse alveolar haemorrhage,

lavage fluid for microbiology (mycobacteria, Legionella pneumophila, Pneumocystis, respiratory viruses) and cytology (eosinophils, viral inclusion bodies and cancer cells).

Question 16

diagnostic criteria for ARDS

Answer 16

acute onset

CXR - bilateral infiltrates

PCWP<19mmHg or a lack of clinical congestive heart failure.

Refractory hypoxaemia with PaO2: FiO2<200 for ARDS

total thoracic compliance <30mL/cmH2O.

Question 17

mx of ARDS

Answer 17

• managed in ITU
• oxygenation/ventilation to treat the hypoxaemia
• general organ support e.g. vasopressors as needed
• treatment of the underlying cause
• prone positioning and muscle relaxation have been shown to improve outcome in ARDS

Question 18

complications of ARDS

Answer 18