Acute Pulmonary Oedema

Question 1

What is pulmonary oedema and what are the typical signs and symptoms?

Answer 1

Pulmonary oedema is an increase of fluid in the alveolar wall and subsequently the alveolar spaces.

Typical history will include:
Dysopnea (typically at night)
Orthopnoea
Cough with frothy pink sputum. 
Chyne Stoke respiration in LVF (periods of apnoea followed by hyperventilation.) 

Signs include:

• Tacypnoeic
• Tachycardia with gallop rhythm (s3/s4)
• Potentially raised JVP
• Basal crackles

Question 2

What is the pathophysiology of pulmonary oedema?

Answer 2

Caused by 1 of the following:

• Increased hydrostatic pressure
• Vessel wall damage
• Low plasma protein (therefore blood flows out of the capillaries)

Question 3

What are the causes of pulmonary oedema?

Answer 3

Cardiac causes: increased hydrostatic pressure, due to a pressure back up

• LVF
• Failure of prosthetic valve
• Ventricular septal defect
• Cardiomyopathy
• Arrhythmias

Non cardiac causes

1. Increased hydrostatic pressure:
   IV fluid overload

2. Increased vessel permeability:
ARDS (adult respiratory distress syndrome)
DIC
Renal failure
Septicaemia
Toxins (Cl, mustard gas)

3. Low plasma proteins:
   Hypoalbuminaemia: liver failure, nephrotic syndrome.

Other causes:
High altitude*
Neurogenic pulmonary oedema
Immersion pulmonary oedema

Question 4

Describe the pathophysiology of pulmonary oedema related to altitude?

Answer 4

Due to 2 reasons:

• Increased pulmonary arterial and capillary pressures (pulmonary hypertension) secondary to hypoxic pulmonary vasoconstriction.
• An idiopathic non-inflammatory increase in the permeability of the vascular endothelium.

Question 5

What are the differential diagnoses of someone with pulmonary oedema?

Answer 5

LVF
Pneumonia
ARDS
PE (young breathless always check)

Question 6

What investigations would you do and what might you see?

Answer 6

CXR:
Bat wing shadowing/haziness.
Pleural effusion/loss of cardiophrenic margin?
Cardiomegaly?

ABG:
Drop in pO2
Drop in pCO2 (due to hyperventilation)
Eventually increase in pCO2 due to impaired has exchange.

ECG/Troponin:
Signs of ischaemia/MI
Tachycardia
Arrhythmias

Echocardiography:
Ejection fraction reduced in heart failure
Valvular heart diseases such as mitral regurgitation.

Question 7

What is the management of pulmonary oedema?

Answer 7

1. Sit the patient up to avoid pulmonary congestion.
2. Give oxygen high flow.
3. Loop diuretics to reduce circulating volume.
4. Fluid restriction

Treat underlying cause:
Infection
Altitude (descend)

For cardiac cause:

Nitrates (vasodilates, reduces bp therefore less afterload on the heart)
Morphine (vasodilates etc).

All patients should be on strict bed rest.