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# Summary
 
Acute pulmonary oedema refers to fluid accumulation in the interstitium and alveoli of the lungs, which may be cardiogenic or non-cardiogenic. Symptoms include severe dyspnoea, diaphoresis, paroxysmal noctural dyspnoea, orthopnoea and a cough classically productive of pink frothy sputum. Key investigations include a chest X-ray for diagnosis, an ABG, ECG basic bloods including a troponin and BNP and an echocardiogram. Management involves giving oxygen, IV Furosemide and consider non-invasive or invasive ventilation in patients not responding to treatment.
 
# Definition
 
Acute pulmonary oedema is a condition that occurs when excess fluid accumulates in the lungs, particularly within the pulmonary interstitium and alveoli.
 
# Aetiology
 
Pulmonary oedema can be divided into two main groups: cardiogenic and non-cardiogenic.

Cardiogenic pulmonary oedema is associated with raised pulmonary capillary pressures, with the following causes:

- Acute coronary syndrome
- Decompensation of chronic heart failure (e.g. stopping diuretics, infection, volume overload)
- Valvular disorders (e.g. acute mitral regurgitation)
- Acute arrhythmia
- Acute myopathies (e.g. myocarditis, postpartum cardiomyopathy)
- Medications e.g. NSAIDs
- Hypertensive crisis

Non-cardiogenic causes of pulmonary oedema include:

- Acute respiratory distress syndrome
- Renal artery stenosis
- Acute kidney injury
- Iatrogenic fluid overload
- High altitude
- Neurogenic pulmonary oedema (e.g. secondary to head injury)

# Signs and Symptoms
 
**Symptoms include:**

- Severe dyspnoea
- Orthopnoea
- Paroxysmal nocturnal dyspnoea (PND)
- Anxiety
- Diaphoresis
- Cough - may be dry or productive of pink frothy sputum
- Nausea

**On examination, signs include:**

- Respiratory distress
- Tachypnoea
- Tachycardia
- Raised jugular venous pressure (JVP)
- Inspiratory crepitations on auscultation
- Gallop rhythm (3rd heart sound)
- Peripheral oedema and hepatomegaly if secondary to right heart failure
- Hypotension and oliguria if in cardiogenic shock
 

# Differential Diagnosis
 
- **Acute exacerbation of chronic obstructive pulmonary disease**: also associated with dyspnoea and cough, usually productive of sputum and symptoms of orthopnoea and PND not present.
- **Pneumonia**: also causes dyspnoea and cough, patients usually are febrile and may have other symptoms such as chest pain. Can be differentiated on chest X-ray (showing consolidation in pneumonia).
- **Pulmonary embolism**: also causes sudden dyspnoea, may have haemoptysis and tachycardia. Risk factors e.g. immobility may be present, chest X-ray is typically normal but can co-exist with other pulmonary pathologies.

# Investigations

**Bedside tests:**

- **ECG** to look for causes e.g. ischaemic changes in acute coronary syndrome or an arrhythmia, may show evidence of chronic heart failure e.g. left ventricular hypertrophy
- **Arterial blood gas** to assess for respiratory failure which is usually type 1 unless consciousness is impaired in severe illness

**Blood tests:**

- **Full blood count** and **CRP** for inflammatory markers as infection may precipitate acute pulmonary oedema
- **U&Es** and **LFTs** to look for renal or hepatic causes of pulmonary oedema, hyponatraemia may occur
- **Troponin** to investigate for acute coronary syndrome
- **BNP** which should be raised in heart failure

**Imaging:**

- **Chest X-ray** classically shows ABCDE signs of pulmonary oedema:
        - **A**lveolar opacification (bilateral perihilar lung shadowing)
        - Kerley **B** lines (thickened subpleural interlobular septa)
        - **C**ardiomegaly
        - Upper lobe **D**iversion
        - Pleural **E**ffusions
- **Echocardiogram** to assess heart function and look for a cause e.g. valvular disease

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# Management
 
An ABCDE approach should be taken and a medical emergency call put out if required:

- **Airway**
    - Position the patient upright
    - Intubation may be required in some cases e.g. reduced GCS secondary to hypercapnia in patients who have tired
- **Breathing**
    - Give high flow oxygen via a non-rebreather mask
    - Non-invasive ventilation (NIV) may be required e.g. in cases of severe dyspnoea and acidaemia
- **Circulation**
    - Ensure the patient has adequate IV access
    - Give IV furosemide, usually in boluses of 20-40mg
    - Nitrates should not be used routinely
    - Inotropes or vasopressors may be required in cases of cardiogenic shock
    - Monitor input-output and consider a urinary catheter
- **Disability**
     - Small doses of morphine may be required for agitation or chest pain but opiates should not be given routinely
- **Exposure/Everything Else**
     - Review medications - beta-blockers should usually be continued unless the patient is bradycardic or shocked
     - Ensure cardiology are aware in cases of cardiogenic pulmonary oedema
     - Mechanical circulatory support (e.g. a ventricular assist device) is an option in acute severe heart failure 
 
# NICE Guidelines

[NICE - Acute heart failure: diagnosis and management](https://www.nice.org.uk/guidance/cg187/)

# References
 
[Radiopaedia - Pulmonary Oedema](https://radiopaedia.org/articles/pulmonary-oedema-summary?lang=gb)

[Patient UK - Acute Pulmonary Oedema](https://patient.info/doctor/acute-pulmonary-oedema)

[RCEM Learning - Cardiogenic Pulmonary Oedema](https://www.rcemlearning.co.uk/reference/cardiogenic-pulmonary-oedema/)
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Emergency management of acute pulmonary oedema
Topic
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Internal Medicine
# Drug choice feedback

Administration of furosemide, a loop diuretic, is the most appropriate treatment for this gentleman to alleviate his shortness of breath and peripheral oedema. It is an effective and inexpensive choice of diuretic.

# Dose/Route/Frequency/Duration feedback

The correct dose is 20-50mg intravenously for adults. This can be increased in steps of 20mg every 2 hours if further treatment is required. Furosemide can be given orally or intramuscularly as well, although the intravenous route is preferred in hospital due to more rapid onset of action and it is given that a cannula is in situ.
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40 mg
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30 mg
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Case Presentation: A 73-year-old gentleman is brought to the Emergency Department with shortness of breath and ankle swelling. He denies any chest pain.


## PH

Ischaemic heart disease, Type 2 diabetes mellitus, Hyperlipidaemia

## DH

Aspirin 75mg OD PO, Ramipril 5mg OD PO, Metformin 1g BD PO, Empaglifozin 10mg, Bisoprolol 2.5mg PO OD, Atorvastatin 80mg PO OD (NKDA)

## On examination

Appears distressed. CRT 3s, peripheries cool. Cannula in situ. Bilateral peripheral oedema up to the mid-shins. JVP seen just inferior to earlobe.

Temperature 37.3°C, HR 110, RR 18, BP 156/68, O2 93% on 5L oxygen, GCS 14, Weight 79kg

## Investigations

FBC: Hb 152, WCC 5.3, Plts 311

U&Es: Na<sup>+</sup> 141, K<sup>+</sup> 4.2, Cl<sup>-</sup> 102, Ur 10.5, Cr 105, eGFR 64mL/min/1.73m<sup>2</sup>

ECG: NSR and left ventricular strain

CXR: cardiomegaly and interstitial oedema

# Prescribing Request

Write a prescription for one drug that is most appropriate to treat his shortness of breath and peripheral oedema.