Pulmonary edema

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**Pulmonary edema**
*Classification & external resources*
ICD-10	J 81.
ICD-9	514
DiseasesDB	11017
MedlinePlus	000140
eMedicine	med/1955 radio/581

Pulmonary edema (American English) or oedema (British English) is swelling and/or fluid accumulation in the lungs. It leads to impaired gas exchange and may cause respiratory failure. It is due to either failure of the heart to remove fluid from the lung circulation ("cardiogenic pulmonary edema"), or due to a direct injury to the lung parenchyma ("noncardiogenic pulmonary edema").^[1] Treatment depends on the cause, but focuses on maximizing respiratory function and removing the cause.

1 Signs and symptoms
2 Diagnosis
3 Causes
- 3.1 Cardiogenic
- 3.2 Non-cardiogenic
4 Therapy
5 References
6 See also

[edit] Signs and symptoms

Symptoms of pulmonary edema include difficulty breathing, coughing up blood, excessive sweating, anxiety and pale skin. If left untreated, it can lead to coma and even death, generally due to its main complication of hypoxia.

If pulmonary edema has been developing gradually, symptoms of fluid overload may be elicited. These include nocturia (frequent urination at night), ankle edema (swelling of the legs, generally of the "pitting" variety, where the skin is slow to return to normal when pressed upon), orthopnea (inability to lie down flat due to breathlessness) and paroxysmal nocturnal dyspnea (episodes of severe sudden breathlessness at night).

[edit] Diagnosis

Pulmonary edema is generally suspected due to findings in the medical history, such as previous cardiovascular disease, and physical examination: end-inspiratory crackles (sounds heard at the end of a deep breath) on auscultation (listening to the breathing through a stethoscope) are characteristic for pulmonary edema. The presence of a third heart sound (S3) is predictive of cardiogenic pulmonary edema.^[1]

Blood tests are generally performed for electrolytes (sodium, potassium) and markers of renal function (creatinine, urea). Liver enzymes, inflammatory markers (usually C-reactive protein) and a complete blood count as well as coagulation studies (PT, aPTT) are typically requested. B-type natriuretic peptide (BNP) is available in many hospitals, especially in the US, sometimes even as a point-of-care test. Low levels of BNP (<100 pg/ml) make a cardiac cause very unlikely.^[1]

The diagnosis is confirmed on X-ray of the lungs, which shows increased fluid in the alveolar walls. Kerley B lines, increased vascular filling, pleural effusions, upper lobe diversion (increased blood flow to the higher parts of the lung) may be indicative of cardiogenic pulmonary edema, while patchy alveolar infiltrates with air bronchograms are more indicative of noncardiogenic edema^[1]

Low oxygen saturation and disturbed arterial blood gas readings may strengthen the diagnosis and provide grounds for various forms of treatment. If urgent echocardiography is available, this may strengthen the diagnosis, as well as identify valvular heart disease. In rare occasions, insertion of a Swan-Ganz catheter may be required to distinguish between the two main forms of pulmonary edema.^[1]

[edit] Causes

Pulmonary edema is either due to direct damage to the tissue or as a result of inadequate functioning of the heart or circulatory system.

[edit] Cardiogenic

Congestive heart failure
Severe heart attack with left ventricular failure
Severe arrhythmias (tachycardia/fast heartbeat or bradycardia/slow heartbeat)
Hypertensive crisis
Pericardial effusion with tamponade
Fluid overload, e.g. from kidney failure

[edit] Non-cardiogenic

This form is contiguous with ARDS (acute respiratory distress syndrome):

Inhalation of toxic gases
Multiple blood transfusions
Severe infection
Pulmonary contusion, i.e. high-energy trauma
Multitrauma, e.g. severe car accident
Neurogenic, e.g. subarachnoid hemorrhage
Aspiration, e.g. gastric fluid or in case of drowning
Certain types of medication
Upper airway obstruction
Reexpansion, i.e. post pneumonectomy or large volume thoracentesis
Reperfusion injury, i.e. postpulmonary thromboendartectomy or lung transplantation
Ascent to high altitude occasionally causes high altitude pulmonary edema (HAPE)^[2]

[edit] Therapy

Focus is initially on maintaining adequate oxygenation. This may happen with high-flow oxygen, noninvasive ventilation (either continuous positive airway pressure (CPAP) or variable positive airway pressure (VPAP)^[3]^[4]) or mechanical ventilation in extreme cases.

When circulatory causes have led to pulmonary edema, treatment with intravenous nitrates (glyceryl trinitrate), and loop diuretics, such as furosemide or bumetanide, is the mainstay of therapy. These improve both preload and afterload, and aid in improving cardiac function.

There are no causal therapies for direct tissue damage; removal of the causes (e.g. treating an infection) is the most important measure.

[edit] References

^ ^a ^b ^c ^d ^e Ware LB, Matthay MA. Acute pulmonary edema. N Engl J Med 2005;353:2788-96. PMID 16382065.
^ M Bates. High altitude pulmonary edema. Apex (Altitude Physiology Expeditions). Retrieved on March 6, 2007.
^ Masip J, Roque M, Sanchez B, Fernandez R, Subirana M, Exposito JA. Noninvasive ventilation in acute cardiogenic pulmonary edema: systematic review and meta-analysis. JAMA 2005;294:3124-30. PMID 16380593.
^ Peter JV, Moran JL, Phillips-Hughes J, Graham P, Bersten AD. Effect of non-invasive positive pressure ventilation (NIPPV) on mortality in patients with acute cardiogenic pulmonary oedema: a meta-analysis. Lancet 2006;367(9517):1155-63. PMID 16616558.