Pulmonary edema

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Pulmonary edema
Other namesPulmonary oedema
Pulmonary edema with small pleural effusions on both sides
SpecialtyCardiology, critical care medicine

Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs.[1] It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due to either failure of the left ventricle of the heart to remove oxygenated blood adequately from the pulmonary circulation (cardiogenic pulmonary edema), or an injury to the lung tissue directly or blood vessels of the lung (non-cardiogenic pulmonary edema).[2]

Treatment is focused on three aspects: firstly improving respiratory function, secondly, treating the underlying cause, and thirdly preventing further damage and assuring full recovery to the lung. Pulmonary edema, especially when sudden (acute), can lead to respiratory failure or cardiac arrest due to hypoxia. It is a cardinal feature of congestive heart failure. The term edema is from the Greek οἴδημα (oidēma, "swelling"), from οἰδέω (oidéō, "(I) swell").[3][4]


Classically it is cardiogenic (left ventricular) but fluid may also accumulate due to damage to the lung. This damage may be from direct external injuries or injuries mediated by high pressures within the pulmonary circulation. When directly or indirectly caused by increased left ventricular pressure, pulmonary edema may form when mean pulmonary pressure rises from the normal average of 15 mmHg[5] to above 25 mmHg, where pulmonary fluid may form.[6] Broadly, the causes of pulmonary edema can be divided into cardiogenic and non-cardiogenic. By convention, cardiogenic specifically refers to left ventricular causes.


  • Congestive heart failure which is due to the heart's inability to pump the blood out of the pulmonary circulation at a sufficient rate resulting in elevation in pulmonary wedge pressure and edema – this usually is due to left ventricular failure, but may also be from arrhythmias, or fluid overload, (e.g. from kidney failure or intravenous therapy).
  • Hypertensive crisis can cause pulmonary edema as the elevation in blood pressure and increased afterload on the left ventricle hinders forward flow in blood vessels and causes the elevation in wedge pressure and subsequent pulmonary edema.


  • Negative pressure pulmonary edema[7] in which a significant negative (internal) pressure in the chest (such as from an inhalation against an upper airway obstruction) ruptures capillaries and floods the alveoli with blood. Negative pressure pulmonary edema has an incidence in the range of 0.05-0.1% in cases of general anesthesia. The negative pressure causes a significant increase in preload, thereby increasing pulmonary blood volume.  There is also a significant increase in left ventricular afterload, which causes a decreased cardiac output.  The increase in pulmonary blood volume and pressure along with a decrease in cardiac output to the lungs will increase the pulmonary transudative pressures and the risk of pulmonary edema. With all this occurring, pulmonary vascular resistance increases causing a shift of the intraventricular septum.  The ventricular septal shift to the left causes a left ventricular diastolic dysfunction, which further increases pulmonary hydrostatic pressures and the risk.[8]
  • Neurogenic causes[9] (seizures, head trauma, strangulation, electrocution).
  • Pulmonary embolism[10]

Acute lung injury may also cause pulmonary edema directly through injury to the vasculature and parenchyma of the lung. It includes acute lung injury and acute respiratory distress syndrome.[11] (ALI-ARDS) cover many of these causes, but they may also include:

Some causes of pulmonary edema are less well characterised and arguably represent specific instances of the broader classifications above.

Signs and symptoms[edit]

The most common symptom of pulmonary edema is difficulty breathing (dyspnea), but may include other symptoms such as coughing up blood (classically seen as pink or red, frothy sputum), excessive sweating, anxiety, and pale skin. Shortness of breath can manifest as orthopnea (inability to breath sufficiently when lying down flat due to breathlessness) and/or paroxysmal nocturnal dyspnea (episodes of severe sudden breathlessness at night). These are common presenting symptoms of chronic and cardiogenic pulmonary edema due to left ventricular failure. The development of pulmonary edema may be associated with symptoms and signs of "fluid overload" in the lungs; this is a non-specific term to describe the manifestations of right ventricular failure on the rest of the body and includes peripheral edema (swelling of the legs, in general, of the "pitting" variety, wherein the skin is slow to return to normal when pressed upon due to fluid), raised jugular venous pressure and hepatomegaly, where the liver is excessively enlarged and may be tender or even pulsatile. Other signs include end-inspiratory crackles (crackling sounds heard at the end of a deep breath) on auscultation and the presence of a third heart sound.[2]

Flash pulmonary edema[edit]

Flash pulmonary edema (FPE) is rapid onset acute pulmonary edema. It is most often precipitated by acute myocardial infarction or mitral regurgitation, but can be also caused by aortic regurgitation, heart failure, or almost any cause leading to elevated left ventricular filling pressures. Treatment of FPE should be directed at the underlying cause, but the mainstays are nitroglycerin, ensuring adequate oxygenation with non-invasive ventilation, and decrease of pulmonary circulation pressures while FPE stays.[20]

Recurrence of FPE is thought to be associated with hypertension[21] and may signify renal artery stenosis.[22] Prevention of recurrence is based on managing or preventing hypertension, coronary artery disease, renovascular hypertension, and heart failure.


X-Ray showing pulmonary edema
Pulmonary edema on CT-scan (coronal MPR)

There is no single test for confirming that breathlessness is caused by pulmonary edema – there are many causes of shortness of breath; but there are methods to suggest a high probability of an edema.

Low oxygen saturation in blood and disturbed arterial blood gas readings support the proposed diagnosis by suggesting a pulmonary shunt. A chest X-ray will show fluid in the alveolar walls, Kerley B lines, increased vascular shadowing in a classical batwing peri-hilum pattern, upper lobe diversion (biased blood flow to the superior parts instead of inferior parts of the lung), and possibly pleural effusions. In contrast, patchy alveolar infiltrates are more typically associated with noncardiogenic edema[2]

Lung ultrasounds, employed by a healthcare provider at the point of care, is also a useful tool to diagnose pulmonary edema; not only is it accurate, but it may quantify the degree of lung water, track changes over time, and differentiate between cardiogenic and non-cardiogenic edema.[23]

Especially in the case of cardiogenic pulmonary edema, urgent echocardiography may strengthen the diagnosis by demonstrating impaired left ventricular function, high central venous pressures and high pulmonary artery pressures leading to pulmonary edema.

Blood tests are 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 also typically requested as further diagnosis. B-type natriuretic peptide (BNP) is available in many hospitals, sometimes even as a point-of-care test. Low levels of BNP (<100 pg/ml) suggest a cardiac cause is unlikely.[2]


In those with underlying heart or lung disease, effective control of congestive and respiratory symptoms helps prevents pulmonary edema.[24]

Dexamethasone is in widespread use for the prevention of high altitude pulmonary edema. Sildenafil is used as a preventive treatment for altitude-induced pulmonary edema and pulmonary hypertension,[25][26] the mechanism of action is via phosphodiesterase inhibition which raises cGMP, resulting in pulmonary arterial vasodilation and inhibition of smooth muscle cell proliferation and indirectly fluid formation in the lungs.[27] While this effect has only recently been discovered, sildenafil is already becoming an accepted treatment for this condition, in particular in situations where the standard treatment of rapid descent (acclimatization) has been delayed for some reason.[28]


The initial management of pulmonary edema, irrespective of the type or cause, is supporting vital functions while edema lasts. Therefore, if the level of consciousness is decreased it may be required to proceed to tracheal intubation and mechanical ventilation to prevent airway compromise. Hypoxia (abnormally low oxygen levels) may require supplementary oxygen to balance blood oxygen levels, but if this is insufficient then again mechanical ventilation may be required to prevent complications caused by hypoxia.[29] Treatment of the underlying cause is the next priority; pulmonary edema secondary to infection, for instance, would require the administration of appropriate antibiotics or antivirals.[30]

Cardiogenic pulmonary edema[edit]

Acute cardiogenic pulmonary edema often responds rapidly to medical treatment.[31] Positioning upright may relieve symptoms. A loop diuretic such as furosemide (or Lasix®) is administered, often together with morphine to reduce respiratory distress.[31] Both diuretic and morphine may have vasodilator effects, but specific vasodilators may be used (particularly intravenous glyceryl trinitrate or ISDN) provided the blood pressure is adequate.[31]

Continuous positive airway pressure and bilevel positive airway pressure (CPAP/BiPAP) has been demonstrated to reduce mortality and the need of mechanical ventilation in people with severe cardiogenic pulmonary edema.[32]

It is possible for cardiogenic pulmonary edema to occur together with cardiogenic shock, in which the cardiac output is insufficient to sustain an adequate blood pressure to the lungs. This can be treated with inotropic agents or by intra-aortic balloon pump, but this is regarded as temporary treatment while the underlying cause is addressed and the lungs recover.[31]


  1. ^ Dorland's illustrated medical dictionary (32nd ed.). Saunders/Elsevier. p. 593. ISBN 9781416062578.
  2. ^ a b c d Ware LB, Matthay MA (December 2005). "Clinical practice. Acute pulmonary edema". N. Engl. J. Med. 353 (26): 2788–96. doi:10.1056/NEJMcp052699. PMID 16382065.
  3. ^ οἴδημα, οἰδέω. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  4. ^ Harper, Douglas. "edema". Online Etymology Dictionary.
  5. ^ What Is Pulmonary Hypertension? From Diseases and Conditions Index (DCI). National Heart, Lung, and Blood Institute. Last updated September 2008. Retrieved on 6 April 2009.
  6. ^ Adair, Olivia Vynn (2001). Cardiology secrets (2nd ed.). Elsevier Health Sciences. Chapter 41, page 210. ISBN 1-56053-420-6.
  7. ^ Papaioannou V, Terzi I, Dragoumanis C, Pneumatikos I (2009). "Negative-pressure acute tracheobronchial hemorrhage and pulmonary edema". J Anesth. 23 (3): 417–20. doi:10.1007/s00540-009-0757-0. PMID 19685125. S2CID 9616605.
  8. ^ Hines, Roberta L. and Marschall, Katherine. Stoelting's Anesthesia and Co-Existing Disease. 6th edition. 2012. pages 178 and 179.
  9. ^ O'Leary, R.; McKinlay, J. (2011). "Neurogenic pulmonary oedema". Continuing Education in Anaesthesia, Critical Care & Pain. 11 (3): 87–92. doi:10.1093/bjaceaccp/mkr006. S2CID 18066655.
  10. ^ "Pulmonary edema". Mayo Clinic. 2018-08-08.
  11. ^ Boyle, AJ; Mac Sweeney, R; McAuley, DF (August 2013). "Pharmacological treatments in ARDS; a state-of-the-art update". BMC Med. 11: 166. doi:10.1186/1741-7015-11-166. PMC 3765621. PMID 23957905.
  12. ^ Hampson NB, Dunford RG (1997). "Pulmonary edema of scuba divers". Undersea Hyperb Med. 24 (1): 29–33. PMID 9068153. Archived from the original on 2010-06-17. Retrieved 2008-09-04.{{cite journal}}: CS1 maint: unfit URL (link)
  13. ^ Cochard G, Arvieux J, Lacour JM, Madouas G, Mongredien H, Arvieux CC (2005). "Pulmonary edema in scuba divers: recurrence and fatal outcome". Undersea Hyperb Med. 32 (1): 39–44. PMID 15796313. Archived from the original on September 20, 2008. Retrieved 2008-09-04.{{cite journal}}: CS1 maint: unfit URL (link)
  14. ^ Kumar, Manish; Thompson, Paul D. (2019-04-03). "A literature review of immersion pulmonary edema". The Physician and Sportsmedicine. 47 (2): 148–151. doi:10.1080/00913847.2018.1546104. ISSN 0091-3847. PMID 30403902. S2CID 53209012.
  15. ^ "Adverse Reactions". Professional Education. 2016-06-02. Archived from the original on 2016-12-20. Retrieved 2016-12-03.
  16. ^ "Transfusion-related acute lung injury (TRALI)". Professional Education. 2016-06-17. Retrieved 2016-12-03.
  17. ^ Luks AM (2008). "Do we have a "best practice" for treating high altitude pulmonary edema?". High Alt. Med. Biol. 9 (2): 111–4. doi:10.1089/ham.2008.1017. PMID 18578641.
  18. ^ Bates, M (2007). "High altitude pulmonary edema". Altitude Physiology Expeditions. Retrieved 2008-09-04.
  19. ^ White J, Gray M, Fisher M (1989). Atrax Robustus IPCS InChem
  20. ^ Long, Brit; Koyfman, Alex; Gottlieb, Michael (2018). "Management of Heart Failure in the Emergency Department Setting: An Evidence-Based Review of the Literature". The Journal of Emergency Medicine. 55 (5): 635–646. doi:10.1016/j.jemermed.2018.08.002. PMID 30266198. S2CID 52884356.
  21. ^ Kramer K, Kirkman P, Kitzman D, Little WC (Sep 2000). "Flash pulmonary edema: association with hypertension and recurrence despite coronary revascularization". Am Heart J. 140 (3): 451–5. doi:10.1067/mhj.2000.108828. PMID 10966547.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  22. ^ Pickering TG, Herman L, Devereux RB, Sotelo JE, James GD, Sos TA, Silane MF, Laragh JH (1988). "Recurrent pulmonary oedema in hypertension due to bilateral renal artery stenosis: treatment by angioplasty or surgical revascularisation". Lancet. 332 (8610): 551–2. doi:10.1016/S0140-6736(88)92668-2. PMID 2900930. S2CID 36141498.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  23. ^ Volpicelli, Giovanni; Elbarbary, Mahmoud; Blaivas, Michael; Lichtenstein, Daniel A.; Mathis, Gebhard; Kirkpatrick, Andrew W.; Melniker, Lawrence; Gargani, Luna; Noble, Vicki E. (2012-04-01). "International evidence-based recommendations for point-of-care lung ultrasound". Intensive Care Medicine. 38 (4): 577–591. doi:10.1007/s00134-012-2513-4. ISSN 1432-1238. PMID 22392031.
  24. ^ Light, R. W.; Lee, Y. C. G. (2006-01-01), "PLEURAL EFFUSIONS | Overview", in Laurent, Geoffrey J.; Shapiro, Steven D. (eds.), Encyclopedia of Respiratory Medicine, Oxford: Academic Press, pp. 353–358, doi:10.1016/b0-12-370879-6/00299-4, ISBN 978-0-12-370879-3, retrieved 2020-12-11
  25. ^ Richalet JP, Gratadour P, Robach P, et al. (2005). "Sildenafil inhibits altitude-induced hypoxemia and pulmonary hypertension". Am. J. Respir. Crit. Care Med. 171 (3): 275–81. doi:10.1164/rccm.200406-804OC. PMID 15516532.
  26. ^ Perimenis P (2005). "Sildenafil for the treatment of altitude-induced hypoxaemia". Expert Opin Pharmacother. 6 (5): 835–7. doi:10.1517/14656566.6.5.835. PMID 15934909. S2CID 24900169.
  27. ^ Clark, Michael; Kumar, Parveen J. (2009). Kumar and Clark's clinical medicine. St. Louis, Mo: Elsevier Saunders. p. 783. ISBN 978-0-7020-2993-6.
  28. ^ Fagenholz PJ, Gutman JA, Murray AF, Harris NS (2007). "Treatment of high altitude pulmonary edema at 4240 m in Nepal". High Alt. Med. Biol. 8 (2): 139–46. doi:10.1089/ham.2007.3055. PMID 17584008.
  29. ^ MacIntyre, Neil R (Jan 2013). "Supporting Oxygenation in Acute Respiratory Failure". Respiratory Care. 1 (58): 142–150. doi:10.4187/respcare.02087. PMID 23271824.
  30. ^ "Pulmonary Edema: Symptoms, Causes, and Treatment". Healthline. 13 May 2014. Archived from the original on 28 April 2022.
  31. ^ a b c d Cleland JG, Yassin AS, Khadjooi K (2010). "Acute heart failure: focusing on acute cardiogenic pulmonary oedema". Clin Med. 10 (1): 59–64. doi:10.7861/clinmedicine.10-1-59. PMC 4954483. PMID 20408310.
  32. ^ Wang, Y; Brown, J; Godfrey, C; Ahmad, M; Vital, FMR; Lambiase, P; Banerjee, A; Bakhai, A; Chong, M (2019). "Non‐invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary oedema". Cochrane Database of Systematic Reviews. 2019 (4): CD005351. doi:10.1002/14651858.CD005351.pub4. PMC 6449889. PMID 30950507.