Acute Lung Injury

Blog Post by Andrew Klein, Consultant, Cardiothoracic Anaesthesia and Critical Care, Papworth Hospital, Cambridge, UK

Acute lung injury (ALI) is a relatively common condition with significant morbidity and mortality, despite improvements in management over the last 10 years. It is the subject of a great deal of research and scholarly debate, as many patients are young and prognosis and outcome remains relatively poor.

ALI is also commonly known as Acute Respiratory Distress Syndrome (ARDS). It affects approximately 80 patients per 100,000. Mortality increases with age, from 24% for young patients to 60% for patients 85 years of age or older. In the United States, estimates suggest that there are up to 200,000 cases of acute lung injury per year, which are associated with 74,500 deaths and 3.6 million hospital days.

ALI may follow an acute respiratory infection, or be secondary to another medical condition. Any respiratory infection may trigger the condition, but H1N1 (swine flu) appears to cause a particularly severe form of the disease in patients with underlying medical conditions and during pregnancy. ALI may develop as a complication of blood transfusion, cardiac surgery, major trauma, septicaemia, head injury and a number of other illnesses.

Patients with the disease suffer from hypoxia (low oxygen concentration in the blood) that requires oxygen therapy, and if this is not sufficient may require mechanical ventilation in intensive care. This however is not straightforward because of the damage caused to the lungs by ALI, and may in fact worsen the patients’ condition. On occasion, more advanced ventilatory strategies may be required, such as high frequency oscillation. If the patients’ condition deteriorates further despite best treatment, extra corporeal membrane oxygenation (ECMO) may be attempted as a last ditch therapy. This necessitates transfer to a specialist unit, and may be associated with survival rates of up to 50% in experienced hands, which has improved significantly over the last 5 years. The recent H1N1 outbreak in Australia and New Zealand led to ECMO treatment in over 20 patients, with good results reported.

For more information, please see Core Topics in Cardiothoracic Critical Care, edited by Andrew Klein, Alain Vuylsteke and Samer A. M. Nashef, and published by Cambridge University Press.

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