ACUTE LUNG INJURY AND ACUTE RESPIRATORY DISTRESS SYNDROME: The Clinical Syndrome
Section snippets
DEFINITIONS
Acute lung injury (ALI) refers to a syndrome of severe, acute respiratory failure characterized by respiratory distress, a severe impairment of oxygenation, and noncardiogenic pulmonary edema. Because ALI, like any other clinical syndrome, can vary in severity, acute respiratory distress syndrome (ARDS) is a term applied to patients with more severe manifestations of ALI. Both terms are used to reflect a relatively specific form of pathologic injury to the lung occurring from a wide range of
INCIDENCE
The incidences of ARDS and ALI are not clear. A National Institutes of Health panel in 1972 estimated the incidence of ARDS to be 150,000 cases a year in the United States, an incidence of approximately 75 cases/100,000 population/year.35 This number has been widely used since that time, without confirmation from epidemiologic studies. Some prospective studies have found a much lower incidence of ARDS, ranging from 1.5 to 8.4 cases/100,000 population/year.5, 6, 7 The methodology to perform an
RISK FACTORS
Clinical risk factors are either conditions associated with ARDS or markers that occur in conditions known to be associated with ARDS. The data on risk factors have been generated primarily for ARDS so this discussion reflects that limitation. These associated conditions can be categorized mechanistically as causing either direct (primary) or indirect (secondary) injury—that is, a result of extrapulmonary illness or injury that injures the lungs through activation of systemic inflammation,
CLINICAL MANIFESTATIONS
ALI and ARDS occur in the setting of acute, severe illness. Clinical manifestations of the patient with ALI or ARDS reflect the underlying illnesses, the severe pulmonary injury, or the multiple organ failure that may co-exist. The clinical manifestations can range widely, depending on the underlying disease process and the number and type of organs that are failing in addition to the lungs. Pulmonary inflammation with alveolar flooding and surfactant depletion result in intrapulmonary
Mortality
Factors associated with mortality include risk factors and age. Sepsis as a risk for ARDS generally is associated with a considerably higher mortality rate than most other common risks, including trauma and aspiration of gastric contents.21 Older patients, often studied as patients greater than 65 years of age, have an increased mortality rate compared with younger patients as determined in several studies.4, 21, 47, 48 None of these studies considered co-morbidities in a multivariant analysis,
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Cited by (50)
Current Knowledge of Acute Lung Injury and Acute Respiratory Distress Syndrome
2012, Critical Care Nursing Clinics of North AmericaCitation Excerpt :Fig. 2 demonstrates current understanding of the complex changes beginning with the proliferative processes and proceeding through resolution of the ALI. Important changes associated with this phase include epithelial repopulation, reabsorption of the alveolar fluid, clearing of the protein residue associated with the influx of the edema fluid observed in the exudative phase of lung injury, and finally resolution of fibrosis.6,7,26,27 The discovery of long-term effects on the pulmonary function of survivors associated with the onset and resolution of ALI has provided additional impetus to the systematic evaluation of quality-of-life (QOL) measures in this population.
Heme oxygenase-1 ameliorates LPS-induced acute lung injury correlated with downregulation of interleukin-33
2011, International ImmunopharmacologyCitation Excerpt :Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is implicated in the development of multisystem organ failure, which plays a critical role in the death of patients with trauma, shock, multiple transfusions and ischemia-reperfusion [1–3].
Pathophysiology of acute respiratory distress syndrome. Glucocorticoid receptor-mediated regulation of inflammation and response to prolonged glucocorticoid treatment
2011, Presse MedicaleCitation Excerpt :Every anatomical component of the pulmonary lobule (epithelium, endothelium and interstitium) is involved including the respiratory bronchioles, alveolar ducts and alveoli, as well as arteries and veins. Diffuse injury to the alveolar-capillary membrane (ACM) causes edema of the airspaces and interstitium with a protein-rich neutrophilic exudate, resulting in severe gas exchange and lung compliance abnormalities [19]. Although the term “syndrome” was applied in its original description, [20] ARDS meets all the constitutive elements of a disease process [21].
Is Acute Lung Injury a Single Syndrome?
2011, Evidence-Based Practice of Critical CareIs Acute Lung Injury a Single Syndrome?
2010, Evidence-Based Practice of Critical Care: Expert Consult: Online and Print
Address reprint requests to Kenneth P. Steinberg, MD, Division of Pulmonary and Critical Care Medicine, Harborview Medical Center, Box 359762, 325 Ninth Avenue, Seattle, WA 98104, e-mail: [email protected]