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Query: UMLS:C0034063 (pulmonary edema)
 10,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several mechanisms leading to noncardiac pulmonary edema have been reviewed. Common features are damage to and increased permeability of vascular endothelium, interstitial and alveolar edema fluid high in protein content, increased pulmonary vascular resistance and pressure, nondependent distribution of the edema and normal left atrial or wedge pressure. The available evidence suggests that in some instances the sites of leakage are the pulmonary arterial walls and, perhaps in some, overperfused, damaged capillary beds. Therapeutic obestives differ from those in cardiac pulmonary edema in that efforts are directed toward a reduction in pulmonary blood flow and pulmonary arterial pressure during the period that endothelial healing is taking place.
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PMID:Noncardiac pulmonary edema. 34 43

Understanding of the causes of pulmonary oedema must be based on knowledge of the mechanism responsible for fluid exchange between the several compartments of the normal lung. Recent physiological studies have clarified the main features of these mechanisms. However in three areas knowledge is still incomplete--the magnitude of the hydrostatic and oncotic forces responsible for fluid movement within the lung, the means by which protein leaks across the wall of small pulmonary vessels and the routes by which fluid and protein pass between the interstitial tissues of the lung and the alveolar space. Further work is needed in these areas. On the basis of this physiological knowledge the mode of development of hydrostatic oedema, the role of lymphatics in pulmonary oedema, and the several stages of pulmonary oedema development that may culminate in alveolar flooding are now clearly understood. Knowledge is less complete about oedema due to increased vascular permeability. In some experimental models, such as alloxan, leakage is due to irreversible injury to the alveolar wall; in other models, including ANTU, oedema formation has been shown to depend upon minor and reversible changes in pulmonary vascular endothelium similar to those that cause exudate formation in areas of acute inflammation. In no instance is detailed information available of both the rate and magnitude of protein leakage and of the morphological basis of increased vascular permeability. Further work is required in this area. Present knowledge allows an adequate explanation of the changes that occur in many clinically important types of pulmonary oedema, including cardiac failure and neurogenic pulmonary oedema. Other types of oedema, notably that which may complicate traumatic shock or extrapulmonary sepsis and high altitude pulmonary oedema, are more complex and the details of their pathogenesis are still obscure.
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PMID:Current views on the mechanisms of pulmonary oedema. 36 92

We investigated mechanisms related to the development of acute lung edema, as induced by oleic acid in adult mongrel dogs. The intravenous injection of oleic acid (0.04 ml/kg) was considered to induce a permeability edema, as an enhancement of transvascular protein clearance was observed after the injection. The effects of oleic acid injection on systemic blood pressure (SBP), pulmonary arterial pressure (PAP), pulmonary arterial wedge pressure (PAWP), cardiac output (CO) and airway pressure (AWP) were measured. A significant decrease in CO and increase in AWP were evident after the injection, but there were no changes in SBP, PAP and PAWP. Treatment of the animals with prostaglandin I2 (PGI2) did not alter the induction of edema by oleic acid. However, the decrease in CO and increase in AWP were normalized by treatment with PGI2. Blood platelet count was not affected by oleic acid given in a dose of 0.04 ml/kg. To determine the direct effect of oleic acid on the vascular endothelium, the agent was injected through a catheter placed in the pulmonary artery. Electron microscopic examination revealed severe vacuolation on the endothelium of the pulmonary artery after only 1 min of exposure to oleic acid. Increased permeation of Evans blue into the subendothelial tissue was also observed with oleic acid treatment, compared with findings in the controls. These results indicate that the lung edema induced by oleic acid is due to an increased protein clearance, probably through a direct toxic effect on the vascular endothelium rather than an indirect toxic effect of chemical mediators released from the aggregated platelets.
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PMID:Mechanisms involved in acute lung edema induced in dogs by oleic acid. 351 Aug 75

The lungs are marvelously designed to handle fluid. The mechanical properties of the lungs and the lymphatics act simply and efficiently to drain fluid out of the pulmonary interstitium. Despite the enormous blood flow through the pulmonary and bronchial circulation, a dynamic equilibrium is maintained between fluid fluxing out of the vasculature into the pulmonary interstitium and fluid being drained out of the lungs by the lymphatics. This is obviously important because maintaining "dry" air spaces is essential for normal pulmonary function. Fluid accumulates in the lung when flux across the vascular endothelium exceeds lymphatic drainage. Two different types of abnormalities will result in accumulation of fluid, an increase in pulmonary microvascular pressure and an increase in the pulmonary vascular endothelial permeability to protein. Regardless of the type of abnormality causing pulmonary edema, fluid tends to accumulate in the lungs in a predictable pattern based on the same mechanical properties that normally keep the lung dry. Only by understanding the normal process of fluid handling will the clinician truly appreciate the consequences of pulmonary edema.
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PMID:Pulmonary edema. 351 71

Three South African patients with severe Rickettsia conorii infection had complicated courses of illness with 2 fatal cases and 1 with gangrene of multiple digits. Immunofluorescent organisms of R. conorii were demonstrated in vascular endothelium of brain, leptomeninges, renal glomerular arterioles and capillaries, renal arteries and veins, myocardial capillaries and arteries, pulmonary alveolar capillaries, pancreatic septa, splenic arterioles, and dermis. Rickettsiae were also observed in hepatic sinusoidal lining cells, splenic and lymph node macrophages, and the blood vessels of the partially viable zone of the amputated digits. Pathologic lesions included cerebral and cerebellar perivascular mononuclear leukocytes, mild mononuclear leptomeningitis, glomerular arteriolitis, vascular and perivascular mononuclear cell-rich inflammatory foci in the kidney, pancreas, skin, and myocardium, hepatocellular necrosis, and pulmonary edema. The sites of lesions and rickettsiae showed strong topographical correlation. Thrombi and hemorrhage occurred in a minority of the sites of vascular injury. Rickettsiae were the apparent direct cause of meningoencephalitis, peripheral gangrene, and other foci of vascular injury. Fatal R. conorii infection with disseminated organ involvement emphasizes the pathogenic potential of this disease.
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PMID:Correlation of the distribution of Rickettsia conorii, microscopic lesions, and clinical features in South African tick bite fever. 388 74

Fatty acid embolism of the lung results in pulmonary edema. Isolated lung lobes ventilated and blood perfused at constant pressure were treated with 1 (n = 6) or 45 microliter/kg body wt (n = 6 oleic acid or saline (n = 7). Lobe weight increase linearly over 1-3 h following oleic with regression slopes indicating a more rapid rate of weight gain at the higher oleic acid dosage. Total lobe weight gain was greater in the 45 than in the 1 microliter/kg group (0.60 +/- 0.10 vs. 0.31 +/- 0.07 g/g initial lobe wt) and greater in the acid-treated lobes than in the controls (0.13 +/- 0.05 g/g initial lobe wt). Pulmonary vascular resistance increased 79% after 45 microliter/kg oleic acid but appeared unchanged following 1 microliter/kg oleic acid or saline. The decrease in arterial O2 partial pressure was greater in the 45 microliter/kg group than in the controls, 47 vs 22 Torr. High vascular pressures and increased flow velocities in patent vessels are not essential for oleic acid-associated edema, since weight increased at constant pressure perfusion. Weight gain related to oleic acid dosage suggests that oleic acid increases permeability by affecting the vascular endothelium either directly or through biochemical intermediates endogenous to the lung or blood.
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PMID:Oleic acid dose-related edema in isolated canine lung perfused at constant pressure. 679 Apr 92

Release and metabolism of arachidonic acid are supposed to form the common final pathway of different stimuli on the pulmonary vascular endothelium. In a model of isolated, ventilated and perfused rabbit lungs we investigated the influence of increased availability of free arachidonic acid on pulmonary vascular resistance and permeability. Addition of arachidonic acid to the perfusion fluid or release of arachidonic acid by Ca-ionophore A 23187 regularly produces a characteristic biphasic increase of the pulmonary vascular resistance as well as a continuous increase in permeability, followed by pulmonary edema. Inhibition of cyclooxygenase by indomethacin prevents the augmentation of vascular resistance, the increase of vascular permeability however is enhanced. thus the raise in pulmonary vascular resistance can be ascribed to cyclooxygenase products, the increased pulmonary vascular permeability to lipoxygenase products of arachidonic acid.
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PMID:[Increase of pulmonary vascular resistance and permeability due to the metabolism of free arachidonic acid (author's transl)]. 727 87

The pathogenesis of pulmonary oxygen toxicity is postulated to be related in part to neutrophil-mediated injury. This study examined the effect of a monoclonal antibody directed against the CD11a,b,c/CD18 glycoprotein complex (beta 2 leukocyte integrins) on oxygen-induced lung injury. M8, a monoclonal antibody that binds to the beta chain of the guinea pig leukocyte integrins that facilitate neutrophil adherence to vascular endothelium, was injected into adult guinea pigs prior to and during exposure to > 98% oxygen. Control oxygen-exposed animals were injected with a noninhibitory antibody to the CD18 complex or with saline. Survival in oxygen was similar for animals treated with M8 when compared with those treated with saline (102 versus 105 h, respectively, NS). Pulmonary edema as assessed by protein in the supernatant of bronchoalveolar lavage fluid (BALF) was higher in the three groups of oxygen-exposed animals than in the air-exposed groups (p < 0.01), but it did not differ between the M8 antibody treatment group and the other oxygen-exposed groups. M8 antibody treatment did not decrease hyperoxia-induced neutrophil accumulation into the lung as assessed by myeloperoxidase activity (MPO) in lung homogenates or by neutrophil counts in histologic specimens. M8 antibody also did not decrease neutrophil counts or MPO in alveolar lavage fluid, both of which were significantly elevated in all oxygen-exposed groups. These results suggest that hyperoxia-induced neutrophil migration into the lung and acute lung injury occurs by CD18-independent processes in the guinea pig model of pulmonary oxygen toxicity.
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PMID:Oxygen-induced lung injury in the guinea pig proceeds through CD18-independent mechanisms. 790 67

Recent experimental findings indicate that endotoxin (i.e. lipopolysaccharide) interacts with specific membrane receptors localized to mononuclear phagocytic cells and neutrophils. Binding of endotoxin to these cells, together with endotoxin-induced activation of host vascular endothelium, initiates a series of signal transduction events that culminate in release of numerous biochemical mediators. The latter include cytokines, platelet-activating factor, thromboxane A2, prostaglandins, leukotrienes, nitric oxide, proteases, toxic O2 radicals, and vasoactive amines. These mediators orchestrate complex biological interactions and amplification signals that lead to cardiopulmonary dysfunction and multi-organ failure within 4-6 h of experimental infusion of endotoxin into animals. The pathophysiological changes include decreased cardiac output, systemic hypotension, decreased blood flow and O2 delivery to tissues, intense pulmonary vasoconstriction and hypertension, bronchoconstriction, increased permeability, pulmonary oedema, ventilation-to-perfusion inequalities, hypoxaemia, and haemoconcentration. Metabolic alterations include increased blood lactate and pyruvate, metabolic acidosis, hyperkalaemia and hypoglycaemia. Potential therapeutic modalities for treatment of endotoxaemia/septic shock include specific antagonists directed against lipopolysaccharide, cytokine, and platelet-activating factor receptors, monoclonal antibodies directed against cytokines and lipid A/core polysaccharides of endotoxin, antiproteases, and agents that block release of toxic O2 and arachidonic acid metabolites.
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PMID:Mediators and vascular effects in response to endotoxin. 855 9

Hyperpermeability is the crux of pathogenesis of sudden lung edema in many pulmonary disorders, especially in acute lung injury and acute respiratory distress syndrome (ARDS). Using our modified method for assessment of pulmonary vascular permeability, we observed the effects of xanthine with xanthine oxidase (X-XO) perfused in rat pulmonary artery and the protection of vasoactive intestinal polypeptide (VIP) against the injury of pulmonary vascular permeability. After addition of xanthine oxidase in the perfusate reservoir containing xanthine, 125I-albumin leak index (125I-ALI) was remarkably increased while peak airway pressure (Paw) showed no significant increase, and perfusion pressure of pulmonary artery (Ppa) and lung wet/dry weight ratio (W/D) were only slightly increased. Xanthine plus xanthine oxidase also increased thromboxane B2 (TX B2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in the perfusate. Treatment with VIP obviously reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. The results indicated that VIP has potent protective activity against injury of pulmonary vascular permeability and may be a physiological modulator of inflammatory damage to vascular endothelium associated with toxic oxygen metabolites.
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PMID:[Vasoactive intestinal polypeptide prevents injury of pulmonary vascular permeability due to xanthine with xanthine oxidase]. 857 46


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