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PubMed1983

Hemodynamic, biochemical and morphological changes in the dextran and D-galactosamine-induced edemas in rats.

Dextran (600 mg/kg i.p.) and D-galactosamine (300 mg/kg s.c.)-induced edemas in the rat have been evaluated and compared on the basis of hemodynamic, biochemical and morphological investigations. The genesis of the edema induced by dextran was quicker (1-3 hr) than that induced by D-galactosamine. The edema index at the levels of the paws was higher in the dextran (10.5 +/- 0.6) than in the D-galactosamine (5.1 +/- 0.4)-induced edema. Furthermore, the dextran-induced edema was associated with marked hypotension and a decrease in the plasma protein levels. Bradycardia, decrease in the cardiac output and the coronary blood flow were observed in both the edemas. Blood flows to the brain, kidneys, lungs, spleen and paws were decreased only in the dextran-induced edema. It was interesting to note that the percentage distribution of the cardiac output in the paws was decreased in the dextran-induced edema only. PGE2 levels were increased, whereas the histamine levels were decreased in the paw-skin in both the edemas. These changes were relatively more marked in the dextran edema. The levels of PGF2 alpha remained unchanged. The above findings have been further supported by our morphological data where relatively more degranulation of the mast cells and that too at a shorter period, was observed in the dextran-induced edema. Different mechanisms for the genesis of these two kinds of edemas have been suggested.

Animals↗
PubMed1984

Acute pulmonary edema.

Fluid movement from the pulmonary capillaries into the interstitial space occurs continuously and is drained by the lymphatics. With increased leakage or decreased clearance, excessive extravascular lung water accumulates, initially as interstitial edema and subsequently as alveolar edema. The most common cause of pulmonary edema is an increase in microvascular hydrostatic pressure. An increased permeability of the capillaries is the other mechanism of production of pulmonary edema. An acute, critical reduction in colloid osmotic pressure may play a contributory role in pulmonary edema even at normal hydrostatic pressures. Dyspnea, diaphoresis, and anxiety characterize the clinical picture. A history of heart disease and congestive heart failure may be present in CPE, whereas evidence of an inciting event or disease process suggests NCPE. Hypoxia, decreased lung compliance, and increased shunt fraction are seen in both types of pulmonary edema, but the duration of pulmonary edema tends to be more severe and prolonged in NCPE. Evidence of increased permeability in NCPE distinguishes it from CPE. Clinically, this is assumed when pulmonary edema is demonstrated at normal PCWP and when edema fluid protein concentration and COP are close to those of plasma. The management of pulmonary edema consists of the improvement of gas exchange by methods that range from supplemental oxygen administration to mechanical ventilatory support with PEEP, depending on the severity of the disturbance in lung function. Improvement in myocardial function and a decrease in pulmonary congestion are accomplished with diuretics and morphine; in those patients who do not respond to this therapy, manipulation of preload, afterload, and myocardial contractility by vasodilators and inotropic agents may be required. In acute pulmonary edema, intravenously administered agents with a short half-life and rapid onset of action are preferred. The role of colloids in the treatment of pulmonary edema is controversial. The indications for the use of corticosteroids in ARDS are controversial, and an optimum dose has not been determined. Many clinicians tend to choose steroids to treat these patients, but the value of these agents in this setting awaits the results of controlled trials now under way.

Adrenal Cortex Hormones↗
PubMed1993

Cold-induced brain edema in mice. Involvement of extracellular superoxide dismutase and nitric oxide.

The role of extracellular superoxide in the pathogenesis of vasogenic edema was studied using transgenic mice expressing a 5-fold increase in extracellular superoxide dismutase (EC-SOD) activity in their brains. Increased EC-SOD expression offered significant protection against edema development after cold-induced injury (44% less edema than nontransgenic littermates, p < 0.05). Since iron may contribute to vasogenic edema by catalyzing the production of hydroxyl radical from superoxide and hydrogen peroxide, the effects of the chelator deferoxamine were studied. Deferoxamine reduced edema formation after cold-induced injury (43% less edema than controls, p < 0.05); however, treatment with iron-saturated deferoxamine also reduced edema development in mice (32-48% less edema, p < 0.05). This suggested that the protection offered by deferoxamine was independent of its ability to chelate iron. An iron-independent mechanism by which superoxide can contribute to vasogenic edema is via reaction with nitric oxide to produce the potentially toxic peroxynitrite anion, which is also scavenged by deferoxamine. Mice treated with an inhibitor of nitric oxide synthase were protected against cold-induced edema (37% less edema, p < 0.05). EC-SOD transgenic mice received no additional protection by inhibition of nitric oxide synthesis, supporting this novel alternative mechanism of edema formation.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Effect of pulmonary edema on tracheal diameter.

BACKGROUND: Though it is well known that cardiogenic and noncardiogenic pulmonary edema can cause changes in lung mechanics, actual alterations in tracheal diameter have not been described. OBJECTIVE: To evaluate the effects of pulmonary edema induced by increased left atrial pressure (cardiogenic) and Perilla ketone (PK; noncardiogenic) on tracheal diameter in chronically instrumented awake sheep. METHODS: We investigated the effects of two mechanistically distinct types of pulmonary edema on tracheal diameter in chronically instrumented awake sheep. Cardiogenic pulmonary edema (analogous to congestive heart failure in humans) was induced by increasing left atrial pressure ( upward arrowP(LA)) by inflating the balloon on a Foley catheter positioned in the mitral valve annulus to cause partial obstruction to flow across the valve (n = 18). Noncardiogenic pulmonary edema (increased pulmonary microvascular permeability pulmonary edema analogous to the acute respiratory distress syndrome in humans) was produced by the intravenous administration of PK (n = 11). Lateral chest radiographs (CXRs) were scored by a standardized 5-point scoring system for the severity of pulmonary edema, and tracheal diameter was measured at a fixed location in the carina. Three radiologists, blinded to sheep identification number and experimental protocol, evaluated the radiographs independently at different points in time for edema severity and tracheal diameter. The sheep were sacrificed immediately after the final CXR, and wet/dry lung weight ratio (W/D ratio) was determined. RESULTS: Both upward arrowP(LA) and PK were associated with statistically significant tracheal narrowing ( upward arrowP(LA): 20.3 +/- 0.6 to 15.1 +/- 0.9 mm; PK: 20.2 +/- 0.6 to 14.1 +/- 1.4 mm). Tracheal narrowing correlated with the severity of the pulmonary edema determined radiographically ( upward arrowP(LA): r = -0.69, p < 0.01; PK: r = -0.62, p < 0.01) and by W/D ratio ( upward arrowP(LA): r = -0.64, p < 0.05; PK: r = -0.54, p < 0. 05). CONCLUSIONS: We conclude that tracheal narrowing occurs in sheep models of both cardiogenic and noncardiogenic pulmonary edema and that the degree of narrowing correlates with the severity of the edema.

Animals↗
PubMed1996

MIB-1 staining index and peritumoral brain edema of meningiomas.

BACKGROUND: Growth rates and tumor aggressiveness of meningiomas are thought to be closely related to brain edema development. However, histopathologic data alone are not consistently accurate predictors of the behavior and clinical course of a meningioma. METHODS: The authors examined 57 histologically proven intracranial meningiomas to identify factors, including growth fractions determined by MIB-1 immunostaining, that may influence the development of meningioma-associated peritumoral brain edema. There were 54 benign, 2 atypical, and 1 anaplastic meningiomas. The MIB-1 staining index (SI) percentage was defined as the number of MIB-1 positive cells divided by the total number of tumor cells in a 1.037-square millimeter area on the slide. The extent of peritumoral brain edema was determined using preoperative magnetic resonance imaging. The extent of edema was classified as Grade 0,1, or 2 (GR0, GR1, or GR2), in order of increasing severity. RESULTS: The MIB-1 SIs of the 57 cases ranged from 0.06-6.8% (median, 0.80%). There were 26 GR0, 20 GR1, and 11 GR2 edema cases. The MIB-1 SI rose in order of increasing edema severity. There was a statistically significant correlation between the MIB-1 SI and the extent of brain edema (P<0.0001), and also between the tumor size and the extent of brain edema (P=0.001). Meningothelial and atypical/anaplastic meningiomas were associated with peritumoral brain edema more often than any other subtype (P<0.005). CONCLUSIONS: Growth fractions, as determined by MIB-1 immunostaining, rise with increasing severity of peritumoral brain edema, indicating a close relationship between tumor aggressiveness and edema development.

Adult↗
PubMed2004

Pharmacological and histopathological characterization of Bothrops lanceolatus (Fer de lance) venom-induced edema.

OBJECTIVE: Bothrops venoms cause local edema, pain, hemorrhage and necrosis. In this study, we investigated the ability of Bothrops lanceolatus venom to cause edema in rat hind paws and examined the mediators involved. MATERIALS AND METHODS: Hind paw edema was induced in male Wister rats by the subplantar injection of venom (12.5-100 microg/paw) in the absence and presence of antagonists. Edema was quantified by hydroplethysmometry at 0.25, 0.5, 2, 4, 6 and 24 h post-injection and was expressed as the percentage increase relative to the contralateral (control) paw. The ability of the venom to release histamine from rat peritoneal mast cells was also assessed. RESULTS: Venom caused dose- and time-dependent edema that was maximal within 15 min but disappeared after 24 h and was accompanied by hemorrhage. Dexamethasone (1 mg/kg, s.c.), methysergide (6 mg/kg, i.p.), HOE 140 (0.6 mg/kg, i.v.) and mepyramine (6 mg/kg, i.p.) significantly ( p < 0.05) reduced edema formation, whereas indomethacin (10 mg/kg, i.p.) was ineffective. Dialysis did not affect venom-induced edema. Venom (1, 10 and 30 microg/ml) caused a concentration-dependent release of histamine (13 +/- 1%, 61.9 +/- 4.6% and 73.6 +/- 2.4%, respectively; n = 5) from rat peritoneal mast cells in vitro. Histological analysis confirmed the presence of edema, hemorrhage and neutrophil infiltration. Pretreating the venom with EDTA partially inhibited the edema and hemorrhage, but did not affect the migration of neutrophils. CONCLUSIONS: B. lanceolatus venom produced dose- and time-dependent edema in rat paws. This edema was not dependent on low molecular weight substances in the venom, but was partially dependent on a hemorrhagin and also involved the release of arachidonic acid metabolites, bradykinin, histamine and serotonin.

Adrenergic beta-Antagonists↗
PubMed2004

[Optical coherence tomography in the diagnosis and follow-up of patients with uveitic macular edema].

BACKGROUND: Optical coherence tomography (OCT) is a relatively new, noninvasive method and has been well established as an effective diagnostic procedure for the investigation of several macular diseases. Knowledge about the efficacy of OCT in the diagnosis and follow-up of macular edema in uveitis patients is still limited. PATIENTS AND METHODS: In the first part of the study, OCT was performed in 22 eyes of 18 patients with anterior or intermediate uveitis who showed angiographic and fundoscopic evidence of macular edema. The OCT results were compared with the visual acuity and fundoscopic and angiographic appearance of macular edema. In the second part of the study, the same patients were followed over a period of approximately 5 months (+/-2 months) and OCT was repeated at different time points during treatment of uveitic macula edema. RESULTS: OCT investigation also showed clear evidence of macular edema in all eyes and was not compromised by a low or medium degree of optical haze. Furthermore, OCT investigation revealed marked differences in the individual degree of macular edema (foveal heights 168-810 microm). Diffuse macular edema ( n = 4 ) and different types of cystoid macular edema (several distinguished cysts n = 6, partially or completely confluent cysts n = 11, one marked cyst n = 1) were observed. During the follow-up of the patients, OCT results, visual acuity, and fundoscopic appearance of the macula showed a comparable behavior. In some eyes, a stable visual acuity was accompanied by changes of foveal edema demonstrated by OCT. CONCLUSION: Optical coherence tomography is a safe and highly effective method in the diagnosis of macular edema in uveitis associated with low or medium haze of the optical media. Furthermore, OCT investigation seems to be useful in the follow-up of uveitic macular edema under treatment.

Fluorescein Angiography↗
PubMed1981

Ara-C lung: noncardiogenic pulmonary edema complicating cytosine arabinoside therapy of leukemia.

Unexplained fatal pulmonary edema observed at autopsy in leukemic patients treated with cytosine arabinoside (Ara-C) suggested a possible role of the drug in causing increased alveolar capillary permeability. We reviewed clinical and pathologic features of the 181 patients with leukemia who were examined at autopsy at The Johns Hopkins Hospital in the past 12 years, 93 (51 percent) of whom had received intravenous Ara-C in doses of 7.5 to 30 mg/kg/day (average dose, 16 mg/kg/day). Fifty-one patients had received their last treatment within 30 days, and 42 patients between 31 and 894 days, prior to death. Among the 181 patients examined at autopsy 43 (24 percent) had massive edema, 59 (33 percent) had moderate edema, and 79 (44 percent) had either slight edema or no pulmonary edema. The 51 patients who had received Ara-C within 30 days of their death, compared to the other 130, had a highly significant increase in the frequency of pulmonary edema (p less than 0.001), which was massive in 24 and moderate in 18. In these 42 patients, causative or contributing factors that explained the edema were present in 14 (33 percent) of them, but in 28 (67 percent) there was no apparent explanation. In contrast, 60 of the 130 patients who had no or remote Ara-C therapy had massive (19 patients) or moderate (41 patients) pulmonary edema, which was explained in 55 (92 percent) and unexplained in only five (8 percent) (p less than 0.001). The unexplained pulmonary edema, a highly proteinaceous interstitial and intra-alveolar infiltrate, correlated with gastrointestinal lesions typical of Ara-C toxicity (p less than 0.001). Multivariate regression analysis showed that unexplained pulmonary edema was predicted by the recent administration of Ara-C, but by no other chemotherapeutic agent, including daunomycin, a potential cardiotoxin frequently given in conjunction with Ara-C. The study suggests that increased alveolar capillary permeability may result from the intravenous administration of cytosine arabinoside and that this complication should be considered when pulmonary edema develops in leukemic patients treated with Ara-C.

Adolescent↗
PubMed1993

[Therapy of cystoid diffuse macular edema after uveitis and cataract surgery with the carbonic anhydrase inhibitor acetazolamide (Diamox)].

BACKGROUND: Observations made by Cox, Bird et al. (1988), who first used acetazolamide (Diamox) for treatment of macular edema of various origin in a higher number of patients, let assume a positive effect of this therapy on fluid accumulation specifically inside the inner retinal layers. Based on these studies 15 patients (20 eyes) with cystoid or cystoid-diffuse macular edema were treated with acetazolamide in a pilot-study. MATERIALS AND METHODS: Eleven patients (fifteen eyes) had postuveitic macular edema, four other patients (five eyes) had cystoid edema following cataract surgery. Patients with additional diseases causing macular edema of retinal vascular origin were excluded. The initial dose was 500 mg daily. In one patient responding to therapy the dose was gradually reduced after three weeks down to a minimum of 125 mg every second day. For evaluation of the therapeutical results fluorescein angiography and visual acuity were taken into account. RESULTS: Eleven patients (fourteen out of twenty eyes) showed a distinct therapeutical effect with decrease of macular edema in repeatedly controlled fluorescein angiography. All these patients had a subjective improvement of vision which correlated with an increase of visual acuity in exactly one half of all patients. Therapy was stopped, when the macular edema had still appeared unchanged in angiography after three weeks or when--in spite of fluid reduction in angiography--no improvement of visual acuity could be obtained in the next two months. The maintenance dose showed large individual variation with a minimum of 125 mg every second day and a maximum of 250 mg per day. Attempts to stop therapy resulted in a early reappearance of the edema of original extension with corresponding deterioration of visual acuity and sensitivity of central visual field. In a few patients even the reduction of the dose below the individual maintenance dose could be demonstrated angiographically. All patients were under continuous internal medical control, permanent side-effects of acetazolamide with the doses used in this study were not seen. CONCLUSIONS: The results show that acetazolamide is a basically effective agent against cystoid macular edema and that a therapeutical trial is justified based on the treatment criteria of this study. The factors limiting the therapeutical effect of acetazolamide cannot yet be evaluated on the basis of the small amount of patients in this pilot-study. Considering the patient data a time factor depending on the period between onset of edema-related symptoms and begin of treatment is likely. In the group of unsuccessfully treated cases we had the patients with the longest period of preexisting edema (more than one year) of the study.

Acetazolamide↗
PubMed1996

Inhaled nitric oxide for high-altitude pulmonary edema.

BACKGROUND: Pulmonary hypertension is a hallmark of high-altitude pulmonary edema and may contribute to its pathogenesis. When administered by inhalation, nitric oxide, an endothelium-derived relaxing factor, attenuates the pulmonary vasoconstriction produced by short-term hypoxia. METHODS: We studied the effects of inhaled nitric oxide on pulmonary-artery pressure and arterial oxygenation in 18 mountaineers prone to high-altitude pulmonary edema and 18 mountaineers resistant to this condition in a high altitude laboratory (altitude, 4559 m). We also obtained lung-perfusion scans before and during nitric oxide inhalation to gain further insight into the mechanism of action of nitric oxide. RESULTS: In the high-altitude laboratory, subjects prone to high-altitude pulmonary edema had more pronounced pulmonary hypertension and hypoxemia than subjects resistant to high-altitude pulmonary edema. Arterial oxygen saturation was inversely related to the severity of pulmonary hypertension (r=-0.50, P=0.002). In subjects prone to high-altitude pulmonary edema, the inhalation of nitric oxide (40 ppm for 15 minutes) produced a decrease in mean (+/-SD) systolic pulmonary-artery pressure that was three times larger than the decrease in subjects resistant to such edema (25.9+/-8.9 vs. 8.7+/-4.8 mm Hg, P<0.001). Inhaled nitric oxide improved arterial oxygenation in the 10 subjects who had radiographic evidence of pulmonary edema (arterial oxygen saturation increased from 67+/-10 to 73+/-12 percent, P=0.047), whereas it worsened oxygenation in subjects resistant to high-altitude pulmonary edema. The nitric oxide-induced improvement in arterial oxygenation in subjects with high-altitude pulmonary edema was accompanied by a shift in blood flow in the lung away from edematous segments and toward nonedematous segments. CONCLUSIONS: The inhalation of nitric oxide improves arterial oxygenation in high-altitude pulmonary edema, and this beneficial effect may be related to its favorable action on the distribution of blood flow in the lungs. A defect in nitric nitric oxide synthesis may contribute to high-altitude pulmonary edema.

Administration, Inhalation↗
PubMed2002

Salmeterol for the prevention of high-altitude pulmonary edema.

BACKGROUND: Pulmonary edema results from a persistent imbalance between forces that drive water into the air space and the physiologic mechanisms that remove it. Among the latter, the absorption of liquid driven by active alveolar transepithelial sodium transport has an important role; a defect of this mechanism may predispose patients to pulmonary edema. Beta-adrenergic agonists up-regulate the clearance of alveolar fluid and attenuate pulmonary edema in animal models. METHODS: In a double-blind, randomized, placebo-controlled study, we assessed the effects of prophylactic inhalation of the beta-adrenergic agonist salmeterol on the incidence of pulmonary edema during exposure to high altitudes (4559 m, reached in less than 22 hours) in 37 subjects who were susceptible to high-altitude pulmonary edema. We also measured the nasal transepithelial potential difference, a marker of the transepithelial sodium and water transport in the distal airways, in 33 mountaineers who were prone to high-altitude pulmonary edema and 33 mountaineers who were resistant to this condition. RESULTS: Prophylactic inhalation of salmeterol decreased the incidence of high-altitude pulmonary edema in susceptible subjects by more than 50 percent, from 74 percent with placebo to 33 percent (P=0.02). The nasal potential-difference value under low-altitude conditions was more than 30 percent lower in the subjects who were susceptible to high-altitude pulmonary edema than in those who were not susceptible (P<0.001). CONCLUSIONS: Prophylactic inhalation of a beta-adrenergic agonist reduces the risk of high-altitude pulmonary edema. Sodium-dependent absorption of liquid from the airways may be defective in patients who are susceptible to high-altitude pulmonary edema. These findings support the concept that sodium-driven clearance of alveolar fluid may have a pathogenic role in pulmonary edema in humans and therefore represent an appropriate target for therapy.

Administration, Inhalation↗
PubMed2001

Role of central nervous system nitric oxide in the development of neurogenic pulmonary edema in rats.

OBJECTIVE: The present study was undertaken to evaluate roles of nitric oxide in the central nervous system in the development of neurogenic pulmonary edema. Nitric oxide donor compounds have been reported to be effective for controlling some kinds of pulmonary edema. DESIGN: Randomized trial. SETTING: Experimental university pharmacology laboratory. SUBJECTS: Wistar rats anesthetized with pentobarbital. INTERVENTIONS: Neurogenic pulmonary edema was induced by injections of fibrinogen and thrombin into the cisterna magna. Physiologic roles of nitric oxide were evaluated by using NG-nitro-l-arginine methyl ester (a nitric oxide synthase inhibitor) or l-arginine (a nitric oxide donor compound). Vagus nerves were either left intact or bilaterally severed 20 mins before the injections of fibrinogen and thrombin. MEASUREMENTS AND MAIN RESULTS: Because enhanced sympathetic nerve activity mediates neurogenic pulmonary edema, the concentration of neuropeptide Y, a neurotransmitter, in edema fluid was measured by using enzyme-linked immunosorbent assay. To evaluate the severity of pulmonary edema and pulmonary vascular permeability, lung water content and protein concentration in edema fluid were analyzed. In rats with intact vagus nerves, injection of NG-nitro-l-arginine methyl ester into the cisterna magna worsened the pulmonary edema, whereas l-arginine had no effect. In contrast, in vagotomized rats, l-arginine abrogated pulmonary edema, whereas NG-nitro-l-arginine methyl ester exerted no influence. Likewise, the ratio of edema fluid protein to serum protein and the neuropeptide Y concentration were increased by NG-nitro-l-arginine methyl ester in rats with the vagus nerves intact and were diminished by l-arginine in vagotomized rats. CONCLUSIONS: Neurogenic pulmonary edema is characterized by elevated pulmonary vascular permeability and may be inhibited by nitric oxide production in the medulla oblongata.

Analysis of Variance↗
PubMed1991

Noncardiogenic pulmonary edema following upper airway obstruction. 7 cases and a review of the literature.

Pulmonary edema is a relatively common problem facing most physicians. Its separation into cardiogenic and noncardiogenic or high-permeability variants is crucial to its proper early management. Our understanding of the disease processes producing noncardiogenic pulmonary edema has greatly expanded in the last 2 decades. Upper airway obstruction (UAO) is one of many recently recognized mechanisms which can produce noncardiogenic pulmonary edema. The UAO may be subtle in some patients, making its association with the subsequent pulmonary edema difficult especially for the physician unaware of this entity and the potential risk factors contributing to it. A high index of suspicion for this diagnosis is required in the right clinical settings. Our clinical results support a noncardiogenic basis for pulmonary edema occurring after UAO. Five of our 7 patients had at least 1 identifiable risk factor for the development of peri-intubation UAO and pulmonary edema. Additionally, the onset of pulmonary edema following UAO and the duration of the pulmonary edema varied considerably in our patients. Individuals with additional risk factors for the development of noncardiogenic pulmonary edema developed a more severe form of pulmonary edema associated with other organ-system disease. However, in most individuals, UAO-associated pulmonary edema appears to be a self-limited reversible process once it is recognized and properly treated.

Adolescent↗
PubMed1987

Does interstitial lung edema compress airways and arteries? A morphometric study.

We compared areas and diameters of small airways and arteries in three groups of anesthetized dogs: 1) control (n = 5), 2) hydrostatic edema induced by fluid overload (n = 13), and 3) increased permeability edema induced with alpha-naphthylthiourea (n = 5). We measured pulmonary arterial and wedge pressures in all groups and cardiac output in the hydrostatic edema group. Postmortem, lobes were frozen at functional residual capacity and samples taken for measurements of extravascular lung water (Qwl/dQl) and for light microscopy. We also examined lobes from hydrostatic edema experiments fixed at transpulmonary pressures of 5 and 27 cmH2O. From the histology slides, bronchovascular bundles with respiratory bronchioles (n = 706) and bronchioles (n = 467) were photographed and airway and vessel areas and diameters measured. Alveolar and airway luminal edema were graded. We found that only in hydrostatic edema, pulmonary arterial and wedge pressures increased and vascular resistance fell with fluid infusion. Mean Qwl/dQl values were 3.80 +/- 0.17, 6.81 +/- 0.96, and 9.34 +/- 0.62 (SE) in control, hydrostatic, and increased permeability edema groups, respectively. By quantitative histology, airway and arterial areas and diameters did not decrease in edema and rose with increasing transpulmonary pressure. Variable quantities of air-space edema were seen. We conclude that interstitial edema does not compress small airways or arteries and that other mechanisms, including alveolar and airway luminal edema, may explain reported increases in airway resistance.

Animals↗
PubMed1992

Alterations of filtration coefficients in pulmonary edema of different pathogenesis.

Different pathomechanisms in the development of pulmonary edema are being discussed. We investigated the effect of pathogenetically varying forms of edema on lung vascular barrier function in isolated cell-free perfused rabbit lungs. As an index of permeability, capillary filtration coefficients (Kfc) were determined from the slope of lung weight change over periods of stepwise venous pressure elevation (5, 7.5, and 10 mmHg) before (controls) and 60 min after edema induction. Edema was induced by venous congestion (n = 6), by application of arachidonic acid in the presence of diclofenac sodium (n = 6), and by elastase application (n = 6). Control values ranged from 0.28 to 0.51 ml.min-1 x mmHg-1 x 100 g-1. Kfc was significantly enhanced after edema induction up to 243% of control value in the hydrostatic edema, 357% in the arachidonic acid edema, and 594% in the elastase edema. When the alterations in capillary filtration due to the different types of edema were compared, Kfc was significantly higher in the proteinase edema, indicating an irreversibly damaged barrier function. These data exemplify different pathophysiological characteristics due to the pathogenesis of interstitial edema formation.

Airway Resistance↗
PubMed1998

Enalapril prevents imminent and reduces manifest cerebral edema in stroke-prone hypertensive rats.

BACKGROUND AND PURPOSE: Stroke-prone spontaneously hypertensive rats (SHRSP), subjected to high NaCl intake, show severe hypertension, organ damage, and early death. Preventive treatment with an angiotensin-converting enzyme (ACE) inhibitor is known to reduce mortality. Previously we found that proteinuria always precedes cerebral edema in SHRSP. Hence, in this study ACE inhibition was started later, ie, directly after manifestation of either proteinuria or cerebral edema. METHODS: SHRSP were subjected to 1% NaCl intake. Group 1 served as a control. In group 2 early-onset treatment with the ACE inhibitor enalapril was initiated after proteinuria was >40 mg/d. In group 3 late-onset ACE inhibition was started after the first observation of cerebral edema with T2-weighted MRI. Cerebral edema was expressed as the percentage of pixels with an intensity above a defined threshold. RESULTS: In controls median survival was 54 days (range, 32 to 80 days) after start of salt loading. The terminal level of cerebral edema was 19.0+/-3.0%. Under early-onset enalapril, median survival increased to 320 days (range, 134 to 368 days; P<0.01 versus group 1). Cerebral edema was prevented in all but 1 rat. Systolic blood pressure was slightly and transiently reduced at day 14. Proteinuria was markedly reduced (52+/-7 versus 190+/-46 mg/d in group 1 at day 7; P<0.05). Under late-onset enalapril, median survival was 264 days (range, 154 to 319 days; P<0.01 versus group 1). Cerebral edema decreased to baseline levels (9.6+/-2.9 at day 0 to 3.4+/-0.5% at day 3; (P<0.05). Ultimately cerebral edema reoccurred in 6 of the 8 rats. SBP decreased slightly at day 7 only. Proteinuria decreased from 283+/-27 at day 0 to 116+/-22 mg/d at day 7 (P<0.05). Complete remission of the original locus of cerebral edema was confirmed histologically. CONCLUSIONS: In SHRSP with proteinuria, treatment with an ACE inhibitor both prevented the development of cerebral edema and reduced manifest cerebral edema and proteinuria. Survival was markedly prolonged. These findings support the use of ACE inhibition for treatment in hypertensive encephalopathy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Lung injury edema in dogs. Influence of sympathetic ablation.

Increased vascular permeability characterizes lung injury pulmonary edema and renders fluid balance in the injured lung especially sensitive to changes in hydrostatic pressure. Pulmonary edema is often associated with increased sympathetic nervous system activity which can lead to pulmonary venoconstriction. This postcapillary venoconstriction could raise microvascular pressure and might therefore increase edema in the injured lung. We produced lung injury edema in dogs with oleic acid and directly measured small (less than 2 mm) pulmonary vein pressure. We found that the small pulmonary vein pressure was increased from 9.8 +/- 0.5 mmHg to 12.6 +/- 0.5 mmHg (n = 10) by oleic acid injury edema. The increase was not due to a rise in left atrial pressure since the small pulmonary vein-left atrial pressure gradient also increased. To test if this increase in the postcapillary pressure gradient was sympathetically mediated, we either unilaterally ablated the stellate ganglion or produced unilateral alpha adrenergic blockade with phenoxybenzamine before giving oleic acid. Both of these "antisympathetic" interventions prevented the increase in pulmonary vein pressure caused by oleic acid edema in the protected lung but not in the intact contralateral lung. These interventions produced a 30 +/- 6.8% reduction in the amount of edema caused by oleic acid. Restoring the increase in small vein pressure by inflating a balloon in the left atrium of dogs with bilateral stellate ganglion ablations abolished the reduction in edema produced by antisympathetic treatment. However, the decrease in edema was not significantly correlated with the reduction in pulmonary vein pressure. Thus, the mechanism of the effects of these antisympathetic interventions remains unclear. We conclude that lung injury edema causes sympathetically mediated pulmonary venoconstriction and that antisympathetic interventions significantly reduce lung injury edema and microvascular pressure.

Animals↗
PubMed1990

Role of the blood-nerve barrier in experimental nerve edema.

Nerve edema is a common response to the nerve injury seen in many peripheral neuropathies and is an important component of Wallerian degeneration. However, independent pathologic effects of nerve edema that aggravate or induce nerve injury extend the role of edema beyond that of an epiphenomenon of injury. New insights into the mechanism and impact of nerve edema come largely from animal models. In the following review, we discuss the cause and consequences of nerve edema with particular reference to endoneurial fluid pressure and its relevance to the nerve microenvironment. Experimental models of nerve edema include conditions with increased vascular permeability such as lead poisoning, experimental allergic neuritis, and murine globoid leukodystrophy. Increased perineurial permeability induced by local anesthetics and neurolytic drugs can also induce nerve edema sufficient to increase endoneurial fluid pressure. Both perineurial and vascular permeability are increased after damage induced by crush, freeze, or laser injury. One of the most important forms of nerve edema is induced by external compression; the significance of this change is that edema has local compressive effects that persist after the external pressure has been relaxed. Nerve edema and increased endoneurial fluid pressure also occur in conditions in which vascular permeability appears to be unchanged such as experimental diabetic neuropathy and in hexachlorophene intoxication. In both of these conditions, reduced nerve blood flow has been demonstrated in rats and is viewed as a consequence of increased endoneurial fluid pressure. Whatever its mechanism, endoneurial edema has important structural and functional consequences for nerve fibers. A clear understanding of the underlying pathology of the nerve microenvironment may provide useful insights into treatment of clinical neuropathies.

Animals↗