Re-expansion pulmonary edema. A potential role for free radicals in its pathogenesis

Re-expansion Pulmonary Edema: A Rare Complication of Chest Drain Insertion in Spontaneous Pneumothorax

Re-expansion pulmonary edema (RPE) after chest drain insertion is rare. The objective of this clinical case report is to highlight the importance of this chest drain insertion complication. A 35-year-old man presented to the emergency department with a chief complaint of shortness of breath and pleuritic chest pain. Further physical examination and radiographic investigations showed a left-sided hemipneumothorax. A chest drain was inserted, but subsequently the patient developed worsening shortness of breath, desaturation, and coughed out pink frothy sputum. Repeated chest radiographic and computed tomographic thorax findings suggested RPE. A nonrebreathable mask with high-flow oxygen was given to the patient to maintain his oxygen saturation. The patient was referred to the cardiothoracic team and was admitted to the hospital. Despite conservative management in the ward, the patient underwent lung decortication. Postdecortication, the left-sided lung re-expanded well, and the patient was discharged home. This case highlighted this rare, potentially fatal complication of chest drain insertion for spontaneous pneumothorax.

Perioperative Pulmonary Atelectasis: Part I. Biology and Mechanisms

Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.

Liver Transplant and Reexpansion Pulmonary Edema: A Case Report

Hydrothorax occurs frequently in patients with endstage liver disease and usually requires drainage of pulmonary effusion during the hepatectomy phase of liver transplant. Reexpansion pulmonary edema is a rare but potentially fatal complication seen after rapid reexpansion of the collapsed lung following thoracentesis of pleural fluid or tube drainage of pneumothorax. This condition, which manifests with various degrees of clinical severity, is rarely reported following liver transplantation. Herein, we present a 62-year-old male patient who developed reexpansion pulmonary edema after drainage of massive pleural effusion, which caused a total collapse in the right hemithorax during liver transplant. Six hours after pleural fluid drainage, the patient developed a nonproductive cough, mild tachypnea, shortness of breath, and low oxygen saturation (88%). His chest radiograph showed diffuse heterogeneous opacities in the right hemithorax. Computed tomography of the thorax revealed consolidations containing air bronchograms and ground glass opacities in the parenchyma of the right lung; these findings did not extend to the periphery and were observed less frequently in the inferoposterior left lung. These symptoms and radiologic findings were diagnosed as reexpansion pulmonary edema. Complete clinical and radiologic improvements were achieved within 72 hours of mechanical ventilatory support.

Reexpansion Pulmonary Edema in Pediatrics

Reexpansion pulmonary edema is a rare complication that may occur after drainage of pneumothorax or pleural effusion. A number of factors have been identified that increase the risk of developing reexpansion pulmonary edema, and pathophysiologic mechanisms have been postulated. Patients may present with radiographic findings alone or may have signs or symptoms that prompt evaluation and diagnosis. Clinical presentations range from mild cough to respiratory failure and hemodynamic compromise. Treatment strategies are supportive, and should be tailored to match the severity of the condition.

Complications of thoracentesis: incidence, risk factors, and strategies for prevention

PURPOSE OF REVIEW

Although thoracentesis is generally considered safe, procedural complications are associated with increased morbidity, mortality, and healthcare costs. In this article, we review the risk factors and prevention of the most common complications of thoracentesis including pneumothorax, bleeding (chest wall hematoma and hemothorax), and re-expansion pulmonary edema.

RECENT FINDINGS

Recent data support the importance of operator expertise and the use of ultrasound in reducing the risk of iatrogenic pneumothorax. Although coagulopathy or thrombocytopenia and the use of anticoagulant or antiplatelet medications have traditionally been viewed as contraindications to thoracentesis, new evidence suggests that patients may be able to safely undergo thoracentesis without treating their bleeding risk. Re-expansion pulmonary edema, a rare complication of thoracentesis, is felt to result in part from the generation of excessively negative pleural pressure. When and how to monitor changes in pleural pressure during thoracentesis remains a focus of ongoing study.

SUMMARY

Major complications of thoracentesis are uncommon. Clinician awareness of risk factors for procedural complications and familiarity with strategies that improve outcomes are essential components for safely performing thoracentesis.

Anesthetic management in a patient with giant growing teratoma syndrome: a case report

Introduction

Growing teratoma syndrome is a rare occurrence with an ovarian tumor. Anesthesia has been reported to be difficult in cases of growing teratoma syndrome of the cystic type due to the pressure exerted by the tumor. However, there have been no similar reports with the solid mass type. Here, we report our experience of anesthesia in a case of growing teratoma syndrome of the solid type.

Case presentation

The patient was a 30-year-old Japanese woman who had been diagnosed with an ovarian immature teratoma at age 12 and had undergone surgery and chemotherapy. However, she dropped out of treatment. She presented to our hospital with a 40cm giant solid mass and severe respiratory failure, and was scheduled for an operation. We determined that we could not obtain a sufficient tidal volume without spontaneous respiration. Therefore, we chose to perform awake intubation and not to use a muscle relaxant before the operation. At the start of the operation, when muscle relaxant was first administered, we could not obtain a sufficient tidal volume. An abdominal midline incision was performed immediately and her tidal volume recovered. Her resected tumor weighed 10.5kg. After removal of her tumor, her tidal volume was maintained at a level consistent with that under spontaneous respiration to avoid occurrence of re-expansion pulmonary edema.

Conclusions

We performed successful anesthetic management of a case of growing teratoma syndrome with a giant abdominal tumor. Respiratory management was achieved by avoiding use of a muscle relaxant before the operation to maintain spontaneous respiration and by maintaining a relatively low tidal volume, similar to that during spontaneous respiration preoperatively, after removal of the tumor to prevent re-expansion pulmonary edema.

Fatal re-expansion pulmonary edema in a young adult following tube thoracostomy for spontaneous pneumothorax

Re-expansion pulmonary edema (RPE) is a rare but potentially fatal complication that can occur following rapid lung expansion while managing patients with pleural effusion or pneumothorax. In this case, fatal outcome occurred due to RPE in a previously healthy young adult male patient subsequent to tube thoracostomy for spontaneous pneumothorax. While managing patients with pneumothorax or large pleural effusions, precautions should be taken to avoid rapid re-expansion of the previously collapsed lung in order to reduce the probability of development of this complication.

Amelioration of Ischemia–Reperfusion Injury in an Isolated Rabbit Lung Model Using OXANOH

Objective: Acute respiratory distress syndrome (ARDS) remains a major cause of morbidity and mortality. Oxygen-free radicals (OFRs) produced during ischemia and reperfusion (IR) have been implicated as the final common pathway in the pathogenesis of this syndrome. Spin traps have been shown to decrease IR injury in several animal lung models. The hydroxylamine, OXANOH (2-ethyl-2,5,5-trimethyl-3-oxazolidine) has been proposed as an ideal spin trap that would trap extra- and intracellular OFRs producing the stable radical, OXANO• (2-ethyl-2,5,5-trimethyl-3-oxazolidinoxyl). Electron microscopy was used to investigate whether OXANOH would protect against IR injury in the rabbit lung. Methods: OXANOH was obtained by hydrogenation of its stable radical, OXANO• using a safe laboratory technique. Several doses of OXANOH were tested to identify a nontoxic dose. Two quantitative methods were used based on the average surface area of the alveoli and average number of alveoli per unit surface area using scanning electron microscopy (SEM). A total of 20 animals were subjected to 2 hours of ischemia followed by 4 hours of reperfusion. On reperfusion, the 4 groups (N = 5) received no treatment, OXANOH, superoxide dismutase (SOD)/catalase, or oxypurinol. Results: A therapeutic dose of 250 μmol/L of OXANO• was suggested in this in vitro model. All the 3 treatments showed significantly less injury compared to the control group and that SOD/catalase was significantly different from OXANOH and oxypurinol ( P < .008). Conclusion: OXANOH ameliorated IR injury in the isolated rabbit lung, almost as effectively as SOD/catalase and oxypurinol.

Reexpansion pulmonary edema

A reexpanziós tüdőödéma (RPE) egy ritkán előforduló kórállapot, amely rendszerint a krónikusan kollabált tüdő reexpanziója után jelentkezik. A klinikai manifesztáció széles skálán mozog a tünetmentes betegtől a halálos kimenetelig, amely utóbbi akár az esetek 20%-ában is előfordulhat. A patofiziológiai háttér komplex és máig nem teljesen tisztázott. Az ismert kockázati tényezők szem előtt tartásával és azok lehetőség szerinti kiküszöbölésével akár el is kerülhető az RPE kialakulása. Ez az összefoglaló megpróbál áttekintést adni a jelenlegi ismereteinkről, az RPE hátteréről, a terápiás lehetőségekről. Orv. Hetil., 2010,41,1708–1711.

Application of Pulse Contour Cardiac Output (PiCCO) system for adequate fluid management in a patient with severe reexpansion pulmonary edema

We report a case of severe reexpansion pulmonary edema that occurred immediately after reinflation of a collapsed lung by rapid negative pressure drainage of prolonged malignant pleural effusion and pneumohemothorax. Although hemodynamic stability was difficult to maintain under aggressive treatment with inhalation of nitric oxide, inotropics and prostacyclin infusion, conventional pulmonary artery catheterization was not adequate for surveillance and adjustment of fluid therapy. For balancing the preload and the extent of pulmonary edema, pulse contour cardiac output monitoring using a single transpulmonary thermal dilution technique was applied to achieve optimal cardiac preload for organ perfusion and to prevent worsening of pulmonary edema from fluid overload.

Diagnosis and management of pleural effusions: a practical approach

Pleural effusion is defined as an abnormal amount of pleural fluid accumulation in the pleural space and is the result of an imbalance between excessive pleural fluid formation and pleural fluid absorption. Although the list of causes of pleural effusions is extensive, the great majority of the cases are caused by pneumonia, congestive heart failure, and malignancy. In this article, we provide an overview of the most common causes of pleural effusions likely to be encountered by the general practitioner, and a practical approach to the diagnosis and management of this common condition.

Early perioperative death associated with reexpansion pulmonary edema during liver transplantation

Hydrothorax is a frequent finding in patients with end-stage liver disease. During the hepatectomy phase of liver transplantation, it is often needed to evacuate large pleural effusions. The acute expansion of the collapsed lung can cause reexpansion pulmonary edema with variable clinical significance. However, this complication has rarely been reported after liver transplantation. In conclusion, we report on an overwhelming reexpansion pulmonary edema during a liver transplantation that rapidly led to the patient's demise and speculate if this condition has not been under recognized in the transplantation setting.

Role of Rho-kinase in reexpansion pulmonary edema in rabbits

Reexpansion of a collapsed lung increases the microvascular permeability and causes reexpansion pulmonary edema. Neutrophils and their products have been implicated in the development of this phenomenon. The small GTP-binding proteins Rho and its target Rho-kinase (ROCK) regulate endothelial permeability, although their roles in reexpansion pulmonary edema remain unclear. We studied the contribution of ROCK to pulmonary endothelial and epithelial permeability in a rabbit model of this disorder. Endothelial and epithelial permeability was assessed by measuring the tissue-to-plasma (T/P) and bronchoalveolar lavage (BAL) fluid-to-plasma (B/P) ratios with (125)I-labeled albumin. After intratracheal instillation of (125)I-albumin, epithelial permeability was also assessed from the plasma leak (PL) index, the ratio of (125)I-albumin in plasma/total amount of instilled (125)I-albumin. T/P, B/P, and PL index were significantly increased in the reexpanded lung. These increases were attenuated by pretreatment with Y-27632, a specific ROCK inhibitor. However, neutrophil influx, neutrophil elastase activity, and malondialdehyde concentrations in BAL fluid collected from the reexpanded lung were not changed by Y-27632. In endothelial monolayers, Y-27632 significantly attenuated the H(2)O(2)-induced increase in permeability and mitigated the morphological changes in the actin microfilament cytoskeleton of endothelial cells. These in vivo and in vitro observations suggest that the Rho/ROCK pathway contributes to the increase in alveolar barrier permeability associated with reexpansion pulmonary edema.

A case of unilateral re-expansion pulmonary oedema successfully treated with non-invasive continuous positive airway pressure

Unilateral re-expansion pulmonary oedema is a rare threatening complication of the treatment of lung atelectasis, pleural effusion or pneumothorax, the pathogenesis of which is not completely known. The clinical picture varies considerably from asymptomatic radiological findings to dramatic respiratory failure with circulatory shock. There are few literature reports of the treatment of re-expansion pulmonary oedema with non-invasive continuous positive airway pressure. We present the case of a 75-year-old man who presented in our emergency room with a large left-sided spontaneous pneumothorax and developed severe respiratory failure and circulatory collapse after drainage via a chest tube. The diagnosis of unilateral re-expansion pulmonary oedema was made and he was successfully treated with non-invasive continuous positive airway pressure. Literature data about the aetiological and pathogenetic factors of the condition are also considered.

Acute respiratory distress syndrome of the contralateral lung after reexpansion pulmonary edema of a collapsed lung

STUDY OBJECTIVE

To report that leukocyte-mediated acute injury may develop in a nonhypoxic lung after hypoxia-reoxygenation injury of the hypoxic lung and in other systemic organs in patients with reexpansion pulmonary edema.

DESIGN

Case report analysis with examination of the literature.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Three patients who developed leukocyte-mediated acute lung injury in the contralateral lung and systemic organ injury after ipsilateral reexpansion pulmonary edema of a collapsed lung.

MEASUREMENTS

To rule out the possibility that the acute lung injury in the contralateral lung was an extension of the hypoxia-reoxygenation injury, we analyzed changes in leukocyte and platelet count in the peripheral blood in relation to the development of pulmonary edema in each lung. Changes in liver enzymes were also analyzed to detect hepatic dysfunction as evidence of systemic organ injury.

MAIN RESULTS

Both leukocyte and platelet counts decreased when reexpansion pulmonary edema developed, and decreased further when acute lung injury developed in the contralateral lung (F = 8.42, p = 0.037 for leukocytes, and F = 17.66, p = 0.01 for platelets). Significant hepatic dysfunction developed, as evidenced by increases in both serum bilirubin (p = 0.001) and lactic dehydrogenase, indicating the presence of systemic organ injury.

CONCLUSIONS

The hypoxia-reoxygenation injury of one lung can induce acute lung injury in the other lung and systemic organ injury.

What size chest tube? What drainage system is ideal? And other chest tube management questions

Chest tubes and their accompanying pleural drainage units continue to present challenging questions regarding their optimal use. Appropriate chest tube size selection to accommodate the clinical situation is key, especially in the setting of large pleural air leaks lest a tension pneumothorax ensue. Connection of an appropriate pleural drainage unit to the chest tube is equally important to obviate impeding airflow after successful evacuation by the chest tube. Large-bore chest tubes are generally required for patients with pneumothoraces, regardless of etiology, if the patient is mechanically ventilated, or for patients requiring drainage of viscous pleural liquids such as blood. Smaller bore tubes may be adequate in patients with limited production of pleural air or of free-flowing pleural liquid. Chest tubes may be removed successfully at either end expiration or end inspiration, and potentially as soon as </=200 mL/fluid output per day is achieved. Additional prospective studies are needed to provide evidence-based answers to the many questions remaining regarding chest tube placement, ongoing management, and removal.

Resveratrol modulates rat macrophage functions

This study investigated the effects of trans-resveratrol (trans-3,4',5-trihydroxystilbene, RESV), a natural polyphenol from grapes with known antioxidant activity, on the respiratory-burst responses and phagocytic activity of rat macrophages. RESV at concentrations of 1-10 microM significantly and dose-dependently inhibited (a) the extracellular production of reactive oxygen intermediates (ROls) by resident peritoneal macrophages stimulated with phorbol 12-myristate 13-acetate (PMA) (a potent activator of protein kinase C, PKC) and (b) intracellular production of ROIs after opsonin-independent phagocytosis of Kluyveromyces lactis cells. Over the 10-100 microM concentration ranges, RESV likewise inhibited the production of reactive nitrogen intermediates (RNIs) by macrophages stimulated with thioglycollate. RESV concentrations above 10 microM also dose-dependently inhibited the phagocytosis of K. lactis cells. The results obtained demonstrate that RESV is a potent inhibitor of the antipathogen responses of rat macrophages and, thus, suggest that this agent may have applications in the treatment of diseases involving macrophage hyperresponsiveness.

Complicated negative pressure pulmonary oedema in a child with cerebral palsy

A 3-year-old child with cerebral palsy developed postextubation upper airway obstruction secondary to laryngospasm and/or masseteric spasm,which may have been triggered by the muscular spasticity and the slow recovery from inhalational anaesthesia associated with cerebral palsy. This upper airway obstruction was followed by negative pressure pulmonary oedema. The patient improved on mechanical ventilation; however, his condition was complicated with the occurrence of bilateral pneumothoraces. After release of the pneumothoraces and reexpansion of the lungs, the child developed reexpansion pulmonary oedema, culminating in acute lung injury.

Association of IL-8 and MCP-1 with the development of reexpansion pulmonary edema in rabbits

BACKGROUND

The aim of this study is to determine the relationships between the cytokines and the inflammatory response in reexpansion pulmonary edema (RPE).

METHODS

We examined the cell population, epithelial permeability measured by Evans blue dye (EB), betaglucuronidase and cytokine concentrations in bronchoalveolar lavage fluid (BALF) and/or blood using a rabbit RPE model.

RESULTS

We confirmed that RPE is characterized by recruitment of polymorphonuclear leukocytes (PMNs), the release of PMN granular contents into the air spaces, and increased vascular permeability. These findings were highly correlated with increased interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) concentrations in the BALF. Growth related oncogene (GRO) was detected in the BALF from only 2 of the 7 reexpanded lungs while TNFalpha was not detected in any rabbits. A similar but less severe inflammatory response to the reexpanded lung was found in the contralateral lung.

CONCLUSIONS

IL-8 and MCP-1 may play important roles in the development of RPE; the inflammatory response is independent of TNFalpha and unilateral reexpansion of the lung induces an inflammatory response not only in the reexpanded lung but also in the contralateral lung.

Marked elevation in cortical urate and xanthine oxidoreductase activity in experimental bacterial meningitis

Experimental bacterial meningitis due to Streptococcus pneumoniae in infant rats was associated with a time-dependent increase in CSF and cortical urate that was approximately 30-fold elevated at 22 h after infection compared to baseline. This increase was mirrored by a 20-fold rise in cortical xanthine oxidoreductase activity. The relative proportion of the oxidant-producing xanthine oxidase to total activity did not increase, however. Blood plasma levels of urate also increased during infection, but part of this was as a consequence of dehydration, as reflected by elevated ascorbate concentrations in the plasma. Administration of the radical scavenger alpha-phenyl-tert-butyl nitrone, previously shown to be neuroprotective in the present model, did not significantly affect either xanthine dehydrogenase or xanthine oxidase activity, and increased even further cortical accumulation of urate. Treatment with the xanthine oxidoreductase inhibitor allopurinol inhibited CSF urate levels earlier than those in blood plasma, supporting the notion that urate was produced within the brain. However, this treatment did not prevent the loss of ascorbate and reduced glutathione in the cortex and CSF. Together with data from the literature, the results strongly suggest that xanthine oxidase is not a major cause of oxidative stress in bacterial meningitis and that urate formation due to induction of xanthine oxidoreductase in the brain may in fact represent a protective response.

Lung deflation impairs alveolar epithelial fluid transport in ischemic rabbit and rat lungs

BACKGROUND

Because the fluid transport capacity of the alveolar epithelium after lung ischemia with and without lung deflation has not been well studied, we carried out experimental studies to determine the effect of lung deflation on alveolar fluid clearance.

METHODS

After 1 or 2 hr of ischemia, we measured alveolar fluid clearance using 125I-albumin and Evans blue-labeled albumin concentrations in in vivo rabbit lungs in the presence of pulmonary blood flow and in ex vivo rat lungs in the absence of any pulmonary perfusion, respectively.

RESULTS

The principal results were: (1) lung deflation decreased alveolar fluid clearance while inflation of the lungs during ischemia preserved alveolar fluid clearance in both in vivo and ex vivo studies; (2) alveolar fluid clearance was normal in the rat lungs inflated with nitrogen (thus, alveolar gas composition did not affect alveolar fluid clearance); (3) amiloride-dependent alveolar fluid clearance was preserved when the lungs were inflated during ischemia; (4) terbutaline-simulated alveolar fluid clearance was preserved in the hypoxic rat lungs inflated with nitrogen; (5) lecithinized superoxide dismutase, a scavenger of superoxide anion, and N(omega)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide, preserved normal alveolar fluid clearance in the deflated rat lungs.

CONCLUSION

Lung deflation decreases alveolar fluid clearance by superoxide anion- and nitric oxide-dependent mechanisms.

Approach to the patient in respiratory distress

Respiratory distress is a very common presenting complaint in emergency practice. It is essential that the clinician rapidly determine the underlying cause of the clinical signs using physical examination findings and nonstressful diagnostic tests. Oxygen therapy will often stabilize a patient, allowing for a more complete physical examination and diagnostics, including thoracocentesis, thoracic radiographs, and blood collection for laboratory analysis. The disease processes that cause respiratory distress can be grouped according to anatomic location: the airways, pulmonary parenchyma, pleural space, or thoracic wall. The choice of diagnostic and therapeutic techniques will be dependent on the suspected anatomic origin of disease. Techniques useful in diagnosing airway disorders include oral examination, cervical and thoracic radiographs, fluoroscopy, and bronchoscopy. Therapeutic techniques include intubation and tracheostomy. For parenchymal disease, thoracic radiographs, echocardiography, ultrasound of the thorax, and transtracheal or endotracheal wash can be useful. When the disease process is in the pleural space, thoracocentesis can be both diagnostic and therapeutic. Chest tube placement may be necessary for continuous removal of air or fluid from the pleural space. Monitoring of the respiratory patient can involve serial physical examination, pulse oximetry, and arterial blood gas analysis. It is essential to minimize stress on patients with respiratory distress because decompensation can occur easily, leading to respiratory arrest.

Importance of interleukin-8 in the development of reexpansion lung injury in rabbits

Reexpansion of a collapsed lung induces increased microvascular permeability leading to reexpansion pulmonary edema (REPE). This study was designed to prove the hypothesis that local overproduction of interleukin-8 (IL-8) induces inflammatory cell accumulation which leads to the induction of REPE. Initially, we examined the detailed characteristics of a rabbit model of REPE in association with IL-8 production and its mRNA expression. The lung tissue to plasma ratio of radiolabeled albumin (T/P ratio), the lung wet to dry ratio, and bronchoalveolar lavage (BAL) neutrophil counts were significantly increased in the reexpanded lung. IL-8 concentrations and mRNA expression were significantly increased in the reexpanded lung homogenate. Immunohistochemically, alveolar macrophages (AMs) and epithelial cells in the reexpanded lung and AMs in the collapsed lung were positive for IL-8. Second, we examined the effect of pretreatment with a specific monoclonal anti-IL-8 antibody (Ab) or control IgG on the development of REPE. The T/P ratio and BAL neutrophil counts were conspicuously decreased by pretreatment with anti-IL-8 Ab, but not with control IgG. On a histopathological study, lung injury and leukocyte infiltration were attenuated by the pretreatment with anti-IL-8 Ab. In conclusion, IL-8 production is enhanced in the reexpanded lung, and contributes to the development of REPE. The pretreatment with anti-IL-8 antibody may be useful as a novel protective therapy for this disease.

Lesão pulmonar de reperfusão

A lesão de isquemia-reperfusão constitui-se em um evento fisiopatológico comum a diversas doenças da prática clínica diária. O pulmão pode ser alvo da lesão de isquemia-reperfusão diretamente, como no edema pulmonar após transplante ou na resolução de tromboembolismo; ou ainda ser atingido à distância, como nos casos de choque ou por lesão de reperfusão em intestino ou em membros inferiores, como ocorre no pinçamento da aorta, utilizado nas cirurgias de aneurisma. Dentre os mediadores envolvidos na lesão de isquemia-reperfusão, foram identificados espécies reativas tóxicas de oxigênio (ERTO), mediadores lipídicos, como a tromboxana, moléculas de adesão em neutrófilos e endotélio, fator de necrose tumoral, dentre outros. As medidas terapêuticas para a lesão de reperfusão ainda são utilizadas no plano experimental e em poucos estudos clínicos. São utilizados: antioxidantes, bloqueadores de mediadores lipídicos, inibidores da interação entre leucócito e endotélio ou substâncias que favoreçam o fluxo sanguíneo pós-isquêmico.

[Re-expansion pulmonary edema after excision of an intrathoracic tumor]

We report an acute respiratory insufficiency following the removal of a large intrathoracic fibroma (3.1 kg) in a 6 year-old child, caused by a re-expansion pulmonary oedema (unilateral oedema occurring within one hour after expansion). This oedema improved rapidly and was followed by a well-tolerated pleural effusion. This complication is due to discrepancy between a small lung and a large thoracic cavity, due to the prolonged time course of the tumor growth. These oedemas are caused by rapid lung re-expansion, the volume of the removed tumor and the depth of postoperative pleural suction. The value of positive-end expiratory pressure is discussed.

A proposed biochemical mechanism involving hemoglobin for blast overpressure-induced injury

Blast overpressure (BOP) is the abrupt, rapid, rise in atmospheric pressure resulting from explosive detonation, firing of large-caliber weapons, and accidental occupational explosions. Exposure to incident BOP waves causes internal injuries, mostly to the hollow organs, particularly the ears, lungs and gastrointestinal tract. BOP-induced injury used to be considered of military concern because it occurred mostly in military environments during military actions or training, and to a lesser extent during civilian occupational accidents. However, in recent years with the proliferation of indiscriminate terrorist bombings worldwide involving civilians, blast injury has become a societal concern, and the need to understand the biochemical and molecular mechanism(s) of injury, and to find new and effective methods for treatment gained importance. In general, past BOP research has focused on the physiological and pathological manifestations of incapacitation, thresholds of safety, and on predictive modeling. However, we have been studying the molecular mechanism of BOP-induced injury, and recently began to have an insight into that mechanism, and recognize the role of hemoglobin released during hemorrhage in catalyzing free radical reactions leading to oxidative stress. In this report we discuss the biochemical changes observed after BOP exposure in rat blood and lung tissue, and propose a biochemical mechanism for free radical-induced oxidative stress that can potentially complicate the injury. Moreover, we observed that some antioxidants can interact with Hb oxidation products (oxy-, met- and oxoferrylHb) and act as prooxidants that can increase the damage rather than decrease it.

No obvious advantages for thoracoscopic two-stage oesophagectomy

Thoracoscopically assisted Ivor-Lewis oesophagectomy potentially combines the pulmonary advantages of transhiatal oesophageal dissection, with the visibility and control permitted by thoracotomy. This study reviewed 17 patients who underwent this procedure with an intrathoracic anastomosis. Five patients required conversion to thoracotomy, four because of technical difficulties with the anastomosis. After operation 13 patients had radiological evidence of atelectasis, six developed a left pleural effusion and five had clinically significant pneumonia. Three patients developed an anastomotic leak, two of whom died giving an in-hospital mortality rate of 12 per cent. Median postoperative hospital stay was 12 days. Four patients developed benign anastomotic strictures requiring dilatation. The 1- and 2-year survival rates were 73 per cent (11 of 15 patients) and 63 per cent (five of eight) respectively. The use of minimal access techniques in this context does not appear to reduce the postoperative incidence of either pulmonary or anastomotic complications.

Measurement of superoxide anion production using maximal rate of cytochrome (III) C reduction in phorbol ester stimulated neutrophils, immobilised to microtiter plates

In the present investigation, a method of studying the maximal rate of superoxide anion (O2.-) production in immobilised human neutrophils using a microtiter plate technique has been developed. The rate of O2.- production was determined from the rate of reduction of cytochrome (III) C, studied as the increase in absorbance at 550 nm. The protein kinase C activator, phorbol 12-myristate 13-acetate, was used to stimulate O2.- production. Neutrophils were evenly immobilised as a monolayer to microtiter culture plates to provide a reproducible exposure to the medium. Phorbol ester stimulated O2.- production was inhibited by staurosporine, a well-known inhibitor of protein kinase C, and by diphenylene iodonium, a potent NADPH-oxidase inhibitor, with IC50-values in this assay of 20 and 220 nm, respectively. The extracellularly produced O2.- was removed by superoxide dismutase with a half maximal effect of 0.6 microgram/mL. The maximal production rate of O2.- could therefore be estimated by addition of 20 micrograms/mL superoxide dismutase. Several antioxidants, including butylated hydroxytoluene, nordihydroguairetic acid, probucol and alpha-tocopherol, were studied and showed neither an effect on O2.- production nor a scavenging effect. This new method was highly reproducible, and the continuous measurement of O2.- production was very useful for validating the effect of inhibitors. The developed microtiter technique using immobilised cells has a large capacity and allows different compounds to be tested under comparable conditions, since they are exposed to the cells in a similar way. This is also the first test model which describes O2.- production as the maximal rate of cytochrome (III) C reduction.

Hydrogen peroxide release by mitochondria from normal and hypoxic lungs

Ischemia/reperfusion mechanisms contribute to lung injury after transplantation, pulmonary embolism, and resolution of atelectasis. Alveolar tissue becomes hypoxic and deprived of substrate only when both ventilation and perfusion are interrupted, a situation modeled in vivo by complete, unilateral lung collapse. Because previously hypoxic mitochondria may be an important intracellular source of superoxide and hydrogen peroxide (H2O2) during reperfusion and re-oxygenation, the authors, in this study, investigated whether mitochondrial H2O2 release changed as a result of lung hypoxia/hypoperfusion resulting from collapse. Mitochondria were isolated from hypoxic (previously collapsed) right or contralateral left rabbits' lungs and from control rabbits' lungs. Mitochondrial H2O2 release, a marker of superoxide production, was measured fluorometrically after incubation with or without 1 mmol/L cyanide and 0.1 mmol/L nicotinamide adenine dinucleotide. Mitochondrial recovery was determined by assaying succinate dehydrogenase activity in mitochondrial preparations and lung homogenates. Lung succinate dehydrogenase activity and mitochondrial recovery were comparable among groups. Calculated lung mitochondrial content did not change (control subjects: left 7.9 +/- 0.5, right 13.8 +/- 1.7; hypoxic: left 10.3 +/- 1.3, right 10.5 +/- 2.4, all mg mitochondrial protein/lung). Mitochondria released hydrogen peroxide at approximately 5.6 nmol/h/mg pro in buffer alone and 14.8 nmol/h/mg pro in buffer with cyanide and nicotinamide adenine dinucleotide. However, lung collapse and resulting hypoxia caused no change in mitochondrial number or capacity to release H2O2 in vitro. Based on these findings, it is suggested that other sources of reactive oxygen metabolites, including xanthine oxidase and activated neutrophils, contribute to the oxidant injury observed in this model.

Re-expansion pulmonary oedema following removal of intrathoracic haematoma

Acute ipsilateral pulmonary oedema is a well documented complication of the treatment of lung collapse secondary to pneumothorax, pleural effusion and atelectasis. We present a case of bilateral re-expansion pulmonary oedema following removal of an intrathoracic haematoma. High protein concentration of the oedema fluid suggests increased pulmonary vascular permeability as a cause of this pulmonary oedema.

MnSOD protein content changes in hypoxic/hypoperfused lung tissue

Previous studies using an in vivo rabbit model in which lung tissue hypoxia/hypoperfusion was created by unilateral lung collapse for 7 days demonstrated a decrease in MnSOD activity in previously hypoxic/hypoperfused lungs. In the present study, we determined whether tissue hypoxia/hypoperfusion decreased MnSOD protein concentration or mRNA expression in the lung as well, changes that would suggest pretranslational regulation of enzyme activity. Expression of MnSOD may be critical in determining the degree of tissue injury during re-oxygenation because the mitochondrial electron transport system produces reactive oxygen species (ROS) both during hypoxia and re-oxygenation. We purified MnSOD protein from rabbit livers to a specific activity of approximately 3,500 U/mg protein and found the amino terminal sequence nearly identical to those of the rat and human MnSOD proteins. Lung MnSOD protein content was quantitated by immunoassay, and MnSOD mRNA content was determined by slot blotting. Results from five control and six experimental rabbits, the right lungs of which had been hypoxic/hypoperfused because of collapse for 7 days, demonstrated a 32% decrease (P < 0.03) in MnSOD protein content (42 +/- 8 micrograms/mg DNA in hypoxic lungs compared with 61 +/- 3 micrograms/mg DNA in contralateral lungs) that was not due to decreased numbers of mitochondria. Lung succinate dehydrogenase activity, a mitochondrial marker, did not change in hypoxic/hypoperfused lungs. The mRNA for MnSOD did not change relative to B-actin mRNA in lungs that had been hypoxic and hypoperfused for 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adherent neutrophils mediate permeability after atelectasis

Re-expansion of atelectatic lung is associated with increased permeability. This study tests whether neutrophils mediate this event. Right middle lobar atelectasis was induced in anesthesized rabbits (n = 18) by intraluminal obstruction of the bronchus after a 20-minute ventilation with 100% O2. After 1 hour of bronchial obstruction and 20 minutes after lobar re-expansion, leukopenia was noted, 2870 +/- 210 white blood cells (WBC)/mm3, relative to control animals treated with a noninflated balloon catheter, 6500 +/- 410 WBC/mm3 (p less than 0.05). Three hours after re-expansion, neutrophils were sequestered in the previously atelectatic region 78 +/- 7 polymorphonuclear leukocytes (PMN)/10 high-power field (HPF), as well as in nonatelectatic areas, 40 +/- 3 PMN/10 HPF, higher than control values of 26 +/- 3 PMN/10 HPF (p less than 0.05). In the atelectatic region, neutrophil sequestration was associated with increased protein concentration in lobar bronchoalveolar lavage (BAL) of 1370 +/- 100 micrograms/mL, higher than control values of 270 +/- 20 micrograms/mL (p less than 0.05). Reexpansion also induced increases in lung wet-to-dry weight ratio (W/d) of 6.2 +/- 0.2, higher than control values of 4.3 +/- 0.1 (p less than 0.05). Rendering rabbits neutropenic (n = 18) (0 to 4 PMN/mm3) limited the atelectasis-induced protein accumulations in BAL (520 +/- 60 micrograms/mL) and increase in lung W/d (5.2 +/- 0.1) (both p less than 0.05). Intravenous (I.V.; treatment of another group (n = 18) with an anti-CD 18 monoclonal antibody (R 15.7, 1 mg/kg) before balloon deflation prevented leukopenia (6550 +/- 560 WBC/mm3), minimized neutrophil sequestration (36 +/- 2 PMN/10 HPF), and attenuated protein leak (710 +/- 95 micrograms/mL) and the increased lung W/d (5.6 +/- 0.1) (all p less than 0.05). A final atelectatic group (n = 9) was treated I.V. with the anti-intercellular adhesion molecule-1 monoclonal antibody (RR 1/1, 1 mg/kg), which also prevented leukopenia and showed similar protection of microvascular barrier function. These data indicate that adherent neutrophils in large part mediate lung permeability and edema after atelectasis and re-expansion. Adhesion receptors of both neutrophils and endothelial cells regulate this event.

[Postoperative re-expansion causing unilateral pulmonary edema]

A case of re-expansion pulmonary oedema is reported. A 7-year-old girl, after having been operated on for a lung tumour, had a postoperative haemothorax combined with atelectasis of the left upper lobe. After she had recovered from the first dose of chemotherapy, the thoracotomy wound was reopened to remove the partially organised and lysed haemothorax, as well as the very thickened pleura. The patient developed clinical signs of pulmonary oedema very shortly after the end of the anaesthetic (tachypnoea, cyanosis, a decrease in oxygen saturation when FIO2 < 1, pink frothy secretions in the endotracheal tube). End-inspiratory crepitations became audible in the left lung field only. The chest film showed left-sided diffuse nodular alveolar opacities. The girl was again ventilated, with + 5 cmH2O positive end-expiratory pressure. She was extubated 36 h later, and discharged a few days later without any sequela. This case was the first to be described in a child after pleural surgery. The death rate, estimated from a literature survey, is about 20%.

Initial treatment of pulmonary edema: a physiological approach

An understanding of the physiological principles involved in lung fluid balance is useful in the initial treatment of pulmonary edema. Normally, a very small volume of fluid is filtered from the pulmonary vasculature into the interstitial space. This interstitial fluid enters the pulmonary lymphatics and is transferred to mediastinal lymphatics at an estimated rate of 20 ml/hr. Under abnormal circumstances, fluid filtration may occur at such a rapid rate that it overwhelms the lymphatics and interstitial space and results in alveolar flooding. This may occur as a result of increased pulmonary vascular pressure or increased vascular permeability. The two general goals of initial therapy are (1) to relieve hypoxemia and (2) to reduce pulmonary capillary pressure. Relieving hypoxemia may require the use of supplemental oxygen by nasal prongs or mask, continuous positive airway pressure (CPAP) mask, or even endotracheal intubation and mechanical ventilation. Measures to decrease preload and thereby reduce pulmonary capillary pressure include sitting the patient up, administering a loop diuretic or morphine intravenously, and in some circumstances using sublingual nitroglycerin. After initial treatment is underway, a search for and specific management of the underlying cause of pulmonary edema can proceed.

Thromboxane-induced neutrophil adhesion to pulmonary microvascular and aortic endothelium is regulated by CD18

Thromboxane (Tx) A2 generation and subsequent selective pulmonary sequestration of neutrophils (PMNs) is characteristic of several forms of the adult respiratory distress syndrome (ARDS). Therefore, we examined PMN-dependent adhesion to cultured pulmonary microvessel and aortic endothelium (EC) in response to U46,619 (Tx mimic). Nonstimulated PMNs were two fold more adherent to pulmonary microvessel EC than to aortic EC (P less than 0.01). PMN pretreatment with Tx mimic (10(-6) M) increased adhesion to both types of EC (P less than 0.01). The Tx mimic-induced adhesion was blocked by receptor antagonists to Tx (SQ29,548) and to leukotrienes (FPL55,712), and by the anti-CD18 mAb TS1/18 (P less than 0.01, all cases). Baseline PMN adhesion also was modulated by Tx, leukotrienes, and CD18, for both EC types. These results indicate pulmonary microvessel EC is intrinsically more adhesive for both nonstimulated and stimulated PMNs than aortic EC and that Tx mediates PMN-dependent adhesion by coupled interaction of Tx and LT receptors via CD18 activation.

Second place--Resident Clinical Science Award 1990. A porcine model of chronic endobronchial obstruction

To elucidate the effects of both prolonged lobar atelectasis and subsequent re-expansion in a non-thoracotomized animal, we have developed a chronic, reversible porcine model of endobronchial obstruction. Eight adolescent pigs underwent the bronchoscopic placement of a left lower lobe bronchial plug. The obstruction was left in place for 24 hours. Four pigs then had the balloon bronchoscopically removed, while four controls underwent sham removal of the balloon. All animals showed significant atelectasis of the obstructed lobe compared to non-obstructed lobes at 24 hours. Pulmonary blood flow decreased significantly 24 hours after obstruction compared to pre-obstruction values in the collapsed lobe in all animals. Re-expansion was followed by arterial hypoxemia, which was accompanied by an increase in relative blood flow to the partially re-expanded lobe in the experimental group. No significant changes in lung water content occurred in the study group compared to controls.