The bronchial circulation. Small, but a vital attribute of the lung

Well-controlled mucosal exudation of plasma proteins in airways with intact and regenerating epithelium

Superficial, systemic microcirculations, distinct from the pulmonary circulation, supply the mucosae of human nasal and conducting airways. Non-injurious, inflammatory challenges of the airway mucosa cause extravasation without overt mucosal oedema. Instead, likely reflecting minimal increases in basolateral hydrostatic pressure, circulating proteins/peptides of all sizes are transmitted paracellularly across the juxtaposed epithelial barrier. Thus, small volumes of extravasated, unfiltered bulk plasma appear on the mucosal surface at nasal and bronchial sites of challenge. Importantly, the plasma-exuding mucosa maintains barrier integrity against penetrability of inhaled molecules. Thus, one-way epithelial penetrability, strict localization, and well-controlled magnitude and duration are basic characteristics of the plasma exudation response in human intact airways. In vivo experiments in human-like airways demonstrate that local plasma exudation is also induced by non-sanguineous removal of epithelium over an intact basement membrane. This humoral response results in a protective, repair-promoting barrier kept together by a fibrin-fibronectin net. Plasma exudation stops once the provisional barrier is substituted by a new cellular cover consisting of speedily migrating repair cells, which may emanate from all types of epithelial cells bordering the denuded patch. Exuded plasma on the surface of human airways reflects physiological microvascular-epithelial cooperation in first line mucosal defense at sites of intact and regenerating epithelium.

Bronchial artery diameter in massive hemoptysis in cystic fibrosis

Background

Massive hemoptysis is a rare but potentially life-threatening condition of patients with cystic fibrosis (CF) and advanced pulmonary disease. Hypertrophied bronchial arteries are understood to cause massive hemoptysis when rupturing. Risk factors to predict massive hemoptysis are scarce and bronchial artery diameters are not part of any scoring system in follow-up of patients with CF. Aim of this study was to correlate bronchial artery diameter with massive hemoptysis in CF.

Methods

Bronchial artery and non-bronchial systemic artery diameters were measured in contrast enhanced computed tomography (CT) scans in patients with massive hemoptysis and compared to patients with end-stage CF and no history of hemoptysis. Demographic and clinical data and side of bronchial artery/non-bronchial systemic artery hypertrophy and coil embolization were documented.

Results

In this retrospective multicenter study 33 patients with massive hemoptysis were included for bronchial artery/non-bronchial systemic artery diameter measurements, (13 female, 20 male, median age 30 years (18–55)). Bronchial artery diameters were significantly larger in the case group than in the control group with median 4 mm (2.2–8.2 mm), and median 3 mm (1–7 mm), respectively (p = 0.002). Sensitivity of bronchial arteries ≥ 3.5 mm to be associated with hemoptysis was 0.76 and specificity 0.71 with ROC creating an area under the curve of 0.719. If non-bronchial systemic arteries were present, they were considered culprit and embolized in 92% of cases.

Conclusion

Bronchial arteries ≥ 3.5 mm and presence of hypertrophied non-bronchial systemic arteries correlate with massive hemoptysis in patients with CF and might serve as risk predictor for massive hemoptysis. Therefore, in patients with advanced CF we propose CT scans to be carried out as CT angiography to search for bronchial arteries ≥ 3.5 mm and for hypertrophied non-bronchial systemic arteries as possible risk factors for massive hemoptysis.

[The bronchial arteries: a small but vital contribution to lung perfusion after lung transplantation]

Blood supply to the lungs is carried out by the pulmonary and bronchial-arterial system. The bronchial-arterial vessels are involved in supplying the small airways all the way up to the terminal bronchioles. The bronchial-arterial system is also necessary for the regulation of airway temperature, humidity and mucociliary clearance. Chronic ischaemia of the small airways due to damage or injury to bronchial arterial supply increases the risk of fibrosis of the small airways (bronchiolitis obliteration), especially in lung transplantation (LTx). Although survival after LTx has improved over time, it is, with a 5-year survival rate of only 50 to 60%, still significantly worse than that of other organ transplants. It is likely that bronchial arterial revascularisation at the time of LTx plays an important transplant-preserving function.

Haemoptysis in Pulmonary Arterial Hypertension Associated with Congenital Heart Disease: Insights on Pathophysiology, Diagnosis and Management

Haemoptysis represents one of the most severe major bleeding manifestations in the clinical course of pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD). Accumulating evidence indicates that dysfunction of the pulmonary vascular bed in the setting of PAH predisposes patients to increased hemorrhagic diathesis, resulting in mild to massive and life-threatening episodes of haemoptysis. Despite major advances in PAH targeted treatment strategies, haemoptysis is still correlated with substantial morbidity and impaired quality of life, requiring a multidisciplinary approach by adult CHD experts in tertiary centres. Technological innovations in the field of diagnostic and interventional radiology enabled the application of bronchial artery embolization (BAE), a valuable tool to efficiently control haemoptysis in modern clinical practice. However, bleeding recurrences are still prevalent, implying that the optimum management of haemoptysis and its implications remain obscure. Moreover, regarding the use of oral anticoagulation in patients with haemoptysis, current guidelines do not provide a clear therapeutic strategy due to the lack of evidence. This review aims to discuss the main pathophysiological mechanisms of haemoptysis in PAH-CHD, present the clinical spectrum and the available diagnostic tools, summarize current therapeutic challenges, and propose directions for future research in this group of patients.

Proximal interruption of the pulmonary artery: A review of radiological findings

OBJECTIVES

Proximal interruption of the pulmonary artery (PIPA) has various clinical manifestations. This review focused on and summarized the clinical and radiological features of PIPA, based on relevant literature studies.

METHODS

The study included a total of 25 PIPA cases in the Guangzhou Women and Children's Medical Center between January 2015 and December 2021. Conventional chest photographs and chest computed tomography angiography (CCTA) of patients with PIPA were analyzed and summarized.

RESULTS

The radiological results showed that 17 cases were right-sided and 8 cases were left-sided PIPA. Additionally, the percentage of pulmonary hypoplasia on the affected side was 44%, 36% for pulmonary hypertension, 28% for the mosaic sign, 20% for subpleural cystic lucency shadow, 20% for subpleural serrated shadow, 20% for collateral vessel thickening, 16% for subpleural band-like parenchyma, 12% for pneumonia, and 56% for patent ductus arteriosus.

CONCLUSION

The clinical manifestations of PIPA are non-specific. Awareness of this anomaly, based on radiological manifestations, particularly those observed on CCTA images, is important for ruling out alternative diagnoses and implementing appropriate management.

Six Cases of Hemoptysis with Angiogenesis from Non-Bronchial Systemic Arteries

BACKGROUND Although bronchial arteries are the most common cause of hemoptysis, other systemic arteries can cause hemoptysis and are potential pitfalls for successful embolization. CASE REPORT We present 6 cases of hemoptysis showing vascularization from systemic arteries other than bronchial arteries that presented to our department between 2013 and 2020. Chronic inflammatory diseases such as tuberculosis and pulmonary aspergillosis were the underlying diseases in 4 of the 6 cases. In all 6 cases, the lesions were close to the pleura. The abnormal non-bronchial systemic arteries were the internal thoracic artery in 4 cases, intercostal artery in 2 cases, lateral thoracic artery in 2 cases, and the subclavian, thyrocervical, and inferior phrenic arteries in 1 case each, all of which formed a shunt with the pulmonary artery. Additionally, depending on the location of the lesion, the non-bronchial systemic arteries near the lesion proliferated into the lung parenchyma through the adherent pleura. CONCLUSIONS When lesions are in contact with the pleura, various non-bronchial systemic arteries near the lesion can develop in the pulmonary parenchyma via the adherent pleura, which can cause hemoptysis. In patients with hemoptysis, it may be useful to evaluate chest contrast-enhanced computed tomography and angiography, while always accounting for the potential involvement of non-bronchial systemic arteries to ensure a safer and more reliable treatment.

A Nomogram to Predict Recurrence After Bronchial Artery Embolization for Hemoptysis Due to Bronchiectasis

OBJECTIVE

To develop and validate a nomogram for predicting recurrent hemoptysis after successful bronchial arterial embolization (BAE) in patients with bronchiectasis.

MATERIALS AND METHODS

From January 2015 to December 2019, a total of 251 patients were enrolled in this study. A nomogram was developed with the predictors of recurrent events, which were identified by univariate and multivariate Cox regression analyses. We evaluated nomogram discrimination by area under the receiver operating characteristic curve, calibration by the calibration curve, and clinical usefulness potential by decision curve analysis.

RESULTS

The one-month, 1-year, 2-year, 3-year, and 5-year cumulative recurrence-free rates of patients were 98.4%, 90.5%, 82.8%, 77.7%, and 74.4%, respectively. Three predictive factors, namely sex, lung destruction, and systemic arterial-pulmonary circulation shunts, were applied to develop the nomogram. The model maintained good discrimination (area under the curve, 0.72; 95% confidence interval, 0.62-0.81), low prediction error (integrated Brier score, 0.129), and certain net benefits in terms of clinical usefulness.

CONCLUSIONS

The proposed nomogram showed favorable predictive efficacy for hemoptysis recurrence after BAE in patients with bronchiectasis. Improved long-term outcomes are expected with close follow-up, a healthy lifestyle, and pulmonary rehabilitation for patients at risk of recurrence according to the model.

The force loading rate drives cell mechanosensing through both reinforcement and cytoskeletal softening

Cell response to force regulates essential processes in health and disease. However, the fundamental mechanical variables that cells sense and respond to remain unclear. Here we show that the rate of force application (loading rate) drives mechanosensing, as predicted by a molecular clutch model. By applying dynamic force regimes to cells through substrate stretching, optical tweezers, and atomic force microscopy, we find that increasing loading rates trigger talin-dependent mechanosensing, leading to adhesion growth and reinforcement, and YAP nuclear localization. However, above a given threshold the actin cytoskeleton softens, decreasing loading rates and preventing reinforcement. By stretching rat lungs in vivo, we show that a similar phenomenon may occur. Our results show that cell sensing of external forces and of passive mechanical parameters (like tissue stiffness) can be understood through the same mechanisms, driven by the properties under force of the mechanosensing molecules involved.

Pulmonary route of administration is instrumental in developing therapeutic interventions against respiratory diseases

Pulmonary route of drug delivery has drawn significant attention due to the limitations associated with conventional routes and available treatment options. Drugs administered through pulmonary route has been an important research area that focuses on to developing effective therapeutic interventions for asthma, chronic obstructive pulmonary disease, tuberculosis, lung cancer etc. The intravenous route has been a natural route of delivery of proteins and peptides but associated with several issues including high cost, needle-phobia, pain, sterility issues etc. These issues might be addressed by the pulmonary administration of macromolecules to achieving an effective delivery and efficacious therapeutic impact. Efforts have been made to develop novel drug delivery systems (NDDS) such as nanoparticles, microparticles, liposomes and their engineered versions, polymerosomes, micelles etc to achieving targeted and sustained delivery of drug(s) through pulmonary route. Further, novel approaches such as polymer-drug conjugates, mucoadhesive particles and mucus penetrating particles have attracted significant attention due to their unique features for an effective delivery of drugs. Also, use of semi flourinated alkanes is in use for improvising the pulmonary delivery of lipophilic drugs. Present review focuses on to unravel the mechanism of pulmonary absorption of drugs for major pulmonary diseases. It summarizes the development of interventional approaches using various particulate and vesicular drug delivery systems. In essence, the orchestrated attempt presents an inflammatory narrative on the advancements in the field of pulmonary drug delivery.

Bronchial Artery Embolization, an Increasingly Used Method for Hemoptysis; Treatment and Avoidance

Objectives

Hemoptysis is an alarming symptom. It may cause some severe life-threatening complications. Hypertrophic and fragile bronchial artery causes hemoptysis and occurs mostly in bronchiectasis, sarcoidosis, active or sequelae tuberculosis, aspergilloma, lung cancer or cystic fibrosis. Bronchial artery embolization is one of the angiographic methods used in diagnosis and treatment for years performed by radiologists. Hemoptysis is used mostly in patients with hemoptysis. Using this method, surgical management with high mortality and morbidity rates can be avoided or better conditions for surgery can be provided via stopping hemorrhage before surgery. We aim to share the experiences of our hospital about patients who underwent bronchial artery embolization and compare our results with the literature.

Methods

Thirty-nine patients (29 male, 10 female) underwent angiography-aiming embolization. Pathologies were hemoptysis in 37 patients, Castleman disease in two patients. Embolization was performed in 33 patients; 31 for hemoptysis, two for Castleman disease. Bilateral embolization was performed in six patients.

Results

Computed tomography (CT) was helpful in diagnosing the side of bleeding in 91.8% of the patients with hemoptysis. Bronchoscopy was diagnostic in 53% of patients. Polyvinyl alcohol (n=27) was mostly used for embolization. Hemoptysis recurred in six patients (19.3%). All were managed successfully, of four with re-embolization. One major complication, transient blindness, was observed.

Conclusion

Bronchial artery embolization is minimally invasive, more tolerable compared to surgery can be managed with high success and lower complication rates, especially hemoptysis and in some other situations. It provides time for evaluating the underlying disease and delaying surgery for elective conditions. That is why this method has been used increasingly.

Non-bronchial causes of haemoptysis: imaging and interventions

Purpose

To describe non-bronchial causes of haemoptysis on imaging and the role of interventional radiology in their management from cases of haemoptysis archived from our database at a tertiary care, federally funded institution.

Material and methods

Retrospective analysis of cases that presented with haemoptysis in our institution from 2008 to 2013 was done, and details of cases in which the bleeding was from a non-bronchial source were archived and details of imaging and treatment were recorded.

Results

Retrospective analysis of patients presenting with haemoptysis yielded 24 (n = 24) patients having haemoptysis from non-bronchial sources. Causes of haemoptysis were: Rasmussen aneurysms (n = 12/24), costocervical trunk pseudoaneurysm (n = 1/24), left internal mammillary artery pseudoaneurysm (n = 1/24), left ventricular aneurysms (n = 3/24), pulmonary arteriovenous malformations (AVMs) (n = 5/24), and proximal interruption of pulmonary artery (n = 2/24). Imaging and interventional radiology management are described in detail.

Conclusions

Haemoptysis can be from non-bronchial sources, which may be either from systemic or pulmonary arteries or cardio-pulmonary fistulas. Bronchial computed tomography angiography (CTBA), if feasible, must always be considered before bronchial artery embolisation because it precisely identifies the source of haemorrhage and vascular anatomy that helps the interventional radiologist in pre-procedural planning. This circumvents chances of re-bleed if standard bronchial artery embolisation is done without CTBA.

Beyond the Lungs: Systemic Manifestations of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease characterized by progressive loss and remodeling of the pulmonary arteries, resulting in right heart failure and death. Until recently, PAH was seen as a disease restricted to the pulmonary circulation. However, there is growing evidence that patients with PAH also exhibit systemic vascular dysfunction, as evidenced by impaired brachial artery flow-mediated dilation, abnormal cerebral blood flow, skeletal myopathy, and intrinsic kidney disease. Although some of these anomalies are partially due to right ventricular insufficiency, recent data support a mechanistic link to the genetic and molecular events behind PAH pathogenesis. This review serves as an introduction to the major systemic findings in PAH and the evidence that supports a common mechanistic link with PAH pathophysiology. In addition, it discusses recent studies describing morphological changes in systemic vessels and the possible role of bronchopulmonary anastomoses in the development of plexogenic arteriopathy. On the basis of available evidence, we propose a paradigm in which metabolic abnormalities, genetic injury, and systemic vascular dysfunction contribute to systemic manifestations in PAH. This concept not only opens exciting research possibilities but also encourages clinicians to consider extrapulmonary manifestations in their management of patients with PAH.

Drug Absorption Parameters Obtained Using the Isolated Perfused Rat Lung Model Are Predictive of Rat In Vivo Lung Absorption

The ex vivo isolated perfused rat lung (IPL) model has been demonstrated to be a useful tool during drug development for studying pulmonary drug absorption. This study aims to investigate the potential use of IPL data to predict rat in vivo lung absorption. Absorption parameters determined from IPL data (ex vivo input parameters) in combination with intravenously determined pharmacokinetic data were used in a biopharmaceutics model to predict experimental rat in vivo plasma concentration-time profiles and lung amount after inhalation of five different inhalation compounds. The performance of simulations using ex vivo input parameters was compared with simulations using in vitro input parameters, to determine whether and to what extent predictability could be improved by using input parameters determined from the more complex ex vivo model. Simulations using ex vivo input parameters were within twofold average difference (AAFE < 2) from experimental in vivo data for all compounds except one. Furthermore, simulations using ex vivo input parameters performed significantly better than simulations using in vitro input parameters in predicting in vivo lung absorption. It could therefore be advantageous to base predictions of drug performance on IPL data rather than on in vitro data during drug development to increase mechanistic understanding of pulmonary drug absorption and to better understand how different substance properties and formulations might affect in vivo behavior of inhalation compounds.

Management of life-threatening hemoptysis

It is estimated that 5-14% of patients presenting with hemoptysis will have life-threatening hemoptysis, with a reported mortality rate between 9 and 38%. This manuscript provides a comprehensive literature review on life-threatening hemoptysis, including the etiology and mechanisms, initial stabilization, and management of patients. There is no consensus on the optimal diagnostic approach to life-threatening hemoptysis, so we present a practical approach to utilizing chest radiography, computed tomography, and bronchoscopy, alone or in combination, to localize the bleeding site depending on patient stability. The role of angiography and embolization as well as bronchoscopic and surgical techniques for the management of life-threatening hemoptysis is reviewed. Through case presentation and flow diagram, an overview is provided on how to systematically evaluate and treat the bronchial arteries, which are responsible for hemoptysis in 90% of cases. Treatment options for recurrent hemoptysis and definitive management are discussed, highlighting the role of bronchial artery embolization for recurrent hemoptysis.

Efficacy and Safety of Bronchial Artery Embolization on Hemoptysis in Chronic Thromboembolic Pulmonary Hypertension: A Pilot Prospective Cohort Study

Supplemental Digital Content is available in the text.

Objectives:

Managing hemoptysis in chronic thromboembolic pulmonary hypertension can be challenging due to the difficulties in maintaining coagulation homeostasis in affected patients. In this study, we evaluated the efficacy and safety of bronchial artery embolization in treating hemoptysis in chronic thromboembolic pulmonary hypertension patients.

Design:

Pilot, prospective cohort study.

Setting:

A large respiratory medical institute.

Patients:

From January 1, 2012, to December 31, 2017, hospitalized chronic thromboembolic pulmonary hypertension patients were eligible for inclusion. Patients with pulmonary hypertension caused by other conditions, or who failed to participate in the follow-up were excluded.

Interventions:

Hemoptysis in chronic thromboembolic pulmonary hypertension patients was treated with or without bronchial artery embolization based on whether the bleeding could be stopped with medication alone and patient willingness for bronchial artery embolization treatment.

Measurements and Main Results:

A total of 328 patients diagnosed with chronic thromboembolic pulmonary hypertension were consecutively collected, 317 patients were completed the follow-up. There were 15 chronic thromboembolic pulmonary hypertension patients with hemoptysis in total, and the occurrence rate of hemoptysis in chronic thromboembolic pulmonary hypertension patients was 4.7%. Among the hemoptysis chronic thromboembolic pulmonary hypertension patients, 10 (67%) underwent bronchial artery embolization, and five (33%) were treated with medication only. The median follow-up period for hemoptysis patients was 7.6 months. In patients underwent bronchial artery embolization treatment, oxygenation index and right heart function showed no significant difference between pre bronchial artery embolization and post bronchial artery embolization. Hemoptysis relapse (20% vs 80%; p = 0.025) and hemoptysis-related mortality (0% vs 40%; p = 0.032) were significantly lower, whereas the overall survival (90% vs 40%; p = 0.040) was higher in patients treated with bronchial artery embolization than in patients treated without bronchial artery embolization.

Conclusions:

Bronchial artery embolization procedure demonstrated effectiveness and safety to treat hemoptysis in chronic thromboembolic pulmonary hypertension patients at our center, but further controlled studies are needed before it can be considered as an effective therapy for these patients.

Management of hemoptysis in patients with lung cancer

Hemoptysis related to malignancy is common and accounts for nearly a quarter of all cases of hemoptysis in the US, and approximately 20% of patients with lung cancer will experience some degree of hemoptysis during their disease course. Both minor and massive hemoptysis come with diagnostic and treatment challenges and are associated with increased mortality. We will discuss the definition and epidemiology of hemoptysis related to malignancy, outline our approach to the initial evaluation and diagnostic workup, and extensively review the management of minor and massive hemoptysis. Specific emphasis will be on relevant signs and symptoms, imaging, and the role of bronchoscopy, and the differences in approach for minor hemoptysis compared to massive hemoptysis. While the role of surgical management is very limited in this patient population, the role of endobronchial and endovascular management will be discussed in detail.

Left lower lobectomy and partial preservation of segmental arteries of left upper lobe: A strategy to avoid pneumonectomy in selected cases

In this article we report two cases of left lower lobe lung cancer undergoing a surgical procedure that allowed the preservation of lung parenchyma and avoided pneumonectomy. The first case concerned a left lower lobe non‐small cell lung cancer with extracapsular spread in a metastatic interlobar lymph node and the second a left lower lobe lung cancer with invasion of the pulmonary artery at the origin of lobar branches to the lower lobe. In both cases, a lung‐sparing surgical treatment was preferred and a left lower lobectomy was performed with division of lingular arteries and the interlobar artery, preserving the remaining arterial branches to the upper lobe.

Inhaled Cisplatin for NSCLC: Facts and Results

Although we have new diagnostic tools for non-small cell lung cancer, diagnosis is still made in advanced stages of the disease. However, novel treatments are being introduced in the market and new ones are being developed. Targeted therapies and immunotherapy have brought about a bloom in the treatment of non-small cell lung cancer. Still we have to find ways to administer drugs in a more efficient and safe method. In the current review, we will focus on the administration of inhaled cisplatin based on published data.

The Diagnosis and Treatment of Hemoptysis

BACKGROUND

Hemoptysis, i.e., the expectoration of blood from the lower airways, has an annual incidence of approximately 0.1% in ambulatory patients and 0.2% in inpatients. It is a potentially life-threatening medical emergency and carries a high mortality.

METHODS

This review article is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Hemoptysis can be a sign of many different diseases. Its cause remains unknown in about half of all cases. Its more common recognized causes include infectious and inflammatory airway diseases (25.8%) and cancer (17.4%). Mild hemoptysis is self-limited in 90% of cases; massive hemoptysis carries a worse prognosis. In patients whose life is threatened by massive hemoptysis, adequate oxygenation must be achieved through the administration of oxygen, positioning of the patient with the bleeding side down (if known), and temporary intubation if necessary. A thorough diagnostic evaluation is needed to identify the underlying pathology, site of bleeding, and vascular anatomy, so that the appropriate treatment can be planned. The evaluation should include conventional chest x-rays in two planes, contrastenhanced multislice computerized tomography, and bronchoscopy. Hemostasis can be achieved at bronchoscopically accessible bleeding sites with interventionalbronchoscopic local treatment. Bronchial artery embolization is the first line of treatment for hemorrhage from the pulmonary periphery; it is performed to treat massive or recurrent hemoptysis or as a presurgical measure and provides successful hemostasis in 75-98% of cases. Surgery is indicated if bronchial artery embolization alone is not successful, or for special indications (traumatic or iatrogenic pulmonary/vascular injury, refractory asper gilloma).

CONCLUSION

The successful treatment of hemoptysis requires thorough diagnostic evaluation and close interdisciplinary collaboration among pulmonologists, radiologists, and thoracic surgeons.

The Rationale and Evidence for Use of Inhaled Antibiotics to Control Pseudomonas aeruginosa Infection in Non-cystic Fibrosis Bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFBE) is a chronic inflammatory lung disease characterized by irreversible dilation of the bronchi, symptoms of persistent cough and expectoration, and recurrent infective exacerbations. The prevalence of NCFBE is on the increase in the United States and Europe, but no licensed therapies are currently available for its treatment. Although there are many similarities between NCFBE and cystic fibrosis (CF) in terms of respiratory symptoms, airway microbiology, and disease progression, there are key differences, for example, in response to treatment, suggesting differences in pathogenesis. This review discusses possible reasons underlying differences in response to inhaled antibiotics in people with CF and NCFBE. Pseudomonas aeruginosa infections are associated with the most severe forms of bronchiectasis. Suboptimal levels of antibiotics in the lung increase the mutation frequency of P. aeruginosa and lead to the development of mucoid strains characterized by formation of a protective polysaccharide biofilm. Mucoid strains of P. aeruginosa are associated with a chronic infection stage, requiring long-term antibiotic therapy. Inhaled antibiotics provide targeted delivery to the lung with minimal systemic toxicity and adverse events compared with oral/intravenous routes of administration, and they could be alternative treatment options to help address some of the treatment challenges in the management of severe cases of NCFBE. This review provides an overview of completed and ongoing trials that evaluated inhaled antibiotic therapy for NCFBE. Recently, several investigators conducted phase 3 randomized controlled trials with inhaled aztreonam and ciprofloxacin in patients with NCFBE. While the aztreonam trial results were not associated with significant clinical benefit in NCFBE, initial results reported from the inhaled ciprofloxacin (dry powder for inhalation and liposome-encapsulated/dual-release formulations) trials hold promise. A more targeted approach could identify specific populations of NCFBE patients who benefit from inhaled antibiotics.

A systematic approach to the management of massive hemoptysis

Massive hemoptysis is regarded as a potentially lethal condition that requires immediate attention, and prompt action. Although minor hemoptysis is frequently encountered by most clinicians, massive hemoptysis in far less frequent and most physicians are not prepared to manage this time-sensitive clinical presentation in a systematic and timely fashion. Critical initial steps in management need to be implemented in an expedited fashion, such that patients may have a chance at a more definitive treatment. In this article, we review the definition, vascular anatomy, etiology, diagnostic evaluation, epidemiology and prognostic markers of massive hemoptysis. A systematic approach to management, stabilization and treatment options is followed. An algorithm is proposed for the management of massive hemoptysis and the importance of a multidisciplinary approach is emphasized.

Rationale of Using Dynamic Imaging for Characterization of Suspicious Lung Masses into Benign or Malignant on Contrast Enhanced Multi Detector Computed Tomography

Objectives:

To assess the utility of dynamic imaging namely, wash-in and wash-out characteristics through multidetector contrast-enhanced computed tomography in differentiating benign and malignant pulmonary masses.

Materials and Methods:

Seventy-three patients who were suspected to have malignant pulmonary mass on the basis of clinical symptoms and chest radiograph were included in the study. All the patients underwent multidetector computed tomography scanning, and three series of images were obtained for each patient-noncontrast, early enhanced, and 15 min delayed enhanced scans. Computed tomography (CT) findings were assessed in terms of washin, absolute, and relative percentage washout of contrast. Biopsy of the mass was done and sent for histopathological evaluation. Sensitivity, specificity, and area under curve for diagnosing malignancy in the lung masses were calculated by considering both the wash-in and wash-out characteristics at dynamic CT and plotting the receiver operating curve after the final diagnosis which was obtained by histopathological evaluation.

Results:

Threshold net enhancement (washin) value of >22.5 HU had sensitivity, specificity, and diagnostic accuracy of 88.5%, 57.1%, and 82%, respectively, in predicting malignancy. Threshold relative percentage washout of <16.235% had 98.1%, 85.7%, and 94% sensitivity, specificity, and diagnostic accuracy, respectively, and threshold absolute percentage washout of <42.72% had 98.1%, 95.2%, and 95% sensitivity, specificity, and diagnostic accuracy, respectively, in predicting malignancy.

Conclusion:

Threshold net enhancement (washin), absolute and relative washout percentages can be used to predict malignancy with very high diagnostic yield, and possibly obviate the need of invasive procedures for diagnosis of bronchogenic carcinoma.

Pulmonary delivery of nanoparticle chemotherapy for the treatment of lung cancers: challenges and opportunities

Lung cancer is the second most prevalent and the deadliest among all cancer types. Chemotherapy is recommended for lung cancers to control tumor growth and to prolong patient survival. Systemic chemotherapy typically has very limited efficacy as well as severe systemic adverse effects, which are often attributed to the distribution of anticancer drugs to non-targeted sites. In contrast, inhalation routes permit the delivery of drugs directly to the lungs providing high local concentrations that may enhance the anti-tumor effect while alleviating systemic adverse effects. Preliminary studies in animals and humans have suggested that most inhaled chemotherapies are tolerable with manageable pulmonary adverse effects, including cough and bronchospasm. Promoting the deposition of anticancer drugs in tumorous cells and minimizing access to healthy lung cells can further augment the efficacy and reduce the risk of local toxicities caused by inhaled chemotherapy. Sustained release and tumor localization characteristics make nanoparticle formulations a promising candidate for the inhaled delivery of chemotherapeutic agents against lung cancers. However, the physiology of respiratory tracts and lung clearance mechanisms present key barriers for the effective deposition and retention of inhaled nanoparticle formulations in the lungs. Recent research has focused on the development of novel formulations to maximize lung deposition and to minimize pulmonary clearance of inhaled nanoparticles. This article systematically reviews the challenges and opportunities for the pulmonary delivery of nanoparticle formulations for the treatment of lung cancers.

Hypoxic Pulmonary Vasoconstriction in Humans: Tale or Myth

Hypoxic Pulmonary vasoconstriction (HPV) describes the physiological adaptive process of lungs to preserves systemic oxygenation. It has clinical implications in the development of pulmonary hypertension which impacts on outcomes of patients undergoing cardiothoracic surgery. This review examines both acute and chronic hypoxic vasoconstriction focusing on the distinct clinical implications and highlights the role of calcium and mitochondria in acute versus the role of reactive oxygen species and Rho GTPases in chronic HPV. Furthermore it identifies gaps of knowledge and need for further research in humans to clearly define this phenomenon and the underlying mechanism.

Surgical anatomy of the tracheobronchial tree

Airway surgery is often indicated in the management of benign or malignant pathological processes of the tracheobronchial tree. The surgeon undertaking this type of work has, however, the responsibility of understanding the particular anatomy applicable to these structures and procedures as well as be able to correlate imaging, intraoperative findings and anatomy. These are important considerations if one wants to reduce operative morbidity and improve potential for better long-term results. This paper reviews the most important anatomic features of the tracheobronchial tree putting emphasis on those features that are important to surgeons performing surgical procedures on those organs.

Experimental studies in the bronchial circulation. Which is the ideal animal model?

BACKGROUND

The importance of the role of bronchial arteries is notable in modern days thoracic surgery. The significance of their anastomoses with adjusted structures has not yet been sufficiently rated, especially in cases of haemoptysis, heart-lung transplantations and treatment of aneurysms of the thoracic aorta. The need of a thorough study is more relevant than ever and appropriate laboratory animals are required.

METHODS

We review the literature in order to highlight the ideal experimental animal for the implementation of pilot programs relative to the bronchial circulation. A comparative analysis of the anatomy of the bronchial arterial system in humans along with these of pigs, dogs, rats, and birds, as being the most commonly used laboratory animals, is presented in details.

RESULTS

The pig has the advantage that the broncho-oesophageal artery usually originates from the aorta as a single vessel, which makes the recognition and dissection of the artery easy to perform. In dogs, there is significant anatomical variation of the origin of the bronchial arteries. In rats, bronchial artery coming from the aorta is a rare event while in birds the pattern of the bronchial artery tree is clearly different from the human analog.

CONCLUSIONS

The pig is anatomically and physiologically suited for experimental studies on the bronchial circulation. The suitable bronchial anatomy and physiology along with the undeniable usefulness of the pig in experimental research and the low maintenance cost make the pig the ideal model for experiments in bronchial circulation.

Histologic evidence of intrapulmonary anastomoses by three-dimensional reconstruction in severe bronchopulmonary dysplasia

RATIONALE

Bronchopulmonary dysplasia (BPD) is the chronic lung disease of infancy that occurs in premature infants after oxygen and ventilator therapy for acute respiratory disease at birth. Despite improvement in current therapies, the clinical course of infants with BPD is often characterized by marked hypoxemia that can become refractory to therapy. Preacinar anatomic and functional communications between systemic and pulmonary vascular systems has been established in fetal lungs, but whether increased intrapulmonary anastomotic vessels or their failure to regress after birth contributes to hypoxemia in preterm infants with BPD is unknown.

OBJECTIVES

We sought to find histologic evidence of intrapulmonary anastomotic vessels in lungs of patients who died of severe BPD.

METHODS

We collected lung tissues from fatal BPD cases and performed histology, immunohistochemistry, and high-precision three-dimensional reconstruction techniques.

MEASUREMENTS AND MAIN RESULTS

We report histologic evidence of intrapulmonary vessels that bridge pulmonary arteries and veins in the distal lungs of infants dying with severe BPD. These prominent vessels appear similar to "misaligned pulmonary veins" described in the lethal form of congenital lung disorder, alveolar capillary dysplasia.

CONCLUSIONS

We found striking histological evidence of precapillary arteriovenous anastomotic vessels in the lungs of infants with severe bronchopulmonary dysplasia. We propose that persistence or expansion of these vessels after premature birth provides the anatomic basis for intrapulmonary shunt and hypoxemia in neonates with severe bronchopulmonary dysplasia and may play a significant role in the morbidity and mortality of BPD.

Dynamic CT of solitary pulmonary nodules: comparison of contrast medium distribution characteristic of malignant and benign lesions

BACKGROUND

To prospectively assess the role of the dynamic contrast-enhanced CT enhancement characteristics in distinguishing malignant form of benign solitary pulmonary nodules.

METHODS

The study included 87 patients (59 men, 28 women; median age, 59 years) with 87 solitary pulmonary nodules. In all cases, dynamic CT images were obtained before and 20, 30, 45, 60, 75, 90, 120 s, 3, 5, 9, 12, 15 and 20 min after injection of contrast medium. Peak enhancement attenuation value, net enhancement attenuation value, the slope of enhancement, enhancement ratio, outflow of contrast medium (washout), washout ratio and the slope of washout ratio were assessed. Statistical analyses were performed with the Mann-Whitney test, χ(2) test, and receiver-operating characteristic curves.

RESULTS

There were 52 malignant and 35 benign nodules. There were no significant differences in net enhancement value, enhancement ratio and the slope of enhancement ratio between malignant and benign nodules (P > 0.05). Malignant nodules showed smaller outflow of contrast medium than did benign nodules. With 12.4HU or lower washout as a cutoff value, the sensitivity and specificity for malignancy were 52.5 and 65.0 %, respectively. With 18.9 % or lower washout ratio as a cutoff value, sensitivity and specificity for malignancy were 60.0 and 75.0 %, respectively. With 0.0180 %/s or lower slope of washout ratio as a cutoff value, sensitivity and specificity for malignancy were 60.0 and 80.0 %, respectively.

CONCLUSIONS

Dynamic contrast-enhanced CT is helpful in differentiating malignant from benign solitary pulmonary nodules. Smaller washout of contrast enhancement is a predictor that a lesion is malignant.

Right side of heart failure

The function of the right ventricle (RV) in heart failure (HF) has been mostly ignored until recently. A 2006 report of the National Heart, Lung, and Blood Institute identified a gap between RV research efforts and its clinical importance compared with that of the left ventricle. This recent shift in paradigm is fueled by the prognostic value ascribed to RV failure in HF and morbidity/mortality after myocardial infarction and surgery. In this review, we examine the significance of RV failure in the HF setting, its clinical presentation and pathophysiology, and ways to evaluate RV function using echocardiographic measurements. Furthermore, we discuss the medical management of RV failure including traditional therapies like beta-blockers and newer options like nitric oxide, phosphodiesterase inhibitors, and calcium sensitizers. Mechanical support is also examined. Finally, this review places an emphasis on RV failure in the setting of left ventricular assist devices and heart transplantation.

Clinical implications of haemoptysis in patients with pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a disabling disease that may result in haemoptysis. Patients with congenital heart disease associated PAH (CHD-APAH) may have a survival advantage when compared with patients with other types of PAH presenting with haemoptysis. The effects of aetiology and subsequent management choice of haemoptysis in PAH patients is not well-defined.

METHODS

We conducted outcome analysis in CHD-APAH vs. all other subtypes of PAH patients presenting with haemoptysis to The Methodist Hospital. Twenty-one patients were identified, 13 patients in the CHD-APAH group and eight patients in the non-CHD group. We evaluated outcomes related to treatment (bronchial artery embolisation (BAE) vs. conservative management), hospital length of stay, mortality rates and survival in this cohort.

RESULTS

The CHD-APAH and non-CHD groups had similar baseline demographic, haemodynamic and laboratory values except BMI was higher in the non-CHD group and haematocrit was higher in the CHD-APAH group. Twenty-eight-day mortality (0% vs. 31%) and 1-year mortality (0% vs. 54%) was lower in the CHD-APAH patients as compared with non-CHD group. A statistically significant difference was found in the survival rate in favour of CHD-APAH group for the total follow-up period (p = 0.02). Although not statistically significant, patients treated with BAE had shorter length of stay (4.0 days ± 4.0 vs. 13.7 days ± 22.5; p = 0.26). There was recurrent haemoptysis in 43% of patients treated with BAE.

CONCLUSION

Haemoptysis in PAH patients is a serious event with a high mortality rate. CHD-APAH seems to confer a survival advantage, independent of therapy utilised. Termination of haemoptysis with BAE is rapid with relatively few complications except for frequent re-bleeding episodes. Further studies are needed to determine the risk factors that may predispose PAH patients to excessive mortality from haemoptysis and to identify an optimal therapeutic modality.

Airway exchange of highly soluble gases

Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol.

Bronchial artery embolization for hemoptysis

Bronchial artery angiography with embolization has become a mainstay in the treatment of hemoptysis. Major complications are rare and immediate clinical success defined as cessation of hemorrhage ranges in most series from 85% to 100%, although recurrence of hemorrhage ranges from 10% to 33%. Bronchial artery embolization offers a minimally invasive procedure for even the most compromised patient serving as first-line treatment for hemorrhage as well as providing a bridge to more definitive medical or surgical intervention focused upon the etiology of the hemorrhage. The aim of this article is to summarize the etiologies, pathophysiology, and the diagnostic and management strategies of hemoptysis as related to bronchial artery embolization. In addition, the techniques of arteriography and embolization as well as associated procedural outcomes and complications are delineated.

[Bronchial and nonbronchial systemic artery embolization in managing haemoptysis: 31 years of experience]

PURPOSE

The authors report on 31 years of experience with bronchial (BAE) and/or nonbronchial (NBAE) systemic artery embolisation for managing haemoptysis.

MATERIALS AND METHODS

A total of 534 patients who underwent bronchial artery angiography for haemoptysis between 1979 and 2010 were retrospectively evaluated. Of these patients, 477 (89%) had active bleeding and underwent BAE and/or NBAE (295 males and 182 females, aged between 12 and 71 years). Embolisation techniques, materials, major and minor complications and relapses were recorded.

RESULTS

Complete resolution of haemoptysis was achieved within 24 h in 458/477 (96%) cases and within 48 h in 2% of cases. The aetiology of haemoptysis was as follows: cystic fibrosis (23%), bronchiectasis (13%), tuberculosis sequelae (8%), chronic obstructive pulmonary disease (COPD) (6%) and no apparent cause (21%). Major complications were recorded in 3/477 (0.6%): stroke (n=1), transient ischaemic attack (TIA) (n=1) and transient quadriplegia (n=1). Minor complications were recorded in 143/477 (30%): chest pain 86/143 (60%) and dysphagia 29/143 (20%). During a mean follow-up period of 14 (8-36) months, haemoptysis recurrence was observed in 42/110 cases (38%) of cystic fibrosis and in 77/367 cases of other diseases (21%).

CONCLUSIONS

BAE and NBAE are effective and safe for acute treatment of haemoptysis, with low recurrence and complication rates. Interventional radiologist experience is crucial to the successful haemoptysis control and preventing complications.

A friend to the airways: a review of the emerging clinical importance of the bronchial arterial circulation

Lungs receive the bulk of their blood supply through the pulmonary arteries. The bronchial arteries, on the other hand, vascularize the bronchi and their surroundings. These two arteries anastomose near the alveolar ducts. Contrary to the pulmonary circulation which is fairly well studied, the bronchial arteries have been appreciated more by their absence, and in some cases, by an interruption in the pulmonary arterial flow. Therefore, a more accurate anatomical and functional knowledge of these atherosclerosis-resistant vessels is needed to help surgeons and clinicians to avoid iatrogenic injuries during pulmonary interventions. In this review, we have revisited the anatomy and pathophysiology of the bronchial arteries in humans, considering the recent advances in imaging techniques. We have also elaborated on the known clinical applications of these arteries in both the pathogenesis and management of common pulmonary conditions.

Inhaled chemotherapy in lung cancer: future concept of nanomedicine

Regional chemotherapy was first used for lung cancer 30 years ago. Since then, new methods of drug delivery and pharmaceuticals have been investigated in vitro, and in animals and humans. An extensive review of drug delivery systems, pharmaceuticals, patient monitoring, methods of enhancing inhaled drug deposition, safety and efficacy, and also additional applications of inhaled chemotherapy and its advantages and disadvantages are presented. Regional chemotherapy to the lung parenchyma for lung cancer is feasible and efficient. Safety depends on the chemotherapy agent delivered to the lungs and is dose-dependent and time-dependent. Further evaluation is needed to provide data regarding early lung cancer stages, and whether regional chemotherapy can be used as neoadjuvant or adjuvant treatment. Finally, inhaled chemotherapy could one day be administered at home with fewer systemic adverse effects.

[Clinical experiences of bronchopleural fistula-related fatal hemoptysis after the resection of lung cancer: a report of 7 cases]

背景与目的

大咯血是肺癌术后少见但严重的并发症。本研究旨在探讨致死性大咯血的发生机制、危险因素、先兆症状及预防和治疗措施。

方法

2007年4月-2011年5月四川大学华西医院共行肺癌手术1, 737例，围手术期死亡20例，其中死于大咯血7例，复习7例患者的临床资料并结合文献进行分析。

结果

大咯血是肺癌术后第2位死亡原因。7例中6例直接死于大咯血，1例因大咯血行二次手术，最终死于肺部感染、呼吸衰竭。4例发生过先兆出血症状。4年大咯血发生率为0.4%（7/1, 737）。

结论

支气管胸膜瘘引起的支气管血管瘘是大咯血发生的机制，糖尿病为高危因素，早期诊断、早期外科治疗支气管胸膜瘘或支气管血管瘘可避免大咯血死亡的发生。

Bronchial artery arising from the left vertebral artery: case report and review of the literature

Knowledge of bronchial artery anatomy, including the possible locations of anomalous origin, is essential for complete catheter directed embolization for massive hemoptysis. Undetected anomalous bronchial arteries can be a source of failed bronchial artery embolization. We report a case of a common trunk bronchial artery arising from the left vertebral artery and review standard and variant bronchial artery anatomy.

Lung and vascular function during chronic severe pulmonary ischemia

Bronchial vascular angiogenesis takes place in a variety of lung inflammatory conditions such as asthma, cystic fibrosis, lung cancer, and chronic pulmonary thromboembolic disease. However, it is unclear whether neovascularization is predominantly appropriate and preserves lung tissue or whether it contributes further to lung pathology through edema formation and inflammation. In the present study we examined airway and lung parenchymal function 14 days after left pulmonary artery ligation. In rats as well as higher mammals, severe pulmonary ischemia results in bronchial vascular proliferation. Using labeled microspheres, we demonstrated an 18-fold increase in systemic blood flow to the ischemic left lung. Additionally, vascular remodeling extended to the tracheal venules, which showed an average 28% increase in venular diameter. Despite this increase in vascularity, airways resistance was not altered nor was methacholine responsiveness. Since these measurements include the entire lung, we suggest that the normal right lung, which represented 78% of the total lung, obscured the ability to detect a change. When functional indexes such as diffusing capacity, in situ lung volume, and vascular permeability of the left lung could be separated from right lung, significant changes were observed. Thus when comparing average left lung values of rats 14 days after left pulmonary artery ligation to left lungs of rats undergoing sham surgery, diffusing capacity of the left lung decreased by 72%, left lung volume decreased by 38%, and the vascular permeability to protein increased by 58%. No significant differences in inflammatory cell recruitment were observed, suggesting that acute ischemic inflammation had resolved. We conclude that despite the preservation of lung tissue, the proliferating bronchial neovasculature may contribute to a sustained decrement in pulmonary function.

Bronchial blood supply after lung transplantation without bronchial artery revascularization

PURPOSE OF REVIEW

This review discusses how the bronchial artery circulation is interrupted following lung transplantation and what may be the long-term complications of compromising systemic blood flow to allograft airways.

RECENT FINDINGS

Preclinical and clinical studies have shown that the loss of airway microcirculations is highly associated with the development of airway hypoxia and an increased susceptibility to chronic rejection.

SUMMARY

The bronchial artery circulation has been highly conserved through evolution. Current evidence suggests that the failure to routinely perform bronchial artery revascularization at the time of lung transplantation may predispose patients to develop the bronchiolitis obliterans syndrome.

The role of the bronchial microvasculature in the airway remodelling in asthma and COPD

In recent years, there has been increased interest in the vascular component of airway remodelling in chronic bronchial inflammation, such as asthma and COPD, and in its role in the progression of disease. In particular, the bronchial mucosa in asthmatics is more vascularised, showing a higher number and dimension of vessels and vascular area. Recently, insight has been obtained regarding the pivotal role of vascular endothelial growth factor (VEGF) in promoting vascular remodelling and angiogenesis. Many studies, conducted on biopsies, induced sputum or BAL, have shown the involvement of VEGF and its receptors in the vascular remodelling processes. Presumably, the vascular component of airway remodelling is a complex multi-step phenomenon involving several mediators. Among the common asthma and COPD medications, only inhaled corticosteroids have demonstrated a real ability to reverse all aspects of vascular remodelling. The aim of this review was to analyze the morphological aspects of the vascular component of airway remodelling and the possible mechanisms involved in asthma and COPD. We also focused on the functional and therapeutic implications of the bronchial microvascular changes in asthma and COPD.

Aberrant right bronchial artery originating from right coronary artery - MDCT angiography findings

Aberrant bronchial arteries are rarely seen and may originate from various vascular structures. In our case, a 48-year-old man with recurrent chest pain underwent multidetector CT (MDCT) coronary angiography. MDCT images demonstrated an aberrant right bronchial artery originating from the right coronary artery. To our knowledge, this is the first case report of an aberrant right bronchial artery originating from the right coronary artery.

Lung transplant airway hypoxia: a diathesis to fibrosis?

RATIONALE

Chronic rejection, manifested pathologically as airway fibrosis, is the major problem limiting long-term survival in lung transplant recipients. Airway hypoxia and ischemia, resulting from a failure to restore the bronchial artery (BA) circulation at the time of transplantation, may predispose patients to chronic rejection. To address this possibility, clinical information is needed describing the status of lung perfusion and airway oxygenation after transplantation.

OBJECTIVES

To determine the relative pulmonary arterial blood flow, airway tissue oxygenation and BA anatomy in the transplanted lung was compared with the contralateral native lung in lung allograft recipients.

METHODS

Routine perfusion scans were evaluated at 3 and 12 months after transplantation in 15 single transplant recipients. Next, airway tissue oximetry was performed in 12 patients during surveillance bronchoscopies in the first year after transplant and in 4 control subjects. Finally, computed tomography (CT)-angiography studies on 11 recipients were reconstructed to evaluate the post-transplant anatomy of the BAs.

MEASUREMENTS AND MAIN RESULTS

By 3 months after transplantation, deoxygenated pulmonary arterial blood is shunted away from the native lung to the transplanted lung. In the first year, healthy lung transplant recipients exhibit significant airway hypoxia distal to the graft anastomosis. CT-angiography studies demonstrate that BAs are abbreviated, generally stopping at or before the anastomosis, in transplant airways.

CONCLUSIONS

Despite pulmonary artery blood being shunted to transplanted lungs after transplantation, grafts are hypoxic compared with both native (diseased) and control airways. Airway hypoxia may be due to the lack of radiologically demonstrable BAs after lung transplantation.

Does the bronchial circulation contribute to congestion in heart failure?

Pulmonary congestion is a hallmark feature of heart failure and is a major reason for hospital admissions in this patient population. Heart failure patients often demonstrate restrictive and obstructive pulmonary function abnormalities; however, the mechanisms of these changes remain controversial. It has been suggested that the bronchial circulation may play an important role in the development of these pulmonary abnormalities and in the symptoms associated with pulmonary congestion. Congestion may occur in the bronchial circulation from either a marked increase in flow or an increase in blood volume but with a reduction in flow due to high cardiac filling pressures and high pulmonary vascular pressures (a stasis like condition). Either may lead to thickened bronchial mucosal and submucosal tissues and reduced airway compliance resulting in airway obstruction and restriction and a lack of airway distensibility. These structural changes may contribute to "cardiac asthma" and dyspnea, characteristic features common in HF patients. Thus the bronchial circulation may be a potential target for therapeutic interventions. The aim of this paper is to review factors governing the control of the bronchial circulation, how bronchial vascular conductance may change with HF and to pose arguments, both supporting and in opposition to the bronchial circulation contributing to congestion and altered pulmonary function in HF. We ultimately hypothesize that the engorgement of the bronchial circulatory bed may play a role in pulmonary function abnormalities that occur in HF patients and contribute to symptoms such as orthopnea and exertional dyspnea.

Effect of ablated bronchial blood flow on survival rate and pulmonary function after burn and smoke inhalation in sheep

The bronchial circulation plays a significant role in the pathophysiological changes of burn and smoke-inhalation injury. Bronchial blood flow markedly increases immediately after inhalational injury. This study examines whether the ablation of the bronchial artery attenuates pathophysiological changes and improves survival after burn and smoke-inhalational injury in an ovine model. Acute lung injury was induced by 40% total body surface-area third-degree cutaneous burn and cotton smoke inhalation (48 breaths of cotton smoke, <40 degrees C) under deep anaesthesia. Twelve adult female sheep were divided into two groups: (1) sham (injured, non-ablated bronchial artery, n=6); (2) ablation (injured, ablated bronchial artery, n=6). Ablation of the bronchial artery was performed 72 h before the injury. The experiment was continued for 96 h. Burn and smoke-inhalation injury significantly increased regional blood flow in the bronchi. Ablation of the bronchial artery significantly reduced acute regional blood flow increases in the proximal and distal bronchi. All animals in the ablation group survived to 96 h. Four of these were successfully weaned off the ventilator. Three animals of the sham group met standardised euthanasia criteria at 60 h, while another met the criteria at 78 h. The lung wet-to-dry weight ratio, histology score and myeloperoxidase (MPO) activity were significantly increased by the insult, but ablation of the bronchial artery attenuated these changes. Burn and smoke-inhalation injury induced a significant increase in bronchial blood flow and accelerated airway obstruction, pulmonary vascular changes, pulmonary oedema and pulmonary dysfunction. Ablated bronchial circulation attenuated these pathophysiological changes.

Exercise-related change in airway blood flow in humans: relationship to changes in cardiac output and ventilation

This study examined the relationship between airway blood flow (Q(aw)), ventilation (V(E)) and cardiac output (Q(tot)) during exercise in healthy humans (n=12, mean age 34+/-11 yr). Q(aw) was estimated from the uptake of the soluble gas dimethyl ether while V(E) and Q(tot) were measured using open circuit spirometry. Measurements were made prior to and during exercise at 34+/-5 W (Load 1) and 68+/-10 W (Load 2) and following the cessation of exercise (recovery). Q(aw) increased in a stepwise fashion (P<0.05) from rest (52.8+/-19.5 microl min(-1) ml(-1)) to exercise at Load 1 (67.0+/-20.3 microl min(-1) ml(-1)) and Load 2 (84.0+/-22.9 microl min(-1) ml(-1)) before returning to pre-exercise levels in recovery (51.7+/-13.2 microl min(-1) ml(-1)). Q(aw) was positively correlated with both Q(tot) (r=0.58, P<0.01) and V(E) (r=0.50, P<0.01). These results demonstrate that the increase in Q(aw) is linked to an exercise related increase in both Q(tot) and V(E) and may be necessary to prevent excessive airway cooling and drying.

Bronchial circulation angiogenesis in the rat quantified with SPECT and micro-CT

INTRODUCTION

As pulmonary artery obstruction results in proliferation of the bronchial circulation in a variety of species, we investigated this angiogenic response using single photon emission computed tomography (SPECT) and micro-CT.

MATERIALS AND METHODS

After surgical ligation of the left pulmonary artery of rats, they were imaged at 10, 20, or 40 days post-ligation. Before imaging, technetium-labeled macroaggregated albumin ((99m)Tc MAA) was injected into the aortic arch (IA) labeling the systemic circulation. SPECT/micro-CT imaging was performed, the image volumes were registered, and activity in the left lung via the bronchial circulation was used as a marker of bronchial blood flow. To calibrate and to verify successful ligation, (99m)Tc MAA was subsequently injected into the left femoral vein (IV), resulting in accumulation within the pulmonary circulation. The rats were reimaged, and the ratio of the IA to the IV measurements reflected the fraction of cardiac output (CO) to the left lung via the bronchial circulation. Control and sham-operated rats were studied similarly.

RESULTS

The left lung bronchial circulation of the control group was 2.5% of CO. The sham-operated rats showed no significant difference from the control. However, 20 and 40 days post-ligation, the bronchial circulation blood flow had increased to 7.9 and 13.9%, respectively, of CO. Excised lungs examined after barium filling of the systemic vasculature confirmed neovascularization as evidenced by tortuous vessels arising from the mediastinum and bronchial circulation.

CONCLUSION

Thus, we conclude that SPECT/micro-CT imaging is a valuable methodology for monitoring angiogenesis in the lung and, potentially, for evaluating the effects of pro- or anti-angiogenic treatments using a similar approach.

Lung ischemia-reperfusion injury: implications of oxidative stress and platelet-arteriolar wall interactions

Pulmonary ischemia-reperfusion (IR) injury may result from trauma, atherosclerosis, pulmonary embolism, pulmonary thrombosis and surgical procedures such as cardiopulmonary bypass and lung transplantation. IR injury induces oxidative stress characterized by formation of reactive oxygen (ROS) and reactive nitrogen species (RNS). Nitric oxide (NO) overproduction via inducible nitric oxide synthase (iNOS) is an important component in the pathogenesis of IR. Reaction of NO with ROS forms RNS as secondary reactive products, which cause platelet activation and upregulation of adhesion molecules. This mechanism of injury is particularly important during pulmonary IR with increased iNOS activity in the presence of oxidative stress. Platelet-endothelial interactions may play an important role in causing pulmonary arteriolar vasoconstriction and post-ischemic alveolar hypoperfusion. This review discusses the relationship between ROS, RNS, P-selectin, and platelet-arteriolar wall interactions and proposes a hypothesis for their role in microvascular responses during pulmonary IR.

Massive pulmonary artery thrombosis with haemoptysis in adults with Eisenmenger's syndrome: a clinical dilemma

Although the frequency of haemoptysis in Eisenmenger's syndrome is well recognised, the high prevalence of pulmonary artery thrombus has been newly appreciated through the growing use of non-invasive imaging. Three patients with Eisenmenger's syndrome with haemoptysis are reported who underwent computed tomography pulmonary angiography and cardiovascular magnetic resonance. Each patient was found to have aneurysmal dilatation of the right pulmonary artery with large laminar thrombus. These cases illustrate a rising clinical problem in this special population-that is, how to treat and prevent large pulmonary artery thrombosis in the setting of haemoptysis. The authors discuss their approach to these cases and the known literature.

Pulmonary drug delivery. Part I: physiological factors affecting therapeutic effectiveness of aerosolized medications

As the end organ for the treatment of local diseases or as the route of administration for systemic therapies, the lung is a very attractive target for drug delivery. It provides direct access to disease in the treatment of respiratory diseases, while providing an enormous surface area and a relatively low enzymatic, controlled environment for systemic absorption of medications. As a major port of entry, the lung has evolved to prevent the invasion of unwanted airborne particles from entering into the body. Airway geometry, humidity, mucociliary clearance and alveolar macrophages play a vital role in maintaining the sterility of the lung and consequently are barriers to the therapeutic effectiveness of inhaled medications. In addition, a drug's efficacy may be affected by where in the respiratory tract it is deposited, its delivered dose and the disease it may be trying to treat.