Post splenectomy related pulmonary hypertension

Splenectomy predisposes patients to a slew of infectious and non-infectious complications including pulmonary vascular disease. Patients are at increased risk for venous thromboembolic events due to various mechanisms that may lead to chronic thromboembolic pulmonary hypertension (CTEPH). The development of CTEPH and pulmonary vasculopathy after splenectomy involves complex pathophysiologic mechanisms, some of which remain unclear. This review attempts to congregate the current evidence behind our understanding about the etio-pathogenesis of pulmonary vascular disease related to splenectomy and highlight the controversies that surround its management.

Autotaxin and lysophosphatidic acid signalling in lung pathophysiology

Autotaxin (ATX or ENPP2) is a secreted glycoprotein widely present in biological fluids. ATX primarily functions as a plasma lysophospholipase D and is largely responsible for the bulk of lysophosphatidic acid (LPA) production in the plasma and at inflamed and/or malignant sites. LPA is a phospholipid mediator produced in various conditions both in cells and in biological fluids, and it evokes growth-factor-like responses, including cell growth, survival, differentiation and motility, in almost all cell types. The large variety of LPA effector functions is attributed to at least six G-protein coupled LPA receptors (LPARs) with overlapping specificities and widespread distribution. Increased ATX/LPA/LPAR levels have been detected in a large variety of cancers and transformed cell lines, as well as in non-malignant inflamed tissues, suggesting a possible involvement of ATX in chronic inflammatory disorders and cancer. In this review, we focus exclusively on the role of the ATX/LPA axis in pulmonary pathophysiology, analysing the effects of ATX/LPA on pulmonary cells and leukocytes in vitro and in the context of pulmonary pathophysiological situations in vivo and in human diseases.

Caveolae, caveolin-1 and cavin-1: Emerging roles in pulmonary hypertension

Caveolae are flask-shaped invaginations of cell membrane that play a significant structural and functional role. Caveolae harbor a variety of signaling molecules and serve to receive, concentrate and transmit extracellular signals across the membrane. Caveolins are the main structural proteins residing in the caveolae. Caveolins and another category of newly identified caveolae regulatory proteins, named cavins, are not only responsible for caveolae formation, but also interact with signaling complexes in the caveolae and regulate transmission of signals across the membrane. In the lung, two of the three caveolin isoforms, i.e., cav-1 and -2, are expressed ubiquitously. Cavin protein family is composed of four proteins, named cavin-1 (or PTRF for polymerase I and transcript release factor), cavin-2 (or SDPR for serum deprivation protein response), cavin-3 (or SRBC for sdr-related gene product that binds to-c-kinase) and cavin-4 (or MURC for muscle restricted coiled-coiled protein or cavin-4). All the caveolin and cavin proteins are essential regulators for caveolae dynamics. Recently, emerging evidence suggest that caveolae and its associated proteins play crucial roles in development and progression of pulmonary hypertension. The focus of this review is to outline and discuss the contrast in alteration of cav-1 (cav-1),-2 and cavin-1 (PTRF) expression and downstream signaling mechanisms between human and experimental models of pulmonary hypertension.

Pulmonary complications of transcatheter arterial chemoembolization for hepatocellular carcinoma

Transcatheter arterial chemoembolization (TACE) is an effective palliative intervention that is widely accepted for the management of hepatocellular carcinoma (HCC). Post-TACE pulmonary complications resulting in acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are rare events. Pulmonary complications after TACE are thought to be related to chemical injury subsequent to the migration of the infused ethiodized oil or chemotherapeutic agent to the lung vasculature, facilitated by arteriovenous (AV) shunts within the hyper-vascular HCC. We review herein the literature on pulmonary complications related to TACE for HCC. Post-TACE pulmonary complications have included pulmonary oil embolism, interstitial pneumonitis, chemical pneumonitis, ALI, ARDS, lipoid pneumonia, acute eosinophilic and neutrophilic pneumonia, bilious pleuritis, pulmonary abscess, pulmonary tumor embolism, and possibly pulmonary metastasis with HCC. The risk factors associated with post-TACE pulmonary complications identified in the literature include large hyper-vascular HCC with AV shunts, large-volume Lipiodol infusion, and embolization via the right inferior phrenic artery. However, the absence of known risk factors is not a guarantee against serious complications. An astute awareness of the potential post-TACE pulmonary complications should expedite appropriate therapeutic interventions and increase potential for early recovery.

Advance of antioxidants in asthma treatment

Asthma is an allergic disease, characterized as a recurrent airflow limitation, airway hyperreactivity, and chronic inflammation, involving a variety of cells and cytokines. Reactive oxygen species have been proven to play an important role in asthma. The pathogenesis of oxidative stress in asthma involves an imbalance between oxidant and antioxidant systems that is caused by environment pollutants or endogenous reactive oxygen species from inflammation cells. There is growing evidence that antioxidant treatments that include vitamins and food supplements have been shown to ameliorate this oxidative stress while improving the symptoms and decreasing the severity of asthma. In this review, we summarize recent studies that are related to the mechanisms and biomarkers of oxidative stress, antioxidant treatments in asthma.

Effects of methyl palmitate and lutein on LPS-induced acute lung injury in rats

AIM: To investigate the effects of methyl palmitate and lutein on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and explore the possible mechanisms.

METHODS: Male Sprague-Dawley rats were divided into 4 groups: (1) control; (2) LPS; (3) Methyl palmitate; and (4) Lutein groups. Methyl palmitate (300 mg/kg, ip) was administered 3 times per week on alternating days while lutein (100 mg/kg, oral) was given once daily. After 1 wk of vehicle/methyl palmitate/lutein treatment, ALI was induced by a single dose of LPS (7.5 mg/kg, iv). After 24 h of LPS injection, animals were sacrificed then biochemical parameters and histopathology were assessed.

RESULTS: Treatment with methyl palmitate attenuated ALI, as it significantly decreased the lung wet/dry weight (W/D) ratio, the accumulation of the inflammatory cells in the bronchoalveolar lavage fluid (BALF) and histopathological damage. However, methyl palmitate failed to decrease lactate dehydrogenase (LDH) activity in BALF. On the other hand, lutein treatment produced significant anti-inflammatory effects as revealed by significant decrease in accumulation of inflammatory cells in lung, LDH level in BALF and histopathological damage. Methyl palmitate and lutein significantly increased superoxide dismutase (SOD) and reduced glutathione (GSH) activities with significant decrease in the lung malondialdehyde (MDA) content. Importantly, methyl palmitate and lutein decreased the level of the inflammatory cytokine tumor necrosis factor-α (TNF-α) in the lung. Lutein also reduced LPS-mediated overproduction of pulmonary nitrite/nitrate (NO₂^-/NO₃^-), which was not affected by methyl palmitate pretreatment.

CONCLUSION: These results demonstrate the potent protective effects of both methyl palmitate and lutein against LPS-induced ALI in rats. These effects can be attributed to potent antioxidant activities of these agents, which suppress inflammatory cell infiltration and regulated cytokine effects.

Lung microbiome in healthy and diseased individuals

The data on quantitative and qualitative microbial composition of the respiratory tract of healthy individuals revealed significant differences when compared with the microbiota of patients suffering from respiratory diseases. Possible etiological role of microbiota in pulmonary diseases as well as drug resistance development is of profound interest nowadays. Numerous studies have provided evidence confirming the relationship between gut microbiome and those of lungs. This relationship could explain how changes in the microbial communities in one organ may lead to pathological changes in the other. Till date, some progress has been made in the study of the biological properties of probiotic bacteria, considering their modulating effect on inflammatory immune response. The use of probiotics which exhibits an immunomodulatory potential looks promising.

Effect of oxidative stress on development of silicosis

AIM: To investigate the changes of oxidative stress indicators in the serum of silicosis patients and explore the mechanism of silicosis development.

METHODS: Two hundred workers who were exposed to silica dust for more than one year were recruited as dust-exposed group, 100 non-dust-exposed subjects served as control group, 32 patients with suspected 0⁺ silicosis as observation group, and 130 silicosis patients were taken as the silicosis group. Indicators of oxidative stress, including superoxide dismutase (SOD), nitric oxide (NO), serum glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), nitric oxide synthase (NOS), and lipid malondialdehyde (MDA), were determined in all the groups.

RESULTS: Compared with the control group, NO and GSH-Px in dust-exposed group and silicosis group increased, and SOD decreased significantly (81.162 ± 35.176, 270.469 ± 39.228 and 68.209 ± 21.528, respectively, P = 0.004, P = 0.002, P = 0.005). Compared with the control and dust-exposed group, T-AOC, NOS and MDA in silicosis group increased significantly (13.048 ± 4.153, 36.201 ± 7.782 and 5.054 ± 1.204, respectively, P = 0.018, P = 0.022, P = 0.011). Compared with dust-exposed group, GSH-Px in the silicosis group increased significantly (270.469 ± 39.228, P = 0.002). GSH-Px in phase III silicosis was significantly higher than in phase I silicosis (290.750 ± 39.129, P = 0.021). Pearson correlation analysis showed that serum GSH-Px was positively correlated with silicosis staging, length of dust exposure and type of occupation (47.109 ± 8.015, P = 0.001).

CONCLUSION: The imbalance of oxidative and anti-oxidation system is associated with the development of silicosis. The surveillance of oxidative stress indicators will benefit the prognosis of silicosis patients.

Prognostic scoring systems for clinical course and survival in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and rapidly fatal among idiopathic interstitial pneumonias. Its clinical course is variable. A significant fraction of the population of patients display a slow disease course and can remain stable for years, while other patients show a rapid progressive course and may die within few months from diagnosis. For these reasons estimating prognosis of IPF patients is extremely difficult and has important clinical repercussions on optimal patients management including patients referral for lung transplantation. Several studies have tried to address this key point in the course of the two last decades analyzing different clinical, functional, radiological and biological variables. The purpose of this review is to assess relevant studies published on this subject and to examine the variety of prognostic predictors proposed along with staging systems.

Treatment of central sleep apnea in patients with heart failure: Now and future

Heart failure (HF) is known to be associated with sleep-disordered breathing (SDB). In addition to disturbing patients’ sleep, SDB is also associated with a deterioration in the cardiac function and an increased mortality and morbidity. Central sleep apnea (CSA), typically characterized by Cheyne-Stokes breathing (CSB), is increasingly found in patients with HF compared to the general population. An important pathogenetic factor of CSA seen in HF patients is an instability in the control of the respiratory system, characterized by both hypocapnia and increased chemosensitivity. Sympathetic overactivation, pulmonary congestion and increased chemosensitivity associated with HF stimulate the pulmonary vagal irritant receptor, resulting in chronic hyperventilation and hypocapnia. Additionally, the repetitive apnea and arousal cycles induce cyclic sympathetic activation, which may worsen the cardiac prognosis. Correcting CSB may improve both patient’s quality of life and HF syndrome itself. However, a treatment for HF in patients also experiencing CSA is yet to be found. In fact, conflicting results from numerous clinical studies investigating sleep apnea with HF guide to a troubling question, that is whether (or not) sleep apnea should be treated in patients with HF? This editorial attempts to both collect the current evidence about randomized control trials investigating CSA in patients with HF and highlight the effect of specific CSA treatments on cardiovascular endpoints.

Mechanical circulatory support in lung transplantation: Cardiopulmonary bypass, extracorporeal life support, and ex-vivo lung perfusion

Lung transplant is the standard of care for patients with end-stage lung disease refractory to medical management. There is currently a critical organ shortage for lung transplantation with only 17% of offered organs being transplanted. Of those patients receiving a lung transplant, up to 25% will develop primary graft dysfunction, which is associated with an 8-fold increase in 30-d mortality. There are numerous mechanical lung assistance modalities that may be employed to help combat these challenges. We will discuss the use of mechanical lung assistance during lung transplantation, as a bridge to transplant, as a treatment for primary graft dysfunction, and finally as a means to remodel and evaluate organs deemed unsuitable for transplant, thus increasing the donor pool, improving survival to transplant, and improving overall patient survival.

Update on the use of portable monitoring system for the diagnosis of sleep apnea in specific population

The prevalence and severity of obstructive sleep apnea (OSA) is higher in specific population: children, elderly, obese and patients with pulmonary and cardiovascular diseases, compared to the general population. OSA is associated with greater morbidity and mortality in these patients. Although full-night polysomnography is still the gold standard diagnostic sleep study for OSA, it is a time consuming, expensive and technically demanding exam. Over the last few years, there is growing evidence on the use of portable monitors (PM) as an alternative for the diagnosis of OSA. These devices were developed specially for sleep evaluation at home, at a familiar environment, with easy self-application of monitoring, unattended. The use of PM is stablished for populations with high pre-test probability of OSA. However, there is a lack of studies on the use of PM in age extremes and patients with comorbidities. The purpose of this review is to present the studies that evaluated the use of PM in specific population, as well as to describe the advantages, limitations and applications of these devices in this particular group of patients. Although the total loss rate of recordings is variable in different studies, the agreement with full-night polysomnography justifies the use of PM in this population.

New therapies for chronic obstructive pulmonary disease, lung regeneration

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow limitations that are not fully reversible and is a major cause of chronic morbidity and mortality worldwide. Although there has been extensive research examining the molecular mechanisms underlying the development of COPD, there is no proven clinically effective treatment for promoting recovery from established COPD. At present, regeneration is the only hope for a cure in patients with COPD. In this article, we review current treatments for COPD, focusing particularly on recent advances in lung regeneration based on two major approaches: regeneration-promoting agents and cell therapy. Retinoic acids are the major focus among regeneration-promoting agents, while mesenchymal stem cells are the main topic in the field of cell-based therapy. This article aims to provide valuable information for developing new therapies for COPD.

Lung cancer screening: Should we be excluding people with previous malignancy?

The National Lung Screening Trial (NLST) was a large, randomized, controlled study showing a 20% reduction of lung cancer mortality and 7% reduction of all cause mortality using annual low dose computed tomography (LDCT) in a high risk population. NLST excluded people with a previous history of cancer treatment within the past 5 years and all people with a history lung cancer. The aim of this work is to review how lung cancer screening trials addressed the confounding effect of previous malignancy. We also review the subsequent recommendations by the United States Preventative Task Force Services, multiple professional societies and the Center for Medicaid and Medicare Services which defer either to NLST criteria or, clinician judgment or refrain from asserting any recommendation on the topic, respectively. Implications of lung cancer screening in the setting of previous malignancies, specifically lung, head and neck, esophageal, gastric, breast, colorectal cancer and lymphoma are also discussed. With lung cancer screening, an antecedent malignancy introduces the possibility of discovering metastasis as well as lung cancer. In some circumstances diagnosis and treatment of oligometastatic disease may confer a survival benefit. The survival benefit of treating either lung cancer or oligometastatic disease as result of lung cancer screening has yet to be determined. Further studies are needed to determine the role of lung cancer screening in the setting of previous malignancy.

Historical transition of management of sarcoidosis

Sarcoidosis is a systemic granulomatous disease of undetermined etiology, and it primarily affects the lungs and lymphatic system but may involve other organs. Recently, there have been several new insights in Japanese patients. The frequency of cardiac, ocular, and cutaneous sarcoidosis has increased in Japan, whereas, the proportion of patients with bilateral hilar lymphadenopathy decreased from 1960 to 2004. Propionibacterium acnes (P. acnes) has been studied extensively as one of the causative microorganism for granuloma formation, particularly in Japan. P. acnes-specific monoclonal antibodies are useful for diagnosing sarcoidosis. The potential association between smoking and sarcoidosis has been evaluated in a Japanese study, which found a higher prevalence of sarcoidosis among young smokers than that in previous reports. Recently, ¹⁸F-fluorodeoxyglucose positron-emission tomography, which permits visualization of activated inflammation, and endobronchial ultrasonography-guided transbronchial needle aspiration have been increasingly used to diagnose sarcoidosis. Cardiac sarcoidosis is found to be the main cause of death in Japan. The 2006 revised Japanese guidelines for diagnosing cardiac sarcoidosis are useful, particularly for subclinical cardiac sarcoidosis patients. Further studies and international communication and evaluation are needed to determine the causes of sarcoidosis, identify the risk factors for progressive disease, and develop new and effective treatments.

Sleep apnea and fatty liver disease: The growing link and management issues

Obstructive sleep apnea (OSA) is associated with metabolic, cardiovascular and neuropsychological disorders, with substantial morbidity and economic costs. OSA has been estimated to affect 4%-11% of the population, depending on age. Obesity is a significant risk factor for OSA. Non alcoholic fatty liver disease (NAFLD) has emerged as an integral component of the metabolic syndrome, with insulin resistance as the central pathogenic feature. Estimates based on imaging and autopsy studies suggest that about 20%-30% of adults in the United States and other Western countries have NAFLD. Evidence now suggests that NAFLD is independently correlated to insulin resistance regardless of adiposity. Some authors have suggested that OSA may be another contributor to NAFLD development. In complex diseases, several or many different genes interact with environmental factors in determining disease presence or its phenotype. Individual genes only have a small effect on disease risk and can therefore be very difficult to identify. The genetic and hormonal determinants of OSA and NAFLD have received little attention. A wide variety of intermediate phenotypes and genes are involved in OSA and NAFLD which makes this syndrome genetically complex. Various adipokines, the most important of which are leptin, adiponectin, tumor necrosis factor-alpha, resistin and interleukin-6, have a key role in NAFLD and OSA. Some studies have suggested that oxidative stress may also contribute to the development of NAFLD and OSA. Lifestyle intervention, insulin sensitizer drugs and bariatric surgery aim to improve metabolic syndrome, OSA and NAFLD but need further investigation.

Respiratory physiotherapy in gastroesophageal reflux disease: A review article

Gastroesophageal reflux disease (GERD) is a frequent disorder which is expensive to diagnose and treat. Initiating therapy with empiric trial of proton-pump inhibitor is a well established strategy; however, symptoms of GERD do often persist regardless of effective medication. Nowadays, increasing interest concerning the efficacy and safety of chronic acid suppression with proton-pump inhibitors (PPIs), prompts a consideration for GERD treatment strategies related to the basic physiology of the lower esophageal sphincter, including modulation of its tone and ending of spontaneous transient lower esophageal sphincter relaxation, which contributes to reflux. Together, the lower esophageal sphincter and the crural diaphragm represent the major antireflux barrier, protecting the esophagus from reflux of gastric content. In order to prevent the need for enduring PPIs therapy or surgical procedures, substitute therapeutics approaches are being researched. Recently, studies have focused on the response of the respiratory muscles to inspiratory muscle training. As a result, inspiratory muscle training has emerged as a potential alternative for treatment of gastroesophageal reflux. The present report reviews the physiologic factors contributing to GERD, and presents the newly developed therapies that can be applied either alone or in association with available efficient GERD therapy.

Relationship between metabolic syndrome and hypercapnia among obese patients with sleep apnea

BACKGROUND

In the obese patient population, some patients have severe obstructive sleep apnea (OSA) with daytime hypoventilation. Such patients are generally identified on the basis of the presence or absence of daytime hypercapnia, and the condition is called obesity hypoventilation syndrome. However, mechanisms for such daytime hypoventilation remain unclear.

AIM

To investigate metabolic syndrome and daytime hypercapnia association based on hypercapnia prevalence in obese OSA patients in a nested case-control study.

METHODS

Consecutive obese patients (body mass index ≥ 30 kg/m²) who underwent polysomnography due to suspected OSA were included. Among them, patients with severe OSA (apnea hypopnea index ≥ 30/h) were divided into two groups according to the presence or absence of hypercapnia during wakefulness (arterial partial pressure of carbon dioxide ≥ or < 45 Torr, respectively). The characteristics and clinical features of these two groups were compared.

RESULTS

Among 97 eligible patients, 25 patients (25.8%) had daytime hypercapnia. There were no significant differences in age, gender, body mass index, apnea-hypopnea index, and Epworth Sleepiness Scale scores between the two groups. However, patients with hypercapnia had a significantly lower arterial partial pressure of oxygen level (75.8 ± 8.2 torr vs 79.9 ± 8.7 torr, P = 0.042) and higher arterial partial pressure of carbon dioxide level (46.6 ± 2.5 torr vs 41.0 ± 2.9 torr, P < 0.001). Additionally, patients with hypercapnia were more likely to have metabolic syndrome (72.0% vs 48.6%, P = 0.043) and a higher metabolic score (the number of satisfied criteria of metabolic syndrome). In multivariate logistic regression analysis, the presence of metabolic syndrome was associated with the presence of hypercapnia (OR = 2.85, 95%CI: 1.04-7.84, P = 0.042).

CONCLUSION

Among obese patients with severe OSA, 26% of patients had hypercapnia during wakefulness. The presence of metabolic syndrome was independently correlated with the presence of daytime hypercapnia.

Diagnosis and treatment of subsegmental pulmonary embolism

Subsegmental pulmonary embolism (SSPE) affects the 4th division and more distal pulmonary arterial branches. SSPE can be isolated or affect multiple subsegments, be symptomatic or incidental (unsuspected) and may or may not be associated with deep vein thrombosis. Symptoms, clinical risk scores and biomarkers are less sensitive for diagnosing SSPE compared to more central pulmonary embolism. The diagnosis is confirmed using radiological imaging, predominately computed tomographic pulmonary angiogram (CTPA) or ventilation/perfusion scanning. The increasing utilization of CTPAs may have resulted in overdiagnosis driven by smaller pulmonary emboli. There is insufficient evidence of improved mortality or reduced venous thromboembolism recurrence with anticoagulation treatment for SSPE however, the major and clinically significant haemorrhage risks are well described. As the resolution of diagnostic imaging has improved, we may be viewing the natural physiological filtering process performed by the lungs that may not require treatment.

Like father, like son: Pulmonary thromboembolism due to inflammatory or hereditary condition? Two case reports

BACKGROUND

Venous thromboembolism, which includes deep venous thrombosis and pulmonary embolism, is a well-known causal disorder with high morbidity and mortality rates. Inherited or acquired conditions affecting components of coagulation and fibrinolysis systems have been linked to venous thromboembolism pathogenesis as they may lead to a pro-inflammatory state in human bodies. Toxoplasmosis is a zoonosis that potentially leads to acute systemic cachectic-inflammatory effects in experimental animal models but is not yet proven in humans. It is known that venous thrombosis can occur during acute inflammatory/infectious diseases, although it is not well established with regard to toxoplasmosis alone.

CASE SUMMARY

A 70-year-old Caucasian man and his 32-year-old son developed general malaise, chills, fever, and myalgia, having established a diagnosis of toxoplasmosis. Twenty days later, they presented dry cough leading to further investigations that revealed an incidental deep venous thrombosis plus pulmonary embolism in them both. Thrombophilia screening showed both patients had a factor V Leiden mutation heterozygosis. Father and son completely recovered without any sequalae after anticoagulant treatment. They have not presented symptom recurrence of either medical disorder during 1 year of follow-up.

CONCLUSION

Toxoplasmosis may enhance the risk of venous thromboembolism in patients showing factor V Leiden mutation heterozygosis.

Is the determination of ctDNA a scientific “spy” that foresees cancer?

Since 1948, circulating tumour DNA (ctDNA) was first identified in human blood. ctDNA is in fact DNA shed by tumour cells from all metastatic tumour locations throughout the whole body, and is thrown into the bloodstream and can then be isolated by a standard blood draw. Using this technique scientists can obtain a wide view of tumour heterogeneity, identify different mechanisms of drug resistance, what is its predominance and the clinical rational of precision cancer medicine become a part of our daily practice. Secondly, early detection of cancer may also contribute to global decrease in cancer mortality.

Pitfalls in spirometry: Clinical relevance

Spirometry is one of the functional tests most used in respiratory medicine to assess lung function in health and disease conditions. Its success is grounded on solid principles of lung mechanics that state that maximal flow on expiration is limited by the physical properties of airways and lung parenchyma. In contrast, on inspiration, flow depends on the force generated by the inspiratory muscles. Reduced expiratory forced flow and volumes usually reflect a deviation from health conditions. Yet due to a complex interplay of different obstructive and restrictive lung diseases within the multiple structural dimensions of the respiratory system, flows and volumes do not always perfectly reflect the impact of the disease on lung function. The present review is intended to shed light on a series of artefacts and biological phenomena that may confound the clinical interpretation of the main spirometric measurements. Among them is thoracic gas compression volume, the volume and time history of the inspiratory manoeuvre that precedes the forced expiration, the effects of heterogeneous distribution of the disease across the respiratory system, and the changes in lung elastic recoil.

Polymyxin B-immobilized fiber columns: A column to breathe new life into the treatment of interstitial lung disease?

Acute exacerbations of idiopathic pulmonary fibrosis (IPF) is a severe respiratory condition with high mortality rate. Direct hemoperfusion with polymyxin B-immobilized fiber columns (PMX-DHP) was originally introduced for the treatment of septic shock. Application of PMX-DHP to the treatment of acute exacerbations of IPF may improve oxygenation and survival of the patients with the disease. In addition to acute exacerbations of IPF, PMX-DHP has been applied to acute respiratory failure from various causes; an amyopathic dermatomyositis patient who developed rapidly progressive interstitial lung disease (ILD) with elevated anti-CADM-140/MDA5 autoantibody and a patient with severe amiodarone pulmonary toxicity. It is also demonstrated that PMX-DHP performed on the first day of steroid pulse therapy may improve the prognosis of patients with rapidly progressive ILDs in a case-control setting. PMX treatment decreases not only various circulating molecules but also inflammatory cells, in particular activated monocytes, producing such mediators. Although the incidence of acute exacerbations of IPF is too low for proper randomization, in order to test the effects of PMX-DHP on the disease, a cohort or case-control analytic study needs to be conducted, preferably from more than one center or research group.

Classical regression equations of spirometric parameters are not applicable for diagnosing spirometric abnormalities in adipotic adults

The prevalence of overweighing and obese adults (defined as “adipotic” adults), has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults. Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory, independent variables such as age (A), standing height (H), body weight (BW), and fat fraction of body mass (F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m² and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for non-adipotic adults, leading to the conclusion that the regression equations for non-adipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.

High-frequency electrical stimulation of cervical vagi reduces airway response to methacholine

AIM: To test whether high-frequency electrical stimulation (HES) of the bilateral cervical vagus nerves reduces the airway responses to methacholine (MCh).

METHODS: Guinea pigs were pretreated with saline (Sal, n = 9) or ovalbumin (Ova, n = 10) aerosol for two weeks (5 min/d, 5 d/wk) and subsequently anesthetized, paralyzed, tracheotomized and artificially ventilated. Both total lung resistance (R_L) and dynamic pulmonary compliance (C_dyn) were recorded. In addition, the effects of vagal low-frequency electrical stimulation (LES, monophasic, 50 Hz) and HES (monophasic and biphasic, 1 and 2.5 kHz) for about 10 s or 2 min on the responses of R_L and C_dyn to MCh aerosol-induced bronchoconstriction were compared in both groups of guinea pigs. In a few guinea pigs, the impact of bivagotomy on the R_L responses to MCh was assessed.

RESULTS: Before MCh challenge, LES, but not HES, significantly increased R_L by about 30% (P < 0.01) and decreased C_dyn by about 20% (P < 0.01) similarly in both groups. MCh aerosol for 2 min elevated R_L and diminished C_dyn more in Ova- than Sal-treated animals (R_L: 313% ± 52% vs 113% ± 17%, P < 0.01; C_dyn: -56% ± 7% vs -21% ± 3%, P < 0.01). During MCh-induced airway constriction, LES further enhanced, but HES decreased R_L and this decrease was greater in Ova- (about 45%) than Sal-treated animals (about 34%, P < 0.01) with little change in cardiovascular activity. On the other hand, LES further reduced whereas HES increased C_dyn more in Ova- (about 20%) than Sal-treated animals (about 13%, P < 0.01). In addition, bivagotomy almost eliminated the R_L and C_dyn responses to MCh.

CONCLUSION: We conclude that vagal HES is able to alleviate the bronchoconstriction induced by MCh in anesthetized guinea pigs, likely via reversible inhibition/blockade of vagal conduction.