Showing papers in "Current Opinion in Pulmonary Medicine in 1999"

Upper extremity deep vein thrombosis

Abstract: Upper extremity deep-vein thrombosis has recently been recognized as being a more common and less benign disease than previously reported It arises generally in the presence of recognizable risk factors, such as central venous catheters and cancer However, as many as 20% of patients present with apparently spontaneous episodes The prevalence of inherited coagulation defects in patients with this disease ranges from 10% to 26% The clinical picture of upper extremity DVT is characterized by pain, edema, and functional impairment, although it may be completely asymptomatic Because the prevalence of this thrombotic disease is less than 50% among symptomatic subjects, objective diagnosis is mandatory prior to instituting an anticoagulant treatment When available, compression ultrasonography (alone or associated with Doppler or color Doppler facilities) should be the preferred initial diagnostic test However, contrast venography may be necessary before anticoagulants are withheld because of negative findings on compression ultrasonography Pulmonary embolism complicates upper extremity deep-vein thrombosis in up to 36% of patients and may even be the presenting manifestation of this disorder Its long-term clinical course is complicated by recurrent thromboembolism and post-thrombotic sequelae Among the therapeutic options advocated for the therapy of upper extremity deep-vein thrombosis, unfractionated or low molecular weight heparin followed by at least 3 months of oral anticoagulants should be regarded as the treatment of choice Thrombolysis and surgical procedures may be indicated in selected cases The prevention of this disease requires the institution of appropriate pharmacologic measures (ie, low-dose unfractionated or low molecular weight heparin or low-dose warfarin) whenever an indwelling central venous catheter is indicated This review suggests that upper extremity deep-vein thrombosis is at least as serious a disease entity as deep-vein thrombosis of the lower extremities

Worldwide epidemiology of chronic obstructive pulmonary disease.

Abstract: Chronic obstructive pulmonary disease (COPD) continues to cause a heavy health and economic burden around the world. Recent studies have added evidence to the etiologic role of known and suspected risk factors for lung function decline and COPD, including smoking, occupational exposures, air pollution, airway hyperresponsiveness, and certain genetic variations. Among most populations, COPD prevalence and mortality are still increasing and will likely continue to rise in response to increases in smoking, particularly by women and adolescents. Resources aimed at smoking cessation and prevention and the early detection of COPD will be of the most benefit in our continuing efforts against this important cause of morbidity and mortality.

The role of cigarette smoke in the pathogenesis of asthma and as a trigger for acute symptoms.

Abstract: Although it has been long believed that cigarette smoke is injurious to the lower respiratory tract, the exact early mechanisms and early events responsible for this injury remain unclear. Maternal smoking, particularly in utero, is clearly associated with an increased risk for the later development of childhood atopy and asthma. Smoking is known to increase the inflammatory burden of the lower respiratory tract through a number of related but separate mechanisms. These include the recruitment of increased numbers of inflammatory cells, alteration in cell subtypes, enhancement of some cellular functions, and proinflammatory mediator release. In addition, cigarette smoking in vitro and in animal models appears to promote neurogenic inflammation, increase oxidative stress and lead to the elevation of cysteinyl leukotrienes, all of which could potentially lead to an amplification of the airway inflammation already present in asthmatics. Greater and more consistent effort must be given to encourage the young asthmatic not to smoke. In addition, greater effort must be spent on smoking cessation, especially in pregnant women and young asthmatics.

Useful tests on the pleural fluid in the management of patients with pleural effusions.

Abstract: Examination of the pleural fluid is useful in establishing the etiology of a pleural effusion. Transudative pleural effusions can be differentiated from exudative pleural effusions by measuring the levels of protein and lactic acid dehydrogenase in the pleural fluid and serum. If a patient clinically appears to have a transudative pleural effusion, but the pleural fluid meets exudative criteria, demonstration that the albumin levels is more than 1.2 gm/dl higher in the serum than in the pleural fluid provides evidence that the effusion is transudative. The gross appearance of the pleural fluid should always be noted. Other tests that routinely should be obtained on exudative pleural fluids are Gram stain and cultures, cell counts and differential, glucose, amylase, lactic acid dehydrogenase, cytology, and a marker for tuberculous pleuritis. The diagnosis of tuberculous pleuritis is strongly suggested by a pleural fluid adenosine deaminase level above 45 IU/L or a gamma interferon level above 3.7 U/ml.

Pulmonary involvement in Behçet disease.

Abstract: Pulmonary artery aneurysms varying in size and number continue to be the principal feature of pulmonary involvement in Behcet disease (BD). Pulmonary aneurysms have been reported to be associated with cardiac thromboses, mainly in the right heart. Bronchiolitis obliterans organizing pneumonia has also been seen in the setting of pulmonary artery aneurysms. Aneurysms of the aortic arch and subclavian artery are rarely recognized thoracic manifestations of BD. Noninvasive imaging techniques, such as helical computed tomography and magnetic resonance angiography, are the safer and preferred methods for identifying aneurysms and thrombi. Digital substraction angiography has been found to be inadequate in showing thrombosed vessels. Follow-up computed tomography was performed in the documentation of the aneurysmal healing process. In patients receiving immunosuppressive treatment, intramural thrombus formation occurred and was followed by aneurysmal regression and disappearance. General principles for the treatment of systemic vasculitis are used in the treatment of BD.

Pulmonary involvement in adult-onset Still's disease.

Abstract: Adult-onset Still's disease (AOSD) is a rare splenic disorder with an unknown cause. It is not uncommon for AOSD to involve other organs, such as the liver; the kidney; the bone marrow; and, less often, the lungs. In this review, we discuss the pulmonary complications of AOSD. Pulmonary involvement in AOSD usually consists of pleural effusion or transient pulmonary infiltrates, but it may become life threatening if it progresses to the adult respiratory distress syndrome. Chronic conditions, such as restrictive lung disease, have also been reported in patients with AOSD. The only treatment currently available is high-dose steroids, although other agents, such as intravenous immunoglobulin, cyclophosphamide, and azathioprine, have been tried with some success.

Health-related quality of life in asthma.

Abstract: One aim of caring for adults and children with asthma should be the identification and treatment of the functional impairments that are troublesome to these patients in their daily lives. Studies have shown that correlations between measures of clinical asthma severity and control and health-related quality of life (HRQL) impairment are only weak to moderate. Therefore, HRQL must be measured directly. In recent years, HRQL questionnaires have been developed and validated to measure the functional (physical, social, emotional, and occupational) impairments that are important to both adults and children with asthma. Most questionnaires are now available in a range of languages. More recently, methods have been developed for the clinical interpretation on HRQL data. Assessment of asthma-specific HRQL can be included in both clinical trials and clinical practice, in conjunction with the conventional measures of airway function, to provide a complete picture of patients' health status.

Clinical courses and prognoses of pulmonary sarcoidosis.

Abstract: In this article, long-term prognoses and prognostic factors of patients with sarcoidosis are reviewed. In patients with intrathoracic sarcoidosis, functional impairments and parenchymal lesions at the time of initial examination strongly predicted an unfavorable prognosis. We also discussed the significance of extrathoracic lesions in terms of clinical outcomes of intrathoracic sarcoidosis. In addition, we focused on the genetic approach and the new insights being offering with respect to the disease susceptibility and the development of pulmonary lesions.

Pulmonary associations in familial Mediterranean fever

Abstract: Familial Mediterranean fever (FMF) is a hereditary periodic fever syndrome expressed by acute episodes of fever and painful manifestations. In this report, the pulmonary manifestations of FMF are reviewed, the most prominent of which are chest attacks due to pleuritis. Nephropathic amyloidosis of the AA type, which complicates FMF in most untreated patients, may progress to affect other organs, including the lungs, but this rarely produces noticeable symptoms. The common association between FMF and vasculitis makes pulmonary hemorrhage, infarction, or infiltrates highly possible. These complications, however, have been reported only rarely. Asthma was found to occur less often than expected in patients with FMF, but methodologic faults make this finding doubtful. Finally, the occurrence of mesothelioma in five patients with FMF who were not exposed to asbestos suggests a role for recurrent FMF serositis in the pathogenesis of this malignancy.

Epidemiology of respiratory infectious diseases.

Abstract: Respiratory infections are a frequent burden to health despite the fact that cost-effective methods for their prevention and cure are available. Acute respiratory infections in children under 5 years of age are the most frequent cause of death from lung disease globally, causing more than 4 million deaths annually. Tuberculosis is the most frequent cause of death from a single pathogen in persons aged 15 to 49 years (a total of 2 million to 3 million deaths annually). Respiratory infections are the most frequent complications of immune deficiency (whether due to HIV infection or induced by chemotherapy). Where a "carrier state" occurs (as with many bacterial pathogens), the level of immune function is the key determinant in appearance of disease. Where there is no carrier state (as with many viruses), exposure is the key determinant. Characteristics of the pathogen, including virulence and bacterial load where there is a carrier state, also determine the probability of respiratory infections. Modifiers of these determinants include allergy and toxic exposures including tobacco smoke and ambient pollution.

A new look at hypersensitivity pneumonitis

Abstract: Hypersensitivity pneumonitis is an immunologically induced lung disease. Although both immune complex-mediated immune response and T cell-mediated immune response are involved in the pathogenesis of the disease, recent studies show the latter mechanism to be more important. As for T cell-mediated immune response, Th1/Th2 and Tc1/Tc2 cytokines produced by CD4+ and CD8+ T cells play important roles in the development of granulomatous inflammation in the lung, a pathologically characteristic feature of the disease. The critical distinction between CD4+ and CD8+ T cells pertains to recognition of antigens presented by different major histocompatibility complex molecules. Serum levels of KL-6 and soluble intercellular adhesion molecule-1 in patients with HP are useful markers of the disease activity. The chronic form of HP can be difficult to diagnose, and provocation testing is helpful. Erythromycin might be useful for anti-inflammatory therapy.

The challenge of inner-city asthma.

Abstract: Racial and ethnic minorities of low socioeconomic status residing in urban environments currently referred to as inner cities appear to represent a population that is disproportionately at high risk for asthma morbidity and mortality Epidemiologic studies suggest that key risk factors contributing to asthma morbidity within the inner city include social demography, the physical environment (indoor and outdoor), and health care access and quality This epidemiologic literature has helped to define opportunities for successful intervention strategies in these high-risk populations Studies of the effectiveness of community-based and health system-based interventions with specific focus on inner-city populations are beginning to emerge in the literature

Physical activity and asthma.

Abstract: The relationship between asthma and exercise and the resultant disability (ie, the impact on activities of daily living, including physical activity) shows wide interpatient and intrapatient variability, being influenced not only by the disease but additional psychosocial variables. There are a variety of helpful pharmacologic and nonpharmacologic measures in dealing with simple exercise-induced asthma, and new therapeutic options are being developed. The cardiorespiratory performance characteristics of asthmatic patients are very frequently suboptimal, either because of symptom-limited exercise tolerance or secondary deconditioning consequent upon inactivity. Medically supervised physical training can produce significant beneficial change. Recommendations for rehabilitation of asthmatic patients would include individualized exercise prescription and advice based on objective criteria of exercise capability, with flexibility in the programs offered, in order to cater to the broadest spectrum of patient disability.

Gastroesophageal reflux disorders and asthma.

Abstract: Gastroesophageal reflux (GERD) may trigger asthma. Approximately 77% of asthmatic people experience reflux symptoms, although GERD may be clinically silent in some. Esophagitis is found in 43% of asthmatic people, and 82% have abnormal esophageal acid contact times on esophageal pH testing. Clearly, GERD is prevalent in asthmatic people. Pathophysiologic mechanisms of acid-induced bronchoconstriction include a vagally mediated reflex and microaspiration. Whether these airway responses are clinically significant is the subject of some debate. Interestingly, peak expiratory flow rates and specific airway resistance alterations persist despite esophageal acid clearance. Preliminary evidence shows that substance P, an inflammatory mediator that causes airway edema, is released with esophageal acid. Although therapeutic studies are limited by their small population sizes and study design, up to 70% of asthmatic people have asthma improvement with antireflux therapy. Possible predictors of asthma response include patients with symptomatic esophageal regurgitation; abnormal proximal esophageal acid exposure; and, in surgical studies, those with normal esophageal motility and asthma response with medical therapy. Future research will further define the association between asthma and gastroesophageal reflux.

Neuromuscular disease and hypoventilation.

Abstract: Alveolar hypoventilation associated with neuromuscular disease can occur in acute and chronic forms. In the acute form, progressive weakness of respiratory muscles leads to rapid reduction in vital capacity followed by respiratory failure with hypoxemia and hypercarbia. Symptoms are those of acute respiratory failure, including dyspnea, tachypnea, and tachycardia. In the chronic form, impairment of the respiratory muscles affects mechanical properties of the lungs and chest wall, decreases the ability to clear secretions, and eventually may alter the function of the central respiratory centers. Symptoms include orthopnea, fatigue, disturbed sleep, and hypersomnolence. Treatment and outcome of the disease's chronic form are dependent on the underlying clinical cause of the alveolar hypoventilation. For chronic but stable diseases such as old polio, quadriplegia, or kyposcoliosis, mechanical support of minute ventilation can reverse symptoms. For chronic and progressive disease such as muscular dystrophy and amyotrophic lateral sclerosis, mechanical support of minute ventilation provides only symptomatic relief and is usually associated with deterioration to the point of complete ventilator dependency for survival. For the chronic progressive forms of alveolar hypoventilation, there is currently a need for quality randomized controlled clinical trials to define physiologic indicators and appropriate timing for mechanical support of minute ventilation.

Novel insights into congenital hypoventilation syndrome

Abstract: Congenital central hypoventilation syndrome (CCHS) is a rare and unique condition that may prompt unparalleled approaches to the discovery of genes involved in development of cardiorespiratory control and gas exchange homeostasis. Its higher risk of recurrence in families and its association with Hi

Role of reactive oxygen species in occupational and environmental obstructive pulmonary diseases.

Abstract: Free radicals and their metabolites, also called reactive oxygen species (ROS), have been implicated in the pathogenesis of many diseases. Because of its continuous exposure to toxic pollutants in the ambient air, such as cigarette smoke, air pollution, and mineral dusts, the lung is very vulnerable to ROS-induced injury. In this review, the role of ROS in the pathogenesis of obstructive lung diseases is reviewed. A central theme in this review is the pivotal role of transition metals such as iron, vanadium, and nickel in ROS-induced cell damage, not only in exposure to mineral dusts but also in cigarette smoke and air pollution.

Anti-IgE as novel therapy for the treatment of asthma.

Abstract: Immunoglobulin-E (IgE) is believed to be the central effector antibody reacting to allergen in patients with allergic asthma. Clinical manifestations of allergic asthma result from the release of chemical mediators from mast cells and basophils on exposure to allergen. A humanized murine monoclonal antibody to IgE, rhuMAb-E25, recognizes the specific Fc epsilon3 portion of circulating IgE that binds to the high-affinity IgE receptor, Fc epsilonRI. In clinical studies, single and multiple doses of subcutaneous and intravenous rhuMAb-E25 have been shown to reproducibly reduce the serum free IgE concentrations in a dose-dependent manner. Clinical trials conducted in aeroallergen bronchoprovocation laboratories demonstrated that decreasing circulating IgE resulted in significant attenuation of the early and late asthmatic responses. Studies completed in moderate to severe allergic asthmatics have extended the safety and efficacy of rhuMAb-E25. Significant improvements in asthma symptoms, meaningful reductions in corticosteroid agents while decreasing reliance on bronchodilator rescue drugs, decreased asthma exacerbations, and improved quality of life have been documented. Because of the remarkable protein engineering and the humanization technology now available, rhuMAb-E25 therapy has elicited no antibody responses and has been safely administered to atopic subjects. rhuMAb-E25 as a novel monoclonal antibody, the first to be applied to lung diseases, holds promise for the control of many IgE-mediated diseases.

New approaches to optimizing antimicrobial therapy in patients with cystic fibrosis.

Abstract: Chronic pulmonary infections are a significant cause of morbidity and mortality in patients with cystic fibrosis. The traditional approach to managing patients with cystic fibrosis is to treat acute exacerbations with antimicrobial, airway clearance, and nutritional therapies. Advances in the understanding of the pharmacodynamics of antibiotics have led to the development of new dosing strategies to maximize the antibiotics' activity. Recent data on the use of aerosolized tobramycin as chronic maintenance therapy have demonstrated that it improves pulmonary function significantly and reduces hospitalization days. New insights into the pathogenesis of pulmonary disease have led to the development of novel therapies, including salt-insensitive antimicrobial peptides and rBPI21, as adjunctive therapy to increase the sensitivity of current antibiotics. In addition, macrolide antibiotics are being investigated for their anti-inflammatory effects as chronic maintenance therapy. Until effective therapies are available to correct the basic genetic defect that causes cystic fibrosis, antibacterial and anti-inflammatory agents will continue to be the mainstay of treatment.

Effects of long-term oxygen therapy in patients with chronic obstructive pulmonary disease.

Abstract: Long-term oxygen therapy is largely used in the management of severe hypoxemia in patients with chronic obstructive pulmonary disease. It was demonstrated that long-term oxygen therapy prolongs life, prevents progression of hypoxic pulmonary hypertension, and controls polycythemia. Recent data suggest that in patients with moderate hypoxemia (Pao2 > 55 mm Hg), long-term oxygen therapy does not prolong life. Life expectancy in those patients seems to depend on the severity of airway obstruction. Long-term oxygen therapy improves cognitive functions and emotional status. There is some evidence suggesting that it also improves quality of life, but more data are needed. There are conflicting data concerning the rationale for nocturnal oxygen supplementation in patients with arterial blood desaturation during sleep.

The relationship between allergic rhinitis and bronchial asthma.

Abstract: Allergic rhinitis and bronchial asthma frequently coexist in the same patients. Many patients with rhinitis alone demonstrate nonspecific bronchial hyperresponsiveness, and prospective studies suggest that nasal allergy may be a predisposing risk factor for developing asthma. A growing body of literature has documented that the treatment of patients with allergic rhinitis may result in improvement of asthma symptoms, airway caliber, and bronchial hyperresponsiveness to methacholine and exercise. Finally, mechanistic studies of airway physiology have demonstrated that nasal disease may influence pulmonary function via both direct and indirect mechanisms. Nasal disease should be considered as a possible concomitant illness in all patients with asthma and treated appropriately when identified.

The 21st century environment and air quality influences on asthma.

Abstract: "Criteria" air pollutants are federally regulated pollutants that occur widely outdoors and have diverse sources, most often related to combustion. They include ozone (O3), particulate matter, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and lead. All except lead may interfere with oxygen delivery, and so may be of special concern to asthmatics. In controlled experiments, SO2 causes acute asthma symptoms and bronchoconstriction, preventable by beta-agonist medications. Ozone causes acute irritant symptoms, restrictive lung dysfunction, increased bronchial reactivity, and lower-airway inflammation in healthy people and asthmatics. Exposures to O3, and possibly to other pollutants, appear to exacerbate bronchoconstrictive or inflammatory responses to inhaled aeroallergens (bioaerosols); this may represent an important health risk to asthmatics. Exposure levels known to evoke acute responses to O3 or SO2 are uncommon in community air pollution; however, some asthmatics might be susceptible to lesser, more common exposures. Evidence concerning NO2 is equivocal, but it may have O3-like effects in some asthmatics. Epidemiology has often associated particulate pollution with asthma exacerbations and other cardiorespiratory illnesses, even in cities with relatively mild air pollution. Current laboratory research cannot fully explain this association. Advances in emission controls should further reduce ambient pollution levels, but probably will not reduce asthma morbidity. Better asthma management, with improved anti-inflammatory medications, more careful monitoring by patients and health care providers, and reasonable efforts to reduce pollutant and aeroallergen exposures, offers the best hope to reduce asthma morbidity in the new century.

Genetic control of ventilation: what are we learning from murine models?

Abstract: Advances in human and mouse genomes are revolutionizing research in lung biology and pulmonary medicine. Genomic strategies are available that link functional variation to molecular structure, and these approaches are currently being applied to the study of ventilatory control mechanisms. In this re

Pulmonary veno-occlusive disease.

Abstract: Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension that mainly affects children and young adults. Its cause is unknown, although viral infections and drugs have been implicated. Patients with PVOD present with symptoms of right-sided heart failure. Radiologic examination shows prominent pulmonary arteries with Kerley B lines, pleural effusion, and mediastinal adenopathy. The definite diagnosis is made by histologic examination. Eccentric intimal fibrosis and recanalized thrombi in pulmonary veins and venules, arterialized veins, alveolar edema, and medial hypertrophy of arteries are seen on lung biopsy. No effective treatment is available; lung transplantation has been tried. The prognosis associated with PVOD is poor.

Defense mechanisms against infections.

Abstract: Respiratory infections remain common and may be more difficult to treat because new microbes have been identified; commensal flora can become pathogens; and antibiotic resistance is developing, especially to Streptococcus pneumoniae. Contributing to the severity of pneumonia is the increasing number of more susceptible hosts--immunodeficient patients, created as a by-product of modern medical therapy or from infection with HIV, and elderly patients who have associated illnesses. Better strategies to replete immunocompromised hosts are required. Vaccination to modify infection with S. pneumoniae must be given higher priority by health care providers. New means to immunize the respiratory mucosal surface are needed. Research approaches to consider involve 1) targeting (carrying) relevant antigens to appropriate antigen-processing cells in the airways, eg, dendritic cells; and 2) coupling the immunomodulatory effects of cytokines, eg, interleukin-12. Interleukin-12, for example, can stimulate mucosal antibody responses producing S-IgA and IgG and cause T lymphocytes to produce interferon-gamma that can enhance microbial killing by macrophages.

Serum measurement of eosinophil cationic protein in the management of asthma.

Abstract: Asthma is a disease characterized by chronic eosinophilic inflammation of the airways. Serum eosinophil cationic protein (ECP) has been increasingly used as a noninvasive inflammatory marker in asthma. The serum ECP level seems to reflect, although indirectly, the intensity of ongoing eosinophilic inflammation of the airways and respond sensitively to intervention, whereas it is unlikely to be useful for establishing the diagnosis of asthma in an individual patient. Monitoring of serum ECP could be of utility in the long-term follow-up of asthmatic patients. However, further longitudinal studies are required to establish the role of serum ECP measurement in the treatment modulation in asthma.

The role of newer diagnostic techniques in the diagnosis of pulmonary embolism.

Abstract: Among the evolving techniques for the diagnosis of acute pulmonary embolism, contrast enhanced spiral CT takes a particularly prominent role because it is available at most centers, it images the pulmonary embolism directly, and it is minimally invasive. It has not yet been fully evaluated, however.

Lung transplantation for cystic fibrosis: an update and practical considerations for referring candidates.

Abstract: In this article, the authors provide an update to Maurer and Chaparro's 1995 review in this journal of lung transplantation for cystic fibrosis. Bilateral (sequential) cadaver donor transplantation is the usual procedure of choice. The four-year survival rate for adult, all-disease, double-bilateral lung transplantation has improved to 53%. Because of lower [corrected] survival rate among adults, living-donor lobar transplantation should be performed only when cadaver lungs are unlikely to become available. The International Society for Heart and Lung Transplantation and the Cystic Fibrosis Foundation have promulgated uniform guidelines for transplantation candidate selection. Issues of diabetes mellitus, mechanical ventilation, osteoporosis, malnutrition, fungi and drug-resistant bacteria, pleural fibrosis, and sinusitis in relation to transplantation candidacy are discussed. Some practical points regarding transplantation center referral are presented, and a list of cystic fibrosis transplantation centers in the United States is supplied.

Perinatal events in the development of asthma.

Abstract: Many potential factors are likely involved in the pathogenesis of asthma. These include prenatal, peripartum, and postnatal influences. Prenatally, genetic endowment, maternal smoking, in utero allergen sensitization, and alterations in maternal immune function, especially at the placental level, may increase the risk for asthma and atopy. In the peripartum period, suspected factors include obstetric practices (eg, the use of prostaglandins, hormones, and other agents) and prematurity. Postnatally passive smoke exposure, neonatal or early childhood infections and breast-feeding are under increasing scrutiny as to their possible role in the development of asthma. Despite the volumes of work already reported, much more is left to be done to sort out the complex interrelationships of these and other as yet unsuspected influences on the development of asthma.

Role of ventilatory drive in asthma and chronic obstructive pulmonary disease.

Abstract: The ventilatory drive is affected by several factors such as chemosensitivity, basal arterial oxygen or carbon dioxide tension, mechanical impedance, and respiratory muscle dysfunction. Blunted ventilatory drive or a decrease in the perception of dyspnea in bronchial asthma and chronic obstructive pulmonary disease (COPD) could lead to a decrease in the alarm reaction to dangerous situations such as severe airway obstruction, severe hypoxemia, or severe hypercapnia. This could delay management and treatment, causing an increase in the morbidity and mortality of patients with bronchial asthma and COPD. The ventilatory drive to chemical stimuli can be altered by a beta-2-agonist, oxygen administration; and lung volume reduction, and an increased dyspnea sensation may be improved by corticosteroid, chest wall vibration, or lung volume reduction. The ventilatory drive has been found to play a key role in determining the severity of asthma and COPD.