Background: Mediastinal affections are common and encompass a great number of different diagnoses. Objective: To analyze the clinical aspects and the therapeutic response of 114 patients with mediastinal diseases treated at the Thoracic Surgery Department of Santa Casa de São Paulo Hospital, from 1979 and 1997. Method: The patients were grouped according to the benign or malignant nature of the disease, and the two groups were compared regarding gender, age bracket, symptomatology, topography of the lesion, mortality, and response to treatment. Results: Sixty-three patients had neoplasia: 31 benign and 32 malignant. Fifty-one cases were not neoplastic. No difference was found between the groups regarding gender or age bracket. Half of the patients were between 20 and 49 years of age. The anterior mediastinum was the most frequently affected compartment (66 patients), followed by the upper mediastinum (18 patients), the posterior mediastinum (16 patients), and the middle mediastinum (14 patients). The most frequent histological types were: benign thymus diseases (N = 40), mesenchymal tumors (N = 17), lymphomas (N = 15), neural tumors (N = 9), and germ cell tumors (N = 8). Malignant tumors were more frequently symptomatic (91%), and benign tumors were more frequent in asymptomatic patients (92%). The most frequent symptoms were related to myastenia gravis, followed by dyspnea and chest pain. Weight loss, anorexia and fever were significantly more frequent in patients with malignant neoplasias. Conclusions: Regarding the clinical aspects we can state that benign lesions were predominant, that mediastinal diseases were more prevalent in young adults, and that benign lesions were more frequent in asymptomatic patients. Treatment (clinical/surgical) was effective in most patients, benefiting approximately 90% of the patients with benign affections and 45% of the patients with malignant tumors. In 73% of the benign affections, surgical treatment was capable of achieving the cure. Mortality resulting from complications was 1.75%.

Keywords: Key words - Mediastinum. Mediastinal disease/epidemiology. Mediastinal neoplasms.

Objectives: To evaluate clinical, laboratorial, epidemiological, and therapeutic aspects of patients presenting with multiresistant tuberculosis (MRTB). Patients and methods: From January 1993 to December 1994, a prospective, non-randomized study of patients presenting MRTB, characterized by failures under treatment schemes E-1 and E-3 according to the classification of the Brazilian Ministry of Health, and resistance to isoniazid and rifampicin was carried out. Clinical and laboratorial aspects were considered: age, gender, ethnical group, duration of condition, cavity occurrences in conventional X-rays, resistance to drugs by the indirect method according to Canetti's et al. proportional criteria; epidemiological aspects such as risk predictor factors for multiresistance and treatment results. This study consisted in two alternative chemotherapy courses combining an aminoglycoside, amikacin (Group A), or S, if sensitive (Group B), ofloxacin, clofazimine, in addition to other drugs, such as thiacetazone, ethambutol, or pyrazinamide, according to the sensitivity or to the prior limited use for a minimum of twelve months. Patients with unilateral radiologic lesions, functional possibilities, and who have accepted the indication were submitted to surgery (Group C). Treatment was at the outpatient clinic, self-administered, or under indirect supervision, with hospital admission allowed for clinical reasons, for a limited time, or when surgery was indicated. Patients with prior alternative treatment, those infected with HIV, pregnant patients, and those with renal failure were excluded from the study. Evaluation extended to twelve months after completion of treatment. Results: 70 patients with mean age of 37 years, 42 male, 44 caucasian, and 26 non-caucasian (two orientals), average duration of the condition of four years, and bilateral cavitary lesions in 55 (78.6%). Resistance to two drugs in 28.6%, 51.4% to three drugs, and 20% to four drugs. The most frequent risk predictor factor for MRTB was abandonment (54.3%) followed by recurrence after cure with treatment scheme E1 and failure at retreatment (14.3%), intolerance to drugs (11.4%), contact with MRTB (8.6%). The risk predictor factor could not be determined in 11%, acquired multiresistance being considered in 80%, and primary multiresistance in only 8.6% of the patients. Cure was observed in 25 patients of Group A (n = 39), 11 patients of Group B (n = 24), and 3 of Group C (n = 7). Only two discontinued treatment (A) and only two died during treatment (C). In the control period, three patients had recurrences (1 in A, and 2 in B), and 7 died (3 in A, 2 in B, and 2 in C). The effectiveness of Group A was 67.6% (25/37) at completion of treatment, and 64.9% during the post-treatment control. The effectiveness of Group B was 45.8% (11/24) at completion of treatment, and 37.5% during the post-treatment control. The effectiveness of Group C was 42.8% (3/7) at completion of treatment and during the post-treatment control. After twelve months, effectiveness at treatment completion in Group A fell from 64.1% to 61.5%, in Group B, it fell from 45.8% to 37.5%, and it remained unchanged in 42.8% in Group C, where the four cases of failure died. Drug discontinuation due to adverse effects occurred late in two cases, and other adverse effects were noted, but did not foster discontinuation of treatment.

In humans, the most common types of infection are respiratory tract infections, among which viral infections predominate. Viruses can also infect the low respiratory tract, causing bronchiolitis, bronchitis and pneumonia. The objective of this review article was to show epidemiological, pathophysiological, clinical and therapeutic aspects of viral community-acquired pneumonia. These types of pneumonia are commonly caused by influenza A and B; parainfluenza 1, 2 and 3; respiratory syncytial virus; or adenovirus. We also address the types of pneumonia caused by hantaviruses, metapneumoviruses and rhinoviruses.

Keywords: Pneumonia, viral; Influenza, human; Respiratory syncytial virus infections; Hantavirus.

Once considered a childhood disease, cystic fibrosis is now also a disease of adults. Increased longevity has resulted in the aging of the cystic fibrosis population. The consequent age-related medical problems among adults with cystic fibrosis have increased medical care needs. These needs are being met by a growing number of non-pediatric pulmonologists and other non-pediatric specialists. The objective of this review was to summarize the current knowledge about diagnosis and treatment in adult cystic fibrosis. In most cases, the diagnosis is suggested by manifestations of chronic sinopulmonary disease and exocrine pancreatic insufficiency. The diagnosis is confirmed by a positive sweat test result. Adult patients may, however, present pancreatic sufficiency and atypical clinical features, sometimes in combination with normal or borderline sweat test results. In such cases, identifying cystic fibrosis mutations and measuring nasal potential difference can have diagnostic utility. The standard therapeutic approach to pulmonary disease includes the use of antibiotics, airway clearance, exercise, mucolytics, bronchodilators, oxygen therapy, anti-inflammatory agents and nutritional support. Appropriate application of these therapies results in most cystic fibrosis patients surviving into adulthood with an acceptable quality of life.

Keywords: Cystic fibrosis; Diagnosis; Therapeutics; Mucoviscidosis.

INTRODUCTION: Cystic Fibrosis is usually diagnosed in childhood. In Brazil, few studies have approached CF diagnosed in adulthood. OBJECTIVE:The aim of this study was to describe demographic and clinical characteristics and spirometric data of patients with CF diagnosed in adulthood (over 16 years of age) in Bahia, Brazil. METHODS: Twenty-eight patients with cystic fibrosis diagnosed in adulthood were evaluated at the Reference Center of Cystic Fibrosis of the state of Bahia. Variables of interest were age, gender, race, body mass index (BMI), sputum culture, presence of sinusitis and bronchiectasis, spirometric tests with the best values performed for forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and response to bronchodilators. RESULTS: Mean age of diagnosis was 31.1 ± 12.4 years. Of the patients, 53.4% were black and mulatto and the mean BMI was 18.7 ± 3.0 kg/m2. P aeruginosa was present in 12 (43%) of the total patients. The mean percentages ± SD of FVC and FEV1 were 58.9 ± 21.6% and 44.1 ± 23%, respectively. In the group of patients with presence of P. aeruginosa in sputum cultures, mean of the spirometry parameters were lower than those of the P. aeruginosa-free group. However, this difference achieved a statistically significant difference (p = 0.0007) only in FVC . CONCLUSIONS: In agreement with many authors, this study strengthen the point of view that CF must be investigated in patients with recurrent infections, sinusitis and bronchiectasis even in adulthood. Values of the percentages of FVC and FEV1 in relation to those foreseen were lower in patients bearers of P. aeruginosa thereby showing a higher deterioration of the pulmonary function.

Keywords: Cystic fibrosis/diagnosis. Adult. Spirometry/methods.

Objective: To describe the clinical manifestations and bronchoscopic treatment of foreign body aspiration in children under 14 years of age, correlating the clinical aspects with the bronchoscopic findings. Methods: A retrospective, descriptive study analyzing data related to children under 14 years of age undergoing bronchoscopy due to clinical suspicion of foreign body aspiration at the State University at Campinas Hospital das Clinicas from January of 2000 to December of 2005. Results: The sample consisted of 69 patients, ranging in age from 8 months to 12 years/7 months (75.4% under 3 years of age), 62.3% of whom were male. The principal complaint was sudden-onset cough (75.4%), auscultation was abnormal in 74%, and dyspnea was observed in 29%. Radiological abnormalities were seen in 88% of the cases. Aspirations were primarily into the right lung (54.8%), and 30.7% of the foreign bodies were of vegetal origin (principally beans and peanuts). In the follow-up period, 29% presented complications (most commonly pneumonia), which were found to be associated with longer aspiration time (p = 0.03). Mechanical ventilation was required in 7 children (10.1%), and multiple bronchoscopies were performed in 5 (7.2%). Conclusion: A history of sudden-onset choking and cough, plus abnormal auscultation and radiological findings, characterizes the profile of foreign body aspiration. In such cases, bronchoscopy is indicated. Longer aspiration time translates to a higher the risk of complications. The high prevalence of foreign bodies of vegetal origin underscores the relevance of prevention programs aimed at children younger than 3 years of age.

Keywords: Foreign bodies; Bronchoscopy; Pediatrics.

The present article purports to analyze aspects related to the concept of quality of life, taking into account the relevance of setting down parameters that allow for the evaluation of those aspects, especially in patients with chronic diseases. The analysis considered quality of life as one of the essential components of medical care, and pointed out the precautions that should be taken to choose instruments of evaluation, that should be sensitive and reliable to the dimensions they intend to evaluate.

Keywords: quality of life, chronic diseases, asthma, chronic obstructive pulmonary disease

Primary immunodeficiency diseases comprise a genetically heterogeneous group of disorders that affect distinct components of the innate and adaptive immune system, such as neutrophils, macrophages, dendritic cells, complement proteins and natural killer cells, as well as T and B lymphocytes. The study of these diseases has provided essential insights into the functioning of the immune system. Primary immunodeficiency diseases have been linked to over 120 different genes, abnormalities in which account for approximately 180 different forms of these diseases. Patients with primary immunodeficiency diseases are most often recognized because of their increased susceptibility to infections. However, these patients can also present with a variety of other manifestations, such as autoimmune diseases, inflammatory diseases and cancer. The purpose of this article is to update the main aspects of primary immunodeficiency diseases, especially regarding the clinical manifestations related to the diagnosis, emphasizing the need for the early recognition of warning signs for these diseases.

Keywords: Respiratory tract infections; Complement activation; Immunologic deficiency syndromes; Phagocytes; Immunoglobulins.

Objective: To present aspects of the evolution of lipoid pneumonia in children, based on clinical, radiological and bronchoalveolar lavage fluid findings, emphasizing the importance of bronchoalveolar lavage for the diagnosis and treatment. Methods: We included 28 children, with a mean age of 20 months (range, 1-108 months), diagnosed with chronic pneumonia refractory to antimicrobial therapy, with TB or with a combination of the two. Most of the children had at least one risk factor for aspiration, and all of them had a history of mineral oil ingestion for intestinal constipation (23/28) or complicated ascaridiasis (5/28). Clinical evaluations, tomographic evaluations and analyses of bronchoalveolar lavage fluid were carried out at the beginning of treatment and throughout a follow-up period of 24 months. Results: Tachypnea and cough were the most common symptoms. The most common radiological alterations were areas of consolidation (23/28), perihilar infiltrates (13/28) and hyperinflation (11/28). Chest CT scans showed areas of consolidation with air bronchogram (24/28), decreased attenuation in the areas of consolidation (16/28), ground-glass opacities (3/28) and crazy-paving pattern (1/28). In the analysis of the bronchoalveolar lavage fluid, Sudan staining revealed foamy macrophages, confirming the diagnosis of lipoid pneumonia. After treatment with multiple bronchoalveolar lavages (mean = 9.6), 20 children became asymptomatic, 18 of those presenting normal tomographic images. Conclusions: A diagnosis of lipoid pneumonia should be considered in patients with chronic refractory pneumonia or TB, especially if there is a history of mineral oil ingestion. Bronchoscopy with multiple bronchoalveolar lavages was an efficient treatment for the clearance of mineral oil from the lung parenchyma and the prevention of fibrosis. This strategy contributed to reducing the morbidity of lipoid pneumonia, which remains a rare diagnosis.

Keywords: Pneumonia, lipid; Bronchoalveolar lavage; Treatment outcome.

Objective: To analyze the association of dysglycemia with clinical, laboratory, and radiographic characteristics of patients with pulmonary tuberculosis (PTB), as well as with their tuberculo-sis treatment outcomes. Methods: This was a longitudinal study involving 140 patients diag-nosed with PTB (positive cultures for Mycobacterium tuberculosis or positive Xpert MTB/RIF results from sputum samples). Patients were evaluated at diagnosis (M0), after completing the second month of treatment (M2), and at the end of treatment (MEND). At M0, the pati-ents were classified into three groups: normoglycemia+PTB (NGTB); pre-diabetes melli-tus+PTB (PDMTB), and diabetes mellitus+PTB (DMTB), in accordance with glycated hemoglo-bin levels (< 5.7%, 5.7%-6.4%, and = 6.5%, respectively). Treatment outcomes were classified as favorable (cure or treatment completion) and unfavorable (death, loss to follow-up, or treatment failure). Results: In our sample, 76 patients (61.4%) had dysglycemia, 20 of whom (14.3%) had DM at M0. The patients with dysglycemia, in comparison with those in the NGTB group, more frequently presented with positive sputum smear microscopy (94.2% vs. 75.9%; p = 0.003); cavities (80.2% vs. 63.0%; p = 0.03); bilateral lesions (67.4% vs. 46.0%; p = 0.02); and higher median of affected thirds of the lungs (3.0 vs. 2.0; p = 0.03) on chest radiography. No significant differences regarding outcomes were found among the groups, but tuberculosis lethality was higher in the DMTB group than in the PDMTB and NGTB groups (20% vs. 2.2%). Conclusions: PTB patients with dysglycemia had laboratory and radiographic manifestations indicative of more advanced disease, and the risk of death was higher in the DMTB group. These findings reinforce the recommendation for early screening for DM in patients with newly diagnosed tuberculosis in order to reduce the risk of death during treatment.

Keywords: Tuberculosis/diagnosis; Tuberculosis/diagnostic imaging; Tuberculosis/therapy; Diabetes mellitus; Treatment outcome.

BACKGROUND: The clinical evaluation of patients with post-infectious bronchiolitis obliterans (BO) is variable. OBJECTIVE: Substantiate the clinical characteristics, the evolution and the complementary tests of 48 patients with post-infectious bronchiolitis obliterans (BO). METHOD: Observational and retrospective study. Diagnosis of BO was based upon clinical criteria, CT scan findings and exclusion of other diseases. History prior to diagnosis and complementary tests were evaluated as well as initial and final values of oxygen saturation. RESULTS: Mean age of patients at the acute stage of the infectious disease was of 9.6. Thirty two of the patients were male. All were hospitalized during the acute stage, 14 of them (29%) in the ICU. Four patients died two years after onset of acute bronchiolitis. During evolution, all required emergency care due to exacerbation of the pulmonary condition and 24 (50%) were hospitalized, 2 of them in the ICU. The majority continued presenting cough, wheezing, crackles and hyperinflation, however to a lesser degree. Mean of initial arterial saturation was of 89% and final of 92%. The most common infectious agents in sputum samples were H. influenzae, S. pneumoniae and M. catarrhalis. Increased serum IgM and IgC were found in 9 and 7 patients, respectively. The most frequent findings at thorax CT scan were mosaic perfusion, bronchiectasis, atelectasis and bronchial wall thickening. CONCLUSION: Post infectious BO is a chronic and severe disease with persistent symptoms that in general affect infants. Positive serum cultures and increased serum immunoglobulins are suggestive of chronic infectious inflammatory condition.

Keywords: Bronchiolitis obliterans. Obstructive lung diseases.

Objective: To analyze the clinicopathological aspects of bronchioloalveolar carcinoma (BAC) and the survival in a sample of patients at clinical stage I. Methods: A retrospective study involving 26 patients diagnosed with clinical stage I BAC and undergoing surgery at the Thoracic Diseases Institute of the Federal University of Rio de Janeiro, in the city of Rio de Janeiro, Brazil, between 1987 and 2007. We analyzed clinicopathological and radiological aspects, as well as mortality and survival. The data, which were collected from the medical charts of the patients, were statistically analyzed. Results: Females predominated (n = 16). The mean age at diagnosis was 68.5 years. Most patients were active smokers (69.2%). The most common forms of presentation of BAC were the asymptomatic form (84.6%) and the nodular form (88.5%). Involvement of the upper lobes predominated (57.7%). Stage IB was the most common pathological stage, followed by stages IA and IIB (46.2%, 38.4% and 15.4%, respectively). There was no in-hospital mortality. Four patients died during the postoperative follow-up, with a mean disease-free survival time of 21.3 months. The overall five-year survival rate was 83%. The probability of survival for the patients diagnosed after 1999 showed a trend toward an increase when compared with that for those diagnosed up through 1999 (three-year survival rate: 92% vs. 68%; p = 0.07). Conclusions: The clinicopathological aspects of this study sample were similar to those of patients with BAC evaluated in previous studies.

Keywords: Adenocarcinoma, bronchiolo-alveolar; Carcinoma, non-small-cell lung; Lung; Smoking.

O diafragma é o principal músculo da respiração e age de forma contínua e ininterrupta para mantê-la. Muitas patologias podem causar disfunção diafragmática, que é geralmente subdiagnosticada na prática clínica em virtude de sua apresentação inespecífica. Embora várias técnicas tenham sido usadas na avaliação da função diafragmática, o diagnóstico de disfunção diafragmática ainda é problemático. A ultrassonografia diafragmática ganhou importância em virtude de suas muitas vantagens: não é invasiva, não expõe os pacientes à radiação, está amplamente disponível, fornece resultados imediatos, é altamente precisa e é repetível à beira do leito. Vários autores descreveram técnicas ultrassonográficas para avaliar a excursão e o espessamento diafragmático na zona de aposição. Estudos recentes propuseram a padronização dos métodos. Este artigo de revisão analisa a utilidade da ultrassonografia na avaliação da função diafragmática, abordando os detalhes da técnica, os principais achados e as aplicações clínicas.

Keywords: Ultrassonografia; Diafragma/diagnóstico por imagem; Músculos respiratórios; Estado terminal; Doenças respiratórias; Doenças neuromusculares.

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension. Surgical biopsy was usually required for diagnostic confirmation. However, the morbidity, mortality and limited benefit of this procedure have generated discussion regarding noninvasive diagnostic techniques. We present the case of a female patient with progressive dyspnea, hypoxemia and pulmonary hypertension, the last diagnosed via catheterization. Computed tomography revealed septal thickening and diffuse micronodules. Bronchoalveolar lavage revealed occult alveolar hemorrhage. Treatment with an endothelin antagonist was started, resulting in symptomatic and functional improvement. Occult alveolar hemorrhage differentiates PVOD from idiopathic pulmonary hypertension. We believe that this finding, in combination with characteristic tomographic findings, is sufficient to establish a diagnosis of PVOD.

Keywords: Hypertension, pulmonary; Pulmonary veno-occlusive disease; Bronchoalveolar lavage; Receptors, endothelin/antagonists & inhibitors.

Objective: To characterize a population of patients with bronchiectasis, correlating clinical, radiological, and functional aspects with the severity of dyspnea. Methods: This was a cross-sectional study involving adult patients with HRCT-confirmed bronchiectasis, categorized according to the severity of dyspnea (as being mildly or severely symptomatic, on the basis of the modified Medical Research Council scale). We correlated the severity of dyspnea with clinical parameters, functional parameters (spirometry values, lung volumes, and DLCO), and CT parameters. Results: We evaluated 114 patients, 47 (41%) of whom were men. The median age (interquartile range) was 42 years (30-55 years). The most common form was idiopathic bronchiectasis. Of the 114 patients, 20 (17.5%) were colonized with Pseudomonas aeruginosa and 59 (51.8%) were under continuous treatment with macrolides. When we applied the Exacerbation in the previous year, FEV1, Age, Colonization, Extension, and Dyspnea score, the severity of dyspnea was categorized as moderate in 54 patients (47.4%), whereas it was categorized as mild in 50 (43.9%) when we applied the Bronchiectasis Severity Index. The most common lung function pattern was one of obstruction, seen in 95 patients (83.3%), and air trapping was seen in 77 patients (68.7%). The prevalence of an obstructive pattern on spirometry was higher among the patients with dyspnea that was more severe, and most functional parameters showed reasonable accuracy in discriminating between levels of dyspnea severity. Conclusions: Patients with bronchiectasis and dyspnea that was more severe had greater functional impairment. The measurement of lung volumes complemented the spirometry data. Because bronchiectasis is a complex, heterogeneous condition, a single variable does not seem to be sufficient to provide an overall characterization of the clinical condition.

Keywords: Bronchiectasis; Dyspnea; Respiratory function tests; Multidetector computed tomography; Plethysmography.

Tuberculosis continues to be a public health priority in many countries. In 2015, tuberculosis killed 1.4 million people, including 210,000 children. Despite the recent progress made in the control of tuberculosis in Brazil, it is still one of the countries with the highest tuberculosis burdens. In 2015, there were 69,000 reported cases of tuberculosis in Brazil and tuberculosis was the cause of 4,500 deaths in the country. In 2014, the World Health Organization approved the End TB Strategy, which set a target date of 2035 for meeting its goals of reducing the tuberculosis incidence by 90% and reducing the number of tuberculosis deaths by 95%. However, to achieve those goals in Brazil, there is a need for collaboration among the various sectors involved in tuberculosis control and for the prioritization of activities, including control measures targeting the most vulnerable populations. Children are highly vulnerable to tuberculosis, and there are particularities specific to pediatric patients regarding tuberculosis development (rapid progression from infection to active disease), prevention (low effectiveness of vaccination against the pulmonary forms and limited availability of preventive treatment of latent tuberculosis infection), diagnosis (a low rate of bacteriologically confirmed diagnosis), and treatment (poor availability of child-friendly anti-tuberculosis drugs). In this review, we discuss the epidemiology, clinical manifestations, and prevention of tuberculosis in childhood and adolescence, highlighting the peculiarities of active and latent tuberculosis in those age groups, in order to prompt reflection on new approaches to the management of pediatric tuberculosis within the framework of the End TB Strategy.

Keywords: Tuberculosis, pulmonary/prevention & control; Mycobacterium tuberculosis; Lung diseases/etiology; Child; Adolescent.

Background: Bronchiectasis is a frequently found disease in medical practice in Brazil leading to significant morbidity and decrease in quality of life of the affected individuals. Objectives: To study diagnostic and therapeutic aspects in a series of hospitalized patients with bronchiectasis in a department of pulmonary diseases. Methods: Signs, symptoms, microbiological and radiographic data, and therapeutic results were studied in 170 hospitalized patients between 1978 and 2001 - females 62.4%, males 37.6%, and aged from 12 to 88 years (mean age 36.8 yrs). Previous history of pneumonia in childhood was detected in 52.5% of the patients, tuberculosis in 19.8%; 8.8% had bronchial asthma, and 2 had Kartagener's syndrome. Results: The most common symptoms were cough (100.0%), expectoration (96.0%) and pulmonary rales (66.0%). The pulmonary lesions were unilateral in 46.5% of the cases. Pneumococcus, H. influenzae or mixed flora were found in 85.0% of the examined sputa. All 170 patients received antibiotics and postural drainage, and 88 of them (younger and with a higher functional reserve) were also submitted to pulmonary resections (82 unilateral and 6 bilateral). Two deaths occurred, and repetitive hospitalizations were more frequent among the clinically treated patients. The follow up showed that most of the surgically treated patients had significant symptoms improvement and rarely needed to be re-hospitalized. Conclusions: In the majority of the patients, lung resection surgery improved permanently the prolonged bronchopulmonary symptoms of patients with bronchiectasis, differently from the patients who received only clinical treatment.

Keywords: Bronchiectasis/diagnosis. Bronchiectasis/therapy. Bronchiectasis/surgery. Bronchiectasis/complications. Tomography X-ray computed/methods. Inpatients. Retrospective studies.

Multiple respiratory abnormalities can be found in anxiety disorders, especially in panic disorder (PD). Individuals with PD experience unexpected panic attacks, characterized by anxiety and fear, resulting in a number of autonomic and respiratory symptoms. Respiratory stimulation is a common event during panic attacks. The respiratory abnormality most often reported in PD patients is increased CO2 sensitivity, which has given rise to the hypothesis of fundamental abnormalities in the physiological mechanisms that control breathing in PD. There is evidence that PD patients with dominant respiratory symptoms are more sensitive to respiratory tests than are those who do not manifest such symptoms, and that the former group constitutes a distinct subtype. Patients with PD tend to hyperventilate and to panic in response to respiratory stimulants such as CO2, triggering the activation of a hypersensitive fear network. Although respiratory physiology seems to remain normal in these subjects, recent evidence supports the idea that they present subclinical abnormalities in respiration and in other functions related to body homeostasis. The fear network, composed of the hippocampus, the medial prefrontal cortex, the amygdala and its brain stem projections, might be oversensitive in PD patients. This theory might explain why medication and cognitive-behavioral therapy are both clearly effective. Our aim was to review the relationship between respiration and PD, addressing the respiratory subtype of PD and the hyperventilation syndrome, with a focus on respiratory challenge tests, as well as on the current mechanistic concepts and the pharmacological implications of this relationship.

Keywords: Panic disorder; Anxiety; Respiration; Hyperventilation; Carbon dioxide.