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Control of ventilation depends on a brainstem neuronal network that controls activity of the motor neurons innervating the respiratory muscles. This network includes the pontine respiratory group and the dorsal and ventral respiratory groups in the medulla, which contain neurons that fire primarily during inspiration, post-inspiration, or expiration. The ventral respiratory group includes the pre-Bötzinger complex, which contains neurokinin-1 receptor immunoreactive neurons critical for respiratory rhythmogenesis. Structural and degenerative disorders affecting this network produce abnormalities of respiration, including sleep apnea and various patterns of dysrhythmic breathing, not infrequently associated with disturbances of cardiovagal and sympathetic vasomotor control. This emphasizes the important interactions between the respiratory and cardiovascular control networks in the medulla. Common disorders associated with impaired cardiorespiratory control include brainstem stroke or compression, syringobulbia, Chiari malformation, high cervical spinal cord injuries, and multiple system atrophy. This review focuses on the functional organization of the respiratory control network and common causes of impaired control of respiration.

The purpose of this review paper is to discuss: A) The differences in the nosological characteristics of this condition. Some authors only accept as primary pulmonary hypertension those patients without any other possible cause. They even exclude those with familiar pulmonary hypertension since its genetical etiology is now well established. It is more generally accepted that the very low incidence of pulmonary hypertension in conditions such as anorexigen use, portal hypertension or others, suggest the coincidence of a permissive genotype, susceptible phenotype (endothelial dysfunction) and a triggering factor. In such a way, pulmonary hypertension may be associated with apparently dissimilar conditions. B) The current interpretation of histologic lesions and their relationship with recent histochemical and immunological findings. The previously proposed hypothesis that some lesions are final and inactive results of prolonged hypertension is difficult to uphold since they were found only months after the clinical beginning of the disease. Moreover cells at the center of the plexiform lesion show histochemical activity patterns. It is also proposed that the anatomically inapparent endothelial dysfunction may be the original event. C) Proposed causal mechanisms such as down-regulation or even absence of K+ voltage channels of the pulmonary vascular smooth muscle cell. This finding would include primary pulmonary hypertension among the simultaneous "channel diseases". The data that justify the possible influence of serotonin plasma levels are also commented.

Asthma in the elderly is more severe and a decreased bronchodilating response has been suggested as a contributing factor. There is no agreement on the best way of expressing reversibility. The aim of this study was to evaluate bronchodilator response in elderly patients with asthma with different levels of airway obstruction and expressing reversibility by different indices. A total of 72 asthmatic patients were studied: (FEV1/FVC < 1.64 SEE below predicted). Two groups were considered: Group I: > or = 65 years (71.0 +/- 11.7 years; FEV1 54.0 +/- 16.7% of predicted) and Group II: < 40 years (23.0 +/- 7.7 years, FEV1 67.6 +/- 16.1%). Response to bronchodilators expressed as delta absolute, delta%predicted or delta%maximal was not different between the two groups. Reversibility expressed as delta%initial, however, was lower in younger patients (> 65 years: 22.2 +/- 16.6% vs 40 years: 11.8 +/- 9.9%, p = < 0.005). A covariance analysis was performed using baseline FEV1 as covariate and bronchodilator response was not different between the two groups. Neither delta absolute (r = 0.13, p = NS), delta%predicted (r = 0.06, p = NS) nor delta maximal (r = 0.09, p = NS) showed correlation with age. delta%initial showed weak but significant correlation with age (r = 0.28, p = < 0.05) and marked dependence on baseline FEV1 (r = 0.47, p = < 0.001). Bronchodilator reversibility in the elderly asthmatics is preserved. Expressing reversibility as delta%initial produces differences depending on baseline airway obstruction.

The advance which resulted in the mean survival increase from 50 to 75 years between 1920 and 1990 also provoked the rise in health care costs, and the so called "health crisis". In order to contain it, market tactics were put to action, health care was considered a commodity, patients "consumers" and hospitals or physicians "providers". Economists, accountants and business advisors in charge of "Health Maintenance Organizations" (HMO) started the very profitable activity of intervening between patients and physicians. Rationing, use of general practice guides, suboptimal treatments, risk avoidance and other market tactics changed the practice of a profession into a business enterprise. The HMO decides if, when, how and how much will be given to any "consumer". Use of technology more impersonal and easily administered is the leading feature of to-day's medicine over the intellectual activity of the physician who hears, understands, makes the physical examination, diagnosis and treatment. The increasing depreciation of his task obliges the physician to enlarge the number and decrease his communication with his patients. His fiduciary obligation is subordinated to market needs and his practice increasingly compromises his moral integrity. The HMO boasts of the quality of the service given, this is the timely use of to-day's appropriate resources. Nobody wants the 1950 car or medical practice. Tomorrow's practice however depends on increasing knowledge, that is, on research, an activity which is not the HMO object. The academic-medical center, the very place where the interaction of teaching and investigating promotes the excellence is discriminated by the HMO because of its compromise with fiduciary activity imposed by 2500 years of jewish-christian philosophy. The future of these institutions (state's Cinderella's) is progressively compromised; when we loose them how long will it take to recover them? The politicians are always ready to create new hospitals, after they are built consuming large amounts of money, they become disinterested. All hospitals in our country are completely active only 4 hours/day, their physicians travel afterwards to their diverse places of activity consuming much of their time in getting there and complying with the bureaucratic tasks imposed by HMO. In our country with 14% unemployment and 1/3 of the population without any health coverage, the institution of universal health insurance is mandatory. Preventive medicine is not effective for people who lack the means for adequate nutrition, education or transportation, they do not visit doctors or use medicines.

The aim of this study was to define the most useful index of expressing bronchodilator response and to distinguish between asthma and COPD. A prospective study was carried out of bronchodilator response in 142 asthmatics and 58 COPD patients in a university hospital. Reversibility was expressed as: 1. absolute change (delta abs); 2. % of initial (delta %init); 3. % of predicted (delta %pred) and 4. % of maximum possible response (delta %max). Dependence on forced expirations volume in 1 sec (FEV1) as % of predicted and sensitivity and specificity for diagnosis of asthma were established. A relationship between delta abs and initial FEV1 was not found in asthma (delta abs vs. % initial FEV1. r = 0.07) or COPD (r = 0.02). delta %pred did not show a correlation in asthma (r = 0.10) or COPD (r = 0.06). delta %init was dependent on the baseline value in asthma (r = 0.38, P < or = 0.001) but not in COPD (r = 0.18, P = n.s.). delta max was dependent in both. The combination of best sensitivity and specificity to separate asthma and COPD was obtained with delta abs (70.4 or 70.6%). The worst specificity for asthma diagnosis was obtained with delta %init (50%). The best likelihood ratios were obtained with delta abs and delta %pred and the worst likelihood ratio with delta %init. delta %init is not recommended as an index for differential diagnosis between asthma and COPD; 2) delta %init overscores bronchodilator response in patients with low FEV1. The independence of each bronchodilator response index should be verified in clinical trials for each selected sample.

Beta-agonists (beta 2) are the first treatment for acute asthma. Metered dose inhalers are preferable to nebulizers. During regular treatment, long-acting beta 2 show better results than sabutamol. Clinically relevant antiinflammatory activity has not been demonstrated. During regular treatment, tolerance to bronchodilator effects has not been detected but decrease of bronchoprotective effect is seen. These findings do not show clinical relevance. Short or long-acting beta 2 remain an appropriate and reliable treatment option for patients with asthma. Salmeterol and formoterol show similar action and adverse effects. The most rational treatment strategy seems to be: a) use inhaled steroids as the first and main regular treatment; b) when doses higher than 1,000-1,200 mcg/d of BCM or BUD are required, try long-acting beta-agonists; c) if that treatment is not effective enough, continue to increase inhaled steroid doses to identify patients responsive to higher doses.

In order to elucidate if the inspiratory effort sensation (IES) associated with carbon dioxide (CO2) is independent of the concomitant increase in the ventilation, we studied 23 normal resting volunteers (mean age 34 +/- 11 yr) during CO2 rebreathing. Our main goal was to compare the IES at the same ventilation level under hypercapnic and isocapnic conditions. The protocol included: (1) basal measurements (BASAL); (2) hypercapnic ventilation (HV); (3) screen copy of ventilatory pattern during hypercapnia (COPY); (4) screen copy at basal end-tidal (partial) carbon dioxide pressure (PETCO2) (ISO); and (5) recovery (REC). During HV, PETCO2 increased to 54.8 +/- 0.78 mm Hg (p < 0.001) and ventilation (VE) from 12.0 +/- 0.50 to 28.1 +/- 1.19 L/min (p < 0.001). Borg value increased from 0.11 +/- 0.06 to 3.4 +/- 0.23 (p < 0.001). These values were not different during HV and COPY. During ISO, PETCO2 was 40.2 +/- 0. 59 mm Hg (not significant [NS] from BASAL), while VE remained unchanged: 29.9 +/- 1.29 L/min (NS from HV and COPY). Interestingly, the Borg value during the ISO decreased to 1.86 +/- 0.28 (p < 0.001 compared with HV and COPY). The increased IES induced by hypercapnic ventilation was reduced at the same ventilation level during isocapnic conditions. We suggest that CO2 generates an IES independent of the concomitant increase in ventilation.

To examine the nature of asthma in the elderly, we compared older (group 1: 65 years or older, n = 50) with younger patients (group 2: <40 years, n = 99) and to determine the influence of long-standing disease, elderly asthmatics with early onset (group A: onset before 40, n = 22) were compared with patients developing symptoms later in their lives (group B: onset after 40, n = 22). Blood eosinophilia and IgE value >/=100 IU/l were more frequent in younger patients. Short symptom-free periods were more frequent among older asthmatics (78.5 vs. 45.4%, p < 0.001). Only 31.2% of older patients had only mild symptoms. Requirement of systemic steroids was higher in the elderly population. The worst FEV1 was lower in older patients (54.4 +/- 17.3 vs. 71.8 +/- 18.5%, p

A 27 year-old HIV+ patient was admitted to the hospital for probable Pneumocystis carinii pneumonia (PCP). He was severely dyspneic, with respiratory rate of 44 x min and accessory respiratory muscle contraction. The alveolar-arterial quotient was 0.35. Ventilation by BiPAP was applied during 12 hours. After BiPAP a/AO2 was O.42, with amelioration of dyspnea, decrease of respiratory rate (25 x min) and without using of accessory respiratory muscles. No complications occurred. At the end of hospital stay a/AO2 was 0.68. CPAP application but not BiPAP has been reported in PCP. Our patient showed evident improvement after BiPAP, suggesting that this method of ventilation is useful and should be incorporated to the routine management of these patients.

The influence of anesthesia, surgical procedure and special conditions of open-heart surgery upon respiratory function alterations is analyzed. Hypoxemia (present even in non-complicated open heart surgery) can be due to alveolar hypoventilation, ventilation-perfusion mismatch or shunt. The origin of atelectasias (present in 50-92% of patients) and pleural effusion (42-87%) is discussed. Phrenic nerve damage is usually secondary to thermal injury. Other less common complications are discussed. The influence of age, smoking and previous pulmonary diseases on respiratory complications is analyzed. Respiratory care after heart surgery (as time and requisites of extubations) and results of different methods (CPAP, PEEP, incentive inspirometry) are reviewed.

The reactive hemophagocytic syndrome is a condition characterized by systemic proliferation of benign hemophagocytic histiocytes, fever, cytopenia, abnormal liver function, and frequently coagulopathy and hepatosplenomegaly. Its occurrence has been documented in association with viral, bacterial, fungal and parasitic infections; a wide spectrum of malignant neoplasms; some miscellaneous disorders; and phenytoin. Disseminated strongyloidiasis is reported in a patients with systemic lupus erythematosus treated with corticosteroids in whom a reactive hemophagocytic syndrome developed and who finally died. This reactive hemophagocytic syndrome is reported for the first time in strongyloidiasis and may not have been recognized in former patients.

The objective of this study was to quantify the degree of disagreement in interpretation of spirometries and in the definition of the airway obstruction and response to bronchodilators (Bd) in different publications. Two surveys were carried out in which two groups of 15 pulmonologists were asked to identify in several spirometries the presence and degree of obstructive or restrictive defects (OD or RD), the response to Bd and whether the test was assessable or not. Three "problem' spirograms (PS) were included. For RD there was 76.1% of maximum agreement (MA). For OD the MA was 63.6%. Of the PS only 14% of the tests with a higher than 40% variation among the curves, 14% of those which did not include the graphic records and 33% of those with a considerably imperfect curve were considered nonassessable. The degree of disagreement for response to Bd was 24% (this implies 53.3% of possible maximal disagreement). Besides, every original article whose title or summary referred to "asthma', "chronic obstructive lung disease' or "chronic airflow obstruction' which was published from July 1991 to July 1993 in two respiratory medical journals (Chest and Thorax) was examined. Eleven different criteria to define obstruction were found. The most frequently used was FEV1/FVC < 70% (33.3%). Five different definitions of a positive response to Bd were found. The most popular was an increase in FEV1 > 15% of the initial value (76%). We conclude that there is very often disagreement in the interpretation of conventional spirometry. The definition of obstruction and reversibility in clinical trials is not uniform and great care must be taken when extrapolating the results from one publication to another since the composition of its samples could be substantially different.

Non-invasive mechanical ventilation is useful in order to delay or avoid endotracheal intubation. Continuous positive airway pressure (CPAP) is helpful for patients with decreased lung compliance, airways obstruction due to vocal cord paralysis or tracheobronchomalacia, presence of auto-PEEP (positive end-expiratory pressure) and as a weaning method. Non-invasive intermittent positive pressure ventilation (IPPV) is not very different from conventional mechanical ventilation except for the absence of an endotracheal tube. It is specially useful in patients with neuromuscular diseases or central hypoventilation. It has been also helpful for patients with decrease of lung compliance or COPD and as a weaning procedure. It may be applied with or without PEEP and by means of a bi-level IPPV system. All of these methods require cooperative patients and by means of a bi-level IPPV system. All of these methods require cooperative patients and they do not allow an adequate management of increased respiratory secretions. Non-invasive mechanical ventilation has the advantages of not showing complications associated to endotraqueal intubation and may be performed by means of less expensive equipment.

A 35-year-old man presented bilateral phrenic paralysis 7 months after radio-therapy for treatment of Hodgkin's lymphoma. Diaphragmatic dysfunction appeared after complete lymphoma remission and 4 months after chemotherapy discontinuation. There were no other potential causes. Idiopathic diaphragmatic paralysis was unlikely because it is usually unilateral. Radiation-induced neuropathy is well documented in other nerves as the brachial plexus. The timing, the applied dose and the location of the nerve within the radiation field are suggestive of radiation-induced phrenic nerve damage. Partial recovery was achieved after 4 years' follow-up.

Laryngeal wheezing caused by emotional stress is usually confused with that caused by bronchospasm and diagnosed as asthma, a well known emotionally influenced entity. Therefore, it is treated with bronchodilators, including corticosteroids, frequently resulting in a iatrogenic Cushing's syndrome. This case report concerns a patient initially considered to have bronchial asthma. Physiological and endoscopic studies allowed us to exclude this disease, as well as any organic obstruction of the upper and lower airway. Flow-volume curve showed that the tidal volume (VT) loop was displaced towards RV during the crisis and the expiratory flow of the VT reached the envelope of the maximal expiratory flow (Fig. 1). Direct larynx observation during fiberoptic bronchoscopy showed not only expiratory but also inspiratory vocal cords adduction. A diagnosis of emotional laryngeal wheezing was made. Excluding asthma, bronchodilators were progressively discontinued. She started to receive alprazolam and psychotherapy and during one year of follow-up she remained symptomless. Two mechanisms may be present in our patient: partial inspiratory adduction of vocal cords and breathing at low lung volume. Despite reported dissimilarities between these two mechanisms both seem to have a similar emotional origin.

Spirometry is the more frequently used method to estimate pulmonary function in the clinical laboratory. It is important to comply with technical requisites to approximate the real values sought as well as adequate interpretation of results. Recommendations are made to establish: 1--quality control 2--define abnormality 3--classify the change from normal and its degree 4--define reversibility. In relation to quality control several criteria are pointed out such as end of the test, back-extrapolation and extrapolated volume in order to delineate most common errors. Daily calibration is advised. Inspection of graphical records of the test is mandatory. The limitations to the common use of 80% of predicted values to establish abnormality is stressed. The reasons for employing 95% confidence limits are detailed. It is important to select the reference values equation (in view of the differences in predicted values). It is advisable to validate the selection with local population normal values. In relation to the definition of the defect as restrictive or obstructive, the limitations of vital capacity (VC) to establish restriction, when obstruction is also present, are defined. Also the limitations of maximal mid-expiratory flow 25-75 (FMF 25-75) as an isolated marker of obstruction. Finally the qualities of forced expiratory volume in 1 sec (VEF1) and the difficulties with other indicators (CVF, FMF 25-75, VEF1/CVF) to estimate reversibility after bronchodilators are evaluated. The value of different methods used to define reversibility (% of change in initial value, absolute change or % of predicted), is commented. Clinical spirometric studies in order to be valuable should be performed with the same technical rigour as any other more complex studies.

Vocal cord paralysis can produce extrathoracic airway obstruction with severe respiratory failure, post-surgical traumatism being the most frequent. Definitive treatment can require aritenoidectomy. For emergency treatment tracheal intubation of tracheotomy are frequently needed. We report a patient with acute post-surgical upper airway obstruction successfully treated with CPAP application through nasal mask. A 29 year-old female showed stridor and retraction of the supraclavicular, intercostal and epigastric region following an uncomplicated tracheal extubation immediately after surgery (radical thyroidectomy with nodal dissection). Pulsosaturometry showed O2 desaturation despite high flow O2 administration. She received intravenous steroids and O2 through intermittent positive pressure by nasal mask (manual resuscitator) increasing SpO2 to 90%. Laringoscopy showed both vocal cords fixed at medium line. CPAP through a nasal mask was initiated with a 5 cm H2O pressure and high FIO2. Immediately afterwards, dyspnea, stridor, supraclavicular retraction and respiratory accessory muscles use disappeared. Heart rate decreased (120 to 92 x min.) and SpO2 increased to 99%. Arterial blood gases did not show hypercapnia. Dyspnea and physical signs of upper airway obstruction appeared immediately after interrupting CPAP application, with a marked decrease in SpO2. So the mask was reinstalled keeping the same pressure level during 18 hs. The procedure was well tolerated. There were no local or hemodynamic complications. CPAP was progressively discontinued.(ABSTRACT TRUNCATED AT 250 WORDS)

A 62 year-old woman with a bilateral carotid body paraganglioma presented, 2 years after the removal of the right one, with signs of right-heart failure. Hypoxemia, hypercapnia, polycythemia and pulmonary hypertension with normal ventilatory capacity were found. Central alveolar hypoventilation was diagnosed on the basis of absence of ventilatory response and sensation of provoked hypercapnia, prolonged breath-holding time and correction of hypercapnia by voluntary ventilation. Progesterone (200 mg/d during 3 weeks) or naloxone did not improve either arterial blood gases (ABG) or the P 0.1/PCO2 curve. Hypoxemia and hypercapnia were not corrected during metabolic acidosis provoked by acetazolamide (250 mg/d). Nasal CPAP did not control hypoventilation periods. Mechanical ventilation was initiated with negative pressure (NPV) through a poncho. The patient presented severe discomfort with NPV and obstructive apneas were verified during it. She refused to continue NPV. Mechanical ventilation was initiated with positive intermittent pressure (IPPV) through a nasal mask. The patient had excellent tolerance to the procedure. SpO2 during IPPV was always higher than 95%. During sleep induction (under IPPV), respiration in phase with the ventilator 1: 1 was observed; instead, during consolidated sleep there was a complete dependence of the ventilator with apnea for over 2 min when IPPV was interrupted (Fig. 1). After 2 months of treatment, a relief of right ventricular failure occurred and hematocrit fell to 39%. There was an improvement of day-time ABG (Table I). The P. 0.1/PaCO2 curve 3 months after IPPV was the same as the previous one (Fig. 2). The patient has been for 18 months on home ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

The response to bronchodilators was evaluated in 295 spirometric studies performed in 82 patients with asthma (defined according to ATS criteria, with at least one previous basal test with 20% of change in FEV1 compared with the present test). The response to bronchodilators (Bd) was measured fifteen minutes after the inhalation of salbutamol 200 mcg by metered dose inhaler and in the absence of Bd inhalation in the previous six hours. Sixty-eight spirometries (23%) were classified as with no response to Bd (NR) (absolute delta FEVI[delta abs] < 200 ml, delta FEV1 in percentage of initial FEVI[delta%] < 15%, delta FVC in percentage of the initial [delta FVC] < 15% and delta FEF 25-75% in percentage of the initial [delta FEF] < 25%). Only 23% (n = 16) of them showed an initial FEVI greater than 80% of predicted. In this group 4 tests (5% of NR, 1.3% of the whole) showed delta abs > 150 ml and 1 (1.5% of NR, 0.3% of whole) delta% > 12%. Thirty six percent of the whole population (n = 109) would have been classified as NR taking as unique criterion delta VEF1% < 15%, 24 of which (8% of whole population) showed delta VEF1 abs > 200 ml (initial FEVI 2.48 +/- 0.60 l) (Table 3). On the other hand, 94 spirometries (31% of the whole) would have been classified as NR taking as unique criterion delta abs < 200 ml. twelve of which (4% of the whole) showed delta% > 15% (initial FEVI 0.81 +/- 0.171) (Table 2).(ABSTRACT TRUNCATED AT 250 WORDS)

A 36 year-old non-smoker woman was admitted because of a rapidly growing mass at the left hilum. Fiberoptic bronchoscopy did not show any abnormality. A percutaneous Rotex needle biopsy and a cutting needle biopsy showed atypical cells suggestive of an anaplastic tumor, possibly a sarcoma. A thoracotomy biopsy demonstrated nodal and pulmonary involvement by Hodgkin lymphoma (nodular-sclerosis form) and pulmonary TBC (granulomas with caseum and acid fast bacilli (AFB)). The patient started treatment with isoniazid, rifampin and pirazynamide and then she received chemotherapy and radiotherapy. One year later her chest and abdominal CT were normal. Twelve months after that she developed severe dyspnea with a chest x-ray film with interstitial infiltrates and a mass at the left-hilum. She worsened quickly and died. At autopsy no evidence of active TBC was found and extensive involvement by lymphoma was demonstrated. The diagnosis in this patient was not obtained by clinical-radiological signs or by non-invasive tests but only by surgical biopsy. The association between neoplasm and TBC is well known, but now is very rare. In Argentina TBC prevalence in lymphomas is 1.2% (higher than control population). TBC diagnosis can occasionally be difficult. In most of undiagnosed patients TBC is the main contributor to death. In this patient the mediastinopulmonary mass was adequately diagnosed only after an open biopsy which showed it to be caused by two coexistent diseases, previously unsuspected and both amenable of effective treatment. This case shows the heterogeneity of TBC presentation and stresses the need to consider it in each non-defined mediastino-pulmonary lesion in countries where TBC is highly prevalent.(ABSTRACT TRUNCATED AT 250 WORDS)

Several meetings of chest specialists were held in order to update basic knowledge on Chronic Obstructive Pulmonary Disease (COPD) and to establish guidelines regarding its prevention and treatment. This Consensus was prompted by the important morbidity and mortality due to COPD. Pulmonary emphysema, chronic bronchitis and asthma may evolve into COPD when developing chronic, persistent, non reversible airflow obstruction. Its pathologic features, physiopathology, pulmonary function derangements and clinico-radiological picture are summarized. Early detection and prevention accomplished through smoking cessation are essential to stop health damage due to this condition. Strategies directed to smoking cessation are described. Once COPD is established, inhaled bronchodilators (IB)--anticholinergics, beta-2 agonists or both--might be useful. Teophylline is indicated additionally when no improvement is obtained with IB. Inhaled steroids (IE) may stop progression of airways obstruction; they are recommended in patients who remain symttomatic and/or with severe airflow obstruction (FEV1 less than 50% predicted) despite treatment with beta-2 adrenergics and teophylline. Vaccination against influenza and pneumococcal pneumonia is suggested. Other medications (antibiotics, psychoactive drugs, alpha-1 antitrypsine, respiratory stimulants) or surgical interventions, including lung transplantation, might be of help in certain circumstances. In patients with physiotherapy, supplementary nutrition, muscle retraining, prolonged oxygen therapy and, eventually, noninvasive mechanical ventilation might improve survival and quality of life. Acute decompensations leading to respiratory failure should be promptly detected and treated with oxygen, IB, teophylline, corticosteroids, antibiotics and, eventually, mechanical ventilation. The main role of public education in disease prevention is emphasized. Moreover, patient and family education is essential for adequate treatment of COPD.

Severe inspiratory elastic load terminated by respiratory arrest (RA) was studied in 24 anesthetized dogs (group 1, normal: n = 14; group 2, vagotomized: n = 10). The peripheral and central components of the decrease in diaphragmatic force generation and the events preceding RA were studied. We measured stimulated tetanic transdiaphragmatic pressure (Pdi), single twitch compound action potentials, integrated diaphragmatic electromyographic activity (iEMGdi), respiratory frequency (f), inspiratory time, inspiratory drive, overall diaphragmatic activation, and Pdi single twitch superimposed over peak Pdi. Imposed target pressure was -68.8 +/- 4.37 cmH2O for group 1 and -70.9 +/- 4.19 cmH2O for group 2, and the tension-time index of the diaphragm was the same for both groups (0.22 +/- 0.010). During load, 1) f increased in group 1 from 25.4 +/- 1.33 to 41.3 +/- 4.66 cycles/min, and tachypnea was prevented by vagotomy; 2) twitch occlusion persisted until RA and compound action potentials did not change; 3) iEMGdi and inspiratory drive increased and remained high until RA; 4) overall diaphragmatic activation increased 514 (group 1) and 260% (group 2) and then decreased to 228% of the basal value 10 s before RA in group 1 because of a fall in f; and 5) after RA, Pdi stimulated at 60 Hz fell to 39 (group 1; P < 0.0025) and 51% (group 2; NS with group 1) of the basal value. In summary, 1) peripheral fatigue developed without transmission failure; 2) diaphragmatic activation remained maximal until RA; 3) the fall in f appeared as a preterminal event only in group 1; and 4) vagus nerves are necessary for load-induced tachypnea.

A 62-year-old woman with a bilateral carotid body paraganglioma presented, 2 years after the removal of the right one, with signs of right-heart failure. Hypoxemia, hypercapnia, polycythemia and pulmonary hypertension with normal ventilatory capacity were found. Central alveolar hypoventilation was diagnosed on the basis of absence of ventilatory response and sensation to provoked hypercapnia, prolonged breath-holding time and correction of hypercapnia by voluntary hyperventilation.

A group of pulmonologists from different sites of Argentina convened to establish consensus guidelines for treatment of acute and chronic bronchial asthma. General acceptance that in fatal asthma diagnosis and hospital admission are usually too late and treatment insufficient prompted the need for this meeting. The purpose of treatment was devised to keep the patient symptomless, decrease frequency of exacerbations and the risk of severe attacks. Peak expiratory flow rate (PEFR) measurement in all patients was decided. inhalation of anti-inflammatory drugs (corticosteroids, CE, and/or disodium cromoglycate, DSG, in those younger than 20 years) was established as first line of treatment. Inhaled CE (even in high doses such as 2 mg/day) do not provoke significant adverse systemic effects (immune depression, Cushing syndrome, hyperglycemia in diabetics or osteopenia). Secondary local adverse effects are however frequent: oral and pharyngeal candidiasis and dysphonia. It is advisable considering present evidence, that bronchodilators (Bd) be used preferentially on demand. On account of small bronchodilator effect and frequent secondary adverse effects, use of theophylline should be limited to patients not adequately responsive to anti-inflammatory drugs in high dosage. Immunotherapy is not useful in asthma. Four clinical levels were defined in chronic asthma considering severity of dyspnea, frequency of nocturnal bronchial obstruction, levels of PEFR and amount of required Bd. Guidelines of treatment were established for each clinical level considering increasing dosage of CGS, inhaled CE (up to 2 mg/day) and regular administration of Bd. Indications for systemic CE administration were also established. Three levels of acute asthma (sudden worsening of symptoms) were accepted based on clinical evidence and PEFR values. Treatment was quantitatively adjusted to severity. Criteria for hospital admission either in emergency or intensive care areas and treatment procedures were established.

Pulmonary arterial hypertension (PAH) and cor pulmonale were found in a patient with paroxysmal nocturnal hemoglobinuria (PNH). Autopsy revealed widespread thromboses in pulmonary microvasculature. Vascular thromboses attributed to hypercoagulability have been found in PNH in many organs, including the lungs. PAH has not been reported, however. This disease should then be considered a rare cause of PAH.

Pulmonary arterial hypertension and compulmonale were found in a woman with inactive systemic lupus erythematosus (SLE). The patient died of right heart failure 5 years later. Postmortem study showed SLE reparative lesions, plexogenic arteriopathy and vasculitis in the lung vessels. Since no active SLE was found, the pulmonary vasculitis was attributed to plexogenic arteriopathy.