Bronchiolar disorders

Bronchiolar abnormalities are relatively common and occur in a variety of clinical settings. Various histopathologic patterns of bronchiolar injury have been described and have led to confusing nomenclature with redundant and overlapping terms. Some histopathologic patterns of bronchiolar disease may be relatively unique to a specific clinical context but others are nonspecific with respect to either etiology or pathogenesis. Herein, we present a scheme separating (1) those disorders in which the bronchiolar disease is the predominant abnormality (primary bronchiolar disorders) from (2) parenchymal disorders with prominent bronchiolar involvement and (3) bronchiolar involvement in large airway diseases. Primary bronchiolar disorders include constrictive bronchiolitis (obliterative bronchiolitis, bronchiolitis obliterans), acute bronchiolitis, diffuse panbronchiolitis, respiratory bronchiolitis, mineral dust airway disease, follicular bronchiolitis, and a few other rare variants. Prominent bronchiolar involvement may be seen in several interstitial lung diseases, including hypersensitivity pneumonitis, respiratory bronchiolitis-associated interstitial lung disease, cryptogenic organizing pneumonia (idiopathic bronchiolitis obliterans organizing pneumonia), and pulmonary Langerhans' cell histiocytosis. Large airway diseases that commonly involve bronchioles include bronchiectasis, asthma, and chronic obstructive pulmonary disease. The clinical relevance of a bronchiolar lesion is best determined by identifying the underlying histopathologic pattern and assessing the correlative clinico-physiologic-radiologic context.

Low birth weight for gestation and airway function in infancy: exploring the fetal origins hypothesis

BACKGROUND

Poor fetal growth has been associated with impaired airway function in adult life, but evidence linking birth weight and airway function in early childhood is sparse. We examined the hypothesis that low birth weight for gestation is associated with impaired airway function shortly after birth and that this is independent of impaired postnatal somatic growth.

METHODS

Airway function was measured using the raised volume technique in healthy white infants of low (< or =10th centile) or appropriate (> or =20th centile) birth weight for gestation and was expressed as forced expiratory volume in 0.4 s (FEV0.4), forced vital capacity (FVC), and the maximal expired flow at 25% of forced vital capacity (MEF25). Infant length and weight, maternal height and weight, maternal report of smoking prenatally and postnatally, and parental occupation were recorded.

RESULTS

Mothers of low birth weight for gestation infants (n=98) were lighter, shorter, and more likely to smoke and have partners in manual occupations. At 6 weeks their infants remained lighter and shorter than those of appropriate birth weight (n=136). FEV0.4, FVC, and MEF25 were reduced in infants of low birth weight for gestation, in those whose mothers smoked in pregnancy, or who were in manual occupations. After adjusting for relevant maternal and infant characteristics, infants in the low birth weight for gestation group experienced a mean reduction of 11 ml in FEV0.4 (95% CI 4 to 18; p=0.002), of 12 ml in FVC (95% CI 4 to 19; p=0.004), and of 28 ml/s in MEF25 (95% CI 7 to 48; p=0.03).

CONCLUSIONS

Airway function is diminished in early postnatal life as a consequence of a complex causal pathway which includes social disadvantage as indicated by maternal social class, smoking and height, birth weight as a proximal and related consequence of these factors, and genetic predisposition to asthma. Further work is needed to establish the relevance of these findings to subsequent airway growth and development in later infancy and early childhood.

Endobronchial tuberculosis

Endobronchial tuberculosis (EBTB) is defined as tuberculous infection of the tracheobronchial tree with microbial and histopathological evidence. It is seen in 10-40% of patients with active pulmonary tuberculosis. More than 90% of the patients with EBTB have some degree of bronchial stenosis. Ten to 20 percent have normal chest radiograph. Therefore, a clear chest radiograph does not exclude the diagnosis of EBTB. Bronchoscopic sampling has been the key to the diagnosis producing more than 90% yield on smear as well as on culture. Bronchoscopy and computed tomography are the methods of choice for accurate diagnosis of bronchial involvement and assessment for the surgical interventions. Characteristic HRCT findings of FBTB are patchy asymmetric centrilobular nodules and branching lines (tree-in-bud appearance). Early supervised antituberculosis therapy results in minimal structural and functional residua. Corticosteroid therapy may not influence the outcome of endobronchial tuberculosis. Early diagnosis and prompt treatment, before the development of fibrosis is important to prevent complications of endobronchial tuberculosis, such as bronchostenosis.

Application of high-density DNA microarray to study smoke- and hydrogen peroxide-induced injury and repair in human bronchial epithelial cells

Recent advances in high-density DNA microarray technique allow the possibility to analyze thousands of genes simultaneously for their differential gene expression patterns in various biologic processes. Through clustering analysis and pattern recognition, the significance of these differentially expressed genes can be recognized and correlated with the biologic events that may take place inside the cell and tissue. High-density DNA microarray nylon membranes were used to explore gene expression and regulation associated with smoke- and hydrogen peroxide-induced injury and repair in differentiated human bronchial epithelial cells in vitro. At least three phases of change in gene expression could be recognized. The first phase seems to be an immediate event in response to oxidant injury. This phase includes the induction of bcl-2 and mdm2 genes that are involved in the regulation of apoptosis, and the mitogen-activated protein kinase phosphatase 1 that functions as a regulator for various mitogen-activated protein kinase activities. The second phase, usually 5 h later, includes the induction of various stress proteins and ubiquitin, which are important in providing the chaperone mechanism and the turnover of damaged macromolecules. The third phase, which is 5 to 10 h later, includes the induction of genes that seem to be involved in reducing oxidative stress by metabolizing the cellular level of reactive oxygen species. In this phase, enzymes associated with tissue and cell remodeling are also elevated. These results demonstrated a complex gene expression array by bronchial epithelial cells in response to a single insult of oxidants that are relevant to environmental pollutants.

[The sinobronchial syndrome. Assessment of the influence of the upper on the lower airway diseases]

Epidemiological and clinical data are discussed dealing with a possible influence of inflammatory changes of the nasal and especially the paranasal tissue on lower airway disease like asthma, the so-called "sinobronchial syndrome". Even though there is clear evidence of an association of the upper with the lower airway diseases, a causal relationship and a possible work of action are still up for discussion. The literature has been reviewed, and different theories are discussed. Generally speaking, a branch of differently accentuated mechanisms seems to play a role.

Relation between structure, function, and imaging in a three-dimensional model of the lung

Previous studies have reported morphometric models to predict function relations in the lung. These models, however, are not anatomically explicit. We have advanced a three-dimensional airway tree model to relate dynamic lung function to alterations in structure, particularly when constriction patterns are imposed heterogeneously inspecific anatomic locations. First we predicted the sensitivity of dynamic lung resistance and elastance (RL and EL) to explicit forms of potential constriction patterns. Simulations show that severe and heterogeneous peripheral airway constriction confined to a single region in the lung (apex, mid, or base) will not produce substantial alterations in whole lung properties as measured from the airway opening. Conversely, when measured RL and EL are abnormal, it is likely that significant (but not necessarily homogeneous) constriction has occurred throughout the entire airway tree. We also introduce the concept of image-assisted modeling. Here positron emission tomographic imaging data sensitive to ventilation heterogeneity is synthesized with RL and EL data to help identify which airway constriction conditions could be consistent with both data sets. An ultimate goal would be personalized predictions.

Bronchodilation in infants with malacia or recurrent wheeze

BACKGROUND

Controversy remains regarding the effectiveness of bronchodilators in wheezy infants.

AIMS

To assess the effect of inhaled beta(2) agonists on lung function in infants with malacia or recurrent wheeze, and to determine whether a negative effect of beta(2) agonists on forced expiratory flow (V'(maxFRC)) is more pronounced in infants with airway malacia, compared to infants with wheeze.

METHODS

We retrospectively analysed lung function data of 27 infants: eight with malacia, 19 with recurrent wheeze. Mean (SD) age was 51 (18) weeks. Mean V'(maxFRC) (in Z score) was assessed before and after inhalation of beta(2) agonists.

RESULTS

Baseline V'(maxFRC) was below reference values for both groups. Following inhalation of beta(2) agonists the mean (95% CI) change in mean V'(maxFRC) in Z scores was -0.10 (-0.26 to 0.05) and -0.33 (-0.55 to -0.11) for the malacia and wheeze group, respectively.

CONCLUSIONS

In infants with wheeze, inhaled beta(2) agonists caused a significant reduction in mean V'(maxFRC). Infants with malacia were not more likely to worsen after beta(2) agonists than were infants with recurrent wheeze.

Tracheomalacia and bronchomalacia in children: pathophysiology, assessment, treatment and anaesthesia management

Tracheomalacia and bronchomalacia are becoming increasingly well recognized. Although pathologically benign conditions, they are responsible for considerable morbidity, occasional mortality and significant difficulties in the operating theatre and intensive care unit. We performed an extensive literature search to identify causal associations, methods of clinical and investigative assessment, treatment modalities and anaesthetic experience with these conditions.

Resolution of native lung pneumothorax by insertion of a nitinol stent for bronchostenosis in the transplanted lung

Following single lung transplantation, the native lung remains a potential source of morbidity from spontaneous pneumothorax, hyperinflation, bacterial and fungal infection and malignancy. The case of a single lung transplant recipient for idiopathic pulmonary fibrosis who developed a recurrent, non-resolving, spontaneous multiloculated pneumothorax in the native lung following thoracoscopic talc pleurodesis is reported. The pneumothorax ultimately resolved following insertion of a nitinol stent for coexisting bronchostenosis in the transplanted lung. In a single lung transplantation recipient in whom a native lung pneumothorax reoccurs or persists despite appropriate initial management, it may be useful to undertake bronchoscopy to exclude the possibility of bronchostenosis in the transplanted lung.

Effects of bronchial obstruction on lower esophageal sphincter motility and gastroesophageal reflux in patients with asthma

The relationship between gastroesophageal reflux and asthma remains unclear. The aim of this study was to analyze the effect of bronchial obstruction on lower esophageal sphincter (LES) motility and reflux in patients with asthma. LES motility and esophageal pH were assessed in eight subjects with intermittent asthma and eight healthy volunteers during three consecutive 30-minute periods: baseline, methacholine-induced bronchospasm, and after inhalation of the beta2-agonist salbutamol. Healthy subjects inhaled 2 mg of methacholine, whereas subjects with asthma inhaled the dose of methacholine causing a 15% fall in FEV(1), as determined by a previous methacholine challenge. LES motility, esophageal pH, and FEV(1) were not significantly different between the three periods in healthy subjects. In patients with asthma, methacholine induced a 21.9 +/- 2.6% decrease in FEV(1) and a concomitant increase in the rate of transient LES relaxation (TLESR) and reflux episodes. Inhalation of salbutamol decreased the rate of TLESRs but not the number of reflux episodes. We conclude that in patients with asthma, methacholine-induced bronchospasm increases the rate of TLESR and the number of reflux episodes. These results support the belief that, in asthma, bronchial obstruction may be responsible for reflux or may aggravate reflux through a mechanism that remains to be further clarified.

Broncholithiasis: a case report

A case is reported of broncholithiasis in a 29-year-old female factory worker presenting with cough and lithoptysis. Broncholithiasis is a rare disorder characterized by calcified perihilar and mediastinal lymph nodes eroding into the tracheobronchial tree. Although cough, hemoptysis, lithoptysis, pneumonia and bronchoesophageal fistula formation have been reported, broncholithiasis may also result in potentially life-threatening conditions such as airway obstruction from endobronchial polypoid granulation masses, and massive hemorrhage from an aorto-tracheal fistula or erosion of a pulmonary artery branch.

Angiogenesis in paediatric airway disease

A number of characteristic changes occur in the bronchial wall in paediatric airway diseases. The process of remodelling is usually associated with specific changes to the vasculature, resulting in an increase in vessel numbers, vasodilatation, vessel leakage and cellular margination with transmigration to target tissues. This combined action in conditions such as asthma, cystic fibrosis and bronchiolitis lead to airway wall thickening and reduced airflow. Each component of the vascular response has been shown to be controlled by a range of inflammatory mediators and growth factors. These factors are regulated by a complex process involving gene expression, transcription and translation at the molecular level, protein release, binding to matrix elements and receptors on endothelial cells, then the endothelial response itself. A number of commonly used airway medications are potentially capable of modulating the vascular response to inflammatory stimuli. New therapies may be able to improve airflow through better regulation of vessel growth, dilatation and leakage in the airway wall.

[Results of bronchoplasty by fiberoptic bronchoscopic balloon dilatation in the management of proximal benign tracheobronchial stenosis]

OBJECTIVE

To assess the effect and safety of balloon dilatation through fiberoptic bronchoscopy in the management of benign tracheobronchial stenosis.

METHODS

Thirty-seven patients with proximal benign tracheobronchial stenosis were treated by balloon dilatation through flexible fiberoptic bronchoscopy. A fiberoptic bronchoscope was inserted, a balloon catheter was sent to the stenotic segment from the working channel and positioned in the stenotic bronchus. Under direct visualization, the balloon was inflated for 1 min to 3 min. Repeat inflation-deflation cycles were done if airway narrowing remained after the initial operation. Before the procedure and immediately after the last operation, airway diameters, dyspnea index and complications were evaluated in all of the patients and FEV(1) was tested in 26 of the 37 patients.

RESULTS

One to 6 operations (2.4 +/- 1.1, approximately x +/- s) were required to achieve satisfactory dilatation. After high-pressure balloon dilatation, the average airway diameter increased from (2.6 +/- 1.2) mm to (6.9 +/- 1.8) mm (P < 0.01). Dyspnea index decreased from 2.0 +/- 0.8 to 0.7 +/- 0.6 (P < 0.01). FEV(1) was increased from (1.3 +/- 0.6) L to (1.8 +/- 1.0) L (P < 0.01). No severe complications were found in these patients

CONCLUSION

Bronchoplasty by high-pressure balloon dilatation through flexible fiberoptic bronchoscopy is a simple but effective and safe method to treat proximal benign tracheobronchial stenosis.

Diseases of the small airways

The respiratory tree is involved in a wide range of pathological conditions. The consequences of these processes vary from negligible to severe airflow obstruction with resultant hypoxia and respiratory failure. Although almost all of the processes described herein are associated with activation of cytokines, ecosanoids, or peptide hormones, detailed descriptions of these interactions are beyond the scope of this article.

Benign tracheobronchial stenoses: changes in short-term and long-term pulmonary function testing after expandable metallic stent placement

PURPOSE

To determine the short- and long-term improvement in airflow dynamics in patients undergoing tracheobronchial stent placement for benign airway stenoses.

METHODS

Twenty-two patients underwent 34 tracheal and/or bronchial stent placement procedures for benign airway stenoses and had the results of pulmonary function tests available. Stent placement indications included bronchomalacia after lung transplantation (n = 11), postintubation stenoses (n = 6), relapsing polychondritis (n = 2), and 1 each of tracheomalacia, tracheal compression, and histoplasmosis. Six patients underwent more than one stent placement procedure (range: 2-7 procedures). The mean forced expiratory volume in one second (FEV(1) ), forced expiratory flow rate in the midportion of the forced vital capacity curve (FEF(25-75) ), forced vital capacity, and peak flow (PF) rate obtained before stent placement were compared with those immediately after stent placement and with those measurements most remote from stent placement using the paired two-tailed test.

RESULTS

All patients reported improved respiratory function immediately after stent placement. The mean FEV(1), FEF(25-75), and PF rate improved significantly (p < 0.001, p = 0.002, and p = 0.009, respectively) after stent placement. On long-term follow-up averaging 15 months after stent placement, these parameters declined despite patients' subjective sense of improvement. Segregating the population into transplant and nontransplant airway stenosis etiologies, however, FEF(25-75) and PF rate remained significantly improved (p = 0.045, p = 0.027, respectively), over the long term for the latter. FEV increased after subsequent stent placements for patients receiving multiple stents.

CONCLUSION

Stent placement for benign tracheobronchial stenoses provides significant immediate improvement in airflow dynamics. Long-term improvement in airflow obstruction may be expected, and additional stent placements may further improve pulmonary function.

Endobronchial hamartoma

OBJECTIVES

To describe clinical, endoscopic, radiographic, and follow-up characteristics of a series of patients in whom endobronchial hamartoma (EH) had been diagnosed.

METHODS

Retrospective study of all cases of hamartoma diagnosed by bronchial biopsy between 1974 and 1997 in a tertiary referral hospital in Madrid, Spain.

RESULTS

EH was diagnosed 47 patients during the study period. Four patients were excluded from the study because no clinical history was available. We analyzed the cases of 43 patients (37 men and 6 women), with a mean (+/- SD) age of 62 +/- 12 years. Seven patients had a concurrent lung neoplasm, and the EH was an incidental endoscopic finding. Among the other 36 patients, 31 had a new onset of respiratory symptoms, most commonly, recurrent respiratory infections in 16 patients (44%) and hemoptysis in a further 12 patients (33.4%). Chest radiograph findings were abnormal in 38 of 43 patients. At bronchoscopy, the lesions were equally distributed throughout the right and left lungs with no clear lobar predilection. Endobronchial obstruction was evident in 26 patients (72.2%) without concurrent neoplasm, 17 of whom underwent resection with a rigid bronchoscope and laser, with total resolution in 13 patients. Partial resolution was achieved in four patients, two of whom needed a second endoscopic procedure. Five patients were treated with open lung surgery. Clinical and endoscopic follow-up was performed in 23 patients at 1 to 73 months (mean, 17 months), and recurrence was found in 4 patients.

CONCLUSION

EH frequently produces respiratory complaints and radiographic abnormalities. Patients with endobronchial obstructions had satisfactory responses to endoscopic therapy.

Influence of zafirlukast and loratadine on exercise-induced bronchoconstriction

BACKGROUND

Airway obstruction induced by physical exercise is a common feature in asthma, and conventional treatments do not offer optimal protection. There is thus a need for additional therapies for optimal control of exercise-induced bronchoconstriction (EIB).

OBJECTIVE

The influence of treatment with the antihistamine loratadine and the antileukotriene zafirlukast alone and in combination on EIB was investigated. This combination has previously shown beneficial additive effects in allergen-induced bronchoconstriction.

METHODS

In a double-blind cross-over study loratadine (10 mg twice daily) and zafirlukast (80 mg twice daily) were evaluated alone and in combination in 16 nonsmoking patients with mild asthma, previously documented EIB, and airways hyperresponsiveness to histamine.

RESULTS

The mean +/- SE maximum decrease in FEV1 after a standardized exercise provocation was 21.6% +/- 3% after placebo, 22.8% +/- 3% after loratadine, 13.9% +/- 2% after zafirlukast (P <.05 vs placebo), and 10.3% +/- 2% after the combination of loratadine and zafirlukast (P <.05 vs placebo). Expressed as the area under the FEV1 percentage change versus time curve, the mean protection produced by zafirlukast and the combination of zafirlukast and loratadine was 57% and 65%, respectively, whereas loratadine alone had no significant protective effect. There was also no significant difference between the effect of zafirlukast alone or in combination with loratadine.

CONCLUSION

The study confirmed the beneficial effect of a leukotriene receptor antagonist in EIB but failed to obtain evidence that H1-receptor antagonism alone or together with the cysteinyl-leukotriene 1 receptor antagonist zafirlukast offers a protective effect.

Low-volume ventilation causes peripheral airway injury and increased airway resistance in normal rabbits

Lung mechanics and morphometry of 10 normal open-chest rabbits (group A), mechanically ventilated (MV) with physiological tidal volumes (8-12 ml/kg), at zero end-expiratory pressure (ZEEP), for 3-4 h, were compared with those of five rabbits (group B) after 3-4 h of MV with a positive end-expiratory pressure (PEEP) of 2.3 cmH(2)O. Relative to initial MV on PEEP, MV on ZEEP caused a progressive increase in quasi-static elastance (+36%) and airway (Rint; +71%) and viscoelastic resistance (+29%), with no change in the viscoelastic time constant. After restoration of PEEP, quasi-static elastance and viscoelastic resistance returned to control levels, whereas Rint remained elevated (+22%). On PEEP, MV had no effect on lung mechanics. Gas exchange on PEEP was equally preserved in groups A and B, and the lung wet-to-dry ratios were normal. Both groups had normal alveolar morphology, whereas only group A had injured respiratory and membranous bronchioles. In conclusion, prolonged MV on ZEEP induces histological evidence of peripheral airway injury with a concurrent increase in Rint, which persists after restoration of normal end-expiratory volumes. This is probably due to cyclic opening and closing of peripheral airways on ZEEP.

Airway hyperresponsiveness in transgenic mice overexpressing platelet activating factor receptor is mediated by an atropine-sensitive pathway

Platelet activating factor (PAF) is a potent mediator potentially involved in the pathogenesis of inflammatory disorders, including bronchial asthma. Recently, transgenic mice overexpressing the PAF receptor (PAFR) gene have been established, and exhibit bronchial hyperresponsiveness, one of the cardinal features of asthma. To elucidate the molecular and pathophysiologic mechanisms underlying PAF-associated bronchial hyperreactivity, we studied airway responsiveness to methacholine (MCh) and serotonin (5-hydroxytryptamine; 5-HT) in PAFR-transgenic mice. In addition, we examined the role of the muscarinic receptor in PAF-induced responses and the binding activities of the muscarinic receptor. The PAFR-transgenic mice exhibited hyperresponsiveness to MCh and PAF; however, no significant differences in 5-HT responsiveness were observed between the control and PAFR-transgenic mice. The administration of atropine significantly blocked PAF-induced responses in PAFR-transgenic mice. There were no differences between the two phenotypes in the binding activities of muscarinic receptor. Morphometric analyses demonstrated that PAFR overexpression did not affect airway structure. These findings suggest that the muscarinic pathway may have a key role in airway hyperresponsiveness associated with PAFR gene overexpression. More generally, PAFR-transgenic mice may provide appropriate models for study of the molecular mechanisms underlying PAF-associated diseases.

Mouse strain modulates the role of the ciliated cell in acute tracheobronchial airway injury-distal airways

Understanding cellular repair mechanisms in vivo has been advanced through the use of well-defined injury and repair models and their application to knockout and transgenic animals, primarily mice generated in a variety of background strains. However, little is known concerning the effect that mouse strain itself has on the interpretation and comparability of observations when the strain used for genetic manipulation is not the strain used to develop the model. We compared acute bronchiolar injury and repair in three strains of mice used in knockout mouse development (C57BL/6, 129/TerSv, and 129/SvEv) to the model strain (Swiss Webster) after treatment with the same dose of naphthalene and sacrificed at 1, 2, 4, 7, and 14 days after treatment. Extent of Clara cell toxicity and exfoliation was identical in the distal airways of all strains. There were significant strain-related differences in ciliated cell squamation, initiation and duration of proliferation, epithelial differentiation, and time to completion of epithelial repair. We conclude that ciliated cells play a prominent role in repair of distal airway injury, but that all phases of the repair process differ by strain. In addition, our findings reinforce that control animals must be of the same strain, ideally litter mates, when transgenic or knockout mice are used for the study of airway repair processes and mechanisms.

Mechanisms of citric acid-induced bronchoconstriction

In asthma patients, microaspiration of acid into the lower airways (ie, airway acidification) causes such respiratory responses as cough and bronchoconstriction. The mechanism of bronchoconstriction induced by airway acidification is unknown, although evidence is emerging that increasing proton concentrations in airway tissues can activate a subpopulation of primary sensory neurons, so-called capsaicin-sensitive primary sensory neurons, that contain such neuropeptides as the tachykinins substance P (SP) and neurokinin A (NKA). Protons activate a capsaicin-operated channel/receptor, located in the afferents of capsaicin-sensitive neurons, with the subsequent opening of ion channels that are permeable to sodium, potassium, and calcium ions. This event initiates a propagated action potential that antidromically depolarizes collateral fibers and triggers neuropeptide release from nerve fiber varicosities. The tachykinins SP and NKA, released from terminals of primary sensory neurons in peripheral tissues, cause all the major signs of inflammation (neurogenic inflammation) by means of activation of NK(1) and NK(2) receptors. Exposure of the airways to acidic solutions stimulates sensory nerve endings of capsaicin-sensitive sensory neurons and causes different airway responses, including bronchoconstriction. Recently, the NK(2), and to a lesser extent the NK(1), receptors have been shown to be involved with citric acid-induced bronchoconstriction in the guinea pig, which is in part mediated by endogenously released bradykinin. Tachykinins and bradykinin, released by airway acidification, could also modulate citric acid-induced bronchoconstriction by their ability to subsequently release the epithelially derived bronchoprotective nitric oxide (NO). Further study with selective tachykinin NK(1) and NK(2) agonists demonstrated that only the septide-insensitive tachykinin NK(1) receptor releases NO. Thus, bronchoconstriction induced by citric acid inhalation in the guinea pig, mainly caused by the tachykinin NK(2) receptor, is counteracted by bronchoprotective NO after activation of bradykinin B(2) and tachykinin NK(1) receptors in airway epithelium. If a similar mechanism is involved in the pathogenesis of bronchial asthma associated with gastroesophageal reflux in the respiratory tract, new therapeutic strategies should be investigated.

Safety of formoterol Turbuhaler at cumulative dose of 90 microg in patients with acute bronchial obstruction

This study compared the safety of formoterol (Oxis Turbuhaler; 90 microg delivered dose; 120 microg metered dose) with terbutaline (Bricanyl Turbuhaler; 10 mg), in patients with acute bronchoconstriction. Forty-eight patients (31 females) with a mean age of 45 yrs, were randomized into two parallel groups (double-blind design). Mean baseline forced expiratory volume in one second (FEV1) was 0.98 L (33% of predicted normal). Study drugs were administered on six occasions during 3 h (formoterol 4.5 microg or terbutaline 0.5 mg x inhalation(-1), 20 inhalations). Patients received intravenous prednisolone after 1.5 h and oxygen during the first 3 h. Pulse rate, serum potassium, 12-lead electrocardiogram (ECG), Holter ECG, arterial blood gases and FEV1 were assessed during 12 h after the first dose. Four patients (one formoterol, three terbutaline) discontinued. The 12-h mean values of serum potassium decreased from 4.02 to 3.89 mmol x L(-1) for formoterol and from 4.22 to 3.76 mmol x L(-1) for terbutaline. Mean 12-h pulse rate was significantly (p<0.01) higher in the terbutaline group (101.7 beats per minute (bpm)) than in the formoterol group (93.5 bpm). No individual patient value was considered clinically important or alarming. FEV1 improved in both groups but with no statistically significant difference between treatments. Oxis Turbuhaler (90 microg) was at least as safe and well tolerated as terbutaline (10 mg) [DOSAGE ERROR CORRECTED] in patients with acute bronchoconstriction.