Bolus contaminant dispersion in oscillating flow in curved tubes

The investigation of longitudinal dispersion of tracer substances in unsteady flows has biomechanical application in the study of heat and mass transport within the bronchial airways during normal, abnormal, and artificial pulmonary ventilation. To model the effects of airway curvature on intrapulmonary gas transport, we have measured local gas dispersion in axially uniform helical tubes of slight pitch during volume-cycled oscillatory flow. Following a small argon bolus injection into the flow field, the time-averaged effective diffusion coefficient (Deff/Dmol) for axial transport of the contaminant was evaluated from the time-dependent local argon concentration measured with a mass spectrometer. The value of (Deff/Dmol) is extracted from the curve of concentration versus time by two techniques yielding identical results. Experiments were conducted in two helical coiled tubes (delta = 0.031, lambda = 0.022 or delta = 0.085, lambda = 0.060) over a range of 2 < alpha < 15, 3 < A < 15, where delta is the ratio of tube radius to radius of curvature, lambda is the ratio of pitch height to radius of curvature, alpha is the Womersley parameter or dimensionless frequency, and A is the stroke amplitude or dimensionless tidal volume. Experimental results show that, when compared to transport in straight tubes, the effective diffusivity markedly increases in the presence of axial curvature. Results also compare favorably to mathematical predictions of bolus dispersion in a curved tube over the ranges of frequency and tidal volume studied.

Effect of neonatal surfactant therapy on lung function at school age in children born very preterm

Our aim was to evaluate long-term effects of exogenous surfactant therapy on pulmonary functional outcome in children born very preterm. We examined 40 children aged 7-12 years who were born before 30 weeks of gestation with an immature surfactant system, and were randomized to one of three treatment groups: human surfactant given at birth (prophylactic), human surfactant given after development of neonatal respiratory distress syndrome (rescue), and placebo (air) treatment. Spirometric parameters of preterm born children were compared with those of 20 children born at term. In addition, spirometric parameters were monitored twice daily for 4 weeks using a home spirometer. All spirometric parameters were significantly lower in the preterm groups than in the controls, except for the forced vital capacity (FVC) in the prophylactically treated group. Bronchial obstruction was found in 53% of the prophylactically treated group, in 36% of the rescue group, in 67% of the placebo group, and in 0% of the control group. Peak expiratory flow (PEF) and FVC values were higher in those children who received surfactant compared with the placebo group (P < 0.05). In 16 children (40%) born preterm, a beta2-agonist induced an increase in PEF > or = 15% at least three times during 2 weeks of home monitoring; eight children (20%) had abnormal diurnal PEF variation. Multiple regression analysis indicated that the independent variables associated with favorable outcomes in spirometric parameters were surfactant therapy (P = 0.012-0.045) and short intubation time after birth (P = 0.0009-0.0044). Bronchial obstruction, responsiveness to a beta2-agonist, and high diurnal PEF variation are common in children born before 30 gestational weeks. Surfactant supplementation reducing the need for mechanical ventilation or supplementary oxygen after birth may decrease the severity of immaturity related bronchial obstruction in childhood.

Residential dampness problems and symptoms and signs of bronchial obstruction in young Norwegian children

To assess the role of dampness problems and house dust mite exposure in the development of bronchial obstruction in early life, a cohort of 3,754 children born in Oslo during 1992 and 1993 was followed for 2 yr. Bronchial obstruction was defined as two or more episodes with symptoms and signs of obstruction or one lasting 1 mo or more. A matched case-control study was carried out in 251 cases of bronchial obstruction (response rate: 98%) and their 251 paired controls. Information on home dampness problem(s), house dust mite exposure, and potential confounders was collected during home visits and by questionnaires. Dampness problems were confirmed in the homes of 27% of the cases and 14% of the controls, while a concentration of Dermatophagoides pteronyssinus allergens > 2 microg/g dust was found in the beds of 11 (4.5%) cases and three (1.2%) controls. In conditional logistic regression analysis controlling for potential confounders, confirmed dampness problems increased the risk of bronchial obstruction (adjusted odds ratio: 3.8; 95% confidence interval: 2.0-7.2). Exposure to D. pteronyssinus allergens > 2 microg/g dust increased the risk of bronchial obstruction (adjusted odds ratio: 2.8; 95% confidence interval: 0.7-11.7). Residential dampness problems in Oslo dwellings seem to increase symptoms and signs of bronchial obstruction in young children, apparently without increasing their exposure to house dust mites.

Evaluation of respiratory inductive plethysmography in controlled ventilation: measurement of tidal volume and PEEP-induced changes of end-expiratory lung volume

STUDY OBJECTIVE

To determine the accuracy of respiratory inductive plethysmography (RIP) with a respiratory monitor (Respitrace Plus; NIMS Inc., Miami) operating in the DC-mode for the measurement of tidal volumes (VT) and positive end-expiratory pressure (PEEP)-induced changes of end-expiratory lung volume (deltaEELV) in patients with normal pulmonary function, acute lung injury (ALI), and COPD during volume-controlled ventilation.

DESIGN

Prospective comparison of RIP with pneumotachography (PT) for assessment of VT and with multibreath nitrogen washout procedure (N2WO) for determination of deltaEELV as reference methods.

SETTING

Mixed ICU at a university hospital.

PATIENTS

Thirty-one sedated and paralyzed patients: 12 patients with normal pulmonary function mechanically ventilated after major surgery, 10 patients with respiratory failure due to ALI, and 9 patients with a known history of COPD ventilated after surgery or because of respiratory failure due to bronchopulmonary infection.

INTERVENTIONS

Stepwise increase of PEEP from 0 to 5 to 10 cm H2O and reduction to 0 cm H2O again. On each PEEP level, N2WO was performed.

MEASUREMENTS AND MAIN RESULTS

The baseline drift of RIP averaged 25.4+/-29.1 mL/min but changed over a wide range even in single patient measurements. Determination of VT for single minutes revealed that 66.5% and 90.0% of all values were accurate within a range of +/-10% and +/-20%, respectively. The deviation for VT measurements between RIP and PT in patients with COPD was significantly (p<0.05) higher compared to patients with ALI or normal pulmonary function. The difference of deltaEELV between RIP and N2WO was 11.6+/-174.1 mL with correlation coefficients of 0.77 (postoperative and COPD patients) and 0.86 (ALI patients). However, just 25.8% and 46.2% were precise within +/-10% and +/-20%, respectively. deltaEELV determination in COPD patients differed more between RIP and N2WO than in the other groups, but this was not significant.

CONCLUSION

In a mixed group of patients undergoing controlled ventilation, RIP using the Respitrace Plus monitor was not consistently precise enough for quantitative evaluation of VT and EELV when compared to our reference methods. This was most evident in patients with COPD. For long-term volume measurements, a better control of the baseline drift of RIP should be achieved.

Cardiorespiratory response to exercise in patients with exercise-induced bronchial obstruction

OBJECTIVE

To document the characteristics of the ventilatory response to exercise in patients with exercise-induced bronchial obstruction (EIB).

EXPERIMENTAL DESIGN

Comparative study during the period between December 1993 and March 1994.

SETTING

Ambulatory care in Ohgaki Municipal Hospital.

SUBJECTS AND METHOD

We evaluated 11 children with EIB. Each subject under went symptom-limited cardiopulmonary treadmill exercise testing (Bruce protocol).

RESULTS

Patients with EIB showed a significantly lower peak oxygen consumption (peak VO2) than the control subjects. Three patients with EIB developed relative hypoventilation during incremental exercise: an increase in end-tidal carbon dioxide partial pressure (PETCO2) and a decrease in VE/VCO2 were observed at the end-stage of exercise testing.

CONCLUSIONS

These findings demonstrate that some patients with EIB develop bronchoconstriction during exercise.

[Nitric oxide and bronchopulmonary reactivity]

After a brief review concerning NO biosynthesis, distribution and actions, its main normal and pathological implications are presented. The NO modulatory role on the bronchiolar and vascular smooth muscle basal tone, as well as its involvement in local inflammatory reactions are shown. Physiopathological broncho-pulmonary NO implications are completed with data concerning its inhalatory use in the treatment of pulmonary arterial hypertension, acute respiratory distress syndrome and severe pneumonia.

Implantation of Accuflex and Strecker stents in malignant bronchial stenoses by flexible bronchoscopy

Silicone and metal stents are available for the treatment of malignant bronchial stenoses. This project sought to compare the self-expanding nitinol Accuflex stent (Boston Scientific Corp; Watertown, Mass) with the passively expandable tantalum Strecker stent (Boston Scientific Corp; Watertown, Mass), both implanted by flexible bronchoscopy under local anesthesia and sedation. In 51 patients with malignant bronchial stenosis, 14 nitinol and 51 tantalum stents were used and stenoses of 75 to 100% were treated. The intervention was successful in all but one patient; a mean patency of 93% was achieved. In the follow-up period, the probability of survival was significantly lower in patients with total bronchus occlusion than in patients with stenotic alterations (44 vs 109 days; p<0.05). In 10 patients, lung function analysis after stent implantation revealed a significant increase in PaO2 (65 vs 71 mm Hg; p<0.01), inspiratory vital capacity (2.5 vs 2.7 L; p<0.05), and FEV1 (1.8 vs 2.0 L; p<0.05). Mucus retention was the main (39%) adverse factor in the early phase after stent implantation, whereas tumor penetration became the most frequent problem (67%) in the later phase. Recanalizing interventions were necessary in 18% of the cases in which tumor penetration occurred. Stent distortion occurred in 12 patients with Strecker and in none with Accuflex stents. In comparison to the Strecker stent, the self-expanding Accuflex stent is preferable owing to its excellent flexibility and faster delivery system. Both types of stents could be sufficiently deployed within the lesion and allowed for highly precise positioning. Furthermore, no general anesthesia was required. The fiberbronchoscopic mode of implantation under sedation is very efficient even for tumor patients with severe impairment of their physical and respiratory condition.

Bronchial vascular congestion and angiogenesis

The bronchial vasculature is the systemic arterial blood supply to the lung. Although small relative to the pulmonary blood flow, the bronchial vasculature serves important functions and is modified in a variety of pulmonary and airway diseases. Congestion of the bronchial vasculature may narrow the airway lumen in inflammatory airway diseases, and formation of new bronchial vessels (angiogenesis) is implicated in the pathology of a variety of chronic inflammatory, infectious and ischaemic pulmonary diseases. The remarkable ability of the bronchial vasculature to remodel has implications for disease pathogenesis. The contributions of the bronchial vasculature to the pathogenesis of pulmonary disease are reviewed in this article.

[Pulmonary sling or ring-sling complex? respiratory problems--diagnosis, therapy, prognosis]

PS is a rare congenital vascular anomaly in which the left pulmonary artery originates from the right pulmonary artery and courses between trachea and esophagus to the hilus of the left lung causing compression of the right mainstem bronchus and trachea. In about half of all cases this vessel anomaly is associated with tracheo-bronchial and/or cardiovascular malformations. We present 6 patients with PS concentrating on the accompanying malformations of the tracheobronchial tree. All patients had the typical symptoms of wheezing and stridor already in early infancy. 3 patients showed concomitant tracheobronchial anomalies. 2 patients had additional cardiovascular deformities. In 3 of the patients the positive clinical course allowed conservative therapy. In the case of 2 further patients the respiratory problems demanded surgery, one of this patients died. A further patient died after palliative surgery of cardiac anomaly.

[Bronchiectasis--current aspects of an old disease]

Bronchiectasis is pathologically defined as an abnormal and permanent dilatation of one or several bronchi. There are localized and generalized types of bronchiectasis. A vicious circle hypothesis, including an initial insult to the lower airways, impaired mucociliary clearance, microbial colonization/infection, bronchial obstruction and a local inflammatory response, has been proposed to explain the damage to the bronchial tree and the adjacent lung parenchyma. The clinical picture is variable and affected individuals might be asymptomatic or suffer from severe respiratory failure. Daily sputum production is the most common, though unspecific symptom of bronchiectasis. Other common symptoms are hemoptysis and recurrent episodes of sputum purulence, fever and pleurisy. Occasionally, major, life-threatening hemoptysis from a ruptured bronchial artery occurs. Infectious complications, e.g. lung abscess, empyema, brain abscess, and secondary amyloidosis are rarely seen today. The chest radiograph reveals changes suggestive of bronchiectasis in the majority of patients with clinically important disease. High resolution computed tomography of the lung has almost completely replaced bronchography for diagnosis, the latter rarely being of value if surgery is contemplated. No etiology is identified in about one- to two-thirds of the patients, although there are many diseases eventually associated with bronchiectasis. Prevention and therapy of underlying diseases are most important. Traditionally, the therapy of symptomatic bronchiectasis is based on antibiotics, antibronchoobstructive medication, and chest physical therapy. Surgical resection is the treatment of choice for localized symptomatic disease. Bilateral lung transplantation should be considered in younger patients with severe, generalized bronchiectasis and respiratory failure. Prospective, randomized, largescale trials supporting any of the different treatment strategies are not available, but antibiotics and surgery probably have improved the long-term outcome of many patients with bronchiectasis. In this review, some recent findings regarding the classification, pathogenesis, pathology, etiology, diagnosis, treatment, and prognosis of bronchiectasis are discussed.

[Bronchial tuberculosis in the elderly: apropos of 9 cases. Radioclinical, endoscopic and developmental aspects]

We report nine cases of elderly French patients (more than 65 years old) with bronchial tuberculosis. We report the clinical features, radiological and endoscopic aspects. The symptoms are non specific and may delay the diagnostic. The chest X-ray and endoscopic aspects are tumor like. Retractile bronchial stenosis is a potential evolution.

Veterinary practice and occupational health. An epidemiological study of several professional groups of Dutch veterinarians. I. General physical examination and prevalence of allergy, lung function disorders, and bronchial hyperreactivity

The prevalence of allergy, lung function disorders, and bronchial hyperreactivity was studied in 102 Dutch veterinarians, subdivided into five professional groups (predominantly working with either swine, cattle, poultry, companion animals, or as a non-practitioner). The mean age of the participants was 43 years; 6 participants were females. Twenty-two per cent of the participants were overweight, and relatively more non-practitioners than practitioners were overweight. Approximately 23% of the vets reported complaints of prolonged fatigue. The data suggest a relationship between complaints of prolonged fatigue and a more than average number of daily working hours. Only a small proportion of vets were sensitized against several allergens. There were no significant differences in prevalence of distinct lung function disorders or bronchial hyperreactivity between professional groups. It is hypothesized that the respiratory complaints (chronic coughing, chronic phlegm production, stuffed nose, sneezing) reported by the vets predominantly working in swine and/or poultry practice could be caused by irritation and/or inflammation of the first part of the trachea-bronchial tree that has no measurable and permanent consequences for changes in lung function or increased bronchial hyperreactivity. The results of a skin test against allergens and determination of allergen-specific IgE in blood indicated that the respiratory complaints were probably not related to allergy against the panel of allergens tested.

Cigarette smoke-induced bronchoconstriction: causative agents and role of thromboxane receptors

Inhalation of cigarette smoke induces a biphasic bronchoconstriction in guinea pigs: the first phase is induced by a combination of cholinergic reflex and tachykinins, whereas the second phase involves cyclooxygenase metabolites (J.-L. Hong, I. W. Rodger, and L.-Y. Lee. J. Appl. Physiol. 78: 2260-2266, 1995). This study was carried out to further determine the causative agents in the smoke and the types of prostanoid receptors and endogenous prostanoids mediating the bronchoconstriction. Inhalation of 10 ml of high-nicotine cigarette smoke consistently elicited the biphasic bronchoconstriction in anesthetized and artificially ventilated guinea pigs. Pretreatment with hexamethonium (10 mg/kg iv) significantly reduced the first-phase bronchoconstriction but did not have any measurable effect on the second-phase response. In sharp contrast, gas-phase smoke did not elicit any bronchoconstrictive effect. Furthermore, when the animals were challenged with low-nicotine cigarette smoke, only a single second-phase response was evoked, accompanied by increases in thromboxane (Tx) B2 (a stable metabolite of TxA2), prostaglandin (PG) D2, PGF2 alpha in the bronchoalveolar lavage fluid. The bronchoconstrictive response induced by low-nicotine smoke was completely prevented by pretreatment with SQ-29548 (0.3 mg/kg iv), a TxA2-receptor antagonist. These results indicate that 1) nicotine is the primary causative agent responsible for the first-phase bronchoconstriction and 2) nonnicotine smoke particulates evoke the release of TxA2, PGD2, and PGF2 alpha, which act on TxA2 receptors on airway smooth muscles and induce the second-phase response to cigarette smoke.

Effect of the 21-aminosteroid U-74006F on antigen-induced bronchoconstriction and bronchoalveolar eosinophilia in allergic sheep

U-74006F, a non-glucocorticoid 21-aminosteroid, has been developed as an inhibitor of iron-dependent lipid peroxidation. This class of compounds has been shown to prevent antigen-induced eosinophil accumulation in the lungs. In this study, Ascaris-sensitive, "dual-respondent" sheep (showing both immediate (IAR) and late (LAR) asthmatic response) (n = 6) were used to assess the effect of U-74006F on antigen-induced bronchoconstriction and airway inflammation and reactivity 8 h after antigen challenge. Antigen provocation induced dual-phase bronchoconstriction, bronchoalveolar eosinophilia and airway hyperreactivity (AHR) to methacholine. Throughout the experiment, intravenous administration of the drug significantly reduced the IAR and inhibited the LAR along with the inhibition of eosinophil influx, but did not inhibit the increase in airway reactivity observed 8 h after antigen challenge. Post-antigen challenge treatment with U-74006 from 3 h after antigen challenge also significantly reduced the LAR and bronchoalveolar eosinophilia, although the degree of inhibitory effect was milder. The development of the LAR appeared to be dependent on eosinophil recruitment into the lungs. These findings suggest that lipid peroxidation is involved in antigen-induced bronchoconstriction and eosinophil recruitment into the lungs, and that the inhibitor U-74006F may be an effective drug for the treatment of bronchoconstriction and airway inflammation characterized by eosinophil infiltration in asthmatics.

Pulmonary involvement in primary Sjögren's syndrome

Interstitial pulmonary fibrosis and tracheobronchial sicca are the most common presentation of pulmonary involvement in primary Sjögren's syndrome. There is wide spectrum of less common manifestations, including pulmonary arterial hypertension, pseudolymphoma, pulmonary lymphoma, lymphocytic interstitial pneumonitis, amyloidosis, and pleurisy. Pulmonary function test abnormalities showing a restrictive pattern and cellular abnormalities in bronchoalveolar lavage fluid for prevalent in patients without respiratory complaints and normal chest radiographs. Long-term prospective controlled studies are needed to determine the clinical course and significance of these findings.

Foolers: things that look like pneumonia in children

Pulmonary infiltrates on chest radiographs are common findings in the pediatric age group and are generally associated with acute infectious pneumonias. Occasionally, however, these "pneumonias" fail to respond to appropriate antibiotic therapy. Under these circumstances, noninfectious conditions that may be associated with pulmonary infiltrates should be considered. Thus, it is important that physicians who care for children have some knowledge of these potential "mimickers" of childhood pneumonia.

Role of neutral endopeptidase in exercise-induced bronchoconstriction in asthmatic subjects

The membrane-bound metalloproteinase, neutral endopeptidase (NEP), is a degrading enzyme of both bronchoconstrictor and bronchodilator peptides within the airways. To examine the role of NEP in exercise-induced bronchoconstriction (EIB) in asthmatic subjects, we used inhaled thiorphan, a NEP inhibitor, as pretreatment to a 6-min standardized exercise challenge. Thirteen clinically stable asthmatic subjects participated in this double-blind, placebo-controlled, crossover study that was performed on 2 days separated by 48 h. Thiorphan was administered by two inhalations of 0.5 ml containing 1.25 mg/ml. Subsequently, exercise was performed on a bicycle ergometer at 40-50% of predicted maximal voluntary ventilation while inhaling dry air (20 degrees C, relative humidity 6%). The airway response to exercise was measured by forced expiratory volume in 1 s (FEV1) every 3 min, up to 30 min postexercise challenge, and was expressed both as the maximal percent fall in FEV1 from baseline and as the area under the time-response curve (AUC) (0-30 min). The acute effects of both pretreatments on baseline FEV1 were not different (P > 0.2), neither was there any difference in maximal percent fall in FEV1 between thiorphan and placebo (P > 0.7). However, compared with placebo, thiorphan reduced the AUC by, on average, 26% [AUC (0-30 min, +/-SE): 213.6 +/- 47.7 (thiorphan) and 288.6 +/- 46.0%fall.h (placebo); P = 0.047]. These data indicate that NEP inhibition by thiorphan reduces EIB during the recovery period. This suggests that bronchodilator NEP substrates, such as vasoactive intestinal polypeptide or atrial natriuretic peptide, modulate EIB in patients with asthma.

Early and late phase bronchoconstrictions in conscious sensitized guinea-pigs after macro- and microshock inhalation of allergen and associated airway accumulation of leukocytes

Guinea-pigs were sensitized by i.p. injection of 10 micrograms OA and 100 mg aluminium hydroxide in 1 ml normal saline. Fourteen to twenty-one days after sensitization, animals were exposed to macroshock (1% OA for 2 min) or microshock (0.01% for 60 min) inhalation challenges with OA. Animals were protected against fatal anaphylaxis in the case of macroshocks with mepyramine (30mg/kg i.p.) 30 min before exposure. Specific airway conductance (sGaw) was measured in conscious animals by whole body plethysmography at intervals up to 72 h after challenge. An early phase bronchoconstriction peaked significantly (P < 0.05) at 15 min after both macroshock and microshock OA exposures, with maximum falls in sGaw of 70.8 +/- 3.8 and -40.0 +/- 5.9%, respectively. These had resolved after 5 h. A late phase bronchoconstriction peaked variably between 17 and 24 h: the mean peak falls in sGaw after the macro- and microshock challenges were significantly different from baseline (P < 0.05), at -21.6 +/- 3.7 and -38.0 +/- 3.9%, respectively. Control exposures of OA-sensitized guinea-pigs to saline for either 2 or 60 min, in place of OA, produced no significant variation in sGaw values over the predicted early and late phases. Bronchoalveolar lavage (BAL) performed at 5 or 24 h after OA challenge revealed significant increases in total cell numbers (P < 0.05) at 5 and 24 h after the OA macroshock challenge and at 24 h after the microshock, compared with saline challenges. Differential cell counts showed a significant (P < 0.05) increase in the proportion of neutrophils at 5 h and of neutrophils and eosinophils at 24 h after the macroshock exposure to OA, compared with saline controls. A significant (P < 0.05) increase in the proportion of eosinophils also occurred in BAL fluid at 24 h after microshock OA challenge. Neutrophils, however, did not alter at 24 h, yet a late phase bronchoconstriction was recorded. Thus, macroshock (with mepyramine cover) and microshock (without mepyramine cover) OA challenges result in both early and late phase bronchoconstrictions. The late phase is associated with influx of eosinophils in both models but neutrophils only appear after the macroshock, indicating that late phase responses may not involve neutrophil infiltration to the airways.

High-resolution computed tomography of airway changes after induced bronchoconstriction and bronchodilation in asthmatic volunteers

RATIONALE AND OBJECTIVES

We examined whether high-resolution computed tomography (HRCT) would detect and quantify induced airway changes in asthmatic volunteers.

METHODS

We performed pulmonary function tests and HRCT on eight asthmatic adults and two nonasthmatic control adults under three conditions: baseline, after methacholine inhalation, and after albuterol inhalation. Changes in pulmonary function, airway internal luminal diameter (AILD), and airway wall thickness (AWT) in the three conditions were compared.

RESULTS

After methacholine inhalation, pulmonary function showed significant airflow obstruction in the asthmatic volunteers compared with two nonasthmatic control volunteers. The median value for AILD decreased by 17% (p = .04). After subsequent inhalation of albuterol, pulmonary function improved to above the baseline levels in the eight asthmatic volunteers. The median value for AILD increased by 18% above the baseline value (p = .001). No changes in pulmonary function or AILD were seen in the two nonasthmatic volunteers. AWT did not change significantly in either the asthmatic or nonasthmatic volunteers after inhalation of methacholine or albuterol.

CONCLUSION

HRCT can quantify changes in the internal luminal diameter of asthmatic airways provoked by methacholine and albuterol inhalation.

Quantitative assessment of intrathoracic airway collapse in infants and children with tracheobronchomalacia

Tracheobronchomalacia (TBM) is increasingly recognized in infants, children, and adults with acquired chronic lung diseases as the use of flexible bronchoscopy has become widely established in spontaneously breathing patients. However, the lack of a reliable method to quantify the severity of the airway collapse has made serial studies, evaluation of therapies, and comparisons between patients difficult. The purpose of this study was to describe a method of quantifying airway collapse in TBM. The degree of airway collapse was quantitated by measuring the ratio of the smallest to the largest airway area during a respiratory cycle. The videotape of flexible bronchoscopy was run through a video monitor and frozen at the appropriate times. The airway circumference was then traced onto plastic overlays and the area measured. The videotapes of seven infants and children with TBM and eight with normal airways were reviewed by investigators who did not know the diagnosis. Intra-observer variability was 2.2%, and inter-observer variability was 1.4%. The mean smallest/largest airway ratio was 0.34 + or - 0.14 (SD) in the subjects with known TBM, compared with a ratio of 0.82 + or - 0.08 (SD) in children with a normal airway (P< 0.0001). The range in the children with TBM was 0.22-0.61, whereas for the control children it was 0.73-0.93. In this series, there was no overlap in the ratios between affected and unaffected patients. In addition to the manual method of calculating airway area ratios, a computer-assisted method is described that could be adapted to real-time use. This way of analyzing the degree of airway collapse could be used to assess patients with TBM quantitatively and reproducibly.

Bronchiolar disorders with airflow obstruction

Bronchiolar lesions continue to be increasingly recognized as a cause of airflow obstruction. Thus, it is important to have a current update of the current clinical, radiographic, and immunologic perspective of these disorders. Diffuse panbronchiolitis has been reported to occur in the United States and Europe, and the anti-inflammatory action of erythromycin appears to be effective in management. Idiopathic bronchiolitis obliterans, post-fume or post-infectious, or connective tissue disorder bronchiolitis obliterans continues to be rare and often has a poor prognosis. Lung transplantation bronchiolitis obliterans continues to be the major complication and cause of mortality in transplant recipients. Risk factors of this form of chronic rejection include more frequent and more severe acute rejection and the coexistence of organizing pneumonia. The recognition of the distinctive differences among the bronchiolar airflow disorders continues to be essential for improved patient care, greater understanding of the pathogenesis, and development of therapeutic advances.