Small airway function in Finnish COVID-19 survivors

Follow-up studies of COVID-19 patients have found lung function impairment up to six months after initial infection, but small airway function has not previously been studied. Patients (n = 20) hospitalised for a severe SARS-CoV-2 infection underwent spirometry, impulse oscillometry, and multiple measurements of alveolar nitric oxide three to six months after acute infection. None of the patients had small airway obstruction, nor increased nitric oxide concentration in the alveolar level. None of the patients had a reduced FEV₁/FVC or significant bronchodilator responses in IOS or spirometry. In conclusion, we found no evidence of inflammation or dysfunction in the small airways.

Impulse oscillometry and free-running tests for diagnosing asthma and monitoring lung function in young children

BACKGROUND

Separating individuals with viral-induced wheezing from those with asthma is challenging, and there are no guidelines for children under 6 years of age. Impulse oscillometry, however, is feasible in 4-year-old children.

OBJECTIVE

To explore the use of impulse oscillometry in diagnosing and monitoring asthma in young children and evaluating treatment response to inhaled corticosteroid (ICS).

METHODS

A total of 42 children (median age 5.3 years, range 4.0-7.9 years) with physician-diagnosed asthma and lability in oscillometry were followed for 6 months after initiation of ICS treatment. All children performed the 6-minute free-running test and impulse oscillometry at 3 time points. After the baseline, they attended a second visit when they had achieved good asthma control and a third visit approximately 60 days after the second visit. A positive ICS response was defined as having greater than 19 points in asthma control test and no hyperreactivity on the third visit.

RESULTS

In total, 38 of 42 children responded to ICS treatment. Exercise-induced increases of resistance at 5 Hz decreased after ICS treatment (61% vs 18% vs 13.5%, P < .001), and running distance during the 6-minute test was lengthened (800 m vs 850 m vs 850 m, P = .001). Significant improvements in childhood asthma control scores occurred between the baseline and subsequent visits (21 vs 24 vs 24, P < .001) and acute physicians' visits for respiratory symptoms (1, (0-6) vs 0, (0-2), P = .001). Similar profiles were observed in children without aeroallergen sensitization and among those under 5 years of age.

CONCLUSION

Impulse oscillometry is a useful tool in diagnosing asthma and monitoring lung function in young children.

Predictive value of childhood airway hyper-responsiveness to indirect stimuli: 10-year longitudinal study

BACKGROUND

Airway hyper-responsiveness (AHR) is a common feature in asthma. The use of AHR in predicting active asthma or the persistence of AHR in childhood is poorly understood. By analyzing longitudinal connections including different measures of AHR, lung function, and inflammation markers, we sought to identify the best available method for predicting persistence of AHR and identification of later active asthma.

METHODS

We tested 105 asthmatic children aged 3-7 years with fractional exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and AHR evaluated by indirect methods (hypertonic saline and exercise challenge). Ten years later, 64 children participated in the follow-up visit and were tested with FeNO, IOS, spirometry, and methacholine challenge. At both study visits, blood samples were collected, and a questionnaire was completed.

RESULTS

Asthma was in remission in 66% of patients at adolescence. AHR measured by hypertonic saline challenge at preschool age was associated with asthma symptoms (OR 10.2; 95% CI 2.8, 37.3) but not with AHR estimated with methacholine challenge 10 years later. AHR measured by exercise challenge was not associated with AHR or recent asthma symptoms in adolescence. Preschool eosinophilia continued until adolescence in 87% of patients but was not associated with AHR or subjective signs of asthma 10 years later. Wheezy preschoolers with atopy had a higher risk for AHR in adolescence (OR 4.1; 95% CI 1.0, 16.2).

CONCLUSION

Results from hypertonic saline challenge are associated with persistent asthma symptoms even after a decade. AHR measured by indirect methods at preschool age did not predict AHR in adolescence.

Patient Inspiratory Maneuver Performance; Peak Lungpower, Acceleration and Volume

Background: Use of drug delivery devices between nebulizers, dry powder inhalers (DPIs), or metered dose inhalers (MDIs), for treating patients with asthma and chronic obstructive pulmonary disease (COPD), is based on patients' capability of coordinating the inhalation maneuver and achieving sufficient airflow. There are limited data available with regard to how patients meet the requirements of successful inhalation performance, and how the concept of inspiratory lungpower could be applied. The aim of this work was to study the patient inspiratory airflow profile performance in large data sets. We analyzed how the Kamin-Haidl inhalation criteria were met by patients with DPIs such as Easyhaler for combination therapy (EH-combi), Easyhaler for monotherapy (EH-mono), Diskus, and Turbuhaler (TH), and applied peak lungpower instead of peak inspiratory flow rate as an indicator of patient performance. Materials and Methods: Data sets gathered in two previous studies for DPIs, that is, EH-combi, EH-mono, Diskus, and TH, were used to analyze how inspiratory lungpower representing inspiratory muscle power, flow acceleration, and volume after peak met the inhalation criteria. The measured patient airflow profiles through inhalers were assessed for patients with asthma or COPD. Results: Based on the Kamin-Haidl inhalation criteria, successful inhalation requirements were met with EH-combi in 96.1% and with EH-mono in 92.6% of patients. The success rates were 89.5% and 84.6% with Diskus and TH, respectively, (p < 0.0001 between devices). In patients with asthma or COPD, the mean lungpower was 7.51 and 6.15 W for EH-combi, 8.79 and 6.88 W for EH-mono, 7.18 and 4.36 W for Diskus, and 9.65 and 6.86 W for TH, respectively, when patients followed the manufacturer's written instructions. Conclusions: Lungpower applied to the Kamin-Haidl inhalation criteria concept could be an applicable method for reviewing patient performance for different DPIs despite DPIs' characteristic differences in airflow resistance. In light of these results, DPIs provide a feasible treatment option for a large majority of respiratory patients.

Airway hyperresponsiveness, remodeling and inflammation in infants with wheeze

BACKGROUND

The relationship of airway hyperresponsiveness to airway remodeling and inflammation in infants with wheeze is unclear.

OBJECTIVE

To investigate airway hyperresponsiveness, remodeling and inflammation in infants with wheeze and troublesome breathing.

METHODS

Inclusion criteria were as follows: full-term, 3-23 months of age; doctor -diagnosed wheeze and persistent recurrent troublesome breathing; without obvious structural defect, suspicion of ciliary dyskinesia, cystic fibrosis, immune deficiency or specified use of corticosteroids. Airway hyperresponsiveness (AHR) was evaluated by performing a methacholine bronchial challenge test combined with whole body plethysmography and rapid thoracoabdominal compression. Endobronchial biopsies were analysed for remodeling (thickness of reticular basement membrane and amount of airway smooth muscle) and for inflammation (numbers of inflammatory cells). Correlation analyses were performed.

RESULTS

Forty-nine infants fulfilled the inclusion criteria for the present study. Median age was 1.06 years (IQR 0.6; 1.5). Lung function was impaired in 39/49 (80%) children, at the median age of 1.1 years. Methacholine challenge was successfully performed in 38/49 children. Impaired baseline lung function was correlated with AHR (P = .047, Spearman). In children with the most sensitive quartile of AHR, the percentage of median bronchial airway smooth muscle % and the number of bronchial mast cells in airway smooth muscle were not significantly higher compared to others (P = .057 and 0.056, respectively). No association was found between AHR and thickness of reticular basement membrane or inflammatory cells. Only a small group of children with both atopy and AHR (the most reactive quartile) had thicker airway smooth muscle area than non-atopics with AHR (P = .031).

CONCLUSIONS AND CLINICAL RELEVANCE

These findings do not support the concept that AHR in very young children with wheeze is determined by eosinophilic inflammation or clear-cut remodeling although it is associated with impaired baseline lung function. The possible association of increased airway smooth muscle area among atopic children with AHR remains to be confirmed.

Serum chitinase-like protein YKL-40 is linked to small airway function in children with asthmatic symptoms

BACKGROUND

Lung function impairment among asthmatic children begins in early life, and biomarkers for identifying this impairment are needed. The chitinase-like protein YKL-40 has been associated with asthma and lung function in adults, but studies in children have yielded conflicting results. We evaluated the potential of YKL-40 and other systemic biomarkers for identifying lung function deficits in children with asthmatic symptoms.

METHODS

We determined the levels of serum YKL-40, periostin, and high-sensitivity C-reactive protein (hs-CRP) from the blood samples of 49 children with asthmatic symptoms. Lung function was assessed with impulse oscillometry (IOS) and spirometry, combined with an exercise challenge and a bronchodilator test. Fractional exhaled nitric oxide was measured at multiple flow rates.

RESULTS

Serum levels of YKL-40 showed significant correlations with most IOS indices at baseline (P = .008-.039), but there was no association between YKL-40 and spirometry parameters. Neither periostin nor hs-CRP were associated with baseline lung function. Children with a significant response in either the exercise challenge or the bronchodilator test had increased serum levels of YKL-40 (P = .003) and periostin (P = .035). YKL-40 correlated significantly with the blood neutrophil count (r_s  = .397, P = .005) but was not associated with biomarkers of eosinophilic inflammation.

CONCLUSION

Serum YKL-40 is a potential biomarker for lung function deficits in children with asthmatic symptoms. These deficits appear to be focused on small airways and may remain undetected with spirometry.

Converting FENO by different flows to standard flow FENO

In clinical practice, assessment of expiratory nitric oxide (FENO ) may reveal eosinophilic airway inflammation in asthmatic and other pulmonary diseases. Currently, measuring of FENO is standardized to exhaled flow level of 50 ml s-1 , since the expiratory flow rate affects the FENO results. To enable the comparison of FENO measured with different expiratory flows, we firstly aimed to establish a conversion model to estimate FENO at the standard flow level, and secondly, validate it in five external populations. FENO measurements were obtained from 30 volunteers (mixed adult population) at the following multiple expiratory flow rates: 50, 30, 100 and 300 ml s-1 , after different mouthwash settings, and a conversion model was developed. We tested the conversion model in five populations: healthy adults, healthy children, and patients with COPD, asthma and alveolitis. FENO conversions in the mixed adult population, in healthy adults and in children, showed the lowest deviation between estimatedF ^ ENO from 100 ml s-1 and measured FENO at 50 mL s-1 : -0·28 ppb, -0·44 ppb and 0·27 ppb, respectively. In patients with COPD, asthma and alveolitis, the deviation was -1·16 ppb, -1·68 ppb and 1·47 ppb, respectively. We proposed a valid model to convert FENO in healthy or mixed populations, as well as in subjects with obstructive pulmonary diseases and found it suitable for converting FENO measured with different expiratory flows to the standard flow in large epidemiological data, but not on individual level. In conclusion, a model to convert FENO from different flows to the standard flow was established and validated.

Inspiratory and Expiratory Flow Changes, Voice Symptoms and Laryngeal Findings during Histamine Challenge Tests

OBJECTIVE

The aim of this study was to analyse the associations between the spirometry parameter changes in relation to laryngeal finding changes and self-reported voice and throat symptom changes among patients undergoing a histamine challenge test.

PATIENTS AND METHODS

Thirty adult patients with a chronic cough underwent a histamine challenge test. Videolaryngostroboscopy and voice and throat symptoms were assessed using a visual analogue scale immediately before and after the challenge test. Correlations between the relative changes in spirometry values in relation to the change in vocal fold oedema and redness and self-reported voice and throat symptom changes during the challenge test were assessed.

RESULTS

A correlation between the relative change in inspiratory and expiratory air flow values and the change in voice and throat symptoms during the histamine challenge test was found. The vocal fold oedema, visible on videolaryngostroboscopy, caused by the histamine challenge did not significantly affect the spirometry air flow values.

CONCLUSION

The relative changes in inspiratory and expiratory air flow and voice and throat symptoms during the histamine challenge test correlated. The vocal fold oedema caused by the histamine challenge, visible on videolaryngostroboscopy, did not significantly affect the spirometry air flow values.

Standardizing dose in dosimetric bronchial challenge tests

Recent technical recommendations on bronchial challenge testing aim at standardized assessment of provocative dose of causing 20% decrease in FEV1 (PD20). The aim of this study was to investigate the effect of mode of nebulization on the output of a computerized dosimeter (APS) and to compare PD20 obtained by two different dosimetric systems in vivo. The output of the APS system was tested during continuous nebulization, and using simulated breaths, for intermittent actuations with four different durations. Using output data, a modified methacholine challenge protocol was applied for APS and compared with a standard set-up using Spira dosimeter in 14 asthmatic patients attending duplicate methacholine challenges using both systems, within median (range) 3 (1-6) days apart. The calculated output (mg min^-1 ) with all the intermittent mode settings was significantly higher (P<0·001) than in the continuous mode, and in the intermittent mode, the output was dependent of the pulse duration. The PD20 values assessed with the APS and Spira systems were significantly correlated (r = 0·69; P<0·007), without systematic difference in the geometric means (P = 0·10). A moderate to good agreement was found for assessment of significant hyperresponsiveness. The results suggest that in dosimetric systems for bronchial challenge tests, the output of the nebulizer is dependent on the mode of nebulization, and this should be considered when standardizing the dose between devices and protocols. As long as the delivered dose is determined for the specified nebulization mode of the protocol, it may be possible to obtain comparable results between different devices.

Small airway oscillometry indices: Repeatability and bronchodilator responsiveness in young children

INTRODUCTION

The impulse oscillometry (IOS) indices absolute and relative difference between respiratory resistance at 5 and 20 Hz (R5-20 and R5-20%, respectively) and the area under the reactance curve (AX) are postulated to reflect small airway function. Data on their cutoff values to evaluate bronchodilator responsiveness (BDR) or between-visit changes after interventions are limited in young children.

METHODS

We evaluated the BDR of 103 healthy children aged 2-7 years, who received either salbutamol (n = 84) or placebo (n = 19) in order to determine cutoff values for BDR of R5-20, R5-20%, and AX. We then determined the repeatability within and between two IOS measurements 7-14 days apart in young children aged 4-8 years with asthmatic symptoms (n = 43), including cutoff values for significant between-visit changes.

RESULTS

The investigated IOS parameters showed marked BDR (fifth percentile cutoff of 75-110% of the baseline value) in healthy children, whereas no significant changes were seen after inhalation of placebo. The agreement within the triplicate IOS measurement was excellent (ICC > 0.80), and the agreement of results between visits was good (ICC > 0.60). A change in R5-20, R5-20%, and AX of 0.65, 1.08, and 0.84 z-scores, respectively, would exceed 95% confidence intervals for between-visit variability.

CONCLUSION

We introduce cutoff values for BDR of R5-20, R5-20%, and AX, and their repeatability indices and cutoff limits for significant between-visit changes. These IOS parameters may show greater variability than the conventional IOS indices during follow-up, but the between-visit agreement remains good, providing potentially useful endpoints for monitoring lung function in young children.

Double-blind placebo-controlled challenge showed that peanut oral immunotherapy was effective for severe allergy without negative effects on airway inflammation

AIM

This study examined the efficacy and the safety of peanut oral immunotherapy (OIT).

METHODS

We recruited 60 patients aged six years to 18 years who had a moderate-to-severe reaction to a double-blind placebo-controlled peanut challenge: 39 received OIT during an eight-month build-up phase and maintenance phase and 21 controls avoided peanuts. We measured specific immunoglobulin E and G4 (IgE and IgG4) to peanuts and to Ara h 1, 2, 3, 8 and 9 and monitored adverse events, bronchial hyper-responsiveness (BHR) to methacholine and fractional concentrations of exhaled nitric oxide (FeNO). The median follow-up period was 30 months.

RESULTS

Most (85%) of the OIT patients passed the build-up phase and 67% tolerated 5 g of peanuts during the post-treatment challenge. No controls were desensitised, with a risk ratio of 29 and 95% confidence interval of 1.9-455. During OIT, IgE to peanut, Ara h 1, 2 and 3 decreased and IgG4 increased. Consuming peanuts had no harmful effects on BHR or FeNO. The annual incidence rate of emergency visits during the follow-up period was 11% or 3.0 per 10 000 patient-days.

CONCLUSION

Peanut OIT was efficacious in severe allergies without negative effects on airway inflammation, but unpredictable long-term reactions might occur.

Measurement of tidal breathing flows in infants using impedance pneumography

Tidal breathing flow volume (TBFV) profiles have been used to characterise altered lung function. Impedance pneumography (IP) is a novel option for assessing TBFV curves noninvasively. The aim of this study was to extend the application of IP for infants and to estimate the agreement between IP and direct pneumotachograph (PNT) measurements in assessing tidal airflow and flow-derived indices.

Tidal flow profiles were recorded for 1 min simultaneously with PNT and uncalibrated IP at baseline in 44 symptomatic infants, and after methacholine-induced bronchoconstriction in a subgroup (n=20).

The agreement expressed as the mean deviation from linearity ranged between 3.9 and 4.3% of tidal peak inspiratory flow, but was associated with specific airway conductance (p=0.002) and maximal flow at functional residual capacity (V′maxFRC) (p=0.004) at baseline. Acute bronchoconstriction induced by methacholine did not significantly affect the agreement of IP with PNT. TBFV indices derived from IP were slightly underestimated compared to PNT, but were equally well repeatable and associated with baseline V′maxFRC (p=0.012 and p=0.013, respectively).

TBFV profiles were consistent between IP and PNT in most infants, but the agreement was affected by reduced lung function. TBFV parameters were not interchangeable between IP and PNT, but had a similar association with lung function in infants.

Laryngeal Mucosal Reaction during Bronchial Histamine Challenge Test Visualized by Videolaryngostroboscopy

OBJECTIVES/HYPOTHESIS

To examine the changes in the larynx, as well as self-reported voice and throat symptoms, among patients undergoing a histamine challenge test. Thus, to understand the possible clinical effects of histamine on the larynx.

STUDY DESIGN

Controlled, open prospective study.

METHODS

Thirty adult patients with prolonged cough and suspicion of bronchial asthma underwent a histamine challenge test. Videolaryngostroboscopy was performed immediately before and after the challenge. Voice and throat symptoms immediately before and after the challenge test were assessed using a visual analog scale.

RESULTS

Videolaryngostroboscopy after exposure showed significant increases in edema (P < 0.001) as well as redness (P < 0.001) of the vocal folds after the exposure. Self-reported voice complaints increased significantly for 8 of 11 symptoms. A moderate positive correlation was found between the increase in edema of the vocal folds and reported heartburn/regurgitation symptoms (r = 0.42, P < 0.05). Atopy, asthma, nasal symptoms, or bronchial hyperreactivity during the histamine challenge test were not associated with laryngeal reactions.

CONCLUSIONS

According to the results, the laryngeal mucosal reaction during a histamine challenge test can be objectively visualized. Videolaryngostroboscopy findings, together with an increase in self-reported voice and throat symptoms, show that histamine has potential effects on vocal folds. The mucosal reaction seems to be pronounced among patients with reflux symptoms, probably reflecting the permeability features of the vocal folds.

Exhaled nitric oxide indicates poorly athlete's asthma

INTRODUCTION

In athletes, exercise-induced respiratory symptoms are common and their assessment is time and resource consuming.

OBJECTIVE

The objective was to evaluate fractional concentration of exhaled nitric oxide (FENO) as a predictor of bronchial hyperresponsiveness (BHR) and of asthma.

MATERIALS AND METHODS

Eighty-seven elite athletes and a control group of 87 sedentary patients with symptoms suggesting asthma underwent measurements of FENO and of BHR by using methacholine provocation test (MCH) and eucapnic voluntary hyperpnoea (EVH) (athletes) or histamine provocation test (HIST) (controls).

RESULTS

In athletes, elevated FENO (>30 ppb) was not associated with lung function-confirmed asthma or with MCH positivity, but receiver operating characteristics (ROC) analysis showed some predictive value for EVH positivity [Area Under Curve (AUC) 0.652, 95% confidence interval (CI): 0.53 to 0.78, P = 0.020]. However, the sensitivity (55%) and the specificity (71%) were poor. In sedentary patients, FENO was significantly associated with both confirmed asthma and HIST positivity, ROC analysis showing FENO to be significantly predictive for HIST positivity (AUC 0.83, 95% CI: 0.70 to 0.96, P = 0.001) and for asthma (AUC 0.74, 95% CI: 0.63 to 0.85, P < 0.001).

CONCLUSION

The results suggest that in contrast to sedentary patients, FENO seems to be a poor predictor of BHR and of clinical asthma in elite athletes. We find it unlikely that FENO could be a useful screening tool in athletes with exercise-induced respiratory symptoms.

Cow's milk allergy as a predictor of bronchial hyperresponsiveness and airway inflammation at school age

BACKGROUND

Cow's milk allergy (CMA) has been found to be associated with an increased incidence of asthma at school age. However, prospective population-based studies of CMA and the development of airway inflammation and bronchial hyperresponsivess (BHR) are lacking.

OBJECTIVE

The aims of this study was to evaluate CMA as a risk factor for BHR and airway inflammation presented later in childhood.

METHODS

We followed prospectively 118 children with CMA and invited them to a clinical visit at a mean age of 8.6 years including the measurement of exhaled nitric oxide (FE(NO) ) and bronchial challenge with histamine. Ninety-four patients and 80 control subjects from the same cohort participated.

RESULTS

At school age, children with a history of CMA had higher FE(NO) levels (P=0.0009) and more pronounced responsiveness to histamine (P=0.027) than their controls. Stratified analysis showed a significant difference only in IgE-positive CMA. Multinomial logistic regression analysis showed that IgE-positive CMA [odds ratio (OR) 3.51; 95% confidence intervals (CI) 1.56-7.90; P=0.002] and a history of wheeze during the first year of life (OR 2.81; 95% CI 1.16-6.84; P=0.023) were independent explanatory factors for increased FE(NO) , and IgE-positive CMA (OR 3.37; 95% CI 1.03-10.97; P=0.044) and parental smoking (OR 3.41; 95% CI 1.14-10.22; P=0.028) for increased BHR, whereas for IgE-negative CMA, no associations with FE(NO) or BHR were found. In the CMA group, those exposed to CM very early at the maternity hospital, had less BHR (P=0.002).

CONCLUSIONS

Compared with their controls, children with a history of IgE-positive CMA show signs of airway inflammation, expressed as higher FE(NO) , and more pronounced bronchial responsiveness to histamine at school age. In contrast to IgE-negative CMA, IgE-positive CMA is a significant predictor of increased FE(NO) and BHR at school age. Very early exposure to CM was associated with less BHR.

Clinical findings associated with abnormal lung function in children aged 3-26 months with recurrent respiratory symptoms

AIM

To evaluate whether there are any associations between parentally reported symptoms, clinical findings and lung function in young children with recurrent lower respiratory tract symptoms.

METHODS

In 2000-2003, 148 children, aged 3-26 months, with recurrent lower respiratory tract symptoms underwent physical examination, investigation of a chest radiograph, whole body plethysmography and skin prick testing to common food and inhalant allergens.

RESULTS

Lung function was considered abnormal (i.e. functional residual capacity z-score of > or =1.65 and/or specific conductance z-score of < or =-1.65) in 83 (56%) children. Findings of increased work of breathing (p < 0.001) and nonspecific noisy breathing sounds (p < 0.001) in the physical examination, as well as an abnormal chest radiograph (p = 0.028) were independently associated with abnormal lung function, explaining up to 34% of the variation in lung function. In contrast, parentally reported respiratory symptoms, environmental exposures or atopic trait were not associated with lung function abnormalities.

CONCLUSION

The results of this study emphasize the importance of the meticulous clinical examination in the evaluation of early childhood respiratory disorders. As physical examination alone cannot predict lung function abnormalities reliably in preschool children with troublesome respiratory symptoms, lung function testing may be considered in such patients to obtain additional objective information.

Budesonide improves decreased airway conductance in infants with respiratory symptoms

OBJECTIVE

Inhaled corticosteroids (ICS) are commonly used to treat wheezing disorders in children, but few studies have investigated the effect of ICS on lung function in infants. We evaluated the efficacy of inhaled budesonide for decreased specific airway conductance (sGaw) as an indication of bronchial obstruction in very young children with recurrent cough and/or wheeze. PATIENTS, DESIGN AND INTERVENTIONS: Functional residual capacity (FRC) and sGaw of steroid-naive children aged 3-26 months with respiratory symptoms were measured using an infant whole-body plethysmograph. Clinically indicated bronchoscopy was performed in 79% of the patients to exclude anatomical abnormalities before randomisation. Children with abnormal lung function and respiratory symptoms were randomised into two treatment groups, receiving either inhaled budesonide (400 microg/day) or placebo with NebuChamber for 6 weeks. Inhaled terbutaline 0.25 mg/dose was used as a rescue medication. Lung function measurements were repeated after 6 weeks.

MAIN OUTCOME MEASURE

Lung function.

RESULTS

44 children with a median age of 11.3 months (range 3.7-25.9) completed the study. Median sGaw improved from a z score of -3.6 to -1.2 (p<0.001) in the budesonide group and from -3.2 to -2.6 (p = 0.033) in the placebo group; between group difference p = 0.014. Improvement in sGaw was more pronounced in children with atopy (p = 0.017). Symptom-free days increased in both the budesonide and placebo groups with no difference between groups.

CONCLUSION

Treatment with inhaled budesonide for 6 weeks improved sGaw in young children with chronic cough or wheeze and bronchial obstruction.

Effect of adenoidectomy on respiratory function: a randomised prospective study

OBJECTIVE

Risk of childhood asthma is increased in children with recurrent otitis media. This may be associated with recurrent respiratory tract infections in these children, but the role of adenoidectomy, a frequent operation during childhood, is unknown. Therefore, the role of adenoidectomy in the development of atopy and respiratory function changes characteristic of asthma was evaluated.

DESIGN

Randomised controlled study.

SETTING

Tertiary care centre.

PATIENTS

166 children aged 12-48 months who had recurrent or persistent otitis media and who were followed-up for 3 years after randomisation.

INTERVENTION

Randomisation to undergo insertion of tympanostomy tubes with or without adenoidectomy.

MAIN OUTCOME MEASURES

The primary outcome measure was exercise-induced bronchoconstriction as evaluated by impulse oscillometry. The secondary outcome measures were bronchial inflammation as evaluated by exhaled nitric oxide and atopy as evaluated by skin prick tests. During the 3-year follow-up period otitis media episodes were documented in patient diaries.

RESULTS

Adenoidectomy did not significantly influence baseline lung function, exercise-induced bronchoconstriction, exhaled nitric oxide concentration, the development of positive skin prick tests, or doctor-diagnosed asthma. Adenoidectomy did not significantly prevent otitis media. Recurrent otitis media (>or=4 episodes) during the first follow-up year was associated with an abnormal exercise-induced bronchoconstriction (OR 6.62, 95% CI 1.27 to 34) and an elevated exhaled nitric oxide concentration (OR 3.26, 95% CI 0.98 to 10.8) regardless of adenoidectomy.

CONCLUSIONS

Adenoidectomy did not promote asthma or allergy. Recurrent respiratory tract infections during early childhood are associated with the risk of bronchial hyper-reactivity.

Bronchial response pattern of antigen presenting cells and regulatory T cells in children less than 2 years of age

BACKGROUND

In early childhood, the ability to mount protective immune responses in the airways is impaired, with increased risk of allergic sensitisation to inhaled allergens. Antigen presenting cells (APC) and regulatory T cells (Treg) are important modifiers of T cell immunity but little is known about their distribution in bronchial mucosa at this age. Here the subset distribution of APC and the appearance of Foxp3(+) Treg and bronchus associated lymphoid tissue (BALT) were examined immunohistochemically in children less than 2 years of age with chronic asthma-like symptoms of the lower airways.

METHODS

Immunophenotyping was performed in situ on bronchial biopsy specimens obtained from 45 infants, 4-23 months of age, under investigation for airway disease.

RESULTS

A well developed HLA-DR(+) network of APC was present in all samples, approximately 50% of the cells being CD68(+) macrophages and the remainder various subsets of dendritic cells. The density of HLA-DR(+) cells increased significantly with age but was not related to atopy, clinical symptoms or lung function. Comparing the density of APC subsets and clinical parameters, only the number of intraepithelial CD1a(+) dendritic cells was significantly increased in infants who had recently suffered a respiratory infection. BALT structures were identified in 22 children, with no relation to lung function, atopic status or human rhinovirus positivity. Plasmacytoid dendritic cells and Foxp3(+) Treg were located primarily within these isolated lymphoid follicles.

CONCLUSION

A bronchial network of dendritic cells and macrophages develops quite rapidly after birth, apparently independent of clinical symptoms or atopy. The high frequency of BALT structures containing putative tolerogenic dendritic cells and Treg suggests that these lymphoid follicles play an important role in bronchial immune homeostasis during infancy.

Airway responsiveness: associated features in infants with recurrent respiratory symptoms

Increased airway responsiveness (AR) is one of the main pathophysiological manifestations of asthma. The present study aimed to define the clinical features associated with increased AR in infants with recurrent lower respiratory tract symptoms. AR was evaluated by performing a novel dosimetric methacholine challenge test. Increased AR to methacholine, defined as a methacholine dose of < or =0.90 mg producing a 40% fall (PD(40)) in the maximal flow at functional residual capacity (V'(max,FRC)), was associated with atopy (odds ratio (OR) 4.1; 95% confidence interval (CI) 1.3-13.3), a history of physician-confirmed wheezing with respiratory syncytial virus (OR 32.9; 95% CI 2.5-428.8) or of a nonspecified aetiology (OR 4.9; 95% CI 1.1-22.5), functional residual capacity z-score > or =2 (OR 36.8; 95% CI 2.9-472.6), and V'(max,FRC) z-score (OR 0.5; 95% CI 0.2-0.9) at baseline, when compared with infants with only mild or no responsiveness to methacholine (PD(40) V'(max,FRC) >0.90 mg). In conclusion, in recurrently symptomatic infants, increased airway responsiveness is associated with reduced baseline lung function, an atopic trait of the child, a history of physician-confirmed wheeze and viral aetiology of wheeze. Future intervention studies are needed to confirm the role of airway responsiveness in respiratory morbidity during infancy.

Formoterol as needed with or without budesonide in patients with intermittent asthma and raised NO levels in exhaled air: A SOMA study

Patients with mild intermittent asthma sometimes show signs of inflammation, and guidelines suggesting bronchodilator therapy alone as needed may be questioned. The current study compared as-needed use of a rapid-acting beta2-agonist with as-needed use of a beta2-agonist and corticosteroid combination as the only medication in asthma patients with intermittent symptoms. A total of 92 nonsmoking asthma patients (of 187 screened) using only an inhaled beta2-agonist as needed (28 males, 64 females; mean age 37 yrs; mean forced expiratory volume in one second (FEV1) 101% predicted, mean reversibility 6.5% pred and fractional exhaled nitric oxide (FeNO) > or =20 parts per billion (ppb)) were randomised to treatment with formoterol (Oxis Turbuhaler) 4.5 microg as needed (n = 47) or budesonide/formoterol (Symbicort Turbuhaler) 160/4.5 microg as needed (n = 45) in a double-blind, parallel-group 24-week study. The primary variable of efficacy was change in FeNO. Baseline FeNO was 60 ppb and 59 ppb in the budesonide/formoterol and formoterol groups, respectively. Mean reductions in FeNO in the budesonide/formoterol and formoterol groups were 18.2 ppb and 2.8 ppb, respectively (95% confidence interval (CI) 7.5-23.5 ppb). The reduction in the budesonide/formoterol group occurred during the first 4 weeks of treatment and remained at this low level. Mean FEV1 increased by 1.8% pred normal value in the budesonide/formoterol group and decreased by 0.9% pred normal value in the formoterol group (95% CI -4.7- -0.7). In the budesonide/formoterol group, use of > or =4 inhalations x day(-1) of study medication was seen on 21 treatment days compared with 74 in the formoterol group. In conclusion, as-needed use of an inhaled corticosteroid together with a rapid-acting bronchodilator may be more beneficial than a beta2-agonist alone in patients with intermittent asthma and signs of airway inflammation. The long-term benefits are unknown.

Reference values for respiratory system impedance by using impulse oscillometry in children aged 2-11 years

The forced oscillation technique makes it possible to evaluate the mechanical properties of the respiratory system with a minimum of cooperation. The method is therefore especially useful in children. Impulse oscillometry (IOS) is a commercially available version of this technique. There is, as yet, limited information on reference values for IOS in children. The aim of this study was to extend the reference values for IOS variables and to study their correlation with height, weight and age in healthy children. A sample (n = 360) of children (age 2.1-11.1 years) was measured by using impulse oscillometry (IOS; Jaeger, Würzburg, Germany). The sample was based on children attending kindergarten in Finland and children attending primary school in Sweden. Measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs) and the resonance frequency (Fr) were made. All variables were related to body height. Most of them were also weakly related to weight. Reference equations for children (height 90-160 cm) are presented.

Exhaled nitric oxide in healthy nonatopic school-age children: determinants and height-adjusted reference values

Exhaled nitric oxide (FENO) was proposed as a marker of airway inflammation, but data about FENO in healthy children measured with standardized methods are so far limited. In order to assess the determinants of FENO in healthy children, we investigated a population-based sample of school-age children (n = 276) with a questionnaire, skin-prick tests, spirometry, and the measurement of FENO. The FENO of 114 nonatopic and nonsmoking children considered healthy were analyzed with stepwise multiple regression analysis, which showed significant associations with age, standing height, weight, and body surface area, but not with gender. Height was found to be the best independent variable for the regression equation for FENO, which on average showed an increase in the height range of 120-180 cm from 7 to 14 ppb. In the random sample of children, increased FENO was associated with atopy (odds ratio, 9.0; 95% confidence interval, 3.9-21.1; P < 0.0001), and significantly with allergic rhinitis and atopic dermatitis, but not with asthma. Respiratory symptom-free children with skin-prick test positivity had significantly higher FENO than healthy nonatopic subjects. We conclude that height is the best determinant of FENO in healthy children. Due to the strong effect of atopy, FENO data should not be interpreted without knowing the atopic status of the child. The present reference values of FENO may serve in clinical assessments for measuring airway inflammation in children.

Determinants of increased exhaled nitric oxide in patients with suspected asthma

Exhaled nitric oxide (FENO) has been proposed as a marker of asthmatic inflammation, but it is unclear whether FENO in clinical use selects patients primarily according to their atopic or asthmatic status. The aim of this study was to investigate the determinants of increased FENO in patients with suspected asthma, by means of multinomial logistic regression analysis. The FENO of 132 patients referred because of symptoms suggestive of asthma were studied, and the explanatory factors tested included atopy according to prick skin tests, clinical asthma according to lung function tests, sputum eosinophilia and bronchial hyperresponsiveness (BHR). Slightly elevated FE(NO) levels were significantly explained only by sputum eosinophilia (OR: 3.7; 95% CI: 1.1-13.1; P=0.04), but for high levels of FE(NO) (> or =3 SD of predicted), clinical asthma (OR: 16.3; 95% CI: 5.4-49.7; P <0.0001) and sputum eosinophilia (OR: 12.0; 95% CI: 4.1-35.0; P >0.0001) were the characteristics with the highest prediction, followed by atopy and BHR. A significant interaction between asthma and atopy was observed relating to the effect on high FENO, but further analyses stratified by atopy showed significant associations between asthma and high FENO both in atopic and nonatopic patients. We conclude that in patients with symptoms suggesting asthma, slightly elevated and high levels of FENO are associated with sputum eosinophilia, whereas asthma is significantly associated only with high levels of FENO, irrespective of atopy. The results suggest that FENO is primarily a marker of airway eosinophilia, and that only high values of FENO may be useful to identify patients with atopic or nonatopic asthma.

Controlled trial of dexamethasone in neonatal chronic lung disease: an 8-year follow-up of cardiopulmonary function and growth

AIM

To evaluate the long-term effects of postnatal dexamethasone treatment in high-risk infants of very low birthweight.

METHODS

The study included 16 children aged 7.8 to 9.2 y who had been born very prematurely at gestational ages of 24-29 wk and with birthweights of < 1500 g and who had participated in a randomized study of dexamethasone or placebo treatment in ventilator-dependent infants at 10 d of age. Flow-volume spirometry, impulse oscillometry, skin-prick tests and Doppler echocardiography were carried out at school age, and respiratory morbidity and overall neurological outcome evaluated. Controls were 18 non-atopic children born at term, tested for lung function.

RESULTS

No significant differences were found in respiratory morbidity at school age between the dexamethasone (n = 8) and placebo (n = 8) groups. Six of the 16 children had moderate to severe neurosensory impairments, but all were able to walk without support and attended primary school. In prematurely born children, standardized height was significantly less than that in controls, but between the two study groups, no significant differences existed in somatic growth. Atopy was uncommon: skin-prick tests were positive in only one child in the placebo group. In the dexamethasone group, forced vital capacity adjusted to height was significantly higher than that in the placebo group, but impairment of basic lung function and bronchial obstruction was evident in both study groups. No hypertrophic cardiomyopathy was apparent, and non-invasive measurements of pulmonary arterial pressure did not reveal any significant difference between the study groups.

CONCLUSION

In very low-birthweight children, high respiratory morbidity and neurological impairment continued until school age. Neonatal dexamethasone treatment at school age was not associated with any detectable adverse effects on somatic growth, or pulmonary or cardiac function.

Exhaled nitric oxide rather than lung function distinguishes preschool children with probable asthma

BACKGROUND

Respiratory function and airway inflammation can be evaluated in preschool children with special techniques, but their relative power in identifying young children with asthma has not been studied. This study was undertaken to compare the value of exhaled nitric oxide (FE(NO)), baseline lung function, and bronchodilator responsiveness in identifying children with newly detected probable asthma.

METHODS

Ninety six preschool children (age 3.8-7.5 years) with asthmatic symptoms or history and 62 age matched healthy non-atopic controls were studied. FE(NO) was measured with the standard online single exhalation technique, and baseline lung function and bronchodilator responsiveness were measured using impulse oscillometry (IOS).

RESULTS

Children with probable asthma (n=21), characterised by recent recurrent wheeze, had a significantly higher mean (SE) concentration of FE(NO) than controls (22.1 (3.4) ppb v 5.3 (0.4) ppb; mean difference 16.8 ppb, 95% CI 12.0 to 21.5) and also had higher baseline respiratory resistance, lower reactance, and larger bronchodilator responses expressed as the change in resistance after inhalation of salbutamol. Children with chronic cough only (n=46) also had significantly raised mean FE(NO) (9.2 (1.5) ppb; mean difference 3.9 ppb, 95% CI 0.8 to 7.0) but their lung function was not significantly reduced. Children on inhaled steroids due to previously diagnosed asthma (n=29) differed from the controls only in their baseline lung function. The analysis of receiver operating characteristics (ROC) showed that FE(NO) provided the best power for discriminating between children with probable asthma and healthy controls, with a sensitivity of 86% and specificity of 92% at the cut off level of 1.5 SD above predicted.

CONCLUSIONS

FE(NO) is superior to baseline respiratory function and bronchodilator responsiveness in identifying preschool children with probable asthma. The results emphasise the presence of airway inflammation in the early stages of asthma, even in young children.

Determinants of respiratory system input impedance and bronchodilator response in healthy Finnish preschool children

In order to study the determinants of respiratory system impedance and bronchodilator response in preschool children, a sample (n = 109) of healthy children (age 2.1-7.0 years) attending kindergarten was measured by using the impulse oscillometry. Their selection was based on a standardized questionnaire, negative skin prick test results and clinical examination, and sufficient cooperation. Triple measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs), the resonance frequency (Fr) and the frequency dependence of resistance (dRrs/df) were performed, to determine individual mean values. Measurements were repeated after inhalation of 300 microg salbutamol (n = 89) or placebo (n = 19). At the baseline, Zrs and Rrs5-20 showed negative, and Xrs5-20, Fr and dRrs/df positive correlations with age, height and weight. However, logarithmic transformed height was the best independent variable for the regression equations of all the oscillometric variables. After inhalation of placebo, none of the oscillometric variables changed significantly. In the salbutamol group, the mean (SD) change in Rrs5 was -0.187 (0.124) kPa l(-1) s(-1) and -19.2 (10.2)%, corresponding to a lower reference limit of -36.9%. Both the within-test and between-test repeatabilities for the measurement of respiratory resistance were acceptable, for Rrs5 the coefficients of variation being 6.2 and 6.1%, respectively. As the overall success rate in our sample was high (89%), the forced oscillation technique seems to be a useful method in assessing respiratory function and bronchial lability in preschool children.

Acceptability, reproducibility, and sensitivity of forced expiratory volumes and peak expiratory flow during bronchial challenge testing in asthmatic children

OBJECTIVES

To compare the acceptability, reproducibility, and sensitivity of spirometric outcome measures of airway caliber during challenge testing in children.

DESIGN

FEV(1), forced expiratory volume in 0.75 s, forced expiratory volume in 0.5 s, and peak expiratory flow (PEF) were recorded during stepwise dosimetric histamine challenge tests. The responses were compared, and the reproducibility at baseline and from duplicate measurements at each challenge step was determined.

PATIENTS

One hundred five children with newly diagnosed asthma, aged 5 to 10 years.

RESULTS

Compared to PEF, FEV(1) showed better baseline reproducibility (p = 0.002) and higher sensitivity (p < 0.0001) during challenge testing, determined as the change normalized to the baseline variation, while the forced expiratory volumes were not significantly different in these respects. During challenge testing in subjects with acceptable flow-volume tracings, paired recordings of FEV(1) agreed within 0.1 L in 85% and within 0.2 L in 93% of measurements. During challenge testing, the reproducibility of FEV(1) measurements was not better than that of the other indexes. Failure to exhale long enough precluded the use of FEV(1) in 16 of the children, particularly the youngest children.

CONCLUSIONS

The results demonstrated that the recently published guidelines for FEV(1) measurements during challenge tests can be applied to children. During challenge tests in asthmatic children, the advantage of the shorter fractions of forced expiratory volume was that they were more often acceptably recorded than FEV(1), while they showed as good reproducibility and were also equally sensitive in assessing changes in airway obstruction.

Disturbances in airflow dynamics and tracheal sounds during forced and quiet breathing in subjects with unilateral vocal fold paralysis

Variable extra thoracic obstruction has been found in spirometric studies in subjects with unilateral vocal fold paralysis. The aim of the study was to further evaluate airflow dynamics in these subjects with body plethysmography and tracheal sound analysis. Ten patients with unilateral vocal fold paralysis without a history of chronic pulmonary diseases and 10 healthy control subjects were studied. Flow-volume spirometry, body plethysmography and tracheal sound analysis were performed within 1 day. The study shows that peak inspiratory flow (PIF) and specific airway conductance (SG(aw)) expressed as percentage of Finnish reference values were significantly lower and airway resistance (R(aw)) was higher among the patients than among the controls (P=0.004, P=0.026 and P=0.004, respectively). The patients had higher sound amplitude of both inspiratory and expiratory tracheal sounds than the controls [root mean square (RMS) values of the power spectra were 31.5 and 25 dB, P=0.006 in inspiration and 31.5 and 26 dB, P=0.013 in expiration, respectively]. Quartile frequencies (F25 and F50) and RMS of expiratory tracheal sounds had significant negative correlation with PIF (P=0.02, P<0.001, P=0.02, respectively) and forced inspiratory volume in 1 s (FIV(1)) (P=0.01, P<0.001, P=0.01, respectively). There was also an association between F50 and peak expiratory flow (PEF) (P=0.02). According to the present study, both quiet breathing and forced inspiration are disturbed in subjects with unilateral vocal fold paralysis. A close relationship between tracheal sounds and respiratory function tests exists.

Tracheal sounds and airflow dynamics in surgically treated unilateral vocal fold paralysis

The aim of this study was to investigate the changes in tracheal sounds and airflow dynamics in patients who underwent surgical medialization of a unilaterally paralysed vocal fold. Ten adults with unilateral vocal fold paralysis but no history of pulmonary diseases were included. Vocal fold medialization was performed by an injection of autologous fascia into the paralysed vocal fold. Recording of tracheal sounds, flow-volume spirometry and body plethysmography were carried out before and 4-14 months after the operation. The mean number of inspiratory wheezes per respiratory cycle increased from 0.02 (range 0-0.10) to 0.42 (range 0-0.86) and the mean number of expiratory wheezes per respiratory cycle from 0.03 (range 0-0.20) to 0.36 (range 0-0.89). The increment was statistically significant (P=0.03 and P=0.04, respectively). The mean expiratory sound amplitude, in terms of root mean square (RMS), increased from 31.5 dB (range 24.0-38.0) to 34.9 dB (range 25-42) (P=0.03) and the average peak inspiratory flow (PIF) decreased from 4.63 l s-1 (range 2.84-7.51) to 4.03 l s-1 (range 2.27-6.68) (P=0.01). The results indicate that when the paralysed vocal fold is brought into midline by a surgical procedure, the prevalence of inspiratory and expiratory wheezes increases and sound intensity rises. According to this preliminary data tracheal sound analysis gives additional information for the assessment of the subtle changes in the larynx.

Lung function measured by the oscillometric method in prematurely born children with chronic lung disease

Premature birth is related to a chronic respiratory morbidity, which may persist until school-age. In these children, the forced oscillation technique would be suitable for evaluation of lung function even at preschool age, since it requires only minimal patient cooperation. In order to investigate the oscillometric findings related to premature birth, using the oscillation technique and conventional lung function methods 49 school-aged children born prematurely with (n=15) or without (n=34) chronic lung disease (CLD), and 18 healthy children born at full term were studied. Children with CLD had higher respiratory resistance (Rrs,5) and lower reactance (Xrs,5) than prematurely born children without CLD or healthy controls. Both Rrs,5 (r=-0.55, p<0.0001) and Xrs,5 (r=0.76, p<0.0001) were significantly associated with forced expiratory volume in one second (FEV1), the agreement with spirometry being better in Xrs,5 than in Rrs,5 (p=0.02). Rrs,5 was significantly related to airway resistance (Raw) measured by body plethysmography (r=0.63, p<0.0001), but underestimated resistance at high values of Raw. There was no significant relationship between the pulmonary diffusing capacity and the oscillometric findings. Compared to conventional methods, the oscillometric method yields concordant information on the severity of lung function deficit in children born prematurely, with or without chronic lung disease. In these children, the oscillometric findings are probably due to peripheral or more widespread airway obstruction. As conventional methods are not usually suitable for preschool children, oscillometry may serve as an alternative for early evaluation of chronic lung disease among children with premature birth in clinical or research settings.

Orthostatic increase of respiratory gas exchange in hyperventilation syndrome

BACKGROUND

Hyperventilation syndrome (HVS) is a common disorder which is difficult to diagnose because of somatic symptoms and its episodic nature. In previous studies respiratory alkalosis in arterial blood was often found during orthostatic tests in patients with HVS. The purpose of this study was to assess these orthostatic changes by non-invasive pulmonary gas exchange measurements and to evaluate whether these responses discriminate patients with HVS from healthy subjects.

METHODS

Respiratory gases were collected with a face mask and pulmonary gas exchange was measured after 10 minutes at rest and after eight minutes standing upright in 16 patients with HVS and 13 healthy control subjects. In patients with HVS arterial blood samples were also drawn at rest and in the standing position.

RESULTS

At rest the variables of respiratory gas exchange did not differ significantly between the groups. As a response to standing, minute ventilation increased in both study groups but significantly more in the patients with HVS (mean difference 5.4 l/min (95% CI 1.1 to 9.6)). The changes in end tidal CO(2) fraction (FETCO(2)) and in ventilatory equivalents for oxygen (VE/VO(2)) and for CO(2) (VE/VCO(2)) during the orthostatic test were also significantly larger in patients with HVS than in healthy controls. During standing FETCO(2) was significantly lower (mean difference -1.1 kPa; 95% CI -1.5 to -0.6) and VE/VO(2) (mean difference 18.4; 95% CI 7.7 to 29.0) and VE/VCO(2) (mean difference 11.7; 95% CI 4.8 to 18.6) were significantly higher in HVS patients than in healthy controls. By using the cut off level of 4% for FETCO(2) the sensitivity and specificity of the test to discriminate HVS were 87% and 77%, respectively, and by using the cut off level of 37 for VE/VO(2) they were 93% and 100%, respectively. In the HVS patients arterial PCO(2) and FETCO(2) were closely correlated during the orthostatic test (r = 0.93, p<0.0001).

CONCLUSIONS

As a response to change in body position from supine to standing, patients with HVS have an accentuated increase in ventilation which distinguishes them from healthy subjects. These findings suggest that non-invasive measurements of pulmonary gas exchange during orthostatic tests are useful in the clinical evaluation of patients with hyperventilation disorders.

Metered dose inhaler add-on devices: is the inhaled mass of drug dependent on the size of the infant?

Limited cooperation and low tidal volumes in infants make aerosol therapy difficult. We measured the amount of drug delivered from two baby spacer devices especially developed for use in infants. Designed as a randomized crossover study, aerolized budesonide from a pressurized metered dose inhaler (pMDI) was collected in the inspiratory filter interposed between the face mask and the spacer in 13 infants aged from 2 to 19 months old. The study was performed in connection with pulmonary function testing with a plethysmograph, and the children were sedated with cloral hydrate. Two small-volume baby spacer devices were used: a Babyhaler spacer (GlaxoWellcome, Hertfordshire, UK) made of polycarbonate with a volume of 350 mL and a built-in dead space of 40 mL and a NebuChamber spacer (AstraZeneca, Lund, Sweden) made of stainless steel with a volume of 250 mL and no dead space. Budesonide delivery from the NebuChamber was significantly higher than from the Babyhaler: 38.2% (range, 28.3%-47.5%) of the nominal dose versus 12% (range, 3.3%-21.25%) of the nominal dose of 400 micrograms of budesonide (P = 0.002). The inhaled mass of budesonide from the Babyhaler correlated significantly with skin surface area (r = 0.68, P = 0.018), weight (r = 0.66, P = 0.019), height (r = 0.69; P = 0.017), tidal volume (r = 0.82; P = 0.004), and minute volume (r = 0.67; P = 0.019). No correlations were found between these variables and the inhaled mass of budesonide from the NebuChamber. The results indicate that the design of the NebuChamber spacer affords stable drug delivery in infants and that a large variability in the inhaled mass of drug may be found when infants are inhaling from different baby spacers.

Intraindividual variability of infant whole-body plethysmographic measurements: effects of age and disease

The intraindividual variability of whole-body plethysmographic measurements was studied in a large series of consecutive infants (N = 144), divided into two groups: a group of infants born very prematurely (PM, N = 63), with (N = 28) or without (N = 35) a history of bronchopulmonary dysplasia (BPD), and a group of infants with persistent respiratory symptoms (PRS, N = 81), i.e., wheezing (N = 53) or cough (N = 28). The intraindividual variability was determined within each test and between tests, separated by a 10-min interval. In both study groups, the between-test variability was significantly larger than that within tests. Expressed as the median coefficient of variation (CV), the between-test repeatabilities in the PRS group were 8.0% for thoracic gas volume (TGV), 17.5% for airway resistance (Raw), and 18.4% for specific airway conductance (sGaw), and in the PM group, 8.9% for TGV, 20.4% for Raw, and 20.7% for sGaw. However, the individual range of CVs was large, ranging from 3 to 19% for TGV and from 5 to 55% for sGaw. With respect to TGV, the difference between the groups was statistically significant (P = 0.03). In infants with a history of BPD, there was also a significant negative age dependency in CVs of sGaw (r = -0.50, P = 0. 009), showing larger variation among younger individuals. The presenting symptom (wheezing or cough) in the PRS group did not influence the measurement variability significantly, and neither did the degree of bronchial obstruction. We conclude that on a group basis, the repeatability of infant body plethysmographic measurements may be satisfactory for scientific studies demonstrating pharmacodynamic effects; however, the intraindividual measurement variability should be reported for each test conditions and for infant groups in each study. Due to the large range in individual variation and the influence of age and disease processes on the variation, for an individual child there is only questionable benefit from a given measurement, unless the intrasubject, between-test variability is assessed individually before interventions, such as a bronchodilation test.

A new versatile PC-based lung sound analyzer with automatic crackle analysis (HeLSA); repeatability of spectral parameters and sound amplitude in healthy subjects

A versatile PC-based lung sound analyzer has been developed for short-term recording and analysis of respiratory sounds in research and clinical applications. The system consists of two sound sensors, a flow sensor, a filtering signal amplifier and a PC with a data acquisition card and software for measurement and analysis of the sounds. The analyses include phonopneumography, time expanded waveform analysis, spectral analysis with time averaged Fast Fourier Transform, frequency analysis in time domain (sonogram), and automatic detection and waveform analysis of crackles. Short-term repeatability of spectral parameters of tracheal and lung sounds was studied in 10 healthy subjects. The coefficients of variation (CoV) of the averaged quartile frequencies (F25, F50 and F75) of lung sounds during flow-controlled tidal breathing were 3.7, 4.0 and 8.9% in expiration and 2.7, 3.5 and 4.5% in inspiration, respectively. CoVs of the averaged F25, F50 and F75 of expiratory tracheal sounds were 6.9, 3.0 and 2.4%, and those of inspiratory tracheal sounds 6.3, 2.6 and 3.3%, respectively. Examples of lung sound analysis of samples containing adventitious sounds such as crackles and wheezes are presented. The results indicate that the median frequency has the best repeatability of quartile frequencies of breath sounds and they suggest that the variations of those parameters are low enough for diagnostic purposes. The results also suggest that the analyzer can be a useful new tool for pulmonary research in the fields of physiological and clinical short-term studies of respiratory sounds.

Averaged and time-gated spectral analysis of respiratory sounds. Repeatability of spectral parameters in healthy men and in patients with fibrosing alveolitis

STUDY OBJECTIVE

To obtain a basis for assessment of changes in breath sound spectra in patients with pulmonary diseases, short-term and day-to-day repeatability of spectral parameters was studied.

DESIGN

Breath sounds were recorded simultaneously from the trachea and from the chest twice at an interval of 15 min (short-term repeatability) and of 1 to 3 days (day-to-day repeatability). During recordings, air flow at the mouth was controlled, the target inspiratory and expiratory peak flow being 1.25 L/s. Inspiratory and expiratory breath sound spectra were averaged over 7 to 10 successive respiratory cycles. The repeatability of sound intensity (RMS), frequency of maximum intensity (Fmax), and median frequency (F50) was analyzed with analysis of variance.

PARTICIPANTS

Short-term repeatability was studied in 10 healthy nonsmoking men (age 25 to 44 years), and day-to-day repeatability was studied in 10 healthy nonsmoking men (age 23 to 41 years) and in 12 patients with clinically stable fibrosing alveolitis (age 35 to 82 years).

RESULTS

Short-term coefficient of variation (CoV) of Fmax and F50 was 2.6 to 6.7% when recorded from the chest, and 6.2 to 8.7% when recorded from the trachea. Day-to-day CoV of Fmax and F50 in healthy subjects was 4.7 to 8.5% and 5.0 to 8.7% recorded from the chest or from the trachea, respectively. Inspiratory day-to-day variation in those parameters was higher in patients with fibrosing alveolitis. CoV of RMS was high, ranging from 18 to 47% in different subject groups and sampling situations.

CONCLUSIONS

Repeatability of F50 of averaged flow-controlled lung sound spectra is good both in healthy subjects and in patients with fibrosing alveolitis. Thus, F50 of respiratory sound spectra may be useful in monitoring of changes induced by respiratory diseases and interventions. These results emphasize the importance of standardization of recording conditions and of analyzing techniques.

Classification of lung sounds in patients with asthma, emphysema, fibrosing alveolitis and healthy lungs by using self-organizing maps

The performance of the self-organizing map (SOM), an artificial neural network, was evaluated in the classification of lung sounds. Patients with asthma (n = 8), emphysema (n = 8) and fibrosing alveolitis (n = 8), and patients with healthy lungs (n = 8) were selected for the study. Fast Fourier transform (FFT) spectra from midinspiratory breath sounds recorded at the right lower lobe area were used to construct feature vectors in the learning and classification process of SOM. The sound segments did not contain wheezing sounds. The lung sounds of 25/32 (78%) patients were classified correctly, with an overall kappa (kappa) value of 0.71. The agreement between the clinical and proposed diagnoses based on classification of lung sounds was good among patients with emphysema (kappa = 0.92) and those with healthy lungs (kappa = 0.83), but only moderate among patients with asthma (kappa = 0.52) and fibrosing alveolitis (kappa = 0.54). This is due to the limitations in distinguishing breath sounds of asthmatics without wheezing sounds from those with crackles in fibrosing alveolitis by the spectral pattern alone. The results indicate that SOM based on FFT spectra is potentially useful in the classification of lung sounds, e.g. in health screening or in differential diagnosis of pulmonary disorders. To enhance the performance of SOM, other features of lung sounds should be combined with FFT spectra.

Significant differences in flow standardised breath sound spectra in patients with chronic obstructive pulmonary disease, stable asthma, and healthy lungs

BACKGROUND

Spectral characteristics of breath sounds in asthma and chronic obstructive pulmonary disease (COPD) have not previously been compared, although the structural differences in these disorders might be reflected in breath sounds.

METHODS

Flow standardised inspiratory breath sounds in patients with COPD (n = 17) and stable asthma (n = 10) with significant airways obstruction and in control patients without any respiratory disorders (n = 11) were compared in terms of estimates of the power spectrum. Breath sounds were recorded simultaneously at the chest and at the trachea.

RESULTS

The median frequency (F50) of the mean (SD) breath sound spectra recorded at the chest was higher in asthmatics (239 (19) Hz) than in both the control patients (206 (14) Hz) and the patients with COPD (201 (21) Hz). The total spectral power of breath sounds recorded at the chest in terms of root mean square (RMS) was higher in asthmatics than in patients with COPD. In patients with COPD the spectral parameters were not statistically different from those of control patients. The F50 recorded at the trachea in the asthmatics was significantly related to forced expiratory volume in one second (FEV1) (r = -0.77), but this was not seen in the other groups.

CONCLUSIONS

The observed differences in frequency content of breath sounds in patients with asthma and COPD may reflect altered sound generation or transmission due to structural changes of the bronchi and the surrounding lung tissue in these diseases. Spectral analysis of breath sounds may provide a new non-invasive method for differential diagnosis of obstructive pulmonary diseases.

Frequency distribution of breath sounds as an indicator of bronchoconstriction during histamine challenge test in asthmatic children

In order to study changes in respiratory sounds associated with acute bronchoconstriction and -dilatation, breath sounds of 11 children with asthma (age range, 10-14 years) were recorded at the chest and at the trachea during histamine challenge test and after subsequent bronchodilatation. The changes in frequency spectra of breath sounds were compared with simultaneous changes in forced expiratory volume in 1 second (FEV1). In seven children who responded to histamine with a decrease in FEV1 of more than 15%, there was a significant relationship between percentage change in FEV1 (delta FEV1) and percentage change in median frequency (delta F50) of expiratory breath sounds recorded at the chest (r = 0.865; beta = -0.706, P = 0.0001) and at the trachea (r = 0.888; beta = -1.12, P = 0.0001). The association between breath sound intensity and FEV1 was weaker. Based on ANOVA, the increase of F50 during the challenge test was significantly larger in children who responded to histamine than in those who were non-responsive (P = 0.0016). At the chest, a decrease of 15% in FEV1 corresponded to an increase of 8% in expiratory F50. The provocative dose of histamine inducing a decrease of 15% in FEV1 (PD15FEV1) and the provocative dose causing an increase of 8% in F50 (PD8F50) were significantly related (r = 0.927, P = 0.003). We conclude that spectral analysis of breath sounds can be used to indicate airway obstruction during bronchial challenge tests in children, and may be adapted for tests in pre-school children. The results suggest that the same mechanisms that induce airflow limitation due to inhaled histamine may generate an increase in frequency content of breath sounds in children with asthma.

Changes in frequency spectra of breath sounds during histamine challenge test in adult asthmatics and healthy control subjects

Air-flow standardized breath sounds were recorded at the chest and at the trachea during histamine challenge test and after subsequent bronchodilation in 12 asthmatics and 6 healthy controls for spectral analysis, to be compared with simultaneous changes in spirometric variables. Of all the lung sound variables measured, the changes in median frequency of the power spectrum (F50) of tracheal expiratory sounds were found to correlate best (r = 0.853, p < 0.0001) with changes in FEV1. The increase of F50 during histamine challenge was significantly larger in asthmatics than in healthy control subjects (p < 0.005). The provocative dose of histamine inducing a decrease of 15 percent in FEV1 (PD15FEV1) and the provocative dose causing an increase of 30 percent in tracheal expiratory F50 (PD30F50) were significantly related (r = 0.754, p = 0.012). In asthmatics, the breath sound frequency distribution in terms of median frequency reflected acute changes in airways obstruction with high sensitivity and specificity. The present method for breath sound analysis can be applied for patients with limited cooperation during bronchial challenge tests.

A rapid dosimetric method with controlled tidal breathing for histamine challenge. Repeatability and distribution of bronchial reactivity in a clinical material

A rapid dosimetric method with controlled tidal breathing for histamine challenge was evaluated by assessment of its repeatability, by comparing to a present nondosimetric standard method, and by application to adult patients with recent asthma (n = 31), chronic asthma (n = 33), chronic cough (n = 71) or chronic rhinitis (n = 41) and to healthy controls (n = 31). An automatic inhalation-synchronized dosimetric jet nebulizer with a known lung deposition of the aerosol was used to administer histamine and to control breathing. The non-cumulative doses of histamine diphosphate were 0.025, 0.1, 0.4 and 1.6 mg, administered during 0.4 s following tidal inspiration of 100 ml of air. The test procedure required 1 inhalation of histamine 4 mg/ml and followed by 1, 4 and 16 inhalations of histamine 16 mg/ml from the device, and its duration was about 30 minutes. The intraindividual correlation coefficient of the histamine dose causing a reduction of 15 percent in FEV1 (PD15FEV1) on 2 consecutive days in 14 asthmatic subjects was 0.937; the standard error of the single determination was 13 percent of the mean PD15 FEV1. A PD15FEV1 value below 0.4 mg was found only in asthmatic subjects; in chronic asthma, below 0.5 mg; in recent asthma, between 0.1 mg and 1.6 mg or more. In patients with chronic cough and chronic rhinitis, 20 and 32 percent, respectively, the PD15FEV1 values between 0.4 and 1.6 mg, the other patients in these groups were non-responsive. In all healthy control subjects, the PD15FEV1 was over 1.0 mg, 80 percent of them were nonresponsive to the maximum 1.6 mg dose. This new test allows rapid, accurate, and quantitative assessment of bronchial responsiveness to histamine.

Accuracy and repeatability of a pocket turbine spirometer: comparison with a rolling seal flow-volume spirometer

The accuracy and repeatability of a recently introduced pocket spirometer (Micro Spirometer; Micro Medical Instruments Ltd, Rochester, UK) was evaluated. FEV1 and FVC values obtained with this instrument were compared with those measured with a rolling-seal flow-volume spirometer (CPI 220 with microcomputer) in 31 patients and 11 healthy volunteers. In the whole material, expressed as mean +/- SD, the pocket spirometer recorded 0.44 +/- 0.23 l (13 +/- 7%) smaller values for FEV1 (P < 0.001) and 0.64 +/- 0.48 l (15 +/- 11%) smaller values for FVC (P < 0.001) than the rolling-seal spirometer. The short-term repeatability of the measurements expressed as the coefficient of variation of repeated measurements using the pocket spirometer was 2.2% for FEV1 and 2.3% for FVC in a series of 10 healthy subjects and 10 patients with COPD. It is concluded that the underestimation of FEV1 and FVC of the pocket spirometer was too large and inconsistent for the device to be used interchangeably with conventional spirometers. However, the repeatability of the measurements with the pocket spirometer is close to that reported previously for flow-volume spirometry. Thus the pocket spirometer may be suitable in assessing acute changes of spirometric indices e.g. during provocation tests or during patient follow-up in asthma.