Automatic wheeze detection based on auditory modelling

Automatic wheeze detection has several potential benefits compared with reliance on human auscultation: it is experience independent, an automated historical record can easily be kept, and it allows quantification of wheeze severity. Previous attempts to detect wheezes automatically have had partial success but have not been reliable enough to become widely accepted as a useful tool. In this paper an improved algorithm for automatic wheeze detection based on auditory modelling is developed, called the frequency- and duration-dependent threshold algorithm. The mean frequency and duration of each wheeze component are obtained automatically. The detected wheezes are marked on a spectrogram. In the new algorithm, the concept of a frequency- and duration-dependent threshold for wheeze detection is introduced. Another departure from previous work is that the threshold is based not on global power but on power corresponding to a particular frequency range. The algorithm has been tested on 36 subjects, 11 of whom exhibited characteristics of wheeze. The results show a marked improvement in the accuracy of wheeze detection when compared with previous algorithms

Measurement of bronchial hyperreactivity : comparison of three Nordic dosimetric methods

Clinical testing of bronchial hyperreactivity (BHR) provides valuable information in asthma diagnostics. Nevertheless, the test results depend to a great extent on the testing procedure: test substance, apparatus and protocol. In Nordic countries, three protocols predominate in the testing field: Per Malmberg, Nieminen and Sovijarvi methods. However, knowledge of their equivalence is limited. We aimed to find equivalent provocative doses (PD) to obtain similar bronchoconstrictive responses for the three protocols. We recruited 31 patients with suspected asthma and health care workers and performed BHR testing with methacholine according to Malmberg and Nieminen methods, and with histamine according to Sovijarvi. We obtained the individual response-dose slopes for each method and predicted equivalent PD values. Applying a mixed-model, we found significant differences in the mean (standard error of mean) response-dose (forced expiratory volume in one second (FEV1)%/mg): Sovijarvi 7.2 (1.5), Nieminen 13.8 (4.2) and Malmberg 26 (7.3). We found that the earlier reported cut-point values for moderate BHR and marked BHR between the Sovijarvi (PD15) and Nieminen (PD20) methods were similar, but with the Malmberg method a significant bronchoconstrictive reaction was measured with lower PD20 values. We obtained a relationship between slope values and PD (mg) between different methods, useful in epidemiological research and clinical practice.Peer reviewe

Restriction of lung volumes but normal function of pulmonary tissue in mulibrey nanism

Background Mulibrey nanism (MUL) is a rare growth restriction disorder with multiple organ manifestations caused by genetic defects affecting the TRIM37 protein. A perimyocardial heart disease is the most serious manifestation. Many MUL children appear to suffer from airway obstruction related to infection or exercise, prompting use of inhaled therapies. Asthma medication is continued up to adolescence or even to adulthood due to persisting of symptoms. The pulmonary pathophysiology has previously not been evaluated in any MUL cohort. Methods Thirty three finnish MUL patients (median age 20 years) were investigated with several lung function tests: spirometry with bronchodilatation test, single-breath diffusing capacity for carbon monoxide, single-breath lung volume measurements with helium dilution, and thoracic gas volume, airway resistance and specific conductance measurements with a body plethysmograph. As MUL typically affects body proportions, all variables were compared with reference values and with predicted values calculated from sitting height. Results Total lung capacity and forced vital capacity were markedly reduced (total lung capacity [TLC] and forced vital capacity [FVC], P = 12% and >= 200 mL) was found only in one patient. Conclusion MUL patients typically have volume restriction of the lungs, but function of the pulmonary tissue remains intact. Evidence of asthma in lung function testing at adult age is rare.Peer reviewe

Reference values of spirometry for Finnish adults

BackgroundDiagnostic assessment of lung function necessitates up-to-date reference values. The aim of this study was to estimate reference values for spirometry for the Finnish population between 18 and 80years and to compare them with the existing Finnish, European and the recently published global GLI2012 reference values. MethodsSpirometry was performed for 1380 adults in the population-based FinEsS studies and for 662 healthy non-smoking volunteer adults. Detailed predefined questionnaire screening of diseases and symptoms, and quality control of spirometry yielded a sample of 1000 native Finns (387 men) healthy non-smokers aged 18-83years. Sex-specific reference values, which are estimated using the GAMLSS method and adjusted for age and height, are provided. ResultsThe predicted values for lung volumes are larger than those obtained by GLI2012 prediction for the Caucasian subgroup for forced vital capacity (FVC) by an average 62% and 51% and forced expiratory volume in 1s (FEV1) by an average 42% and 30% in men and women, respectively. GLI2012 slightly overestimated the ratio FEV1/FVC with an age-dependent trend. Most reference equations from other European countries, with the exception of the Swiss SAPALDIA study, showed an underestimation of FVC and FEV1 to varying degrees, and a slight overestimation of FEV1/FVC. ConclusionThis study offers up-to-date reference values of spirometry for native Finns with a wide age range. The GLI2012 predictions seem not to be suitable for clinical use for native Finns due to underestimation of lung volumes.Peer reviewe

Computerized respiratory sound analysis in people with dementia: a first-step towards diagnosis and monitoring of respiratory conditions

Computerized respiratory sound analysis has been shown to be an objective and reliable way to assess respiratory diseases. However, its application in non-collaborative populations, such as people with dementia, is still unknown. Therefore this study aimed to characterize normal and adventitious respiratory sounds (NRS; ARS) in older people with and without dementia. A cross-sectional study including two groups of 30 subjects with dementia and 30 subjects without dementia was performed. Digital auscultation was used to record NRS and ARS per breathing-phase (inspiration/expiration) at trachea and thorax. Frequency at percentiles 25, 50 and 75, frequency at maximum-intensity, maximum-intensity (I max) and mean-intensity (I mean) characterized NRS. Crackle number, frequency, initial-deflection-width, 2cycle-duration, and largest-deflection-width and wheeze number, frequency and occupation-rate characterized ARS. Groups were similar in socio-demographics, except for anthropometrics. No significant differences were found between groups in NRS frequency or ARS at trachea or thorax. Significant lower I max (inspiration: 36.88(29.42;39.92) versus 39.84(36.50;44.17) p  =  0.007; expiration: 34.51(32.06;38.87) versus 42.33(36.92;44.98) p  <  0.001) and I mean (inspiration: 15.23(12.08;18.60) versus 18.93(15.64;21.82) p  =  0.003 and expiration: 14.57(12.08;18.30) versus 18.87(15.64;21.44) p  =  0.001) at trachea and higher I mean (inspiration: 17.29(16.04;19.31) versus 16.45(15.05; 18.79) p  =  0.005 and expiration: 16.71(15.31;18.56) versus 16.38(14.40;17.85) p  =  0.011) at thorax were found in subjects with dementia when compared with subjects without dementia. To conclude, people with and without dementia had similar NRS and ARS characteristics, except for NRS intensity. Computerized respiratory sound analysis was feasible in a non-collaborative population. Further research is needed to enhance the use of respiratory acoustics in non-collaborative populations, with strong potential to be applied in different settings for diagnosis and monitoring purposes

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 13healthy 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 (V̇E/V̇O(2)) and for CO(2) (V̇E/V̇CO(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 V̇E/V̇O(2) (mean difference 18.4; 95% CI 7.7to 29.0) and V̇E/V̇CO(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 V̇E/V̇O(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.


Sustained reduction in bronchial hyperresponsiveness with inhaled fluticasone propionate within three days in mild asthma: time course after onset and cessation of treatment

Background: Bronchial hyperresponsiveness (BHR) is characteristic of asthmatic airways, is induced by airway inflammation, and is reduced by inhaled corticosteroids (ICS). The time course for the onset and cessation of the effect of ICS on BHR is unclear. The effect of inhaled fluticasone propionate (FP) on BHR in patients with mild persistent asthma was assessed using time intervals of hours, days and weeks. Methods: Twenty six asthmatic patients aged 21–59 years were selected for this randomised, double blind, parallel group study. The effect of 250 µg inhaled FP (MDI) administered twice daily was compared with that of placebo on BHR assessed using a dosimetric histamine challenge method. The dose of histamine inducing a decrease in forced expiratory volume in 1 second (FEV(1)) by 15% (PD(15)FEV(1)) was measured before and 6, 12, 24 and 72 hours, and 2, 4 and 6 weeks after starting treatment, and 48 hours, 1 week and 2 weeks after cessation of treatment. Doubling doses of changes in PD(15)FEV(1) were calculated and area under the curve (AUC) statistics were used to summarise the information from individual response curves. Results: The increase in PD(15)FEV(1) from baseline was greater in the FP group than in the placebo group; the difference achieved significance within 72 hours and remained significant until the end of treatment. In the FP group PD(15)FEV(1) was 1.85–2.07 doubling doses above baseline between 72 hours and 6 weeks after starting treatment. BHR increased significantly within 2 weeks after cessation of FP treatment. Conclusions: A sustained reduction in BHR to histamine in patients with mild asthma was achieved within 3 days of starting treatment with FP at a daily dose of 500 µg. The effect tapered within 2 weeks of cessation of treatment