"Velcro-type" crackles predict specific radiologic features of fibrotic interstitial lung disease.

BACKGROUND: "Velcro-type" crackles on chest auscultation are considered a typical acoustic finding of Fibrotic Interstitial Lung Disease (FILD), however whether they may have a role in the early detection of these disorders has been unknown. This study investigated how "Velcro-type" crackles correlate with the presence of distinct patterns of FILD and individual radiologic features of pulmonary fibrosis on High Resolution Computed Tomography (HRCT). METHODS: Lung sounds were digitally recorded from subjects immediately prior to undergoing clinically indicated chest HRCT. Audio files were independently assessed by two chest physicians and both full volume and single HRCT sections corresponding to the recording sites were extracted. The relationships between audible "Velcro-type" crackles and radiologic HRCT patterns and individual features of pulmonary fibrosis were investigated using multivariate regression models. RESULTS: 148 subjects were enrolled: bilateral "Velcro-type" crackles predicted the presence of FILD at HRCT (OR 13.46, 95% CI 5.85-30.96, p < 0.001) and most strongly the Usual Interstitial Pneumonia (UIP) pattern (OR 19.8, 95% CI 5.28-74.25, p < 0.001). Extent of isolated reticulation (OR 2.04, 95% CI 1.62-2.57, p < 0.001), honeycombing (OR 1.88, 95% CI 1.24-2.83, < 0.01), ground glass opacities (OR 1.74, 95% CI 1.29-2.32, p < 0.001) and traction bronchiectasis (OR 1.55, 95% CI 1.03-2.32, p < 0.05) were all independently associated with the presence of "Velcro-type" crackles. CONCLUSIONS: "Velcro-type" crackles predict the presence of FILD and directly correlate with the extent of distinct radiologic features of pulmonary fibrosis. Such evidence provides grounds for further investigation of lung sounds as an early identification tool in FILD.

An algorithm to detect dicrotic notch in arterial blood pressure and photoplethysmography waveforms using the iterative envelope mean method.

BACKGROUND AND OBJECTIVE: Detection of the dicrotic notch (DN) within a cardiac cycle is essential for assessment of cardiac output, calculation of pulse wave velocity, estimation of left ventricular ejection time, and supporting feature-based machine learning models for noninvasive blood pressure estimation, and hypotension, or hypertension prediction. In this study, we present a new algorithm based on the iterative envelope mean (IEM) method to detect automatically the DN in arterial blood pressure (ABP) and photoplethysmography (PPG) waveforms. METHODS: The algorithm was evaluated on both ABP and PPG waveforms from a large perioperative dataset (MLORD dataset) comprising 17,327 patients. The analysis involved a total of 1,171,288 cardiac cycles for ABP waveforms and 3,424,975 cardiac cycles for PPG waveforms. To evaluate the algorithm's performance, the systolic phase duration (SPD) was employed, which represents the duration from the onset of the systolic phase to the DN in the cardiac cycle. Correlation plots and regression analysis were used to compare the algorithm against marked DN detection, while box plots and Bland-Altman plots were used to compare its performance with both marked DN detection and an established DN detection technique (second derivative). The marking of the DN temporal location was carried out by an experienced researcher using the help of the 'find_peaks' function from the scipy Python package, serving as a reference for the evaluation. The marking was visually validated by both an engineer and an anesthesiologist. The robustness of the algorithm was evaluated as the DN was made less visually distinct across signal-to-noise ratios (SNRs) ranging from -30 dB to -5 dB in both ABP and PPG waveforms. RESULTS: The correlation between SPD estimated by the algorithm and that marked by the researcher is strong for both ABP (R2(87,343) =0.99, p<.001) and PPG (R2(86,764) =0.98, p<.001) waveforms. The algorithm had a lower mean error of DN detection (s): 0.0047 (0.0029) for ABP waveforms and 0.0046 (0.0029) for PPG waveforms, compared to 0.0693 (0.0770) for ABP and 0.0968 (0.0909) for PPG waveforms for the established 2nd derivative method. The algorithm has high rate of detectability of DN detection for SNR of >= -9 dB for ABP waveforms and >= -12 dB for PPG waveforms indicating robust performance in detecting the DN when it is less visibly distinct. CONCLUSION: Our proposed IEM- based algorithm can detect DN in both ABP and PPG waveforms with low computational cost, even in cases where it is not distinctly defined within a cardiac cycle of the waveform ('DN-less signals'). The algorithm can potentially serve as a valuable, fast, and reliable tool for extracting features from ABP and PPG waveforms. It can be especially beneficial in medical applications where DN-based features, such as SPD, diastolic phase duration, and DN amplitude, play a significant role.

Are crackles an appropriate outcome measure for airway clearance therapy?

BACKGROUND: There is an urgent need to develop new outcome measures for respiratory therapy, to evaluate its effectiveness. Adventitious sounds generated from the lungs (crackles and wheezes), can now be quantified and characterized objectively with computer technology. To our knowledge, this is the first reported study designed to assess any change in lung crackles before and after a single session of airway clearance therapy. METHODS: Twenty-three stable bronchiectasis patients were recruited from United Kingdom out-patient clinics and treated with a single session of airway clearance therapy, using the active cycle of breathing technique. Sound recordings were made before and after the session at 7 anatomical chest locations. Computerized lung sound analysis was used to measure crackle parameters: 2-cycle deflection width (2CD), and crackle number per breath cycle (nBC). Perceived breathlessness, lung function, and oxygen saturation data were also recorded. RESULTS: Crackle mean 2CD and mean nBC increased post intervention. Sixteen participants (70%) showed a statistically significant difference in mean crackle 2CD before and after the session at ≥ 1 chest location. Thirteen (57%) participants had a difference between mean crackle 2CD before and after the intervention > 1 Smallest Real Difference (SRD, mean SRD = 2.23 ms) at ≥ 1 chest location. Differences in mean crackle nBC before and after the intervention did not exceed the SRD (mean SRD = 32 crackles per breath cycle) in any participant. Perceived breathlessness was significantly reduced post intervention; no significant changes were observed in either lung function or oxygen saturation. CONCLUSIONS: Crackle duration (2CD) was found to change after a single session of airway clearance therapy, and shows promise as a new outcome measure for respiratory therapy interventions.

Changes in quantifiable breathing pattern components predict asthma control: an observational cross-sectional study.

BACKGROUND: Breathing pattern disorders are frequently reported in uncontrolled asthma. At present, this is primarily assessed by questionnaires, which are subjective. Objective measures of breathing pattern components may provide additional useful information about asthma control. This study examined whether respiratory timing parameters and thoracoabdominal (TA) motion measures could predict and classify levels of asthma control. METHODS: One hundred twenty-two asthma patients at STEP 2- STEP 5 GINA asthma medication were enrolled. Asthma control was determined by the Asthma Control Questionnaire (ACQ7-item) and patients divided into 'well controlled' or 'uncontrolled' groups. Breathing pattern components (respiratory rate (RR), ratio of inspiration duration to expiration duration (Ti/Te), ratio of ribcage amplitude over abdominal amplitude during expiration phase (RCampe/ABampe), were measured using Structured Light Plethysmography (SLP) in a sitting position for 5-min. Breath-by-breath analysis was performed to extract mean values and within-subject variability (measured by the Coefficient of Variance (CoV%). Binary multiple logistic regression was used to test whether breathing pattern components are predictive of asthma control. A post-hoc analysis determined the discriminant accuracy of any statistically significant predictive model. RESULTS: Fifty-nine out of 122 asthma patients had an ACQ7-item < 0.75 (well-controlled asthma) with the rest being uncontrolled (n = 63). The absolute mean values of breathing pattern components did not predict asthma control (R2 = 0.09) with only mean RR being a significant predictor (p < 0.01). The CoV% of the examined breathing components did predict asthma control (R2 = 0.45) with all predictors having significant odds ratios (p < 0.01). The ROC curve showed that cut-off points > 7.40% for the COV% of the RR, > 21.66% for the CoV% of Ti/Te and > 18.78% for the CoV% of RCampe/ABampe indicated uncontrolled asthma. CONCLUSION: The within-subject variability of timing parameters and TA motion can be used to predict asthma control. Higher breathing pattern variability was associated with uncontrolled asthma suggesting that irregular resting breathing can be an indicator of poor asthma control.

The reliability of lung crackle characteristics in cystic fibrosis and bronchiectasis patients in a clinical setting.

Lung sounds provide useful information for assessing and monitoring respiratory patients, but standard auscultation is subjective. Computer aided lung sound analysis (CALSA) enables the quantification and characterisation of added lung sounds (e.g. crackles). At present, little is known about the reliability of these sound characteristics. Therefore, the aim of this study was to explore the reliability of crackle initial deflection width (IDW) and two-cycle deflection (2CD) in a clinical population. Fifty-four subjects (37 bronchiectasis, 17 cystic fibrosis) were recruited from out-patient clinics. Three repeated lung sound recordings were taken at seven anatomical sites with a digital stethoscope connected to a laptop computer. The intra-subject reliability of crackle IDW and 2CD was found to be 'good' to 'excellent', estimated by the analysis of variance, intraclass correlation coefficient (IDW 0.76;0.85, 2CD 0.83;0.94), Bland and Altman 95% limits of agreement (IDW -0.50;0.47 ms, 2CD -2.12;1.87 ms) and smallest real difference (IDW 0.30;0.66 ms, 2CD 1.57;2.42 ms). Crackle 2CD was found to be more reliable than IDW. It is concluded that crackle IDW and 2CD characterized by CALSA have good test-retest reliability. This technique requires further evaluation since CALSA has potential to diagnose or monitor respiratory conditions, and provide an objective physiological measure for respiratory interventions.

Motif Discovery in Speech: Application to Monitoring Alzheimer's Disease.

BACKGROUND: Perseveration - repetition of words, phrases or questions in speech - is commonly described in Alzheimer's disease (AD). Measuring perseveration is difficult, but may index cognitive performance, aiding diagnosis and disease monitoring. Continuous recording of speech would produce a large quantity of data requiring painstaking manual analysis, and risk violating patients' and others' privacy. A secure record and an automated approach to analysis are required. OBJECTIVES: To record bone-conducted acoustic energy fluctuations from a subject's vocal apparatus using an accelerometer, to describe the recording and analysis stages in detail, and demonstrate that the approach is feasible in AD. METHODS: Speech-related vibration was captured by an accelerometer, affixed above the temporomandibular joint. Healthy subjects read a script with embedded repetitions. Features were extracted from recorded signals and combined using Principal Component Analysis to obtain a one-dimensional representation of the feature vector. Motif discovery techniques were used to detect repeated segments. The equipment was tested in AD patients to determine device acceptability and recording quality. RESULTS: Comparison with the known location of embedded motifs suggests that, with appropriate parameter tuning, the motif discovery method can detect repetitions. The device was acceptable to patients and produced adequate signal quality in their home environments. CONCLUSION: We established that continuously recording bone-conducted speech and detecting perseverative patterns were both possible. In future studies we plan to associate the frequency of verbal repetitions with stage, progression and type of dementia. It is possible that the method could contribute to the assessment of disease-modifying treatments.

Evaluation of the agreement of tidal breathing parameters measured simultaneously using pneumotachography and structured light plethysmography.

Structured light plethysmography (SLP) is a noncontact, noninvasive, respiratory measurement technique, which uses a structured pattern of light and two cameras to track displacement of the thoraco-abdominal wall during tidal breathing. The primary objective of this study was to examine agreement between tidal breathing parameters measured simultaneously for 45 sec using pneumotachography and SLP in a group of 20 participants with a range of respiratory patterns ("primary cohort"). To examine repeatability of the agreement, an additional 21 healthy subjects ("repeatability cohort") were measured twice during resting breathing and once during increased respiratory rate (RR). Breath-by-breath and averaged RR, inspiratory time (tI), expiratory time (tE), total breath time (tTot), tI/tE, tI/tTot, and IE50 (inspiratory to expiratory flow measured at 50% of tidal volume) were calculated. Bland-Altman plots were used to assess the agreement. In the primary cohort, breath-by-breath agreement for RR was ±1.44 breaths per minute (brpm). tI, tE, and tTot agreed to ±0.22, ±0.29, and ±0.32 sec, respectively, and tI/tE, tI/tTot, and IE50/IE50SLP to ±0.16, ±0.05, and ±0.55, respectively. When averaged, agreement for RR was ±0.19 brpm. tI, tE, and tTot were within ±0.16, ±0.16, and ±0.07 sec, respectively, and tI/tE, tI/tTot, and IE50 were within ±0.09, ±0.03, and ±0.25, respectively. A comparison of resting breathing demonstrated that breath-by-breath and averaged agreements for all seven parameters were repeatable (P > 0.05). With increased RR, agreement improved for tI, tE, and tTot (P ≤ 0.01), did not differ for tI/tE, tI/tTot, and IE50 (P > 0.05) and reduced for breath-by-breath (P < 0.05) but not averaged RR (P > 0.05).

Advanced voice function assessment: editorial introduction to this special issue.

ICT COST Action 2103 was an EU-funded collaborative network of speech processing engineers, laryngologists, and phoniatricians that started on 19 December 2006 and ended on 18 June 2011. The main objectives were to improve the clinical assessment of voice using new technologies; to encourage clinicians and technologists to work closely together to understand the needs and limitations of each other's fields and, in parallel, to acquire new data with a view to elaborating better voice production models. The papers in this special issue represent some of the outcomes of that partnership. This editorial introduces the background and context for COST Action 2103 and each of the papers. In conclusion we discuss the impact of the Action and what aspects of it may have a lasting effect on practice.

The Relationship Between Crackle Characteristics and Airway Morphology in COPD.

BACKGROUND: Crackles in COPD are believed to be generated by the re-opening of collapsed airways, which result from chronic inflammation, secretions, and loss of cartilaginous support through inflammation. However, it is unclear whether crackle characteristics can be used to identify COPD. This is the first study to examine the relationship between specific added lung sounds (crackles) and measurements of conductive airways and emphysema score obtained from high-resolution computed tomography (HRCT) in vivo in humans. A predictive relationship might permit the use of lung sounds as a biomarker for COPD. METHODS: A convenience sample of 26 subjects was recruited into the study and consisted of 9 healthy non-smokers, 9 healthy smokers, and 8 subjects with mild or moderate COPD. Lung sound data were recorded using a digital stethoscope connected to a laptop computer. Airway diameter, emphysema score, and percentage of wall area were measured from HRCT scans. RESULTS: The analysis showed that there were no statistically significant differences in crackle characteristics (the number of crackles per breathing cycle and crackle 2-cycle duration) between the 3 subject groups. Both crackle 2-cycle duration and crackle number showed some significant correlation with airway parameters at some branch generations, but due to the large number of correlations performed, these were consistent with chance findings. CONCLUSIONS: Although there were some significant correlations between crackle characteristics and measurements of the conductive airways and emphysema score, the possibility that these correlations have occurred by chance cannot be ruled out. Therefore, this study provides no conclusive evidence that crackle characteristics are related to HRCT variables in COPD.

Aerodynamic measures of speech in unilateral vocal fold paralysis (UVFP) patients.

This paper reports the recording and analysis of an aerodynamic database of 51 words produced by four patients with unilateral vocal fold paralysis. The vowel-fricative-vowel boundaries were manually annotated, and the mean absolute oral airflow amplitude (OA), fundamental frequency (f0), and first formant intensity (IF1) were extracted from a 20 ms window in the steady state of each phone. A case study approach to analysis of phonatory behaviour for the subjects is presented. Significant differences were found between the absolute OA and IF1 for different phones. Large between-subject variations in absolute measures for OA and f0 were found. Relative values calculated from the difference in these parameters between phones show consistency for subjects of the same gender.

Articulatory capacity of Neanderthals, a very recent and human-like fossil hominin.

Scientists seek to use fossil and archaeological evidence to constrain models of the coevolution of human language and tool use. We focus on Neanderthals, for whom indirect evidence from tool use and ancient DNA appears consistent with an adaptation to complex vocal-auditory communication. We summarize existing arguments that the articulatory apparatus for speech had not yet come under intense positive selection pressure in Neanderthals, and we outline some recent evidence and analyses that challenge such arguments. We then provide new anatomical results from our own attempt to reconstruct vocal tract (VT) morphology in Neanderthals, and document our simulations of the acoustic and articulatory potential of this reconstructed Neanderthal VT. Our purpose in this paper is not to polarize debate about whether or not Neanderthals were human-like in all relevant respects, but to contribute to the development of methods that can be used to make further incremental advances in our understanding of the evolution of speech based on fossil and archaeological evidence.

In vitro experimental investigation of voice production.

The process of human phonation involves a complex interaction between the physical domains of structural dynamics, fluid flow, and acoustic sound production and radiation. Given the high degree of nonlinearity of these processes, even small anatomical or physiological disturbances can significantly affect the voice signal. In the worst cases, patients can lose their voice and hence the normal mode of speech communication. To improve medical therapies and surgical techniques it is very important to understand better the physics of the human phonation process. Due to the limited experimental access to the human larynx, alternative strategies, including artificial vocal folds, have been developed. The following review gives an overview of experimental investigations of artificial vocal folds within the last 30 years. The models are sorted into three groups: static models, externally driven models, and self-oscillating models. The focus is on the different models of the human vocal folds and on the ways in which they have been applied.