Breath Detection Research Articles

Diagnosis of Helicobacter pylori: Invasive and non-invasive tests

Helicobacter pylori infection can be diagnosed by invasive techniques requiring endoscopy and biopsy (e.g. histological examination, culture and rapid urease test) and by non-invasive techniques, such as serology, the urea breath test, urine/blood or detection of H. pylori antigen in stool specimen. Some non-invasive tests, such as the urea breath test and the stool antigen test, detect active infection: these are called 'active tests'. Non-invasive tests (e.g. serology, urine, near-patient tests) are markers of exposure to H. pylori but do not indicate if active infection is ongoing; these are 'passive tests'. Non-invasive test-and-treat strategies are widely recommended in the primary care setting. The choice of appropriate test depends on the pre-test probability of infection, the characteristics of the test being used and its cost-effectiveness.

An Effective Algorithm for Automatic Detection and Exact Demarcation of Breath Sounds in Speech and Song Signals

Automatic detection of predefined events in speech and audio signals is a challenging and promising subject in signal processing. One important application of such detection is removal or suppression of unwanted sounds in audio recordings, for instance in the professional music industry, where the demand for quality is very high. Breath sounds, which are present in most song recordings and often degrade the aesthetic quality of the voice, are an example of such unwanted sounds. Another example is bad pronunciation of certain phonemes. In this paper, we present an automatic algorithm for accurate detection of breaths in speech or song signals. The algorithm is based on a template matching approach, and consists of three phases. In the first phase, a template is constructed from mel frequency cepstral coefficients (MFCCs) matrices of several breath examples and their singular value decompositions, to capture the characteristics of a typical breath event. Next, in the initial processing phase, each short-time frame is compared to the breath template, and marked as breathy or nonbreathy according to predefined thresholds. Finally, an edge detection algorithm, based on various time-domain and frequency-domain parameters, is applied to demarcate the exact boundaries of each breath event and to eliminate possible false detections. Evaluation of the algorithm on a database of speech and songs containing several hundred breath sounds yielded a correct identification rate of 98% with a specificity of 96%

Automatic detection of sleep-disordered breathing from a single-channel airflow record

Single-channel airflow monitors developed for screening of sleep-disordered breathing (SDB) have conflicting results for accuracy. It was hypothesised that the analytical algorithm is crucial for the performance and the present authors tried to develop a novel computer algorithm. A total of 399 polysomnography (PSG) records were employed, including a thermal sensor signal. The first 100 records were used in the development of the algorithm and the remainder for validation. In addition, 119 PSG records, including a thermocouple signal and a nasal pressure signal, were used for the validation. The algorithm was designed to obtain a time series (flow-power) using power spectral analysis, which expresses fluctuation in the airflow signal amplitude. From the time series the algorithm detects transient falls of the flow-power and calculates flow-respiratory disturbance index (RDI), defined as the number of falls per hour. In the validation group, the areas under receiver operating characteristic curves for diagnosis of SDB (apnoea/hypopnoea index > or =5) were 0.96, 0.95 and 0.95, for the records of the thermal sensor, thermocouple and nasal pressure system, respectively. The diagnostic sensitivity/specificity ratios of the flow-RDI were 96/76, 88/80 and 97%/77%, respectively. The present results suggest that a single-channel airflow monitor can be used to detect sleep-disordered breathing automatically if the analytic algorithm is optimised.

Radar methods of detection of human breathing and heartbeat

Methods of extracting information from observations of human subjects by short-range radars with various types of probing signals are theoretically analyzed. The time and frequency features of breathing and heartbeat realizations obtained by different demodulation methods from monochromatic and video-pulse probing signals are considered. Algorithms for discrimination of signals reflected by human objects from interfering reflections from local objects are modeled for continuous probing signals with stepwise frequency modulation.

Pulse wave transit time for monitoring respiration rate

In this study, we investigate the beat-to-beat respiratory fluctuations in pulse wave transit time (PTT) and its subcomponents, the cardiac pre-ejection period (PEP) and the vessel transit time (VTT) in ten healthy subjects. The three transit times were found to fluctuate in pace with respiration. When applying a simple breath detecting algorithm, 88% of the breaths seen in a respiration air-flow reference could be detected correctly in PTT. Corresponding numbers for PEP and VTT were 76 and 81%, respectively. The performance during hypo- and hypertension was investigated by invoking blood pressure changes. In these situations, the error rates in breath detection were significantly higher. PTT can be derived from signals already present in most standard monitoring set-ups. The transit time technology thus has prospects to become an interesting alternative for respiration rate monitoring.

Reconnaître et traiter les intoxications oxycarbonées aiguës en 2005

Carbon monoxide (CO) poisoning is still complicated by a high mortality and morbidity rate. Diagnosis can be obvious but is most of time difficult and sometimes remained unknown. It is usually based on clinical signs and must be confirmed by assessment of CO level in room air or in patient's expired breathing or blood and detection of a source. Mild neurological sequel are very common. Normobaric oxygen is the first line treatment. Comatose and pregnant patients must undergo hyperbaric oxygen. All CO poisoning has to be declared to sanitary authority, which will in turn conduct a technical inspection to remove the source. The patient must be informed that he is at risk of new poisoning and of neurological complications. Progress in prevention and research in therapeutics are needed in order to reduce CO related morbidity.

Comparison of Nasal Pressure Transducer and Thermistor for Detection of Respiratory Events During Polysomnography in Children

The results of small studies have suggested that a nasal-cannula pressure transducer has a higher sensitivity than a thermistor in detecting hypopneas and diagnosing sleep-disordered breathing in both adults and children. We compared a thermistor alone, and in conjunction with a pressure transducer, for detection of sleep-disordered breathing in children during in-home polysomnography. Retrospective analysis of a subsample of a prospective cohort study. Students attending elementary school in the Tucson Unified School District. A subsample of the Tucson Children's Assessment of Sleep Apnea study population. Polysomnographic recordings of 40 children (24 girls and 16 boys, mean age 9.2 +/- 1.7 years; range 6-11 years) were analyzed to compare the detection of sleep-disordered breathing events by 2 different methods of measuring airflow: thermistor alone and thermistor with nasal-cannula pressure transducer (transducer) used simultaneously. The transducer detected all the respiratory events detected by the thermistor, but the thermistor detected only 84% of the transducer-defined events. Consequently, the transducer-derived mean respiratory disturbance index was higher than that detected by the thermistor (7.0 +/- 3.8 vs 5.9 +/- 3.4, P < .001). The bias error between transducer respiratory disturbance index and thermistor respiratory disturbance index on a Bland-Altman plot was 1.08 (95% confidence interval, 0.8 - 1.4). There was good agreement between the thermistor and the transducer for making the diagnosis of sleep apnea using a cutoff of a respiratory disturbance index greater than 5 (kappa = 0.69). The quality of the tracings with the transducer was comparable to that of the thermistor, but the transducer dislodged more frequently. The use of a nasal transducer in conjunction with a thermistor was more sensitive than the thermistor alone in detecting sleep-disordered breathing in children during unattended polysomnography.

Respiration can be monitored by photoplethysmography with high sensitivity and specificity regardless of anaesthesia and ventilatory mode

Photoplethysmography (PPG) is a non-invasive optical technique used, for instance, in pulse oximetry. Beside the pulse synchronous component, PPG has a respiratory synchronous variation (PPGr). Efforts have been made to utilize this component for indirect monitoring of respiratory rate and volume. Assessment of the clinical usefulness as well as of the physiological background of PPGr is required. We evaluated if anaesthesia and positive-pressure ventilation would affect PPGr. We recorded reflection mode PPGr, at the forearm, and the respiratory synchronous changes in central venous pressure (CVP), peripheral venous pressure (PVP) and arterial blood pressure (ABP) in 12 patients. Recordings for each patient were made on three occasions: awake with spontaneous breathing; anaesthetized with spontaneous breathing; and anaesthetized with positive-pressure ventilation. We analyzed the sensitivity, specificity, coherence and time relationship between the signals. PPGr sensitivity for breath detection was [mean (SD)] >86(21)% and specificity >96(12)%. Respiratory detection in the macrocirculation (CVP, PVP and ABP) showed a sensitivity >83(29)% and specificity >93(12)%. The coherence between signals was high (0.75-0.99). The three measurement situations did not significantly influence sensitivity, specificity or time shifts between the PPGr, PVP, ABP, and the reference CVP signal despite changes in physiological data between measurements. A respiratory synchronous variation in PPG and all invasive pressure signals was detected. The reflection mode PPGr signal seemed to be a constant phenomenon related to respiration regardless of whether or not the subject was awake, anaesthetized or ventilated, which increases its clinical usefulness in respiratory monitoring.

P43 Effectiveness of a mechanic‐chemical method in reducing malodor of dentures

Objective of investigation To assess effectiveness of a mechanic‐chemical denture cleansing to reduce malodor in denture wearers in comparison with a brushing only method.Methods Twenty‐nine denture wearers between 50 and 60 years old, 6 months after denture delivery were trained to clean their dentures with denture brush and soak in normal saline at nights for 1 month. The malodor of dentures was detected with a bad breath detector (VSC monitor: Tanita, Japan). In the following month the subjects were trained to clean with a denture brush but additionally soak in antiseptic mouthwash (Listerine, USA) each night and soak in 5% sodium hypochlorite twice a week for 5 min. At the end of 1 month the malodor of dentures was again assessed using the VSC monitor.Results and discussion For denture brush alone all cases showed severe malodor VSC levels. Following the mechanic‐chemical cleansing, 20 cases gave moderate and nine cases gave mild malodor VSC levels. Statistical analysis with Wilcoxon test determined the mechanic‐chemical method to have been significantly effective (P‐value &lt;0.05). The results show that for reducing malodor of dentures, denture brush alone is insufficient and use of antiseptic materials are necessary. Some studies have stated that allergic reactions to sodium hypochlorite are possible and in addition denture cleansing may be difficult for disabled or elderly patients. Therefore, future studies should focus on non‐allergic disinfectants and/or simpler/easier methods (recommended protocols) to carry out effective disinfection.Conclusion The mentioned mechanic‐chemical method proved to be effective at reducing malodor of dentures whilst brushing alone was insufficient.

呼吸検出に基づいたバスルーム用監視システムの開発

呼吸検出に基づいたバスルーム用監視システムの開発

An Algorithm for the Detection of Individual Breaths from the Pulse Oximeter Waveform

To determine if wavelet analysis techniques can be used to reliably identify individual breaths from the photoplethysmogram (PPG). Photoplethysmograms were obtained from 22 healthy adult volunteers timing their respiration rate in synchronisation with a metronome. A secondary timing signal was obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. Each PPG was analyzed using primary wavelet decomposition and two new, related, secondary decompositions to determine the accuracy of individual breath detection. The optimal breath capture was obtained by manually polling the three techniques, allowing detection of 466 out of the 472 breaths studied; a detection rate of 98.7% with no false positive breaths detected. Our technique allows the accurate capture of individual breaths from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.

Respiratory control by ventral surface chemoreceptor neurons in rats

A long-standing theory posits that central chemoreception, the CNS mechanism for CO(2) detection and regulation of breathing, involves neurons located at the ventral surface of the medulla oblongata (VMS). Using in vivo and in vitro electrophysiological recordings, we identify VMS neurons within the rat retrotrapezoid nucleus (RTN) that have characteristics befitting these elusive chemoreceptors. These glutamatergic neurons are vigorously activated by CO(2) in vivo, whereas serotonergic neurons are not. Their CO(2) sensitivity is unaffected by pharmacological blockade of the respiratory pattern generator and persists without carotid body input. RTN CO(2)-sensitive neurons have extensive dendrites along the VMS and they innervate key pontomedullary respiratory centers. In brainstem slices, a subset of RTN neurons with markedly similar morphology is robustly activated by acidification and CO(2). Their pH sensitivity is intrinsic and involves a background K(+) current. In short, the CO(2)-sensitive neurons of the RTN are good candidates for the long sought-after VMS chemoreceptors.

The Heart of Sleep

Heart failure is associated with high rates of hospitalization and mortality as well as great economic burden in the United States. Recent data show that a high percentage of patients with depressed left ventricular ejection fractions suffer from sleep-disordered breathing, contributing to this incidence of morbidity and mortality. Since the signs and symptoms associated with sleep disorders do not differ significantly from chronic heart failure signs and symptoms, detection and recognition of sleep-disordered breathing is a clinical challenge. Thus clinicians frequently fail to recognize it as a possible contributor to the development of heart failure or as a consequence of the disease. This article discusses sleep, sleep-disordered breathing, its effects and consequences on the cardiovascular system, strategies for identifying at-risk individuals, and treatment options.

117th ENMC Workshop: Ventilatory Support in Congenital Neuromuscular Disorders — Congenital Myopathies, Congenital Muscular Dystrophies, Congenital Myotonic Dystrophy and SMA (II) 4–6 April 2003, Naarden, The Netherlands

Eighteen participants from Australia, Austria, Denmark, Finland, France, Germany, The Netherlands, the UK, and the USA met in Naarden, representing a variety of disciplines with experience in the respiratory management of patients with neuromuscular disorders (NMD). The aims of the workshop were to agree upon and report minimum recommendations for the investigation and treatment of respiratory involvement in congenital muscular disorders, and to identify areas where further research is needed. The workshop specifically excluded patients with Duchenne muscular dystrophy where evidence for the need for and efficacy of the treatment of respiratory failure is better established. All participants contributed to the review and assessment of published evidence in the field, and current practice amongst the group was also compared. Despite the individual rarity of the conditions under consideration in this workshop, the accumulated experience of the group represented the care of more than 545 patients with these disorders, of whom around one-third were receiving mechanical ventilation.

A newly designed breath detector for halitosis

A newly designed breath detector for halitosis

Esophageal pressure monitoring in detection of sleep-disordered breathing.

The aim was to study the value of esophageal pressure monitoring combined with limited polygraphic recording (oxygen saturation, respiratory and leg movements, airflow, body position, and snoring sound) in diagnosis of sleep-disordered breathing. A prospective study of consecutive patients with snoring was carried out. Sixty-seven patients underwent an overnight study on ward. Patients with normal oxygen desaturation index and any periodic breathing disturbances combined with elevated esophageal pressure were further studied with complete polysomnography. The patient compliance with esophageal catheter was 87%. Esophageal pressure monitoring increased effectively the detection of sleep-disordered breathing with limited polygraphic recording. Sixty-seven percent of the patients with normal oxygen desaturation index and respiratory-related esophageal pressure variation had sleep-disordered breathing on complete polysomnography. Increased esophageal pressure variation was significantly related with oxygen desaturation index and obstructive sleep apnea diagnosis (P <.001). All together, 48% of the mainly nonobese snorers had objective findings of sleep-disordered breathing. Patients with upper airway resistance syndrome were few. Fifteen percent of the patients had periodic leg movements. Neither subjective or objective sleepiness nor snoring or obesity adequately exposed sleep-disordered breathing in this material. Esophageal pressure monitoring increases markedly the diagnostic value of limited polygraphic recording as a screening study for sleep-disordered breathing.

Detection of bronchial breathing caused by pneumonia.

The classic auscultation with stethoscope is the established clinical method for the detection of lung diseases. The interpretation of the sounds depends on the experience of the investigating physician. Therefore, a new computer-based method has been developed to classify breath sounds from digital lung sound recordings. Lung sounds of 11 patients with one-sided pneumonia and bronchial breathing were recorded on both the pneumonia side and on contralateral healthy side simultaneously using two microphones. The spectral power for the 300-600 Hz frequency band was computed for four respiratory cycles and normalized. For each breath, the ratio R between the time-segments (duration = 0.1 s) with the highest inspiratory and highest expiratory flow was calculated and averaged. We found significant differences in R between the pneumonia side (R = 1.4 +/- 1.3) and the healthy side (R = 0.5 +/- 0.5; p = 0.003 Wilcoxon-test) of lung. In 218 healthy volunteers we found R = 0.3 +/- 0.2 as a reference-value. The differences of ratio R (delta R) between the pneumonia side and the healthy side (delta R = 1.0 +/- 0.9) were significantly higher compared to follow-up studies after recovery (delta R = 0.0 +/- 0.1, p = 0.005 Wilcoxon-test). The computer based detection of bronchial breathing can be considered useful as part of a quantitative monitoring of patients at risk to develop pneumonia.

In vitro assessment of equipment and software to assess tidal breathing parameters in infants.

The aim of this in vitro study was to compare the measurement accuracy of two currently available devices for measuring tidal breathing in infants. A mechanical model pump was used to generate flow profiles which simulated those observed in infants. A range of flows was applied simultaneously to two different devices, namely the commercially available SensorMedics 2600 (SM 2600) and more recently developed, custom-made equipment based on the flow-through technique (FTT). Automatically derived values from both devices were compared with one another and with manual calculations of printouts of the same breaths. There were no differences in the raw flow signal obtained from the two devices, nor between values calculated automatically or manually from the FTT. Similarly, the deviations between the FTT and SM 2600 were <3% for tidal volume, respiratory frequency and minute ventilation. However, when comparing either with manually calculated values or those derived automatically from the FTT, there was a systematic and highly significant underestimation of shape-dependent parameters, such as the time to peak tidal expiratory flow as a proportion of tidal expiratory time (tPTEF/tE), derived by the SM 2600. The lower the applied flow, the higher the observed deviations, the underestimation being up to 60% when flows simulating those observed in preterm neonates were applied. These errors appear to result from differences in signal processing such as the algorithms used for breath detection and can only be detected if appropriate nonsinusoidal flow profiles representing those seen in infants are used to evaluate equipment.

Diagnosis of diabetes by image detection of breath using gas-sensitive laps

Gaseous respiratory acetone detection using LAPS (Light Addressable Potentiometric Sensors) is proposed as a supplementary method for the diagnosis of diabetes. First, electric simulation of the LAPS systern is studied to obtain the optimum sensitivity of tested odours. Gas phase chromatography is used to obtain correlations between blood sugar levels and acetone from the breath. Then several experiments are carried out to obtain the 2-dimension static and dynamic images of respiratory acetone and air. All experimental results show that the LAPS can be very useful for the detection of respiratory odours, especially the diagnosis of diabetes.

Closed-loop stimulation of hypoglossal nerve in a dog model of upper airway obstruction.

Electrical stimulation of upper airway (UAW) muscles has been under investigation as a treatment method for obstructive sleep apnea (OSA). Particular attention has been given to the electrical activation of the genioglossal muscle, either directly or via the stimulation of the hypoglossal nerve (HG), since the genioglossus is the main tongue protrusor muscle. Regardless of the stimulation site or method, an implantable electrical stimulation device for OSA patients will require a reliable method for detection of obstructive breaths to apply the stimulation when needed. In this paper, we test the hypothesis that the activity of the HG nerve can be used as a feedback signal for closed-loop stimulation of the HG nerve in an animal model of UAW obstruction where a force is applied on the submental region to physically narrow the airways. As an advantage, the method uses a single electrode for both recording and stimulation of the HG nerve. Simple linear filtering techniques were found to be adequate for producing the trigger signal for the electrical stimulation from the HG recordings. Esophageal pressure, which was used to estimate the size of the UAW passage, returned to the preloading values during closed-loop stimulation of the HG nerve. The data demonstrate the feasibility of the closed-loop stimulation of the HG nerve using its activity as the feedback signal.