Subjects Breathing Research Articles

Early medical therapy for acute laryngeal injury (ALgI) following endotracheal intubation: a protocol for a prospective single-centre randomised controlled trial

IntroductionRespiratory failure requiring endotracheal intubation accounts for a significant proportion of intensive care unit (ICU) admissions. Little attention has been paid to the laryngeal consequences of endotracheal intubation. Acute laryngeal...

GEP-based predictive modeling of breathing resistances of wearing respirators on human body via sEMG and RSP sensors

PurposeBreathing resistance is the main factor that influences the wearing comfort of respirators. This paper aims to demonstrate the feasibility of using the gene expression programming (GEP) for the purpose of predicting subjective perceptions of breathing resistances of wearing respirators via surface electromyography (sEMG) and respiratory signals (RSP) sensors.Design/methodology/approachThe authors developed a physiological signal monitoring system with a specific garment. The inputs included seven physical measures extracted from (RSP) and (sEMG) signals. The output was the subjective index of breathing resistances of wearing respirators derived from the category partitioning-100 scale with proven levels of reliability and validity. The prediction model was developed and validated using data collected from 30 subjects and 24 test combinations (12 respirator conditions × 2 motion conditions). The subjects evaluated 24 conditions of breathing resistances in repeated measures fashion.FindingsThe results show that the GEP model can provide good prediction performance (R2 = 0.71, RMSE = 0.11). This study demonstrates that subjective perceptions of breathing resistance of wearing respirators on the human body can be predicted using the GEP via sEMG and RSP in real-time, at little cost, non-invasively and automatically.Originality/valueThis is the first paper suggesting that subjective perceptions of subjective breathing resistances can be predicted from sEMG and RSP sensors using a GEP model, which will remain helpful to the scientific community to start further human-centered research work and product development using wearable biosensors and evolutionary algorithms.

Real-time heart rate variability analysis as a means of hypercapnia detection

We hypothesized that heart rate variability (HRV) can be used as a physiological monitor of exposures to hypercapnia. HRV was analyzed in 15 male subjects breathing air and then air plus 4%, 5% or 6% carbon dioxide (CO2). A progressive elevation in randomness of HRV best depicted as a divergence of data on Poincar é plots of self-similarity occurred as CO2 increased, and resolved when returning sd to ambient conditions. Results indicate that HRV may be useful as a prompt (⟨ 2 minute) early warning of hypercapnia that occurs prior to overt symptomatology.

Use of accelerometers for automatic regional chest movement recognition during tidal breathing in healthy subjects

Recognition of breathing patterns helps clinicians to understand acute and chronic adaptations during exercise and pathological conditions. Wearable technologies combined with a proper data analysis provide a low cost option to monitor chest and abdominal wall movements. Here we set out to determine the feasibility of using accelerometry and machine learning to detect chest-abdominal wall movement patterns during tidal breathing. Furthermore, we determined the accelerometer positions included in the clusters, considering principal component domains. Eleven healthy participants (age: 21 ± 0.2 y, BMI: 23.4 ± 0.7 kg/m2, FEV1: 4.1 ± 0.3 L, VO2: 4.6 ± 0.2 mL/min kg) were included in this cross-sectional study. Spirometry and ergospirometry assessments were performed with participants seated with 13 accelerometers placed over the thorax. Data collection lasted 10 min. Following signal pre-processing, principal components and clustering analyses were performed. The Euclidean distances in respect to centroids were compared between the clusters (p < 0.05), identifying two clusters (p < 0.001). The first cluster included sensors located at the right and left second rib midline, body of sternum, left fourth rib midline, right and left second thoracic vertebra midline, and fifth thoracic vertebra. The second cluster included sensors at the fourth right rib midline, right and left seventh ribs, abdomen at linea alba, and right and left tenth thoracic vertebra midline. Costal-superior and costal-abdominal patterns were also recognized. We conclude that accelerometers placed on the chest and abdominal wall permit the identification of two clusters of movements regarding respiration biomechanics.

Objective and Subjective Effects of a Prototype Nasal Dilator Strip on Sleep in Subjects with Chronic Nocturnal Nasal Congestion.

IntroductionThis exploratory study characterized the performance of a nasal dilator strip with improved spring forces in lowering nasal resistance during sleep and reducing sleep-disordered breathing in subjects with difficulty sleeping due to chronic nocturnal nasal congestion.MethodsSubjects applied the strip at bedtime for 28 days (active phase; n = 70). Objective assessments included snoring variables, breathing route during sleep, and polysomnography measures compared with baseline. Nasal breathing, congestion, and sleep were measured subjectively using rating scales and questionnaires. During a crossover nasal resistance phase (n = 55), nasal resistance was measured using posterior rhinomanometry with the strip applied on one of two nights.ResultsIn the active phase, breathing and sleep were perceived to improve, with less daytime sleepiness (P < 0.04) and increased ease of breathing, sleep quality, staying asleep, and feeling refreshed in the morning (all P < 0.0001). However, while objective polysomnography metrics were generally similar with and without the strip, median wake after sleep onset time was numerically reduced by ~ 11 min, and the spontaneous arousal rate fell by ~ 37%. In the nasal resistance phase (n = 55), median resistance (at 0.2–0.25 l/s) while asleep was 39.1% lower with (n = 37) versus without (n = 36) the strip (1.34 vs. 2.20 cmH2O/l/s; P = 0.048).ConclusionsThis exploratory study supports a role for the improved spring force nasal dilator strip in alleviating sleep-related symptoms in subjects with chronic nasal congestion, potentially via lowering nasal resistance and reducing nocturnal awakenings. A larger study is indicated to confirm these preliminary data.ClinicalTrials.gov identifierNCT03105297.FundingGlaxoSmithKline Consumer Healthcare.Plain Language SummaryPlain language summary available for this article.Electronic supplementary materialThe online version of this article (10.1007/s12325-019-00980-z) contains supplementary material, which is available to authorized users.

Assessment of Pulmonary Function After Osteopathic Manipulative Treatment vs Standard Pulmonary Rehabilitation in a Healthy Population.

Standard pulmonary rehabilitation (SPR) does not use osteopathic manipulative treatment (OMT), but OMT has potential to improve lung function and patient perception of breathing. To analyze the immediate effects of OMT and SPR techniques on pulmonary function using spirometry and subjective ratings in young, healthy persons. Participants were healthy students recruited from the Lake Erie College of Osteopathic Medicine-Bradenton and were randomly assigned to either the OMT or SPR group. During the first 4 weeks, each participant in the OMT group received 1 OMT technique (rib raising, doming of the diaphragm, thoracic lymphatic pump, and thoracic high velocity, low amplitude), and each participant in the SPR group received 1 SPR treatment (tapotement, pursed lip breathing, saline nebulizer, and rest) per week. Treatments were then ranked based on positive change in pulmonary function as measured by forced expiratory volume in the first second of expiration (FEV1) and forced vital capacity (FVC). During the fifth week, the OMT group received the 2 highest-ranked OMT techniques, and the SPR group received the 2 highest-ranked SPR treatments. During the sixth week, the OMT group received the highest-ranked OMT and SPR treatment, while the SPR group received the same treatment combination but in the reverse order. Pulmonary function, as measured through FEV1, FVC, and FEV1/FVC, were collected before and after each treatment or treatment combination. Participants subjectively rated change in breathing after each treatment. A total of 53 students participated in the study, with 28 in the OMT group and 25 in the SPR group. In the OMT group, rib raising yielded the highest positive mean (SD) change of 0.001 (0.136) L in FEV1 and 0.052 (0.183) L in FVC, followed by lymphatic pump, with a change of 0.080 (0.169) L in FEV1 and -0.031 (0.229) L in FVC. In the SPR group, pursed lip breathing yielded the highest positive mean (SD) change of 0.101 (0.278) L in FEV1 and 0.031 (0.179) L in FVC, followed by tapotement, with a change of 0.045 (0.229) L in FEV1 and 0.061 (0.239) L in FVC. Saline treatment significantly decreased lung function. All other treatments did not result in any significant changes in lung function. Overall, SPR subjective ratings were significantly lower than ratings for both OMT and combination (OMT+SPR) treatments. Saline significantly reduced lung function and had low subjective posttreatment ratings in young healthy adults. Additionally, OMT and combination OMT and SPR significantly improved subjective breathing more than SPR alone. Future applications of this study include evaluating OMT and SPR effects on lung function in patients with various pulmonary conditions.

Особенности нарушений носового дыхания у пациентов с назальной обструкцией

The objective of the study is to examine the specific features of the aerodynamic processes in the nasal cavity of patients with subjective nasal obstruction, and to make a differentiated analysis of the causes of its formation. Materials and methods: the authors examined 72 patients aged 18 to 64 years with subjective complaints of nasal breathing obstructions. Of these, 36 patients had not previously undergone surgical correction of external nose and intra-nasal structures. The other 36 patients have undergone septoplasty, rhinoplasty, turbinotomy or inferior nasal concha vasotomy over the period of 2.7±0.6 years. All subjects were surveyed, nasal obstruction was assessed using VAS scale, otorhinolaryngological examination and anterior active rhinomanometry with calculation of nasal resistance and volumetric nasal flow and acoustic rhinometry with the measurement of MCA 1 before and after α2-adrenomimetic test was performed. Results: in the patients with subjective nasal breathing obstructions, who had not previously undergone surgical correction of the external nose and intra-nasal structures, the most frequently identified causes of nasal obstruction are functional (38.9%) and structural (38.9%). The combined structural and functional changes in airflow circulation were found in 22.2% (8 patients). According to the modified VAS scale, 12 patients (32.6%) in this group had an underestimation of subjective degree of nasal obstruction, compared with objectively recorded aerodynamic respiratory function parameters. Among patients who had previously undergone surgical correction of intra-nasal structures, according to objective assessment of aerodynamic parameters, 11.1% have no nasal breathing disorders, in 47.2% of patients, the main cause of nasal obstruction is the nasal mucosa reactive edema, and 36.1% of patients have unsatisfactory functional results of surgical treatment due to incomplete correction of structural disorders. Conclusion: the anterior active rhinomanometry in combination with acoustic rhinometry should be conducted if the patients have subjective nasal breathing obstructions both at the stage of planning the surgical correction of intra-nasal structures and in the remote postoperative period for differentiated analysis of the nasal obstruction causes and provision of optimal functional result.

Intermodulation-Based Nonlinear Smart Health Sensing of Human Vital Signs and Location

This paper discusses the use of a nonlinear sensing technology based on radio frequency (RF) intermodulation response to track both the vital signs and location of human subjects. Smart health sensing was realized through the use of a wearable nonlinear tag and an intermodulation-based nonlinear sensor operating in both Doppler and frequency shift keying (FSK) modes. The Doppler mode was used to detect the heartbeat and breathing of the target subject while human subject localization was achieved in the FSK mode. One of the key advantages of this nonlinear smart sensor system was clutter rejection. This system identified the signal reflected from the wearable nonlinear tag and suppressed undesired signals and interferences that were reflected from other objects. The wearable tags used for the experiments were passive, hence they did not require any battery or power supply for their operation. Since the respiration signal is typically stronger than the heartbeat signal, the nonlinear detection setup was designed such that the respiratory signal receives less gain to avoid its sidelobes and harmonics from interfering heartbeat signal detection. This enhanced the heartbeat signal quality so that the cardiac activity could be easily tracked. Four types of experiments were performed on multiple subjects to demonstrate the advantages of this intermodulation-based nonlinear smart health sensing system. Previously, 2nd order harmonics were utilized for target localization and vital sign monitoring. However, these 2nd order harmonics suffer from high path loss and licensing issues. In this paper, target localization and smart health sensing were realized using 3rd order intermodulation with less path loss and no licensing issues compared with its harmonic counterparts. The experiment performed in nonlinear FSK mode was able to detect and locate the source of motion with high accuracy. Similarly, vital signs were recorded in the nonlinear Doppler mode. The design effectively made the amplitude of the heartbeat signal component more prominent, so that the sidelobes and harmonics of respiration do not suppress heartbeat signal.

Intercostal muscle oxygenation during expiratory load breathing at rest

BackgroundDuring acute bronchial obstruction, despite a higher work of breathing, blood supply and oxygen availability may be reduced in intercostal muscles because of mechanical constraints. This hypothesis was assessed in healthy subjects breathing with and without expiratory load (ETL). MethodsEleven men (24 ± 2 years) breathed at rest for 5 min in unloaded condition and for 20 min through a 20-cmH2O ETL. Tissue saturation index (TSI) and changes (Δ) in concentration of total and oxy-haemoglobin ([tHb] and [O2Hb]) were measured in the seventh intercostal space by near-infrared spectroscopy. Results[tHb] and [O2Hb] decreased with ETL (-5.16 μM and -3.54 μM; p < 0.05). TSI did not vary. Negative correlations were observed between Δ[O2Hb] and changes in expiratory flow rate (ΔVt/Te) and between ΔTSI and Δ V˙E (r = -0.78 and -0.74; p ≤ 0.01). ConclusionDespite decreases in Hb concentrations, saturation in oxygen was not reduced with ETL in intercostal muscles, suggesting a satisfactory ventilatory and/or hemodynamic arrangement.

Validity and reliability of rating scales for subjective breathing resistance of wearing respirators

Purpose Investigating the subjective breathing resistance of wearing respirators requires a valid and reliable technique to measure breathing resistance. The purpose of this study is to test the validity and reliability of several rating scales and select the best for investigation of breathing resistance. Design/methodology/approach The authors designed three scales, that is, BRX scale, CP-100 scale and RVAS scale, and 30 subjects were separated into three groups, each group with a different scale. They sat for 5 min and walked for 5 min while wearing three models of respirators. After each trial, subjects were asked to complete subjective ratings of breathing resistance. Reliability was examined by the coefficient of Cronbach’s α, and validity was examined through content validity, discriminant validity and criterion validity. Generally, subjects were capable of reporting their sensation of breathing resistance by using the rating scale technique. However, the accuracy of rating strongly depended upon the properties of the scale. Findings The CP-100 scale was found to be highly reliable and most valid for rating subjective breath resistance. The validated CP-100 scale is very sensitive and accurate. Originality/value This is the first paper to select the best subjective scale for investigation of breathing resistance of respirators. The CP-100 scale will find wide applications in subjective breathing resistance evaluation for the use of respirators in industrial benchmarking activities. It will introduce the human factor engineering into the respirator manufacturing to improve the comfort of respirators.

Investigating the ability of non-invasive measures of cardiac output to detect a reduction in blood volume resulting from venesection in spontaneously breathing subjects

BackgroundMonitoring cardiac output (CO) in shocked patients provides key etiological information and can be used to guide fluid resuscitation to improve patient outcomes. Previously this relied on invasive monitoring, restricting its use in the Emergency Department (ED) setting. The development of non-invasive devices (such as LiDCOrapidv2 with CNAP™ and USCOM 1A), and ultrasound based measurements (Transthoracic echocardiography, inferior vena cava collapsibility index (IVCCI), carotid artery blood flow (CABF) and carotid artery corrected flow time (FTc)) enables stroke volume (SV) and CO to be measured non-invasively in the ED. We investigated the ability of these techniques to detect a change in CO resulting from a 500 ml reduction in circulating blood volume (CBV) following venesection in spontaneously breathing subjects. Additionally, we investigated if using incentive spirometry to standardise inspiratory effort improved the accuracy of IVC based measurements in spontaneously breathing subjects.MethodsWe recorded blood pressure, heart rate, IVCCI, CABF, FTc, transthoracic echocardiographic (TTE) SV and CO, USCOM 1A SV and CO, LIDCOrapidv2 SV, CO, Stroke volume variation (SVV) and pulse pressure variation (PPV) in 40 subjects immediately before and after venesection. The Log-Odds and coefficient of variation of the difference between pre- and post-venesection values for each technique were used to compare their ability to consistently detect CO changes resulting from a reduction in CBV resulting from venesection.ResultsTTE consistently detected a reduction in CO associated with venesection with an average decrease in measured CO of 0.86 L/min (95% CI 0.61 to 1.12) across subjects. None of the other investigated techniques changed in a consistent manner following venesection. The use of incentive spirometry improved the consistency with which IVC ultrasound was able to detect a reduction in CBV.ConclusionsIn a population of spontaneously breathing patients, TTE is able to consistency detect a reduction in CO associated with venesection.

Use of real-time ultrasound imaging for biofeedback of diaphragm motion during normal breathing in healthy subjects

Objective: To determine if the provision of visual biofeedback using real-time rehabilitative ultrasound imaging (RUSI) enhances the acquisition and retention of diaphragm muscle recruitment during exercise. Design: Two group pretest posttest design. Methods: Thirty healthy subjects were randomly assigned to the verbal feedback group (VG, n=15) or the visual and verbal feedback group (VVG, n=15). The VG performed breathing exercises 10 times with verbal feedback, and the VVG also performed breathing exercises 10 times with verbal feedback and visual feedback with the use of RUSI to measure changes in diaphragm thickness (DT). For DT, the mid-axillary lines between ribs 8 and 9 on both sides were measured in standing, and then the chest wall was perpendicularly illuminated using a linear transducer with the patients in supine to observe the region between rib 8 and 9 and to obtain 2-dimensional images. DT was measured as the distance between the two parallel lines that appeared bright in the middle of the pleura and the peritoneum. After one week, three repetitions (follow-up session) were performed to confirm retention effects. Intra- and between- group percent changes in diaphragm muscle thickness were assessed. Results: In the VVG, the intervention value had a medium effect size compared to the baseline value, but the follow-up value decreased to a small effect size. In the between-group comparisons, during the intervention session, the VVG showed no significant effect on percent change of DT but had a medium effect size compared to the VG (p=0.050, Cohen’s d=0.764). During the follow- up session, retention effect did not persist (p=0.311, Cohen’s d=0.381). Conclusions: RUSI can be used to provide visual biofeedback and improve performance and retention in the ability to activate the diaphragm muscle in healthy subjects. Future research needs to establish a protocol for respiratory intervention to maintain the effect of diaphragmatic breathing training using RUSI with visual feedback.

Combined high-speed holographic shape and full-field displacement measurements of tympanic membrane.

The conical shape of the tympanic membrane (TM or eardrum) plays an important role in its function, such that variations in shape alter the acoustically induced motions of the TM. We present a method that precisely determines both shape and acoustically induced transient response of the entire TM using the same optics and maintaining the same coordinate system, where the TM transient displacements due to a broadband acoustic click excitation (50-μs impulse) and the shape are consecutively measured within <200 ms. Interferograms gathered with continuous high-speed (>2 kHz) optical phase sampling during a single 100-ms wavelength tuning ramp allow precise and rapid reconstructions of the TM shape at varied resolutions (50 to 200 μm). This rapid acquisition of full-field displacements and shape is immune to slow disturbances introduced by breathing or heartbeat of live subjects. Knowledge of TM shape and displacements enables the estimation of surface normal displacements regardless of the orientation of the TM within the measurement system. The proposed method helps better define TM mechanics and provides TM structure and function information useful for the diagnosis of ear disease.

Heart-Lung interaction in spontaneous breathing subjects: the basics

Heart-lung interactions occur primarily because of two components of lung inflation, changes in pleural pressure and changes in transpulmonary pressure. Of these, changes in pleural pressure dominate during spontaneous breathing. Because the heart is surrounded by pleural pressure, during inspiration the environment of the heart falls relative to the rest of the body. This alters inflow into the right heart and outflow from the left heart. Alterations in transpulmonary pressure can alter the outflow from the right heart and the inflow to the left heart. These interactions are modified by the cardiac and respiratory frequency, ventricular function and magnitude of the respiratory efforts.

Effects of Diaphragmatic Breathing With and Without Pursed-Lips Breathing in Subjects With COPD

Breathing exercises, such as diaphragmatic breathing and pursed-lips breathing, play a role in some individuals with COPD and might be considered for those patients who are unable to exercise. However, in the literature are reports of some adverse effects of diaphragmatic breathing in patients with COPD. Thus, the purpose of this study was to assess the effects of diaphragmatic breathing and diaphragmatic breathing combined with pursed-lips on chest wall kinematics, breathlessness, and chest wall asynchrony in subjects with COPD, and also to assess whether the combination of both exercises reduces the adverse effects of diaphragmatic breathing while maintaining its benefits. Seventeen subjects with COPD, mean ± SD, 65 ± 7 y of age, with a history of smoking and clinical stability without hospitalization or symptoms of exacerbation in the past 4 wk, were evaluated. On day 1, participants' characteristics were collected, and they learned diaphragmatic breathing and its combination with pursed-lips breathing. On day 2, the participants were evaluated by optoelectronic plethysmography with the participants in the seated position while performing breathing exercises. Diaphragmatic breathing and diaphragmatic breathing plus pursed-lips breathing promoted a significant increase in chest wall tidal volume and its compartments as well as a reduction in breathing frequency compared with quiet breathing. No significant changes were observed in dyspnea or end-expiratory volume of the chest wall. A significant increase in asynchrony (inspiratory-expiratory phase ratio) was observed during diaphragmatic breathing and diaphragmatic breathing plus pursed-lips breathing compared with quiet breathing, with no differences observed between the exercises. Despite the increase in asynchrony, both breathing exercises were able to improve chest wall volumes without affecting dyspnea. The combination of exercises maintained the benefits but did not reduce the adverse effects of diaphragmatic breathing.

Quantitative analysis in nonlinear complexity detection of meditative heartbeats

Meditation, a self-regulation practice, attracts attention on its physiological and psychological effects, and its effects on nonlinear complexity of heartbeats are analyzed in our contribution. Heartbeats of Chinese Chi, Kundalini Yoga practitioners and non-meditation metronomic breathing subjects, all from physionet, contribute to our research. We introduce the meditative heart rates in time and frequency domains, and extract their nonlinear dynamics by local dynamic and global static symbolic time-series analysis. Shannon entropy for each individual symbolization and joint entropy for the two kinds of symbolic transformations are applied to detect heartbeats’ nonlinear complexity. Test results prove that symbolic entropy is an exquisite quantitative analysis to characterize and distinguish nonlinear complexity of the physiological signals. Heart rates, during meditation, show highest regularities and lowest nonlinear complexities, and meditators, even in pre-meditation status, have lower heartbeats nonlinear complexity than the non-meditation volunteers, which suggest that meditation enhances cardiac self-regulation and reduces the nonlinear dynamic complexity of heart rates.

Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to non-invasively assess some features of the respiratory function in humans as well as in laboratory animals. The present article focuses on the application of the double-chamber plethysmography (DCP) in small animals. It provides background information on the methodology as well as a detailed step-by-step procedure to successfully assess respiratory function in conscious, spontaneously breathing animals in a non-invasive manner. The DCP can be used to monitor the respiratory function of multiple animals in parallel, as well as to identify changes induced by aerosolized substances over a chosen time period and in a repeated manner. Experiments on control and allergic mice are used herein to demonstrate the utility of the technique, explain the associated outcome parameters, as well as to discuss the related advantages and shortcomings. Overall, the DCP provides valid and theoretically sound readouts that can be trusted to evaluate the respiratory function of conscious small animals both at baseline and after challenges with aerosolized substances.

Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography.

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to non-invasively assess some features of the respiratory function in humans as well as in laboratory animals. The present article focuses on the application of the double-chamber plethysmography (DCP) in small animals. It provides background information on the methodology as well as a detailed step-by-step procedure to successfully assess respiratory function in conscious, spontaneously breathing animals in a non-invasive manner. The DCP can be used to monitor the respiratory function of multiple animals in parallel, as well as to identify changes induced by aerosolized substances over a chosen time period and in a repeated manner. Experiments on control and allergic mice are used herein to demonstrate the utility of the technique, explain the associated outcome parameters, as well as to discuss the related advantages and shortcomings. Overall, the DCP provides valid and theoretically sound readouts that can be trusted to evaluate the respiratory function of conscious small animals both at baseline and after challenges with aerosolized substances.

Pancreatic ductal adenocarcinoma can be detected by analysis of volatile organic compounds (VOCs) in alveolar air

BackgroundIn the last decade many studies showed that the exhaled breath of subjects suffering from several pathological conditions has a peculiar volatile organic compound (VOC) profile. The objective of the present work was to analyse the VOCs in alveolar air to build a diagnostic tool able to identify the presence of pancreatic ductal adenocarcinoma in patients with histologically confirmed disease.MethodsThe concentration of 92 compounds was measured in the end-tidal breath of 65 cases and 102 controls. VOCs were measured with an ion-molecule reaction mass spectrometry. To distinguish between subjects with pancreatic adenocarcinomas and controls, an iterated Least Absolute Shrinkage and Selection Operator multivariate Logistic Regression model was elaborated.ResultsThe final predictive model, based on 10 VOCs, significantly and independently associated with the outcome had a sensitivity and specificity of 100 and 84% respectively, and an area under the ROC curve of 0.99. For further validation, the model was run on 50 other subjects: 24 cases and 26 controls; 23 patients with histological diagnosis of pancreatic adenocarcinomas and 25 controls were correctly identified by the model.ConclusionsPancreatic cancer is able to alter the concentration of some molecules in the blood and hence of VOCs in the alveolar air in equilibrium. The detection and statistical rendering of alveolar VOC composition can be useful for the clinical diagnostic approach of pancreatic neoplasms with excellent sensitivity and specificity.

Upper airway dynamic imaging during tidal breathing in awake and asleep subjects with obstructive sleep apnea and healthy controls.

We used magnetic resonance imaging (MRI) to quantify change in upper airway dimension during tidal breathing in subjects with obstructive sleep apnea (OSA, N = 7) and BMI‐matched healthy controls (N = 7) during both wakefulness and natural sleep. Dynamic MR images of the upper airway were obtained on a 1.5 T MR scanner in contiguous 7.5 mm‐thick axial slices from the hard palate to the epiglottis along with synchronous MRI‐compatible electroencephalogram and nasal/oral flow measurements. The physiologic data were retrospectively scored to identify sleep state, and synchronized with dynamic MR images. For each image, the upper airway was characterized by its area, and linear dimensions (lateral and anterior–posterior). The dynamic behavior of the upper airway was assessed by the maximum change in these parameters over the tidal breath. Mean upper airway caliber was obtained by averaging data over the tidal breath. There was no major difference in the upper airway structure between OSA and controls except for a narrower airway at the low‐retropalatal/high‐retroglossal level in OSA than in controls. Changes in upper airway size over the tidal breath ((maximum − minimum)/mean) were significantly larger in the OSA than in the control group in the low retropalatal/high retroglossal region during both wakefulness and sleep. In the four OSA subjects who experienced obstructive apneas during MR imaging, the site of airway collapse during sleep corresponded to the region of the upper airway where changes in caliber during awake tidal breathing were the greatest. These observations suggest a potential role for dynamic OSA imaging during wakefulness.