Breathing Research Articles

Instant Disinfecting Face Masks Utilizing Electroporation Powered by Respiration‐Driven Triboelectric Nanogenerators

AbstractWearing face masks is an effective non‐pharmaceutical strategy to inhibit the transmission of airborne diseases. Nonetheless, most commercial face masks lack disinfecting capabilities, posing risks of secondary transmission, while those with antimicrobial coatings are incapable of instant pathogen inactivation. Herein, a proof‐of‐concept instant disinfecting face mask is demonstrated consisting of a Cu(OH)2‐nanowire electroporation filter powered by a respiration‐driven triboelectric nanogenerator (R‐TENG). The R‐TENG comprises electrospun polyvinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) membranes. A dome‐shaped PVA membrane is specifically designed to maximize the effective contact area. Coupling the novel dome‐shape design with maximized β‐phase crystallites of PVDF, the enhanced R‐TENG generates an open‐circuit voltage of 120 V under the normal breathing rate of an adult, resulting in an amplified electric field of 19 MV m−1 at the nanowire tips of the electroporation filter. Under this high localized electric field, effective inactivation of bacteria (>99.9%) is achieved via a synergy of electroporation and physical penetration. Conversely, when the R‐TENG is disconnected, only partial inactivation (90%–99%) via physical penetration is realized. For the first time, it shows that R‐TENG powered electroporation is a viable solution to achieve instant, effective disinfection, paving the way for next‐generation face masks.

(Invited) Triboelectric Nanogenerators for Self-Powered Sensing and Human-Machine-Interfaces

Wearable and portable electronics are garnering substantial interest for applications ranging from personalized healthcare monitoring to implantable devices and prosthetics. The demand for long-term operation poses significant challenges to their power supply. To address this, the development of novel self-powered systems holds considerable promise. In this talk, I will discuss our recent advancements in crafting triboelectric nanogenerators (TENGs) for self-powered sensing and human-machine interfaces (HMIs). I will first introduce our multifunctional tactile sensors inspired by human skin. These sensors combine a triboelectric nanogenerator layer with a piezoresistive sensing layer, emulating the ability of human skin to detect a variety of static and dynamic stimuli. This sensor can successfully recognize voice patterns, monitor physiological signals, and track human motion in real-time. Then, I will unveil our self-powered smart packaging system, which is driven by a novel desiccant-based triboelectric nanogenerator (D-TENG). This system offers a viable method for continuous monitoring of product conditions and quality control throughout the supply chain, thus minimizing food waste and maintaining a comprehensive log of logistics, especially critical in vaccine transport. Lastly, I will present our novel breath-driven triboelectric sensor in respiratory monitoring. This sensor can precisely detect breath variations and convert different breathing patterns into electrical signals, all without impeding normal breathing. It enables severely disabled individuals to control household appliances through a breath-driven HMI and provides an intelligent monitoring system for emergency situations. This innovative work paves the way for future development in self-powered sensors and advanced HMIs, enhancing assistive technology for individuals with disabilities.

SCG variability and spectral energy distribution during normal breathing and breath hold at different lung volumes and airway pressures

Seismocardiographic (SCG) signals are chest wall vibrations induced by cardiac activity and are potentially useful for cardiac monitoring and diagnosis. SCG waveform is observed to vary with respiration, but the mechanism of these changes is poorly understood as alterations in autonomic tone, lung volume, heart location and intrathoracic pressure are all varying during the respiratory cycle. Understanding SCG variability and its sources may help reduce variability and increase SCG clinical utility. This study investigated SCG variability during breath holding (BH) at two different lung volumes (i.e., end inspiration and end expiration) and five airway pressures (i.e., 0, ± 2–4, and ± 15–20 cm H2O). Variability during normal breathing was also studied with and without grouping SCG beats into two clusters of similar waveform morphologies (performed using the K-medoid algorithm in an unsupervised machine learning fashion). The study included 15 healthy subjects (11 Females and 4 males, Age: 21 ± 2 y) where SCG, ECG, and spirometry were simultaneously acquired. SCG waveform variability was calculated at each experimental state (i.e., lung volume and airway pressure). Results showed that breath holding was more effective in reducing the intra-state variability of SCG than clustering normal breathing data. For the BH states, the intra-state variability increased as the airway pressure deviated from zero. The subaudible-to-audible energy ratio of the BH states increased as the airway pressure decreased below zero which may be related to the effect of the intrathoracic pressure on cardiac afterload and blood ejection. When combining the BH waveforms at end inspiration and end expiration states (at the same airway pressures) into one group, the intra-state variability increased, which suggests that the lung volume and associated change in heart location were a significant source of variability. The linear trend between airway pressure and waveform changes was found to be statistically significant for BH at end expiration. To confirm these findings, more studies are needed with a larger number of airway pressure levels and larger number of subjects.

Distortionless, free-breathing, and respiratory resolved 3D diffusion weighted imaging of the abdomen.

Abdominal imaging is frequently performed with breath holds or respiratory triggering to reduce the effects of respiratory motion. Diffusion weighted sequences provide a useful clinical contrast but have prolonged scan times due to low signal-to-noise ratio (SNR), and cannot be completed in a single breath hold. Echo-planar imaging (EPI) is the most commonly used trajectory for diffusion weighted imaging but it is susceptible to off-resonance artifacts. A respiratory resolved, three-dimensional (3D) diffusion prepared sequence that obtains distortionless diffusion weighted images during free-breathing is presented. Techniques to address the myriad of challenges including: 3D shot-to-shot phase correction, respiratory binning, diffusion encoding during free-breathing, and robustness to off-resonance are described. A twice-refocused, M1-nulled diffusion preparation was combined with an RF-spoiled gradient echo readout and respiratory resolved reconstruction to obtain free-breathing diffusion weighted images in the abdomen. Cartesian sampling permits a sampling density that enables 3D shot-to-shot phase navigation and reduction of transient fat artifacts. Theoretical properties of a region-based shot rejection are described. The region-based shot rejection method was evaluated with free-breathing (normal and exaggerated breathing), and respiratory triggering. The proposed sequence was compared in vivo with multishot DW-EPI. The proposed sequence exhibits no evident distortion in vivo when compared to multishot DW-EPI, robustness to B0 and B1 field inhomogeneities, and robustness to motion from different respiratory patterns. Acquisition of distortionless, diffusion weighted images is feasible during free-breathing with a b-value of 500 s/mm2, scan time of 6 min, and a clinically viable reconstruction time.

Wearable Smart Silicone Belt for Human Motion Monitoring and Power Generation.

Human physical activity monitoring plays a crucial role in promoting personalized health management. In this work, inspired by an ancient Chinese belt, a belt-type wearable sensor (BWS) based on a triboelectric nanogenerator (TENG) is presented to monitor daily movements and collect the body motion mechanical energy. The developed BWS consists of a soft silicone sheet and systematically connected sensing units made from triboelectric polymer materials including polytetrafluoroethylene (PTFE) and polyamide (PA). A parameter study of the sensing units is firstly conducted to optimize the structure of BWS. The experimental studies indicate that the parameter-optimized BWS unit achieves a maximum output voltage of 47 V and a maximum current of 0.17 μA. A BWS with five sensing units is manufactured to record body movements, and it is able to distinguish different physical activities including stillness, walking, running, jumping, normal breathing, cessation of breathing, and deep breathing. In addition, the developed BWS successfully powers electronic devices including a smartphone, digital watch, and LED lights. We hope this work provides a new strategy for the development of wearable self-powered intelligent devices.

Wood Fiber-Based Triboelectric Material with High Filtration Efficiency and Antibacterial Properties and Its Respiratory Monitoring in Mask.

Self-powered wearable electronic products have rapidly advanced in the fields of sensing and health monitoring, presenting greater challenges for triboelectric materials. The limited surface polarity and structural defects in wood fibers restrict their potential as substitutes for petroleum-based materials. This study used bagasse fiber as the raw material and explored various methods, including functionalizing cellulose nanofibrils (CNFs) with polydopamine (PDA), in situ embedding of silver particles, filtration, and freeze-drying. These methods aimed to enhance the triboelectric output, antibacterial properties, and filtration properties of lignocellulosic materials. The Ag/PDA/CNF-based triboelectric nanogenerator (TENG) demonstrated an open-circuit voltage of 211 V and a short-circuit current of 18.1 μA. An aerogel prepared by freeze-drying the Ag/PDA/CNF material, combined with a polyvinylidene fluoride nanofiber structure fabricated by electrospinning, constitutes the TENG unit. A self-powered respiratory detection mask was created using this combination, achieving a filtration efficiency of 94.23% for 0.3 μm particles and an antibacterial rate exceeding 99%. In addition, it effectively responded to respiratory frequency signals of slow breathing, normal breathing, and shortness of breath, with the output electrical signal correlating with the respiratory frequency. This study considerably contributes to advancing wood fiber-based triboelectric materials as alternatives to petroleum-derived materials in self-powered wearable electronic products for medical applications.

Characterisation of sleep apneas and respiratory circuitry in mice lacking CDKL5.

CDKL5 deficiency disorder is a rare genetic disease caused by mutations in the CDKL5 gene. Central apneas during wakefulness have been reported in patients with CDKL5 deficiency disorder. Studies on CDKL5-knockout mice, a CDKL5 deficiency disorder model, reported sleep apneas, but it is still unclear whether these events are central (central sleep apnea) or obstructive (obstructive sleep apnea) and may be related to alterations of brain circuits that modulate breathing rhythm. This study aimed to discriminate central sleep apnea and obstructive sleep apnea in CDKL5-knockout mice, and explore changes in the somatostatin neurons expressing high levels of neurokinin-1 receptors within the preBötzinger complex. Ten adult male wild-type and 12 CDKL5-knockout mice underwent electrode implantation for sleep stage discrimination and diaphragmatic activity recording, and were studied using whole-body plethysmography for 7 hr during the light (resting) period. Sleep apneas were categorised as central sleep apnea or obstructive sleep apnea based on the recorded signals. The number of somatostatin neurons in the preBötzinger complex and their neurokinin-1 receptors expression were assessed through immunohistochemistry in a sub-group of animals. CDKL5-knockout mice exhibited a higher apnea occurrence rate and a greater prevalence of obstructive sleep apnea during rapid eye movement sleep, compared with wild-type, whereas no significant difference was observed for central sleep apnea. Moreover, CDKL5-knockout mice showed a reduced number of somatostatin neurons in the preBötzinger complex, and these neurons expressed a lower level of neurokinin-1 receptors compared with wild-type controls. These findings underscore the pivotal role of CDKL5 in regulating normal breathing, suggesting its potential involvement in shaping preBötzinger complex neural circuitry and controlling respiratory muscles during sleep.

Monitoring the Sleep Respiratory Rate with Low-Cost Microcontroller Wi-Fi in a Controlled Environment

Sleep apnea, characterized by breathing interruptions or slow breathing at night, can cause various health issues. Detecting respiratory rate (RR) using Wireless Fidelity (Wi-Fi) can identify sleep disorders without physical contact avoiding sleep disruption. However, traditional methods using Network Interface Cards (NICs) like the Intel Wi-Fi Link 5300 NIC are often costly and limited in channel state information (CSI) resolution. Our study introduces an effective strategy using the affordable ESP32 single-board computer for tracking RR through detailed analysis of Wi-Fi signal CSI. We developed a technique correlating Wi-Fi signal fluctuations with RR, employing signal processing methods—Hampel Filtering, Gaussian Filtering, Linear Interpolation, and Butterworth Low Pass Filtering—to accurately extract relevant signals. Additionally, noise from external movements is mitigated using a Z-Score for anomaly detection approach. We also implemented a local peak function to count peaks within an interval, scaling it to bpm for RR identification. RR measurements were conducted at different rates—Normal (12–16 bpm), Fast (>16 bpm), and Slow (<12 bpm)—to assess the effectiveness in both normal and sleep apnea conditions. Tested on data from 8 participants with distinct body types and genders, our approach demonstrated accuracy by comparing modeled sleep RR against actual RR measurements from the Vernier Respiration Monitor Belt. Optimal parameter settings yielded an overall average mean absolute deviation (MAD) of 2.60 bpm, providing the best result for normal breathing (MAD = 1.38). Different optimal settings were required for fast (MAD = 1.81) and slow breathing (MAD = 2.98). The results indicate that our method effectively detects RR using a low-cost approach under different parameter settings.

Multi-resolution assessment of heart rate variability signals during yogic and normal breathing using machine learning modules

In recent times, yoga has gained global prominence due to its wide-ranging health benefits. Heart rate variability (HRV) analysis has become a widely embraced tool to assess the impact of yoga and meditation on individuals. The effects of yoga can vary significantly among individuals based on their prior expertise, skills, and the interplay of external and internal dynamics. This variability complicates the task of extracting distinctive characteristics from raw data to categorize yogic and pre-yogic states. This paper introduces a new approach that enhances the screening of yogic states through multi-resolution analysis of HRV data combined with a machine learning module. The empirical Fourier decomposition (EFD) technique is harnessed to decompose input data into distinct multi-resolution modes. Various statistical characteristics are then extracted from these modes, allowing for a comprehensive analysis of the immediate effects of yoga breathing on HRV signals. To discern between yogic and pre-yogic HRV signals, a selection of significant features is ranked using a chi-square score and subsequently inputted into machine-learning modules. Notably, employing normalized features with the decision medium tree classifier yields an area under the curve (AUC) value of 0.99, while using direct features with an ensemble bagged tree classifier results in an AUC value of 0.82. Furthermore, this research underscores the importance of assessing outcomes from various metrics to compute the underlying dynamics of HRV data during breathing practices. This approach facilitates precise monitoring, personalized feedback, and intervention in yoga machine interfacing systems, ultimately enriching the overall experience and well-being of yoga practitioners.

Biophysical impact of lubricating base oil aerosols on natural pulmonary surfactant film

Lubricating base oils have been extensively employed for producing various industrial and consumer products. Therefore, their environmental and health impacts should be carefully evaluated. Although there have been many reports on pulmonary cytotoxicity and inflammatory responses of inhaled lubricating base oils, their potential influences on pulmonary surfactant (PS) films that play an essential role in maintaining respiratory mechanics and pulmonary immunity remains largely unknown. Here a systematic study on the interactions between an animal-derived natural PS and aerosols of water and representative mineral and vegetable base oils is performed using a novel biophysical assessing technique called constrained drop surfactometry capable of providing in vitro simulations of normal tidal breathing and physiologically relevant temperature and humidity in the lung. It was found that the mineral oil aerosols can impose strong inhibitions to the biophysical property of PS film, while the airborne vegetable oils and water show negligible adverse effects within the studied concentration range. The inhibitory effect is originated from the strong hydrophobicity of mineral oil, which makes it able to disrupt the interfacial molecular ordering of both phospholipid and protein compositions and consequently suppress the formation of condensed phase and multilayer scaffolds in a PS film. Environmental ImplicationUnderstanding the biophysical influence of airborne lubricating base oils on pulmonary surfactant (PS) films can provide new insights into the environmental impacts and health concerns of various industrial lubricant products. Here a comparative study on interactions between an animal-derived natural PS film and the aerosols of water and representative mineral and vegetable base oils under the true physiological conditions was conducted in situ using constrained drop surfactometry. We show that the most frequently used mineral base oil can cause strong inhibitions to the PS film by disrupting the molecular ordering of saturated phospholipids and surfactant-associated proteins at the interface.

Apnoea suppresses brain activity in infants

Abstract Apnoea—the cessation of breathing—is commonly observed in premature infants. These events can reduce cerebral oxygenation and are associated with poorer neurodevelopmental outcomes. However, relatively little is known about how apnoea and shorter pauses in breathing impact brain function in infants, which will provide greater mechanistic understanding of how apnoea affects brain development. We analysed simultaneous recordings of respiration, electroencephalography (EEG), heart rate, and peripheral oxygen saturation in 124 recordings from 118 infants (post-menstrual age: 38.6 ± 2.7 weeks [mean ± standard deviation]) during apnoeas (pauses in breathing greater than 15 seconds) and shorter breathing pauses between 5 and 15 seconds. EEG amplitude significantly decreased during both apnoeas and short breathing pauses compared with normal breathing periods. Change in EEG amplitude was significantly associated with change in heart rate during apnoea and short breathing pauses and, during apnoeas only, with oxygen saturation change. No associations were found between EEG amplitude changes and apnoea/pause duration, post-menstrual age, or sleep state. As apnoeas often occur in premature infants, frequent disruption to brain activity may impact neural development and result in long-term neurodevelopmental consequences.

Effectiveness of simultaneous bilateral visual diaphragm biofeedback under low back pain: influence of age and sex.

Introduction: The aim of the present study was to determine the effectiveness of simultaneous bilateral visual diaphragm biofeedback (BFB) from ultrasonography in conjunction with inspiratory muscle training (IMT) on diaphragmatic thickness during normal breathing and respiratory and clinical outcomes in patients with non-specific low back pain (NSLBP) and determine the influence of age and sex. Methods: A single-blind randomized clinical trial was carried out (NCT04582812). A total sample of 96 patients with NSLBP was recruited and randomized by sex-based stratification into IMT (n = 48) and BFB + IMT (n = 48) interventions over 8weeks. Bilateral diaphragmatic thickness at maximum inspiration (Tins) and expiration (Texp), respiratory pressures, lung function, pain intensity, bilateral pressure pain threshold (PPT), disability, and quality of life were measured at baseline and after 8weeks. Results: The BFB + IMT group showed significant differences (p < 0.05) with increased left hemidiaphragm thickness at Tins and Tins-exp (d = 0.38-053), and right and left PPT (d = 0.71-0.74) versus the IMT group. The interaction with sex was statistically significant (p = 0.007; F(1,81) = 7.756; ηp 2 = 0.087) and higher left hemidiaphragm thickness at Tins was predicted by the BFB + IMT group (R 2 = 0.099; β = 0.050; F(1,82) = 8.997; p = 0.004) and male sex (R 2 = 0.079; β = 0.045; F(1,81) = 7.756;p = 0.007). Furthermore, greater left hemidiaphragm thickness at Tins-exp was predicted by younger age (R 2 = 0.052; β = -0.001; F(1,82) = 4.540; p = 0.036). Discussion: The simultaneous bilateral visual diaphragm biofeedback by ultrasonography in conjunction with IMT was effective in both increasing the left diaphragmatic thickness during inspiration, which was positively influenced and predicted by male sex and younger age, and increasing the bilateral PPT of the paraspinal muscles in patients with NSLBP.

Deep abdominal breathing reduces heart rate and symptoms during orthostatic challenge in patients with postural orthostatic tachycardia syndrome.

This study investigated the effects of deep abdominal breathing on cardiovascular parameters and symptoms in patients with postural orthostatic tachycardia syndrome (POTS) during head-up tilt-table (HUT) challenge. Thirty POTS patients completed two consecutive rounds of 10-min HUT in a crossover design. One round was HUT without intervention, and one round combined the HUT with deep breathing at a rate of 6 breaths/min. Cardiovascular parameters, including mean blood pressure and maximum and mean heart rate (HR), were measured supine and standing. Symptoms were assessed using the Vanderbilt Orthostatic Symptom Score (VOSS). During the breathing technique, the mean HR increase was -7.35 bpm (95% confidence interval [CI] = -11.71 to -2.98), and the maximum HR increase was -6.27 bpm (95% CI = -11.85 to -0.68, p = 0.041), significantly lower compared to normal breathing. Additionally, improvements were observed in all absolute cardiovascular parameters during standing, with VOSS symptoms simultaneously and significantly decreasing by -5.38 (95% CI = -10.43 to -0.36). Slow deep abdominal breathing can act as a simple technique to reduce the standing HR increase upon HUT in patients with POTS. This suggests that modulation of the cardiopulmonary neurocircuits and the respiratory pump may reduce HR increase and symptoms in patients with POTS. The findings of this study highlight the use of a safe, zero-cost, and simple behavioral tool to suggest to POTS patients for symptom relief apart from standard treatment. The observed improvements in cardiovascular parameters and symptoms offer a promising therapeutic approach for patients in times of inadequate treatment options.

MmWave-RM: A Respiration Monitoring and Pattern Classification System Based on mmWave Radar.

Breathing is one of the body's most basic functions and abnormal breathing can indicate underlying cardiopulmonary problems. Monitoring respiratory abnormalities can help with early detection and reduce the risk of cardiopulmonary diseases. In this study, a 77 GHz frequency-modulated continuous wave (FMCW) millimetre-wave (mmWave) radar was used to detect different types of respiratory signals from the human body in a non-contact manner for respiratory monitoring (RM). To solve the problem of noise interference in the daily environment on the recognition of different breathing patterns, the system utilised breathing signals captured by the millimetre-wave radar. Firstly, we filtered out most of the static noise using a signal superposition method and designed an elliptical filter to obtain a more accurate image of the breathing waveforms between 0.1 Hz and 0.5 Hz. Secondly, combined with the histogram of oriented gradient (HOG) feature extraction algorithm, K-nearest neighbours (KNN), convolutional neural network (CNN), and HOG support vector machine (G-SVM) were used to classify four breathing modes, namely, normal breathing, slow and deep breathing, quick breathing, and meningitic breathing. The overall accuracy reached up to 94.75%. Therefore, this study effectively supports daily medical monitoring.

Apnea or normal breathing during repeated high-intensity swimming enhance sprint efficiency and which metabolic disorder?

The aim of this study was to investigate the effect of normal breath and apnea swimming on acid-base balance, physiological responses and performance during high-intensity interval training in swimming. Sixteen swimmers completed 6×50 m intervals of freestyle swimming with normal breath and apnea at maximum intensity, with 1 minute rest. Capillary blood gases (pH, PCO<inf>2</inf>, PO<inf>2</inf>, HCO<inf>3</inf>, Hct, Hb) were collected at four (4) measurement time points: 1) at rest once; 2) at rest just after the 3rd repetition; 3) at finish; and 4) at 10 min of recovery. Heart rate (HR) during swimming, lactate acid (La) concentration and swimming time (t<inf>50</inf>) were measured. Our study showed uncompensated metabolic acidosis due to increased lactic acidosis in both breathing conditions, more pronounced in apnea, and faster swimming times in apnea without different heart rate responses. Apnea during repetitive high intensity long distance interval 50 m freestyle swimming causes uncompensated metabolic acidosis but improves sprint performance.

Validation study of a novel diaphragmatic excursion measurement method: evaluation of diaphragmatic excursion by phased-array probe in hepato-renal/spleno-renal section

To investigate the accuracy and reproducibility of diaphragmatic excursion (DE) measurements through hepato-renal/spleno-renal section as a novel method for assessing diaphragmatic function. Twelve healthy participants were recruited. Each participant underwent DE measurements performed by four operators with varying levels of experience using traditional methods (liver/spleen section) and novel methods (hepato-renal/spleno-renal section), respectively. Among them, two experienced operators were critical care clinicians, and diaphragmatic ultrasound was performed in more than 50 cases. The other two inexperienced operators were respiratory therapists, with less than 10 cases of diaphragmatic ultrasound operations, who received a 2-hour theoretical and operational training before the study. Operators initially used the conventional method with a 1.5-6.0 MHz convex probe in M-mode, placing the sampling line perpendicular to the diaphragm at the point of maximum excursion, and the liver/spleen section DE was determined during normal breathing of participant. Then, they used the novel method with a 1.6-4.5 MHz phased array probe to observe diaphragmatic movement cranio-caudally along the mid-axillary line, employing anatomic M-mode with the sampling line placed perpendicular to the diaphragm at the level of the renal midpoint, and the DE of the hepato-renal/spleno-renal section was measured during normal breathing. The liver and hepato-renal sections were used to assess the right diaphragm, and spleen and spleno-renal sections were used to assess the left diaphragm. Correlation analysis of DE measurements from different sections was conducted using the Deming method, while consistency was assessed using the Bland-Altman method. The consistency of clinical acceptability was defined as the absence of fixed and proportional bias, with a difference of two standard deviations less than 40% of the mean measurement value. Percentage consistency limit = two standard deviations of the differences between measurements/mean measurement value×100%. Four operators performed image scans of DE in all four sections for each of the twelve subjects, with a high DE acquisition rate of 100% (48/48) for hepato-renal and spleno-renal sections, followed by the liver section [91.7% (44/48)] and the spleen section [66.7% (32/48)], particularly for the left diaphragm assessment, where the DE acquisition rate of spleno-renal section was significantly higher than that of traditional spleen section (P < 0.01). The overall measurement results showed that no significant difference was found in DE determined via the hepato-renal and spleno-renal sections using the novel method (cm: 1.64±0.10 vs. 1.55±0.14, P > 0.05), and they were significantly higher than those determined via the conventional liver and spleen sections (cm: hepato-renal section vs. liver section was 1.64±0.10 vs. 1.44±0.09, spleno-renal section vs. spleen section was 1.55±0.14 vs. 1.09±0.14, both P < 0.01). Correlation analysis revealed good correlations of DE between hepato-renal section and spleno-renal section, between liver section and hepato-renal section, between liver section and spleno-renal section (r values were 0.62, 0.59, and 0.42, all P < 0.01). Consistency analysis showed that the consistency in DE between hepato-renal section and spleno-renal section, as well as between liver section and hepato-renal section was good (both % consistency limits < 40%). However, the DE measured in the spleen section were not correlated with the other three sections, and there was no inconsistency (all % consistency limits > 40%). There was no statistically significant difference in DE measured by the four operators in the liver, spleen, hepato-renal, and spleno-renal sections (cm: 1.49±0.34, 1.44±0.37, 1.43±0.30, and 1.40±0.27 in liver section; 1.10±0.36, 1.05±0.18, 1.09±0.22, and 1.06±0.26 in spleen section; 1.67±0.43, 1.57±0.34, 1.63±0.32, and 1.66±0.36 in hepato-renal section; 1.45±0.33, 1.48±0.34, 1.50±0.24, and 1.65±0.26 in spleno-renal section; all P > 0.05). According to the clinically acceptable range of consistency limits, the DE measured by the four operators in all four sections showed good consistency (all % consistency limits < 40%). The novel method of measuring DE through hepato-renal/spleno-renal sections is accurate, highly reproducible, and has a high acquisition rate, serving as a viable alternative to the conventional method involving the liver/spleen section.

Validation of Tracheal Sound-Based Respiratory Effort Monitoring for Obstructive Sleep Apnoea Diagnosis.

Background: Respiratory effort is considered important in the context of the diagnosis of obstructive sleep apnoea (OSA), as well as other sleep disorders. However, current monitoring techniques can be obtrusive and interfere with a patient's natural sleep. This study examines the reliability of an unobtrusive tracheal sound-based approach to monitor respiratory effort in the context of OSA, using manually marked respiratory inductance plethysmography (RIP) signals as a gold standard for validation. Methods: In total, 150 patients were trained on the use of type III cardiorespiratory polygraphy, which they took to use at home, alongside a neck-worn AcuPebble system. The respiratory effort channels obtained from the tracheal sound recordings were compared to the effort measured by the RIP bands during automatic and manual marking experiments. A total of 133 central apnoeas, 218 obstructive apnoeas, 263 obstructive hypopneas, and 270 normal breathing randomly selected segments were shuffled and blindly marked by a Registered Polysomnographic Technologist (RPSGT) in both types of channels. The RIP signals had previously also been independently marked by another expert clinician in the context of diagnosing those patients, and without access to the effort channel of AcuPebble. The classification achieved with the acoustically obtained effort was assessed with statistical metrics and the average amplitude distributions per respiratory event type for each of the different channels were also studied to assess the overlap between event types. Results: The performance of the acoustic effort channel was evaluated for the events where both scorers were in agreement in the marking of the gold standard reference channel, showing an average sensitivity of 90.5%, a specificity of 98.6%, and an accuracy of 96.8% against the reference standard with blind expert marking. In addition, a comparison using the Embla Remlogic 4.0 automatic software of the reference standard for classification, as opposed to the expert marking, showed that the acoustic channels outperformed the RIP channels (acoustic sensitivity: 71.9%; acoustic specificity: 97.2%; RIP sensitivity: 70.1%; RIP specificity: 76.1%). The amplitude trends across different event types also showed that the acoustic channels exhibited a better differentiation between the amplitude distributions of different event types, which can help when doing manual interpretation. Conclusions: The results prove that the acoustically obtained effort channel extracted using AcuPebble is an accurate, reliable, and more patient-friendly alternative to RIP in the context of OSA.

Sigh generation in preBötzinger Complex.

We explored neural mechanisms underlying sighing. Photostimulation of parafacial (pF) neuromedin B (NMB) or gastrin releasing peptide (GRP), or preBötzinger Complex (preBötC) NMBR or GRPR neurons elicited ectopic sighs with latency inversely related to time from preceding endogenous sigh. Of particular note, ectopic sighs could be produced without involvement of these peptides or their receptors in preBötC. Moreover, chemogenetic or optogenetic activation of preBötC SST neurons induced sighing, even in the presence of NMBR and/or GRPR antagonists. We propose that an increase in the excitability of preBötC NMBR or GRPR neurons not requiring activation of their peptide receptors activates partially overlapping pathways to generate sighs, and that preBötC SST neurons are a downstream element in the sigh generation circuit that converts normal breaths into sighs.

A Secondary Analysis of Gender Respiratory Features for Ultrasonography Bilateral Diaphragm Thickness, Respiratory Pressures, and Pulmonary Function in Low Back Pain.

The aim of the present study was to determine the gender respiratory differences of bilateral diaphragm thickness, respiratory pressures, and pulmonary function in patients with low back pain (LBP). A sample of 90 participants with nonspecific LBP was recruited and matched paired by sex (45 women and 45 men). Respiratory outcomes included bilateral diaphragm thickness by ultrasonography, respiratory muscle strength by maximum inspiratory (MIP) and expiratory (MEP) pressures, and pulmonary function by forced expiratory volume during 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC spirometry parameters. The comparison of respiratory outcomes presented significant differences (p < 0.001), with a large effect size (d = 1.26-1.58) showing means differences (95% CI) for MIP of -32.26 (-42.99, -21.53) cm H2O, MEP of -50.66 (-64.08, -37.25) cm H2O, FEV1 of -0.92 (-1.18, -0.65) L, and FVC of -1.00 (-1.32, -0.69) L, with lower values for females versus males. Gender-based respiratory differences were presented for maximum respiratory pressures and pulmonary function in patients with nonspecific LBP. Women presented greater inspiratory and expiratory muscle weakness as well as worse lung function, although these differences were not linked to diaphragm thickness during normal breathing.

The Structure of Digestive Tract Coordinating Digestion and Respiration in an Air-Breathing Weatherloach, Misgurnus anguillicaudatus.

To clarify how the digestive tract of the weatherloach, Misgurnus anguillicaudatus, serves a dual function of digestion and respiration simultaneously, the histological structures of its digestive tract, the passage of digesta and air passing through its intestine and the rate of intestinal evacuation have been studied. The results indicate that the digestive tract is divided into five functional regions, i.e., esophagus, anterior intestine, middle intestine, posterior intestine and rectum. The diverse intestinal structures have the specialized function of coordinating digestion and respiration. An X-ray barium meal examination showed in the normal breathing state, the contents of the intestine are diffusely semifluid, and air is distributed as bubbles in the dorsal intestine 2 h after feeding. After 5 h, the contents accumulated in the mid and posterior intestine, and gas flowed above the contents as bundles. After 8 h, the intestinal food was basically evacuated. In the intestinal air-breathing restricted group, the contents of the intestine remained diffuse, and a large number of digesta entered and remained in the rectum after 5 h. After the inhibition was relieved, the contents of the rectum were rapidly discharged. Measurement of the intestinal evacuation rate in the intestine showed that the evacuation of the intestinal contents lagged behind that of the normal group in the air-breathing restricted group. Compared to the normal state and inhibited GAB (gastrointestinal air breathing), we could deduce that GAB could promote the movement of the intestine.