Normal Human Breath Research Articles

Highly stretchable anti-freeze hydrogel based on aloe polysaccharides with high ionic conductivity for multifunctional wearable sensors

Conductive hydrogels have limitations such as non-degradability, loss of electrical conductivity at sub-zero temperatures, and single functionality, which limit their applicability as materials for wearable sensors. To overcome these limitations, this study proposes a bio-based hydrogel using aloe polysaccharides as the matrix and degradable polyvinyl alcohol as a reinforcing material. The hydrogel was crosslinked with borax in a glycerol–water binary solvent system, producing good toughness and compressive strength. Furthermore, the hydrogel was developed as a sensor that could detect both small and large deformations with a low detection limit of 1 % and high stretchability of up to 300 %. Moreover, the sensor exhibited excellent frost resistance at temperatures above −50 °C, and the gauge factor of the hydrogel was 2.86 at 20 °C and 2.12 at −20 °C. The Aloe-polysaccharide-based conductive hydrogels also functioned effectively as a wearable sensor; it detected a wide range of humidities (0–98 % relative humidity) and exhibited fast response and recovery times (1.1 and 0.9 s) while detecting normal human breathing. The polysaccharide hydrogel was also temperature sensitive (1.737 % °C−1) and allowed for information sensing during handwriting.

Electronic Auscultation System: Processing of Auscultatory Data

The purpose of research is to increase the diversity of electronic auscultation system designs with measured characteristics and testing. The series of articles includes the development of a model of the electronic auscultation system, the design of an electronic stethoscope, the manufacture of an experimental sample, the development of a methodology for measuring the amplitude-frequency characteristics of electronic and classical stethoscopes, testing of the proposed models and methods, analysis of auscultative data. The article considers mathematical methods of primary analysis of auscultative data. Recordings of normal and hard breathing were used for the experiment. Frequency, time-frequency and autocorrelation analysis of respiratory sounds was performed. Methods. The research was based on the theory of digital signal processing. The study uses auscultative data obtained from an experimental sample of an electronic auscultation system. Electronic records of hard (pathological) and normal human breathing over the left middle lung were used. Respiratory noises were converted into digital form with the following parameters: sampling frequency fd = 48 kHz; bit depth n = 24 bits; number of channels 1. To analyze the frequency information content of the recordings, their spectra were constructed. A fast Fourier transform was used to calculate the values in the spectra. Results. In the presented work, the frequency characteristics of recordings of hard and normal breathing are analyzed. The values of autocorrelation functions are obtained. An author-regression model of the process of normal breathing is obtained. The problem of analytical determination of the model order remains open and requires a separate solution. The resulting model allows you to generate an equivalent breathing noise of inhalation or exhalation when a signal with a uniform is applied to its input. Conclusion. A sample of the electronic auscultation system has been tested, methods of simplified primary analysis of auscultative data have been proposed. The difference in the results of the treatment of hard and normal breathing has no statistical significance due to the small sample.

Assessment of airborne transmission from coughing processes with thermal plume adjacent to body and radiators on effectiveness of social distancing.

The new coronavirus disease COVID-19 has caused a worldwide pandemic to be declared in a very short period of time. The complexity of the infection lies in asymptomatic carriers that can inadvertently transmit the virus through airborne droplets. This kind of viral disease can infect the human body with tiny particles that carry various bacteria that are generated by the respiratory system of infected patients. In this study, numerical results are proposed that demonstrate the effect of human body temperature and temperature from radiators in a room on the spread of the smallest droplets and particles in an enclosed space. The numerical model proposed in this work takes into account the sedimentation of particles and droplets under the action of gravitational sedimentation and transport in a closed room during the processes of breathing, sneezing or coughing. Various cases were considered, taking into account normal human breathing, coughing or sneezing, as well as three different values of the rate of emission of particles from the human mouth. The heat plume, which affects the concentration of particles in the breathing zone, spreads the particle up to a distance of 4.29m in the direction of the air flow. It can also be seen from the results obtained that the presence of radiators strongly affects the propagation of particles of various sizes in a closed room. From the obtained results, it should be noted that in order to recommend the optimal social distance, it is necessary to take into account many factors, especially momentum, gravity, human body temperature, as well as the process of natural convection, which greatly affect the propagation of particles in a closed room. The conclusions drawn from the results of this work show that, given the environmental conditions, the social distance of 2m may not be enough.

On the Lagrangian dynamics of saliva particles during normal mouth breathing

The flow and saliva particulate transport dynamics during normal human breathing through the mouth are simulated numerically using an Eulerian large-eddy simulation (LES) approach for the flow coupled with a Lagrangian approach for the transport of saliva particles. The coupled Eulerian–Lagrangian (EL) simulation results reveal new striking insights into the rich dynamics of the Lagrangian coherent structures (LCS) that arise from saliva particles during normal breathing. Specifically, they uncover a new time-periodic mechanism via which particles are introduced into the flow as individual breathing pulses and accumulate to form a slowly propagating vortex front that persists long distances away from the source. The simulated LCS reveal a wealth of recurrent material motion through which the biosols propagate forward while their cloud expands laterally with a slowly evolving vortex front. Also, the finite-time Lyapunov exponent (FTLE) field of human breathing was calculated using the flow map from the LES velocity field. The ridges of the calculated FTLE field revealed distinct hyperbolic LCS, which closely resemble trajectories of saliva particles obtained from the coupled EL simulation. Finally, simulation results for normal breathing with a non-medical face mask show that the mask can effectively disrupt the formation of coherent particle surfaces and, thus, effectively limit saliva particle propagation.

In silico study of airway/lung mechanics in normal human breathing

The airway/lung mechanics is usually represented with nonlinear 0-D models based on a pneumatic-electrical analogy.The aim of this work is to provide a detailed description of the human respiratory mechanics in healthy and diseased conditions. The model used for this purpose employs some known constitutive functions of the main components of the respiratory system. We give a detailed mathematical description of these functions and subsequently derive additional key ones. We are interested not only in the main output such as airflow at the mouth or alveolar pressure and volume, but also in other quantities such as resistance and pressure drop across each element of the system and even recoil and compliance of the chest wall.Pathological conditions are simulated by altering the parameters of the constitutive functions. Results show that increased upper airway resistance induces airflow reduction with concomitant narrowing of volume and pressure ranges without affecting lung compliance. Instead, increased elastic recoil leads to low volumes and decreased lung compliance.The model could be used in the study of the interaction between respiratory and cardiovascular systems in pathophysiological conditions.

Calibration-free breath acetone sensor with interference correction based on wavelength modulation spectroscopy near 8.2 $$\upmu$$m

Development of a robust breath acetone sensor based on laser absorption of multiple species near 8.2 $$\upmu$$m is presented. A scanned-wavelength modulation spectroscopy technique, involving intensity-normalized second harmonic detection, was paired with a multi-pass optical gas cell to attain signals related to differential absorbance of acetone, water vapor, and methane. A spectral fitting routine of the harmonic signals was used to infer the respective abundances of each species, correcting the acetone signal for interfering absorption. A detection limit ($$2\sigma$$) of approximately 0.11 ppm acetone was determined based on controlled measurements using reference test gases. The sensor was further tested in exhaled breath samples with varying amounts of interfering species, exhibiting capability for sensitive acetone detection with very high levels of exhaled methane (up to 40 ppm). The sensor is also shown to be insensitive to locally broadband interfering absorbers, namely methanol and ethanol in normal human breath. To highlight utility, the breath acetone sensor was used to track ketosis during a regimented ketogenic diet of several subjects, demonstrating regular non-intrusive monitoring of breath acetone over a clinically-relevant range (0.4–74 ppm) and sensitivity to dietary changes.

Experimental and numerical investigation on composite phase change material (PCM) based heat exchanger for breathing air cooling

In the field of human survivability in elevated temperature situations such as firefighting, inhalation injuries cause a much higher mortality rate than skin burns. Conventional rescue respirators merely deal with the filtering of the toxics and smokes, while cooling left out of their consideration. This work aims to fill the gap. In this work, we propose a new scheme by utilizing the paraffin/expanded graphite composite materials to construct a heat exchanger. The material itself plays the mechanical support, the heat spreader and the heat absorber at the same time, which circumvents the use of multi-level designs. In the enclosure or semi-enclosure fire, the 500 K hot air flows through the heat exchanger and is cooled down to breathable temperature (<313 K). By normal human breath flux, this process can sustain for more than 20 min for personnel emergency escape. We also discussed the optimized conditions of material parameters and structural configurations. We suggested that these optimum conditions may subject to change in varying scenarios. This work is promising as a comprehensive solution to the breathing air cooling problem, while demonstrating the methodology for solving similar problems.

How Normal Breathing Rate Can Affect Nail Biting Habit

Objective of the present study was to find the effects of normal breathing rate on nail biting habit. In present study, total 140 subjects participated. These all participants were the students of Bahauddin Zakariya University, Multan, Pakistan. In present study, survey based training had given an important advancement. Watch was used to calculate normal human breathing rate per minute. Subjects were allowed to sit in normal condition. Then one by one their breathing rate was calculated. After that asked question from them about their nail biting habit and put their breathing rate values in yes or no portion according to their answers. Concluded from recent research that there is no effect of normal breathing rate on nail biting habit

Classification of Asthma Based on Nonlinear Analysis of Breathing Pattern.

Normal human breathing exhibits complex variability in both respiratory rhythm and volume. Analyzing such nonlinear fluctuations may provide clinically relevant information in patients with complex illnesses such as asthma. We compared the cycle-by-cycle fluctuations of inter-breath interval (IBI) and lung volume (LV) among healthy volunteers and patients with various types of asthma. Continuous respiratory datasets were collected from forty age-matched men including 10 healthy volunteers, 10 patients with controlled atopic asthma, 10 patients with uncontrolled atopic asthma, and 10 patients with uncontrolled non-atopic asthma during 60 min spontaneous breathing. Complexity of breathing pattern was quantified by calculating detrended fluctuation analysis, largest Lyapunov exponents, sample entropy, and cross-sample entropy. The IBI as well as LV fluctuations showed decreased long-range correlation, increased regularity and reduced sensitivity to initial conditions in patients with asthma, particularly in uncontrolled state. Our results also showed a strong synchronization between the IBI and LV in patients with uncontrolled asthma. Receiver operating characteristic (ROC) curve analysis showed that nonlinear analysis of breathing pattern has a diagnostic value in asthma and can be used in differentiating uncontrolled from controlled and non-atopic from atopic asthma. We suggest that complexity analysis of breathing dynamics may represent a novel physiologic marker to facilitate diagnosis and management of patients with asthma. However, future studies are needed to increase the validity of the study and to improve these novel methods for better patient management.

A MEMS turbine prototype for respiration harvesting

The design, manufacturing, and performance characterization of a MEMS-scale turbine prototype is reported. The turbine is designed for integration into a respiration harvester that can convert normal human breathing into electrical power through electromagnetic induction. The device measures 10 mm in radius, and employs 12 blades located around the turbine periphery along with ball bearings around the center. Finite element simulations showed that an average torque of 3.07 μNm is induced at 12 lpm airflow rate, which lies in normal breathing levels. The turbine and a test package were manufactured using CNC milling on PMMA. Tests were performed at respiration flow rates between 5-25 lpm. The highest rotational speed was measured to be 9.84 krpm at 25 lpm, resulting in 8.96 mbar pressure drop across the device and 370 mW actuation power.

Breath tests in diagnosis of pulmonary tuberculosis.

Since the time of Hippocrates, physicians have known that the odour of human breath can provide clues to diagnosis. In the past, hydrogen peroxide which is a marker of inflammatory diseases and oxidative stress was the most studied substance in the exhaled breath which was detectable in the liquid that obtained by condensing or cooling. The advantages of breath analysis are that it is convenient, non-invasive, and could be performed with children as well as mechanically ventilated patients. Today, exhaled nitric oxide has been studied extensively, especially in relation to asthma. More than a thousand different volatile organic compounds have been observed in low concentrations in normal human breath. Alkanes and methylalkanes have been increasingly used by physicians as a novel method to diagnose many diseases without discomforts of invasive procedures. Although the limitations of measurement of exhaled nitric oxide in direct diagnosis of infectious pulmonary TB, it may have potential development as a cost-effective replacement of chest radiological examination in screening algorithms. None of the individual exhaled volatile organic compound alone is specific for disease. Exhaled breath analysis techniques may be available to diagnose and monitor the diseases in home setting when their sensitivity and specificity are expected to improve in the future. Here, we also discussed some patents related to the topic.

Point of Care Monitoring of Hemodialysis Patients with a Breath Ammonia Measurement Device Based on Printed Polyaniline Nanoparticle Sensors

A device for measuring human breath ammonia was developed based on a single use, disposable, inkjet printed ammonia sensor fabricated using polyaniline nanoparticles. The device was optimized for sampling ammonia in human breath samples by addressing issues such as variations in breath sample volume, flow rate, sources of oral ammonia, temperature and humidity. The resulting system was capable of measuring ammonia in breath from 40 to 2993 ppbv (r(2)= 0.99, n = 3) as correlated with photoacoustic laser spectroscopy and correlation in normal human breath samples yielded a slope of 0.93 and a Pearson correlation coefficient of 0.9705 (p < 0.05, n = 11). Measurement of ammonia in the breath of patients with end-stage kidney disease demonstrated its significant reduction following dialysis, while also correlating well with blood urea nitrogen (BUN) (r = 0.61, p < 0.01, n = 96). Excellent intraindividual correlations were demonstrated between breath ammonia and BUN (0.86 to 0.96), which demonstrates the possibility of using low cost point of care breath ammonia systems as a noninvasive means of monitoring kidney dysfunction and treatment.

Detection of an extended human volatome with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

BackgroundComprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOF MS) has been proposed as a powerful new tool for multidimensional analysis of complex chemical mixtures. We investigated GCxGC-TOF MS as a new method for identifying volatile organic compounds (VOCs) in normal human breath.MethodsSamples of alveolar breath VOCs and ambient room air VOC were collected with a breath collection apparatus (BCA) onto separate sorbent traps from 34 normal healthy volunteers (mean age = 40 yr, SD = 17 yr, male/female = 19/15). VOCs were separated on two serial capillary columns separated by a cryogenic modulator, and detected with TOF MS. The first and second dimension columns were non-polar and polar respectively.ResultsBCA collection combined with GC×GC-TOF MS analysis identified approximately 2000 different VOCs in samples of human breath, many of which have not been previously reported. The 50 VOCs with the highest alveolar gradients (abundance in breath minus abundance in ambient room air) mostly comprised benzene derivatives, acetone, methylated derivatives of alkanes, and isoprene.ConclusionsCollection and analysis of breath VOCs with the BCA-GC×GC-TOF MS system extended the size of the detectable human volatile metabolome, the volatome, by an order of magnitude compared to previous reports employing one-dimensional GC-MS. The size of the human volatome has been under-estimated in the past due to coelution of VOCs in one-dimensional GC analytical systems.

Volatile organic compounds in normal human exhaled breath, a long neglected pollutant source

At present, indoor VOCs pollution was widespread concerned. However, for human emission of VOCs, fundamental data was in shortage in the field of indoor air quality (IAQ). In this study, 11 male su...

Breath Tests in Respiratory and Critical Care Medicine: From Research to Practice in Current Perspectives

Today, exhaled nitric oxide has been studied the most, and most researches have now focusd on asthma. More than a thousand different volatile organic compounds have been observed in low concentrations in normal human breath. Alkanes and methylalkanes, the majority of breath volatile organic compounds, have been increasingly used by physicians as a novel method to diagnose many diseases without discomforts of invasive procedures. None of the individual exhaled volatile organic compound alone is specific for disease. Exhaled breath analysis techniques may be available to diagnose and monitor the diseases in home setting when their sensitivity and specificity are improved in the future.

Influence of ambient air on NMR-based metabolomics of exhaled breath condensates

To the Editors: Nuclear magnetic resonance (NMR)-based metabolomic analysis of exhaled breath condensate (EBC) is a noninvasive approach that has been used to study diseases of the respiratory system [1, 2]. In a previous study, we questioned the accuracy of NMR-based EBC analysis, demonstrating that the cleaning protocols for reusable condenser parts produce a confounding metabolite fingerprint largely unrelated to the endogenous metabolites from the airways and alveolar fractions of exhaled breath [3]. Here we present new data that provide a qualitative assessment of exogenous contaminants in NMR spectroscopy analysis of EBC, some proceeding from room air. Given the presence of these contaminants in the NMR spectrum, classification of these components as biomarkers of lung function should be regarded with extreme caution. Previous studies have reported the presence of room air components in mass spectrometry analysis of volatiles in exhaled human breath [4, 5] and non-volatiles in exhaled human breath condensate [6]. However, although a previous NMR-based metabolomic study of EBC reported the presence of external impurities such as disinfectants or salivary signals [1], the influence of contaminating metabolites in room air was not considered. In order to analyse the influence of exogenous signals on EBC analysis, room air condensate and EBC from a healthy volunteer were collected with an EcoScreen condenser (Jaeger, Wurzburg, Germany). The samples of room air condensate were acquired with a device that continuously pumps room air into the condenser at a flow rate (15 L·min−1) and tidal volume (500 mL) typical of normal human breathing. The typical time required for sample acquisition was 15 min. Another set of room air samples was collected by locating a trap for air-contained water-soluble organic compounds between the pump and the condenser to study the …

Deposition of Man-Made Fibers in a Human Nasal Airway

Many occupational lung diseases are associated with exposure to aerosolized fibers in the workplace. The nasal airway is a critical route for fiber aerosol to enter the human respiratory tract. The fiber deposition efficiency in the nasal airway could be used as an index to indicate the fraction of the inhaled fibers potentially transported to the lower airways. In this research, experiments of fiber deposition in the human nasal airway were conducted. Man-made carbon, glass, and titanium dioxide fibers in the inertia regime were used as the test fiber materials. The deposition studies were carried out by delivering aerosolized fibers into a human nasal airway replica at constant human inspiratory flow rates ranging from 15 l/min to 43.5 l/min. The deposition results were compared in detail between these fiber materials to study how the fiber characteristics affected the nasal airway deposition. The results showed that the deposition efficiency of the carbon fiber increases as the fiber impaction parameter increases. Many carbon fibers deposited in the anterior region of the nasal airway. In contrast, very few glass or titanium dioxide fibers deposited in the nasal airway, but relatively more of these two fibers deposited in the turbinate region. This result implies that, if a fiber in the inertia regime is inhaled during normal human breathing, the smaller the fiber, the more easily it could enter the human lower respiratory tract, possibly causing harm to the human respiratory tract.

Diversity and seasonal variation of viable algal particles in the atmosphere of a subtropical city in India

To characterize the airborne algal diversity in a populous subtropical urban environment, sampling was done at a height of 2.5 m, the normal human breathing zone. Results indicated that airborne algae are the permanent constituent of Varanasi city atmosphere. The nature, composition, and relative ratio of constituting groups differed among sampling sites. Cyanobacteria, possibly due to their broad ecological distribution, dominate the fluctuating climates of subtropical regions such as Varanasi. The majority of the airborne algae were of local origin, indicating short-distance transport of the algae. Soilborne algae constituted the bulk of aeroalgal flora. This might be due to their ability to withstand the dehydrating effect of the atmosphere. Composition of the aeroalgal community also exhibited seasonal variation along with the change in climatic condition of the area. Thus, the physiological ability of an algal group to tolerate different types of abiotic stresses and the climatic conditions of the area appeared to be the two major factors responsible for regulating the structure of the aeroalgal community in the air.

Respiratory-related activation and mechanical effects of the pharyngeal constrictor muscles

We have examined the respiratory-related activation of pharyngeal constrictor (PC) muscles in decerebrate cats, normal adult humans and patients with obstructive sleep apnea. In decerebrate cats and awake normal adult humans, phasic expiratory PC activity is uniformly present under hypercapnic and hypoxic conditions. While the PC muscles are electrically silent during quiet breathing in normal adult humans in NREM sleep, an activation pattern very similar to that of other upper airway dilators, such as the genioglossus muscle, is present during spontaneous and induced apneas in patients with obstructive sleep apnea. Experiments using an isolated, sealed upper airway preparation in decerebrate cat show that selective activation of the PC muscles stiffens the pharyngeal airway. The results also show that activation of the PC muscles constricts the airway at relatively high airway volumes but dilates the airway at relatively low airway volumes. These results suggest that PC muscle activation at the end of an apneic episode, when airway volume is relatively low, may help restore airway patency in patients with obstructive sleep apnea.

Effect of age on the profile of alkanes in normal human breath

Ethane and pentane in breath are markers of oxidative stress, produced by ROS-mediated lipid peroxidation of n-3 and n-6 polyunsaturated fatty acids (PUFAs), but little is known about other n-alkanes in normal human breath. We investigated the spectrum of alkanes in normal human alveolar breath, and their variation with age. Fifty normal humans were studied (age range 23–75, median 35). Volatile organic compounds (VOCs) in alveolar breath were captured on sorbent traps and assayed by gas chromatography and mass spectroscopy. Alveolar gradients (concentration in breath minus concentration in ambient room air) of alkanes were determined. C4–C20 alkanes were observed in breath and room air. Their mean alveolar gradients were negative from C4 to C12 and positive from C13 to C20. The mean alveolar gradients of four alkanes (C5–C8) were significantly less negative in the older subjects (p < 0.05). There were no significant differences between males and females. Normal human breath contained a spectrum of alkanes which may include new markers of oxidative stress. The mean rate of clearance (via cytochrome p450) exceeded the mean rate of synthesis (by ROS-mediated oxidative stress) for C4–C12 alkanes, while synthesis was greater than clearance for C13–C20 alkanes. The elevated alkane profile in older subjects was consistent with an age-related increase in oxidative stress, though an age-related decline in alkane clearance rate may have contributed.