Expiratory braking defines the breathing patterns of asphyxiated neonates during therapeutic hypothermia.

Introduction: Although neonatal breathing patterns vary after perinatal asphyxia, whether they change during therapeutic hypothermia (TH) remains unclear. We characterized breathing patterns in infants during TH for hypoxic-ischemic encephalopathy (HIE) and normothermia after rewarming. Methods: In seventeen spontaneously breathing infants receiving TH for HIE and in three who did not receive TH, we analyzed respiratory flow and esophageal pressure tracings for respiratory timing variables, pulmonary mechanics and respiratory effort. Breaths were classified as braked (inspiratory:expiratory ratio ≥1.5) and unbraked (<1.5). Results: According to the expiratory flow shape braked breaths were chategorized into early peak expiratory flow, late peak expiratory flow, slow flow, and post-inspiratory hold flow (PiHF). The most braked breaths had lower rates, larger tidal volume but lower minute ventilation, inspiratory airway resistance and respiratory effort, except for the PiHF, which had higher resistance and respiratory effort. The braked pattern predominated during TH, but not during normothermia or in the uncooled infants. Conclusions: We speculate that during TH for HIE low respiratory rates favor neonatal braked breathing to preserve lung volume. Given the generally low respiratory effort, it seems reasonable to leave spontaneous breathing unassisted. However, if the PiHF pattern predominates, ventilatory support may be required.

Automated surgery planning for an obstructed nose by combining computational fluid dynamics with reinforcement learning.

Septoplasty and turbinectomy are among the most common interventions in the field of rhinology. Their constantly debated success rates and the lack of quantitative flow data of the entire nasal airway for planning the surgery necessitate methodological improvement. Thus, physics-based surgery planning is highly desirable. In this work, a novel and accurate method is developed to enhance surgery planning by physical aspects of respiration, i.e., to plan anti-obstructive surgery, for the first time a reinforcement learning algorithm is combined with large-scale computational fluid dynamics simulations. The method is integrated into an automated pipeline based on computed tomography imaging. The proposed surgical intervention is compared to a surgeon's initial plan, or the maximum possible intervention, which allows the quantitative evaluation of the intended surgery. Two criteria are considered: (i) the capability to supply the nasal airway with air expressed by the pressure loss and (ii) the capability to heat incoming air represented by the temperature increase. For a test patient suffering from a deviated septum near the nostrils and a bony spur further downstream, the method recommends surgical interventions exactly at these locations. For equal weights on the two criteria (i) and (ii), the algorithm proposes a slightly weaker correction of the deviated septum at the first location, compared to the surgeon's plan. At the second location, the algorithm proposes to keep the bony spur. For a larger weight on criterion (i), the algorithm tends to widen the nasal passage by removing the bony spur. For a larger weight on criterion (ii), the algorithm's suggestion approaches the pre-surgical state with narrowed channels that favor heat transfer. A second patient is investigated that suffers from enlarged turbinates in the left nasal passage. For equal weights on the two criteria (i) and (ii), the algorithm proposes a nearly complete removal of the inferior turbinate, and a moderate reduction of the middle turbinate. An increased weight on criterion (i) leads to an additional reduction of the middle turbinate, and a larger weight on criterion (ii) yields a solution with only slight reductions of both turbinates, i.e., focusing on a sufficient heat exchange between incoming air and the air-nose interface. The proposed method has the potential to improve the success rates of the aforementioned surgeries and can be extended to further biomedical flows.

A preliminary study of dynamic interactive simulation and computational CT scan of the ideal alveolus model.

BACKGROUND: While the development of CT imaging technique has brought cognition of in vivo organs, the resolution of CT images and their static characteristics have gradually become barriers of microscopic tissue research. PURPOSE: Previous research used the finite element method to study the airflow and gas exchange in the alveolus and acinar to show the fate of inhaled aerosols and studied the diffusive, convective, and sedimentation mechanisms. Our study combines these techniques with CT scan simulation to study the mechanisms of respiratory movement and its imaging appearance. METHODS: We use 3D fluid-structure interaction simulation to study the movement of an ideal alveolus under regular and forced breathing situations and ill alveoli with different tissue elasticities. Additionally, we use the Monte Carlo algorithm within the OpenGATE platform to simulate the computational CT images of the dynamic process with different designated resolutions. The resolutions show the relationship between the kinematic model of the human alveolus and its imaging appearance. RESULTS: The results show that the alveolus and the wall thickness can be seen with an image resolution smaller than 15.6 µm. With ordinary CT resolution, the alveolus is expressed with four voxels. CONCLUSIONS: This is a preliminary study concerning the imaging appearance of the dynamic alveolus model. This technique will be used to study the imaging appearance of the dynamic bronchial tree and the lung lobe models in the future.

Advancements in Home-Based Devices for Detecting Obstructive Sleep Apnea: A Comprehensive Study.

Obstructive Sleep Apnea (OSA) is a respiratory disorder characterized by frequent breathing pauses during sleep. The apnea-hypopnea index is a measure used to assess the severity of sleep apnea and the hourly rate of respiratory events. Despite numerous commercial devices available for apnea diagnosis and early detection, accessibility remains challenging for the general population, leading to lengthy wait times in sleep clinics. Consequently, research on monitoring and predicting OSA has surged. This comprehensive paper reviews devices, emphasizing distinctions among representative apnea devices and technologies for home detection of OSA. The collected articles are analyzed to present a clear discussion. Each article is evaluated according to diagnostic elements, the implemented automation level, and the derived level of evidence and quality rating. The findings indicate that the critical variables for monitoring sleep behavior include oxygen saturation (oximetry), body position, respiratory effort, and respiratory flow. Also, the prevalent trend is the development of level IV devices, measuring one or two signals and supported by prediction software. Noteworthy methods showcasing optimal results involve neural networks, deep learning, and regression modeling, achieving an accuracy of approximately 99%.

Analysis of Upper Airway Flow Dynamics in Robin Sequence Infants Using 4-D Computed Tomography and Computational Fluid Dynamics.

Robin Sequence (RS) is a potentially fatal craniofacial condition characterized by undersized jaw, posteriorly displaced tongue, and resultant upper airway obstruction (UAO). Accurate assessment of UAO severity is crucial for management and diagnosis of RS, yet current evaluation modalities have significant limitations and no quantitative measures of airway resistance exist. In this study, we combine 4-dimensional computed tomography and computational fluid dynamics (CFD) to assess, for the first time, UAO severity using fluid dynamic metrics in RS patients. Dramatic intrapopulation differences are found, with the ratio between most and least severe patients in breathing resistance, energy loss, and peak velocity equal to 40:1, 20:1, and 6:1, respectively. Analysis of local airflow dynamics characterized patients as presenting with primary obstructions either at the location of the tongue base, or at the larynx, with tongue base obstructions resulting in a more energetic stenotic jet and greater breathing resistance. Finally, CFD-derived flow metrics are found to correlate with the level of clinical respiratory support. Our results highlight the large intrapopulation variability, both in quantitative metrics of UAO severity (resistance, energy loss, velocity) and in the location and intensity of stenotic jets for RS patients. These results suggest that computed airflow metrics may significantly improve our understanding of UAO and its management in RS.

Wearable Piezoelectric Airflow Transducers for Human Respiratory and Metabolic Monitoring.

Despite the importance of respiration and metabolism measurement in daily life, they are not widely available to ordinary people because of sophisticated and expensive equipment. Here, we first report a straightforward and economical approach to monitoring respiratory function and metabolic rate using a wearable piezoelectric airflow transducer (WPAT). A self-shielded bend sensor is designed by sticking two uniaxially drawn piezoelectric poly l-lactic acid films with different cutting angles, and then the bend sensor is mounted on one end of a plastic tube to engineer the WPAT. The airflow sensing principle of the WPAT is theoretically determined through finite element simulation, and the WPAT is calibrated with a pulse calibration method. We prove that the WPAT has similar accuracy (correlation coefficient >0.99) to a pneumotachometer in respiratory flow and lung volume assessment. We demonstrate metabolism measurement using the WPAT and the relationship between minute volume and metabolic rates via human wear trials. The mean difference of measured metabolic rates between the WPAT and a Biopac indirect calorimeter is 0.015 kcal/min, which shows comparable performance. Significantly, unlike the Biopac indirect calorimeter with an airflow sensor, an oxygen gas sensor, and a carbon dioxide gas sensor, we merely use the simple-structured WPAT to measure metabolism. Thus, we expect the WPAT technology to provide a precise, convenient, and cost-effective respiratory and metabolic monitoring solution for next-generation medical home care applications and wearable healthcare systems.

Evaluation of respiratory function among homemakers exposed to indoor air pollution.

Indoor air contamination is a condition that can increase cardiovascular and respiratory mortality in the present-day population. Utilizing cooking exhaust in working environments, pollutants such as Polycyclic aromatic hydrocarbons (PAHs), incense sticks, cooking in fuel and kindling oven in the kitchen, and tobacco smoke are the significant reasons for indoor air contamination. The point of this study is to make mindfulness among homemakers presented to indoor air contamination. A spellbinding cross-sectional review including 100 homemaker female subjects in the age of 40-50 know about indoor air contamination. An overview was directed among 100 home creators in regard to indoor air contamination to make mindfulness. The strategy for testing done is basic arbitrary inspecting. The aftereffects of the current review showed that respondents were greatly presented to the indoor air contamination and created side effects connected with it and generally respondents in the age gathering of 40-50 years had encountered more exhaustion, dry bothersome skin, copying and aggravation of the eyes and stodgy nose, and affiliation was measurably huge. This finding revealed the indoor air toxins that can be considered to assume a part underway to infections like asthma, and so forth.

Automatic Separation of Respiratory Flow from Motion in Thermal Videos for Infant Apnea Detection.

Both Respiratory Flow (RF) and Respiratory Motion (RM) are visible in thermal recordings of infants. Monitoring these two signals usually requires landmark detection for the selection of a region of interest. Other approaches combine respiratory signals coming from both RF and RM, obtaining a Mixed Respiratory (MR) signal. The detection and classification of apneas, particularly common in preterm infants with low birth weight, would benefit from monitoring both RF and RM, or MR, signals. Therefore, we propose in this work an automatic RF pixel detector not based on facial/body landmarks. The method is based on the property of RF pixels in thermal videos, which are in areas with a smooth circular gradient. We defined 5 features combined with the use of a bank of Gabor filters that together allow selection of the RF pixels. The algorithm was tested on thermal recordings of 9 infants amounting to a total of 132 min acquired in a neonatal ward. On average the percentage of correctly identified RF pixels was 84%. Obstructive Apneas (OAs) were simulated as a proof of concept to prove the advantage in monitoring the RF signal compared to the MR signal. The sensitivity in the simulated OA detection improved for the RF signal reaching 73% against the 23% of the MR signal. Overall, the method yielded promising results, although the positioning and number of cameras used could be further optimized for optimal RF visibility.

Analysis of flow field and turbulence predictions in a lung model applying RANS and implications for particle deposition.

Airflow and aerosol deposition in the human airways are important aspects for applications such as pulmonary drug delivery and human exposure to aerosol pollutants. Numerical simulations are widely used nowadays to shed light in airflow features and particle deposition patterns inside the airways. For that purpose, the Euler/Lagrange approach is adopted for predicting flow field and particle deposition through point-particle tracking. Steady-state RANS (Reynolds-averaged Navier-Stokes) computations of flow evolution in an extended lung model applying different turbulence models were conducted and compared to measurements as well as high resolution LES (large-eddy simulations) for several flow rates. In addition, various inlet boundary conditions were considered and their influence on the predicted flow field was analysed. The results showed that the mean velocity field was simulated reasonably well, however, turbulence intensity was completely under-predicted by two-equation turbulence models. Only a Reynolds-stress model (RSM) was able predicting a turbulence level comparable to the measurements and the high resolution LES. Remarkable reductions in wall deposition were observed when wall effects were accounted for in the drag and lift force expressions. Naturally, turbulence is an essential contribution to particle deposition and it is well known that two-equation turbulence models considerably over-predict deposition due to the spurious drift effect. A full correction of this error is only possible in connection with a Reynolds-stress turbulence model whereby the predicted deposition in dependence of particle diameter yielded better agreement to the LES predictions. Specifically, with the RSM larger deposition is predicted for smaller particles and lower deposition fraction for larger particles compared to LES. The local deposition fraction along the lung model was numerically predicted with the same trend as found from the measurements, however the values in the middle region of the lung model were found to be somewhat larger.

Lung function assessment in the Pacific walrus (Odobenus rosmarus divergens) while resting on land and submerged in water.

In the present study, we examined lung function in healthy resting adult (born in 2003) Pacific walruses (Odobenus rosmarus divergens) by measuring respiratory flow ([Formula: see text]) using a custom-made pneumotachometer. Three female walruses (670-1025 kg) voluntarily participated in spirometry trials while spontaneously breathing on land (sitting and lying down in sternal recumbency) and floating in water. While sitting, two walruses performed active respiratory efforts, and one animal participated in lung compliance measurements. For spontaneous breaths, [Formula: see text] was lower when walruses were lying down (e.g. expiration: 7.1±1.2 l s-1) as compared with in water (9.9±1.4 l s-1), while tidal volume (VT, 11.5±4.6 l), breath duration (4.6±1.4 s) and respiratory frequency (7.6±2.2 breaths min-1) remained the same. The measured VT and specific dynamic lung compliance (0.32±0.07 cmH2O-1) for spontaneous breaths were higher than those estimated for similarly sized terrestrial mammals. VT increased with body mass (allometric mass-exponent=1.29) and ranged from 3% to 43% of the estimated total lung capacity (TLCest) for spontaneous breaths. When normalized for TLCest, the maximal expiratory [Formula: see text] ([Formula: see text]exp) was higher than that estimated in phocids, but lower than that reported in cetaceans and the California sea lion. [Formula: see text]exp was maintained over all lung volumes during spontaneous and active respiratory manoeuvres. We conclude that location (water or land) affects lung function in the walrus and should be considered when studying respiratory physiology in semi-aquatic marine mammals.

Reliability of voluntary cough assessments using respiratory flow waveform.

[Purpose] Voluntary cough can be assessed by recording flow waves. The purpose of this study was to examine the reliability of the measurements of respiratory flow waveforms, using equipment that recorded flow waves during cough. [Participants and Methods] Twenty healthy participants were recruited for this study. They underwent spirometry on them and, subsequently, their flow waves during single and consecutive voluntary cough tasks in the sitting position were recorded. The intra-class correlation coefficient was used to assess the intra-rater and inter-rater reliabilities for the voluntary cough data. [Results] The intra-class correlation coefficients were 0.6 to 0.8 for 'intra-rater reliability' and higher than 0.9 for 'inter-rater reliability', for single and consecutive cough tasks. The first assessment of cough peak flow was significantly higher than the second, during consecutive cough tasks. Similarly, the first assessment of cough volume acceleration was significantly higher than the second. [Conclusion] Our results demonstrated high intra-rater and inter-rater reliabilities for single and consecutive cough tasks. Following additional procedures and valuations, including the storage of data and standard range decisions, this method of cough assessment will be applied to patients with reduced cough function.

A pilot study of minimum operational flow for loose-fitting powered air-purifying respirators used in healthcare cleaning services.

The objective of this pilot study was to determine the minimum operational flow for loose-fitting powered air-purifying respirators (PAPR) used in healthcare cleaning services. An innovative respiratory flow recording device was worn by nine healthcare workers to obtain the minute volume (MV, L/min), mean inhalation flow (MIF, L/min), and peak inhalation flow (PIF, L/min) while performing "isolation unit work" (cleaning and disinfecting) of a patient room within 30 min. The MV and PIF were compared with the theoretical values obtained from an empirical formula. The correlations of MV, MIF, and PIF with subjects' age, weight, height, body surface area (ADu), and body mass index (BMI) were analyzed. The average MV, MIF, and PIF were 33, 74, and 107 L/min, with maximal airflow rates of 41, 97, and 145 L/min, respectively, which are all below the current 170 L/min minimum operational flow for NIOSH certified loose-fitting PAPRs.

[Integration of Micro Sensors with Mobile Devices for Monitoring Vital Signs of Sleep Apnea Patients].

This paper demonstrates a BSN-based portable monitor integrating micro sensors with mobile devices for monitoring and diagnosing obstructive sleep apnea syndrome (OSAS) at home. The system uses a micro hot-film flow sensor to detect respiratory flow, uses tri-axis micro accelerometer to detect body posture and motion intensity, and uses a micro photoelectric sensor to detect oxygen saturation of blood. The real-time vital signs are detected and transmitted wirelessly to a mobile device. The transmitted data are processed and analyzed in the mobile device and can be further transmitted to a remote medical center and physicians through mobile cellular networks or Internet for comprehensively analyzing, assessing, and diagnosing to the diseases.

Integration of Micro Sensors with Mobile Devices for Monitoring Vital Signs of Sleep Apnea Patients / 中国医疗器械杂志

This paper demonstrates a BSN-based portable monitor integrating micro sensors with mobile devices for monitoring and diagnosing obstructive sleep apnea syndrome (OSAS) at home. The system uses a micro hot-film flow sensor to detect respiratory flow, uses tri-axis micro accelerometer to detect body posture and motion intensity, and uses a micro photoelectric sensor to detect oxygen saturation of blood. The real-time vital signs are detected and transmitted wirelessly to a mobile device. The transmitted data are processed and analyzed in the mobile device and can be further transmitted to a remote medical center and physicians through mobile cellular networks or Internet for comprehensively analyzing, assessing, and diagnosing to the diseases.

A flow-leak correction algorithm for pneumotachographic work-of-breathing measurement during high-flow nasal cannula oxygen therapy.

Measuring work of breathing (WOB) is an intricate task during high-flow nasal cannula (HFNC) therapy because the continuous unidirectional flow toward the patient makes pneumotachography technically difficult to use. We implemented a new method for measuring WOB based on a differential pneumotachography (DP) system, equipped with one pneumotachograph inserted in the HFNC circuit and another connected to a monitoring facemask, combined with a leak correction algorithm (LCA) that corrects flow measurement errors arising from leakage around the monitoring facemask. To test this system, we used a mechanical lung model that provided data to compare LCA-corrected respiratory flow, volume and time values with effective values obtained with a third pneumotachograph used instead of the LCA to measure mask flow leaks directly. Effective and corrected volume and time data showed high agreement (Bland-Altman plots) even at the highest leak. Studies on two healthy adult volunteers confirmed that corrected respiratory flow combined with esophageal pressure measurements can accurately determine WOB (relative error < 1%). We conclude that during HFNC therapy, a DP system combined with a facemask and an algorithm that corrects errors due to flow leakages allows pneumotachography to measure reliably the respiratory flow and volume data needed for calculating WOB.

Correlation between acoustic rhinometry, computed rhinomanometry and cone-beam computed tomography in mouth breathers with transverse maxillary deficiency / Correlação entre rinometria acústica, rinomanometria computorizada e tomografia computadorizada de feixe cônico em respiradores bucais com atresia maxilar

Abstract Introduction To provide clinical information and diagnosis in mouth breathers with transverse maxillary deficiency with posterior crossbite, numerous exams can be performed; however, the correlation among these exams remains unclear. Objective To evaluate the correlation between acoustic rhinometry, computed rhinomanometry, and cone-beam computed tomography in mouth breathers with transverse maxillary deficiency. Methods A cross-sectional study was conducted in 30 mouth breathers with transverse maxillary deficiency (7-13 y.o.) patients with posterior crossbite. The examinations assessed: (i) acoustic rhinometry: nasal volumes (0-5 cm and 2-5 cm) and minimum cross-sectional areas 1 and 2 of nasal cavity; (ii) computed rhinomanometry: flow and average inspiratory and expiratory resistance; (iii) cone-beam computed tomography: coronal section on the head of inferior turbinate (Widths 1 and 2), middle turbinate (Widths 3 and 4) and maxilla levels (Width 5). Acoustic rhinometry and computed rhinomanometry were evaluated before and after administration of vasoconstrictor. Results were compared by Spearman's correlation and Mann-Whitney tests (α = 0.05). Results Positive correlations were observed between: (i) flow evaluated before administration of vasoconstrictor and Width 4 (Rho = 0.380) and Width 5 (Rho = 0.371); (ii) Width 2 and minimum cross-sectional areas 1 evaluated before administration of vasoconstrictor (Rho = 0.380); (iii) flow evaluated before administration of vasoconstrictor and nasal volumes of 0-5 cm (Rho = 0.421), nasal volumes of 2-5 cm (Rho = 0.393) and minimum cross-sectional areas 1 (Rho = 0.375); (iv) Width 4 and nasal volumes of 0-5 cm evaluated before administration of vasoconstrictor (Rho = 0.376), nasal volumes of 2-5 cm evaluated before administration of vasoconstrictor (Rho = 0.376), minimum cross-sectional areas 1 evaluated before administration of vasoconstrictor (Rho = 0.410) and minimum cross-sectional areas 1 after administration of vasoconstrictor (Rho = 0.426); (v) Width 5 and Width 1 (Rho = 0.542), Width 2 (Rho = 0.411), and Width 4 (Rho = 0.429). Negative correlations were observed between: (i) Width 4 and average inspiratory resistance (Rho = −0.385); (ii) average inspiratory resistance evaluated before administration of vasoconstrictor and nasal volumes of 0-5 cm (Rho = −0.382), and average expiratory resistance evaluated before administration of vasoconstrictor and minimum cross-sectional areas 1 (Rho = −0.362). Conclusion There were correlations between acoustic rhinometry, computed rhinomanometry, and cone-beam computed tomography in mouth breathers with transverse maxillary deficiency.

Resumo Introdução Numerosos exames podem ser realizados para fornecer informações clínicas e diagnósticas em respiradores bucais com atresia maxilar e mordida cruzada posterior, entretanto a correlação entre esses exames ainda é incerta. Objetivo Avaliar a correlação entre rinometria acústica, rinomanometria computadorizada e tomografia computadorizada por feixe cônico em respiradores bucais com atresia maxilar. Método Um estudo de corte transversal foi realizado em 30 respiradores bucais com atresia maxilar (7-13 anos) com mordida cruzada posterior. Os exames avaliados foram: (i) rinomanometria acústica: volumes nasais (0-5 cm e 2-5 cm) e áreas mínimas de corte transversal 1 e 2 da cavidade nasal; (ii) rinomanometria computadorizada: fluxo nasal e resistências médias inspiratórias e expiratórias; (iii) tomografia computadorizada por feixe cônico: corte coronal na cabeça da concha inferior (larguras 1 e 2), concha média (larguras 3 e 4) e na maxila (Largura 5). Rinomanometria acústica e rinomanometria computadorizada foram avaliadas antes e depois da administração de vasoconstritor. Os resultados foram comparados pelo teste de correlação de Spearman e pelo teste de Mann-Whitney (α = 0,05). Resultados Foram encontradas correlações positivas entre: (i) fluxo antes da administração de vasoconstritor e largura 4 (Rho = 0,380) e largura 5 (Rho = 0,371); (ii) largura 2 e área mínima de corte transversal 1 antes da administração de vasoconstritor (Rho = 0,380); (iii) fluxo antes da administração de vasoconstritor e volumes nasais de 0-5 cm (Rho = 0,421), 2-5 cm (Rho = 0,393) e área mínima de corte transversal 1 (Rho = 0,375); (iv) largura 4 e volume nasal de 0-5 cm antes da administração do vasoconstritor (Rho = 0,376), volume nasal de 2-5 cm antes do uso de vasoconstritor (Rho = 0,376), áreas mínimas de corte transversal 1 antes da administração de vasoconstritor (Rho = 0,410) e áreas mínimas de corte transversal 1 após o uso do vasoconstritor (Rho = 0,426); (v) largura 5 e largura 1 (Rho = 0,542), largura 2 (Rho = 0,411) e largura 4 (Rho = 0,429). Foram encontradas correlações negativas: (i) largura 4 e resistência inspiratória média (Rho = −0,385); (ii) resistência inspiratória média antes da administração de vasoconstritor e volume de 0-5 cm (Rho = −0,382) e resistência expiratória média antes da administração de vasoconstritor e área mínima de corte transversal 1 (Rho = −0,362). Conclusão Correlações foram encontradas entre a rinometria acústica, a rinomanometria computadorizada e a tomografia computadorizada de feixe cônico em respiradores bucais com atresia maxilar.

Phthalate esters on urban airborne particles: Levels in PM10 and PM2.5 from Mexico City and theoretical assessment of lung exposure.

Endocrine disrupting chemicals (EDCs) from the environment are associated with reproductive abnormalities (i.e. decreased sperm concentration; increased endometriosis) and alterations of the cardiovascular system (i.e. increased blood pressure and risk of coronary disease). Some phthalates esters have been identified as EDCs, for which inhalation is considered as one of the routes of exposure. However, only little is known regarding inhalational exposure to EDCs via urban airborne particles. In the present study, we report the monthly concentration of 8 phthalate esters measured in PM10 and PM2.5 collected and recovered during 7 months in a highly populated area of Mexico City. Using the levels of PM10 and PM2.5 reported by the automatized network of environmental monitoring of Mexico City for the sampling site, we estimated exposure levels for people of different ages and gender. Two endocrine disrupting compounds, the phthalate esters DEHP and DnBP, were found on the particles in higher concentrations during the warmer months of the year. The highest concentration was reported for DEHP (229.7µg/g of particles) in PM2.5 collected in May 2013. After calculations of the DEHP concentration in the atmosphere, and using the respiratory flow rate, we determined males were potentially exposed to larger quantities of DEHP, reaching up to 18ng/8h in April 2013. Despite the concentrations of phthalates seem to be rather small, a comprehensive characterization of its presence is necessary in order to evaluate the overall exposure to these compounds, providing a clear view of exposure on children, adolescents and pregnant women.

Assessment of Two Personal Breathing Recording Devices in a Simulated Healthcare Environment.

BACKGROUND: In the field of respiratory protection for healthcare workers (HCWs), few data are available on respiratory airflow rate when HCWs are performing their work activities. The objective of this study was to assess the performance of two wearable breathing recording devices in a simulated healthcare environment. METHODS: Breathing recording devices from two different manufactures "A" and "B" were assessed using 15 subjects while performing a series of simulated healthcare work activities (patient assessment; vitals; IV treatment; changing linen; carrying weight while walking; normal breathing while standing). The minute volume (MV, L/min), mean inhalation flow (MIF, L/min), peak inhalation flow (PIF, L/min), breathing frequency (f, breaths/min), and tidal volume (TV, L/min) measured by each device were analyzed. Bland-Altman method was applied to explore the variability of devices A and B. Duncan's multiple range test was used to investigate the differences among activity-specific inspiratory flow rates. RESULTS: The average MV, MIF and PIF reported by device A were 23, 54, and 82 L/min with 95% upper confidence intervals (CIs) of 25, 60 and 92 L/min; the mean differences of MV, MIF and PIF presented by the two units of device A were 0.9, 1.3, and 2.8 L/min, respectively. The average values and mean differences of MV, MIF and PIF found with device B were significantly higher than device A (P<0.05), showing a high variability. During non-speech activities, the PIF/MV and MIF/MV ratios were >3.14 and >2, while with speech, the ratios increased to >6 and >3. The f during speech (15 breaths/min) was significantly lower than non-speech activities (20-25 breaths/min). Among different simulated work activities, the PIF of "patient assessment" was the highest. CONCLUSIONS: This study demonstrated a novel approach to characterize respiratory flow for healthcare workers using an innovative wearable flow recording device. Data from this investigation could be useful in the development of future respirator test standards.

Respiratory function and mechanics in pinnipeds and cetaceans.

In this Review, we focus on the functional properties of the respiratory system of pinnipeds and cetaceans, and briefly summarize the underlying anatomy; in doing so, we provide an overview of what is currently known about their respiratory physiology and mechanics. While exposure to high pressure is a common challenge among breath-hold divers, there is a large variation in respiratory anatomy, function and capacity between species - how are these traits adapted to allow the animals to withstand the physiological challenges faced during dives? The ultra-deep diving feats of some marine mammals defy our current understanding of respiratory physiology and lung mechanics. These animals cope daily with lung compression, alveolar collapse, transient hyperoxia and extreme hypoxia. By improving our understanding of respiratory physiology under these conditions, we will be better able to define the physiological constraints imposed on these animals, and how these limitations may affect the survival of marine mammals in a changing environment. Many of the respiratory traits to survive exposure to an extreme environment may inspire novel treatments for a variety of respiratory problems in humans.

The influence of a low air pressure environment on human metabolic rate during short-term (< 2 h) exposures.

Passengers in aircraft cabins are exposed to low-pressure environments. One of the missing links in the research on thermal comfort under cabin conditions is the influence of low air pressure on the metabolic rate. In this research, we simulated the cabin pressure regime in a chamber in which the pressure level could be controlled. Three pressure levels (101/85/70 kPa) were tested to investigate how metabolic rate changed at different pressure levels. The results show that as pressure decreased, the respiratory flow rate (RFR) at standard condition (STPD: 0°C, 101 kPa) significantly decreased. Yet the oxygen (O2 ) consumption and carbon dioxide (CO2 ) production significantly increased, as reflected in the larger concentration difference between inhaled and exhaled air. A significant increase in the respiratory quotient (RQ) was also observed. For metabolic rate, no significant increase (P > 0.05) was detected when pressure decreased from 101 kPa to 85 kPa; however, the increase associated with a pressure decrease from 85 kPa to 70kPa was significant (P < 0.05). Empirical equations describing the above parameters are provided, which can be helpful for thermal comfort assessment in short-haul flights.