Subjects Breathing Research Articles

Effects of Positive Expiratory Pressure Device on Gas Exchange, Atelectasis, Hemodynamics, and Dyspnea in Spontaneously Breathing Critically Ill Subjects.

EzPAP Positive Airway Pressure System (EzPAP) is a noninvasive positive expiratory pressure (PEP) device designed to promote lung expansion. The aim of this study was to evaluate the effects of PEP on gas exchange. Secondary objectives included assessing the early effects of PEP on radiological atelectasis score (RAS), hemodynamics, and dyspnea. These outcomes were compared between spontaneously breathing subjects with and without tracheostomy. This observational single-center study was conducted at a university hospital. Inclusion criteria were spontaneously breathing adult subjects with RAS ≥ 2 and a worsened PaO2 /FIO2 . Exclusion criteria included life-threatening conditions, intracranial hypertension, hemodynamic instability, and pneumothorax. Gas-exchange, hemodynamic parameters, and dyspnea measured with the Respiratory Distress Observation Scale (RDOS) were assessed at 3 time points: T0 (before PEP), T1 (immediately after PEP), and T2 (2 h after PEP). RAS was assessed at T0 and 1-week post treatment (T3). Of 213 patients assessed for eligibility, 186 were excluded for various reasons, leaving 27 subjects (19 without and 8 with tracheostomy) enrolled in the study. The median [interquartile range] age was 65 [58-74] y, with 66.7% being male. In the overall sample and in subjects without tracheostomy, PaO2 /FIO2 did not differ significantly between T1 and T0 (P = .52 and P = .54, respectively) or between T2 and T0 (P = .47 and P = .85, respectively). In subjects with tracheostomy, PaO2 /FIO2 was higher at T1 compared to T0 (P = .039) but not between T2 and T0 (P = .58). Arterial PaO2 and hemodynamic parameters remained unchanged in the overall cohort. The RAS improved within 1 week of treatment in the overall cohort (T3 vs T0, P < .001) and in subjects without tracheostomy (T3 vs T0, P = .001). However, PEP therapy did not improve RDOS. In critically ill, spontaneously breathing subjects, PEP therapy significantly improved RAS without affecting hemodynamic stability or respiratory symptoms.

Modeling ventilation of patients with interstitial lung disease at rest and exercise: a bench study

BackgroundThe ventilatory physiopathology of patients with interstitial lung disease (ILD) remains poorly understood. We aimed to personalize a mechanical simulator to model healthy and ILD profiles ventilation, and to evaluate the effect of spontaneous breathing on respiratory mechanics at rest and during exercise.MethodsIn a 2-compartment lung simulator (ASL 5000®), we modeled 1 healthy and 3 ILD profiles, at rest and during exercise, based on physiological data from literature and patients. Measurements were: tidal volume, end-expiratory lung volume, driving pressure, transpulmonary driving pressure, dynamic alveolar strain, mechanical power, and time lag of inspiratory flow between compartments 1 and 2.ResultsHealthy and ILD models were validated: maximum differences between real and simulated tidal volume were 5% (96 ml) and 6% (54 ml) at rest and during exercise respectively, considered clinically negligible. When we simulated lung inhomogeneity (compliance in compartment 1 > compartment 2), tidal volume, end-expiratory lung volume, driving pressure and mechanical power increased in compartment 1 and decreased in compartment 2. Driving transpulmonary pressure and dynamic alveolar strain increased in compartment 2 and decreased in compartment 1. Time lag of inspiratory flow between compartments 1 and 2 was positively correlated with a difference of compliance between compartments (r = 0.98, CI95% (0.9106; 0.9962), p < 0.0001).ConclusionIn this bench study, we personalized a mechanical simulator thatmodels the lung inhomogeneity and spontaneous breathing of healthy subjects and ILD patients at rest and during exercise. Our results suggest that lung inhomogeneity could increase lung vulnerability to volo-atelec-trauma mechanisms in ILD. Further physiological studies are needed to evaluate the impact of this vulnerability on acute or chronic ILD worsening.

Breathlessness, but not breathing instability, varies with posttraumatic stress symptoms in university students.

Obstructive sleep apnea (OSA) is a chronic sleep-related breathing disorder that is highly prevalent in individuals with posttraumatic stress disorder (PTSD). The reason for this high prevalence remains unclear. We hypothesized that breathing instability, one of the key contributors to OSA, may be altered in PTSD and predispose OSA. Healthy participants (214 females, 98 males) aged 17 to 42 (M = 19.92; SD = 2.85) completed online questionnaires measuring PTSD symptomatology, sleep disturbances, and self-reported breathlessness. A subset of these participants (16 females, 14 males) aged 18 to 42 (M = 23.50; SD = 7.18) completed an in-lab breathing instability assessment, whereby they performed a series of 20-second and maximal duration breath-holds. PTSD severity positively predicted subjective perceptions of breathlessness (P < 0.001) but not objective measures of breathing instability, namely ventilation following 20-s breath-holds (P = 0.93) and maximal breath-hold duration (P = 0.41). These results suggest that breathing instability may not be the driving factor behind the high prevalence of OSA in PTSD. Instead, other factors such as a low arousal threshold, elevated ventilatory responses to arousal, or coexisting insomnia may explain the high rates of OSA in PTSD. One explanation for the discrepancy between subjective breathlessness and breathing stability measures relating to PTSD severity may be that hypervigilance and increased anxiety impacted self-perceptions of breathlessness while not altering breathing instability per se.NEW & NOTEWORTHY Obstructive sleep apnea (OSA) is more common in individuals with posttraumatic stress disorder (PTSD) than the general population for unknown reasons. This study assessed one of the key contributors to OSA, respiratory control instability, in young students with a range of posttraumatic stress symptoms. Although individuals with high PTSD symptoms reported increased subjective breathlessness, objectively measured breathing instability was not altered, suggesting respiratory instability is unlikely to increase the risk of OSA in PTSD.

Relationships between capnogram parameters by mainstream and sidestream techniques at different breathing frequencies

Capnography, routinely used in operating rooms and intensive care units, reveals essential information on lung ventilation and ventilation–perfusion matching. Mainstream capnography directly measures CO2 in the breathing circuit for accurate analysis and is considered a reference technique. Sidestream capnography, however, analyzes gas away from the patient leading to potentially less accurate measures. While these methodological differences impact the capnogram indices in mechanically ventilated patients, such assessments during spontaneous breathing are essentially lacking. Accordingly, we aimed to compare mainstream and sidestream capnography in spontaneously breathing subjects, focusing on differences in capnogram shape and dead space indices at various respiratory rates. Simultaneous mainstream and sidestream time and volumetric capnography were performed on spontaneously breathing adults (n = 35). Measurements were performed during controlled low (10/min), medium (12/min), and high (20/min) breathing rates as a challenge. Correlation and Bland–Altman analyses were used to assess trends and agreements between time and volumetric capnography indices obtained by the mainstream and sidestream techniques, including end-tidal CO2 (ETCO2), shape factors reflecting the slopes of phases 2 and 3, and anatomical and physiological dead space fractions. ETCO2 and physiological dead space measured by mainstream and sidestream techniques showed excellent correlations (r > 0.90, p < 0.001 for all breathing rates) and agreements. While strong correlations and moderate agreements were evidenced in the parameters reflecting the late phase of expiration (phase 3 slope and exhaled CO2 volume), these relationships were weaker for indices related to the early phase of expiration (phase 2 slope, anatomical dead space). Changing breathing frequency caused significant alterations in all capnography parameters, which were detectable by both mainstream and sidestream techniques. Sidestream capnography cannot substitute the more accurate mainstream technique for measuring the absolute values of shape factors and ventilation dead space fractions. However, sidestream capnography is also able to detect and track changes in uneven alveolar emptying, ventilation–perfusion matching and ventilation dead space fraction in spontaneously breathing subjects.

Endonasal Thermal Imaging Before and After Nasal Airway Surgery.

Nasal airway surgery is often applied when treatment fails to relieve nasal obstruction. However, surgery that improves airflow does not always alleviate the symptoms of nasal obstruction. The perception of nasal breathing is likely more related to changes in mucosal temperature than the mechanical sensation of flow or pressure. This study aims to measure intranasal mucosal temperature pre-and post-surgery using endonasal thermal imaging, exploring its correlation with subjective nasal breathing and objective airflow measurements. A prospective study of adult patients with nasal obstruction managed with nasal airway surgery was performed. Intranasal mucosal temperatures were determined using the thermal endonasal image of the nasal passage produced by the infrared radiometric thermal camera (FILR VS290). A comparison was made between the mean values of mid-expiration (ExT) and mid-inspiration (InT) temperature data (internal nasal valve, nasal cavity, inferior turbinate, and overall airway [mean value]) and visual analog scale (VAS), Nasal Obstruction Symptom Evaluation (NOSE) scale and nasal airway resistance (NAR) before and after surgery. Seven patients (35.14 ± 16.45 years, 57.14% female) were included. All NOSE, VAS, and NAR improved after surgery (59.29 ± 10.89 vs 17.14 ± 14.64; P < .001, 64.50 ± 26.79 vs 18.57 ± 19.99; P < .001, 0.82 ± 0.48 vs 0.34 ± 0.11 Pa/cm3/s; P = .002, respectively). ExT, InT, and the difference between ExT and InT of three areas and overall airway were similar between pre-and post-surgery. No statistically significant correlations were found between intranasal mucosal temperature, VAS, NOSE, and NAR at pre-and post-surgery except for the difference between ExT and InT of overall airway and NOSE pre-operative (Pearson r = 0.57; 95% CI 0.06-1.09; P = .03). Endonasal thermal imaging can assess the intranasal mucosal temperature of a patient. However, more precise imaging of the nasal passages and data acquisition are required to establish mucosal temperature as an objective measure of nasal obstruction before and after nasal airway surgery in a clinical setting.

Electronic Nose Analysis of Exhaled Breath Volatile Organic Compound Profiles during Normoxia, Hypoxia, and Hyperoxia.

This study investigates volatile organic compound (VOC) profiles in the exhaled breath of normal subjects under different oxygenation conditions-normoxia (FiO2 21%), hypoxia (FiO2 11%), and hyperoxia (FiO2 35%)-using an electronic nose (e-nose). We aim to identify significant differences in VOC profiles among the three conditions utilizing principal component analysis (PCA) and canonical discriminant analysis (CDA). Our results indicate distinct VOC patterns corresponding to each oxygenation state, demonstrating the potential of e-nose technology in detecting physiological changes in breath composition (cross-validated accuracy values: FiO2 21% vs. FiO2 11% = 63%, FiO2 11% vs. FiO2 35% = 65%, FiO2 21% vs. FiO2 35% = 71%, and p < 0.05 for all). This research underscores the viability of breathomics in the non-invasive monitoring and diagnostics of various respiratory and systemic conditions.

Phenotyping COVID-19 respiratory failure in spontaneously breathing patients with AI on lung CT-scan

BackgroundAutomated analysis of lung computed tomography (CT) scans may help characterize subphenotypes of acute respiratory illness. We integrated lung CT features measured via deep learning with clinical and laboratory data in spontaneously breathing subjects to enhance the identification of COVID-19 subphenotypes.MethodsThis is a multicenter observational cohort study in spontaneously breathing patients with COVID-19 respiratory failure exposed to early lung CT within 7 days of admission. We explored lung CT images using deep learning approaches to quantitative and qualitative analyses; latent class analysis (LCA) by using clinical, laboratory and lung CT variables; regional differences between subphenotypes following 3D spatial trajectories.ResultsComplete datasets were available in 559 patients. LCA identified two subphenotypes (subphenotype 1 and 2). As compared with subphenotype 2 (n = 403), subphenotype 1 patients (n = 156) were older, had higher inflammatory biomarkers, and were more hypoxemic. Lungs in subphenotype 1 had a higher density gravitational gradient with a greater proportion of consolidated lungs as compared with subphenotype 2. In contrast, subphenotype 2 had a higher density submantellar–hilar gradient with a greater proportion of ground glass opacities as compared with subphenotype 1. Subphenotype 1 showed higher prevalence of comorbidities associated with endothelial dysfunction and higher 90-day mortality than subphenotype 2, even after adjustment for clinically meaningful variables.ConclusionsIntegrating lung-CT data in a LCA allowed us to identify two subphenotypes of COVID-19, with different clinical trajectories. These exploratory findings suggest a role of automated imaging characterization guided by machine learning in subphenotyping patients with respiratory failure.Trial registration: ClinicalTrials.gov Identifier: NCT04395482. Registration date: 19/05/2020.

Breath assessment at with post-tuberculosis patients suffered new coronavirus infection

BACKGROUND: The possibility of mutual aggravation of post-tuberculosis and post-COVID respiratory pathologies requires additional consideration. AIM: To study some subjective breathing parameters at patients with post-tuberculosis pulmonary residual changes after a new coronavirus infection recovering. MATERIALS AND METHODS: The study included two groups: the main group — 14 patients with cured pulmonary tuberculosis, who had recovered from a new coronavirus infection, a comparison group — 52 patients with post-tuberculosis changes non-sick new coronavirus infection who were admitted to the tuberculosis sanatorium “Glukhovskaya” in 2020–2021. The severity of shortness of breath using the Modified Medical Research Council (mMRC) and Borg scales was assessed upon admission to the sanatorium and a month later. Results: The mMRC scale was 1.5 ± 1.4 and 2.1 ± 0.2 and the Borg scale was 1.5 ± 1.4 and 2.9 ± 0.2 before treatment respectively in the main group and the comparison group. According to the mMRC scale initially 14.3 and 11.5% of patients with pulmonary tuberculosis and the comparison group did not complain of shortness of breath and 50% of pulmonary tuberculosis patients and 42.4% of the comparison group defined it as severe. After a month there were 3 or 4 points on the mMRC scale among pulmonary tuberculosis patients. In the comparison group 3-point shortness of breath decreased by 11.2 times most often indicated shortness of breath with 2 score. According to the Borg scale dyspnea was initially assessed as 3 points at 71.5% pulmonary tuberculosis patients. In the comparison group 67.3% patients had grade 3 dyspnea and 11.5% noted 4–6 grade shortness of breath. After a month the proportion of patients with mild shortness of breath at the pulmonary tuberculosis and comparison groups increased by 4.5 and 3.3 times, respectively, and the frequency of 3-grade shortness of breath decreased by 5 and 3.9 times. CONCLUSIONS: Major post-tuberculosis changes, smoking and chronic obstructive pulmonary disease determine the severity of breathing discomfort to a greater extent than the experience of new coronavirus infection but rehabilitation treatment are leveled out these differences. It is advisable to study the state of the respiratory system at patients cured of pulmonary tuberculosis.

The Alar Extension Graft Technique for the Treatment of External Nasal Valve Collapse: Preliminary Results of a Single-Centre Prospective Analysis.

The aim of this study is to describe the efficacy of the alar extension graft for the correction of external nasal valve collapse and to evaluate the functional and aesthetic results. The study included 51 patients who underwent alar extension grafting for external nasal valve collapse. Pre- and post-operative rhinomanometry was performed before and after surgery. NOSE and SNOT 20 questionnaires were completed before and 9 months after surgery. Patients were also asked about their post-operative satisfaction. 90% of patients were subjectively satisfied with the post-operative improvement in nasal breathing. There was a significant improvement in the values of the pre- and post-operative NOSE and SNOT 20 questionnaire scores. Rhinomanometry showed increased nasal flow with a statistically significant difference between pre- and post-operative results. The alar extension graft has been proved to be effective and reliable in the surgical treatment of external nasal valve collapse, improving the patients' objective and subjective breathing with good functional and aesthetic results. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Does the Addition of Oral Sampling Improve Waveform Capnography When Compared to Traditional Nasal Sampling in Open-Airway Patients?

BackgroundEnd-tidal carbon dioxide (EtCO2) is an invaluable anesthesia measure due to minimal delay in monitoring ventilation. Oral and Maxillofacial Surgery (OMS) presents special challenges because oral exhalations are not sampled effectively via nasal cannula normally used to avoid interfering with procedures. PurposeThe purpose of the study was to compare EtCO2 waveforms obtained in subjects using nasal monitoring and combined nasal and oral monitoring under simulated ventilatory conditions. Study design, setting, sampleA single-blinded, randomized crossover controlled study was conducted at the University of Illinois Chicago with healthy volunteers, who were blinded to the monitoring system used. Inclusion criteria required subjects be >18 years of age, be consentable and English-speaking. Exclusion criteria required no airway abnormalities, no edentulism, no conditions that preclude undergoing an OMS procedure under sedation. Predictor variableThe primary predictor variable was the EtCO2 monitoring system: nasal with a standard nasal cannula, and combined with a nasal cannula and oral device. The secondary predictor variable evaluated three ventilatory states (nasal breathing, oral breathing, apnea) in each arm, standardizing by maintaining consistent breath counts across observation periods. Main outcome variableThe main outcome variable was the number of waveforms recorded over 30 seconds for nasal and combined monitoring. Each recording was standardized by dividing it by the baseline waveforms and multiplying by 20. Higher values, closer to baseline, were considered more accurate depictions of ventilation. CovariatesCovariates were body mass index (BMI), age, sex, Mallampati score, and breathing method. AnalysesANOVA, ANCOVA, and MANOVA were performed. P-value<0.05 was considered statistically significant. ResultsThe sample included 25 subjects (18 male, 7 female) with mean age 29.9+7.98 years and BMI 23.9+3.51 kg/m2. Combined sampling detected more waveforms during nasal and oral breathing (p<0.001). Higher BMI correlated with reduced waveform capture during nasal sampling in oral breathing (p=0.013). Combined sampling detected more waveforms during nasal breathing (p=0.005) in subjects with BMI < 23.5 kg/m2. Mallampati score correlated with increased waveforms during nasal breathing. Conclusions and RelevanceOral EtCO2 sampling may improve accuracy of capnography waveform capture. Further clinical studies in sedated subjects undergoing OMS procedures are needed.

Comparison of 2D and 3D oxygen-enhanced MRI of the placenta.

Oxygen-Enhanced Magnetic Resonance Imaging (OE-MRI) of the human placenta is potentially a sensitive marker of in vivo oxygenation. This methodological study shows that full coverage of the placenta is possible using 3D mapping of the change in longitudinal relaxation rate (ΔR1), in a group of healthy pregnant subjects breathing elevated levels of oxygen. Twelve pregnant subjects underwent a comparison of 2D and 3D OE-MRI. ΔR1 was mapped for a single 2D slice (ss-2D), a single matched-slice from the 3D volume (ss-3D) and the full 3D volume (vol-3D). The group-average median ΔR1 values for ss-3D (0.023 s-1) and vol-3D (0.022 s-1) do not differ significantly from ss-2D (0.020 s-1), when compared using a two-tailed paired t-test (ss-3D (p = 0.58) and vol-3D (p = 0.70)). However, median baseline T1 (T1b) for ss-2D was higher (1603 ms) than T1b for ss-3D (1540 ms, p = 0.07) and significantly higher than vol-3D (1515 ms, p = 0.02), when compared using a two-tailed paired t-test. In contrast with previous studies, no correlation of median ΔR1 with gestation age at scan for the normal group (N = 10) was observed for ss-2D, likely due to the smaller gestational range. Full volume OE-MRI maps reveal sensitivity to changes in ΔR1, with some participants showing an enhanced gradient in the intermediate space between the fetal and maternal sides of the placenta in the 3D data. This study shows that it is feasible to acquire whole placental volume OE-MRI data in women with healthy pregnancy.

Comparing two MRI methods to assess fundamental sex differences in resting cerebral blood flow

Background: Cerebral blood flow (CBF) is a critical measurement for understanding healthy brain physiology prior to aging or neurologic diseases. Patterns of stroke and neurologic pathologies are often sex-specific. Therefore, it is important to understand basic sex differences in CBF, which are often associated with poor brain outcomes. Furthermore, prior literature examining sex differences in CBF is confounded by age, comorbidities, medications, lack of control of menstrual cycle and/or hormonal contraceptive use, and methodological discrepancies. The objective of this study was to compare two different magnetic resonance imaging (MRI) methods of quantifying CBF in young adults while controlling for the aforementioned confounding factors. We hypothesized that females would display higher CBF than males, and that there would be a high reliability between Arterial Spin Labeling (ASL) and 4D Flow MRI. Methods: 30 males and 26 females (23 ± 4yr) were studied on a single MRI (3T) visit. Subjects were fasted 8 hours and withheld caffeine, exercise, and NSAIDs for at least 24 hours. Females were not taking hormonal contraception and were studied on days 1-7 of the menstrual cycle. Microvascular CBF (mL/100g/min) was assessed via pseudo-continuous ASL (pcASL) while 4D Flow MRI acquired with Phase Contrast Vastly undersampled Isotropic Projection Reconstruction (PC VIPR) yielded macrovascular flow via the larger cerebral arteries, summing the internal carotid arteries and basilar artery for total CBF (mL/min). A T1-weighted MRI scan was used to provide brain volumes, allowing CBF from PC VIPR to be normalized and compared to ASL (mL/100g/min). The scans were taken consecutively, with subjects breathing normoxic gas while hemodynamics and end tidal CO2 were monitored. Regression analysis was used to determine reliability of two measures to test a sex difference in CBF. Results: Linear regression analysis demonstrated reliability between measurements of resting CBF via ASL and PC VIPR (p&lt;0.001, R2=0.621). However, ASL measured significantly higher blood flows than PC VIPR in females (63.40 ± 8.55 vs. 56.47 ± 8.48 mL/100g/min, p&lt;0.001) while male subjects had similar flows measured by both methods (45.75 ± 9.39 vs. 46.69 ± 8.19 mL/100g/min, p=0.464). Females displayed an increase in resting CBF compared to males, being 27.8% and 17.3% higher in the ASL and PC VIPR flow measurements (both p&lt;0.001), respectively. Conclusions: These results demonstrate that ASL and PC VIPR CBF display a strong correlation, and that females have greater resting CBF compared to males that is detected by both MRI methods of quantification. However, ASL resulted in greater flow measurements in females, resulting in larger differences being observed (27.8% versus 17.3%). This discrepancy in CBF quantification warrants further investigation to determine the optimal mode of CBF measurement and comparison. Funding by NIH (HL150361). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Ammonia measurement in human breath of subjects with Helicobacter pylori using photoacoustic spectroscopy.

Helicobacter pylori (H. pylori) is a type of bacteria that infects the stomach. The detection of H. pylori is an essential part of current clinical practices because this disease can cause peptic ulcers, chronic inflammation of the stomach lining but also stomach cancer. Helicobacter pylori has a naturally occurring enzyme that hydrolyzes urea into ammonium carbonate called urease. Many methods exist for the detection of H. pylori infection, but an innovative approach is to detect the ammonia in the breath (ABT, Ammonia Breath Test). In this research study, using photoacoustic spectroscopy method, the ammonia concentration in the breathing zone of people with H. pylori were measured and were compared with ammonia concentration from the respiration of healthy people. From the ABT determinations of this study, the ammonia was established to be increased with 498 ppb at people with H. pylori when we compare with ABT of healthy people.

Effective volume of rebreathed air during breathing with facepieces increases with protection class and decreases with ambient airflow.

Wearing facepieces is discussed in the context of increasing the volume of rebreathed air. We hypothesized that rebreathed air volume increases with increasing filtering facepiece (FFP) class and that persons breathing via facepieces compensate for the additional dead-space. We have determined the effective amount of rebreathed air for a surgical masks and FFP2 and FFP3 respirators in a physical model and determined tidal volumes, breathing frequency, blood oxygen saturation, and transcutaneously measured blood carbon dioxide partial pressure (PCO2) in lung-healthy subjects breathing without and with facepieces at rest and during exercising on a recumbent ergometer. Rebreathed air volume increased with the facepieces' protection class and with increasing inspiration volume by 45 ± 2 ml to 247 ± 1 ml. Ambient airflow reduced rebreathed air volume by 17% up to 100% (all p < 0.001). When wearing facepieces, subjects increased tidal volume (p < 0.001) but not breathing frequency. Oxygen saturation was not influenced by facepieces. With FFP3 respirators PCO2 increased by up to 3.2 mmHg (p < 0.001) at rest but only up to 1.4 mmHg (p < 0.001) when exercising. Discomfort of breathing increased with increasing protection class of the facepiece but was consistently perceived as tolerable. We conclude that the amount of rebreathed air increases with increasing protection class of facepieces. Healthy adults were capable to compensate the facepieces' dead-space by adapting tidal volume at rest and during physical activity; thereby they tolerated moderate increases in PCO2. Ambient airflow may considerably reduce the amount of facepiece related rebreathed air.

A Wearable Open-Source electrical impedance tomography device

Electrical impedance tomography (EIT) is medical imaging technique in which small electrical signals are used to map the electrical impedance distribution within the body. It is safe and non-invasive, which make it attractive for use in continuous monitoring or outpatient applications, but the high cost of commercial devices is an impediment to its adoption. Over the last 10 years, many research groups have developed their own EIT devices, but few designs for open-source EIT hardware are available. In this work, we present a complete open-source EIT system that is designed to be suitable for monitoring the lungs of free breathing subjects. The device is low-cost, wearable, and is designed to comply with the industry accepted safety standard for EIT. The device has been tested in two regimes: Firstly in terms of measurement uncertainty as a voltage measurement system, and secondly against a set of measures that have been proposed specifically for EIT hardware. The voltage measurement uncertainty of the device was measured to be − 0.7 % ± 0.36 mV. The EIT specific performance was measured in a phantom test designed to be as physiologically representative as practicable, and the device performed similarly to other published devices. This work will contribute to increased accessibility of EIT for study and will contribute to consensus on testing methodology for EIT devices.

Investigating effects of FFP2 wearing during physical activity on gas exchange, metabolism and affective state using a randomized controlled trial

Concerns are repeatedly raised about possible adverse respiratory effects of wearing filtering face pieces (FFP) during physical activity. This study compared the impact of FFP type 2 (NF95) on pulmonary function, blood gas values, metabolism and discomfort during light, moderate and vigorous physical activity. Healthy adults (n = 13; 6 females, 7 males; mean 31.3, SD 5.5 years) participated in this randomized two-armed (Ergometer cycling with a FFP type 2 vs. no mask) crossover trial. Baseline cardiopulmonary exercise testing and two interventions (masked and unmasked ergometer cycling 40%, 50% and 70% VO2max, 10 min each) were separated by 48 h washout periods. Spiroergometric data (End tidal carbon dioxide partial pressure PetCO2; breathing frequency; inspiration time), blood gas analysis outcomes (capillary carbon dioxide partial pressure, pCO2) and subjective response (Breathing effort and perceived exertion) were contrasted between conditions using ANOVAs. All participants completed the crossover trial, seven started with the FFP2 condition (No adverse events or side effects). FFP2 decreased breathing frequency, prolonged inspiration time, increased perceived breathing effort and PetCO2 (p < .05). Blood pCO2 in millimetres mercury increased during exercise with 50%VO2max (mean 36.67, SD 3.19 vs. mean 38.46, SD 2.57; p < .05) and 70%VO2max (35.04, 2.84 vs. 38.17, 3.43; p < .05) but not during exercise with 40%VO2max (36.55, 2.73 vs. 38.70). Perceived exertion was not affected (p > 0.05) by mask wearing. Conclusion: Mask-induced breathing resistance decreased respiratory performance and limited pulmonary gas exchange. While FFP2 affected subjective breathing effort per se, invasive diagnostics showed that statistically significant metabolic effects are induced from moderate intensity upwards.Trial registration: DRKS-ID: DRKS00030181, Date of registration: 05/09/2022 (German Register for Clinical Trials).

Breathing changes following mini-implant-supported maxillary skeletal expander treatment in late adolescent or adult patients : Assessment of objective and subjective functional breathing changes.

The aim of this study was to assess objective and subjective breathing changes in adult patients who underwent maxillary skeletal expansion with the mini-implant-supported maxillary skeletal expander (MSE). Twenty-nine patients (mean age 18.1 ± 4.3years) who underwent expansion using the MSE were compared pre- and posttreatment and with acontrol group (mean age 19.9 ± 2.6years) to assess objective and subjective functional breathing changes. Objective measurements of the airway including peak nasal inspiratory flow (PNIF) and peak oral inspiratory flow (POIF) were measured utilizing the In-Check medical device (Clement Clarke, Harlow, United Kingdom). Patients reported subjective breathing assessment utilizing the visual analog scale (VAS). Intragroup comparisons were performed with Wilcoxon tests and intergroup comparison with Mann-WhitneyU tests. Spearman correlation coefficients were calculated among the studied variables (P < 0.05). Following MSE treatment, there were significantly higher values for PNIF total (P < 0.0001), PNIF right (P < 0.0001), PNIF left (P < 0.0001), and POIF (P < 0.01) compared to pretreatment and control group results. Also, patients reported asignificant decrease in troubled breathing as measured by the VAS for breathing through the right nostril (P < 0.01), left nostril (P < 0.001), and both nostrils (P < 0.01). Comparing the objective and subjective variables for both the pre-MSE or post-MSE groups, the results indicated no significant correlation between total PNIF and total VAS. However, the values had significant correlations between PNIF and VAS on each side when the patients were asked to block one nostril. Objective functional breathing measurements were increased immediately after treatment with MSE. Subjective functional breathing measurements changes were significantly higher after MSE treatment and compared with the control group. MSE presents anonsurgical alternative to achieving orthopedic expansion in adult patients which may provide abenefit for patients with nasal airway obstruction.

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Remifentanil improves left ventricular diastolic parameters in patients with impaired diastolic function: a prospective clinical study

BackgroundLeft ventricular diastolic dysfunction has a significant impact on perioperative morbidity and mortality, and its incidence is high in elderly individuals. Anesthetic agents may impair diastolic function, which may increase the incidence of perioperative complications. The aim of this prospective, clinical, phase 4 study was to investigate the effects of remifentanil on left ventricle (LV) diastolic function in patients with diastolic dysfunction. The study was performed on 30 spontaneously breathing subjects (aged 60–80 years) with diastolic dysfunction.MethodsThirty patients (aged 60–80 years) with diastolic dysfunction scheduled for surgery were recruited between November 2019 and March 2023. Left ventricle function was evaluated once the intravenous remifentanil infusion reached a target-controlled concentration of 2 ng/ml with transthoracic echocardiography. Analysis of systolic function focused on left ventricular ejection fraction and mean mitral annular S velocity (Sm), whereas diastolic function focused on changes in transmitral peak flow (E), E/A, mitral septal and lateral e’ waves, E/e’ ratios and left atrial volume index following remifentanil infusion.ResultsDiastolic function measures of LV (mitral E/e’, septal and lateral e’ waves) statistically significantly improved (E/e’ from 10.6 ± 2.9 cm.sn− 1 to 9.5 ± 2.2 cm.sn− 1; p = 0.006) following remifentanil infusion. Left atrial volume index decreased following remifentanil infusion without statistical significance (from 55 ± 14.4 ml.cm− 2 to 51.6 ± 13.3 ml.cm− 2; p = 0.1). Systolic function (ejection fraction and Sm) did not change following remifentanil infusion.ConclusionsRemifentanil improves left ventricular diastolic parameters in patients with preexisting diastolic dysfunction. Our study suggests that remifentanil at a plasma concentration of 2 ng.ml− 1 might be used safely in patients with left ventricular diastolic dysfunction.

A non-invasive continuous and real-time volumetric monitoring in spontaneous breathing subjects based on bioimpedance—ExSpiron®Xi: a validation study in healthy volunteers

Tidal volume (TV) monitoring breath-by-breath is not available at bedside in non-intubated patients. However, TV monitoring may be useful to evaluate the work of breathing. A non-invasive device based on bioimpedance provides continuous and real-time volumetric tidal estimation during spontaneous breathing. We performed a prospective study in healthy volunteers aimed at evaluating the accuracy, the precision and the trending ability of measurements of ExSpiron®Xi as compared with the gold standard (i.e. spirometry). Further, we explored whether the differences between the 2 devices would be improved by the calibration of ExSpiron®Xi with a pre-determined tidal volume. Analysis accounted for the repeated nature of measurements within each subject. We enrolled 13 healthy volunteers, including 5 men and 8 women. Tidal volume, TV/ideal body weight (IBW) and respiratory rate (RR) measured with spirometer (TVSpirometer) and with ExSpiron®Xi (TVExSpiron) showed a robust correlation, while minute ventilation (MV) showed a weak correlation, in both non/calibrated and calibrated steps. The analysis of the agreement showed that non-calibrated TVExSpiron underestimated TVspirometer, while in the calibrated steps, TVExSpiron overestimated TVspirometer. The calibration procedure did not reduce the average absolute difference (error) between TVSpirometer and TVExSpiron. This happened similarly for TV/IBW and MV, while RR showed high accuracy and precision. The trending ability was excellent for TV, TV/IBW and RR. The concordance rate (CR) was >95% in both calibrated and non-calibrated measurements. The trending ability of minute ventilation was limited. Absolute error for both calibrated and not calibrated values of TV, TV/IBW and MV accounting for repeated measurements was variably associated with BMI, height and smoking status. Conclusions: Non-invasive TV, TV/IBW and RR estimation by ExSpiron®Xi was strongly correlated with tidal ventilation according to the gold standard spirometer technique. This data was not confirmed for MV. The calibration of the device did not improve its performance. Although the accuracy of ExSpiron®Xi was mild and the precision was limited for TV, TV/IBW and MV, the trending ability of the device was strong specifically for TV, TV/IBW and RR. This makes ExSpiron®Xi a non-invasive monitoring system that may detect real-time tidal volume ventilation changes and then suggest the need to better optimize the patient ventilatory support.