Subjects Breathing Research Articles

Pulmonary Function and Respiratory Muscle Strength in Patients with Multiple Sclerosis.

Background In patients with multiple sclerosis (MS), there is a decline in muscle strength and physical capacity due to demyelination and axonal loss in the central nervous system. In patients with advanced MS or in a later stage of the disease, also respiratory impairment may occur. The degree of pulmonary dysfunction in the earlier stages of MS has not been thoroughly described. Therefore, the primary aims of this study are to describe pulmonary function and respiratory muscle strength in patients with a moderate disease course and to identify associations between respiratory muscle strength and functional capacity. Methods A sample of 48 patients with a diagnosis of MS and mean age 56 ± 11 years was studied using a descriptive cross-sectional design. The patients had a disease duration of 24 ± 11 years and a median Expanded Disability Status Scale (EDSS) score of 4.5 (interquartile range 4.0-6.5). Pulmonary function assessed by spirometry, respiratory muscle strength, peak cough flow and peripheral oxygen saturation, subjective breathing and coughing ability, and physical capacity measured using the 6MWT were evaluated. Results The patients had normal pulmonary function with no significant abnormalities in dynamic spirometry (vital capacity 103 ± 16% predicted, forced expiratory volume in 1 second 95 ± 15% predicted). Peak expiratory flow rate 89 ± 17% predicted was in the lower limit of normal. Respiratory muscle strength, determined by maximal inspiratory (MIP) and expiratory (MEP) static pressures, was normal but with large differences between individuals. MIP ranged from 26 to 143 cmH2O (98 ± 31% predicted); the MEP values ranged from 43 to 166 cmH2O (104 ± 29% predicted), with two patients having values below the lower limit of normal. Significant positive associations between MIP as well as MEP were found in several pulmonary function variables. A significant negative association was found between EDSS score and MEP (r = −0.312, p = 0.031). Mean peak cough flow was 389 ± 70 L/min, which is comparable with the values reported for healthy adults. The patients did not experience a severely decreased ability to take deep breaths or cough. There was a moderate correlation between MEP and physical capacity, as assessed by the 6MWT (r = 0.399, p = 0.010) and between peak expiratory flow (PEF) and the 6MWT (r = 0.311, p = 0.048). Conclusion Respiratory muscle strength, pulmonary function assessed by spirometry, and peak cough flow were normal in patients with mild to moderate MS; however, there were large individual differences demonstrating low respiratory muscle strength in some patients. Significant associations between MEP and functional capacity and between MEP and disease severity were found, indicating that patients with impaired respiratory muscle strength have lower functional capacity and more severe disease.

Rapid maxillary expansion on oral breathing children: effects on tongue location, hyoid position and breathing. A pilot study.

Oral breathing and downward tongue position are generally associated with transverse hypo-development of the upper maxilla. Rapid maxillary expansion aims to expand the upper maxilla transversely. This pilot retrospective clinical study evaluates the effects of rapid maxillary expansion therapy on the resting position of the tongue, on the position of the hyoid bone and on clinical respiratory pattern in a group of mouth breathing patients with mono- or bilateral cross-bites due to transversal deficits of the maxilla. A total of 39 prepubertal oral breathing subjects with posterior cross-bite (mean age 8.5 year) have been studied. Before (T0) and after treatment (T1), changes in the position of the hyoid bone and tongue were evaluated by comparing latero-lateral radiographs (TLL), while the modification of respiratory patterns by a clinical and anamnestic assessment. After the treatment, the dorsum of tongue moved closer to the palatine vault, the position of the hyoid bone did not undergo significant variations and the respiratory pattern clinically improved in 64% of subjects. In patients in early stages of oral respiratory development, rapid maxillary expansion promoted correct tongue position but did not produce significant changes in the position of the hyoid bone. It has been observed a general improvement of the breathing pattern.

The distorted power of medical surgical masks for changing the human thermal psychology of indoor personnel in summer.

The medical surgical mask (MSM) has been the essential protective equipment in people's daily work. The experimental purpose is to explore the effects of wearing MSM on human thermal sensation, thermal comfort, and breathing comfort in office buildings in summer. A total of 30 healthy college students were recruited for the testing. The experiment was carried out in a climate chamber, which can simulate the office buildings in summer. The experiment collects the subjects’ skin temperature, microclimate in the mask, and subjective votes, including thermal sensory votes (TSV), thermal comfort votes (TCV), and respiratory comfort votes (BCV). Experimental results show that wearing MSM has no significant effect on the skin temperature of the human body. The microclimate temperature inside the MSM reaches over 34℃, and the relative humidity reaches over 70%. The high‐temperature and high‐humidity microclimate put human beings in an uneven thermal environment, which leads to poor human tolerance to the thermal environment and becomes the main reason for destroying human thermal comfort. Wearing MSM has a significant impact on the subjective thermal sensation, thermal comfort, and breathing comfort of the human body, and the impact becomes more significant as the environmental temperature increases. Once the mask is taken off, the human body will enter an extremely comfortable environment, resulting in an excessively high vote value. The difference in voting values before and after removing the mask becomes larger with the environmental temperature. By fitting the voting results and perform data processing, it can be found that wearing MSM will reduce the neutral temperature by 1.5°C, and the environmental temperature with the optimal thermal comfort by 1.4°C, and as the temperature increases, the respiratory discomfort will become more and more intense. Regardless of whether wearing a MSM, the subjects preferred a slight warmer environment. In conclusion, with the increase of ambient temperature, wearing MSM can cause the human worse tolerance to the thermal environment, and this disturbance will become more and more intense.

Smart Mandibular Advancement Device for Intraoral Monitoring of Cardiorespiratory Parameters and Sleeping Postures.

Obstructive sleep apnea (OSA), as a highly prevalent sleep disorder, causes several serious health complaints. It has been proved that using intraoral mandibular advancement devices (MADs) during sleep is an efficient treatment for OSA. However, due to limited number of sleep study laboratories, effectiveness of MAD therapy is not regularly monitored. This paper proposes a smart MAD with the capability of continuously monitoring of cardiorespiratory parameters as well as sleeping postures and breathing routes. In this regard, a flexible hybrid wireless sensing platform based on the intraoral photoplethysmography (PPG), temperature and accelerometry monitoring is developed. It is qualitatively and quantitatively discussed that the intraorally captured PPG signals by the smart MAD have similar features as the ones received from the conventional anatomical position, i.e., the left index fingertip. Extensive experimental measurements indicate that the proposed smart MAD can estimate heart-rate (HR), respiration rate (RR) and blood oxygen saturation (SpO2) with the maximum mean-absolute-errors of 2.4 bpm, 2.52 breaths/min, and 0.8%, respectively, in comparison to the reference measurements, while such a capability is not dependent on subject's positions and breathing routes. It is also shown that the smart MAD can readily identify different sleeping postures, namely, supine, left, right, and prone and breathing routes. The reliability and stability of the proposed smart MAD's measurements are proved by examining a group of subjects. The proposed smart MAD has potential to monitor the effectiveness of MAD treatment and eliminate untreated OSA without the requirement of attaching an extra monitoring platform to the patient's body.

Textile-Based Pressure Sensing Matrix for In-Bed Monitoring of Subject Sleeping Posture and Breathing Activity

According to current trends in healthcare sensing technologies, we describe a textile-based pressure sensing matrix that can be integrated in the mattress of a smart bed to characterize sleeping posture/movement of a subject and to extract breathing activity. The pressure mapping layer is developed as a matrix of 195 piezoresistive sensors, it is entirely made of textile materials, and it is the basic component of a smart bed that can perform sleep analysis, can extract physiological parameters, and can detect environmental data related to subject’s health. In this paper, we show the principle of the pressure mapping layer and the architecture of the dedicated electronic system that we developed for signal acquisition. In addition, we describe the algorithms for posture/movement classification (dedicated artificial neural network) and for extraction of the breathing rate (frequency domain analysis). We also perform validation of the system to quantify the accuracy/precision of the posture classification and the statistical analysis to compare our breathing rate estimation with the gold standard.

Using breath analysis as a screening tool to detect gastric cancer: A systematic review.

175 Background: In its early stages, gastric cancer symptoms are frequently lacking, resulting in an often late and incurable diagnosis. A non-invasive, cheap, and reliable screening method for gastric cancer could improve outcomes and increase the number of surgically resectable gastric cancers. Breath analysis has emerged as an experimental method of non-invasive screening of gastric cancer and identification of individuals suitable for confirmatory, diagnostic upper gastrointestinal endoscopy. We aimed to evaluate the accuracy and applicability of breath analysis for gastric cancer detection in adults. Methods: This systematic review searched MEDLINE, EMBASE, BIOSIS, CENTRAL, and Compendex until 11 July 2019 for original studies analyzing exhaled breath to detect gastric cancer in patients. Two authors then independently screened the abstracts, titles, and full texts. Summary sensitivity and specificity analyses were obtained using a hierarchical bivariate method. Positive predictive value and number needed to screen (NNS) of breath analysis methods for gastric cancer detection were calculated for each country using gastric cancer prevalence by country obtained from the Global Cancer Observatory. Non-quantitative results were descriptively summarized. Risk of bias was assessed using the QUADAS-2 tool. This study protocol was pre-registered in PROSPERO (CRD42020139422). Results: Twenty studies were included. Together, the studies included 2,976 subjects. The pooled mean age of the subjects in the gastric cancer groups was 60.5 ± 11 years while the pooled mean age for control groups was 55.4 ± 12 years. Within these twenty studies, breath analysis technologies most commonly used were mass spectrometry (MS)-based methods; other methods included volatile organic compound sensors, thermal desorption tubes, and silicon nanowire field effect transistors. Across all included studies, we found and summarized the characteristics of 131 chemical compounds found in the exhaled breath of study subjects. Eleven studies (total n = 1905) involving all technologies reported quantitative results, with sensitivities ranging from 67-100% and specificities from 71-98%. The summary sensitivity across six studies utilizing MS-based breath analysis methods was 85.3% (95% CI: 82-96%); summary specificity was 81.7%. (95% CI: 78-85%). Based on the MS-based values, we estimated that screening with MS-based breath tests could lower the NNS by more than four-fold in the 15 countries with the highest prevalence of gastric cancer. Conclusions: Breath analysis is a promising method for gastric cancer detection with good diagnostic performance and potential to decrease the NNS for endoscopy-based gastric cancer detection. However, due to the heterogeneity of breath analysis technologies, rigorous studies with standardized, reproducible methods are needed to evaluate the clinical applicability of these technologies.

Evaluation of Regional Pulmonary Ventilation in Spontaneously Breathing Patients with Idiopathic Pulmonary Fibrosis (IPF) Employing Electrical Impedance Tomography (EIT): A Pilot Study from the European IPF Registry (eurIPFreg).

Objectives: In idiopathic pulmonary fibrosis (IPF), alterations in the pulmonary surfactant system result in an increased alveolar surface tension and favor repetitive alveolar collapse. This study aimed to assess the usefulness of electrical impedance tomography (EIT) in characterization of regional ventilation in IPF. Materials and methods: We investigated 17 patients with IPF and 15 healthy controls from the University of Giessen and Marburg Lung Center (UGMLC), Germany, for differences in the following EIT parameters: distribution of ventilation (TID), global inhomogeneity index (GI), regional impedance differences through the delta of end-expiratory lung impedance (dEELI), differences in surface of ventilated area (SURF), as well as center of ventilation (CG) and intratidal gas distribution (ITV). These parameters were assessed under spontaneous breathing and following a predefined escalation protocol of the positive end-expiratory pressure (PEEP), applied through a face mask by an intensive care respirator (EVITA, Draeger, Germany). Results: Individual slopes of dEELI over the PEEP increment protocol were found to be highly significantly increased in both groups (p < 0.001) but were not found to be significantly different between groups. Similarly, dTID slopes were increasing in response to PEEP, but this did not reach statistical significance within or between groups. Individual breathing patterns were very heterogeneous. There were no relevant differences of SURF, GI or CGVD over the PEEP escalation range. A correlation of dEELI to FVC, BMI, age, or weight did not forward significant results. Conclusions: In this study, we did see a significant increase in dEELI and a non-significant increase in dTID in IPF patients as well as in healthy controls in response to an increase of PEEP under spontaneous breathing. We propose the combined measurements of EIT and lung function to assess regional lung ventilation in spontaneously breathing subjects.

Dexmedetomidine-Tiletamine-Zolazepam Followed by Inhalant Anesthesia in Spectacled Bears (Tremarctos ornatus)

Background: The spectacled bear (Tremarctos ornatus) is the only bear species inhabiting South America and is classified as vulnerable according to the International Union for Conservation of Nature (IUCN) Red List. Among the few publications on the use of general anesthesia and advanced monitoring of ursids in veterinary hospital settings, little is described regarding chemical restraint, general anesthesia and monitoring of spectacled bears. This case series describes the use of a dexmedetomidine-tiletamine-zolazepam chemical restraint combination and its effects on cardiorespiratory variables and arterial blood gases observed in two spectacled bears submitted to isoflurane anesthesia for imaging and/or surgical procedures.Cases: Two female, one adult and one senile, all-term captive spectacled bears were referred to the Veterinary Medical Teaching Hospital at the Universidade Estadual Paulista - Unesp, Botucatu campus, both with a presumable history of recent trauma. After immobilization with an intramuscular (IM) administration of tiletamine-zolazepam (3.8 - 4.3 mg/kg) and dexmedetomidine (6.4 - 7.6 µg/kg), anesthesia induction was achieved by means of intravenous (IV) propofol (1 - 2 mg/kg). The patients then underwent isoflurane inhalant anesthesia and were submitted to intermittent positive-pressure ventilation through the remainder of the procedures. Initial settings of inspiratory flow rate were adjusted to obtain Ppeak of 10 cmH2O and tidal volumes (Vt) of 10 mL/kg, as well as respiratory rates (ƒR)and inspiration-to-expiration (I:E) ratio of 10 breaths/min and 1:2, respectively, and were then adjusted throughout anesthesia to maintain normocapnia (end-tidal carbon dioxide concentrations between35 and 45 mmHg). One of the individuals was chemically restrained (6.4 mg/kg of tiletamine-zolazepam and 7.7 µg/kg of dexmedetomidine) on a second anesthetic event for imaging procedures. Arterial blood gas analysis were performed with the subjects breathing room air and oxygen-enriched air. Both animals exhibited severe hypoxemia (partial pressure of oxygen [PaO2] &lt; 60 mmHg) while breathing room air (inspired oxygen fraction [FiO2] ≅ 0.21). An impaired blood oxygenation (PaO2/FiO2 &lt; 400) was still observed despite mechanical ventilation and the provision of 1.0 FiO2. Alveolar recruitment maneuvers (3 sequential mechanical sights with peak airway pressure at 20 - 30 cmH2O during 15 - 30 s each) were then performed, which resulted in improved PaO2/FiO2 ratios. All other blood gas, electrolytes and acid-base variables did not appear to be importantly altered by chemical restraint and general anesthesia.Discussion: Dexmedetomidine-tiletamine-zolazepam resulted in reliable chemical restraints and is a feasible option for immobilizing spectacled bears, though severe hypoxemia may proceed. Hypoxemia is the most commonly described complication in bear anesthesia, and was also evidenced in the current report. However, low PaO2/FiO2 ratios tend to be accompanied by hypercapnia and therefore counteracted by oxygen supplementation in bears, which was not observed in the present report. In fact, blood oxygenation only reached regular values after alveolar recruitment maneuvers, which is compatible to an atelectasis-related hypoxemia. Therefore, either inhalant anesthesia or field chemical restraint should be accompanied by advanced monitoring (cardiorespiratory variables and blood gas analysis) in until further studies address the management of hypoxemia in spectacled bear. since Advanced monitoring was of major importance for a safe outcome and an uneventful recovery in this species.Keywords: balanced anesthesia, dexmedetomidine, general anesthesia, spectacled bear, Tremarctos ornatus, wildlife.

Effects of Lower Rib Expansion Limitation on Maximal Respiratory Pressure and Abdominal Muscle Activity During Maximal Breathing in Healthy Subjects

Effects of Lower Rib Expansion Limitation on Maximal Respiratory Pressure and Abdominal Muscle Activity During Maximal Breathing in Healthy Subjects

Free-breathing radial imaging using a pilot-tone radiofrequency transmitter for detection of respiratory motion.

To describe an approach for detection of respiratory signals using a transmitted radiofrequency (RF) reference signal called Pilot-Tone (PT) and to use the PT signal for creation of motion-resolved images based on 3D stack-of-stars imaging under free-breathing conditions. This work explores the use of a reference RF signal generated by a small RF transmitter, placed outside the MR bore. The reference signal is received in parallel to the MR signal during each readout. Because the received PT amplitude is modulated by the subject's breathing pattern, a respiratory signal can be obtained by detecting the strength of the received PT signal over time. The breathing-induced PT signal modulation can then be used for reconstructing motion-resolved images from free-breathing scans. The PT approach was tested in volunteers using a radial stack-of-stars 3D gradient echo (GRE) sequence with golden-angle acquisition. Respiratory signals derived from the proposed PT method were compared to signals from a respiratory cushion sensor and k-space-center-based self-navigation under different breathing conditions. Moreover, the accuracy was assessed using a modified acquisition scheme replacing the golden-angle scheme by a zero-angle acquisition. Incorporating the PT signal into eXtra-Dimensional (XD) motion-resolved reconstruction led to improved image quality and clearer anatomical depiction of the lung and liver compared to k-space-center signal and motion-averaged reconstruction, when binned into 6, 8, and 10 motion states. PT is a novel concept for tracking respiratory motion. Its small dimension (8 cm), high sampling rate, and minimal interaction with the imaging scan offers great potential for resolving respiratory motion.

Induction of dynamic hyperinflation by expiratory resistance breathing in healthy subjects - an efficacy and safety study.

New Findings What is the central question of this study? The study aimed to establish a novel model to study the chronic obstructive pulmonary disease (COPD)‐related cardiopulmonary effects of dynamic hyperinflation in healthy subjects. What is the main finding and its importance? A model of expiratory resistance breathing (ERB) was established in which dynamic hyperinflation was induced in healthy subjects, expressed both by lung volumes and intrathoracic pressures. ERB outperformed existing methods and represents an efficacious model to study cardiopulmonary mechanics of dynamic hyperinflation without potentially confounding factors as present in COPD. Dynamic hyperinflation (DH) determines symptoms and prognosis of chronic obstructive pulmonary disease (COPD). The induction of DH is used to study cardiopulmonary mechanics in healthy subjects without COPD‐related confounders like inflammation, hypoxic vasoconstriction and rarefication of pulmonary vasculature. Metronome‐paced tachypnoea (MPT) has proven effective in inducing DH in healthy subjects, but does not account for airflow limitation. We aimed to establish a novel model incorporating airflow limitation by combining tachypnoea with an expiratory airway stenosis. We investigated this expiratory resistance breathing (ERB) model in 14 healthy subjects using different stenosis diameters to assess a dose–response relationship. Via cross‐over design, we compared ERB to MPT in a random sequence. DH was quantified by inspiratory capacity (IC, litres) and intrinsic positive end‐expiratory pressure (PEEPi, cmH2O). ERB induced a stepwise decreasing IC (means (95% CI): tidal breathing: 3.66 (3.45–3.88), ERB 3 mm: 3.33 (1.75–4.91), 2 mm: 2.05 (0.76–3.34), 1.5 mm: 0.73 (0.12–1.58) litres) and increasing PEEPi (tidal breathing: 0.70 (0.50–0.80), ERB 3 mm: 11.1 (7.0–15.2), 2 mm: 22.3 (17.1–27.6), 1.5 mm: 33.4 (3.40–63) cmH2O). All three MPT patterns increased PEEPi, but to a far lesser extent than ERB. No adverse events during ERB were noted. In conclusion, ERB was proven to be a safe and efficacious model for the induction of DH and might be used for the investigation of cardiopulmonary interaction in healthy subjects.

Breathless in Beijing: Aerial Attunements and China’s New Respiratory Publics

For all of its protean and ephemeral qualities, air exerts a remarkably muscular influence on urban form and contemporary life in China. In recent years, as the breakneck speed of China’s development has altered the very chemistry of the atmosphere, the boundaries between breathing subjects and their toxic environments have become increasingly blurred. In this climate, Beijing inhabitants have sought out various modes of respiratory refuge, reorganizing the city into new spaces of atmospheric fortification. As deadly air divides Beijing into a series of protected insides and precarious outsides, life is increasingly being reoriented toward the dangers and imperatives of breathing in the Chinese city. Yet alongside the growing stratification of breathing experiences in the capital, shared exposure is also reconfiguring public life and landscapes through new solidarities and entwined fates. Engaging Beijing’s emergent respiratory publics online, behind face masks, and inside conditioned air spaces, I explore how collective exposure is galvanizing new modes of atmospheric recognition in China. Specifically, I suggest that respiratory publics make invisible threats visible by mobilizing everyday objects, practices, and social life to render air both an object of concern and a site of intervention. Ultimately, by attending to how attunements to air pollution emerge through everyday practices and quotidian habits, this article expands upon a growing body of STS scholarship investigating how social life is increasingly constituted in and through atmospheric entanglements.

A High performance electronic nose system for the recognition of myocardial infarction and coronary artery diseases

Electronic noses are devices that detect the number and level of chemicals in an odor. This is accomplished by means of chemical gas sensors in the device’s structure. The device recognizes the odors that were introduced to it via the software. When we breathe air, several gas exchanges take place in our lungs (e.g., O2-CO2 at the alveola-capillary level). Some gases in our blood are presented with our breath. The detection of these gases can provide information about our health. Nowadays, many diseases can be diagnosed with very high accuracy by using an electronic nose. Despite advances in diagnoses and treatments, cardiovascular disease is still the leading cause of mortality worldwide. Coronary artery disease is the leading cause of cardiovascular mortality and morbidity. The ability to diagnose coronary artery disease from the breath will accelerate the diagnosis, and thus, the initiation of treatment, which may save many lives. This study, involved an investigation of whether or not diseases (e.g., myocardial infarction, stable coronary artery disease) can be diagnosed from exhaled respiratory air using an electronic nose. This involved collecting data on exhaled breath from 33 patients diagnosed with myocardial infarction that underwent a primary percutaneous coronary intervention, 22 patients with stable coronary artery disease and 26 patients without heart disease. An electronic nose containing 19 gas sensors was manufactured for this study. The respondents’ breath was collected in a sterile manner. The statistical features including mean, skewness, kurtosis and derivative variance were extracted from the breath samples. These features were classified for the entire database using the support vector machine classifier by selecting 66 % as a training set and 34 % as a test set. The breath from the myocardial infarction patients were separated from that of the healthy individuals and the stable coronary artery disease patients with a classification accuracy rate of 97.19 %. The breath from the stable coronary artery disease patients were separated from the breath of the healthy control subjects with a classification accuracy rate of 81.48 %. The results reveal that the proposed method has great potential for myocardial infarction, stable coronary artery disease and healthy subjects when the electronic nose is used to record the exhaled respiratory air of the participants.

Acute Effects of Sitting Out of Bed and Exercise on Lung Aeration and Oxygenation in Critically Ill Subjects.

Early mobilization during critical illness is safe and has beneficial effects on functional outcomes. However, its impact on pulmonary function has not been thoroughly explored. We hypothesized that a sitting position out of bed coupled with exercise could result in an improvement in oxygenation and lung aeration. The study was conducted on a cohort of adult subjects within a week of their admission to an ICU. Subjects were transferred to a chair and undertook a 15-min session of exercise, either active or passive. Subjects in the control group were only transferred to a chair. Electrical impedance tomography, a reliable bedside technique monitoring regional lung aeration and the distribution of ventilation, was continuously performed, and blood gases were assessed at baseline and 20 min post-exercise. The cohort included 40 subjects, 17 of whom were mechanically ventilated and 23 spontaneously breathing. The control group for each modality consisted of 5 mechanically ventilated or 5 spontaneously breathing subjects. Mild hypoxemia was present in 45% of the spontaneously breathing cohort, whereas the mechanically ventilated subjects demonstrated moderate (50%) or severe (12%) hypoxemia. Compared with the control group, early mobilization induced a significant increase in lung aeration. In mechanically ventilated subjects, lung aeration increased, especially in the anterior lung regions (mean impedance [95% CI]: T1 (baseline in bed) = 1,265 [691-1,839]; T2 (chair sitting) = 2,003 [1,042-2,963]; T3 (exercise) = 1,619 [810 2,427]; T4 (post exercise in chair) = 2,320 [1,186-3,455]). In spontaneously breathing subjects, lung aeration increased mainly in the posterior lung regions (mean impedance [95% CI]: T1 = 380 [124-637]; T2 = 655 [226-1,084]; T3 = 621 [335-906]; T4 = 600 [340-860]). [Formula: see text] increased, especially in subjects with lower [Formula: see text] at baseline (< 200) (133 ± 31 to 158 ± 48, P = .041). For critically ill subjects, a sitting position and exercise increased lung aeration and were associated with an improvement in [Formula: see text] in the more severely hypoxemic subjects.

Traube-Hering waves are formed by interaction of respiratory sinus arrhythmia and pulse pressure modulation in healthy men.

Excessive blood pressure variation is linked to the development of hypertension and other diseases. This study assesses the relative role of respiratory sinus arrhythmia (RSA) and pulse pressure (PP) on the amplitude and timing of blood pressure variability with respiration [Traube-Hering (TH) waves]. We analyzed respiratory, electrocardiogram, and blood pressure traces from healthy, supine male subjects (n = 10, mean age = 26.7 ± 1.4) during 20-min epochs of resting, slow deep breathing (SDB), and recovery. Across all epochs, blood pressure and heart rate (HR) were modulated with respiration and the magnitude of RSA; TH waves increased during SDB. The data were deconstructed using a simple mathematical model of blood pressure to dissect the relative roles of RSA and PP on TH waves. We constructed the time series of the R-wave peaks and compared the recorded TH waves with that predicted by the model. Given that cardiac output is determined by both heart rate and stroke volume, it was surprising that the magnitude of the TH waves could be captured by only HR modulation. However, RSA alone did not accurately predict the timing of TH waves relative to the respiratory cycle. Adding respiratory modulation of PP to the model corrected the phase shift showing the expected pattern of BP rising during inspiration with the peak of the TH wave during early expiration. We conclude that short-term variability of blood pressure referred to as TH waves has at least two independent mechanisms whose interaction forms their pattern: RSA and respiratory-driven changes in PP.NEW & NOTEWORTHY Variability in blood pressure has become an important metric to consider as more is learned about the link between excessive blood pressure variability and adverse health outcomes. In this study using slow deep breathing in human subjects, we found that heart rate and pulse pressure variations have comparable effects on the amplitude of blood pressure waves, and it is the common action of the two that defines the phase relationship between respiration and blood pressure oscillations.

An alternative way to measure total lung capacity: a pilot study

Abstract Total lung capacity is usually measured by a body plethysmograph or helium dilution methods. In this study an alternative approach to obtain total lung capacity of spontaneous breathing subjects is introduced. The device utilises an optoelectronic plethysmograph and a small tube, which measures mouth pressure and allows total lung capacity to be obtained, which differs less than 0.4 L from the total lung capacity of the body plethysmograph. The method shows potential to be a less burdensome method to estimate total lung capacity determination than the body plethysmograph.

Ideation and assessment of a nitric oxide delivery system for spontaneously breathing subjects

BackgroundThere is an increasing interest in safely delivering high dose of inhaled nitric oxide (NO) as an antimicrobial and antiviral therapeutics for spontaneously breathing patients. A novel NO delivery system is described. MethodsWe developed a gas delivery system that utilizes standard respiratory circuit connectors, a reservoir bag, and a scavenging chamber containing calcium hydroxide. The performance of the system was tested using a mechanical lung, assessing the NO concentration delivered at varying inspiratory flows. Safety was assessed in vitro and in vivo by measuring nitrogen dioxide (NO2) levels in the delivered NO gas. Lastly, we measured the inspired and expired NO and NO2 of this system in 5 healthy subjects during a 15-min administration of high dose NO (160 parts-per-million, ppm) using our delivery system. ResultsThe system demonstrated stable delivery of prescribed NO levels at various inspiratory flow rates (0–50 L/min). The reservoir bag and a high flow of entering air minimized the oscillation of NO concentrations during inspiration on average 4.6 ppm for each 10 L/min increment in lung inspiratory flow.The calcium hydroxide scavenger reduced the inhaled NO2 concentration on average 0.9 ppm (95% CI -1.58, −0.22; p = .01). We performed 49 NO administrations of 160 ppm in 5 subjects. The average concentration of inspired NO was 164.8±10.74 ppm, with inspired NO2 levels of 0.7±0.13 ppm. The subjects did not experience any adverse events; transcutaneous methemoglobin concentrations increased from 1.05±0.58 to 2.26±0.47%. ConclusionsThe system we developed to administer high-dose NO for inhalation is easy to build, reliable, was well tolerated in healthy subjects.

Abstract 744: Volatile organic compounds (VOCs) from exhaled Breath for lung cancer Staging using TD-GC-MS

Abstract Background: Breath analysis is a promising noninvasive screening technique that offers a wide range of probable possibilities to facilitate early diagnosis of lung cancer (LC). Method: Exhaled breath samples of 352 subjects were analyzed to detect C6∼C30 VOCs through thermal desorption coupled with gas chromatography-mass spectrometry (TD-GC-MS). Data were divided into three categories Lung Cancer (LC), Benign Pulmonary Disease (BPD) and Healthy control (HC). Statistical classification models were used to analyze VOCs to distinguish between HC, BPD and LC patient's early and advanced stages. Receiver operator characteristics (ROC) curves were used to select different VOCs to evaluate the accuracy, specificity, and sensitivity of the diagnostic model. Results: The analysis resulted that 10,9,11 and 10 VOCs have a significant correlation to discriminate Histology, stage, BPD from LC and HC from LC. The diagnostic model predicted accuracy, sensitivity, and specificity of NSCLC vs. SCLC is 92%, 96% and 90% with area under curve AUC&amp;gt;0.913. As of ROC curve with AUC&amp;gt;0.819 has distinguished Stage I-II vs. stage III-IV with accuracy, sensitivity, and specificity 72%, 84%, and 80%. Whereas the ROC curve with AUC&amp;gt;0.795 has distinguished BPD from LC with accuracy, sensitivity, and specificity 83%, 89%, and 84%. While ROC curve with AUC&amp;gt;0.945, accuracy, sensitivity and specificity 92%, 96%, and 90% have distinguished HC from LC. Conclusion: This study confirms that TD GC-MS is a sensitive and dependable method to distinguish the VOCs in exhaled breath. We have witnessed significant differences in breath of BPD, HC and LC subjects. Where 10,8,11 and 10 VOCs have distinguished between early from the advance stage, NSCLC from SCLC, BPD from LC and HC from LC. These VOCs has the potential to help improve LC diagnosis and prognosis. However, with the expansion of multi centers to other regions could result in more vital findings and will help improve breath analysis and the diagnosis standard. Keywords: Breath Analysis, VOC markers, lung cancer, TD-GC-MS. Citation Format: Kanhar Ghulam Muhammad, Channa Madeeha, Fu Wei, Xu Lin Xin, Yanjie Hu, Kejing Ying, Jun Liu, Xing Chen. Volatile organic compounds (VOCs) from exhaled Breath for lung cancer Staging using TD-GC-MS [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 744.

Detection of strong inspiratory efforts from the analysis of central venous pressure swings: a preliminary clinical study.

Swings of central venous pressure (ΔCVP) may reflect those of pleural and esophageal (ΔPES) pressure and, therefore, the strength of inspiration. Strong inspiratory efforts can produce some harm. Herein we preliminarily assessed the diagnostic accuracy of ΔCVP for strong inspiratory efforts in critically-ill subjects breathing spontaneously. We measured ΔCVP and ΔPES in 48 critically-ill subjects breathing spontaneously with zero end-expiratory pressure (ZEEP) or 10 cmH<inf>2</inf>O of continuous positive airway pressure (CPAP). The overall diagnostic accuracy of ΔCVP for strong inspiratory efforts (arbitrarily defined as ΔPES >8 mmHg) was described as the area under the receiver operating characteristic (ROC) curve, with 0.50 indicating random guess. The agreement between ΔCVP and ΔPES was assessed with the Bland-Altman analysis. ΔCVP recognized strong inspiratory efforts with an area under the ROC curve of 0.95 (95% confidence intervals, 0.85-0.99) with ZEEP and 0.89 (0.76-0.96) with CPAP, both significantly larger than 0.50 (P<0.001). With the best cut-off value around 8 mmHg, the diagnostic accuracy of ΔCVP was 0.92 (0.80-0.98) with ZEEP and 0.94 (0.83-0.99) with CPAP. With ZEEP, the median difference between ΔCVP and ΔPES (bias) was -0.2 mmHg, and the 95% limits of agreement (LoA) were -3.9 and +5.5 mmHg. With CPAP, bias was -0.1 mmHg, and 95%-LoA were -5.8 and +4.5 mmHg. In both cases, ΔCVP correlated with ΔPES (r<inf>s</inf> 0.81 and 0.67; P<0.001 for both). In critically-ill subjects breathing spontaneously, ΔCVP recognized strong inspiratory efforts with acceptable accuracy. Even so, it sometimes largely differed from ∆PES.

Testing Antemortem Blood for Ethanol Concentration from a Blood Kit in a Refrigerator Fire

The stability of ethanol in antemortem blood stored under various conditions has been widely studied. Antemortem blood samples stored at refrigerated temperature, at room temperature, and at elevated temperatures tend to decrease in ethanol concentration with storage. It appears that the stability of ethanol in blood exposed to temperatures greater than 38°C has not been evaluated. The case presented here involves comparison of breath test results with subsequent analysis of blood drawn at the time of breath testing. However, the blood tubes were in a refrigerator fire followed by refrigerated storage for 5months prior to analysis by headspace gas chromatography. The subject's breath was tested twice using an Intoxilyzer 8000. The subject's blood was tested in duplicate using an Agilent headspace gas chromatograph. The measured breath ethanol concentration was 0.103g/210L and 0.092g/210L. The measured blood ethanol concentration was 0.0932g/dL for both samples analyzed. Although the mean blood test result was slightly lower than the mean breath test result, the mean breath test result was within the estimated uncertainty of the mean blood test result. Even under the extreme conditions of the blood kit being in a refrigerator fire, the measured blood ethanol content agreed well with the paired breath ethanol test.