Effects of COVID-19 protective face masks and wearing durations on respiratory haemodynamic physiology and exhaled breath constituents.

BACKGROUND: While assumed to protect against coronavirus transmission, face masks may have effects on respiratory-haemodynamic parameters. Within this pilot study, we investigated immediate and progressive effects of FFP2 and surgical masks on exhaled breath constituents and physiological attributes in 30 adults at rest. METHODS: We continuously monitored exhaled breath profiles within mask space in older (age 60-80 years) and young to middle-aged (age 20-59 years) adults over the period of 15 and 30 min by high-resolution real-time mass-spectrometry. Peripheral oxygen saturation (S pO2 ) and respiratory and haemodynamic parameters were measured (noninvasively) simultaneously. RESULTS: Profound, consistent and significant (p≤0.001) changes in S pO2 (≥60_FFP2-15 min: 5.8±1.3%↓, ≥60_surgical-15 min: 3.6±0.9%↓, <60_FFP2-30 min: 1.9±1.0%↓, <60_surgical-30 min: 0.9±0.6%↓) and end-tidal carbon dioxide tension (P ETCO2 ) (≥60_FFP2-15 min: 19.1±8.0%↑, ≥60_surgical-15 min: 11.6±7.6%↑, <60_FFP2- 30 min: 12.1±4.5%↑, <60_surgical- 30 min: 9.3±4.1%↑) indicate ascending deoxygenation and hypercarbia. Secondary changes (p≤0.005) to haemodynamic parameters (e.g. mean arterial pressure (MAP) ≥60_FFP2-15 min: 9.8±10.4%↑) were found. Exhalation of bloodborne volatile metabolites, e.g. aldehydes, hemiterpene, organosulfur, short-chain fatty acids, alcohols, ketone, aromatics, nitrile and monoterpene mirrored behaviour of cardiac output, MAP, S pO2 , respiratory rate and P ETCO2 . Exhaled humidity (e.g. ≥60_FFP2-15 min: 7.1±5.8%↑) and exhaled oxygen (e.g. ≥60_FFP2-15 min: 6.1±10.0%↓) changed significantly (p≤0.005) over time. CONCLUSIONS: Breathomics allows unique physiometabolic insights into immediate and transient effects of face mask wearing. Physiological parameters and breath profiles of endogenous and/or exogenous volatile metabolites indicated putative cross-talk between transient hypoxaemia, oxidative stress, hypercarbia, vasoconstriction, altered systemic microbial activity, energy homeostasis, compartmental storage and washout. FFP2 masks had a more pronounced effect than surgical masks. Older adults were more vulnerable to FFP2 mask-induced hypercarbia, arterial oxygen decline, blood pressure fluctuations and concomitant physiological and metabolic effects.

Detection of Paratuberculosis in Dairy Herds by Analyzing the Scent of Feces, Alveolar Gas, and Stable Air.

Paratuberculosis is an important disease of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). Early detection is crucial for successful infection control, but available diagnostic tests are still dissatisfying. Methods allowing a rapid, economic, and reliable identification of animals or herds affected by MAP are urgently required. This explorative study evaluated the potential of volatile organic compounds (VOCs) to discriminate between cattle with and without MAP infections. Headspaces above fecal samples and alveolar fractions of exhaled breath of 77 cows from eight farms with defined MAP status were analyzed in addition to stable air samples. VOCs were identified by GC-MS and quantified against reference substances. To discriminate MAP-positive from MAP-negative samples, VOC feature selection and random forest classification were performed. Classification models, generated for each biological specimen, were evaluated using repeated cross-validation. The robustness of the results was tested by predicting samples of two different sampling days. For MAP classification, the different biological matrices emitted diagnostically relevant VOCs of a unique but partly overlapping pattern (fecal headspace: 19, alveolar gas: 11, stable air: 4-5). Chemically, relevant compounds belonged to hydrocarbons, ketones, alcohols, furans, and aldehydes. Comparing the different biological specimens, VOC analysis in fecal headspace proved to be most reproducible, discriminatory, and highly predictive.

Effects of modular ion-funnel technology onto analysis of breath VOCs by means of real-time mass spectrometry.

Proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a powerful tool for real-time monitoring of trace concentrations of volatile organic compounds (VOCs). The sensitivity of PTR-ToF-MS also depends on the ability to effectively focus and transmit ions from the relatively high-pressure drift tube (DT) to the low-pressure mass analyzer. In the present study, a modular ion-funnel (IF) is placed adjacent to the DT of a PTR-ToF-MS instrument to improve the ion-focusing. IF consists of a series of electrodes with gradually decreasing orifice diameters. Radio frequency (RF) voltage and direct current (DC) electric field are then applied to the electrodes to get the ions focused. We investigated the effect of the RF voltage and DC field on the sensitivity of a pattern of VOCs including hydrocarbons, alcohols, aldehydes, ketones, and aromatic compounds. In a proof-of-concept study, the instrument operating both as normal DT (DC-mode) and at optimal IF conditions (RF-mode) was applied for the breath analysis of 21 healthy human subjects. For the range of investigated VOCs, an improvement of one order of magnitude in sensitivity was observed in RF-mode compared with DC-mode. Limits of detection could be improved by a factor of 2-4 in RF-mode compared with DC-mode. Operating the instrument in RF-mode allowed the detection of more compounds in the exhaled air compared with DC-mode. Incorporation of the IF considerably improved the performance of PTR-ToF-MS allowing the real-time monitoring of a larger number of potential breath biomarkers. Graphical abstract.

Extending PTR based breath analysis to real-time monitoring of reactive volatile organic compounds.

Reactive exhaled volatile organic compounds (VOCs) such as nitrogen- and sulfur-containing substances may be related to diseases, metabolic processes and bacterial activity. As these compounds may interact with any surface of the analytical system, time-resolved monitoring and reliable quantification is difficult. We describe a proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) based analytical method for direct breath-resolved monitoring of reactive compounds. Aliphatic amines were used as test substances. Matrix adapted gas standards were generated by means of a liquid calibration unit. Calibration conditions were adapted in terms of materials, temperature and equilibration time. PTR-ToF-MS conditions were optimized in terms of inlet materials, transfer line and drift tube temperature and drift tube reduced electric field (E/N). Optimized PTR conditions in combination with inert materials and high temperatures considerably reduced the interactions of compounds with the surfaces of the analytical system. Good linearity (R2 > 0.99, RSDs < 5%) with LODs between 0.15 ppbV and 1.23 ppbV and LOQs between 0.24 ppbV and 1.94 ppbV could be achieved. The method was then applied to breath-resolved monitoring of reactive compounds in 17 healthy subjects after high and low oral protein challenge. Exhaled concentrations of trimethylamine, indole, methanethiol, dimethylsulfide, acetone, 2-propanol, 2-butanone and phenol showed significant changes after protein intake. Methanethiol concentrations increased 6-fold within minutes after the protein intake. Optimization of methods and instrument design enabled reliable breath-resolved PTR-MS based analysis of exhaled reactive VOCs in the sub-ppbV range. Continuous in vivo monitoring of exhaled amines and sulphur containing compounds may provide novel non-invasive insight into endogenous and gut bacteria driven protein metabolism.

Can Recognition of Spinal Ischemia Be Improved? Application of Motor-Evoked Potentials, Serum Markers, and Breath Gas Analysis in an Acutely Instrumented Pig Model.

BACKGROUND: Paraplegia due to spinal cord ischemia (SCI) is a serious complication after repair of thoracoabdominal aortic aneurysms. For prevention and early treatment of spinal ischemia, intraoperative monitoring of spinal cord integrity is essential. This study was intended to improve recognition of SCI through a combination of transcranial motor-evoked potentials (tc-MEPs), serum markers, and innovative breath analysis. METHODS: In 9 female German Landrace pigs, tc-MEPs were captured, markers of neuronal damage were determined in blood, and volatile organic compounds (VOCs) were analyzed in exhaled air. After thoraco-phrenico-laparotomy, SCI was initiated through sequential clamping (n = 4) or permanently ligating (n = 5) SAs of the abdominal and thoracic aorta in caudocranial orientation until a drop in the tc-MEPs to at least 25% of the baseline was recorded. VOCs in breath were determined by means of solid-phase microextraction coupled with gas chromatography-mass spectrometry. After waking up, clinical and neurological status was evaluated (Tarlov score). Spinal cord histology was obtained in postmortem. RESULTS: Permanent vessel ligature induced a worse neurological outcome and a higher number of necrotic motor neurons compared to clamping. Changes of serum markers remained unspecific. After laparotomy, exhaled acetone and isopropanol showed highest concentrations, and pentane and hexane increased during ischemia-reperfusion injury. CONCLUSIONS: To mimic spinal ischemia occurring in humans during aortic aneurysm repair, animal models have to be meticulously evaluated concerning vascular anatomy and function. Volatiles from breath indicated metabolic stress during surgery and oxidative damage through ischemia reperfusion. Breath VOCs may provide complimentary information to conventional monitoring methods.

Evaluation of needle trap micro-extraction and solid-phase micro-extraction: Obtaining comprehensive information on volatile emissions from in vitro cultures.

Volatile organic compounds (VOCs) emitted from in vitro cultures may reveal information on species and metabolism. Owing to low nmol L-1 concentration ranges, pre-concentration techniques are required for gas chromatography-mass spectrometry (GC-MS) based analyses. This study was intended to compare the efficiency of established micro-extraction techniques - solid-phase micro-extraction (SPME) and needle-trap micro-extraction (NTME) - for the analysis of complex VOC patterns. For SPME, a 75 µm Carboxen®/polydimethylsiloxane fiber was used. The NTME needle was packed with divinylbenzene, Carbopack X and Carboxen 1000. The headspace was sampled bi-directionally. Seventy-two VOCs were calibrated by reference standard mixtures in the range of 0.041-62.24 nmol L-1 by means of GC-MS. Both pre-concentration methods were applied to profile VOCs from cultures of Mycobacterium avium ssp. paratuberculosis. Limits of detection ranged from 0.004 to 3.93 nmol L-1 (median = 0.030 nmol L-1 ) for NTME and from 0.001 to 5.684 nmol L-1 (median = 0.043 nmol L-1 ) for SPME. NTME showed advantages in assessing polar compounds such as alcohols. SPME showed advantages in reproducibility but disadvantages in sensitivity for N-containing compounds. Micro-extraction techniques such as SPME and NTME are well suited for trace VOC profiling over cultures if the limitations of each technique is taken into account.

Safety and applicability of a pre-stage public access ventilator for trained laypersons: a proof of principle study.

BACKGROUND: Contemporary resuscitation guidelines for basic life support recommend an immediate onset of cardiac compressions in case of cardiac arrest followed by rescue breaths. Effective ventilation is often omitted due to fear of doing harm and fear of infectious diseases. In order to improve ventilation a pre-stage of an automatic respirator was developed for use by laypersons. METHODS: Fifty-two healthy volunteers were ventilated by means of a prototype respirator via a full-face mask in a pilot study. The pre-stage public access ventilator (PAV) consisted of a low-cost self-designed turbine, with sensors for differential pressure, flow, FO2, FCO2 and 3-axis acceleration measurement. Sensor outputs were used to control the respirator and to recognize conditions relevant for efficiency of ventilation and patients' safety. Different respiratory manoeuvres were applied: a) pressure controlled ventilation (PCV), b) PCV with controlled leakage and c) PCV with simulated airway occlusion. Sensor signals were analysed to detect leakage and airway occlusion. Detection based upon sensor signals was compared with evaluation based on clinical observation and additional parameters such as exhaled CO2. RESULTS: Pressure controlled ventilation could be realized in all volunteers. Leakage was recognized with 93.5% sensitivity and 93.5% specificity. Simulated airway occlusion was detected with 91.8% sensitivity and 91.7% specificity. CONCLUSION: The pre-stage PAV was able to detect potential complications relevant for patients' safety such as leakage and airway occlusion in a proof of principle study. Prospectively, this device provides a respectable basis for the development of an automatic emergency respirator and may help to improve bystander resuscitation.

Detection of gaseous compounds by needle trap sampling and direct thermal-desorption photoionization mass spectrometry: concept and demonstrative application to breath gas analysis.

A fast detection method to analyze gaseous organic compounds in complex gas mixtures was developed, using a needle trap device (NTD) in conjunction with thermal-desorption photoionization time-of-flight mass spectrometry (TD-PI-TOFMS). The mass spectrometer was coupled via a deactivated fused silica capillary to an injector of a gas chromatograph. In the hot injector, the analytes collected on the NTD were thermally desorbed and directly transferred to the PI-TOFMS ion source. The molecules are softly ionized either by single photon ionization (SPI, 118 nm) or by resonance enhanced multiphoton ionization (REMPI, 266 nm), and the molecular ion signals are detected in the TOF mass analyzer. Analyte desorption and the subsequent PI-TOFMS detection step only lasts ten seconds. The specific selectivity of REMPI (i.e., aromatic compounds) and universal ionization characteristics render PI-MS as a promising detection system. As a first demonstrative application, the alveolar phase breath gas of healthy, nonsmoking subjects was sampled on NTDs. While smaller organic compounds such as acetone, acetaldehyde, isoprene, or cysteamine can be detected in the breath gas with SPI, REMPI depicts the aromatic substances phenol and indole at 266 nm. In the breath gas of a healthy, smoking male subject, several xenobiotic substances such as benzene, toluene, styrene, and ethylbenzene can be found as well. Furthermore, the NTD-REMPI-TOFMS setup was tested for breath gas taken from a mechanically ventilated pig under continuous intravenous propofol (2,6-diisopropylphenol, narcotic drug) infusion.

Protocol for visualizing complex volatile metabolomics data in clinical setups using EDaViS software.

Here, we present a protocol for using Early Data Visualization Script, a user-friendly software tool to visualize complex volatile metabolomics data in clinical setups. We describe steps for tabulating data and adjusting visual output to visualize complex time-resolved volatile omics data using simple charts and graphs. We then demonstrate possible modifications by detailing procedures for the adaptation of four basic functions. For complete details on the use and execution of this protocol, please refer to Sukul et al. (2022)1 and Remy et al. (2022).2.

Effects of Contagious Respiratory Pathogens on Breath Biomarkers.

Due to their immediate exhalation after generation at the cellular/microbiome levels, exhaled volatile organic compounds (VOCs) may provide real-time information on pathophysiological mechanisms and the host response to infection. In recent years, the metabolic profiling of the most frequent respiratory infections has gained interest as it holds potential for the early, non-invasive detection of pathogens and the monitoring of disease progression and the response to therapy. Using previously unpublished data, randomly selected individuals from a COVID-19 test center were included in the study. Based on multiplex PCR results (non-SARS-CoV-2 respiratory pathogens), the breath profiles of 479 subjects with the presence or absence of flu-like symptoms were obtained using proton-transfer-reaction time-of-flight mass spectrometry. Among 223 individuals, one respiratory pathogen was detected in 171 cases, and more than one pathogen in 52 cases. A total of 256 subjects had negative PCR test results and had no symptoms. The exhaled VOC profiles were affected by the presence of Haemophilus influenzae, Streptococcus pneumoniae, and Rhinovirus. The endogenous ketone, short-chain fatty acid, organosulfur, aldehyde, and terpene concentrations changed, but only a few compounds exhibited concentration changes above inter-individual physiological variations. Based on the VOC origins, the observed concentration changes may be attributed to oxidative stress and antioxidative defense, energy metabolism, systemic microbial immune homeostasis, and inflammation. In contrast to previous studies with pre-selected patient groups, the results of this study demonstrate the broad inter-individual variations in VOC profiles in real-life screening conditions. As no unique infection markers exist, only concentration changes clearly above the mentioned variations can be regarded as indicative of infection or colonization.

Continuous real time breath gas monitoring in the clinical environment by proton-transfer-reaction-time-of-flight-mass spectrometry.

Analysis of volatile organic compounds (VOCs) in breath holds great promise for noninvasive diagnostic applications. However, concentrations of VOCs in breath may change quickly, and actual and previous uptakes of exogenous substances, especially in the clinical environment, represent crucial issues. We therefore adapted proton-transfer-reaction-time-of-flight-mass spectrometry for real time breath analysis in the clinical environment. For reasons of medical safety, a 6 m long heated silcosteel transfer line connected to a sterile mouth piece was used for breath sampling from spontaneously breathing volunteers and mechanically ventilated patients. A time resolution of 200 ms was applied. Breath from mechanically ventilated patients was analyzed immediately after cardiac surgery. Breath from 32 members of staff was analyzed in the post anesthetic care unit (PACU). In parallel, room air was measured continuously over 7 days. Detection limits for breath-resolved real time measurements were in the high pptV/low ppbV range. Assignment of signals to alveolar or inspiratory phases was done automatically by a matlab-based algorithm. Quickly and abruptly occurring changes of patients' clinical status could be monitored in terms of breath-to-breath variations of VOC (e.g. isoprene) concentrations. In the PACU, room air concentrations mirrored occupancy. Exhaled concentrations of sevoflurane strongly depended on background concentrations in all participants. In combination with an optimized inlet system, the high time and mass resolution of PTR-ToF-MS provides optimal conditions to trace quick changes of breath VOC profiles and to assess effects from the clinical environment.

Evaluation of needle trap micro-extraction and automatic alveolar sampling for point-of-care breath analysis.

Needle trap devices (NTDs) have shown many advantages such as improved detection limits, reduced sampling time and volume, improved stability, and reproducibility if compared with other techniques used in breath analysis such as solid-phase extraction and solid-phase micro-extraction. Effects of sampling flow (2-30 ml/min) and volume (10-100 ml) were investigated in dry gas standards containing hydrocarbons, aldehydes, and aromatic compounds and in humid breath samples. NTDs contained (single-bed) polymer packing and (triple-bed) combinations of divinylbenzene/Carbopack X/Carboxen 1000. Substances were desorbed from the NTDs by means of thermal expansion and analyzed by gas chromatography-mass spectrometry. An automated CO2-controlled sampling device for direct alveolar sampling at the point-of-care was developed and tested in pilot experiments. Adsorption efficiency for small volatile organic compounds decreased and breakthrough increased when sampling was done with polymer needles from a water-saturated matrix (breath) instead from dry gas. Humidity did not affect analysis with triple-bed NTDs. These NTDs showed only small dependencies on sampling flow and low breakthrough from 1-5 %. The new sampling device was able to control crucial parameters such as sampling flow and volume. With triple-bed NTDs, substance amounts increased linearly with increasing sample volume when alveolar breath was pre-concentrated automatically. When compared with manual sampling, automatic sampling showed comparable or better results. Thorough control of sampling and adequate choice of adsorption material is mandatory for application of needle trap micro-extraction in vivo. The new CO2-controlled sampling device allows direct alveolar sampling at the point-of-care without the need of any additional sampling, storage, or pre-concentration steps.

Origin of breath isoprene in humans is revealed via multi-omic investigations.

Plants, animals and humans metabolically produce volatile isoprene (C5H8). Humans continuously exhale isoprene and exhaled concentrations differ under various physio-metabolic and pathophysiological conditions. Yet unknown metabolic origin hinders isoprene to reach clinical practice as a biomarker. Screening 2000 individuals from consecutive mass-spectrometric studies, we herein identify five healthy German adults without exhaled isoprene. Whole exome sequencing in these adults reveals only one shared homozygous (European prevalence: <1%) IDI2 stop-gain mutation, which causes losses of enzyme active site and Mg2+-cofactor binding sites. Consequently, the conversion of isopentenyl diphosphate to dimethylallyl diphosphate (DMAPP) as part of the cholesterol metabolism is prevented in these adults. Targeted sequencing depicts that the IDI2 rs1044261 variant (p.Trp144Stop) is heterozygous in isoprene deficient blood-relatives and absent in unrelated isoprene normal adults. Wild-type IDI1 and cholesterol metabolism related serological parameters are normal in all adults. IDI2 determines isoprene production as only DMAPP sources isoprene and unlike plants, humans lack isoprene synthase and its enzyme homologue. Human IDI2 is expressed only in skeletal-myocellular peroxisomes and instant spikes in isoprene exhalation during muscle activity underpins its origin from muscular lipolytic cholesterol metabolism. Our findings translate isoprene as a clinically interpretable breath biomarker towards potential applications in human medicine.

Breath analysis during one-lung ventilation in cancer patients.

Noninvasive breath analysis may provide valuable information for cancer recognition if disease-specific volatile biomarkers could be identified. In order to compare nondiseased and diseased tissue in vivo, this study took advantage of the special circumstances of one-lung ventilation (OLV) during lung-surgery. 15 cancer patients undergoing lung resection with OLV were enrolled. From each patient, alveolar breath samples were taken separately from healthy and diseased lungs before and after tumour resection. Volatile substances were pre-concentrated by means of solid-phase microextraction, and were separated, identified and quantified by means of gas chromatography-mass spectrometry. Different classes of volatile substances could be identified according to their concentration profiles. Due to prolonged fasting and activation of lipolysis, concentrations of endogenous acetone significantly increased during surgery. Exogenous substances, such as benzene or cyclohexanone, showed typical washout exhalation kinetics. Exhaled concentrations of potentially tumour associated substances, such as butane or pentane, were different for nondiseased and diseased lungs and decreased significantly after surgery. Separate analysis of volatile substances exhaled from healthy and diseased lungs in the same patient, together with thorough consideration of substance origins and exhalation kinetics offers unique opportunities of biomarker recognition and evaluation.

Advanced setup for safe breath sampling and patient monitoring under highly infectious conditions in the clinical environment.

Being the proximal matrix, breath offers immediate metabolic outlook of respiratory infections. However, high viral load in exhalations imposes higher transmission risk that needs improved methods for safe and repeatable analysis. Here, we have advanced the state-of-the-art methods for real-time and offline mass-spectrometry based analysis of exhaled volatile organic compounds (VOCs) under SARS-CoV-2 and/or similar respiratory conditions. To reduce infection risk, the general experimental setups for direct and offline breath sampling are modified. Certain mainstream and side-stream viral filters are examined for direct and lab-based applications. Confounders/contributions from filters and optimum operational conditions are assessed. We observed immediate effects of infection safety mandates on breath biomarker profiles. Main-stream filters induced physiological and analytical effects. Side-stream filters caused only systematic analytical effects. Observed substance specific effects partly depended on compound's origin and properties, sampling flow and respiratory rate. For offline samples, storage time, -conditions and -temperature were crucial. Our methods provided repeatable conditions for point-of-care and lab-based breath analysis with low risk of disease transmission. Besides breath VOCs profiling in spontaneously breathing subjects at the screening scenario of COVID-19/similar test centres, our methods and protocols are applicable for moderately/severely ill (even mechanically-ventilated) and highly contagious patients at the intensive care.

Non-Invasive O-Toluidine Monitoring during Regional Anaesthesia with Prilocaine and Detection of Accidental Intravenous Injection in an Animal Model.

Regional anaesthesia is well established as a standard method in clinical practice. Currently, the local anaesthetics of amino-amide types such as prilocaine are frequently used. Despite routine use, complications due to overdose or accidental intravenous injection can arise. A non-invasive method that can indicate such complications early would be desirable. Breath gas analysis offers great potential for the non-invasive monitoring of drugs and their volatile metabolites. The physicochemical properties of o-toluidine, the main metabolite of prilocaine, allow its detection in breath gas. Within this study, we investigated whether o-toluidine can be monitored in exhaled breath during regional anaesthesia in an animal model, if correlations between o-toluidine and prilocaine blood levels exist and if accidental intravenous injections are detectable by o-toluidine breath monitoring. Continuous o-toluidine monitoring was possible during regional anaesthesia of the cervical plexus and during simulated accidental intravenous injection of prilocaine. The time course of exhaled o-toluidine concentrations considerably differed depending on the injection site. Intravenous injection led to an immediate increase in exhaled o-toluidine concentrations within 2 min, earlier peak and higher maximum concentrations, followed by a faster decay compared to regional anaesthesia. The strength of correlation of blood and breath parameters depended on the injection site. In conclusion, real time monitoring of o-toluidine in breath gas is possible by means of PTR-ToF-MS. Since simulated accidental intravenous injection led to an immediate increase in exhaled o-toluidine concentrations within 2 min and higher maximum concentrations, monitoring exhaled o-toluidine may potentially be applied for the non-invasive real-time detection of accidental intravenous injection of prilocaine.

Real-time metabolic monitoring under exhaustive exercise and evaluation of ventilatory threshold by breathomics: Independent validation of evidence and advances.

Breath analysis was coupled with ergo-spirometry for non-invasive profiling of physio-metabolic status under exhaustive exercise. Real-time mass-spectrometry based continuous analysis of exhaled metabolites along with breath-resolved spirometry and heart rate monitoring were executed while 14 healthy adults performed ergometric ramp exercise protocol until exhaustion. Arterial blood lactate level was analyzed at defined time points. Respiratory-cardiac parameters and exhalation of several blood-borne volatiles changed continuously with the course of exercise and increasing workloads. Exhaled volatiles mirrored ventilatory and/or hemodynamic effects and depended on the origin and/or physicochemical properties of the substances. At the maximum workload, endogenous isoprene, methanethiol, dimethylsulfide, acetaldehyde, butanal, butyric acid and acetone concentrations decreased significantly by 74, 25, 35, 46, 21, 2 and 2%, respectively. Observed trends in exogenous cyclohexadiene and acetonitrile mimicked isoprene profile due to their similar solubility and volatility. Assignment of anaerobic threshold was possible via breath acetone. Breathomics enabled instant profiling of physio-metabolic effects and anaerobic thresholds during exercise. Profiles of exhaled volatiles indicated effects from muscular vasoconstriction, compartmental distribution of perfusion, extra-alveolar gas-exchange and energy homeostasis. Sulfur containing compounds and butyric acid turned out to be interesting for investigations of combined diet and exercise programs. Reproducible metabolic breath patterns have enhanced scopes of breathomics in sports science/medicine.

Profiling of exhaled volatile organics in the screening scenario of a COVID-19 test center.

Breath volatile organics (VOCs) may provide immediate information on infection mechanisms and host response. We conducted real-time mass spectrometry-based breath profiling in 708 non-preselected consecutive subjects in the screening scenario of a COVID-19 test center. Recruited subjects were grouped based on PCR-confirmed infection status and presence or absence of flu-like symptoms. Exhaled VOC profiles of SARS-CoV-2-positive cases (n = 36) differed from healthy (n = 256) and those with other respiratory infections (n = 416). Concentrations of most VOCs were suppressed in COVID-19. VOC concentrations also differed between symptomatic and asymptomatic cases. Breath markers mirror effects of infections onto host's cellular metabolism and microbiome. Downregulation of specific VOCs was attributed to suppressive effects of SARS-CoV-2 onto gut or pulmonary microbial metabolism. Breath analysis holds potential for monitoring SARS-CoV-2 infections rather than for primary diagnosis. Breath profiling offers unconventional insight into host-virus cross-talk and infection microbiology and enables non-invasive assessment of disease manifestation.

Physiological and metabolic effects of healthy female aging on exhaled breath biomarkers.

Healthy aging driven physio-metabolic events in females hold the key to complex in vivo mechanistic links and systemic cross talks. Effects from basic changes at genome, proteome, metabolome, and lipidome levels are often reflected at the upstream phenome (e.g., breath volatome) cascades. Here, we have analyzed exhaled volatile metabolites (measured via real time mass spectrometry based breathomics) data from 204 healthy females, aged between 07 and 80 years. Age related substance-specific differences were observed in breath biomarkers. Exhalation of blood-borne endogenous organosulfur, short-chain fatty acids, alcohols, aldehydes, alkene, ketones and exogenous nitriles, terpenes, and aromatics have denominated interplay between endocrine differences, energy homeostasis, systemic microbial diversity, oxidative stress, and lifestyle. Overall marker expressions were suppressed under daily oral contraception. Young homosexual/lesbian adults turned out as breathomic outliers. Previously proposed disease-specific breath biomarkers should be reevaluated upon aging effects. Breathomics offers a noninvasive window toward system-wide understanding and personalized monitoring of aging i.e., translatable to gerontology.

Phase-resolved real-time breath analysis during exercise by means of smart processing of PTR-MS data.

Separation of inspiratory, mixed expired and alveolar air is indispensable for reliable analysis of VOC breath biomarkers. Time resolution of direct mass spectrometers often is not sufficient to reliably resolve the phases of a breathing cycle. To realise fast on-line breath monitoring by means of direct MS utilising low-fragmentation soft ionisation, a data processing algorithm was developed to identify inspiratory and alveolar phases from MS data without any additional equipment. To test the algorithm selected breath biomarkers (acetone, isoprene, acetaldehyde and hexanal) were determined by means of quadrupole proton transfer reaction mass spectrometry (PTR-MS) in seven healthy volunteers during exercise on a stationary bicycle. The results were compared to an off-line reference method consisting of controlled alveolar breath sampling in Tedlar® bags, preconcentration by solid-phase micro extraction (SPME), separation and identification by GC-MS. Based on the data processing method, quantitative attribution of biomarkers to inspiratory, alveolar and mixed expiratory phases was possible at any time during the experiment, even under respiratory rates up to 60/min. Alveolar concentrations of the breath markers, measured by PTR-MS ranged from 130 to 2,600 ppb (acetone), 10 to 540 ppb (isoprene), 2 to 31 ppb (acetaldehyde), whereas the concentrations of hexanal were always below the limit of detection (LOD) of 3 ppb. There was good correlation between on-line PTR-MS and SPME-GC-MS measurements during phases with stable physiological parameters but results diverged during rapid changes of heart rate and minute ventilation. This clearly demonstrates the benefits of breath-resolved MS for fast on-line monitoring of exhaled VOCs.