There is experimental evidence that volatile substances in human breath can reflect presence of neoplasma. Volatile aldehydes were determined in exhaled breath of 12 lung cancer patients, 12 smokers and 12 healthy volunteers. Alveolar breath samples were collected under control of expired CO 2 . Reactive aldehydes were transformed into stable oximes by means of on-fiber-derivatization (SPME-OFD). Aldehyde concentrations in the ppt and ppb level were determined by means of gas chromatography-mass spectrometry (GC-MS). Exhaled concentrations were corrected for inspired values. Exhaled C 1 -C 10 aldehydes could be detected in all healthy volunteers, smokers and lung cancer patients. Concentrations ranged from 7 pmol/ l (161 pptV) for butanal to 71 nmol/l (1,582 ppbV) for formaldehyde. Highest inspired concentrations were found for formaldehyde and acetaldehyde (0-55 nmol/l and 0-13 nmol/l, respectively). Acetaldehyde, propanal, butanal, heptanal and decanal concentrations showed no significant differences for cancer patients, smokers and healthy volunteers. Exhaled pentanal, hexanal, octanal and nonanal concentrations were significantly higher in lung cancer patients than in smokers and healthy controls (p pentanal 5 0.001; p hexanal 5 0.006; p octanal 5 0.014; p nonanal 5 0.025). Sensitivity and specificity of this method were comparable to the diagnostic certitude of conventional serum markers and CT imaging. Lung cancer patients could be identified by means of exhaled pentanal, hexanal, octanal and nonanal concentrations. Exhaled aldehydes reflect aspects of oxidative stress and tumor-specific tissue composition and metabolism. Noninvasive recognition of lung malignancies may be realized if analytical skills, biochemical knowledge and medical expertise are combined into a joint effort.

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This study was intended to evaluate low-volume (20 mL) multibed needle trap (NTD) sampling combined with heart-cut gas chromatography/mass spectrometry (GC/MS) and comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOF-MS) for trace gas analysis under clinical conditions. NTDs, high-throughput automatic desorption and separation systems, were tested in vitro and within a study in 11 patients undergoing cardiac surgery with respect to reproducibility, reliability, and clinical applicability. NTD-heart-cut GC/MS analysis of standard mixtures containing different volatile organic compounds (VOCs) yielded relative standard deviations (RSDs) from 4.0% to 18.5%. Substance adsorption was stable for 1 day if NTDs were closed on both ends and was stable for approximately 7.8 h when NTD tip ends had to be left open during autosampler storage. Even in the presence of high concentrations of contaminants linearity of heart-cut GC/MS was conserved. In patients' breath potential biomarkers could be determined even in the presence of very high concentrations of sevoflurane. Profiles of blood-borne biomarkers, intravenous drugs, and clinical contaminants were characterized. Comprehensive GC x GC/TOF-MS may be used as a screening tool for new biomarkers, if patterns are generated from deconvoluted normalized areas. Needle trap sampling in combination with hyphenated chromatographic techniques can thus be used to provide well-tailored solutions for complex problems occurring in clinical breath analysis.

BackgroundWhile 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.MethodsWe continuously monitored exhaled breath profiles within mask space in older (age: 60–80 years) and young to mid-aged (age: 20–60 years) adults over the period of 15 and 30 min, respectively by high-resolution real-time mass-spectrometry (PTR-ToF-MS). Peripheral oxygen saturation, respiratory- and haemodynamic parameters were measured (non-invasively) simultaneously.ResultsProfound, consistent and significant (p-value≤0.001) changes in SpO2 (Adults>60_FFP2-15 min: 5.8±1.3%↓, Adults>60_surgical-15 min: 3.6±0.9%↓, Adults<60_FFP2-30 min: 1.9±1.0%↓, Adults<60_surgical-30 min: 0.9±0.6%↓) and pET-CO2 (Adults>60_FFP2-15 min: 19.1±8.0%↑, Adults>60_surgical-15 min: 11.6±7.6%↑, Adults<60_FFP2- 30 min: 12.1±4.5%↑, Adults<60_surgical- 30 min: 9.3±4.1%↑) indicate ascending deoxygenation and hypercarbia. Secondary changes (p-value≤0.005) to hemodynamic parameters (e.g. MAP: Adults>60_FFP2-15 min: 9.8±10.4%↑) were found. Exhalation of blood-borne volatile metabolites e.g. aldehydes, hemiterpene, organosulfur, short-chain fatty acids, alcohols, ketone, aromatics, nitrile and monoterpene mirrored behaviour of cardiac output, MAP, SpO2, respiratory rate and pET-CO2. Exhaled humidity (e.g. Adults>60_FFP2-15 min: 7.1±5.8%↑) and exhaled oxygen (e.g. Adults>60_FFP2-15 min: 6.1±10.0%↓) changed significantly (p-value≤0.005) over time.ConclusionsBreathomics allows unique physio-metabolic 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 hypoxemia, oxidative stress, hypercarbia, vasoconstriction, altered systemic microbial activity, energy homeostasis, compartmental storage and washout. FFP2 masks affected more pronouncedly 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.