Exhaled breath acetone (BrAce) was investigated during and after submaximal aerobic exercise as a volatile biomarker for metabolic responsiveness in high and lower-fit individuals in a prospective cohort pilot-study. Twenty healthy adults (19–39 years) with different levels of cardiorespiratory fitness (VO2peak), determined by spiroergometry, were recruited. BrAce was repeatedly measured by proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) during 40–55 min submaximal cycling exercise and a post-exercise period of 180 min. Activity of ketone and fat metabolism during and after exercise were assessed by indirect calorimetric calculation of fat oxidation rate and by measurement of venous β-hydroxybutyrate (βHB). Maximum BrAce ratios were significantly higher during exercise in the high-fit individuals compared to the lower-fit group (t-test; p= 0.03). Multivariate regression showed 0.4% (95%-CI = −0.2%–0.9%, p= 0.155) higher BrAce change during exercise for every ml kg−1 min−1 higher VO2peak. Differences of BrAce ratios during exercise were similar to fat oxidation rate changes, but without association to respiratory minute volume. Furthermore, the high-fit group showed higher maximum BrAce increase rates (46% h−1) in the late post-exercise phase compared to the lower-fit group (29% h−1). As a result, high-fit young, healthy individuals have a higher increase in BrAce concentrations related to submaximal exercise than lower-fit subjects, indicating a stronger exercise-related activation of fat metabolism.
Methanol poisoning outbreaks after consumption of adulterated alcohol frequently overwhelm health care facilities in developing countries. Here, we present how a recently developed low-cost and handheld breath detector can serve as a noninvasive and rapid diagnostic tool for methanol poisoning. The detector combines a separation column and a micromachined chemoresistive gas sensor fully integrated into a device that communicates wirelessly with a smartphone. The performance of the detector is validated with methanol-spiked breath of 20 volunteers (105 breath samples) after consumption of alcoholic beverages. Breath methanol concentrations were quantified accurately within 2 min in the full breath-relevant range (10− 1000 ppm) in excellent agreement (R 2 = 0.966) with benchtop mass spectrometry. Bland−Altman analysis revealed sufficient limits of agreement (95% confidence intervals), promising to indicate reliably the clinical need for antidote and hemodialysis treatment. This simple-in-use detector features high diagnostic capability for accurate measurement of methanol in spiked breath, promising for rapid screening of methanol poisoning and assessment of severity. It can be applied readily by first responders to distinguish methanol from ethanol poisoning and monitor in real time the subsequent hospital treatment.
Mobile health technologies can provide information routinely and on demand to manage metabolic diseases (e.g., diabetes and obesity) and optimize their treatment (e.g., exercise or dieting). Most promising is breath acetone monitoring to track lipolysis and complement standard glucose monitoring. Yet, accurate quantification of acetone down to parts‐per‐billion (ppb) is difficult with compact and mobile devices in the presence of interferants at comparable or higher concentrations. Herein, a low‐cost detector that quantifies end‐tidal acetone during exercise and rest is presented with excellent bias (25 ppb) and unprecedented precision (169 ppb) in 146 breath samples. It combines a flame‐made Pt/Al2O3 catalyst with a chemoresistive Si/WO3 sensor. The detector is robust against orders of magnitude higher ethanol concentrations from disinfection and exercise‐driven endogenous breath isoprene ones, as validated by mass spectrometry. This detector accurately tracks the individual lipolysis dynamics in all volunteers, as confirmed by blood ketone measurements. It can be integrated readily into handheld devices for personalized metabolic assessment at home, in gyms, and clinics.
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