Non-invasive monitoring of breath ammonia and trimethylamine using Selected-ion-flow-tube mass spectroscopy (SIFT-MS) could provide a real-time alternative to current invasive techniques. Breath ammonia and trimethylamine were monitored by SIFT-MS before, during and after haemodialysis in 20 patients. In 15 patients (41 sessions), breath was collected hourly into Tedlar bags and analysed immediately (group A). During multiple dialyses over 8 days, five patients breathed directly into the SIFT-MS analyser every 30 min (group B). Pre- and post-dialysis direct breath concentrations were compared with urea reduction, Kt/V and creatinine concentrations. Dialysis decreased breath ammonia, but a transient increase occurred mid treatment in some patients. Trimethylamine decreased more rapidly than reported previously. Pre-dialysis breath ammonia correlated with pre-dialysis urea in group B (r(2) = 0.71) and with change in urea (group A, r(2) = 0.24; group B, r(2) = 0.74). In group B, ammonia correlated with change in creatinine (r(2) = 0.35), weight (r(2) = 0.52) and Kt/V (r(2) = 0.30). The ammonia reduction ratio correlated with the urea reduction ratio (URR) (r(2) = 0.42) and Kt/V (r(2) = 0.38). Pre-dialysis trimethylamine correlated with Kt/V (r(2) = 0.21), and the trimethylamine reduction ratio with URR (r(2) = 0.49) and Kt/V (r(2) = 0.36). Real-time breath analysis revealed previously unmeasurable differences in clearance kinetics of ammonia and trimethylamine. Breath ammonia is potentially useful in assessment of dialysis efficacy.

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Selected ion flow tube-mass spectrometry (SIFT-MS) can measure volatile compounds in breath on-line in real time and has the potential to provide accurate breath tests for a number of inflammatory, infectious and metabolic diseases, including diabetes. Breath concentrations of acetone in type 2 diabetic subjects undertaking a long-term dietary modification programme were studied. Acetone concentrations in the breath of 38 subjects with type 2 diabetes were determined by SIFT-MS. Anthropomorphic measurements, dietary intake and medication use were recorded. Blood was analysed for beta hydroxybutyrate (a ketone body), HbA1c (glycated haemoglobin) and glucose using point-of-care capillary (fingerprick) testing. All subjects were able to undertake breath manoeuvres suitable for analysis. Breath acetone varied between 160 and 862 ppb (median 337 ppb) and was significantly higher in men (median 480 ppb versus 296 ppb, p = 0.01). In this cross-sectional study, no association was observed between breath acetone and either dietary macronutrients or point-of-care capillary blood tests. Breath analysis by SIFT-MS offers a rapid, reproducible and easily performed measurement of acetone concentration in ambulatory patients with type 2 diabetes. The high inter-individual variability in breath acetone concentration may limit its usefulness in cross-sectional studies. Breath acetone may nevertheless be useful for monitoring metabolic changes in longitudinal metabolic studies, in a variety of clinical and research settings.

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For the 2009 influenza A (H1N1) pandemic, vaccination and infection control were the main modes of prevention. A live attenuated H1N1 vaccine mimics natural infection and works by evoking a host immune response, but currently there are no easy methods to measure such a response. To determine if an immune response could be measured in exhaled breath, exhaled nitric oxide (FENO) and other exhaled breath volatiles using selected ion flow tube mass spectrometry (SIFT-MS) were measured before and daily for seven days after administering the H1N1 2009 monovalent live intranasal vaccine (FluMist®, MedImmune LLC) in nine healthy healthcare workers (age 35 ± 7 years; five females). On day 3 after H1N1 FluMist® administration there were increases in FENO (MEAN±SEM: day 0 15 ± 3 ppb, day 3 19 ± 3 ppb; p < 0.001) and breath isoprene (MEAN±SEM: day 0 59 ± 15 ppb, day 3 99 ± 17 ppb; p = 0.02). MS analysis identified the greatest number of changes in exhaled breath on day 3 with 137 product ion masses that changed from baseline. The exhaled breath changes on day 3 after H1N1 vaccination may reflect the underlying host immune response. However, further work to elucidate the sources of the exhaled breath changes is necessary.