title: Breath ammonia and trimethylamine allow real-time monitoring of haemodialysis efficacy.
abstract: 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.
authors.affiliation: Christchurch Kidney Research Group, Department of Medicine, University of Otago, Christchurch, New Zealand.
authors.forename: Z H
authors.initials: ZH
authors.lastname: Endre
authors.forename: J W
authors.initials: JW
authors.lastname: Pickering
authors.forename: M K
authors.initials: MK
authors.lastname: Storer
authors.forename: W-P
authors.initials: WP
authors.lastname: Hu
authors.forename: K T
authors.initials: KT
authors.lastname: Moorhead
authors.forename: R
authors.initials: R
authors.lastname: Allardyce
authors.forename: D O
authors.initials: DO
authors.lastname: McGregor
authors.forename: J M
authors.initials: JM
authors.lastname: Scotter
mesh_terms: D000096:Acetone / Q000032:analysis; D000328:Adult; D000368:Aged; D000641:Ammonia / Q000032:analysis*; D001944:Breath Tests / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008744:Methylamines / Q000032:analysis*; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D012015:Reference Standards; D006435:Renal Dialysis / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D008744:Methylamines; D000096:Acetone; D000641:Ammonia; C023336:trimethylamine