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.

Ammonia in breath and emitted from skin

“…Some groups have obtained a slightly higher median concentration [15,18,21,35], whereas others have measured considerably lower values [5,23,25,28,36,40]. However, as should be clear by now, such comparisons can be misleading because the same instrumental NH 3 reading can be obtained for significantly different original eNH 3 concentrations, depending on the prevailing sampling and measurement procedures.…”

The SIFT and FALP techniques; applications to ionic and electronic reactions studies and their evolution to the SIFT-MS and FA-MS analytical methods

“…The SIFT-MS instruments have been exploited in several laboratories for the analysis of a wide variety of complex gaseous media and vapours, the Voice 200 in New Zealand [127][128][129] and Ohio [130,131], and the Profile 3 in the Open University, UK [132] and Imperial College London [133]. This is indicated in Table1 and for more details see [36,47,134].…”

Gases as Uremic Toxins: Is There Something in the Air?

“…10 Ammonia (NH 3 ) has been detected as one of the compounds underlying this specific odor and assessment of ammonia concentrations in the breath has been postulated to be a possible tool to monitor the efficacy of hemodialysis. [12][13][14] Moreover, it has been shown that breath ammonia is correlated with blood urea nitrogen and creatinine levels and it was concluded that breath ammonia measurements could be used as a surrogate measure of the retention status of patients with renal failure. 12,15 Ammonia, a colorless gas, is a product of protein catabolism.…”

“…17 Breath ammonia concentrations have been found to be correlated positively to blood urea levels in cyclic automated peritoneal dialysis and hemodialysis patients. 10,14 A recent study showed that ammonia concentrations in the breath also are increased in chronic renal failure not requiring dialysis. 18 In 1977, Simenhoff et al 17 already found that, apart from ammonia, trimethylamine (TMA) and dimethylamine (DMA) underlie the fishy odor in uremia.…”

“…17 This finding has been confirmed repeatedly. 14,20 Interestingly, DMA is the major metabolite of asymmetric dimethylarginine (ADMA) in the urine. ADMA is produced after the catabolism of proteins containing methylated arginine residues and is metabolized by the enzyme dimethylarginine dimethylaminohydrolase, yielding DMA and citrulline.…”