Real-time monitoring of breath ammonia during haemodialysis: use of ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques

The diffusion of high-performance analytical technology has opened prospects for breath diagnosis as a non-invasive diagnostic tool. In this study, ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques were used to analyse ammonia gas (NH3) in real-time in breath from patients undergoing haemodialysis (HD) treatment and any correlation with blood urea nitrogen (BUN) levels and Kt/V were investigated. We studied 20 patients on intermittent HD treatment. The first breath samples were taken before the start of dialysis and further breath samples were taken every hour during the treatment and after the end of the session. An evaluation was also made of 20 healthy volunteers, acting as controls [healthy subjects (HS)]. Breath ammonia concentrations were higher in CRDS-HD (914.5±301.4 versus 280±120 parts per billion (p.p.b.), P