Trace gases on the breath of healthy volunteers when fasting and following a protein calorie meal: a preliminary study. Smith, David, Patrik Spanel and Simon Davies. 1 Centre for Science and Technology in Medicine, School of Postgraduate Medicine, Keele University, UK; 2 J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Czech Republic; and 3 Department of Medicine, School of Postgraduate Medicine, Keele University, UK
APStracts 6:0244A, 1999.
The Selected Ion Flow Tube technique was used to quantify in breath the trace gases acetone, ammonia, ethanol, isoprene and methanol during single exhalations whilst fasting and in response to feeding. Six normal volunteers were fasted for twelve hours, and after obtaining baseline breath samples, were fed a liquid protein-calorie meal, to provide 0.47 g/kg of protein (Fortisip (). Further breath samples were obtained at 20, 40 and 60 minutes, and then hourly for a further five hours. Breath acetone concentrations fell from a maximum during fasting, reaching their nadir between four and five hours. Breath ammonia concentrations fell immediately to half their fasting levels prior to a steady increase to two or three times baseline values at five hours. There was a brief increase in breath ethanol concentrations following feeding, reflecting detectable ethanol contamination of the feed. Subsequently breath ethanol levels remained low throughout the experimental protocol. Isoprene concentrations did not change significantly, whereas changes in methanol concentrations reflected those in the ambient air. This preliminary study indicates that the SIFT technique may be used to detect changes in the trace gases present in breath, and define their concentrations in the fasting and replete state. Of particular interest is the biphasic response of the breath ammonia concentration following feeding. 

Received 30 October 1998; accepted in final form 25 May 1999.
APS Manuscript Number A989-8.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 14 June 1999