Patent ID: 8399837
Filing Date: 2013-03-19
Classification: A61B,A61M,G01N

Abstract:
1. Apparatus for measuring respiratory oxygen consumption in the breath of a human or animal subject, comprising: a breathing tube for provision in an airway for the subject, an absorption spectrometer for measuring the concentration of molecular oxygen in gas passing through the breathing tube; a flow meter for measuring the rate of flow of gas through the breathing tube; and a processor for receiving the concentration and flow rate measurements and adapted to calculate from them and to output breath-by-breath measurements of oxygen consumption; wherein the absorption spectrometer comprises: an optical cavity disposed in the breathing tube in proximity to the subject and through which said gas passes, a light source for supplying light to the optical cavity and a light detector for detecting light emerging from the optical cavity, thereby to provide a signal representative of the absorption of the light by molecular oxygen in the gas in the optical cavity, and wherein the optical cavity and light source are arranged such that the light in the optical cavity retraces some or all of its path to excite one or more resonant modes in the optical cavity to provide cavity enhancement of the oxygen absorption signal.