Patent ID: 8312878

Claim:
A mainstream gas monitoring system comprising: (a) a mainstream airway adapter; and (b) a gas sensing assembly associated with the mainstream airway adapter and comprising: (1) a gas sensing portion associated with the mainstream airway adapter, wherein the gas sensing portion outputs a signal indicative of an analyte in a gas flow in the mainstream airway adapter, and (2) a processing portion adapted to receive the signal from the gas sensing portion, wherein the processing portion is programmed to determine an amount of the analyte in the gas flow based on the signal from the gas sensing portion, and wherein the processing portion is programmed to compensate for volumetric differences between the gas flow during inspiration and the gas flow during expiration, wherein the processing portion compensates for the volumetric differences by monitoring a tracheal dead space gas and using the monitored tracheal dead space gas to determine the amount of the analyte in the gas flow, and wherein the monitored tracheal dead space gas comprises a first portion of gas exhaled during the expiration.