Abstract: An optical fluid analyzer uses the extent of optical, preferably infrared absorption of a fluid to be analyzed to determine the concentration of a selected constituant of the fluid. A first detector detects light after absorption by the fluid at a wavelength at which the selected constituant has a characteristic absorption for conversion into an electrical signal indicating the concentration of the selected constituant and a background from absorption of other constituants of the fluid for a measurement processing channel. A second detector correspondingly converts light after absorption by the fluid, but at a different wavelength at which the absorption at least approximates the background absorption alone for a neutral processing channel.

Abstract: A gas sampling device has a gas-entry passage dimensioned to provide laminar flow to the gas and opening into a larger gas-receiving passage. A gas sampling tube is supported from the larger gas-receiving passage, extends only to the smaller gas-entry passage for sampling the entering gas, and is coaxially spaced from the walls of the gas-entry passage to sample the gas in the gas-entry passage without dilution from the gas-receiving passage or interference with the gas flow. The device is particularly useful for sampling small exhaled breath gas flow in combination with neonatal respiratory apparatus for sampling the breath of neonates.