A device for use in delivering oxygen to a human patient while measuring carbon dioxide exhaled from that patient, comprises: (a) a base member having an oxygen delivery inlet port and a carbon dioxide detection outlet port formed therein separate from the oxygen delivery port； (b) a flexible cannula extending from the base, the cannula having a proximal end portion, an intermediate portion, a distal end portion, a first lumen formed therein, and a second lumen separate from the first lumen formed therein, with the distal end portion connected to the base member, the first lumen in fluid communication with the oxygen delivery inlet port, and the second lumen in fluid communication with the carbon dioxide detection outlet port.
