Handpiece for Respiratory Monitor

A device for use with a respiratory monitor is disclosed that includes features for collecting and guiding a breath gas sample from a user. The device includes a breath intake structure connected to a handheld body structure. The breath intake structure may include one or more permeable membranes to filter particular substances, such as bacteria, viruses, and microbes, from the breath gas sample before it proceeds through the body structure. The device further includes one or more pre-conditioning elements that pretreats the breath gas sample before it enters a respiratory monitor. In some embodiments, the device may include a mouthpiece and body that are used to collect and guide a breath gas sample to a nitric oxide detection device. Moisture is removed from the breath gas sample using a desiccant loaded into a pre-conditioning cartridge. The mouthpiece may be removably connected to the body and disposable. Interchangeable pre-conditioning cartridges may allow use of different cartridges and different pre-conditioning materials with the device.