Respiratory tract deposition of smoke particles using a nasal bypass device

In order to avoid nasal absorption, an intralaryngeal cannula was tested as a device for bypassing the nose in delivering smoke into the lungs of hamsters. The intralaryngeal cannula increased lung deposition of radiolabeled smoke particles twofold to threefold over that in nose-breathing controls. Stabilization of respiration (absence of avoidance reaction), rather than prevention of nasal absorption of smoke, was demonstrated to be the cannula's major mechanism of action. Although suitable for acute exposures, the device is of limited use for chronic exposures that require daily insertion of the cannula during an extended period of time.