A sensor adaptor couples a face mask to a gas sampling tube connected to a device detecting end-tidal carbon dioxide. The sensor adaptor includes a shaft and connector. The shaft includes a channel providing a pathway for the carbon dioxide to travel toward the gas sampling tube. One end of the shaft includes an adaptor tip which extends through an exit port of the face mask. A connector is attached to the other end of the shaft and couples the sensor adaptor to the gas sampling line. A gripper may surround the shaft and prevent improper advancement of the shaft into the face mask. The sensor adaptor can be designed for use with any gas sampling tube and any face mask including exit ports.