2665785 ETCO end-tidal carbon monoxide 7 2665780 ETCO early total cervix occlusion 5 2665783 ETCO end-tidal CO 5 2665781 ETCO end tidal breath CO 2 2665787 ETCO early TCO 1 2665782 ETCO end tidal breath carbon monoxide 1 2665784 ETCO end-tidal breath CO measurements 1 2665786 ETCO end-tidal carbon monoxide concentration 1 2665778 ETCO end-tidal sample of CO 1 2665779 ETCO ethoxycoumarin-O-deethylase 1