An endotracheal tube apparatus is provided which comprises an endotracheal tube insertable into a trachea of a patient, wherein the endotracheal tube has a sidewall and includes a first passageway, wherein the first passageway is a ventilation passageway to provide ventilation to the patient; a fluid sampling port connected to the sidewall of the endotracheal tube; the fluid sampling port including a fluid sampling passageway, the fluid sampling passageway to obtain a fluid sample comprising one or more gases exhaled from the patient; and the fluid sampling port including a connector to connect the fluid sampling port to an analyzer to detect a presence of carbon dioxide gas in the fluid sample.