An endotracheal device configured for insertion through a tracheal passage to the bronchial bifurcation, the endotracheal device comprising a tube extending between a proximal end and a distal end, wherein the distal end of the endotracheal device is configured for placement proximate the bronchial bifurcation, the endotracheal device further comprising: a first lumen extending through the tube of the endotracheal device, the first lumen extending from a first internal port to a first external port, wherein the first external port is proximate the proximal end of the endotracheal device and configured for attachment to a gas transfer apparatus, wherein the first external port is positioned outside of the tracheal passage when the first internal port is positioned proximate the bronchial bifurcation; a second lumen extending through the tube of the endotracheal device, the second lumen extending from a second internal port to a second external port, wherein the second external port is proximate the proximal end of the endotracheal device and configured for attachment to a gas transfer apparatus, wherein the second external port is positioned outside of the tracheal passage when the second internal port is positioned proximate the bronchial bifurcation; and insulation located in an interior of the tube of the endotracheal device, the insulation being located between the first lumen and the second lumen to limit thermal energy transfer between fluids located in the first and second lumens; wherein the first lumen is separate and independent of the second lumen such that gas passing through the first lumen cannot enter the second lumen between the first external port and the first internal port; characterized in that the first lumen comprises a first one-way valve configured to allow inspiratory flow through the first lumen from the first external port to and out of the first internal port and limit expiratory flow through the first lumen from the first internal port to and out of the first external port, wherein the first one-way valve is located in the first lumen closer to the first internal port than the first external port. a first lumen extending through the tube of the endotracheal device, the first lumen extending from a first internal port to a first external port, wherein the first external port is proximate the proximal end of the endotracheal device and configured for attachment to a gas transfer apparatus, wherein the first external port is positioned outside of the tracheal passage when the first internal port is positioned proximate the bronchial bifurcation; a second lumen extending through the tube of the endotracheal device, the second lumen extending from a second internal port to a second external port, wherein the second external port is proximate the proximal end of the endotracheal device and configured for attachment to a gas transfer apparatus, wherein the second external port is positioned outside of the tracheal passage when the second internal port is positioned proximate the bronchial bifurcation; and insulation located in an interior of the tube of the endotracheal device, the insulation being located between the first lumen and the second lumen to limit thermal energy transfer between fluids located in the first and second lumens; wherein the first lumen is separate and independent of the second lumen such that gas passing through the first lumen cannot enter the second lumen between the first external port and the first internal port; characterized in that the first lumen comprises a first one-way valve configured to allow inspiratory flow through the first lumen from the first external port to and out of the first internal port and limit expiratory flow through the first lumen from the first internal port to and out of the first external port, wherein the first one-way valve is located in the first lumen closer to the first internal port than the first external port.