Abstract: A system for positioning a catheter in the left bronchus of a patient, who is undergoing a medical procedure with an endotracheal tube to control the patient's breathing. The catheter tube is shaped in a concave curve and is semi-rigid and capable of being biased. The endotracheal tube is shaped in a concave curve in a plane generally aligned in the left-right bisecting plane of the body of the patient. A bronchial curved portion of the catheter extends outwardly from the bottom area of the catheter tube at an angle from the bisecting plane toward the left bronchus. The curved catheter aligns with the curvature of the endotracheal tube during the insertion process and the bronchial curved portion automatically aligns with the left main-stem bronchus. Further insertion results in the final positioning of the distal end of the catheter in the left bronchus. The catheter can be used for either evacuation of mucous or for the injection of a fluid, such as a mucous thinner.