Congenital tracheal stenosis is a rare life-threatening obstruction in infancy and childhood. Symptoms are ranged from recurrent stridor and wheezing to severe respiratory compromise and hypercarbia. If the patient with tracheal stenosis, who has hypercarbia, is hyperventilated to maintain normocarbia, air is trapped in the lung and the risk of pulmonary barotrauma is increased. Cardiopulmonary-bypass is recommended for this patient to have corrective surgery. Permissive hypercapnia is proposed for the mechanical ventilation of patients with severe tracheal stenosis before cardiopulmonary-bypass.