A device for the treatment of pneumothorax especially in neonates, which facilitates the simple one-hand introduction of a catheter-sheathed stylet through the chest wall and which contains a one-way valve outside the chest for the stat evacuation of the intrathoracic air or fluid. The device is capable of secure fixation to the chest wall until deemed no longer needed at which point it is quickly removable. The thoracic cavity is entered by a stylet which is surrounded by a catheter, the catheter lumen continuous with that of a lumenized dome which communicates with at least one upper port and one-way valving. One port is configured to allow Luer-Lok suction in the event of pleural effusion or hemothorax.