A switchable device for closed suction catheters includes a device body and a two-way switch valve. The device body is formed with a valve sleeve, a patient tubing adaptor, a side port, and a catheter adaptor. The valve sleeve is formed with a cavity therein to allow the two-way switch valve to correspondingly rotate with respect to the device body. The catheter adaptor and the patient tubing adaptor are formed on opposing ends of the valve sleeve, thereby able to establish an unobstructed path therebetween. The side port is slantingly formed and extended from the patient tubing adaptor for smooth passage of flow therebetween. A groove is formed on one end of the patient tubing adaptor as a 360-degree freely rotatable coupling element thereof.
