Endoscopy Air / Water Suction Valve

Blue Air/Water valve: This is used to control the insufflation of air or flush water to clear the lens. Covering its opening or partial depression feeds air from the distal tip. Full depression flushes water to clear the lens.

Red suction valve: When depressed this aspirates air or fluid through the distal tip. This is connected to the accessory channel. A biopsy cap needs to be in situ covering the accessory channel for the endoscope to generate the suction needed.

An air pump in the light source provides air under mild pressure to a pipe protruding from the light source connector of the endoscope. This air is carried by an air channel (tube) to the air/water valve on the control section. If this valve is not covered, the air simply exits from a vent hole in the top of the valve. This vent hole allows the air pump to pump freely when air is not needed, reducing wear and tear on the pump. If the endoscopist wants to insufflate the patient, he or she covers the vent hole with a fingertip; this closes off the vent and forces air down the air channel, exiting the instrument through the nozzle on the distal tip. A one-way valve is incorporated into the shaft of the air/water valve to hold air in the patient during an examination. During endoscopy, the GI tract is typically insufflated to a pressure slightly above atmospheric pressure. If it were not for this one-way valve in the system, air from the organ under examination would flow back into the nozzle on the distal tip, up the air channel in the insertion tube, and out the hole in the air/water valve whenever the operator removed his or her finger from the valve. The antireflux valve is required to keep the patient insufflated.