Working channels for a disposable sheath for an endoscope

Abstract

An endoscopic sheath assembly having an endoscope tube and a plurality of working channels, wherein the endoscope tube is adapted to receive and tightly surround a flexible, elongated endoscope that has a neutral bending plane. Working channels, including a biopsy channel, an air channel, and a water channel, are disposed within and substantially parallel to the endoscope tube along its length radially outward of the neutral bending plane of the endoscope. The biopsy, air, and water channels each have proximal sections and expansion sections. The suction channel has a proximal section comprising a lubricious inner tube forming a lubricious inner lumen, and a kink resistant outer tube bonded to the inner tube. The expansion section of the biopsy channel has a close pitch, axially wound, flat wire spring tightly surrounded by an extruded elastomeric material that is adapted to maintain radial compression force on the spring member. The fiat wire spring forms a durable, lubricious inner lumen of the expansion section of the suction/biopsy channel. The air and water channels have a proximal section formed by a flexible, kink-resistant polyvinyl chloride tube, and an expansion section constructed of a thick-walled elastomeric extrusion that is adapted to axially expand and contract as the channels bend during endoscope articulation. A spirally wound wrap secures the biopsy, air, and water channels together along their distal sections.