Abstract: A device for use in constructing a breathing circuit has at least a first tube and a filter; the filter has a proximal and a distal end; the first tube is attached to the filter distal end. A second tube can be attached to the filter proximal end, wherein the second tube can be detached from the filter for reuse in a breathing circuit formed with the foregoing components. The filter and the first tube may be disposed of after a single use. The first tube has a length sufficient to maintain the filter at a desired distance from a patient airway device when connected thereto. In a preferred embodiment, a fresh gas outlet is provided at the distal end of the first tube resulting in minimal or substantially no mixing space in the circuit, while the disposable first tube and filter create less medical waste than that created by prior art circuits. Mixing space refers to space distal of the fresh gas outlet into the circuit where the fresh gases can mix with recirculated or other gases.

Abstract: A breathing circuit comprising first and second conduits, wherein at least one of the conduits is a non-conventional conduit. In an embodiment, a multilumen unilimb breathing circuit has first and second conduits, wherein when the proximal ends of said first and second conduits are each connected to an inlet and outlet fitting, respectively, axial extension or contraction of the second conduit causes a corresponding axial extension or contraction of the first conduit. In an embodiment, at least one of said conduits is coiled. In another embodiment, a coiled conduit is contained within an outer flexible conduit that is axially extendable and compressible, forming a unilimb, multilumen respiratory circuit. The outer flexible conduit may be pleated to provide for non-rebounding axial extension and contraction. The multilumen respiratory circuit can provide a variable rebreathing volume.

Abstract: A multilumen unilimb breathing circuit with a detachable proximal fitting for providing respiratory gases to and receiving expiratory gases from a patient. The circuit has unique fittings for connection to patient devices or assisted ventilation systems and components. Despite many teachings away in the prior art from making breathing circuit tubing detachable from the proximal terminal, the proximal end of the rigid multilumen proximal fitting can be attached and detached by a user at a site of use to a mating multilumen proximal terminal while its distal end can be attached to multiple lumens formed of flexible tubing for carrying gases to and from a patient. The present invention introduces for the first time to the multilumen unilimb circuit art a detachable proximal fitting.