Abstract: A system for providing anesthesia or assisted ventilation that has a post-inspiratory valve fresh gas flow input is disclosed. In a preferred embodiment, a fresh gas flow diverter valve is provided to permit an operator to provide fresh gas flow proximally or distally of the inspiratory valve. Also disclosed is an adaptor and other breathing circuit components for forming a system of the present invention. A method of providing anesthesia or assisted ventilation using low flow fresh gas is disclosed.

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 breathing circuit comprising first and second conduits is disclosed, wherein at least one of the conduits is a non-conventional conduit. A multilumen unilimb breathing circuit is also disclosed having 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, movement of the distal end of the first conduit causes a corresponding movement of the distal end of the second conduit. In an embodiment, inner and outer flexible conduits are formed of pleated tubing that is axially extendable and compressible to form a unilimb multilumen respiratory circuit. The pleating provides for axial extension and contraction. The multilumen respiratory circuit can provide a variable rebreathing volume. In an embodiment, at least one tube in a multilumen respiratory conduit is radially collapsible and radially expandable to a maximum radius for carrying respiratory gases to and from a patient.