Anesthetic circuit having a hollow fiber membrane

A fluid separation apparatus fluidly connectable to an anesthetic circuit, the anesthetic circuit having a flow passage for transporting an exhaled fluid mixture containing at least exhaled anesthetic agent and exhaled carbon dioxide through the flow passage, the fluid separation apparatus comprises:

• a membrane having a plurality of hollow fibers, wherein
• the membrane is at least partially impervious to the exhaled anesthetic agent to at least partially retain the exhaled anesthetic agent in the flow passage after the exhaled fluid mixture contacts the membrane, and
• the membrane is more pervious to the exhaled carbon dioxide than the exhaled anesthetic agent such that the membrane has an exhaled carbon dioxide-to-exhaled anesthetic agent selectivity of greater than 1;
• and
• a membrane housing containing the membrane therein, wherein
• the housing is configured to receive the exhaled fluid mixture via a housing inlet,
• the membrane housing directs the exhaled fluid mixture into contact with the membrane, to provide a modified fluid mixture having a lower amount of the exhaled carbon dioxide than the exhaled fluid mixture,
• the membrane housing directs the modified fluid mixture out of the membrane housing via a housing outlet,
• the at least one hollow fiber permits a sweep fluid to pass therethough to facilitate the transport of at least a portion of the exhaled carbon dioxide into the at least one hollow fiber, and
• the membrane housing has at least one sweep inlet to receive the sweep fluid therethrough and at least one sweep outlet to expel the sweep fluid from the membrane housing.

A method for anesthetic treatment of a patient, comprising:

• introducing an external anesthetic agent towards and into the patient via a flow passage;
• directing an exhaled fluid mixture comprising an exhaled oxygen, an exhaled carbon dioxide and an exhaled anesthetic agent away from and out of the patient into the flow passage;
• advancing the exhaled fluid mixture through the flow passage towards and into contact with a membrane comprising a plurality of hollow fibers in fluid communication with the flow passage;
• transferring more of the exhaled carbon dioxide than the exhaled anesthetic agent from the exhaled fluid mixture through the membrane and out of the flow passage after the exhaled fluid mixture contacts the membrane to leave a modified fluid mixture in the flow passage, wherein the modified fluid mixture has a lower concentration of the exhaled carbon dioxide than the exhaled fluid mixture;
• and
• advancing the modified fluid mixture through the flow passage toward the patient to provide at least the modified fluid mixture to the patient.