# US 9,516,875 B2 · Systems and methods for ex vivo lung care > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,516,875 B2 - Document ID: US9516875B2 - Status: Granted - Kind: B2 - Application number: 13/765,009 - Filed: 2013-02-12 - Published: 2013-06-20 - Granted: 2016-12-13 - Earliest claimed: 2008-01-31 - Assignees: Transmedics, Inc. - Applicants: TransMedics, Inc - Inventors: Robert Fishman; Robert Havener; Ihab A. Fattah; Anas Abdelazim; Scott Newell; Thomas H. Bishop; Tamer I. Khayal; Stanley Kyi; Ron Taylor, Jr.; Doug Harriott; Matthew De Remer; Paul Murray; John Sullivan; Mark Anderson; Richard Bringham; Michael Van Driel; Waleed H. Hassanein - Web page: https://patentgrep.com/patent/US9516875B2 ## CPC - A01N 1/122: Preservation or perfusion media - A01N 1/10: Preservation of living parts - A01N 1/143: for organ perfusion - A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS ## Abstract Methods and systems of maintaining, evaluating, and providing therapy to a lung ex vivo. The methods and systems involve positioning the lung in an ex vivo perfusion circuit; circulating a perfusion fluid through the lung, the fluid entering the lung through a pulmonary artery interface and leaving the lung through a left atrial interface; and ventilating the lung by flowing a ventilation gas through a tracheal interface. Maintaining the lung for extended periods involves causing the lung to rebreath a captive volume of air, and reaching an equilibrium state between the perfusion fluid and the ventilation gas. Evaluating the gas exchange capability of the lung involves deoxygenating the perfusion fluid and measuring a time taken to reoxygenate the perfusion fluid by ventilating the lung with an oxygenation gas. ## Claims ### Claim 1 A method of preserving a lung ex vivo comprising: circulating a perfusion fluid through the lung, the fluid entering the lung through a pulmonary artery interface and leaving the lung through a left atrial interface; ventilating the lung through a tracheal interface by flowing a captive volume of a ventilation gas back and forth between the lung and a variable volume chamber; and introducing into the captive volume an additional flow of the ventilation gas wherein the additional flow is about 10% of a tidal volume and venting excess ventilation gas from the captive volume using a pneumatic control system that controls at least a valve to maintain a predetermined composition of the ventilation gas and to maintain a minimum gas pressure of the captive volume. ### Claim 2 (depends on 1) The method of claim 1, wherein the ventilation gas includes a composition of oxygen, carbon dioxide and an inert gas. ### Claim 3 (depends on 2) The method of claim 2, wherein the inert gas is nitrogen. ### Claim 4 (depends on 1) The method of claim 1, wherein a gas content of the perfusion fluid reaches an equilibrium level corresponding to the predetermined composition of the ventilation gas. ### Claim 5 (depends on 1) The method of claim 1, wherein the predetermined composition of the ventilation gas includes about 5-20% oxygen and about 2-10% carbon dioxide. ### Claim 6 (depends on 5) The method of claim 5, wherein a gas content of the perfusion fluid reaches an equilibrium level, the equilibrium level having a hemoglobin saturation level of about 88%-98%. ### Claim 7 (depends on 1) The method of claim 1, wherein the predetermined composition of the ventilation gas includes about 12% oxygen and about 5.5% carbon dioxide. ### Claim 8 (depends on 7) The method of claim 7, wherein a hemoglobin saturation level of the perfusion fluid entering the lung reaches an equilibrium level of about 90-95% and a hemoglobin saturation level of the perfusion fluid leaving the lung reaches an equilibrium level of about 90-95%. ### Claim 9 (depends on 1) The method of claim 1, wherein an oxygen content of the perfusion fluid entering the lung is lower than physiologic levels, and an oxygen content of perfusion fluid leaving the lung is higher than physiologic levels. ### Claim 10 (depends on 1) The method of claim 1, wherein the additional flow of ventilation gas is about 400-600 mL per minute. ### Claim 11 (depends on 1) The method of claim 1, wherein the captive volume is about 400-1200 mL. ### Claim 12 (depends on 1) The method of claim 1, wherein the minimum gas pressure of the captive volume is about 4-8 cm of H2O. ### Claim 13 (depends on 1) The method of claim 1, wherein a maximum pressure of the ventilation gas is about 12-22 cm of H2O. ### Claim 14 (depends on 1) The method of claim 1, wherein the excess ventilation gas is vented through a relief valve in communication with the captive volume. ### Claim 15 (depends on 1) The method of claim 1, wherein the variable volume chamber comprises a bellows. ### Claim 16 (depends on 15) The method of claim 15, further comprising compressing the bellows to cause the flow of ventilation gas into the lung. ### Claim 17 (depends on 16) The method of claim 16, wherein a volume of ventilation gas that is flowed between the bellows and the lung is determined by a magnitude of a compression stroke of the bellows. ### Claim 18 (depends on 1) The method of claim 1, wherein the flow of ventilation gas out of the lung is caused by contraction of the lung. ### Claim 19 (depends on 1) The method of claim 1, wherein the pulmonary artery interface includes a pulmonary artery cannula, a portion of the pulmonary artery cannula being inserted into a pulmonary artery of the lung. ### Claim 20 (depends on 1) The method of claim 1, wherein the perfusion fluid flows away from the lung through an exposed left atrial cuff. ### Claim 21 (depends on 1) The method of claim 1, wherein the left atrial interface includes a sealed connection between a left atrium of the lung and a left atrial cannula. ### Claim 22 (depends on 1) The method of claim 1, wherein the tracheal interface includes a tracheal cannula, a portion of the tracheal cannula being inserted into a trachea of the lung. ### Claim 23 (depends on 1) The method of claim 1, wherein the perfusion fluid is maintained at a near physiologic temperature. ### Claim 24 (depends on 1) The method of claim 1 further comprising measuring a first level of oxygen content in the perfusion fluid flowing into the lung and a second level of oxygen content in the perfusion fluid flowing out of the lung. ### Claim 25 (depends on 1) The method of claim 1 further comprising measuring at least one of a level of oxygen saturation of hemoglobin in the perfusion fluid and a partial pressure of oxygen in the perfusion fluid flowing into the lung. ### Claim 26 (depends on 1) The method of claim 1 further comprising measuring at least one of a level of oxygen saturation of hemoglobin in the perfusion fluid and a partial pressure of oxygen in the perfusion fluid flowing out of the lung. ### Claim 27 (depends on 1) The method of claim 1, wherein the perfusion fluid comprises a blood product. ### Claim 28 (depends on 27) The method of claim 27, wherein the perfusion fluid is at least partially depleted of leukocytes. ### Claim 29 (depends on 28) The method of claim 28, wherein the perfusion fluid is at least partially depleted of platelets. ### Claim 30 (depends on 1) The method of claim 1, wherein the perfusion fluid comprises whole blood. ### Claim 31 (depends on 1) The method of claim 1, further comprising delivering one or more therapeutics to the lung during perfusion. ### Claim 32 (depends on 31) The method of claim 31, wherein the one or more therapeutics are selected from antimicrobials, vasodilators, and anti-inflammatory drugs. ### Claim 33 (depends on 31) The method of claim 31, wherein the one or more therapeutics are selected from the group consisting of prostaglandins, prostacyline, dextran, isuprel, flolan, and nitric oxide donors. ### Claim 34 (depends on 31) The method of claim 31, wherein the one or more therapeutics are delivered through the tracheal interface through one of a nebulizer and a bronchoscope. ### Claim 35 (depends on 1) The method of claim 1, further comprising establishing a desired level of oxygen content in the perfusion fluid prior to initiating perfusion of the lung. ### Claim 36 (depends on 35) The method of claim 35, wherein the desired level of oxygen content in the perfusion fluid corresponds to a hemoglobin saturation level of about 88%-98%. ### Claim 37 A method of preserving a lung ex vivo comprising: circulating a perfusion fluid through the lung, the fluid entering the lung through a pulmonary artery interface and leaving the lung through a left atrial interface; ventilating the lung through a tracheal interface by flowing a captive volume of a ventilation gas back and forth between the lung and a variable volume chamber; introducing into the captive volume an additional volume of the ventilation gas wherein the additional volume of the ventilation gas is about 10% of a tidal volume and venting excess ventilation gas from the captive volume using a pneumatic control system that controls at least a valve to maintain a predetermined composition of the ventilation gas and to maintain a minimum gas pressure of the captive volume; and wherein a gas exchange in the lung between a component of the ventilation gas and the perfusion fluid causes the corresponding gas component in the perfusion fluid to reach an equilibrium value. ### Claim 38 (depends on 37) The method of claim 37, wherein the component of the ventilation gas is at least one of oxygen and carbon dioxide.