Abstract: Systems and methods for gas exchange in a patient are provided that use an external circuit to cause oxygenation perfusion in a patient's body cavity (such as the abdomen) using an inert chemical (e.g., perfluorocarbon), independent of the lungs. The external circuit includes components configured to control properties of the chemical, including temperature, flow rate, pressure, oxygenation percentage, carbon dioxide percentage. The system also includes safety features to reduce the likelihood of injury to the patient. Each of the safety features and chemical properties can be controlled by a healthcare worker, such as a physician, nurse, or emergency operator, for a particular patient.