A cryogenic medical system comprising: at least one cryoengine comprising: a dewar which when filled with liquid nitrogen creates a cryogen reservoir; a pressurization system having a first vessel and a second vessel interconnected by a line and having a valve control, the first vessel has a port and is positioned inside the dewar and the second vessel is positioned outside the dewar, wherein the dewar and the pressurization system are configured such that when the dewar is filled with the liquid nitrogen to create the reservoir, the first vessel is positioned inside the cryogen reservoir and is at or near liquid nitrogen temperature and the second vessel is positioned outside the cryogen reservoir and is at an ambient temperature with the surrounding air or is elevated to an above ambient temperature; a thermocouple sensor protruding through the first vessel; a cryogenic flow actuator that is within the dewar and that is connected to a fill valve which is connected to the port of the first vessel of the pressurization system, wherein the cryogenic flow actuator, the fill valve and the port of the first vessel are configured so that when the dewar is filled with liquid nitrogen to create the cryogenic reservoir, the cryogenic flow actuator can be activated by engagement of a fill motor to start flow of liquid nitrogen from the cryogen reservoir through the fill valve and port and into the first vessel; and one or more cryolines, which are immersed in the cryogen reservoir created when the dewar is filled with liquid nitrogen and which creates a continuous fluid path from the first vessel to connection sites for externally positioned cryoprobes, wherein the pressurization system is configured to generate supercritical cryogen, such that after the dewar is filled with liquid nitrogen to create a cryogenic reservoir, the cryogenic flow actuator is activated by engagement of a fill motor to start flow of liquid nitrogen from the cryogen reservoir through the fill valve and port and into the first vessel, the level of liquid nitrogen within the first vessel is measured by the thermocouple sensor and following filling of the first vessel, the valve control is opened to create a continuous pressurization system comprising a volume of liquid nitrogen in the first vessel and an equal volume of nitrogen vapor in the second vessel, and a heater internal to the first vessel is activated, a boiling microenvironment in the liquid nitrogen is created to produce nitrogen gas and increase pressure in the pressurization system through the beyond the critical point of nitrogen to create supercritical nitrogen. a dewar which when filled with liquid nitrogen creates a cryogen reservoir; a pressurization system having a first vessel and a second vessel interconnected by a line and having a valve control, the first vessel has a port and is positioned inside the dewar and the second vessel is positioned outside the dewar, wherein the dewar and the pressurization system are configured such that when the dewar is filled with the liquid nitrogen to create the reservoir, the first vessel is positioned inside the cryogen reservoir and is at or near liquid nitrogen temperature and the second vessel is positioned outside the cryogen reservoir and is at an ambient temperature with the surrounding air or is elevated to an above ambient temperature; a thermocouple sensor protruding through the first vessel; a cryogenic flow actuator that is within the dewar and that is connected to a fill valve which is connected to the port of the first vessel of the pressurization system, wherein the cryogenic flow actuator, the fill valve and the port of the first vessel are configured so that when the dewar is filled with liquid nitrogen to create the cryogenic reservoir, the cryogenic flow actuator can be activated by engagement of a fill motor to start flow of liquid nitrogen from the cryogen reservoir through the fill valve and port and into the first vessel; and one or more cryolines, which are immersed in the cryogen reservoir created when the dewar is filled with liquid nitrogen and which creates a continuous fluid path from the first vessel to connection sites for externally positioned cryoprobes, wherein the pressurization system is configured to generate supercritical cryogen, such that after the dewar is filled with liquid nitrogen to create a cryogenic reservoir, the cryogenic flow actuator is activated by engagement of a fill motor to start flow of liquid nitrogen from the cryogen reservoir through the fill valve and port and into the first vessel, the level of liquid nitrogen within the first vessel is measured by the thermocouple sensor and following filling of the first vessel, the valve control is opened to create a continuous pressurization system comprising a volume of liquid nitrogen in the first vessel and an equal volume of nitrogen vapor in the second vessel, and a heater internal to the first vessel is activated, a boiling microenvironment in the liquid nitrogen is created to produce nitrogen gas and increase pressure in the pressurization system through the beyond the critical point of nitrogen to create supercritical nitrogen.