An oxygenator includes a housing having a blood inlet and a blood outlet, the blood inlet extending into an interior of the housing. A heat exchanger is disposed within the housing, and is coupled, at an inlet end, to a heat-exchange fluid inlet. A gas exchanger also is disposed within the housing, and includes a bundle of gas-exchange fibers coupled, at a gas outlet end, to a gas-exchange fluid outlet. The oxygenator includes at least one insulator configured to thermally insulate at least the gas outlet end of the bundle of gas-exchange fibers.