Thermal management of bio-implant and implantable medical devices (IMDs) has gained growing attention to prevent overheating in the surrounding tissue of IMDs in certain applications, such as neural prostheses like deep brain stimulators (DBS). This paper focuses on implementation of nonlinear model predictive control (NMPC) methods for adaptive thermal management of IMDs with multiple heat sources. Thermal dynamics of the IMD is modelled using an identification algorithm introduced in previous papers. Interior point optimization method is implemented with the NMPC to solve for the nonlinear optimization problem for adaptive thermal management of IMDs with multiple heat sources. The NMPC implementation is validated using the COMSOL software simulations.