A probabilistic digital signal processor using data from multiple instruments is described. In one example, a digital signal processor is integrated into a biomedical device. The processor is configured to: use a dynamic state-space model configured with a physiological model of a body system to provide a prior probability distribution function receive sensor data input from at least two data sources and iteratively use a probabilistic updater to integrate the sensor data as a fused data set and generate a posterior probability distribution function using all of: (1) the fused data set (2) an application of Bayesian probability and (3) the prior probability distribution function. The processor further generates an output of a biomedical state using the posterior probability function.