In a medical monitoring system ( 10 ), one or more biometric monitors ( 20, 21, 22, 23, 24, 26, 66 ) collect data of a plurality of monitored biometric parameters. An expression evaluator ( 72 ) evaluates a user-defined expression incorporating one or more of the monitored biometric parameters to generate data for a user-defined biometric parameter. A further processing component ( 32, 50, 52, 54, 55, 56, 57, 58, 60, 62, 88 ) performs processing and display of data of at least one parameter selected from the monitored bio-metric parameters and the user-defined biometric parameter. The further processing component operates in the same way regardless of whether the at least one parameter is selected from the monitored biometric parameters or the user-defined biometric parameter.
