National Institute for Health and Care Excellence categorisation of track and trigger systems
| Single parameter system | Periodic observation of selected vital signs that are compared with a simple set of criteria with predefined thresholds, with a response algorithm being activated when any criterion is met |
| Multiple parameter system | Response algorithm requires more than one criterion to be met or differs according to the number of criteria met |
| Aggregate scoring system | Weighted scores are assigned to physiological values and compared with predefined trigger thresholds |
| Combination system | Single or multiple parameter systems used in combination with aggregate weighted scoring systems |