GB1370943A - Tatient monitoring systems - Google Patents

Abstract

1370943 Electro-medical apparatus NATIONAL RESEARCH DEVELOPMENT CORP 15 March 1972 [18 March 1971] 7202/71 Heading GIN In a patient monitoring system utilizing the trend of parameter valves representing a patients condition at least two integrating means are provided to produce respective time-loaded integrated signals in response to transducer signals representing respectively different patient parameters, and these signals are compared with respective reference level signals to produce respective digital signals indicating whether the integrated signals are above or below the associated reference level signals, at least one predetermined combination of digital signals operating a warning or alarm indicator via logic circuitry. As shown, four transducers 1a-1d provide signals representing mean arterial blood pressure, pulse rate, mean central venous blood pressure, and temperature (body core temperature, skin temperature or the difference between these), these signals being applied to respective integrator/comparators 2a-2d, and to comparators 3a-3d. The digital output signals of all comparators are applied to logic circuitry 4 which operates a warning or alarm indicator 5, 6. The outputs of comparators 3a-3d are also applied to logic circuitry 8 which operates a fault indicator 9. When a fault occurs, an output from indicator 9 holds all the integrators. Preferably each comparator contains a high comparator and a low comparator provided with respective high and low reference level signals, Fig. 2 (not shown). Further each integrating means comprises a short-time interval and a long-time interval integrator, the outputs of these two integrators being compared with associated reference level signals and also being applied to difference amplifiers whose output is also compared with associated reference level signals, Fig. 3 (not shown). Each comparator may be provided also with an up-dated reference derived from integrating over a long period the associated transducer signal and comparing the integrated signal with fixed references, Fig. 6 (not shown). As examples, a warning state is denoted by the combination of a trend to a low level over a long term for mean arterial blood pressure with a trend to high level over a long term for pulse rate. An alarm state is denoted by a combination of a trend to a high level, negative long term/short term difference signal for mean arterial blood pressure with a trend to a high long term/short term difference signal, whether positive or negative, for pulse rate.