Hewlett-packard Company

Joachim Vester

Heinz Sommer

Michael Blank

Bernhard Wider

An adapter cable is used for connecting a pulsoximetry sensor unit to a medical measuring device. The pulsoximetry sensor unit comprises, among other components, two antiparallel-connected, light-emitting diodes, which are activated alternatingly by a pulse current source of the medical measuring device. Between said pulsoximetry sensor unit and said medical measuring device, a plurality of grounding lines extend within the adapter cable. In the case of a short circuit between one of the two supply lines of the antiparallel-connected, light-emitting elements and one of the grounding lines, the fault current is caused to flow in the grounding lines to a first node in accordance with the present invention, said first node being adapted to be connected to a reference potential of the medical measuring device via a first resistor. The voltage drop across said first resistor will cause firing of a thyristor structure, if a limit value is exceeded, provided that the instantaneous control phase of the pulse current source of the medical measuring device can cause an activation of a predetermined element of the two light-emitting elements. The triggered thyristor circuit will cause an activation of a switch, which will establish a shunt to the light-emitting elements.

Adapter cable for connecting a pulsoximetry sensor unit to a medical

A system for invasive measuring of blood gas parameters, such as pH, pO.sub.2 or pCO.sub.2 , or for measuring other parameters influencing the time constant of the excited state of a fluorescent dye, comprises a light generation device including a generator (2), a delay device (4) and a light source (6), a fluorescent measuring probe (1), a light reception device (16), a light guide device, which is adapted to be switched over and which, in its first switching state, optically connects the light source (6) to the fluorescent measuring probe (1) and said probe (1) to the light reception device (16) and which, in its second switching state, establishes an optical connection between the light source (6) and the light reception device (16), a phase metering device (17to 20, 23 to 27) as well as an evaluation device (28), which, in the second switching state of the light guide device (7), determines the transfer characteristic of the blood gas parameter measuring system and which, in the first switching state of the light guide device (7), determines the measuring value of the blood gas parameter on the basis of the transfer characteristic, the output signal of the phase metering device (17 to 20, 23 to27) and a correlation between the respective values of the blood gas parameter and the associated values of the time constant of the fluorescent measuring probe (1), said correlation being predetermined for the fluorescent measuring probe (1).

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Aidlingen, Germany

Joachim Vester