Adapter cable for connecting a pulsoximetry sensor unit to a medical measuring device

An adapter cable for connecting a pulsoximetry sensor unit to a medical measuring device,

• said pulsoximetry sensor unit comprising two antiparallel-connected, light-emitting elements for emitting light of different wavelengths into a part of the body supplied with pulsating blood and a photosensitive element for receiving light which has been allowed to pass through said part of the body supplied with pulsating blood, and
• said medical measuring device providing a pulsed supply signal, which supplies power to the light-emitting elements, and determining, on the basis of a signal produced by said photosensitive element, the oxygen saturation of the hemoglobin contained in the blood of the transilluminated part of the body,
• wherein said adapter cable comprises the following features:
• first and second lines for connecting the antiparallel-connected, light-emitting elements with supply terminals of the medical measuring device;
• a third line for connecting one terminal of the photosensitive element to a measuring signal input of the medical measuring device;
• a fourth line for connecting another terminal of the photosensitive element to a first node;
• a first resistor connecting the first node to a second node;
• a fifth line for connecting the second node to a reference potential terminal of the medical measuring device;
• an electronic switch means, which is connected at least to one of said first or second lines in such a way that, when said electronic switch means is activated, a flow of limit-exceeding current through the light-emitting elements will be prevented, and
• a fault current detection circuit, having an input side connected to said first and second nodes and having an output side connected to said electronic switch means and responsive to a voltage drop across the first resistor exceeding a limit value so as to activate said electronic switch means.

An adapter cable for connecting a pulsoximetry sensor unit to a medical measuring device,

• said pulsoximetry sensor unit comprising two antiparallel-connected, light-emitting elements for emitting light of different wavelengths into a part of the body supplied with pulsating blood, a photosensitive element for receiving light which has been allowed to pass through said part of the body supplied with pulsating blood, and a coding resistor whose resistance value is representative of the wavelength of the light emitted by one of said light-emitting elements, and
• said medical measuring device providing a pulsed supply signal, which supplies power to the light-emitting elements, and determining, on the basis of a signal produced by said photosensitive element, the oxygen saturation of the hemoglobin contained in the blood of the transilluminated part of the body,
• wherein said adapter cable comprises the following features:
• first and second lines for connecting the antiparallel-connected, light-emitting elements with supply terminals of the medical measuring device;
• a third line for connecting one terminal of the photosensitive element to a measuring signal input of the medical measuring device;
• a first grounding line for connecting another terminal of the photosensitive element to a first node;
• a coding resistor connection line for connecting one terminal of the coding resistor to a coding resistor terminal of the measuring device;
• a second grounding line for connecting another terminal of the coding resistor to the first node;
• a third grounding line constructed as an outer shield of the adapter cable and connected to the first node;
• a first resistor connecting said first node to a second node;
• a fifth line for connecting the second node to a reference potential terminal of the measuring device;
• an electronic switch means connected to said first and second lines and forming, when activated, a shunt for at least one of the light-emitting elements;
• and
• a fault current detection circuit, which responds to a voltage drop across the first resistor exceeding a limit voltage, so as to activate said electronic switch means.