Transcutaneous oxygen and local perfusion measurement

Apparatus for measuring and monitoring blood gas content comprising

• a transcutaneous gas measurement probe including first and second electrodes, said first electrode being formed of a thermally conductive material and having a mass substantially greater than the mass of said second electrode,
• a diaphragm permeable to the gas to be measured and enclosing a region between said first and second electrodes and adapted to confine an electrolytic solution therein,
• means for applying a voltage across said first and second electrodes,
• a semi-conductor device thermally conductively coupled to said first electrode,
• a temperature sensor element thermally conductively coupled to said first electrode, said temperature sensor element having an output voltage with a magnitude proportional to the temperature of said first electrode,
• means for selectively applying an electric current to said semi-conductor device, said selective applying means being responsive to said temperature sensor output voltage for applying said current only when said temperature sensor output voltage is below a predetermined level,
• means for providing a first voltage proportional to the voltage across said semi-conductor device,
• means for producing a second voltage having a magnitude proportional to the current flowing through said semi-conductor device,
• means for producing a product voltage having a magnitude equal to the product of said first and second voltage magnitudes, and
• means for displaying a magnitude dependent on said poduct voltage magnitude.

A method for measuring local perfusion factor in a living body comprising

• applying a probe heated by an electrically energized semi-conductor device to the skin surface of the body,
• obtaining an electrical signal having a magnitude indicative of the temperature of said probe,
• applying an electric current to the semi-conductor device in response to said temperature indicative signal for maintaining the probe at a predetermined constant temperature,
• measuring the power applied to said probe for maintaining said constant temperature by multiplying the magnitude of the current applied to heat said semi-conductor device by the magnitude of the voltage developed across said semi-conductor device.