Abstract: A system for testing the attachment of an electrocardiograph (ECG) electrode intended to be used in connection with an electrode monitoring the function of the heart, muscles or other organs to indicate detachment of the electrode from its fixing base, said electrode being provided with voltage monitoring apparatus. The electrode comprises a capacitive sheath insulated from the electrode and from its fixing base and an alternating voltage source arranged to supply a signal voltage to the sheath so that on detachment of the electrode from its fixing base immediately an alternating voltage is induced from the sheath to the electrode.

Abstract: A method of determining arterial carbon dioxide tension from mixed expired gases of a patient utilizing a partial rebreathing anesthesia circuit. An electrode is inserted into expired gases of a patient to measure expired carbon dioxide tension. An output signal from the electrode, which indicates expired carbon dioxide tension, has a very high impedance. By reducing the impedance of the output signal, a more usable signal is obtained. Also, the signal must be converted to a relatively linear function, which is then scaled to give a visual indication proportionate to the arterial carbon dioxide tension. The electrode is pre-calibrated by gases having known percentages of carbon dioxide. The scaling factor is included to compensate for differences between the expired carbon dioxide tension and arterial carbon dioxide tension.