Simultaneous on-line measurement of blood K+, Ca2+, Na+, and pH with a four-function ChemFET integrated-circuit sensor.

On-line, simultaneous measurement of blood K+, Ca2+, Na+, and pH has been achieved by using a quadruple-function ChemFET (chemical-sensitive field-effect transistor) integrated-circuit sensor. Blood is withdrawn from the subject through an actively heparinized, dual-lumen cannula and passed into a flow-cell containing the sensor, in alternation with a calibration solution. A minicomputer controls the analysis system, logs data, and provides a continuous, graphic display of K+ and pH values.