Carbon dioxide measurement from expired gases in a partial rebreathing anesthesia circuit
US4269194A · kind A · utility
Inventors
Key dates
| Filing date | May 17, 1979 |
| Grant date | May 26, 1981 |
| Priority date | — |
| Expiry date | May 17, 1999 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61M2230/432
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.