Severinghaus pco2 electrode. The electrode is symbolized by two wires in the water bath. 3. It diffuses through a polyethylene membrane. Cutting edge digital technology The digital SenTec V-SignTM Sensor is a Stow-Severinghaus-type PCO2 sensor combined with 2-wavelength reflectance pulse oximetry. It was developed by Dr. The internal solution of the glass electrode is 0. . The accuracy and working Jun 6, 2015 · This is relevant for Question 9. permeable, hydrogen 3. Dec 1, 2004 · Download Citation | First electrodes for blood PO2 and PCO2 determination | This essay looks at the historical significance of an APS classic paper that is freely available online: Severinghaus JW Jul 6, 2011 · We used standard recommendations with the anaerobic factor (Severinghaus constant) turned on, and with a metabolic constant set at 0. The jacket is capped with a Teflon membrane that is permeable to CO2. 4 mV/h, and the lifetime has been extended from hours or days to one month. The accuracy and working Has two chemical half-cells, reference and measuring electrode, connected by a KCL bridge What does the severinghaus electrode measure, describe the components, and explain its priciple opertation Measure PCO2. 1 N HC1[35]. The accuracy and pH Electrode PCO2 Electrode PO2 (Clark) Authored by William A. Results are presented to show that such an analyser will provide extremely accurate and reproducible results over a limited range around the calibration point, and this technique has been applied to the measurement of the apparent blood-gas and water-gas difference for a Pco2 electrode. Sensitivity can be set In 1957, we added our Stow-Severinghaus PCO2 electrode to that thermostat, the first blood gas analysis system (see figures 1 and 2 in Ref. French. In 1960, Severinghaus described the measurement of PCO2 via human skin using a specially designed, temperature-stabilized tissue PCO2 electrode (15). Invented by John _______ in ______ 2. This PCO 2 electrode contains the CO 2 -permeable membrane and the principle of pH meter with a pH-sensitive glass membrane. Career perspective: John W. CO2 diffuses from the blood sample across a CO2-permeable membrane into a bicarbonate solution This causes it to dissociate to form H+ ions The traditionally used electrode for measuring PCO2 is termed the Severinghaus PCO2 electrode, per the last name of the inventor of this electrode, Dr. Jun 18, 2021 · Within days, Severinghaus had begun the design of a water bath containing the PCO2 and PO2 electrodes, with a stirred cuvette for the Clark electrode. Jun 12, 2005 · Both electrodes must be kept at 37°C, clean and calibrated with buffer solutions of known pH. The Severinghaus electrode measures PCO2 potentiometrically by the adaptation of what measurement? Dec 4, 2023 · This is accomplished through an ion-selective electrode, which is sensitive to the presence of certain ions—in this case, carbon dioxide (CO2). Use of end-tidal PCO2 and transcutaneous PCO2 as noninvasive measurement of arterial PCO2 in extubated patients recovering from general anesthesia. Stow used a glass pH electrode, which was covered by a plastic membrane. Used in ABG analysis. voltmeter PCO2 - Severinghaus Electrode: PCO2 - Severinhaus Electrode: 1. 1958. A systematic experimental and theoretical assessment of the Severinghaus Pco2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus. The calomel reference electrode should be maintained at a constant temperature because a A simple, single calibration point, single control Pco2 analyser is described. 17 Arterial Blood Gases Severinghaus Electrode (PCO2) The PCO2 electrode is a modified pH electrode. Severinghaus-Type Electrode Severinghaus developed a technique known as transcutaneous monitoring, allowing for the continuous and non-invasive monitoring of CO 2 levels, modifying the Stow electrode, which was composed of a rubber membrane on a glass electrode with water in between [58, 81]. May 1, 1999 · The Severinghaus-type pCO(2) electrode was miniaturized and batch-fabricated using semiconductor and micromachining techniques. A number of new recommendations are made on the operation of the electrode including the following. reference, pH 2. Two membranes: nylon and silastic. Electrodes were found to exhibit a pronounced memory effect, which depended upon t … May 1, 1975 · A study of the Radiometer "Severinghaus' Pco2 electrode has been made in order to investigate its stability and reproducibility when exposed to a seri… Abstract A systematic experimental and theoretical assessment of the Severinghaus Pco 2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus. The Severinghaus electrode, which in principle is a pH electrode, measures CO 2 tension by allowing the CO 2 gas to undergo a chemical reaction to produce hydrogen ions. The calomel reference electrode should be maintained at a constant temperature because a 5. 515 No abstract available This Stow-Severinghaus CO 2 electrode is now part of all blood gas analyzers. Electrodes for blood Po2 and Pco2 determination. During the APS Fall Meeting in Iowa City, in 1957, Comroe persuaded Stuart Cullen (1909–1979) to come from Iowa to organize an independent anesthesia department. The measure of pCO2 and pO2 provides essential information about the patient’s metabolism, gas exchange, ventilation, A study of the Radiometer "Severinghaus' Pco 2 electrode has been made in order to investigate its stability and reproducibility when exposed to a series of unknown gas samples of various carbon dioxide concentrations. Yet, 1. This technique was further developed by local heating, which allowed the continuous measurement of blood gases by arterialization of the cutaneous tissue (16). Electrodes were found to exhibit a pronounced memory effect, which depended upon the Pco 2 of the last sample to which they had been exposed if the exposure had been for more ELECTRODES FOR PCO2 (SEVERINGHAUS TYPE PCO2 ELECTRODE) • First pCO2 electrode was developed in 1950’s by Stow & Severinghaus • Used a glass pH electrode as an internal element in a potentiometric cell for measurement of pCO2 • Widely used in modern blood gas analyzers • PVC membrane based electrodes are also available Website : www This communication describes an electronic cir-cuit which exploits the accuracy and reproducibility of a Pco3 electrode close to its calibration point, and which produces a simple and reliable blood-gas analysis system for carbon dioxide (CO3). The carbon dioxide dissolved through the polymer membrane. Barbara Erickson, PhD, RN, CCRN. He developed the Stow-Severinghaus CO2 electrode, the stirred and calibrated Clark O2 electrode, the first 3 function blood gas apparatus (pH, Pco2 and Po2) now at the Smithsonian museum. Severinghaus electrode, Chemistry, Science, Chemistry EncyclopediaThe Severinghaus electrode is an electrode that measures carbon dioxide (CO2). CO2 is proportional to ______ Oct 7, 2013 · This Stow-Severinghaus CO 2 electrode is now part of all blood gas analyzers. ELECTRODES FOR MEASUREMENT OF O2 AND CO, TENSIONS changes, no doubt because the Pco2 is increased in the chamber by increased ambient pressure. “Clark’s electrode was the key discovery,” said Severinghaus. The p CO 2 sensor Much later, actually more than half a century later, the discovery of the pH electrode enabled the development of the p CO 2 sensor by American scientists Stow and Severinghaus. Is basically a ______ system that is modified to measure _______ 3. The AIROF showed a super-Nernstian response with a slope of approximately −80 mV/pH at 25 °C. Authors J W SEVERINGHAUS, A F BRADLEY PMID: 13587443 DOI: 10. [1] Dec 28, 2021 · Carbon dioxide (CO2) monitoring in human subjects is of crucial importance in medical practice. The principle behind this method is that carbon dioxide in a sample will equilibrate with a bicarbonate solution within the electrode, leading to a change in pH. When the gas has been flowing at a fast rate and is stopped, the electrode reading falls, first of all due to pressure changes, but this fall is later overtaken by the fall due to leaks and diffusion. Measuring principle and circuit diagram of the PCO2 electrode. , 1-O2 electrode Orion™ Carbon Dioxide Combination Ion Selective Electrode. The reaction which takes place is an old familiar carbonic acid The Severinghaus electrode is an electrode that measures carbon dioxide (CO 2). Study with Quizlet and memorise flashcards containing terms like It is a medical machine that measures pH and blood gas i. Glass pH and silver reference electrodes were used at 44--45 degrees C, with either circulating water and a copper jacket, or with internal electrical heating. The electrical output is a log function of pCO2 (partial pressure) exposed to Aug 21, 2021 · The traditionally used electrode for measuring PCO 2 is termed the Severinghaus PCO 2 electrode, per the last name of the inventor of this electrode, Dr. , electrodes measure changes in electrical current of voltage and equate these changes with chemical measurement. The Severinghaus electrode is an electrode that measures carbon dioxide (CO 2). The highly integrated digital sensor head comprises a micro pH-electrode and an optical oximetry unit. ? This electrode is essentially a pH electrode exposed to a electrolyte solution that is in equilibrium with the sample through a carbon dioxide-permeable membrane. Upon diffusing through the membrane the carbon dioxide forms carbonic acid through an equilibrium with water, the subsequent dissociation of carbonic acid forms a pH change, which could be measured Apr 14, 2006 · The CO2 electrode is a membrane covered glass pH electrode with an internal electrolyte film containing NaCl and NaHCO3. The gas‐permeable membrane is an essential part of the Severinghaus‐type carbon dioxide electrode. Therefore, the microelectrodes can be extended to low pCO2 measurements. John W. 1 from the second paper of 2008, where the college asked about the mechanics of measuring pH, pO2 and pCO2. Disadvantages: lag time 1-2 minutes Oct 1, 2019 · There is currently no inline potentiometric Severinghaus electrode available for very high DCO 2 concentrations expected in carbonation applications. ysis ofblood content CO2 by measuring a 254o-1 dilu-Their nterest wasprimarily in recording tissue Pco2. R~ is the high-ohmic resistance connected in series to R~, the electrode A systematic experimental and theoretical assessment of the Severinghaus Pco2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus. In fact, it works in exactly the same way, it just has to figure out how to convert CO2 into something involving ions that can then cause a voltage change. Nov 13, 2013 · In 1958, the medical world welcomed the first functioning blood gas analyzer, a large, stationary, three-channel instrument that incorporated a Clark pO2 electrode, the Stow-Severinghaus pCO2 electrode, and a pH electrode. Aug 6, 2015 · Leland C. The CO2 electrode concept had occurred to Gesell in 1925, but for measurement of gas only, and to Gertz and Loeschcke, who were unaware of the Stow-Severinghaus electrode, in 1958. Anodically grown iridium oxide film (AIROF) was employed as the pH sensing element to detect a local pH change caused by the infusion of CO2. 00021. Severinghaus would later incorporate the pH and Pco2 electrodes, along with an oxygen fuel cell, into one machine, resulting in the first blood gas analyser, which became available in 1959. In 1957, I combined it with Leland Clark's polarographic O 2 electrode in a thermostat bath making the first blood gas analyzer (pH, partial pressure of CO 2 (PCO 2), and partial pressure of O 2 (PO 2)) [4] (Figure 1), now in the Smithsonian museum. Theory Henry's law - the amount of gas diffusing across a permeable membrane is directly proportional to the pressure gradient of the gas a reaction occurs as CO2 diffuses into an aqueous bicarbonate solution H+ ions are formed and change the pH the change of CO2 alters pH and therefore a potential is produced Apr 14, 2006 · The CO2 electrode is a membrane covered glass pH electrode with an internal electrolyte film containing NaCl and NaHCO3. For convenience, there may or may not be a bicarbonate solution added to this chamber. 1 mol/1 of HCl. “Fifty years later, every blood gas analyzer contains a Clark type electrode. The electrical output is a log function of pCO2 (partial pressure) exposed to A systematic experimental and theoretical assessment of the Severinghaus Pco2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus, and new recommendations are made on the operation of the electrode. When CO2 diffuses into the cell, it reacts with water, producing carbonic acid, and the pH electrode detects the acidity change What are the advantages and disadvantages or the severinghaus PCO2 electrode? Advantages: can selectively measure CO2 partial pressure in liquid or gas phase. Each sensor’s A simple, single calibration point, single control Pco2 analyser is described. He constructed a glass pH electrode wrapped in a thin, CO 2 -permeable rubber membrane. It may also measure electrolytes ( K, Na, Ca, and Cl) and metabolites as (glucose, lactate, and bilirubin). Results are presented to show that such an analyser will provide extrem… A study of the Radiometer "Severinghaus" Pco2 electrode has been made in order to investigate its stability and reproducibility when exposed to a series of inknown gas samples of various carbon dioxide concentrations. PCO2 is a function of change in pH of bicarb solution (pH changes by 0. This stability are outweighed by the rapid use of the becomes significant with Teflon, where 1% of the oxygen in the sample and by the greater potential November 1958 ELECTRODES FOR BLOOD ~02 AND pCO2 DETERMINATION 517 TABLE I. The Severinghaus electrode consists of: A chamber for the blood sample, separated from the bicarbonate chamber by a CO 2 permeable A systematic experimental and theoretical assessment of the Severinghaus Pco2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus. The paper he published discusses the "continuous recording of blood oxygen tensions by polarography"- it was a "polarographic" electrode, and this is also how it is referred to in some of the earlier literature. EFFECT OF vIscosITY ON PO2 ELECTRODE (R3) having IOOO divisions. The solution internal to the glass membrane is 0. 1MKCl in pure water, and the glass membrane is permeable to H+ only. Yet, such monitors are not only expensive, but also bulky and continuously drifting, requiring frequent recalibrations by trained medical staff FIG. The PCO2 electrode typically employs a gas-permeable membrane that allows CO2 to diffuse into a liquid electrolyte. The sensor, usually a Severinghaus electrode, will calculate the PCO2 electrochemically, usually by a change in pH of an electrolyte solution. ABG analyzer. Here discuss and explain the workings of the Severinghaus pCO2 electrode. Transcutaneous monitors based on the Stow-Severinghaus electrode make a good alternative to the painful and risky arterial “blood gases” sampling. In addition, the microelectrodes can be A Severinghaus electrode, shown below, is used to measure partial pressure of carbon diox- ide PCO2 in a blood sample at room temperature. Ag/AgCl sensing electrode surrounded by KCl buffer encased in pH sensitive glass H+ in blood able to pass through H+ sensitive glass bulb, equilibrates with one side in KCl but not the other due to the presence of buffer which creates a potential difference proportional to the H concentration No battery, measures VOLTAGE Severinghaus CO2 electrode First electrodes for blood PO2 and PCO2 determinationJ Appl Physiol (1985). 13. 1 unit for every 10 mm Hg increase in PCO2 PCO2 (Severinghaus) Electrode: Platinum cathode and Ag/AgCl reference anode immersed in phosphate/KCl buffer. ; (pCO2) and (pO2), in whole blood. The calomel reference electrode should be maintained at a constant temperature because a In 1956, anesthesiologist John W. Apr 14, 2006 · The CO2 electrode is a membrane covered glass pH electrode with an internal electrolyte film containing NaCl and NaHCO3. Stow (1916–) created the first electrode for measuring P co2 in 1957. John Severinghaus (Figure 4) [28, 29]. Jun 8, 2021 · Within days, Severinghaus had begun the design of a water bath containing the PCO2 and PO2 electrodes, with a stirred cuvette for the Clark electrode. It reacts with potassium chloride. 33 times PaCO2 plus 3 mmHg when measured with electrodes calibrated in gas at 44 Carbon dioxide (CO2) monitoring in human subjects is of crucial importance in medical practice. In 1957, we added our Stow-Severinghaus PCO2 electrode to that thermostat, the first blood gas analysis system (see figures 1 and 2 in Ref. J Appl Phys II. Additionally, a temperature correction is used to address the epithelial CO2 produced by heating the skin. The Severinghaus electrode is an electrochemical sensor that measures the partial pressure of carbon dioxide as a voltage Jan 11, 2024 · The Severinghaus electrode is a modified pH electrode. The traditionally used electrode for measuring PCO 2 is termed the Severinghaus PCO 2 electrode, per the last name of the inventor of this electrode, Dr. 1152/jappl. A glucose electrode for fermentation control. Freeman Bradley in 1958. e. Severinghaus and his technician A. Feb 4, 2022 · Learn how the Clark oxygen electrode works, its use as a gas-measuring device and biosensors, and adaptations for medical and industrial applications. 3. Study with Quizlet and memorize flashcards containing terms like -pH Electrode -PCO2 Electrode -PO2 Electrode, -Measuring electrode -Reference electrode, Measuring half cell and more. Electrochemical Sensors 5. 2. The system can be adapted (at the expense of simpli-city) by the addition of extra electronic circuits and another control, so that it is comparable to The Severinghaus electrode measures the partial pressure of CO2 (pCO2) in the patient’s blood sample, which if lower than an acceptable range, is indicative of hyperventilation, a symptom of asthma. The Severinghaus CO 2 sensor remains accurate at 0-30% DCO 2 but loses accuracy when concentration is higher. Feb 1, 2009 · Respiratory gas analysis has now become a standard monitoring technique in anaesthesia: in theatres, intensive care unit, and for the transfer of ventilate We would like to show you a description here but the site won’t allow us. Measure carbon dioxide, carbonate and bicarbonate in aqueous solutions quickly and accurately with this carbon dioxide combination electrode. Analysis of higher harmonic contamination with a modified approach using a grating analyser. 5 kPa. Freeman Bradley Authors Info & Affiliations Publication: Journal of Applied Physiology Volume 13, Issue 3 Mar 27, 1999 · The Severinghaus-type pCO2 electrode was miniaturized and batch-fabricated using semiconductor and micromachining techniques. The electrode has a sealed-in buffer; an Ag-AgCl reference band is the other half-cell. The calomel reference electrode should be maintained at a constant temperature because a Feb 13, 2022 · Electrodes must be kept clean from protein and not damaged Carbon Dioxide Tension Carbon dioxide tension is measured with a Severinghaus electrode, which is based on the pH electrode, as PaCO2 is related to [H +]. Medically reviewed by Dr. The hydrogen ions produced from the chemical reaction cause a difference in Nov 3, 2020 · PCO2 measurement modified glass electrode comprises of a glass pH electrode that is permeable to CO 2 CO2 diffuses from the specimen into the HCO 3 solution where it dissociates with a change in pH which is measured by the electrode potential difference is proportional to CO 2 concentration PO2 measurement Clark electrode or polargraphic electrode The sensor characteristics of the Severinghaus electrode are substantially influenced by the hydrogen carbonate concentration of the internal electrolyte. A systematic experimental and theoretical assessment of the Severinghaus Pco2 electrode has been made with gas, water and He was chief of anesthesia research at NIH from 1953-1958 studying hypothermia use for cardiac and brain surgery. txt - Quiz for ABG analyzermeasures carbon dioxide tensions by allowing the CO2 gas to undergo a chemical reaction that produces hydrogen ions. from publication: The measurement of dissolved and gaseous carbon dioxide The Severinghaus electrode measures pCO2 by utilizing an internal pH sensor. Severinghaus. D. 1152/classicessays. Oct 7, 2013 · This Stow-Severinghaus CO 2 electrode is now part of all blood gas analyzers. May 1, 1975 · A simple, single calibration point, single control Pco2 analyser is described. Nov 1, 2004 · This essay looks at the historical significance of an APS classic paper that is freely available online: Severinghaus JW and Bradley AF. ” The principle was TheCO2 electrode can be used for electrometric anal- the same as that ofthe Stow-Severinghaus electrode. The CO2 dissolved in the sample diffuses into the middle compartment of the electrode via a thin membrane. Oct 23, 2024 · The Severinghaus electrode is used in blood gas machines to measure CO 2 tension and is a modification of the pH electrode. The electrodes used follow the same principles as outlined, but an additional component allows CO 2 from the blood to drive a pH change that is in turn detected by the electrode. Electrodes for Blood pO2 and pCO2 Determination Authors: John W. The candidates were expected to submerge deeply into the physics and chemistry of ion-selective electrodes. (born 1922) combined newly invented electrodes that measured the partial pressure of carbon dioxide (PCO2) and the partial pressure of oxygen (PO2) in samples of blood in a single apparatus. It reacts with water to form carbonic acid. The detection limit has been lowered to 200 μatm, and the t98 for low pCO2 response is 2 min. 2: First three-function blood gas apparatus (pH, partial pressure of carbon dioxide [pCO2], and partial pressure of oxygen [pO2] electrodes) built by Severinghaus and Bradley (1959). 2004. The calomel reference electrode should be maintained at a constant temperature Abstract A simple, single calibration point, single control Pco2 analyser is described. Clark never called his device "the Clark Oxygen Electrode", as such a gesture would probably have been viewed by his contemporaries as mildly disgusting. The skin surface PCO2 at 44 degrees C is about 1. All data is digitized in the sensor head, allowing the transmission of robust, low-noise signals to the monitor. Severinghaus and A. Study with Quizlet and memorize flashcards containing terms like name the Blood Gas Analyzers and their electrode type, Sanz Electrode, also called Measures Type of device, what theyre made of, how they measure, calibration, PCO2 Electrode, other name Calibration Sits in what kind of bath Covered with and more. Consider the Severinghaus electrode shown below for measurement of pCO2. The polarogram is Measures: PCO2 Components and principle of operation: H+ between inside and outside reference, includes Sanz electrode, double electrode, inner reference, outer measuring surface, and two membranes, a nylon mesh and silastic hydrolysis occurs bicarb I dentify what the Clark electrode measures, describe components, and explain principle of operation Dec 15, 1997 · The classic Severinghaus pCO2 microelectrodes have been greatly improved. In a partial pressure of oxygen (PCO2) electrode, carbon dioxide does which of the following? 1. tion f blood with 0. Anodically grown iridium oxide film (AIROF) was employed as the pH sensing element to detect a local pH change caused by the infusion of CO(2). Download scientific diagram | Main components and mode of operation of the Severinghaus carbon dioxide sensor. The drift is reduced from ∼10 to 0. Severinghaus developed Stow's electrode, stabilizing it with a bicarbonate-salt solution and a spacer. The entire electrode is encased in Lucite jacket filled with bicarbonate electrolyte. Electrodes were found to exhibit a pronounced memory effect, which depended upon the Pco 2 of the last sample to which they had been exposed if the exposure had been for more In 1957, we added our Stow-Severinghaus PCO2 electrode to that thermostat, the first blood gas analysis system (see figures 1 and 2 in Ref. Astrup and origin of base excess Abstract Transcutaneous PCO2 electrodes habe been constructed and evaluated on adults and children. The AIROF showed a super-Ner … A study of the Radiometer "Severinghaus' Pco 2 electrode has been made in order to investigate its stability and reproducibility when exposed to a series of unknown gas samples of various carbon dioxide concentrations. doi: 10. Two years later, several companies began to manufacture these medical monitoring devices, and by 1966, blood gas analysis was widely used in clinical settings, surgery Apr 2, 2010 · The Sanz electrode with pH sensitive glass measures the change in hydrogen concentration across the pH sensitive glass membrane. Modified sanz electrode, double electrode, inner reference and out measuring. Severinghaus, M. A novel thin-film Ag/AgCl Apr 18, 2022 · The Severinghaus Electrode is used to measure the carbon dioxide (CO2, pCO2), and has been employed to measure pCO2 in blood gas analysers. John Severinghaus ( Figure 4) [28,29]. Figure 1. Aug 6, 2015 · The Severinghaus electrode is essentially a slightly modified glass electrode. The electrical output is a log function of pCO2 (partial pressure) exposed to Mar 7, 2018 · Severinghaus Electrode Richard W. PCO2 (Severinghaus) Electrode pH related to the PCO2 by modified Henderson-Hasselbalch equation. PCO2 Electrode - Severinghaus e. 2). A systematic experimental and theoretical assessment of the Severinghaus Pco 2 electrode has been made with gas, water and blood samples, together with a study of the response dynamics of the apparatus. A study of the Radiometer "Severinghaus" Pco2 electrode has been made in order to investigate its stability and reproducibility when exposed to a series of inknown gas samples of various carbon dioxide concentrations. Using two TCM4 simultaneously in the first study, allowed one electrode to remain unchanged at 44°C while the temperature of the other electrode was increased every half hour (39, 40, 41, 42 and 44°C) ( Aug 21, 2021 · Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable Apr 9, 2024 · Clark and Severinghaus electrodes enabled the breakthrough for transcutaneous O2 and CO2 monitoring, respectively, and in the last twenty years, many innovations have been introduced as alternatives to overcome their limitations. Jun 28, 2016 · The monitoring of partial pressures of the blood gases carbon dioxide (pCO2) and oxygen (pO2) is of great importance in clinical diagnostics. The permeating CO 2 acidified the water film surrounding the electrode, and this produced a potential difference relative to the reference electrode (12). 1. Once inside, the CO2 finds itself in an aqueous solution. The Severinghaus or carbon dioxide electrode is a modified pH electrode in contact with sodium bicarbonate solution and separated from the blood specimen by a rubber or Teflon semi- permeable membrane. 2004 Nov;97 (5):1599-600. 17px bapk9s sr8 ad0o 2sa du vfet nsz3h6 dtqyx3 dub