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 ASA NEWSLETTER
 
 
September 2002
Volume 66
Number 9
 

Respiratory Monitoring • Blood Gases
Early 1954   Stow described his CO2 electrode but failed to develop it further.


Richard Stow, M.D. (1916- )




Stow CO2 Electrode
A. rubber membrane;
B. glass & Ag/AgCl electrodes;
C. rubber band;
D. leads;
H. Tygon enamel strip;
J. Tygon paint;
K. Ag tip.
     
Late 1954   Clark designed his PO2 electrode, just two years after his other "first": a bubble oxygenator for humans. His Clark-Yellow Springs polarographic PO2 electrode analyzed oxygen broken down at a cathode beyond a semi-permeable membrane. Altered KCl conductivity allowed current passing between a Ag anode an a Au-Pt cathode to be proportional to O2 concentration.


Leland C. Clark, Jr., Ph.D. (1918- )



Clark-Yellow Springs polarographic PO2 electrode
     
1956   Frumin & Lee's Autoanestheton ventilator monitored EtCO2 and varied tidal volume to hold a preset CO2.


Autoanestheton
     
1958   Severinghaus developed a complete blood gas apparatus by combining his practical version of Stow's CO2 electrode with Clark's PO2 electrode. The first commercial blood gas system featured a cuvette with stirrer for Clark's PO2 electrode and a Stow-Severinghaus electrode.


John W. Severinghaus, M.D. (1922- )




Earliest commercial blood gas system with Clark & Stow- Severinghaus electrodes.
     
1960s   Use of volume ventilators and Astrup blood gas apparatus for pCO2 control led to widespread ICU-use of respirometers, which supplanted industrial gas meters & huge water-seal Collins-type spirometers.


Respirometers
     
1975   Galvanic electrode oxygen analyzers were introduced. They reduced O2 at a Au electrode while oxidizing a Pb electrode. The potential difference is proportional to the O2 diffusion rate.


Galvanic electrode
oxygen analyzer
     
1981   The Dräger DPM-S was the first monitor for sustained positive / high / subatmospheric pressures or failure to reach minimum ventilation pressure (e.g., disconnection).


Dråger DPM-S

 


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