ON-LINE P o 2 AND P N 2 o ANALYSIS WITH AN IN VIVO CATHETER ELECTRODE

Abstract

A technique was developed for the in vivo determination of PO2 and PN2O with a catheter electrode using double-pulse polarography. The method was evaluated in dog studies comparing readings from the electrode with those from a mass spectrometer employing an in vivo probe. The oxygen readings obtained from the catheter electrode were also compared with values obtained by conventional blood-gas analysis. Good agreement was observed between the electrode and the mass spectrometer for both PO2 and PN2O. Similar agreement was found between the electrode readings and blood-gas analysis for PO2. In the presence of halothane, the electrode over-read for both PO2 and PN2O; a remedy is suggested. The in vivo electrode provides an effective, less expensive, alternative to the mass spectrometer for the on-line measurement of PO2 and PN2O in vivo.

The effect of hip resurfacing on oxygen concentration in the femoral head

“…Nitrous oxide is not metabolised, any reduction in its concentration after blood flow reduction being a result of diffusion. In our study we applied a modification of the technique described by Brooks et al 22 Silver (Ag) electrodes, when correctly polarised, generate a current, which is proportional to the concentration of the target gas. Selecting the correct polarisation voltage (with respect to a silver/silver chloride (Ag/AgCI) reference electrode), selects the gas to which an electrode is sensitive.…”

“…The method was advanced further in an in vitro study by Hahn et al, 21 who investigated gas concentrations in electrolyte solutions. The first in vivo application of intravascular electrodes in anaesthetised dogs was reported by Brooks et al 22 Further modifications allowed oxygen and nitrous oxide concentrations to be measured in muscle and intervertebral disc tissue [23][24][25][26][27] in humans. To our knowledge, however, these have not previously been measured in bone.…”

Analytical Bioelectrochemistry

“…Numerous redox molecules, either metabolites or drugs, may be determined in biological samples either directly or after an extraction procedure [3,4]. Particularly miniaturized electrodes using carbon fibers or paste may be implanted and allow the continuous monitoring of some metabolites and drugs in neuronal tissues or arteries [5][6][7][8]. Some clinical instruments, such as blood chloride meters, use such Ag generated coulometries.…”

Tutorial ReviewElectrochemical analysis of clinicalblood-gases, gases and vapours

“…Since the simultaneous O 2 and N 2 O reduction processes did not interfere with each other, the current obtained from the second pulse was simply an addition of the O 2 and N 2 O reducing currents. 87 An appropriate computer algorithm was therefore employed to deconvolute the O 2 and N 2 O current-concentration contributions. The determination of the appropriate duty cycle to employ under these experimental conditions can be obtained from analysis of the digital pulse simulation procedure described in the computer model simulation section.…”