Continuous Transcutaneous Gas Monitoring in Adults on Regular Dialysis Treatment

Abstract

We tested a transcutaneous (tc) oxygen (O₂) and carbon dioxide (CO_z) sensor in 15 normal adults and in 20 patients on regular dialysis treatment (RDT). We compared the tc gas values (ptcO₂, PtcCO₂) with the gas tension values in arterial blood samples (PaO₂, PaCO₂), in normal adults and in RDT-patients at the end of a 30-min test and six times during RDT. During the test, PtcO₂ correlated with PaO₂ both in normal adults (r 0.72p<0.01) and in RDT patients (r 0.41 p<0.05). PtcCO₂ correlated with PaCO₂ (r 0.59 in normal adults and r 0.76 in RDT). During 14 acetate dialyses the changes were expressed as %Δ from time 0. %Δ PaO₂ was – 12.7 at 60 min, + 4.8 at 240 min; %Δ PtcO₂ – 6.0 at 60 min, + 9.7 at 240 min; %Δ PaCO₂ – 17.7 at 240 min, – 1.8 1 h later; %Δ PtcCO₂ was – 15.8 at 240 min, – 3.2 1 h later. Both in normal adults and in RDT, patients there was a good relationship between PtcCO₂ and PaCO₂ values. In normal adults the absolute PtcO₂ values were always lower than PaO₂ (– 14.4± 10 mmHg); in RDT-patients this difference was more pronounced (– 27.6± 15.1) and is probably attributable to the lower Hb levels (6.7± 1.1 vs 12.4± 1.2). During RDT the pattern was the same between tc and gas tension values. The tc-sensor seems to be useful in continuous monitoring, especially in acetate dialysis and/or in patients suspected of developing hypoxemia, but it cannot replace direct blood gas measurements in arterial blood samples.