Conjunctival oxygen tension monitoring during liver transplantation

Conjunctival oxygen tension has been noted in animal studies to correlate with oxygen delivery. In order to assess this relationship in man, we compared the proportional changes in conjunctival oxygen tension with those in oxygen delivery that occur on the placement and release of the inferior vena caval clamps in 10 patients during orthotopic liver transplantation without veno-venous bypass. We also examined the changes in mixed venous oxygen saturation at these times. We found a statistically significant correlation between both parameters and oxygen delivery (p < 0.001). However, analysing the data on a Bland and Altman plot of difference versus mean, it is our conclusion that the variation in the data is such that neither conjunctival oxygen tension nor mixed venous oxygen saturation can be used clinically to predict the changes in oxygen delivery that occur during liver transplantation.