Mucosal tissue oxygenation of the porcine jejunum during normothermic cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has been associated with intestinal tissuehypoxia, but direct measurements of mucosal oxygenation have not beenperformed. In anaesthetized pigs, jejunal mucosal oxygen tension andmicrovascular haemoglobin oxygen saturation were measured by a Clark- typeelectrode and tissue reflectance spectrophotometry. In pigs, normothermicCPB with systemic oxygen transport equivalent to baseline values wasperformed. In control animals, mucosal oxygen tension and mucosalhaemoglobin oxygen saturation were mean 5.01 (SD 1.08) kPa and 38.0 (2.3)%,respectively. CPB was associated with a decrease in mucosal oxygen tensionto 2.26 (1.21) kPa, decrease in mucosal microvascular haemoglobin oxygensaturation to 26.0 (3.9)% and appearance of oscillations in mucosalmicrovascular haemoglobin oxygen saturation. With CPB, arterial lactateconcentrations increased from 1.77 (1.37) to 3.52 (1.58) mmol litre-1, buttransvisceral lactate and splanchnic venous-arterial carbon dioxide tensiongradients remained unchanged. Our results support the concept that CPB isassociated with diminished oxygenation of intestinal mucosa that isprobably caused by regional redistribution.