CARBON-DIOXIDE (CO2) HOMEOSTASIS DURING ORTHOTOPIC LIVER-TRANSPLANTATION

Changes in arterial-to-end tidal carbon dioxide partial pressure gradi ent (Pa-ETCO2), CO2 excretion (VCO2) and physiological dead space (DSP hys) were measured in 22 patients undergoing orthotopic liver transpla ntation (OLT) with venovenous bypass during the anhepatic phase. Durin g the preanhepatic phase Pa-ET CO2, VCO2 and DSPhys were within the ra nge found during general anaesthesia, while CO was higher than normal, as usually found in end-stage cirrhotic patients. Significant changes during the anhepatic phase were widening of Pa-ET CO2 and DSPhys and reduction of VCO2. Pa-ET CO2 and DSPhys increased further early after reperfusion of the graft (9.6 4 mmHg, p 0.001 vs A and 2.7 0.7 mi kg-l , p 0.001 vs A, respectively) together with a sharp rise of VCO2. The Pa-ET CO2 and DSPhys returned to normal limits at the completion of su rgery, while VCO2 rose to significant levels, increased DSAlv Seems to be the most likely explanation of the widening of the Pa-ET CO2 in pr esence of an increased DSPhys As a consequence, the wide changes in Pa -ET CO2 recorded during the anhepatic phase and early after reperfusio n of the graft make ETCO2 an unreliable monitor of PaCO2 and hence of ventilatory requirements during the various phases of OLT. On the othe r hand, we did not find the trend of VCO2 following revascularization of the graft as a reliable monitor of the immediate functional recover y of the newly grafted liver.