['We sought to evaluate the parameters of CO2 transport during the administration of acetazolamide in order to assess the role of carbonic anhydrase in CO2 transport.', 'The partial pressure of carbon dioxide in tissue (PtCO2), arterial blood (PaCO2) and end-tidal gas (PETCO2) were monitored to study the correlation between PaCO2, PtCO2 and PETCO2 in spontaneously breathing healthy volunteers after the intravenous administration of acetazolamide 6 mg kg-1.', 'At 60 min after the administration of acetazolamide, the PtCO2 peaked at more than 60 mmHg, and although it decreased by 90 min, it then remained stable above the baseline value. The PaCO2 did not change and the PETCO2 decreased significantly. The changes in PtCO2 were greater than those of either PaCO2 or PETCO2. The minute ventilation increased progressively throughout the study.'] Does gastrotonometry represent dramatic increase in PcO2 after acetazolamide administration?