Atropine reversal of hypercarbia during enflurane anaesthesia

Atropine was given i.v. to 35 spontaneously breathing healthy adults anaesthetized with enflurane to determine if it would reduce PaCO2 by improving gas exchange. Five minutes after administration of atropine, PaCO2 decreased from mean 7.18 to 6.65 kPa (-7%), while mean VE increased from 4.8 to 6.1 litre min-1 (+27%). These changes were maintained 15 min later in the 20 patients studied at that time. Older and more obese patients showed a more significant change. Respiratory frequency and PaO2 did not alter.