In this randomized crossover trial , @ consecutive patients ( @ in each arm ) undergoing major spine surgery , under a background anesthetic of propofol ( @ to @ mcg/kg/min ) and remifentanil ( @ to @ mcg/kg/min ) , were randomly assigned to receive the sequence of inhalational agents studied : either DES-SEVO ( desflurane followed by sevoflurane ) ; or SEVO-DES ( sevoflurane followed by desflurane ) .