In this randomized crossover trial , 14 consecutive patients ( 7 in each arm ) undergoing major spine surgery , under a background anesthetic of propofol ( 75 to 125 mcg/kg/min ) and remifentanil ( 0.1 to 0.2 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 ) .