Heart rate , mean arterial pressure ( MAP ) , hemoglobin oxygen saturation ( SpO2 ) , respiratory rate , tidal volume ( VT ) and pressure of end-tidal carbon dioxide ( PETCO2 ) were recorded at the time before induction ( T0 ) , 30 min before the end of surgery ( T1 ) , 20 min before the end of surgery ( T2 ) , 15 min before the end of surgery ( T3 ) , 10 min before the end of surgery ( T4 ) , the end of surgery ( T5 ) , extubation ( T6 ) , 5 min after transferal into post-anesthesia care unit ( PACU ) ( T7 ) , 1 h after surgery ( T8 ) , extubation time , length of PACU stay , fentanyl consumption and adverse events were all recorded .