Impact of sevoflurane anesthesia on cerebral blood flow in children younger than 2 years

Abstract

To assess the impact of sevoflurane and anesthesia-induced hypotension on cerebral blood flow (CBF) in children younger than 2 years. Inhalational induction with sevoflurane is the most commonly used technique in young children. However, the effect of sevoflurane on cerebral perfusion has been only studied in adults and children older than 1 year. The purpose of this study is to assess the impact of sevoflurane anesthesia on CBF in neonates and infants, using transcranial Doppler (TCD) sonography. Children younger than 2 years, ASA I or II, for abdominal or orthopedic surgery were included. Induction of anesthesia was started by sevoflurane 6% and maintained with an expired fraction of sevoflurane 3%. Mechanical ventilation was controlled to maintain an end tidal CO(2) around 39 mmHg. CBF was assessed by measuring the velocities (systolic velocity SVmca, diastolic velocity DVmca and mean velocity MVmca) in the proximal segment of the middle cerebral artery (mca) in children awake and then 15 min after induction. Mean arterial pressure (MAP) variation was noted. One hundred and thirteen children were included. We observed a significant decrease in MAP (-30%). DVmca decreased and pulsatility index increased significantly after induction. Subgroup analysis according to age showed that in infants older than 6 months, despite a significant reduction in MAP, there was no change in CBF velocity (CBFV) as measured by TCD sonography, until MAP dropped below 40% of baseline. In infants younger than 6 months, a significant decrease in MAP was observed which was associated with a significant variation in CBFV. In this population, when CBFV start to decrease, MAP under sevoflurane anesthesia was 38 mmHg or -20% from baseline value. Our results are in favor of a reduction in CBF after induction with sevoflurane in children younger than 6 months. This population is more sensitive to MAP decrease than older children because of a lower limit of cerebral autoregulation, and this limit may be 38 mmHg with sevoflurane anesthesia.