Impact of sevoflurane anesthesia on brain oxygenation in children younger than 2 years.
OBJECTIVE
To assess the impact of sevoflurane and anesthesia-induced hypotension on brain oxygenation in children younger than 2 years.


BACKGROUND
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 was to assess the impact of sevoflurane anesthesia on brain oxygenation in neonates and infants, using near-infrared spectroscopy.


METHODS
Children younger than 2 years, ASA I or II, scheduled 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 adjusted to maintain an endtidal CO2 around 39 mmHg. Brain oxygenation was assessed measuring regional cerebral saturation of oxygen (rSO2 c), measured by NIRS while awake and 15 min after induction, under anesthesia. Mean arterial pressure (MAP) variation was recorded.


RESULTS
Hundred and ninety-five children were included. Anesthesia induced a significant decrease in MAP (-27%). rSO2 c increased significantly after induction (+18%). Using children age for subgroup analysis, we found that despite MAP reduction, rSO2 c increase was significant but smaller in children ≤ 6 months than in children >6 months (≤ 6 months: rSO2 c = +13%, >6 months: rSO2 c = +22%; P < 0.0001). Interindividual comparison showed that, during anesthesia at steady-state with comparable CMRO2, rSO2 c values were significantly higher when MAP was above 36 mmHg. And the higher the absolute MAP value during anesthesia was, the higher the rSO2 c was. We observed a rSO2 c variation ≤ 0 in 21 patients among the 195 studied, and the majority of these patients were younger than 6 months (n = 19). No increase or decrease of rSO2 c during anesthesia despite reduction of CMRO2 can be explained by a reduction of oxygen supply. Using the ROC curves, we determined that the threshold value of MAP under anesthesia, associated with rSO2 c variation ≤ 0%, was 39 mmHg in all the studied population (AUC: 0.90 ± 0.02; P < 0.001). In children younger than 6 months, this value of MAP was 33 mmHg, and 43 mmHg in children older than 6 months.


CONCLUSIONS
Despite a significant decrease of MAP, 1 MAC of sevoflurane induced a significant increase in regional brain oxygenation. But subgroup analysis showed that MAP decrease had a greater impact on brain oxygenation, in children younger than 6 months. According to our results, MAP value during anesthesia should not go under 33 mmHg in children ≤6 months and 43 mmHg in children >6 months, as further changes in MAP, PaCO2 or hemoglobin during anesthesia may be poorly tolerated by the brain.
Department of Pediatric Anesthesia, Hôpital Mère-Enfant, Lyon, France; Department of Pediatric Anesthesia, Hôpital Sainte Justine, Montréal, QC, Canada.
Ossam
O
Rhondali
Simon
S
Juhel
Sylvain
S
Mathews
Quentin
Q
Cellier
François-Pierrick
FP
Desgranges
Aurélie
A
Mahr
Mathilde
M
De Queiroz
Agnès
A
Pouyau
Khalid
K
Rhzioual-Berrada
Dominique
D
Chassard
D000375:Aging / Q000502:physiology; D000769:Anesthesia, Inhalation / Q000009:adverse effects*; D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D062186:Arterial Pressure / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008738:Methyl Ethers / Q000009:adverse effects*; D010101:Oxygen Consumption / Q000187:drug effects*; D000077149:Sevoflurane; D019265:Spectroscopy, Near-Infrared
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane
anesthesia; blood pressure/drug effects; brain oxygenation/drug effects; cerebrovascular circulation/drug effects; infant; inhalation; near-infrared spectroscopy