Rhondali Ossam, Juhel Simon, Mathews Sylvain, Cellier Quentin, Desgranges François-Pierrick, Mahr Aurélie, De Queiroz Mathilde, Pouyau Agnès, Rhzioual-Berrada Khalid, Chassard Dominique
Department of Pediatric Anesthesia, Hôpital Mère-Enfant, Lyon, France; Department of Pediatric Anesthesia, Hôpital Sainte Justine, Montréal, QC, Canada.
Paediatr Anaesth. 2014 Jul;24(7):734-40. doi: 10.1111/pan.12397. Epub 2014 Apr 2.
OBJECTIVE/AIM: To assess the impact of sevoflurane and anesthesia-induced hypotension on brain oxygenation 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 was to assess the impact of sevoflurane anesthesia on brain oxygenation in neonates and infants, using near-infrared spectroscopy.
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.
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.
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.
评估七氟醚和麻醉诱导的低血压对2岁以下儿童脑氧合的影响。
七氟醚吸入诱导是幼儿最常用的技术。然而，七氟醚对脑灌注的影响仅在成人和1岁以上儿童中进行过研究。本研究的目的是使用近红外光谱评估七氟醚麻醉对新生儿和婴儿脑氧合的影响。
纳入年龄小于2岁、美国麻醉医师协会（ASA）分级为I或II级、计划进行腹部或骨科手术的儿童。麻醉诱导开始时使用6%的七氟醚，维持时使用3%的七氟醚呼气末浓度。调整机械通气以维持呼气末二氧化碳分压在39 mmHg左右。在清醒状态下以及麻醉诱导后15分钟，通过近红外光谱测量局部脑氧饱和度（rSO2 c）来评估脑氧合。记录平均动脉压（MAP）变化。
共纳入195名儿童。麻醉导致MAP显著降低（-27%）。诱导后rSO2 c显著升高（+18%）。按儿童年龄进行亚组分析，我们发现尽管MAP降低，但rSO2 c升高在≤6个月的儿童中显著但幅度小于>6个月的儿童（≤6个月：rSO2 c = +13%，>6个月：rSO2 c = +22%；P < 0.0001）。个体间比较显示，在麻醉稳态且脑代谢率（CMRO2）可比时，当MAP高于36 mmHg时，rSO2 c值显著更高。麻醉期间绝对MAP值越高，rSO2 c越高。在195名研究对象中，我们观察到21名患者的rSO2 c变化≤0，其中大多数患者年龄小于6个月（n = 19）。麻醉期间尽管CMRO2降低但rSO2 c无增加或减少不能用氧供应减少来解释。使用ROC曲线，我们确定在所有研究人群中，与rSO2 c变化≤0%相关的麻醉下MAP阈值为39 mmHg（曲线下面积：0.90±0.02；P < 0.001）。在小于6个月的儿童中，该MAP值为33 mmHg，在大于6个月的儿童中为43 mmHg。
尽管MAP显著降低，但1个最低肺泡有效浓度（MAC）的七氟醚可诱导局部脑氧合显著增加。但亚组分析表明，MAP降低对6个月以下儿童的脑氧合影响更大。根据我们的结果，≤6个月儿童麻醉期间MAP值不应低于33 mmHg，>6个月儿童不应低于43 mmHg，因为麻醉期间MAP、动脉血二氧化碳分压（PaCO2）或血红蛋白的进一步变化可能大脑耐受性较差。
