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目的通过检测不同程度缺氧时新生猪脑氧合的变化,研究脑缺氧程度-脑功能-脑损伤之间的规律。方法对15只新生猪检测脑组织血氧饱和度(Regional oxygen saturation,rSO_2),给新生猪机械通气吸入低浓度氧,造成脑 rSO_2不同进行分组。实验过程监测生理参数、脑电,脑损伤后72 h 进行海马 CA1区光镜及电镜检查。结果在缺氧至脑 rSO_2>40%的小猪组,缺氧后平均动脉压(Mean arterial pressure,MAP)为(56±0.00)mm Hg(1 mm Hg=0.133 kPa),血乳酸(2.3±1.2)mmol/L,脑电变化不明显,脑组织光镜、电镜无明显改变。在缺氧至脑 rSO_230%～40%时,MAP 为(73±8)mm Hg,血乳酸增高至(8.2±3.9)mmol/L,脑电观察的脑功能发生改变,但缺氧后有所恢复,脑组织光镜有缺血性改变,电镜表现为海马 CA1区神经元线粒体损伤。当缺氧至脑 rSO_2<30%时,MAP 为(35±0.00)mmHg,血乳酸增高至(12±2)mmol/L,脑电观察脑功能受损,部分在缺氧后难以恢复,光镜下细胞有空泡形成,破碎,海马 CA1区神经元线粒体严重损伤。结论在不同程度的缺氧下,当脑至 rSO_2 30%～40%时,新生猪出现脑损伤,当 rSO_2<30%,出现严重的脑损伤;rSO_2越低,脑功能、脑损害越重;无创近红外光谱检测到的脑组织 rSO_2可以在脑缺氧过程中反映脑损伤及损伤的程度。
Objective To study the regularity of cerebral hypoxia-brain function-brain damage by detecting the changes of cerebral oxygenation of neonatal pigs with different degrees of hypoxia. Methods Fifteen newborn pigs were tested for regional oxygen saturation (rSO_2), and newborns were exposed to low concentrations of oxygen by mechanical ventilation, resulting in differences in brain rSO_2. The physiological parameters of the experimental process monitoring, brain electrical injury, 72 h after the hippocampal CA1 area light and electron microscopy. Results The mean arterial pressure (MAP) after hypoxia was (56 ± 0.00) mm Hg (1 mm Hg = 0.133 kPa) and blood lactate (2.3 ± 1.2) mmol / L, EEG was not obvious, brain tissue light microscope, electron microscope no significant change. MAP was (73 ± 8) mm Hg and blood lactate increased to (8.2 ± 3.9) mmol / L after hypoxia to brain rSO_2 from 30% to 40%, but brain function changed after EEG observation, but after hypoxia Recovery, brain tissue light microscope ischemic changes, electron microscopy showed hippocampal CA1 neurons mitochondrial damage. When hypoxia to brain rSO_2 <30%, MAP was (35 ± 0.00) mmHg, blood lactate increased to (12 ± 2) mmol / L, brain function was impaired after EEG observation, Microscopically, the vacuoles formed and broken, and the mitochondria in hippocampal CA1 neurons were severely damaged. Conclusion Under different degrees of hypoxia, brain injury occurred in neonatal pigs when rSO 2 was 30% ~ 40%. When rSO_2 was less than 30%, severe brain injury occurred. The lower the rSO_2 was, the more brain function and brain damage occurred. The brain tissue rSO 2 detected by noninvasive NIR spectroscopy can reflect the degree of brain injury and injury in the process of cerebral hypoxia.