Rajaram Ajay, Milej Daniel, Suwalski Marianne, Yip Lawrence C M, Guo Linrui R, Chu Michael W A, Chui Jason, Diop Mamadou, Murkin John M, St Lawrence Keith
Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada.
Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada.
Biomed Opt Express. 2020 Sep 29;11(10):5967-5981. doi: 10.1364/BOE.404101. eCollection 2020 Oct 1.
During cardiac surgery with cardiopulmonary bypass (CPB), adequate maintenance of cerebral blood flow (CBF) is vital in preventing postoperative neurological injury - i.e. stroke, delirium, cognitive impairment. Reductions in CBF large enough to impact cerebral energy metabolism can lead to tissue damage and subsequent brain injury. Current methods for neuromonitoring during surgery are limited. This study presents the clinical translation of a hybrid optical neuromonitor for continuous intraoperative monitoring of cerebral perfusion and metabolism in ten patients undergoing non-emergent cardiac surgery with non-pulsatile CPB. The optical system combines broadband near-infrared spectroscopy (B-NIRS) to measure changes in the oxidation state of cytochrome c oxidase (oxCCO) - a direct marker of cellular energy metabolism - and diffuse correlation spectroscopy (DCS) to provide an index of cerebral blood flow (CBFi). As the heart was arrested and the CPB-pump started, increases in CBFi (88.5 ± 125.7%) and significant decreases in oxCCO (-0.5 ± 0.2 µM) were observed; no changes were noted during transitions off CPB. Fifteen hypoperfusion events, defined as large and sustained reductions in CPB-pump flow rate, were identified across all patients and resulted in significant decreases in perfusion and metabolism when mean arterial pressure dropped to 30 mmHg or below. The maximum reduction in cerebral blood flow preceded the corresponding metabolic reduction by 18.2 ± 15.0 s. Optical neuromonitoring provides a safe and non-invasive approach for assessing intraoperative perfusion and metabolism and has potential in guiding patient management to prevent adverse clinical outcomes.
在体外循环（CPB）心脏手术期间，充分维持脑血流量（CBF）对于预防术后神经损伤至关重要，例如中风、谵妄、认知障碍。CBF降低到足以影响脑能量代谢的程度会导致组织损伤及随后的脑损伤。目前手术期间的神经监测方法有限。本研究展示了一种混合光学神经监测仪的临床应用，该监测仪用于对10例接受非搏动性CPB非急诊心脏手术的患者进行术中脑灌注和代谢的连续监测。该光学系统结合了宽带近红外光谱（B-NIRS）以测量细胞色素c氧化酶（oxCCO）氧化状态的变化（细胞能量代谢的直接标志物）以及扩散相关光谱（DCS）以提供脑血流量指数（CBFi）。随着心脏停搏且CPB泵启动，观察到CBFi增加（88.5±125.7%）且oxCCO显著降低（-0.5±0.2 μM）；在脱离CPB的过程中未观察到变化。在所有患者中识别出15次低灌注事件，定义为CPB泵流速大幅且持续降低，当平均动脉压降至30 mmHg或更低时，导致灌注和代谢显著降低。脑血流量的最大降低比相应的代谢降低提前18.2±15.0秒。光学神经监测为评估术中灌注和代谢提供了一种安全且无创的方法，并且在指导患者管理以预防不良临床结局方面具有潜力。
