Novel Sensor for Measurement of Blood Oxygenation

描述(由申请人提供)：通过准确和持续地监测大脑氧合，可以帮助管理严重的创伤性脑损伤等危及生命的急性神经疾病。然而，目前的监测系统是侵入性的，需要插入颈内静脉球或直接将探头插入大脑。虽然风险相对较低，但持续的颈静脉球部监测在技术上是困难的。近红外光谱学是一种无创监测脑血氧含量的方法，前景看好，但尚未提供成人的定量测量。目前尚无准确、无创、连续的脑血氧监测系统。我们提出了一种新型的光声传感器，并在体外和体内进行了测试，该传感器直接从上矢状窦准确而连续地测量血液氧合，由于光声技术的高分辨率，这种结构可以很容易地定位。光声技术是基于激光脉冲产生的超声波(光声)波，并由灵敏的声学换能器检测这些波。血氧的光声监测利用氧合和脱氧血红蛋白在近红外光谱范围内的光吸收系数的公认差异。在我们目前的NIH R21项目中(在PA-98-050计划公告的支持下，旨在开发包括光声脑监测在内的创新技术)，我们设计、建造并测试了用于准确监测脑血氧的便携式、非侵入性光声系统。我们在体外和体内(绵羊)的研究表明：(1)光声波的参数与血液氧合呈线性关系；(2)使用特殊设计的换能器和光声探测器，即使厚骨的光声衰减也能进行灵敏检测；以及(3)这项技术可以高精度地测量血液氧合。在这项拨款申请中，我们建议通过临床测试来进一步开发这种传感器。该项目的具体目标是：(1)在身体上评估传感器；(2)开发一种在志愿者体内在线计算血氧饱和度的算法；(3)在第二组志愿者身上验证传感器的性能。到该项目结束时，该传感器将得到充分开发，以允许进行多中心临床评估。除了大脑监测外，该传感器还有可能用于其他器官的局部非侵入性血氧测量。

DESCRIPTION (provided by applicant): Management of acute, life-threatening neurologic illnesses, such as severe traumatic brain injury, is facilitated by accurate and continuous monitoring of cerebral oxygenation. However, current monitoring systems are invasive, requiring either cannulation of the internal jugular venous bulb or insertion of a probe directly into the brain. Although relatively low-risk, continuous jugular venous bulb monitoring is technically arduous. Near-infrared spectroscopy, a noninvasive method of monitoring cerebral blood oxygenation, is promising, but has yet to provide quantitative measurement in adults. At present there is no system for accurate, non-invasive, and continuous monitoring of cerebral blood oxygenation. We proposed and performed in vitro and in vivo testing of a novel optoacoustie sensor that accurately and continuously measures blood oxygenation directly from the superior sagittal sinus, a structure that can easily be localized due to the high resolution of the optoacoustic technique. The optoacoustic technique is based on generation of ultrasonic (optoacoustic) waves by laser pulses and detection of these waves by a sensitive acoustic transducer. Optoacoustic monitoring of blood oxygenation utilizes well-established differences in the optical absorption coefficients of oxy- and deoxyhemoglobin in the near-infrared spectral range. During our current NIH R21 project (supported under Program Announcement PA-98-050 directed at the development of innovative technologies including photoacoustic brain monitoring), we designed, built, and tested a portable, noninvasive optoacoustic system for accurate monitoring of cerebral blood oxygenation. Our in vitro and in vivo (in sheep) studies demonstrated that: (1) the parameters of the optoacoustic waves are linearly dependent on blood oxygenation; (2) the use of specially designed transducers and optoacoustic probes allows sensitive detection despite optical and acoustic attenuation by thick bone; and (3) this technique can measure blood oxygenation with high accuracy. In this grant application, we propose to further develop this sensor by testing it clinically. The specific aims of the project are: (1) to evaluate the sensor in cadavers; (2) to develop an algorithm for calculating oxygen saturation on-line in vivo in volunteers; and (3) to validate the sensor performance in a second group of volunteers. By the end of the project the sensor will be developed sufficiently to permit multi-center clinical evaluation. In addition to brain monitoring, the proposed sensor can potentially be used for local non-invasive measurement of blood oxygenation in other organs.