Kyriacou P A, Moye A R, Gregg A, Choi D M, Langford R M, Jones D P
Department of Medical Electronics & Physics, St. Bartholomew's & The Royal London School of Medicine & Dentistry, Queen Mary & Westfield College, UK.
Med Biol Eng Comput. 1999 Sep;37(5):639-43. doi: 10.1007/BF02513360.
The monitoring of arterial blood oxygen saturation in patients with compromised peripheral perfusion is often difficult, because conventional non-invasive techniques such as pulse oximetry (SpO2) can fail. Poor peripheral circulation commonly occurs after major surgery including cardiopulmonary bypass. The difficulties in these clinical situations might be overcome if the sensor were to monitor a better perfused central part of the body such as the oesophagus. A new oesophageal photoplethysmographic (PPG) probe and an isolated processing system have been developed to investigate the pulsatile signals of anaesthetised adult patients undergoing routine surgery. Measurements were made in the middle third of the oesophagus, 25 cm to 30 cm from the upper incisors. The AC PPG signals are sampled by a data acquisition system connected to a laptop computer. The signals recorded correspond to infrared and red AC PPGs from the middle third oesophagus and the finger. Preliminary results from 20 patients show that good quality AC PPG signals can be measured in the human oesophagus. The ratio of the oesophageal to finger AC PPG amplitudes was calculated for the infrared and red wavelengths for each patient. The mean (+/- standard deviation) of this ratio was 2.9 +/- 2.1 (n = 19) for the infrared wavelength and 3.1 +/- 2.4 (n = 16) for the red wavelength. The red and infrared wavelengths used are appropriate for pulse oximetry and this investigation indicates that the mid-oesophagus may be a suitable site for the reliable monitoring of SpO2 in patients with poor peripheral perfusion.
对于外周灌注受损的患者，监测动脉血氧饱和度往往很困难，因为传统的非侵入性技术，如脉搏血氧饱和度测定法（SpO2）可能会失效。外周循环不良常见于包括体外循环在内的大手术后。如果传感器能够监测身体灌注较好的中心部位，如食管，这些临床情况中的困难或许可以克服。已开发出一种新型食管光电容积脉搏波描记法（PPG）探头和一个独立的处理系统，以研究接受常规手术的成年麻醉患者的搏动信号。测量在食管中三分之一处进行，距离上切牙25厘米至30厘米。交流PPG信号由连接到笔记本电脑的数据采集系统进行采样。记录的信号对应于来自食管中三分之一处和手指的红外和红色交流PPG信号。20例患者的初步结果表明，可在人体食管中测量到高质量的交流PPG信号。计算了每位患者红外和红色波长下食管与手指交流PPG振幅的比值。该比值的平均值（±标准差）在红外波长下为2.9±2.1（n = 19），在红色波长下为3.1±2.4（n = 16）。所使用的红色和红外波长适用于脉搏血氧饱和度测定，并且该研究表明食管中部可能是对外周灌注不良患者进行可靠SpO2监测的合适部位。
