Selvaraj Nandakumar, Scully Christopher G, Shelley Kirk H, Silverman David G, Chon Ki H
Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:5499-502. doi: 10.1109/IEMBS.2011.6091403.
The present study was designed to investigate can the amplitude modulation (AM) of Photoplethysmogram (PPG) be used as an indicator of blood loss and if so what is the best PPG probe site. PPG from ear, finger and forehead probe sites, standard ECG, and Finapres blood pressure waveforms were continuously recorded from 8 healthy volunteers during baseline, blood withdrawal of 900 ml followed by the blood reinfusion. The instantaneous amplitude modulations present in heart rate (AM(HR)) and breathing rate (AM(BR)) band frequencies of PPG were extracted from high-resolution time-frequency spectrum. HR and pulse pressure showed no significant changes during the protocol. The AM(HR) significantly (P<0.05) decreased at 100 ml through 900 ml blood loss from ear and finger probe sites. The mean percent decrease in AM(HR) at 900 ml blood loss compared to baseline value was 45.2%, 42.0%, and 42.3% for ear, finger and forehead PPG signals, respectively. In addition, significant increases in AM(BR) were found due to blood loss in ear and finger PPG signals. Even without baseline AM(HR) values, 900 ml blood loss detection was shown possible with specificity and sensitivity both 87.5% from ear PPG signals. The present technique has great potential to serve as a valuable tool in the intraoperative and trauma settings to detect hemorrhage.
本研究旨在调查光电容积脉搏波（PPG）的幅度调制（AM）是否可作为失血的指标，若可以，最佳的PPG探头部位是什么。在基线期、抽取900ml血液然后再输血的过程中，连续记录了8名健康志愿者耳部、手指和前额探头部位的PPG、标准心电图以及Finapres血压波形。从高分辨率时频谱中提取PPG心率（AM(HR)）和呼吸率（AM(BR)）频段中存在的瞬时幅度调制。在该实验过程中，心率和脉压无显著变化。从耳部和手指探头部位失血100ml至900ml时，AM(HR)显著降低（P<0.05）。与基线值相比，失血900ml时耳部、手指和前额PPG信号的AM(HR)平均下降百分比分别为45.2%、42.0%和42.3%。此外，发现耳部和手指PPG信号因失血导致AM(BR)显著增加。即使没有基线AM(HR)值，耳部PPG信号检测900ml失血的特异性和敏感性均为87.5%，表明这种检测是可行的。本技术在术中及创伤情况下作为检测出血的有价值工具具有巨大潜力。
