Mordon Serge, Rochon Philippe, Dhelin Guy, Lesage Jean Claude
INSERM (French National Institute of Health), Lille, France.
Lasers Surg Med. 2005 Oct;37(4):301-7. doi: 10.1002/lsm.20238.
Laser irradiation induces blood coagulation by heating of blood components. It is a complex phenomenon which encompasses a variety of processes, such as cell shape modification, cell membrane rupture, protein denaturation, aggregation, and finally blood gelation. An in vitro study was performed to investigate heating temperatures leading to transformation of blood and to have a better understanding of the dynamics of temperature dependent modifications of blood in the near-infrared.
STUDY DESIGN/MATERIALS AND METHODS: Slow heating of whole blood and hemolized blood was performed using a specific optical chamber. Eight hundred and five and 940 nm light transmission of blood was measured as a function of time during heating at various temperatures (60-75 degrees C).
During heating of whole blood, three phases were clearly identified. For hemolized blood, only phase 3 was present. For whole blood, the duration of each phase was correlated to blood temperature. A temporary increase of transmission was observed during heating with a maximum at 65 degrees C. The analysis of the dynamics of temperature dependent modifications of blood are consistent with cell shape modification, denaturation, and aggregation of blood, resulting in the formation of an aqueous gel-matrix.
"Slow" vessel heating which is now proposed as the optimal mechanism for permanent vessel closure should be reconsidered in terms of our results. In that particular case, the optical coefficients of blood could be different from those expected. In case of a large blood vessel, this could be an advantage since a "temporary" higher transmission of light could lead to a more homogeneous heating of the blood vessel. In case of a small blood vessel, this phenomenon could lead to a collateral damage of the skin.
激光照射通过加热血液成分诱导血液凝固。这是一个复杂的现象，涵盖了多种过程，如细胞形状改变、细胞膜破裂、蛋白质变性、聚集，最终导致血液凝胶化。进行了一项体外研究，以探究导致血液转变的加热温度，并更好地理解近红外光下血液温度依赖性变化的动力学。
研究设计/材料与方法：使用特定的光学腔对全血和溶血进行缓慢加热。在不同温度（60 - 75摄氏度）下加热过程中，测量了805和940纳米波长的血液光透射率随时间的变化。
在全血加热过程中，清晰地识别出三个阶段。对于溶血，仅存在阶段3。对于全血，每个阶段的持续时间与血液温度相关。在加热过程中观察到透射率暂时增加，在65摄氏度时达到最大值。对血液温度依赖性变化动力学的分析与细胞形状改变、变性和血液聚集一致，导致形成水凝胶基质。
根据我们的结果，目前被提议作为永久性血管闭合最佳机制的“缓慢”血管加热应重新考虑。在那种特殊情况下，血液的光学系数可能与预期的不同。对于大血管而言，这可能是一个优势，因为“暂时”更高的光透射率可能导致血管更均匀地受热。对于小血管，这种现象可能导致皮肤的附带损伤。
