Effects of haemodilution on the optical properties of blood during coagulation studied by optical coherence tomography

We report an investigation of the effects of blood dilution with hypertonic (7.5 %) and normal (0.9 %) saline on its optical properties during coagulation in vitro using optical coherence tomography. The light penetration depth and attenuation coefficient are obtained from the dependences of reflectance on the depth. Normal whole blood has served as the control group. The average coagulation time is equal to 420 +/- 16, 418 +/- 16 and 358 +/- 14 s with blood volume replacement of 2 %, 11 %, and 20 % by 0.9 % normal saline, respectively. With 2 %, 11% and 20% blood volume replacement with 7.5 % hypertonic saline, the average coagulation time is 422 +/- 17, 1160 +/- 45 and 1730 +/- 69 s, respectively. For normal whole blood, the average coagulation time amounts to 425 +/- 19 s. it is shown that dilution with normal saline has a procoagulant effect when it replaces 20 % of blood volume, and hypertonic saline has an anticoagulant effect if it replaces 11 % or more of blood volume. It is concluded that optical coherence tomography is a potential technique to quantify and monitor the liquid-gel transition during the coagulation process of blood diluted by normal and hypertonic saline.