title: Optical aggregometry of red blood cells associated with the blood-clotting reaction in extracorporeal circulation support.
abstract: The aggregability of red blood cell (RBCs) is associated with the contribution of plasma proteins, such as fibrinogen and lipoproteids, to blood-clotting. Hence, we hypothesized that RBC aggregability reflects the blood-clotting reaction. A noninvasive optical monitoring method to measure RBC aggregability for the assessment of blood-clotting stage during mechanical circulatory support was developed. An in vitro thrombogenic test was conducted with a rotary blood pump using heparinized fresh porcine blood. Near-infrared laser light at a wavelength of 785 nm was guided by an optical fiber. The fibers for detecting incident, forward-, and backward-scattered light were fixed on the circuit tubing with an inner diameter of 1/4 inch. Because there is substantial RBC aggregation at low shear flow rates, a pulsatile flow was generated by controlling the pump rotational speed. The flow rate was changed from 0 to 8.5 L/min at a period of 40 s. The intensities of forward- and backward-scattered light changed dramatically when the flow stopped. The aggregability was evaluated by the increase ratio of the transmitted light intensity from the flow stopping in the low-flow condition. The experiment started when the anticoagulation was stopped by the addition of protamine into the circulating blood. Reduction in RBC aggregability was associated with a decrease in the amount of fibrinogen and the number of platelets. Continuous, noninvasive monitoring of thrombosis risk is possible using optical measurements combining pulsatile flow control of a rotary blood pump. RBC aggregometry is a potential label-free method for evaluating blood-clotting risk.
authors.affiliation: Artificial Organ Research Group, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, 305-8564, Ibaraki, Japan. sakota.ao@aist.go.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sakota
authors.affiliation: Artificial Organ Research Group, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, 305-8564, Ibaraki, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kosaka
authors.affiliation: Artificial Organ Research Group, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, 305-8564, Ibaraki, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishida
authors.affiliation: Artificial Organ Research Group, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, 305-8564, Ibaraki, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Maruyama
mesh_terms: D000818:Animals; D004903:Erythrocyte Aggregation / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology*; D005112:Extracorporeal Circulation; D013552:Swine
keywords: Aggregation; Blood-clotting reaction; Extracorporeal circulation; Near-infrared light; Red blood cells