Implanted date: device was not implanted.Explanted date: device was not explanted.Occupation- clinical engineer.The actual sample was received for evaluation visual inspection of the oxygenator revealed no breakage or other anomalies in the appearance.The oxygenator was rinsed with normal saline flowed by head, and then the oxygenation module was inspected visually.Formation of blood clots was observed.The blood clots seemed to have formed along the blood flow.The oxygenator was fixed by being filled with glutaraldehyde-containing normal saline, and then the housing and the filter were removed.Visual inspection of the oxygenation module found formation of blood clots.The oxygenation module was visually inspected while the fiber layer was removed gradually.Formation of blood clots was observed over the entire circumference.No anomaly was noted in the winding state of fiber.The heat exchanger was removed from the outer cylinder and subjected to visual and magnifying inspections.Formation of blood clots was observed.The filter and the fiber were inspected under an electron microscope.Adhesion of blood cell components including red blood cells and formation of fibrin net were observed.Visual inspection of the reservoir revealed a formation of blood clots in the bottom part of the reservoir and in the cardiotomy (cr) filter.The reservoir was disassembled, and both surfaces of the venous filter and the defoamer inside the venous filter after submerged in normal saline were inspected visually.Formation of blood clots were observed including the inside.Both surfaces of the cr filter and the defoamer inside the cr filter after soaked in normal saline were inspected visually.Formation of blood clots were observed inside.The blood clots collected from the reservoir were subjected to electron microscopic inspection and found to be aggregated blood cell components such as red blood cells.A review of the device history record and product-release judgement record of the involved product code/lot# combination was conducted with no findings.Ifu states: do not reduce heparin during circulation.Otherwise, blood clotting might occur.Adequate heparinization of the blood is required to prevent it from clotting in the system.Based on the provided information and investigation results, there is no definitive evidence that this event was related to a device defect or malfunction.From the results of the investigation, the formation of blood clots was observed over the filter, fiber, and heat exchanger of the oxygenator.Electron microscopic inspection found adhesion of blood cell components including red blood cells and formation of fibrin net.As for the reservoir, the formation of many blood clots was observed inside the venous filter and cr filter.Electron microscopic inspection of the blood clots found aggregated blood cell components including red blood cells.As a cause of the formation of blood clots, based on the description of the event that no increasing pressure was observed before the oxygenator during the operation and the blood clots inside the oxygenator seemed to have been formed along the flow of blood, it was likely that the blood clots may have formed gradually after the protamine was administered during weaning process.However, the exact cause of the reported event cannot be definitively determined based on the available information.(b)(4).
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