Development of a Method for Visualizing and Quantifying Thrombus Formation in Extracorporeal Membrane Oxygenators
Extracorporeal Membrane Oxygenation (ECMO) is a life-support technology used for patients with cardiac and respiratory failure. Although ECMO plays a crucial role in clinical practice, its use is accompanied by significant risks of medical device-associated thrombosis. Thrombosis not only obstructs blood flow in the oxygenator but also reduces gas exchange efficiency, potentially leading to severe complications such as pulmonary embolism and ischemic stroke in patients. Currently, systemic anticoagulants (e.g., heparin) are primarily used in clinical practice to reduce thrombosis risks. However, anticoagulation therapy itself carries risks such as bleeding and heparin-induced thrombocytopenia. Therefore, research on reducing thrombosis in ECMO oxygenators and developing more effective antithrombotic strategies is of great clinical significance.
In this context, Jenny S. H. Wang and her team conducted a study aimed at developing a method for visualizing and quantitatively analyzing thrombosis in ECMO oxygenators. This method allows researchers to gain deeper insights into the distribution patterns of thrombosis in oxygenators and provides a scientific basis for evaluating new biomaterials or pharmacological antithrombotic strategies.
Source of the Paper
The study was conducted by scholars from multiple institutions, including Oregon Health & Science University and Johns Hopkins University. The research team included Jenny S. H. Wang, Amelia A. Rodolf, Caleb H. Moon, and other researchers. The paper was published in 2025 in the journal Cellular and Molecular Bioengineering, titled Development of a Method for Visualizing and Quantifying Thrombus Formation in Extracorporeal Membrane Oxygenators.
Research Process
1. Patient Recruitment and Oxygenator Collection
The study first recruited patients aged 18 and above receiving ECMO treatment and collected their used oxygenators. Patients expected to be on ECMO for less than 24 hours, as well as those diagnosed with hemophilia or congenital factor XII deficiency, were excluded. Ultimately, the study included 18 oxygenators from 17 patients (13 square oxygenators and 5 circular oxygenators). After removal from patients, the oxygenators were immediately rinsed with saline to prevent further thrombosis.
2. Oxygenator Processing and Fixation
The collected oxygenators were fixed in a 4% paraformaldehyde solution to maintain structural integrity. Researchers then used a stainless-steel bandsaw to cut away the outer casing and removed internal components such as metal springs to prevent artifacts during subsequent imaging. For circular oxygenators, they were cut along the vertical axis into two halves to accommodate the dimensions of the microCT system.
3. MicroCT Imaging and Image Reconstruction
Oxygenators were immersed in Lugol solution before imaging to enhance the contrast of thrombi. Researchers used the Siemens Inveon microCT system to image the oxygenators, obtaining a three-dimensional stack of 1,024 images. The resolution was 98.731 micrometers, with imaging parameters of 80 kV voltage and 114 µA current.
4. Thrombus Quantification
Dragonfly software was used for image reconstruction and segmentation. Researchers quantified thrombus volume in different regions of the oxygenators through density mapping. For square oxygenators, they were divided into five structurally distinct layers, and three randomly selected slices from each layer were analyzed for thrombus area. For circular oxygenators, due to their uniform structure, only three-dimensional quantification was performed.
5. Scanning Electron Microscopy (SEM) and Histological Staining
To further analyze thrombus composition, researchers extracted thrombus samples from the oxygenators and observed them using SEM and H&E staining. SEM images revealed the distribution of red blood cells, platelets, and fibrin in the thrombi, while H&E staining was used for qualitative analysis of thrombus composition.
Key Findings
1. Spatial Distribution of Thrombi
The results showed that the second layer of square oxygenators (the second layer in the direction of blood flow) had the largest thrombus area, indicating that this region is more prone to thrombosis. In circular oxygenators, thrombi were primarily concentrated in the blood inflow region and spread outward due to centrifugal force.
2. Three-Dimensional Quantification of Thrombi
Through three-dimensional density mapping, researchers calculated the percentage of thrombus volume in the oxygenators. The results showed that thrombus volume significantly increased with prolonged ECMO use. No thrombi were detected in unused oxygenators.
3. Thrombus Composition Analysis
SEM and H&E staining results showed that thrombi in the first layer of square oxygenators were primarily composed of red blood cells, while the second layer was rich in fibrin. Thrombi in circular oxygenators exhibited a tight mixture of red blood cells and fibrin.
Research Conclusions
The study successfully developed a method for visualizing and quantitatively analyzing thrombosis in ECMO oxygenators. This method allows researchers to precisely quantify the distribution and volume of thrombi in oxygenators, providing an important tool for evaluating new antithrombotic strategies. Additionally, the study revealed the impact of oxygenator structure on thrombosis, offering a scientific basis for future improvements in oxygenator design.
Research Highlights
- Methodological Innovation: This study is the first to apply microCT technology to thrombosis analysis in ECMO oxygenators, providing a high-resolution three-dimensional visualization method.
- Clinical Significance: By quantifying thrombosis, this method can help clinicians better assess thrombosis risks during ECMO treatment and optimize anticoagulation therapy.
- Scientific Value: The study highlights the influence of oxygenator structure on thrombosis, providing important references for developing safer ECMO devices.
Other Valuable Information
The study also found that thrombosis occurs rapidly in the early stages of ECMO treatment, and thrombus composition varies significantly across different regions. These findings offer new directions for further research into the mechanisms of thrombosis.
Summary
The research by Jenny S. H. Wang and her team provides an important tool for visualizing and quantitatively analyzing thrombosis in ECMO oxygenators. This method not only holds significant clinical application value but also offers a scientific basis for future improvements in ECMO device design. Through further research, this method is expected to play a crucial role in reducing ECMO-associated thrombotic complications.