Leave No Clot Behind: The Role of Retained Clot in Post Operative Effusions After Cardiac Surgery

Drainage systems are used to evacuate blood from around the heart and lungs after cardiac surgery. If the drainage capacity exceeds the amount of bleeding, then the blood is fully evacuated. When the drainage capacity is impaired, for example by obstruction from chest tube clots, then blood is retained around the heart (pericardial space) and lungs (pleural spaces). Blood that is retained in these spaces cause a host of complications called Retained Blood Syndrome (RBS), often impairing patient recovery.

Leave-No-Clot1Blood that pools turns to clot. What is the fate of these clots in the pleural and pericardial spaces? It depends on the volume and location. Large volume clots must be surgically evacuated in a re-exploration procedure in the early days after surgery. Smaller, more focal clots that compress the heart can lead to hemodynamic compromise (pericardial tamponade) that can threaten the patient’s life. These can require a subsequent drainage procedure as well.

What about smaller clot collections that are not clinically recognized in the early days after surgery? A number of studies chronicle the reabsorption process of blood in the pleural and pericardial spaces after surgery and suggest that there is an initial breakdown period where the clot contracts and the more solid elements are separated from the fluid elements. This results in a bloody fluid production that is recognizable clinically as pericardial or pleural effusions, and is seen in between 60% and 80% of patients after heart surgery.1, 2  Between 10% and 15% of these patients required a pleural drainage procedure during recovery after cardiac surgery.1, 2, 3 When this fluid is examined under the microscope, there are bloody elements as well as inflammatory elements, a finding that correlates with experimental studies that show the pleural or pericardial surfaces remain inflamed throughout the acute, subacute, and chronic phases.3 This is no surprise as the thrombin contained in the clot is highly pro-inflammatory.4 This sets up a situation where fluid production, driven in part by vascular endothelial growth factor (VEGF), can continue as the inflammation flares initially, and then simmers before it goes away.5,6

There is a growing appreciation that this may impact the high number of patients who have slow recoveries and even require subsequent fluid drainage procedures and/or readmission after heart surgery. Currently, nearly 1 in 5 cardiac surgery patients are readmitted within 30 days of discharge,7 and approximately 20% of readmissions are caused by pleural or pericardial effusions.8

How can this be minimized? For starters, maximizing early drainage capacity by keeping chest tubes clear has been shown to reduce RBS experimentally, and studies are ongoing to correlate these findings in the clinical setting.9 Studies have shown that ACT with PleuraFlow reduces bloody pleural and pericardial effusion clinically in patients recovering from heart surgery. In the United States, PleuraFlow is the only regulatory cleared product labeled to reduce effusions associated with retained blood. Ultimately, becoming more aggressive about “leaving no clot behind” appears to be a strategy that may reduce these complications that impact hospital outcomes and increase long term costs of recovery.

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