33, 31, 32, 37, 42
The pump is not only a place where clot forms but the place clot ARRIVES: a thrombus that grew in the venous limb or at a connector can break off and land in the head, where it is ground rather than passed to the patient. That reframes a rising plasma free haemoglobin — it may be reporting a clot nowhere near the pump. A RAPIDLY rising transmembrane pressure drop over 1 to 2 days points specifically at inflow membrane surface thrombus, which distinguishes it from the slower climb of diffuse fibre deposition. And the antifibrinolytic signal sits beside Chapter 31's finding that 2 of 4 patients given activated factor VII developed acute oxygenator thrombosis, and the protamine hazard: three prohaemostatic interventions, three circuit-thrombosis signals, none quantified. Finally, this series is the demonstration of what Chapter 31 section 31.8 asks for — examining the explanted circuit produces data that exist nowhere else.
Not applicable; descriptive with within-series associations
DOI 10.1097/MAT.0000000000001605; PMID 34860711
Systematic post-removal examination of the complete circuit — the examination Chapter 31 section 31.8 asks programmes to perform routinely
ABSTRACT READ ONLY; full text not retrieved. Forty-six patients, all paediatric, single centre. Proportions are of circuits examined rather than of patients supported, so they are not incidence figures. No exposure denominators are given for the antifibrinolytic association, which is therefore hypothesis-generating only. No adult equivalent series was retrieved.
THROMBI WERE FOUND IN 81 PERCENT OF CIRCUITS. By site, as proportions of circuits: pump axle thrombi with fragments trapped in the oxygenator 45 percent (classed by the authors among the LESS clinically significant); arterial tubing 30 percent; venous tubing 26 percent; connectors 26 percent; deep oxygenator membrane 15 percent; INFLOW OXYGENATOR MEMBRANE SURFACE 11 percent. The most clinically significant were the inflow oxygenator membrane surface thrombi, the arterial tubing thrombi, and the venous tubing and connector thrombi. INFLOW SURFACE THROMBI PRODUCED A RAPIDLY INCREASING PRESSURE DROP ACROSS THE OXYGENATOR OVER 1 TO 2 DAYS, OXYGENATOR FAILURE AND CIRCUIT REPLACEMENT, and were associated with intravascular venous thrombosis and bacterial infection present before ECMO began. IN 11 PERCENT OF CASES A VENOUS TUBING THROMBUS GREW LARGE ENOUGH TO BREAK OFF AND EMBOLISE TO THE PUMP, RESULTING IN INCREASED HAEMOLYSIS. In one case an arterial cannula or tubing thrombus led to aortic and mesenteric artery thrombosis followed by bowel infarction. SAFETY SIGNAL: antifibrinolytic therapy during ECMO was associated with an increased risk of pump thromboembolism. The authors conclude that examining circuits after removal is a useful quality-improvement tool that can elucidate the cause of circuit problems, identify patients at increased thrombotic risk, and suggest areas for improvement.
53 explanted ECMO circuits from 46 paediatric patients, single centre. Tubing, pump and oxygenator examined for visible thrombi, with representative samples taken for histological, immunofluorescence and immunohistochemical analysis.