To look at literature and explore our own experiences surrounding high pressure excursions, to highlight causes and high risk patients and determine a strategy for management and prevention. Finally to consider a link between reported increase in HPEs and the Covid 19 pandemic
Literature review Case study review Multi centre survey
Results / Discussions
HPE are the most commonly recorded adverse events involving membrane oxygenators. The phenomenon usually occurs upon initiation of CPB displaying as high pre membrane pressures, increasing trans membrane pressure drop and poor gas exchange. Common findings demonstrate a fibrin gel network with platelet activation which binds to the oxygenator fibres and heat exchanger. This significantly reduces the blood flow pathway leading to high membrane pressures and increases the distance for diffusive gas exchange leading to poor oxygenation.
There have been a number of documented common causes including patients with high platelet / fibrinogen levels, those who were previous smokers, and patients displaying heparin resistance. These incidents are most commonly occurring in patients undergoing CABG for coronary artery disease but most recently there seems to have been an increase potentially due to the COVID 19 virus.
Making practitioners aware of these highly stressful occurrences can only benefit clinical practice. Following a clear protocol to try and alleviate the HPE can reduce the number of potentially unnecessary oxygenator change outs and ultimately reduce patient risk.