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| Literature Review |
by Alan P. Kypson, MD
East Carolina University, Greenville, NC, United States |
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Clinical Experience with the Mini-Extracorporeal Circulation System: An Evolution or a Revolution?
Remadi, et al., have recently submitted (Ann Thorac Surg 2004;77:2172-2175) an informative review of their clinical experience with a mini-CPB or mini-extracorporeal circulation (MECC) system (Jostra AG, Hirrlingen, Germany) in 150 patients.
The MECC circuit utilized is a fully heparinized, closed-loop system. Tubing length is less that 100 cm. It uses a high performance hollow fiber oxygenator and has two vent ports that prevent passage of microbubbles through the circuit to the patient. It utilizes a centrifugal pump whose flow capacity is greater than 9L/min. The flow capacity is directly related to the blood volume of the patient, which must be carefully monitored by the surgical team. Total priming volume is 450 mL. It has the capability to use a suction system, allowing a vent to be placed into the ascending aorta (for CABG) or into the pulmonary artery (for AVR).
Over the course of a year and a half, 150 patients underwent CABG (n= 105), CABG/AVR (n= 11)or AVR (n= 34) using the MECC system. Cannulation was comparable to conventional CPB. Myocardial protection consisted of high potassium warm cardioplegia solution. The mean hematocrit decreased for the entire group by 2.4%. The prevalence of intraoperative blood transfusion was 6%. The 30-day operative mortality was 1.3%. One patient experienced renal failure requiring hemodialysis, and one patient suffered postoperative neurologic dysfunction. On three occasions, air entered the venous inflow, resulting in bubbles that were noted in the oxygenator. This air never passed through to the oxygenator outflow and apparently never caused any harm. There was no mention of whether the patient with postoperative neurologic dysfunction was one of these patients.
In summary, this study demonstrated that postoperative mortality and morbidity were low in this group. The hematocrit was quite stable postoperatively, resulting in a relatively low rate of transfusion. Because the patient is the venous reservoir for the system, tight control of the vascular tone by the anesthesiologist and perfusionist is paramount. Clearly, this novel technology has a learning curve. Nevertheless, potential advantages over standard CPB warrant further evaluation by the surgical community.
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