Systemic lupus erythematosis (SLE) is an autoimmune disease frequently accompanied by the presence of an antiphospholipid antibody (APA). Early referred to as the lupus anticoagulant (LAC), this APA consists of immunoglobulins that are known to interfere with coagulation tests that are phospholipid dependent. Such tests include the partial thromboplastin time (PTT), the activated clotting time (ACT) and may affect the thrombin time (TT). This challenges the cardiac surgical team and the perfusionist responsible for monitoring anticoagulation while performing cardiopulmonary bypass (CPB). A 46-year-old female with a history of SLE, severe mitral insufficiency, an anterior wall myocardial infarction, and the presence of a LAC was admitted for mitral valve surgery. Replacement of the mitral valve was accomplished successfully, utilizing CPB. Anticoagulation was managed using the Hepcon HMS PLUS, a device that calculates an individual's heparin dose response and permits assessment of the heparin concentration throughout the procedure. The patient recovered and was sent home 16 days after surgery.
A new pneumatic artificial heart system has been developed. The design criteria have been to produce an integrated series of blood pumps and drive systems that would reduce blood trauma and reactivity, while incorporating industrial, mass-production techniques. The system attempts to reproduce the natural heart's pressure and flow waveforms and allows the prosthetic valves to be installed in a manner consistent with their design. The system's ventricles are constructed entirely of polyurethane by a combination of vacuum-forming and solution-casting techniques. The atrial cuffs and arterial grafts are permanently attached to the pumps and do not incorporate a quick connect system. The prosthetic valves are sewn into the inflow and outflow tracts using their clinical sewing rings. Besides eliminating the crevices normally found in quick connect systems, this method mounts the valves in an extremely compliant housing to increase shock absorption. The drive system produces a systolic air flow with a variable pressure rise (dP/dt) to reduce mitral valve closing velocity. This system has been implanted into 25 calves to date, of which 17 were chronic experiments. In 14 animals, St. Jude bileaflet valves were used and these animals had a mean survival of 39 days. Six of these animals survived over 30 days, with the longest being 129 days. All of the animals showed the characteristic postoperative drop in red blood cell count and hematocrit that returned to near preoperative values in about 3 weeks. The plasma free hemoglobin values generally remained below 5 mg/dl. The necropsies performed on several of the earlier animals revealed renal infarcts. However, in two of the later experiments, no kidney damage was found. The blood contacting surfaces of the atrial cuffs from the animals surviving over 100 days were covered with a fibroproliferative pseudoneointimal growth that extended from the sewing rings to the natural atrial tissue. Grossly, this appears to be the same type of tissue response seen when only a valve is implanted in a natural calf heart.
Clinical staff perfusionists are responsible for training perfusion students to perform tasks and manage patients in the clinical setting. They are often the least prepared to assume this teaching role. To address this need, a modular programme has been developed to provide the teaching staff with instructional skills. Adult learning theory specifies that an effective learning environment addresses issues of saliency, motivation, retention and transfer. Adults have different expectations, so this programme is designed to maximize this process. The programme is comprehensive and may be used for didactic instruction as well. Derived from a model designed for physicians as teachers, five modules provide theoretical support for teaching techniques, learning tools and management techniques for giving feedback and evaluating performance. Specifically, the topics address the following subjects: managing and motivating learners; teaching medical problem solving; teaching clinical skills; giving feedback and evaluating performance. The short curriculum is based on teaching principles that apply to adult learners with diverse learning styles. While presenting techniques to use with different types of learners, the programme itself incorporates these techniques in teaching the teachers. The modules use lectures, demonstrations, role playing and video taping to challenge teachers and learners in the cognitive, psychomotor and affective domains. The success of this programme is its ability to engage each participant in the learning process.
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