The survivors had slightly higher mean arterial pressure, cardiac index, and mixed venous oxygen saturation, as well as significantly higher oxygen delivery, oxygen consumption, transcutaneous oxygen tension, and transcutaneous oxygen tension/FIO2 ratios, than did the nonsurvivors. The data suggest that blood flow, oxygen delivery, and tissue oxygenation of the nonsurvivors became inadequate toward the end of the operation. Noninvasive monitoring provides similar information to that of the PAC; both approaches revealed low-flow and poor tissue perfusion that were worse in the nonsurvivors. The continuous on-line real-time displays of hemodynamic trends facilitate early recognition of acute circulatory dysfunction.
Although endovascular surgery for aortic aneurysms can be traced to the 19th century, open surgery has dominated during the past 50 years. Indeed, open repair of aneurysms has been one of the most successful developments in vascular surgery. Despite improvements in mortality rates, open repair remains a major operation often undertaken in patients with significant comorbidities. Starting from basic research dating back several decades, the 1990s were noted for very active clinical development of endovascular abdominal aortic repair in an attempt to provide an alternative to open repair, especially for high-risk patients. Early successes with decreased intensive care unit and hospital stays were tempered by technical issues and the "endoleak," the term given to an incomplete exclusion of the aneurysm from the circulation. This potential for rupture, despite treatment, was cause for concern. The need for long-term surveillance and secondary procedures, if not conversion to open repair, further compounded these issues. Despite these concerns, progress continued, and by the end of 2002, the Food and Drug Administration had approved three devices for marketing. Although surgeons are faced with increasingly complex issues related to endovascular repair, anesthesiologists have found their management of this procedure to be simpler in many ways. The smaller incisions and improved hemodynamic stability have led to a variety of anesthetics being tried, including monitored anesthesia care. Anesthesiologists continue to explore a number of opportunities to improve patient outcome in these procedures. These include selection of the most optimal anesthetic, the most appropriate perioperative renal protection, and the best preparation for and management of a conversion to an open procedure. Whatever the final role for endovascular surgery in the management of abdominal aortic aneurysms, it is an intellectually stimulating and scientifically promising technique for surgeons, anesthesiologists, and the patients they serve.A lthough it is common to trace endovascular A aortic surgery to the clinical trials of the 1990s, which were based on experimental work dating from 1969,1,2 endovascular techniques can
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