Anesthetic Management of Vascular Emergencies

Despite the increasing number of elective abdominal aneurysmectomies, rupture of abdominal aortic aneurysms still occurs. In 1950, Estes ~ reported that when no surgical resection was performed, ruptured aneurysms accounted for 63.3% of the deaths occurring at 5 years from the time of diagnosis of the aneurysm. In another report, 2 in cases in which the aneurysm was not resected, 35% of all deaths at 5 years were due to ruptured aneurysm. In another series of 52 patients who did not undergo aneurysm resection, Darling et al 3 reported that 43% of deaths at 1 year were due to rupture. Although aneurysms over 10 cm in diameter tend to rupture six times more frequently than smaller aneurysms ( < 4 cm in diameter), 4 the size of the aneurysm should not be the major factor in selection of patients for surgery. 5 The incidence of ruptured aneurysms in different surgical series varies, depending on how aggressive the surgeons are and their policy of aneurysm resection. It is reported that 4% to 37% of ruptured aneurysms are atherosclerotic. 6"~3 Aortic rupture may also occur at the point of origin of dissection of the aorta, which is the site of the mural tear. 14'15 Another rare type of ruptured aneurysm is a mycotic aneurysm. and shock are extremely common, some patients may exhibit normal blood pressure. The absence of hypotension is misleading, and is a common reason for the failure to diagnose a ruptured aneurysm. 6'9'10'16 Abdominal aneurysms may rupture retroperitoneally; in this situation, the patient may not demonstrate symptoms of shock because of temporary tamponade of the bleeding site. This occurs in 75% of patients with ruptured aneurysms. 4 Rupture into the peritoneal cavity usually is accompanied by severe hypotension and exsanguination occurs rapidly. Reports have shown that this occurs in approximately 25% of patients with ruptured abdominal aneurysms. 3'6'7'12'16'17 Rupture may also occur into other organs or sites, and when the rupture occurs into the inferior vena cava, it may produce an arteriovenous fistula. 17 The diagnostic triad of a pulsatile abdominal mass, back pain, and shock may not be present in all patients with ruptured aneurysms. Donaldson et al Is reported that this triad exists in less than 50% of such patients. If the diagnosis is in doubt and the patient's hemodynamic status is stable, other tests and an emergency computed tomography scan should be performed. If the patient is hemodynamically unstable and the diagnosis of a ruptured aneurysm is suspected after clinical evaluation, surgery should be performed immediately. Other tests are then considered a waste of valuable time during which deterioration of vital signs may occur.