The role of permissive hypotension in the management of ruptured abdominal aortic aneurysms.

The aim of this review was to explore current literature pertaining to the use of permissive hypotension in the treatment of abdominal aortic aneurysms. A literature search using Metalib, a database search engine, provided at the Royal Free and University College of London (UCL) yielded articles using the keywords "permissive hypotension" and "hypotensive resuscitation" when linked to "abdominal aortic aneurysm" and "rupture". The articles studying permissive hypotension in animals and humans in trauma, and in patients with abdominal aortic aneurysm were reviewed. The result of this search was a large volume of experimental studies of trauma in animals giving satisfactory evidence of the physiological benefit of this concept of resuscitation in trauma. There were some randomized trials in humans in trauma suggesting benefit. The safety of permissive hypotension in patients with ruptured aortic aneurysms was documented and found to be widespread, but there were no randomized trials directly comparing this practice. Evidence from a prospective randomized study on the modality of treatment of ruptured aortic aneurysms suggest that the level of blood pressure is associated with the mortality and a prospective cohort study suggests that, using the complementary concept of "delayed volume resuscitation", the total volume of preoperative fluid resuscitation independent of the blood pressure is predictive of the risk of perioperative death in ruptured aortic aneurysms. To this end, recent clinical publications are now supportive of control of both the volume of preoperative fluid given and blood pressure in this group of patients but clinical studies are few.