Ischemia-Reperfusion Injury in the Vascular Surgery Patient: Fundamental Concepts
Ischemia–reperfusion injury (IRI) is the sine qua non of organ failure in vascular surgery patients, and the techniques inherent to vascular surgery create a highly specific milieu that promotes multiorgan ischemia–reperfusion.
IRI, particularly in vascular surgery patients, is a highly complex micro- and macrophysiologic process; this helps explain why single interventions aimed at single components of this process (e.g., increasing blood pressure to maximize flow) have proven ineffective in clinical studies.
Prevention of Kidney Injury. Perioperative acute kidney injury (AKI) is a common complication of vascular surgery and is associated with high morbidity and mortality (incidence of AKI is between 16% and 22% of patients undergoing aortic surgery). Preoperative renal dysfunction is the most powerful predictor of postoperative renal dysfunction.
Pharmacologic Approaches. There is currently no clinical evidence to support the benefit of any pharmacologic intervention or protection strategy (mannitol, loop diuretics, dopamine).
Nonpharmacologic Approaches. Multiple nonpharmacologic strategies have been used to prevent renal injury during aortic surgery. It was hoped that morbidity and mortality from endovascular aneurysm repair (EVAR) would be reduced compared with open aortic aneurysm repair. (Trials found no long-term difference in renal function between open repair and EVAR.)
Prevention of Pulmonary Complications. Pulmonary complications (pneumonia, respiratory failure) are common after major vascular surgery (10%–30% of AAA patients) and are associated with increased mortality and length of stay. Postoperative lung expansion with continuous positive airway pressure or incentive spirometry and postoperative thoracic epidural analgesia reduce perioperative respiratory complications.