Effect of Intraoperative Aprotinin Administration on Post Cardiac Surgery Optic Nerve and Retinal Thickness.

Cognitive and neurological dysfunction after coronary artery bypass surgery (CABG) is common and multi-factorial in origin. Causative factors include cerebral Embolization (1), cerebral ischemia reperfusion (2), cerebral hyperthermia after discontinuation of cardiopulmonary bypass (CPB) (3), and the systemic inflammatory response to CPB (4). Cognitive dysfunction is reported in 53% of patients at discharge from the hospital, 36% at six weeks and 42% at five years (5). Cognitive function at discharge from hospital is a predictor of long-term cognitive outcome (5). Adverse neurological outcome has been classified as: type I (focal neurological injury, stupor or coma) and type II (deterioration in intellectual function, memory deficit or seizures). Patients with adverse cerebral outcomes have greater in-hospital mortality, longer hospitalization and a greater rate of discharge to facilities for intermediate or long-term care (6). Adverse neurological outcome after otherwise successful surgery is devastating for the patient, their family and society.

Neurocognitive testing is the most established method to assess post cardiac surgery cognitive outcome. Despite the extensive use of neurocognitive testing procedures in the research literature, there is uncertainty regarding the precise interpretation of findings in any given study. Thus, new tools to evaluate cognitive outcome are now being investigated.

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. Two aprotinin dosing regimens are used for prophylactic reduction of perioperative blood loss and the need for blood transfusion in patients undergoing cardiopulmonary bypass (CPB). Serum concentrations achieved with the full-dose regimen inhibit both kallikrein and plasmin activity resulting in attenuation of the systemic inflammatory response to bypass, whereas serum concentrations achieved with the half-dose regimen only inhibit plasmin activity.

In-spite of the fact that aprotinin has been administered for more than a decade to cardiac surgery patients, it's safety is still controversial. Several studies have reported an increase risk for postoperative MI, CVA and renal failure after it's usage. Thus, its usage is not a standard of care, and depends on the surgeon decision (13).

Evidence supporting the neuroprotective effects of aprotinin given during surgery was obtained in several studies.