[The protective effect of continuous retrograde cerebral perfusion on the central nervous system during deep hypothermic systemic circulatory arrest]

Deep hypothermic circulatory arrest (DHCA) was introduced as an adjunct for operations involving aortic arch lesions in 1970's and has since been widely used. Profound hypothermia protects the brain and other vital organs by reducing metabolic rate. We initiated the use of continuous retrograde cerebral perfusion (CRCP) via the superior vena cava during DHCA in 1987. We studied 15 patients who required DHCA and CRCP during repair or replacement of the aortic arch. CRCP times ranged from 11 to 78 (mean +/- S.D.; 37.3 +/- 21) minutes, and minimal nasopharyngeal temperatures ranged from 13.7 to 25 (17.7 +/- 2.6) degrees C. Two patients died one month postoperatively due to preoperative disease. Three patients, who were in shock preoperatively due to cardiac tamponade, developed acute renal failure postoperatively. The remaining patients were weaned from the respirator by the 2nd postoperative day. No patient had CRCP-related complications. During CRCP, the partial pressure of oxygen (PO2), saturation of oxygen (SO2), and oxygen content significantly decreased (p0.001), and the partial pressure of carbon dioxide (PCO2) and CO2 content significantly increased (p0.001) between retrogradely perfused blood and blood draining from the arch vessels. These results most probably reflected that the aerobic metabolism of the brain was maintained by CRCP while the central nervous system was maintained in a hypothermic state, with oxygen and substrate availability, wash-out of metabolites, and buffering capacity and oncotic pressure of the blood maintained. This technique offers the potentials of sufficient metabolic support to the brain during DHCA and prolonged safe time limits of DHCA.