Protective effect of continuous retrograde cerebral perfusion on the brain during deep hypothermic systemic circulatory arrest.

Deep hypothermic circulatory arrest has been widely used as an adjunct for surgery of the aortic arch to protect the brain and other vital organs. We introduced the use of continuous retrograde cerebral perfusion via the superior vena cava during deep hypothermic circulatory arrest in 1987 and have used it in 33 patients. Continuous retrograde cerebral perfusion times ranged from 10 to 89 minutes (mean 40.2 +/- 22.5), and minimal nasopharyngeal temperatures ranged from 14 to 25 degrees C (mean 17.4 +/- 2.0). Two patients with a ruptured aneurysm died during operation due to bleeding and two other patients, with continuous retrograde cerebral perfusion time of 24 and 35 minutes, died 1 month postoperatively due to preoperative liver cirrhosis and sepsis. Two patients suffered from stroke. The remaining 27 patients, including 6 with from 60 to 82 minutes of continuous retrograde cerebral perfusion, had no complications related to continuous retrograde perfusion. During continuous retrograde cerebral perfusion, 66 pairs of blood samples from the perfusate and from the drainage back to the arch vessels were obtained. Analysis of these samples revealed that partial pressure of oxygen, saturation of oxygen, and oxygen content significantly decreased (p < 0.001), and partial pressure of carbon dioxide (CO2) and CO2 content significantly increased (p < 0.001). The nasopharyngeal temperature gradually increased at the rate of 0.01 to 0.03 degree C/min, but was maintained below 20 degrees C. These results reflect the fact that the aerobic metabolism of the brain is maintained during continuous retrograde cerebral perfusion due to oxygen and substrate availability. This technique offers the potential of metabolic support to the brain during deep hypothermic circulatory arrest and prolongs the safe time limits of deep hypothermic circulatory arrest in surgery of the aortic arch.