Clinical study of the cerebral hemodynamics during extracorporeal circulation.

The cerebral circulation was studied on 40 clinical cases which underwent open heart surgery under extracorporeal circulation by the low flow rate-hypothermic-hemodilution technique, by means of Kr85, opthalmoscope, blood gas and pH, and cerebral metabolism. Cerebral blood flow decreased to 65.2 per cent of the control value after the start of extracorporeal bypass, but recovered by the later period of total perfusion, and then exceeded the control value during the rewarming and partial perfusion. Cerebral metabolism was lowered to 37 per cent of the control ''alue during the total perfusion, but recovered during the rewarming perfusion. It was pointed out that the findings of the retina were useful to assess the adequacy of the cerebral hemodynamics during the bypass. The present technique of extracorporeal circulation in this department of surgery was concluded to be adequate for the cerebral circulation.