Abstract： Objective To investigate the cerebral protective effects of hyperoxia management during deep hypothermia circulatory arrest（DHCA） rabbit by the blood gas indexes, superoxide dismutase（ SOD） activity and malondialdehyde （MDA） levels of brain, and ratio of water to brain. Methods A DHCA and antegrade selective cerebral perfusion （ASCP） rabbit model was established. Twenty-four 11-13 week-old male New Zealand rabbits（ weighing 2.7 to 3.4 kg） were assigned to three groups with a random number table: a sham operation group （Sham group）, an ASCP group （S group）, and an ASCP ＋ hyperoxia management group （SH group）. There were eight rabbits in each group. We recorded the intraoperative values for arterial oxygen pressure （PaO2）, arterial oxygen saturation （SaO2）, jugular venous oxygen pressure（PjvO2）, jugular venous oxygen saturation（ SjvO2） and blood lactate level. The brain SOD activity, MDA levels, and ratio of water to brain were measured after the operation. Results Before initiating circulatory arrest, before initiating reperfusion and five minutes of reperfusion, levels of PaO2 , PjvO2 , and SjvO2 in the SH group were significantly higher than those of the S group and Sham group. SOD activity in the SH group was not significantly different from that of the S group[（213.53±33.52） U/mg. prot vs. （193.02±27.67） U/mg. prot] and Sham group[（213.53±33.52） U/mg. prot vs.（244.38±35.02）U/mg. prot], but the SOD activity in the S group was lower than that in the Sham group（ P ＜ 0.05）. MDA levels in the SH group were lower than that in the S group[（1.42±0.30） nmol/mg. prot vs. （2.37±0.55） nmol/mg. prot, P ＜ 0.05]. Conclusion Our data show that hyperoxia management during DHCA＋ASCP improves rabbits’PjvO2 and SjvO2, maintains brain SOD activity, and decreases brain MDA levels, demonstrating the neuroprotective effects of hyperoxia mangagement.
Objective To compare the outcome of patients with the strategy of conventional and steady cooling ＆ rewarming and cold reperfusion , who suffered from DeBakey type Ⅰ aortic dissection or aortic arch aneurysm and underwent the total aortic arch replacement. Methods Thirty-two patients who underwent total arch replacement were randomly allocated to one of two strategies of temperature management in cardiopulmonary bypass （CPB）, conventional group （group C, 16 cases） and steady cooling ＆. rewarming and cold reperfusion group （group S, 16 cases）. The jugular bulb venous oxygenation saturation （SjvO2）, jugular bulb venous oxygen tension （PivO2） and jugular bulb venous blood temperature （JVBT） were tested or monitored during the operation. Preoperative and postoperative neurological examinations and brain computerized tomography scan were performed. Results All patients survived the operations and were discharged from hospital. No new brain infarction occurred. Transient neurologic dysfunction occurred in 2 patients of the group S and 3 patients of the groupC. The “cooling ＆ rewarming blanket-impress puple” occurred in 4 cases of the group C. The SjvO2, PjvO2, lowest nasopharyngeal temperature and the post operative nasopharyngeal temperature of the patients in group S were significantly higher than those of the patients in group C （SjvO2 0.85±0. 11 vs. 0. 74±0.23, PjvO2 36. 9± 15.6mmHg vs. 24.5±7.7mmHg, P（ 0.01 ）. While the highest brain temperature, wake time and ICU stay in group S were remarkably lower than those in group C （P 〈0. 01,0. 05）. Conclusion With less postbypass afterdrop and satisfactory clinical outcome, the strategy of steady cooling ＆ rewarming and cold reperfusion can effectively avoid brain hyperthermia and mismatch of cerebral blood flow metabolism in the surgery of total aortic arch replacement.