Effect On Cerebral Blood Flow During Endoscopic Neck Surgery With Carbon Dixide Insufflation In Rabbits Model

Objective: (1) To study the effect and the significance on cerebral blood flow by analyzed cerebral oxygenation during endoscopic neck surgery with carbon dixide insufflation in rabbits model. (2) To study the effect on Endothelin(ET) and Neuron nitricoxide synthase(nNOS) in brain tissue during endoscopic neck surgery with carbon dixide insufflation and to investigate the possible roles of brain damage in rabbits model.Methods: Twenty-four rabbits, 6 per group, underwent endoscopic neck surgery .Insufflation was performed with CO₂ at OmmHg(sham), 4mmHg, 8 mmHg, 12 mmHg. Mean artery pressure(MVP), Heart rate(HR), central venous pressure(CVP) dynamically monitored during insufflation. The change in PjvO₂ (oxygen pressure of jugular blood), SjvO₂ (oxygen saturation of jugular blood), Ca-jvDO₂ (cerebral ateriovenous difference of oxygen) were observed. After 150 min, we use immunohisto-chemicalacid to dyeing ET and nNOS of rabbit cerebral tissue and use computer image analysis system to assess their expression.Results: (1) After 150 min mean CVP increased significantly with CO2 at 12 mmHg to 7.54±0.23cmH2O (P<0.05), mean MAP without significant changes. Mean PJVO2 and mean SJVO2 of the 8 mmHg group, the 12 mmHg group was greatly decreased compared with the sham group and the 4mmHg group at 150 min (P<0.05). meanCa-jvDO₂ of the CO2 insufflation groups improved obviously (P<0.05) compared with the sham group. (2) The cerebral tissue significant changes in the cytology with the CO2 insufflation pressures higher than 8 mmHg. (3) Every air pressure group compared with comparison group: the average luminosity and average gray degree of ET and nNOS expression in cerebral tissue are significance (P<0.05). 12 mmHg air pressure group compared with other groups: the expression of ET in cerebral tissue is significance(P<0.05) and cerebral tissue appears edema . 12 mmHg air pressure group, 8 mmHg air pressure group compared with comparison group and 4mmHg air pressure group separately: the expression of nNOS in cerebral tissue is also significance (PO.05) and the change of cerebral tissue structure in electron microscope appears.Conclusion: A decrease in jugular venous circumfluence occurs pressures during endoscopic neck surgery with carbon dixide insufflation, possibly as a basilic reason changed CBF. the CO2 insufflation pressures can cause the cerebral hyperaemia, and hypoxia, cerebral tissures denaturation.And the study shows thatrto raise carbon dioxide pressure and prolong surgical time can lead ET and nNOS increasing in cerebral tissue,and then cause cerebral ischemia and cerebral tissue damage.