Protective Effects Of Mild Hypothermia Induced By Infused Intravenous Ice-cold (4℃) Fluid On Rabbits With Focal Cerebral Ischemica

Objective: To study the protective effects of infused intravenous ice-cold (4 C) normal saline on rabbits with focal cerebral ischemica.Methods: Thirty rabbits were randomly divided into three groups after making the models of cerebral middle artery occlusion. The mild hypothermia group (II) was induced by surface cooling with ice packs, ice-cold (4 C) saline group (III) was infused 4 C normal saline intravenously over 24h and the control group (I) was put in the room with temperature 22 C. Rabbits in the mild hypothermia groups were cooled to 34 C to 35 C and maintained for 24 hours. All rabbits were monitored cerebral temperature (Tc), blood pressure (BP), mean arterial pressure (MAP) intracranial pressure (ICP), cerebral perfusion pressure (CPP) and central venous pressure (CVP).Results: Target temperature in both hypothermia groups was achieved in (48.0 7.1) min (II) and in (52.3 8.9) min (III), no difference in the both groups was observed (P>0.05). Group III had a significantly lower ICP and greater CPP during cooling. ICP in III group was reduced form (12.5 3.0) mmHg to (11.0 2.2) mmHg (12h) and (10.5 2.0) mmHg (24h), the CPP significantly increased form (75.9 6.2) mmHg to (86.3 7.3) mmHg (2h), (81.9 3.9) mmHg (12h) and (80.9 5.1) mmHg (24h). Compared with the controlling group, ICP in both groups were significantly decreased and CCP were significantly increased (P<0.05). But the CCP in the III group was significantly higher than in the II group (P<0.05).Conclusion: These results indicated the mild hypothermia infused intravenous ice-cold normal saline may decrease ICP and increase CPP after focal cerebral ischemica. Our preliminary data show that ice-cold normal saline infused intravenous is a useful and safe method.