Effect Of Multiple Dosages Mannitol Administered On Brain Edema After Brain Contusion In Rats

Background and purpose Clinically,Patients with hypertension of ICP or possibility of raising ICP are subjected to theropy of mannitol .It is often noticed.So far,the machanism of mannitol have not been thoroughly verified yet.The effect of mannitol on intracranil pressure,cerebral blood flow,and other nervous functions has been verified on experiments and has been universely adopted.But we have found that the mannitol contained in blood can get into brain injurious area and result to local hyperosmolity,and raising content of water in brain tissue,and result to rebound of brain edema,when blood-brain-barrier is not complete.Many scholars have done a great deal of work,but their study has along limitations,that they has undirectly verified rebound phenomenon of mannitol ;Practically what is the relationship between density of mannitol in brain tissue and traumatic brain edema ?and how does it change?In this study,we applied traumatic brain injury animal model cause by controlled cortical compact and injections of mannitol to evaluate the effect of mannitol on brain edema by meassuring the changes of water,sodium and mannitol contents of brain tissue and to further provide a few basic theories for clinical mannitol treatment on traumatic brain injury.Methods Forty healthy adult rats all were subjected to controlled cortical impact and randomly divided into two groups,twenty in each one .One group suffering injection of mannitol was group M,another group without injection was group I.Each group was further devided into four team,five in each one.All rats were killed at 6,12,24,hours after injury for measuring brain water content ,sodium and mannitol contents in injurious area and healthy area of brain tissue.Results 1.Brain water content of group MI was significantly higher than group MH(p<0.01);2.Meantime ,in group MI,brain mannitol content at 24,48 hours after injury was significantly higher than the other twoteams(p<0.01).But there was no significant difference of brain water and sodium contents in group MI and II at 6,12 hrs after injury.3.There was significant difference in group MI and I I at 24,48 hours after injury (p<0.05).3.In group I I,brain water and sodium content at 24,48 hours after injury was significantly higher than the other to two time points(p<0.05).Conclusions 1. In the present study,it is not effctive that mannitol is administered as intravenous bolus(lg per kg body weight) as often as every 6 hours .in management of brain edema of rats after traumatical brain injury,if it iscontinuously administered,it will deteriorate brain edema. 2. If the time that mannitol is administered is more ,in edema area mannitol,water and sodium contents of brain tissue will be more.