| Objective To establish a new animal model of severe lateral fluid percussion brain injury in rabbits. Mild hypothermia therapy was employed on it. Analyze the validity of this model and study on the effects of hypothermic intervention to the cerebral morphological, pathophysiological, biochemical and imaging alterations. To demonstrate the cerebral protective effects of mild hypothermia therapy to STBI and providing some unique data for studies in the future.Methods 44 adult male New Zealand white rabbits were divided into 4 groups, and a two-phase-work was designed. 3 groups were involved in Phase 1: A-Control(no percussion), 6 rabbits;B-Trephination of 4mm diameter cranial window and fluid percussion applied, 10 rabbits;C-Trephination of 7mm diameter cranial window and fluid percussion applied, 14 rabbits. Phase 2: Basing on the conclusion of phase 1, 14 rabbits were distributed into group D with trephination of 7mm diameter cranial window and fluid percussion applied followed by mild hypothermia. Uniformed anesthesia and surgical process were administered to the 4 groups and standardized LFPI (1.7 atm~2.1 atm) applied;subsequently mild hypothermia (34℃ ±1℃, rectal temperature) achieved by surface cooling within 1.5 h andmaintained at least 6 h post injury in group D. Dynamic acute phase physical signs such as R, HR, T (rectal and cerebral), defecation and urination conditions and even muscular tension were noted as well as microdialysis monitoring were utilized to investigate the biochemical fluctuations in ECF during the first 6 h post injury. Neurological function deficit scale and cerebral water content examination together with general and LM examination were also executed at the moment of 24 h post injury. Additional MR and EM observation were performed in group C and D. Differences between groups were analyzed by statistic measures or macrographic examinations.Results 1.Group C compared with group B upon the same impact intensity, from the point of the animal's manifestations post injury, the former has higher mortality, worse consciousness, markedly abnormality of respiratory mode and muscular tension caused by the insult of brainstem as well as the interference to peripheral organs. 2.On the view of cerebral metabolic monitoring about biochemicals in ECF: there is stronger effect on energy metabolism disorder, inducing excitotoxicity and the extent of cellular destroys in group C. 3. And even to the efficacy of aggravating neurological function deficits and brain edema post injury, moreover macroscopic and microscopic observation, or along with MR examination on evaluating the severity of damage, group C is recommended. The EM findings collected from group C and group D accorded with the ultramicroscopic alterations of clinical STBI. 4.1n the process of evaluating the benefits of mild hypothermia therapy, there are satisfactory effects of more slightly injury by pathological and imagingobservation in group D. The second insult post STBI of animals in group D has been improved by this specific therapeutic method through the approaches described as below: meliorate energy metabolism, relieve the cellular sufferings, inhibit the progress of excitotoxicity and brain edema. Conclusion 1-In the conditions of 7 ? diameter cranial window and impact intensity of 1.7 atm ~2.1 arm, lateral fluid percussion model of severe traumatic brain injury in rabbits can favorably simulate the clinic manifestations, histological changes, imaging findings and secondary insults as well as brain edema, ischemia, metabolic fluctuations. It is credible to evaluate therapeutical effects of mild hypothermia on this model. 2.The study demonstrated that administering mild hypothermia in the early phase is a protective treatment to severe traumatic brain injury. 3.The results provide useful references to later studies.
|
PDF Full Text Request