Influence of moderate hypothermia on cerebral oxygenation in pigs with intracranial hypertension

BACKGROUND： Moderate hypothermia is one of the effective therapeutic methods for head injury in recent years, there are many mechanisms of moderate hypothermia for brain protection, and its influence on cerebral oxygenation is also one of them. OBJECTIVE： To observe the influence of moderate hypothermia on cerebral oxygenation of animals with acute intracranial hypertension, and further investigate the protective mechanism of moderate hypothermia. DESIGN： A randomized controlled trial. SETTING： Department of Neurosurgery, Renji Hospital affiliated to the Medical College of Shanghai Jiao Tong University. MATERIALS： Twenty healthy little pigs, either male or female, weighing 4.5-5.5 kg, were used. Neurotrend-typed multiparameter monitoring system （Diametrics Company, British）; CMA/100 micro-injection pump （Carnegie Company, Sweden）. METHODS： The experiment was conducted in the Changzheng Hospital affiliated to the Second Military Medical University of Chinese PLA in November, 2001. The pigs were randomized into two groups： the normothermia group （control group, n =10） and moderate hypothermia group （n =10）. ① Bilateral femoral arteries were separated, one was connected to pressometer for monitoring mean arterial pressure （MEP）, and the other for analysis of blood gases [including peripheral blood pH value, arterial partial pressure of carbon dioxide （PaCO2）, arterial partial pressure of carbon dioxide （PaCO2）, HCO3-]. ② Rectal temperature was monitored with mercurial thermometer. ③ Intracranial pressure was monitored using Camino optic ICP probe placed in the subdural space. ④ Neurotrend multiparameter monitoring sensor was inserted into the white matter for about 4 cm to determine cerebral perfusion pressure （CPP, CPP=MAP（ICP）, brain tissue partial oxygen pressure （PO2）, partial pressure of carbon dioxide （PCO2）, HCO3- and brain temperature. The rectal temperature of animals in the moderate hypothermia group was lowered to 34 ℃ using ice bags, and the body temperature was maintained at 33-35 ℃ for 2 hours. The changes of the parameters were observed continuously, and the pigs in the normothermia group were not treated with cooling. MAIN OUTCOME MEASURES： ① MAP, ICP, rectal temperature, CCP; Indexes of cerebral oxygenation detected with Neurotrend-typed multiparameter monitoring system; ② Results of blood gases analysis in the moderate hypothermia group. RESULTS： All the 20 pigs were involved in the analysis of results. ① MAP, ICP, rectal temperature, CCP and indexes of cerebral oxygenation： In the moderate hypothermia group, the ICP after cooling was obviously lower than that before cooling [（3.31±1.19）, （5.33±0.95） kPa, P 〈 0.05], CCP was higher, brain tissue PCO2 [（12.03±1.73）, （10.59±2.01） kPa, P 〈 0.05], and brain tissue pH value was higher [（7.03± 1.63）, （9.40±1.30） kPa, P 〈 0.05], whereas the brain temperature was decreased as compared with that before cooling [（34.9±0.3）, （37.2±0.2） ℃, P 〈 0.05]. ② Results of blood gases analysis in the moderate hypothermia group： There were no significant differences in the parameters of peripheral arterial blood gases analysis before and after cooling in the moderate hypothermia group （P 〉 0.05） CONCLUSION： Moderate hypothermia will not impair the cerebral oxygenation, and it can reduce brain tissue CO2 and decrease brain tissue acidosis.

Study on difference between intravascular cooling system and traditional moderate hypothermia in patients with severe traumatic brain injury

Objective To study difference between intravascular cooling system and traditional moderate hypothermia in patients with severe traumatic brain injury. Methods Eighty sTBI patients were randomly divided into intravascular hypothermic groups (IVT) and traditional moderate hypothermia groups(HT) . Inclusion criteria included a Glasgow Coma Scale(GCS) score ≤8 and time from injury to admission must be within 12 hours.

Experimental and Clinical Research of Myocardial Protection Effect Using MHBC Perfusion

Objectives To determine themyocardium -protecting effect of medium hypothermalblood cardioplegia (MHBC); further demonstrates thatthe optimal temperature between these hypothermaland normothermic can overcome the disadvantages;and thus discovers a more effective myocardium pro-tecting method. Methods Section 1: 14 mongreldogs (15-20 kg) were randomly divided into twogroups: experimental group and control group; car-dialpulmonary bypass was conventionally instituted,moderate hypothermia blood cardioplegia was used inexperimental group, Blood samples from right atriumtaken for examination of lactate dehydrogenase (LDH)creatine kinase(CK-MB) and Topin Ⅰ(cTn-Ⅰ). speci-mens of left ventricular subendocardial myocardiumwere biopsied to observe changes of ultrastructure.Section 2: 24 patients were randomly divided into twogroups and both groups received two types of treat-ment (same as Section 1) after aorta cross-clamp(ACC). Biochemical index and Clinical observationwere caculated as the indicators. Results In the ex-perimental research, LDH, CK-MB, cTn-Ⅰ were foundincreased afer reperfusion in both groups, but the ex-tent of changes in experimental group is tiny (statisti-cal difference). Compared with control group the effectof MHBC on cardial function is litile; the ultrastruc-ture. of cardiac muscle has no obvious change. In theclinical research, compared the test results of venousblood drawn before CPB, after beating recovery andafter CPB, CBC perfused group (LDH, CK-MB leak-age and cTn-Ⅰ value increase.) compared with MHBCperfused group had no remarkable difference (P>0.05), but at the result of clinical observation: MHBCperfused group had red, soft hearts after cardiac arrestbut CBC perfused group had pale, spasmatic heartsafter cardiac arrest; 0 case in MHBC perfused groupand 3 cases in CBC perfused group had twitch-re-moving beat recovery; 11 cases in MHBC perfusedgroup and 3 cases in CBC perfused group recoveredsinus heart rhythm after surgery; average consumptionof lidocaine was 16.67 (±55.28) mg for MHBC per-fused group and 118.33(±82.65) mg for CBC perfusedgroup (P<0.01) afer surgery; 4 cases in MHBC per-fused group and 11 cases in CBC perfused group suf-fered arrhythmia after surgery. Conclusions As anew myocardium - protecting method, MHBC perfusionin combination with natural body temperature drop ofCPB is worth clinical dissemination and application.