The Use Of Controlled Hypotension In The Operation Of Neurosurgery

Objective: To compare the effect of multiple drugs with single drug in controlled hypotension. Method : 42 patients of ASA Ⅱ-Ⅲare divided into four groups, they are going to take the operation of intracranial aneurysm(IA) under general anesthesia. When getting into the brain essence where it is close to aneurysm, we,ll take controlled hypotension(CH). Group I is given Nitroglycerin (NTG) 1.2-1.5 ug·kg-1·min-1, Esmolol 50-60 ug·kg-1·min-1,then adjusting the speed of NTG and Esmolol so as to get to the aimed blood pressure which keep the MAP at the leve of 60-65mmHg. When you have finished clipping the aneurysm, we,ll stop using the drugs immediately and wait for its self-recovering; GroupⅡis given NTG2.5-3 ug·kg-1·min-1; Group Ⅲis inhaled Isoflurane with the concentration of 1.5%-2% and TCI Propofol at the speed of 0.4-0.7 ㎎·kg-1·min-1,the method and the degree are the same as group I; Group Ⅳis only inhaled Isoflurane with the concentration of 4%-5%.Record MAP,HR and RPP before CH and after CH for 5 minutes,10 minutes,20minutes,and at the moment of clipping,and after stopping CH for 10 minutes and 30 minutes separately. Meanwhile take a record of the total dosage of NTG, the concentration of Isoflurane and the inducing time which means the time from beginning CH to get to the aimed pressure. Result : In Group I, the total dosage of NTG is 49.0 ±4.6 ug·kg-1and the inducing time is 3.9±0.3min,while it is 108.0 ±18.7ug·kg-1and 6.3±0.4min in GroupⅡ.Group I has reduced the dosage of NTG by 54.6% compared with Group Ⅱ,so there is significant difference between the two groups(p<0.05). In Group Ⅲ,the concentration of Isoflurane to the aimed blood pressure is 1.8%±0.2%, and the inducing time is 4.3±0.3min,while it is 4.0%±0.4% and 6.7±0.5min in Group Ⅳ.It means that Group Ⅲhas reduced by 55.0% compared with Group Ⅳ,the differences are also significant (p<0.05). There is no significant differences of the blood pressure between the groups after CH.In Group Ⅱthe HR increases fast , by 18% before CH at the most.However,the HR in the Group I is slower and more stable than before(p<0.05).So there is significant difference between the two groups(p<0.05).There is no significant difference of RPP before CH in each group (p>0.05). After CH it is falling a lot inGroupⅠⅢandⅣ(p<0.05). But it changes unconspicuous in GroupⅡ. Discussion : According to the statistics materials, the cerebral vascular disease is the second death factor among our citizens. Intracranial aneurysm(IA) lies in the first place of the bleeding cerebral vascular disease which counts for about 60%. so it has greately endangered the human's life security.Today most of IA are treated through operation. CH is benefit to the operation by reducing the bleeding amount and falling the tension of blood vessel. But it will take a large dosage when using a single drug in CH and often comes along with some side effects. It restricts the use of CH in IA operation.So many scholars are trying to find an ideal medicine. But no one has found yet. Therefor the method of multiple drugs has opened up a new sky for CH. NTG takes the esterification reacts to release NO by itself and wide the blood vessels. Nevertheless, when the pressure is fallen too much,it could increase the sympathetic tension via reflectiveness, which will result in the fast rhythm of heart beat and increasing myocardium oxygen consumption. By the way, the large dosage of NTG is also the reason for pulsative headache after operation.The side effect could be eliminated by Esmolol which is a type of highly selective ?1-blocker. In this article the blood pressure is lowered down in Group Ⅱbut the HR is too fast. in Group I due to Esmolol's blocking of the reflectively fast heart beat, the HR is slowed down ,the blood pressure is steady. Esmolol accompanied with NTG can shorten the inducing time also. Esmolol could increase the patient's sensitivity to NTG, so the dosage of NTG is reduced by 54.6%. RPP in Group I is remarkably lower than GroupⅡ.As a result Esmolol accompanied with NTG could protect the myocardium with its slow HR and low RPP. This research has testified that Esmolol could effectively antagonize the fast rhythm of heart beat caused by NTG in CH, meanwhile it could reduce the inducing time and the dosage of NTG. Thus it has become an effective, convenient and safe method for CH in the clinical anesthesia. Isoflurane is one of the sucking narcotic drug of halogen families and it has protecting effect on neuron. But if Isoflurane is used alone in CH, the concentration is usually very high about 4%-5%, and the function is so weak that even deepened the depth of anesthesia you can not get your purpose. It has a huge difference among theindividuals. What 's more , inhaling a large amount of Isoflurane might cause restless after the operation and reviving delay. In order to strengthen the function of Isoflurane as well as to avoid the side effects in CH, we have chosen propofol on the basis of Isoflurane. Propofol is a new type of venous drug which can widen the peripheral vessels. It can eliminate the free radicals, suppress the activity of NMDA receptor, also it can reduce piling up of excitability amino acids and enhance the function of GABA.As a result, it has protecting effect on neuron. It is mentioned in this article that inhaling Isoflurane with the concentration of 1.5%-2.0% and then compound with propofol will reach our goal easily. Besides shortening the inducing time and reducing the myocardium oxygen consumption, it can also reduce the concentration of Isoflurane by 55.0% so that it could keep important organs from damaged by its high concentration. As it shows, Propofol accompanied with Isoflurane is much better than Isoflurane alone. It could overcome the side effects. It is simple in management and well-controlled. The most important is that it is safe and little disturbed on physiology. Conclusion: We use four methods to study CH with 42 patients...