Clinical Study Of ATP With DIP Used For Controlled Hypotension

Background and PurposeControlled hypotension (CH) is an important measure which guarantee the safety of patients undergoing operation especially those with cardiovascular or cerebrovascular diseases, all kind of aneurysms, etc. for medicine used for CH , ideal medicine for CH should be effective; the onset and recovery tune of it are short;it shoud has no poisonous action, rebound hypertension and reflex tachycardia. And it shoud not make the body resist it quickly. Adenosine triphosphate (ATP) is an intrinsic vasodilation material which accords the standard basicly. Compared with sodium nitroprusside (SNP), ATP is better in regulation of circulation system; the O2 consumption of myocardial is less than that of SNP. It does not impair the autoregulation of cerebral blood flow and has little impact on pulmonary ventilation perrusion ratio than SNP and nitroglycerin(NG) . Thus, ATP shoud be a kind of medicine which is more suitable for CH than any other drugs which is used at present. However, ATP has some defects too. The dose is too big used for CH .so it is not convenient to use and the high dose of ATP produces large quantity of HPO42-. It combines with Ca2+ or Mg2+ in plasma and can result in unbalance of electrolyte, andaggravate the inhibition of the the cardiac conducting system (CCS), which is brought about by Adenosine (AD)--the decomposer of ATP. Therefore, Bradycardia, Premature Ventricular Contraction (PVCs) or I block of atrioventricular conducting happen on patients undergoing CH induced by ATP sometimes.The mechanism of ATP on CH is vasodilatation by itself and the action of AD. Dipyridamole (DIP) prohibits cells intaking AD and delays it's metabolism, so it can enhance the effect and decrease the dose of ATP. Experiments on animals have proven this theory therefore it is likely to reduce the side effects caused by the a big dose of ATP. For mankind, the dose of DIP has been reported but the dose of ATP has not been rerported when ATP withDIP used for CH. The aims of this study are (1) to certify the efficiency of ATP with DIP used for CH, (2) to find the accurate dose of ATP when ATP with DIP used for CH, (3) to observe the effect of ATP with DIP on Prothrombin Time (PT), (4) and the balance of O2 supply and demand of brain and (5) to observe the merits and defects of CH induced by ATP with DIP. So (6) provide a better solution for clinical CH.Materials and Methods:This study included 39 patients scheduled to undergo neurosurgical operation under general aneasthesia( ASA I ~ II, aged 37 18 years), excluding the patients with atherosclerotic coronary disease and abnormal prothrombin time (PT). They were randomly divided into 3 groups: Group A (ATP group,n=13) ; Group B (ATP with DIP group,n=13) and Group C(controlled group,n=13). General anaesthesia was induced by midazolam 2mg-kg"1, fentanyl 2Mg-kg~1, propofol 2mg-kg"', vecuronium 0.1 mg -kg'1 IV administered. General anaesthesia was maintained with isoflurane(0.5%~l%) inhalated, with continuous infusion of propofol (60 g-kg-1-mm-1), fentanyl (0.05g-kgmin-1), and using vecuronium (0.04mg-kg--130min) using an infusion pump. The PETCO2 was maintained 35~40mmHg during the whole general anaesthesia process. 0.1%~0.4%ATP was infused continuously at the rate of 120g-kg-1min-1 when CH was performed in Group A; hi Group B, DIP 0.3mg-kg-1 was intravenous injected slowly at 10~30min before infused ATP. When MAP was lowered to 70% ofbasedline and maintained 30min. Arterial and jugularis interna blood samples were taken immediately before CH (Ti), 5min after MAP being stable (T2), at the end of CH (T3) and 10min after ending CH (T4) for blood gas analysis, and T3 also for PT. During anaesthesia , the HR , MAP, ECG and SpO2 were continuously recorded by automatic monitor. During CH, the dose of ATP when the MAP began to decrease ; the dose of maintaining MAP; the time of MAP from down to stable and from end of CH to the 90% recovery of MAP were recored.ResultsComparison of effects of CH. hi group A, the onset dose, the maintaining dose and...