Effects Of Two Drugs On Cerebral Oxygen Metabolism During Controlled Hypotensions In Cerebral Aneurysm Clipping Surgery

Objective To compare the effects of controlled hypotensionsrespectively with nicardipine and nitroglycerin on cerebral oxygenmetabolism in cerebral aneurysm clipping surgery.Methods40patients, involved in this randomized, controlled anddouble-blind trail, undergoing cerebral aneurysm clipping surgery,were devided into Nicardipine(Ⅰ) Group and Nitroglycerin(Ⅱ) Groupwith20cases each. All cases, without major organs dysfuction,without the history of other diseases and long-term taking drugs,no cerebral arteriovenous malformation, ASA gradedⅠ-Ⅱ, Hunt-HessⅠ. Reoperation and multiple aneurysms patients were excluded. Allthe surgeries performed within3days after the aneurysms ruptured.Both groups were anesthetized total intravenously, to give propofolby target controlled infusion. Initial target-controlledconcentration was set to4.0μg/ml, and continuously adjusted tomake their mean arterial pressures(MAP) reduced less than5%oftheir basic values before controlled hypotensions. Cerebral stateindex(CSI) was maintained in the range of40to60meanwhile.Controlled hypotension was started at the moment of cuttingduramater. GroupⅠwas treated with nicardipine (10-30) μg/kg,followed by (0.5-7) μg/kg min continuous infusion into whereasGroup Ⅱ was administrated with nitroglycerin1μg/kg min, andgradually added to (3-6) μg/kg min continuous infusion into. Adjusted according to their blood pressures to make their MAPreduced by25-30%within5min compared with their basic values.Blood gas analyses were performed at the time of T0, T1, T2and T3,respectively corresponding to the moment of cutting duramater,aneurysm isolation completed, aneurysm clipping done and20minafter controlled hypotension, by taking samples from radicalarteries and jugular vein bulbs. The values of arterial partialpressure oxygen(PaO2), jugular bulb venous partial pressureoxygen(PjvO2), arterial oxygen saturation(SaO2), jugular bulbvenous oxygen saturation(SjvO2), arterial haemoglobin(Hab),jugular bulb venous haemoglobin(Hjvb) were recorded in order tocalculate the values of arterial-jugular bulb venous oxygen contentdifference(Da-jvO2) and cerebral oxygen extraction rate(CERO2)according to the formulas. Controlled hypotension was stoppedimmediately once cerebral aneurysms were clipped. The inhalationof oxygen flow was controlled at1.5L/min, and oxygen concentrationat50%during the surgeries. Room temperature was kept at24-25℃, relative humdity of40-50％. Variable temperature blankets wereused to maintain the patients’ nasopharyngeal temperatures between36-37℃. Fluid intake and respiratory parameters were adjusted tomaintain their central vein pressures(CVP) between5-10cmH2O and thepartial pressures of end-tidal carbon dioxide(PetCO2) in the rangeof30-35mmHg during opening the skull.Rsecults Blood pressures were kept at a desirable level withoutsignificant difference (P>0.05). Heart rates in both groups increased obviously (P<0.01) without intergroup difference(P>0.05)during controlled hypotensions. Compared with T0and T3, the valuesof SjvO2at T1and T2increased significantly(P<0.05or<0.01) whereasthe values of Da-jvO2and CERO2decreased significantly (P<0.01) ingroupⅠ. The values of SjvO2, Da-jvO2and CERO2at T1and T2were nosignificant difference with their values at T0and T3in group Ⅱ(P>0.05). Compared with group Ⅱ, the values of SjvO2at T2and T3were significantly higher (P<0.05) whereas the values of Da-jvO2andCERO2were significantly lower (P<0.05) in group Ⅰ.Conclusion Both nitroglycerin and nicardipine can be safely usedfor controlled hypotensions in cerebral aneurysm clipping surgery.But the later can effectively decrease cerebral oxygen metabolismand improve cerebral oxygenation which is superior to the formerin terms of cerebral protection.