The Effects Of The Change Of Blood Pressure And Vasoactive Drugs On Middle Cerebral Artery Blood Flow In The Patients Undergoing The Off-pump Coronary Artery Bypass Grafting Surgery

With the improvement of people's living standard,the incidence of coronary heart disease is increasing year by year and the age of onset is younger trend.The development of coronary artery bypass grafting technology brings the gospel to the coronary heart disease patients.At present,coronary artery bypass grafting surgery mostly operates in non-extracorporeal circulation,reducing the interference of organs and physiological function of patients with cardiopulmonary bypass,but it puts forward higher requirements to the anesthetic technique.In off-pump coronary artery bypass grafting surgery,surgical operation in general need to move the heart,it will not only affect the heart function,but also cause coronary artery spasm,leading to the sharp fluctuations in blood flow,even serious hypotension,ventricular fibrillation,cardiac arrest,etc.And then it will affect cerebral blood flow,leading to the occurrence of cerebral low perfusion,increasing the postoperative neurological complications incidence,affecting the patient postoperative recovery.In order to maintain hemodynamic stability,sometimes the use of vasoactive drugs is inevitable,however,it will cause the change of cerebral blood flow.Positive inotropic drugs is conducive to increase blood pressure,and also increase cerebral blood flow to a certain extent,but the contraction of blood vessels may also reduce the blood supply to the brain,affect cerebral metabolism,the reason may be related to the dosage of vasoactive drugs.Therefore,monitoring the middle cerebral artery during the operation,studying on how the cerebral blood flow changes with blood pressure and the impact of vasoactive drugs on cerebral blood flow during the off-pump coronary artery bypass grafting surgery,which caneffectively guide our clinical work.Objective:Using the transcranial Doppler?TCD?to monitor the right middle cerebral artery blood flow of 100 cases of patients who are undergoing off-pump coronary artery bypass grafting surgery,evaluating the effect of the changes of blood pressure and vasoactive drugs on middle cerebral artery blood flow of the patients who are undergoing the off-pump coronary artery bypass grafting surgery,in order to provide a basis for our clinical work.Method:Selecting 100 cases of patients who are undergoing off-pump coronary artery bypass grafting in the second hospital of Hebei Medical University from April 2014 to February 2015,using the TCD continuely to monitor and record the systolic blood pressure?SBP?,diastolic blood pressure?DBP?,mean arterial pressure?MAP?,BIS value,heart rate?HR?and the relevant hemodynamic parameters of MCA: mean velocity?Vm?,peak systolic velocity?Vp?,end disatolic velocity?EDV?,resistance index?RI?and DM value of the patient at the time of entering operation room?T₀?.Recording the value of SBP,DBP,MAP,HR,BIS,Vm,Vp,EDV,RI and DM at each time point of after endotracheal intubation,after sawing breastbone,left anterior descending coronary artery?LAD?,right coronary artery?RCA?,posterior left ventricular branch,left circumflex?LCX?,diagonal branches,side clamp,open,after the procedure?the difference with 10 mmHg of SBP as the benchmark?.Record the indicators above?when hypotension occurs?blood pressure rise and sfter using the vasoactive drugs?Ephedrine,Norepinephrine,Calcium gluconate?.Results:1 The correlation of blood pressure?SBP,DBP,MAP?of the patients undergoing the off-pump coronary artery bypass grafting surgery and cerebral blood flow?Vm,Vp,EDV,DM?.1.1 Comparing with T₀,the value of SBP,DBP,MAP,Vm,Vp and EDV at the time point of T₁^T9 decrease,the difference were statistically significant?P<0.05?.1.2 Conducting analysis on the correlation between DM and Vm,Vp,EDV respectively of all the time point,we find that there were positive correlation between DM and Vm,Vp,EDV,the correlation coefficient were0.837,0.774 and 0.488 respectively.1.3 Through conducting analysis on the correlation between the changes of blood pressure ?SBP?the value of SBP at the time of entering the operation room minus the value of SBP at each time point?,?DBP?the value of DBP at the time of entering the operation room minus the value of DBP at each time point?,?MAP?the value of MAP at the time of entering the operation room minus the value of MAP at each time point?and the changes of cerebral blood flow ?Vm?the value of Vm at the time of entering the operation room minus the value of Vm at each time point?,?Vp?the value of Peak at the time of entering the operation room minus the value of Peak at each time point?,?EDV?the value of EDV at the time of entering the operation room minus the value of EDV at each time point?,?DM?the value of DM at the time of entering the operation room minus the value of DM at each time point?,it can learn that there were no correlation between the changes of blood pressure and cerebral blood flow among all the time point except the time point of T6.There were negative correlation between ?SBP,?DBP,?MAP and ?Vm?the correlation coefficient were 0.422,0.390 and0.433 respectively,P < 0.05?at the time point of T6;there were negative correlation between ?SBP,?DBP,?MAP and ?Vp?the correlation coefficient were 0.364,0.419 and 0.424 respectively,P < 0.05?at the time point of T6;there were negative correlation between ?SBP,?DBP,?MAP and ?DM?the correlation coefficient were 0.339,0.326 and 0.382respectively;P<0.05?at the time point of T6.2 The effect of vasoactive drugs on cerebral hemodynamic Vm.2.1 After the administration of ephedrine at dose of 3mg,6mg or 9mg,the value of MAP,Vm,EDV increase,there was statistical significance?P<0.05?when comparing with the value before administration;there was no statistical significance of RI value?P> 0.05?when comparing with the valuebefore administration2.2 After the administration of Calcium gluconate at dose of 1g,the value of MAP,Vm and EDV increase,RI value decrease,there was statistical significance?P<0.05?when comparing with the value before administration.2.3 After the administration of Norepinephrine,when the single dose was within 16 ? g,the value of MAP,Vm and EDV increase,RI value decrease,there was statistical significance?P<0.05?when comparing with the value before administration;however,when the continuous single dose?within5 minutes?is beyond 16?g,MAP and RI value increase,Vm EDV decrease,there was statistical significance?P < 0.05?when comparing with the value before administration.Conclusion:1 For the patients who were undergoing the off-pump coronary artery bypass grafting surgery,there was correlation between the changes of blood pressure and cerebral blood flow when conducting the coronary of left circumflex?LCX?,furthermore,the intensity of correlation between MAP and cerebral blood flow was the most strong.Thus,MAP was the most sensitive indicator to estimate the condition of cerebral perfusion.2 Among all the relevant hemodynamic parameters of MCA,there was significant correlation between Vm and DM,so we suggest that it may be more precise to calculate the value of DM through Vm,and more the correlation coefficient of ?Vm and the change of cerebral blood flow was the most significant,thus we can regard Vm as the most sensitive reference index among all the relevant hemodynamic parameters of MCA.3 For the patients who were undergoing the off-pump coronary artery bypass grafting surgery,the cerebral blood flow would increase as well as MAP after the administration of Ephedrine,Calcium gluconate and Norepinephrine?when the single dose was within 16?g?;the cerebral blood flow would decrease,although MAP increase,after the administration of Norepinephrine?when the continuous single dose?within 5 minutes?is beyond16?g?.