The Effect Of Dexmedetomidine On Patients After Coronary Artery Bypass Grafting(CABG)in Intensive Care Unit (ICU)

Objective: Coronary atherosclerotic heart disease is the most commontype of organ lesions caused by atherosclerosis. It is also a serious commondisease that harms people's health. There are less people in our countrydeveloping the disease than Europe and the United States.But it has showedgrowth trend in recent years. In addition, the proportion of patientshospitalized has increased year by year. Coronary artery bypass grafting is aespecially large operation, heavy trauma to patients, and treatment costs arerelatively high.Sedation to patients after CABG is designed to let them comfortable,calm, no pain, and reduce the influence on hemodynamics in ICU. Mostpatients require sedation and analgesia to promote natural sleep, that canfacilitate assisted ventilation, and regulate the response to physiologicalstimuli (such as tachycardia and hypertension)[1.2]. Application of variousvasoactive drugs, sedative and analgesic to achieve the above goal atpresent[3.4]. But the medicine administrated alone or united may have adverseeffects on patients. For example, studies confirmed patients need deepsedation at the time of mechanical ventilation that will prolong the residencetime in the ICU[5], aggravating patients'mental and economic burden. Kresset al[6]proposed the process of sedation interrupted method could improvethe results.Propofol is the common anesthetic medicine for sedation administrated topatients after CABG in ICU at present. Because it can produce respiratorydepression, severe hypotension and other adverse reactions, the administrationtime is usually short, no more than24hours. What's more, propofol itself hasno analgesic effect, so it should be combined with opioids or other drugs forpain relief. Because of its moderate vasodilator action, it can cause patients obvious hypotension whose vital signs is unstable or myocardial reservecapacity is limited. Since propofol can cause a certain degree of respiratorydepression, the use of opioids at the same time may exacerbate respiratoryinhibition[7.8].Therefore, clinicians intermittently use propofol beforeextubation to reduce the occurrence of adverse reactions and to avoid thehappening of respiratory depression. That reduces the sedation effect ofpropofol when patients in high stress during the process. More, when evaluatepatients'nervous system function the administration of propofol must bestopped.DEX is a highly selective alpha2adrenergic receptor agonist (especialthe role on neurons receptor in the locus coeruleus nucleus). The clinicaleffective dosage of DEX used by intravenous route, its effects onhemodynamics can be predicted. More, it can not cause respiratory depressionand don't lower arterial oxygen saturation. The calm sleep state produced byDEX is similar to the natural sleep, the administration of DEX withoutstopping during the mechanical ventilation and the process of extubation.The purpose of the study is to evaluate the effects of dexmedetomidineon patients after coronary artery bypass grafting. Thus when patients aftercoronary artery bypass grafting are administrated to dexmedetomidine forsedation in clinical, there is enough evidence provided to prove that.Methods: The experiment was done within the ICU in cardiac surgerydepartment of the Hebei Medical University Second Affiliated hospital fromDecember2010to January2012.Subjects were randomly divided into experimental group (Group A)using DEX, and control group(Group B)using propofol. The using ofanesthetics and vasoactive drugs was based on the actual situation of patientsduring CABG. They would be different and could not be undertakenstandardization, so they could not be collected as experimental data. Patientsin group A began to use DEX when the chest was closed, usage of theanesthetic drug intraoperation began to reduce at the same time untilwithdrawal. DEX1.0μg/kg dose used over20minutes as a loading dose, and then to0.4μg/kg/h as maintenance dose. Patients would be transferredto ICU ofdepartment ofheart surgery, according to the need of patients to adjustthe DEX dosage, between0.2μg/kg/h and0.7μg/kg/h producing the calmeffect. If patients in group A needing deep sedation and the dosage of DEXalready to the recommended maximum dose0.7μg/kg/h, DEXadministrated could be combined with propofol. Administration time of DEXwas no more than24hours. Patients in group B with propofol intraoperation,continued to use it postoperation, adjustment of dosage and pumping rateaccording to the clinician's clinical experience and patients＇condition. Inaddition, physicians decided to apply other narcotics by directly talking topatients in the two groups or according to the signs of pain (such as sweating,heart rate increased, blood pressure raised).Blood pressure and heart rate were recorded every10minutes within thefirst hour of research drugs used, then to per hour once, until the drug stoppedused. Each subject carried the dynamic ECG machine for72hours,monitoring the changes of electrocardiogram. The administration ofvasoactive drugs, analgesics, diuretics, antiemeti, the time of mechanicalventilation and the retention period in ICU and so on in two groups werestatistically analyzed. It preliminarily discussed the effect of application ofDEX on patients after coronary artery bypass grafting in ICU.Results: The time of mechanical ventilation and length of retention inICU of two groups were no difference. Patients in group A showedtemporarily increasing in systolic blood pressure then decreasing to standardlevel or below standard value fluctuating. Patients in group B showed bloodpressure increased then above baseline level. The occurrence of hypotensionof patients in group A was more than those in group B. The two groups had nohappeness of bradycardia. There was no difference in statistical analysis aboutheart rate. The partial pressure of oxygen in arterial blood in two groups wasno difference. At the time of extubation and6h after that it was higher thanpreoperation in group A. There was no difference in group B. The occurrencerate of cardiac arrhythmias and changes of ST segment in two groups were similar. The usage of furosemide and antiarrhythmics in group A was less thangroup B. The administration of analgesics, beta blockers, alpha agonists,insulin and antiemetic agents was similar in two groups. Troponin I (cTnI)andrenal function index urea nitrogen(BUN),creatinine(CREA) were higher thanpreoperation,but no obvious difference.Conclusions: Compared to propofol patients administrated DEX wassafe and effective for sedation after coronary artery bypass grafting.