Effects Of Dexmedetomidine On General Intravenous Aneasthesia For The Patients With Mild Liver Dysfunction

Background and ObjectiveLiver is the largest organ in the body with a very complex physiological and biochemical function, the pathophysiology of patients with liver dysfunction is variable. Anesthesiologists need to consider both the change of anesthetic drugs metabolism and narcotic drugs on liver function when liver is dysfunctional, in order to choose the best anesthetic solution and anesthesia management for the patients with liver dysfunction. General anesthesia is considered more in order to avoid epidural hematoma which could coursed by poor clotting mechanism in liver dysfunction patients. General intravenous anesthesia has become the main method of anesthesia for patients with liver dysfunction because of rapid induction of anesthesia, anesthesia process smooth, wake up faster and so on. The ideal anesthetic drugs for patients with liver dysfunction should has the minimal effect on liver blood flow and metabolism, ensure hemodynamics stable and recovery phase smooth.Dexmedetomidine is a potent and highly selective alpha2-adrenoceptor agonist, it provides dose-dependent sedation, analgesia, anxiolysis, and has little respiratory depression. Dexmedetomidine can reduce the dose of propofol and opioids in anesthesia induction and maintenance significantly to make the process more stable, improved recovery process after anesthesia and reduce the happenness of restlessness, shivering, nausea and vomiting postoperative.There were few of studies about the effect of dexmedetomidine on patients with liver dysfunction in spite of it’s more estensive clinical application. Therefore, the purpose of this study was to evaluate the effects of dexmedetomidine on patients with liver dysfunction, in order to provide a reference for clinical anesthesia work.Materials and MethodsSixty ASA physical status II adults, aged18to60years, weighing50-80kg, undergoing elective surgery with mild liver damage and were randomly divided into three groups, C group (0.9%NaC1solution injection, n=20); Test groups given Dex before induction (administration time10min); D1group (loading dose of0.4μg·kg-1dexmedetomidine, then pumping the dose of0.2μg·kg-1·h-1dexmedetomidine continuous with intravenous pump, n=20); D2group (loading dose of0.8μg-kg-1dexmedetomidine, then pumping the dose of0.4μg·kg-1·h-1dexmedetomidine continuous with intravenous pump, n=20).All patients had not preoperative drugs, after patients got into the operating room, some indexes such as electrocardiogram (ECG), noninvasive blood pressure (NIBP), pulse oxygen saturation (SpO2) were monitored, the bispectural index (BIS) with the depth of anesthesia monitor and partial pressure of carbon dioxide in endexpiratory gas (PETCO2)After the loading dose, all patients were infused midazolam0.5mg·kg-1, fentanil3μg·kg-1, vecurium O.1mg·kg-1, propofol TCI started at2.0μg·ml-1and increase the concentration gradually until CSI dropped50and then tracheal intubation.Record HR, MAP before the intravenous injection of Dex,1min after the Dex,2min before and1min after the tracheal intubation, the surgery begins,30min,60min and90min after the start. Record propofol concentration and maintain a constant dose of remifentanil(0.2μg·kg-1·h-1). Record the time of wake up and whether there is restlessness.SPSS13.0version was used for statistical analysis. Measurement data was signified by mean±standard deviation(x±s). Aanalysis of variance was used to compare the repeated measurement data within group and t test was used to compare between groups. Count data using chi-square test.ResultsAfter the infusion of Dex, MAP decreased in group D1and increased in group D2significantly (P<0.05); HR decreased significantly in the two groups (P<0.05). After induction of anesthesia, MAP was significantly higher in group D1and D2compared with group C (P<0.05), HR also decreased significantly (P＜0.05). At the time of1min after intubation and the beginning of surgery, there was no significant changes in MAP,but HR decreased significantly (P＜0.05) in group D1and D2,compared with group C. During surgery, MAP and HR were significantly higher in group D2(P<0.05). The Intraoperative TCI concentration of propofol in group Di and D2was significantly lower than group C (P<0.05), and group D2was less than group D1(P＜0.05). In the recovery period,4cases of irritability occurred in group C and none in group D1and D2.3cases of atropine intervention in group D2and none in group D1and C. None needs Phenylephrine.Conclusion1、Loading dose of0.4μg·kg-1Dexmedetomidine can maintaine stable hemodynamics and reduce stress when used for patients with mild liver dysfunction.2、Pumping the dose of0.2μg·kg-1·h-1Dexmedetomidine dose not affect revovery process in patients with mild liver dysfunction and can reduce the incidence of irritability in liver disease patients during anesthesia recovery.