| Background and ObjectiveGeneral anesthesia induction is a period of high incidence of anesthetic complications including high blood pressure, abnormal heart rhythms, regurgitation and aspiration, anesthesia airway spasm and drug allergies, etc. It is the most dangerous stage of the entire anesthesia process, which is often called the aircraft’s take-off stage by anesthesia physicians.The hemodynamic volatility caused by the stress reaction when intubating is one of the important risk factors in this period.Intubation stress response is a phenomenon that the body’s blood catecholamine concentration escalates significantly higher in the process of laryngoscope placement or endotracheal intubation during induction of general anesthesia, which results in hemodynamic volatility. Generally speaking, its mechanism is the throat and trachea receptors are stimulated by mechanical stimulation that causes the body’s stress response when intubating--It is the hyperactivity of sympathoadrenal system that causes the short-term hemodynamic volatility:hypertension, tachycardia or arrhythmia. This occurs in healthy people may induce cardiovascular and cerebrovascular accidents, especially in patients combine with high blood pressure, heart dysfunction and cerebrovascular diseases, can seriously jeopardize the life safety of these patients. To solve this problem, the clinicians have used some methods such as surface anesthesia or nerve block; using advanced visualization intubation equipments to reduce the mechanical stimulation; early use of prophylactic drugs, including vasodilators, β-blockers, calcium channel blockers, opioids and α2agonists, etc. However, every method has its certain drawbacks or limitations.Dexmedetomidine belongs to imidazole derivative. It is a new type of highly selective, highly specific α2adrenoceptor agonist, which has the impacts of sedation, analgesic, anti-anxiety, anti-sympathetic activity, hemodynamic stability and mild respiratory depression. In addition, the advantage of its short half-life period gives it a wide range of clinical value. It has been reported that dexmedetomidine could reduce perioperative plasma concentrations of catecholamines and promote perioperative hemodynamic stability abroad, while there are relatively less research reports in our country. The purpose of this research is to study the influences of different doses of dexmedetomidine on endotracheal intubation stress response, and to assess the clinical effect of inhibiting the intubation stress response. We hope it would provide a theoretical basis for rational use of the drug and clinical spread.Materials and MethodsWe chose90patients who undergoing elective surgery under general anesthesia intubation, aged18to60years old, weighing40～80kg, ASA Ⅰ～Ⅱ grade, Improvement of Mallampati Ⅰ～Ⅱ grade. All the patients were randomly divided into three groups:the control group, experimental group D1and group D2. Every group had30cases.30minutes before induction we gave give penehyclidine O.Olmg/kg through intravenous approach. Then we gave normal saline (NS) in group C, while gave Dex0.5μg/kg and0.75μg/kg through intravenous infusion in Di group and D215minutes before induction,respectively (Dex concentration is4μg/ml,10min to complete).5minutes after that, we began the process of induction of anesthesia, intravenous injection of midazolam0.05mg/kg, fentanyl4μg/kg,3minutes later proprfol is TCI,and plasma target concentration is5μg/ml, and when the BIS value dropped50to55,injected cisatracurium0.2mg/kg. When the muscles were fully relaxed, the intubation was performed with the ordinary direct laryngoscopy by the same anesthesiologist. All of the intubations were completed only once, otherwise the case would be excluded. Recorded the intubation time and removed those time more than30seconds. During the maintenance phase we took continuous intravenous infusion of propofol4-8mg/kg·h-1and remifentanil0.1-0.2μg/kg·min-1. Intermittent intravenous cisatracurium0.07mg/kg to maintain muscle relaxants and routine analgesic after the surgery. Observed and recorded15minutes after the burglary (T0), before the induction of immediate (T1), immediately before intubation (T2), lminutes after intubation (T3),3minutes (T4),5minutes (T5), mean arterial pressure (MAP), heart rate (HR), and at To, T4time extracted radial artery3ml to detect the concentration of plasma catecholamines (adrenaline AD and noradrenaline NA).All experimental data using the SPSS17.0statistical software for processing. All measurement data were expressed as mean±stand deviation (x±s), one-way ANOVA was used to the comparison between multiple sets of measurement data, Multiple of the mean number of pairwise comparisons with LSD-t test, measurement data comparison between the two groups using t test or calibration of the t test and inspection level of alpha is0.05.ResultsThe general datas of the three groups of patients have no statistical significance (P>0.05).The MAP and HR at T3and T4significantly increased compared with that at To in the group C(P<0.05). The difference among three groups of MAP, HR at To was not statistically significant (P>0.05). In the group D2and D2,the MAP and HR at T3and T4significantly decreased compared with group C(P<0.05). In the D1group, MAP was elevated compared with D2group (P<0.05), and the difference of HR was not statistically significant (P>0.05).The plasma AD and NA concentration of group C at T4was increased compared with To,(P<0.05). Three plasma AD and NA concentration at To, the difference was not statistically significant (P>0.05). Compared with group C, the plasma AD and NA concentrations of group D1and D2were decreased in T4(P<0.05). The difference of the plasma AD and NA concentration of group D1and D2was not statistically significant (P>0.05).Conclusion1. Intravenous infusion of dexmedetomidine before induction can inhibit the secretion and release of the catecholamine. It can also effectively inhibit the intubation stress response, which will help to maintain hemodynamic stability during the intubation period.2. Intravenous infusion of0.75pg/kg dexmedetomidine in10minutes, the clinical effact on attenuation stress responses to tracheal intubation is better than the doses of0.5μg/kg. |
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