Preliminery Study Of Clinical Application For Dexmedetomidine

Dexmedetomidine is a potent and highly selective α2-adrenoreceptor agonist, which offers remarkable pharmacological properties including sedation, anxiolysis, and analgesia with the unique characteristic to cause no respiratory depression. Dexmedetomidine was initially only utilized for continuous infusion for sedation/analgesia in the intensive care unit (ICU). In recent years, Dexmedetomidine has emerged as an affective therapeutic drug in a wide range of anesthetic management, promising large benefits in the perioperative use, due to its benificial for hemodynamic stability.2009listed in our use, viewing of the current uncertain clinical anesthesia application of safety factors, we made clinical and basic research and hope for a more in-depth understanding of the influence of physiological function in clinical use of dexmedetomidine. In addition, clinical safe applications could be provided.1. A study of dexmedetomidine for sedation during awake fiberoptic intubation.ObjectiveTo evaluate the efficacy and safety of dexmedetomidine (DEX) for sedation during awake fiberoptic intubation (AFOI) under local anesthesia.MethodsForty patients, ASAI-Ⅱ, were randomly divided into two groups, group dexmedetomidine(D) and group fentanyl(F),20patients in each. Patients in Group D received dexmedetomidine1μg/kg-1and patients in Group F received fentanyl1μg/kg-1as bolus over a10minute period before intubation, then AFOI. Recorded the room entrance(T1), the end of drug infusion immediately(T2), and the intubation success instantly(T3) hemodynamic parameters:systolic (SBP), diastolic blood pressures (DBP), heart rate (HR), pulse oximetry(SPO2), bispectral index(BIS), and Ramsay sedation score. Intubation time, intubation tolerance, and satisfaction rate were recorded also.ResultsAll patients present HR decreased after given dexmedetomidine and there is more significant difference within groups (P<0.05). Group D HR, SBP was significantly lower than Group F at T2, T3(P<0.05). Group D BIS below Group F, and Ramsay score was higher than Group F at T2, T3(P<0.05). Need to deal with the HR, BP, SPO2decreased were not occurred. Patients in Group D were significantly calmer and more cooperative during AFOI. They also were more satisfied with the AFOI than were Group F patients.ConclusionsDexmedetomidine was demonstrated to be an efficacious and safe adjuvant for procedural sedation during awake fiberoptic intubation with respiratory inhibition and hemodynamic stability.2. baroreflex changes during dexmedetomidine intravenous infusionObjectiveTo learn whether dexmedetomidine can impact on baroreflex by baroreflex sensitivity testing during dexmedetomidine intravenous infusion, providing reference for clinical medication.MethodsForty-five patients, ASAI-Ⅱ, were randomly divided into three groups,15patients in each. Group LD:loading dexmedetomidine0.5μg/kg for10min and maintenance0.2μg/kg.h-1. Group MD:loading dexmedetomidine1μg/kg for10min and maintenance0.5μg/kg.h-1. Group C:continuous infusion of0.9%saline. Recorded the room entrance(T1), the steady-state:after dexmedetomidine infusion for30min(T2) hemodynamic parameters:systolic (SBP), diastolic blood pressures (DBP), heart rate (HR), pulse oxygen saturation(SPO2), bispectral index(BIS). A modified Oxford pharmacologic technique was used for evaluating baroreflex sensitivity. Recorded HR, SBP at intervals of the30s. Calculated HR variation(⊿HR), SBP variation(⊿SAP), and took the⊿HR/⊿SAP as baroreflex sensitivity index.ResultsTo the comparision of the three groups at T2, HR, SBP of group LD, group MD were lower than group C (P<0.05). Decline in SBP caused by sodium nitroprusside injection in group LD and group MD was lower compared with group C (P<0.05) Compared with group C, the BRS of the group LD, group MD presented no significant difference. But in the sequence of increased blood pressure, the BRS present a upward trend with dexemedtomidine dose rights, while a downward trend in the sequence of decreased blood pressure.ConclusionsDuring dexemedtomidine intravenous infusion, the baroreflex sensitivity is maintained, though it can cause blood pressure to drop.In summary, dexemedetonidine can cause sympathetic inhibition by exciting central α2-AR. On the one hand, these drugs weaken the reaction of adrenergic nerve response to noxious stimuli. On the other hand, fluctuations in blood pressure can be buffered by the baroreflex. This combined effect is the possible mechanism of stable perioperative hemodynamic, and to reduce the sympathetic activation of surgical or anesthesia stimulation. But for various reasons lead to hypotention, dexemedetomidine is likely to cause adverse cardiovascular events.