sábado, 9 de noviembre de 2013

Sedación con dexmedetomidina/Dexmedetomidine for sedation

Dosis óptima de dexmedetomidina para sedación durante raquianestesia  
Optimal dose of dexmedetomidine for sedation during spinal anesthesia.
Ok HG, Baek SH, Baik SW, Kim HK, Shin SW, Kim KH.
Department of Anesthesia and Pain Medicine, Pusan National University College of Medicine, Yangsan, Korea.
Korean J Anesthesiol. 2013 May;64(5):426-31. doi: 10.4097/kjae.2013.64.5.426. Epub 2013 
BACKGROUND:Sedation in spinal anesthesia can reduce patient's anxiety and discomfort. Dexmedetomidine has a sedative, hypnotic, analgesic, and minimal respiratory depression effect. However, use of the dexmedetomidine is associated with prolonged recovery. This study was designed to investigate the optimal dose of intravenous dexmedetomidine for proper sedation with minimal recovery time in spinal anesthesia. METHODS: One hundred twenty eight patients, aged 20-70 years (58.8 ± 0.7), were recruited. After performing the spinal anesthesia with hyperbaric bupivacaine (13 mg), a loading dose of dexmedetomidine (1 µg/kg) was administered for 10 min, followed by the maintenance infusion of the following: Group A (n = 33; normal saline), Group B (n = 35; dexmedetomidine 0.2 µg/kg/hr), and Group C (n = 39; dexmedetomidine 0.4 µg/kg/hr). Heart rate, blood pressure, and the bispectral index score (BIS) were recorded during the operation. In the recovery room, modified aldrete score (MAS) was measured. RESULTS: There were no significant differences in mean blood pressure and heart rate among the three groups. BIS was not significantly different among the three groups from baseline to 60 min after the infusion of dexmedetomidine. BIS were significantly increased in Group A after 70 and 80 min, and Group A and B after 90, 100, 110 min of dexmedetomidine infusion (P < 0.05). MAS was higher in Group A as compared to Group B and C, within 30 min after admission in the recovery room (P < 0.05). CONCLUSIONS: The loading dose (1 µg/kg/10 min) of dexmedetomidine was sufficient for surgery of less than 60 min. Dexmedetomidine infusion followed by maintenance dose (0.2 µg/kg/hr) was sufficient for surgery within 90 min.
KEYWORDS: Dexmedetomidine, Sedation, Spinal anesthesia 

Dexmedetomidina para sedación de pacientes de cirugía electiva bajo anestesia raquídea      
Dexmedetomidine for sedation of patients undergoing elective surgery under regional anesthesia.
Song J, Kim WM, Lee SH, Yoon MH.
Department of Anesthesiology and Pain Medicine, Chonnam National University Hospital, Gwangju, Korea.
Korean J Anesthesiol. 2013 Sep;65(3):203-8. doi: 10.4097/kjae.2013.65.3.203. Epub 2013 Sep 25.
BACKGROUND:Dexmedetomidine may be useful as a sedative agent. However, it has been reported that dexmedetomidine decreases systemic blood pressure, heart rate, and cardiac output in a dose-dependent manner. The purpose of this study was to determine the appropriate dose of intravenously administered dexmedetomidine for sedation. METHODS: Forty-five American Society of Anesthesiologists physical status I-II patients under spinal anesthesia received dexmedetomidine 1 µg/kg intravenously as a loading dose. The patients were randomly allocated to one of three groups for maintenance dose: Group A (0.25 µg/kg/hr), Group B (0.50 µg/kg/hr), and Group C (0.75 µg/kg/hr). The hemodynamic variables and the Ramsay Sedation Scale (RSS) score were recorded for all patients. The numbers of patients who developed hypotension, bradycardia, or inadequate sedation necessitating further drug treatment were also recorded.
RESULTS: Systolic blood pressure, heart rate, and SpO2 were decreased, and RSS score was increased significantly at both 20 min and 40 min after injection of dexmedetomidine in the three study groups compared to baseline, without significant differences between the groups. The prevalence of hypotension, but not that of bradycardia or adjunctive midazolam administration, exhibited a positive correlation with the dose of dexmedetomidine. CONCLUSIONS: Intravenous injection of dexmedetomidine 1 µg/kg followed by continuous administration at infusion rates of 0.25, 0.50, or 0.75 µg/kg/hr produced adequate levels of sedation. However, there was a tendency for the incidence of hypotension to increase as the dose increased. To minimize the risk of hemodynamic instability, a dose of 0.25 µg/kg/hr may be the most appropriate for continuous administration of dexmedetomidine.
KEYWORDS: Continuous dose, Dexmedetomidine, Regional anesthesia, Sedation

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