ABSTRACT
Objective To study the median effective doses (ED50) of dexmedetomidine to induce adequate sedation in elderly patients undergoing epidural anaesthesia. Methods Seventy-five elderly patients undergoing lower extremity operation under epidural anesthesia were selected, and the patients were divided into 5 groups according to the random digits table method with 15 cases each: D1 group (dexmedetomidine 0.2 μg/kg), D2 group (dexmedetomidine 0.4 μg/kg), D3 group (dexmedetomidine 0.6 μg/kg), D4 group (dexmedetomidine 0.8μg/kg) and D5 group (dexmedetomidine 1.0μg/kg). After 20 min of dexmedetomidine injection, adequate sedation was defines as observer′s assessment of alertness/sedation score (OAA/S score) ≤ 3 scores. The ED50 and 95% effective dose (ED95) of dexmedetomidine and 95% CI in elderly patients undergoing epidural anaesthesia were calculated by probit regression method. The changes of mean arterial pressure (MAP), heart rate, pulse oxygen saturation (SpO2) and OAA/S score among 5 groups were compared. The incidences of adverse effects such as hypotension, bradycardia, hypoxemia and excessive sedation were compared. Results The ED50 in elderly patients was 0.36 μg/kg (95% CI 0.27 - 0.44 μg/kg); the ED95 was 0.94 μg/kg (95% CI 0.71 - 1.62 μg/kg). After dexmedetomidine injection, the MBP, heart rate, SpO2 and OAA/S scores in 5 groups were decreased, but in the D4 group and D5 group the decreases were more significant. The incidences of hypotension, bradycardia and excessive sedation in D1 group, D2 group and D3 group were significantly lower than those in D4 group and D5 group:2/15, 5/15 and 8/15 vs. 14/15 and 15/15;1/15, 6/15, 7/15 vs. 13/15 and 14/15;0, 0 and 1/15 vs. 5/15 and 7/15, the incidences of hypoxemia in D1 group, D2 group and D3 group were significantly lower than those in D5 group: 0, 0 and 0 vs. 3/15 and 4/15, and there were statistical differences (P0.05). Conclusions The ED50 of dexmedetomidine in elderly patients undergoing epidural anaesthesia is 0.36μg/kg, (CI 0.27-0.44μg/kg). The incidences of adverse effects are increased when single-dose dexmedetomidine is more than 0.8μg/kg.
ABSTRACT
Objective To determine the 50%effective dose (ED 50) of dexmedetomidine for sedation in the brachial plexus block, so as to provide reference for clinical. Methods Twenty-three patients underwent the brachial plexus block using an ultrasound guided technique. After blocked for 30 min, the dexmedetomidine was infused by a intravenous continuous pump,and an observer' s assessment of alertness/sedation score (OAA/S) and auditory evoked potential index (AEPI) were used for monitoring the depth of sedation. The dexmedetomidine was adjusted according to the response of the previous patient using a up-and-down sequential method until the sequential response curve appeared seven fold points. The initial dexmedetomidine of the first patient was 1μg/kg. Each time the dosage increased/decreased by 0.1μg/kg. The OAA/S score of no more than 3 was defined an effective sedation. Results The ED50 of dexmedetomidine for sedation was 0.78μg/kg (95%CI 0.66-0.86μg/kg). The AAI was positively correlated to the OAA/S score, and linear regression equation was Y=-1.43+0.109 X, R2=0.919. Conclusion The ED50 of dexmedetomidine for sedation in the brachial plexus block is 0.78μg/kg (95%CI 0.66-0.86μg/kg).
ABSTRACT
Objective To investigate the effects of butorphanol pretreatment on myocardial injury induced by limb ischemia/reperfusion.Methods Forty patients with distal lower extremity orthopedic surgery (ASA Ⅰ or Ⅱ) were divided into two groups by random digits table method with 20 cases each:butorphanol group and control group.Epidural anesthesia was selected in all patients.In butorphanol group,patients were given butorphanol 0.04 mg/kg intravenously 15 min before tourniquet.In control group,equal volume of normal saline was infused at the same time.Blood samples were taken from jugular vein before tourniquet (T0),then 5 min(T1),2 h (T2),6 h (T3),12 h (T4) and 24 h (T5) after the second reperfusion of tourniquet.The serum creatine kinase isoenzyme MB (CK-MB),cardiac troponin Ⅰ (cTnI),tumor necrosis factor-α (TNF-α) and malondialdehyde (MDA) levels were determined.Results Compared with those at T0,the serum C K-MB levels were increased at T2-T5,the serum cTnI,MDA,TNF-α levels were increased at T1-T5 in control group,and there were significant differences (P ＜ 0.05).Compared with those at T0,the serum CK-MB levels were increased at T3,T4,the serum TNF-α levels were increased at T1-T3,the serum cTnI levels were increased at T1-T5 in butorphanol group,and there were significant differences (P ＜ 0.05).Compared with those in control group,the serum CK-MB levels were decreased at T2-T5 [(20.2 ± 5.0) U/L vs.(35.3 ±6.8) U/L,(32.3 ±3.7) U/L vs.(48.6 ±8.5) U/L,(29.5 ±5.4) U/L vs.(51.5 ±8.0) U/L,(22.2 ±4.8) U/L vs.(33.7 ±6.7) U/L],the serum cTnI,TNF-α levels were decreased at T1-T5 [(0.158 ± 0.016) μg/L vs.(0.278 ±0.021) μg/L,(0.169 ±0.036) μg/L vs.(0.332 ± 0.062) μg/L,(0.357 ±0.049) μg/L vs.(0.623 ±0.083) μg/L,(0.178 ±0.045) μg/L vs.(0.383 ±0.059) μg/L,(0.138 ±0.016) μg/L vs.(0.263 ±0.023) μg/L; (1.63 ±0.13) μg/L vs.(2.12 ±0.08) μg/L,(1.69 ± 0.08) μ g/L vs.(2.28 ± 0.09) μ g/L,(1.63 ± 0.09) μ g/L vs.(2.25 ± 0.07) μ g/L,(1.23 ± 0.14) μμg/Lvs.(1.93±0.12) μg/L,(1.13±0.15) μμg/Lvs.(1.79±0.07) μμg/L],theserumMDAlevelswere decreased at T1-T4 [(4.82 ±0.53) nmol/L vs.(6.68 ±0.67) nmol/L,(4.99 ±0.61) nmol/L vs.(7.59 ±0.72) nmol/L,(5.02 ±0.43) nmol/L vs.(7.54 ±0.63) nmol/L,(4.52 ±0.55) nmol/L vs.(6.52 ±0.47) nmol/L] in butorphanol group,and there were significant differences (P ＜0.05).Conclusion Butorphanol pretreatment can improve the serum CK-MB,cTnI levels,and has a protective role for myocardial injury induced by limb ischemia/reperfusion.