***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND : This study evaluated the motor and sensory block duration s and the postoperative analgesic effects of adding dexmedetomidine to levobupivacaine for sub-Tenon ’s block anesthesia in patients undergoing vitreoretinal surgery . Motor and sensory block duration s were considered as a primary end point . METHODS : Sixty ASA physical status I to III patients subjected to vitreoretinal surgery under sub-Tenon ’s block anesthesia were r and omly divided equally into 2 groups , depending on the local anesthesia solution used , to receive 4 mL of 0.75 % levobupivacaine plus 15 IU hyaluronidase diluted with 1 mL normal saline ( group L ) or 4 mL of 0.75 % levobupivacaine plus 15 IU hyaluronidase and 20 & mgr;g dexmedetomidine diluted with 1 mL normal saline ( group LD ) . The total volume of the local anesthesia solution used was 5 mL. Motor block and sensory block duration s were evaluated until the return of normal motor and sensory functions . The sedation level was assessed during the surgery period and 24 hours postoperatively , together with the degree of postoperative pain . The total diclofenac consumption ( milligrams ) and the number of patients ( % ) who required tramadol were recorded . The sleep quality of the first postoperative night was assessed using the Consensus Sleep Diary . RESULTS : Dexmedetomidine provided significantly longer motor block duration ( 371.90 ± 48.10 vs 264.13 ± 41.48 minutes , P = 0.001 ) and significantly longer sensory block duration ( 499.10 ± 51.76 vs 344.33 ± 45.46 minutes , P = 0.001 ) compared with levobupivacaine alone . Furthermore , the patients in the dexmedetomidine group achieved significantly ( P < 0.0001 ) greater levels of sedation during the surgery period and for 12 hours postoperatively together with significantly ( P < 0.0001 ) lower values of verbal numeric rating scale of pain between the periods from 4 to 12 hours postoperatively compared with the patients in the levobupivacaine group . There was significantly ( P = 0.001 ) less diclofenac consumed ( mg ) in the dexmedetomidine group . The patients in the dexmedetomidine group reported significantly higher rates of good sleep quality on the first postoperative night ( 70 % ) compared with those in the levobupivacaine group ( 30 % ; P < 0.0001 ) . CONCLUSIONS : For patients undergoing vitreoretinal surgery , adding 20 & mgr;g of dexmedetomidine to levobupivacaine for sub-Tenon ’s block anesthesia in vitreoretinal surgery extended the motor and sensory block duration s and provided more effective postoperative analgesia with improvement in the sleep quality in the first postoperative night compared with levobupivacaine alone Background Apha-2 agonists are combined with local anesthetics to extend the duration of regional anesthesia . We evaluated the effect of combining dexmedetomidine with levobupivacine with respect to duration of motor and sensory block and duration of analgesia . Methods Sixty patients scheduled for elective forearm and h and surgery were divided into two equal groups in a r and omized double blind fashion . The patients received brachial plexus block via supraclavicular route with the help of nerve stimulator . In group L ( n=30 ) 35cc of levobupivacaine with 1ml of isotonic saline and in group LD ( n=30 ) 35cc of levobupivacine with 1 ml of ( 100 microgram ) of dexmedetomidine was given . Duration of motor and sensory block and time to first rescue analgesia were recorded . Data analysis was done by SPSS version 16.0 [ SPSS Inc ILLINOIS , USA , 2008 ] . Categorical variables were analyzed using Pearson”s Chi-square test . Normally distributed numerical variables were analyzed using unpaired “ t ” test . Skewed numerical variables within the group were analyzed using Man-Whitney “ U ” test . All tests were two tailed . Statistical significance was defined as P<0.05 . Results Sensory and motor block duration s were longer in group LD as compared to L ( P<0.01 ) . Duration of analgesia was significantly longer in group LD as compared to group L ( p<0.05 ) . Conclusion Dexmedetomidine added to levobupivacaine in supraclavicular brachial plexus block prolongs the duration of block and the duration of postoperative analgesia Background : Perineural and IV dexmedetomidine have each been suggested to prolong the duration of analgesia when administered in conjunction with peripheral nerve blocks . In the first r and omized , triple-masked , placebo-controlled trial to date , the authors aim ed to define and compare the efficacy of perineural and IV dexmedetomidine in prolonging the analgesic duration of single-injection interscalene brachial plexus block ( ISB ) for outpatient shoulder surgery . Methods : Ninety-nine patients were r and omized to receive ISB using 15 ml ropivacaine , 0.5 % , with 0.5 & mgr;g/kg dexmedetomidine administered perineurally ( DexP group ) , intravenously ( DexIV group ) , or none ( control group ) . The authors sequentially tested the joint hypothesis that dexmedetomidine prolongs the duration of analgesia and reduces the 24-h cumulative postoperative morphine consumption . Motor blockade , pain severity , hemodynamic variations , opioid-related side effects , postoperative neurologic symptoms , and patient satisfaction were also evaluated . Results : Ninety-nine patients were analyzed . The duration of analgesia was 10.9 h ( 10.0 to 11.8 h ) and 9.8 h ( 9.0 to 10.6 h ) for the DexP and DexIV groups , respectively , compared with 6.7 h ( 5.6 to 7.8 ) for the control group ( P < 0.001 ) . Dexmedetomidine also reduced the 24-h cumulative morphine consumption to 63.9 mg ( 58.8 to 69.0 mg ) and 66.2 mg ( 60.6 to 71.8 mg ) for the DexP and DexIV groups , respectively , compared with 81.9 mg ( 75.0 to 88.9 mg ) for the control group ( P < 0.001 ) . DexIV was noninferior to DexP for these outcomes . Both dexmedetomidine routes reduced the pain and opioid consumption up to 8 h postoperatively and did not prolong the duration of motor blockade . Conclusion : Both perineural and IV dexmedetomidine can effectively prolong the ISB analgesic duration and reduce the opioid consumption without prolonging motor blockade Aims and Objectives : Supplementation of dexmedetomidine produces a dose-dependent sedation , anxiolysis and analgesia without respiratory depression . This study was conducted to evaluate the possible effect of dexmedetomidine as an adjuvant to levobupivacaine for supraclavicular brachial plexus block in upper limb surgery . Setting s and Design : Tertiary care institute , Department of Anaesthesiology and Intensive Care , a placebo-controlled study . Material s and Methods : After obtaining Ethical Committee approval , a r and omized , double-blind , placebo-controlled study was conducted on sixty American Society of Anesthesiologists physical status I and II patients in the age group of 18–60 years , divided r and omly into two groups , Group I received 30 ml of 0.5 % levobupivacaine with 1 ml of isotonic sodium chloride solution and Group II received 30 ml of 0.5 % levobupivacaine and 1 ml ( 100 mcg ) of dexmedetomidine for supraclavicular brachial plexus block . The onset and duration of sensory and motor blockade , duration of analgesia ( DOA ) and any adverse effects were noted . At the end of the study , data were compiled and analyzed using appropriate statistical tests . The value of P < 0.05 was considered significant . Results : Demographic profile was comparable in both the groups . The time to onset of sensory and motor block was 10.54 ± 2.333 min and 12.21 ± 2.529 min in Group I while it was 3.24 ± 0.951 min and 2.83 ± 1.197 min in Group II , respectively . The duration of sensory and motor block was 7.79 ± 2.007 h and 9.18 ± 1.701 h in Group I , and it was 16.31 ± 2.606 h and 17.52 ± 2.098 h in Group II , respectively . The DOA was 678.68 ± 20.492 min in Group I and 1273.79 ± 83.139 min in Group II . On statistical comparison , these values were highly significant ( P < 0.001 ) . Side effects such as nausea , vomiting , hypoxemia , pruritis , or urinary retention were not observed in either of the groups . Conclusion : Dexmedetomidine shortens the onset time for sensory and motor block significantly and prolongs DOA as well when used with levobupivacaine for supraclavicular brachial plexus block , without increasing the incidence of any adverse effects BACKGROUND There is little systematic research on the efficacy and tolerability of the addition of adjunctive analgesic agents in paravertebral analgesia . The addition of adjunctive analgesics , such as fentanyl and clonidine , to local anesthetics has been shown to enhance the quality and duration of sensory neural blockades , and decrease the dose of local anesthetic and supplemental analgesia . OBJECTIVES Investigation of the safety and the analgesic efficacy of adding 1 μg/kg dexmedetomidine to bupivacaine 0.25 % in thoracic paravertebral blocks ( PVB ) in patients undergoing modified radical mastectomy . STUDY DESIGN A r and omized , double-blind trial . SETTING Academic medical center . METHODS Sixty American Society of Anesthesiologists physical status -I - III patients were r and omly assigned to receive thoracicPVB with either 20 mL of bupivacaine 0.25 % ( Group B , n = 30 ) , or 20 mL of bupivacaine 0.25 % + 1 μg/kg dexmedetomidine ( Group BD , n= 30 ) . Assessment parameters included hemodynamics , sedation score , pain severity , time of first analgesics request , total analgesic consumption , and side effects in the first 48 hours . RESULTS There was a significant reduction in pulse rate and diastolic blood pressure starting at 30 minutes in both groups , but more evidence d in group BD ( P < 0.001 ) . Intraoperative Systolic blood pressure showed a significant reduction at 30 minutes in both groups ( P < 0.001 ) then returned to baseline level at 120 minutes in both groups . There was a significant increase in pulse rate starting 2 hours postoperative until 48 hours postoperatively in group B but only after 12 hours until 48 hours in group BD ( P < 0.001 ) . The time of the first rescue analgesic requirement was significantly prolonged in the group BD ( 8.16 ± 42 hours ) in comparison to group B ( 6.48 ± 5.24 hours ) ( P = 0.04 ) . The mean total consumption of intravenous tramadol rescue analgesia in the postanesthesia care unit in the firtst 48 hours postoperatively was significantly decreased in group BD ( 150.19 ± 76.98 mg ) compared to group B ( 194.44 ± 63.91 mg ) ( P = 0.03 ) . No significant serious adverse effects were recorded during the study . LIMITATIONS This study is limited by its sample size . CONCLUSION The addition of dexmedetomidine 1 μg/kg to bupivacaine 0.25 % in thoracic PVB in patients undergoing modified radical mastectomy improves the quality and the duration of analgesia and also provides an analgesic sparing effect with no serious side effects This week , a series of four articles considers the place of the r and omised controlled trial as we approach the second century of experience with the concept . Its basic principle is genuine uncertainty as to which treatment arm of the trial it would be in a patient 's best interests to enter . This is not necessarily an easy concept to transmit , Background and Aims : Different additives have been used to prolong brachial plexus block . We evaluated the effect of adding dexmedetomidine to ropivacaine for supraclavicular brachial plexus blockade . The primary endpoints were the onset and duration of sensory and motor block and duration of analgesia . Material s and Methods : A total of 84 patients ( 20 - 50 years ) posted for elective forearm and h and surgery under supraclavicular brachial plexus block were divided into two equal groups ( Group R and RD ) in a r and omized , double-blind fashion . In group RD ( n = 42 ) 30 ml 0. 
    Output:
    
This meta- analysis demonstrated that DEX in combination with local anaesthetics increases postoperative analgesia for around 5 h. However , there are higher risks of intraoperative hypotension and bradycardia .
Initial evidence suggests no difference in the duration of analgesia associated with systemic or perineural DEX .