***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 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 Background : The present study aim ed to assess the efficacy and safety of thoracic paravertebral regional anesthesia ( TPVBRA ) in patients with breast cancer surgery . Methods : In total , 72 patients undergoing breast cancer surgery were r and omly divided into an intervention group and a control group ; each group contained 36 subjects . Both groups received TPVBRA with 20 mL 0.25 % bupivacaine . In addition , subjects in the intervention group also received an additional 1 & mgr;g/kg dexmedetomidine .  Heart rate ( HR ) , systolic blood pressure ( SBP ) , diastolic blood pressure ( DBP ) , pain intensity ( measured by visual analogue scale , VAS ) , and analgesic consumption were assessed ; adverse events were also recorded . Results : Significant differences were observed in HR ( P < .05 ) , SBP ( P < .05 ) , and DBP ( P < .05 ) at the 30-minute point during surgery between the 2 groups . In addition , the time of the first administration of analgesia ( P = .043 ) and the mean consumption of analgesic agents ( P = .035 ) in the intervention group were much better than those in the control group . However , no significant differences in HR or VAS were found at any time point after surgery ( P > .05 ) . Furthermore , similar adverse events were detected in both groups ( P > .05 ) . Conclusion : The results of this study showed that TPVBRA combined with bupivacaine and dexmedetomidine can enhance the duration and quality of analgesia without serious adverse events OBJECTIVE The goals of this study were to examine agreement and estimate differences in sensitivity between pain assessment scales . DESIGN  Multiple simultaneous pain assessment s by patients in acute pain after oral surgery were used to compare a four-category verbal rating scale ( VRS-4 ) and an 11-point numeric rating scale ( NRS-11 ) with a 100-mm visual analog scale ( VAS ) . The sensitivity of the scales ( i.e. , their ability [ power ] to detect differences between treatments ) was compared in a simulation model by sampling from true pairs of observations using varying treatment differences of predetermined size . RESULTS There was considerable variability in VAS scores within each VRS-4 or NRS-11 category both between patients and for repeated measures from the same patient . Simulation experiments showed that the VAS was systematic ally more powerful than the VRS-4 in all simulations performed . The sensitivity of the VAS and NRS-11 was approximately equal . CONCLUSIONS In this acute pain model , the VRS-4 was less sensitive than the VAS . The simulation results demonstrated similar sensitivity of the NRS-11 and VAS when comparing acute postoperative pain intensity . The choice between the VAS and NRS-11 can thus be based on subjective preferences BACKGROUND Dexmedetomidine is an α-2-receptor agonist which might be used as an additive to local anaesthetics for various regional anaesthetic techniques . We therefore design ed this prospect i ve , double-blinded , controlled volunteer study to investigate the effects of dexmedetomidine as an adjuvant to ropivacaine on peripheral nerve block . METHODS  Ultrasound-guided ulnar nerve block ( UNB ) was performed in 36 volunteers with either 3 ml ropivacaine 0.75 % ( R ) , 3 ml ropivacaine 0.75 % plus 20 µg dexmedetomidine ( RpD ) , or 3 ml ropivacaine 0.75 % plus systemic 20 µg dexmedetomidine ( RsD ) .  UNB-related sensory and motor scores were evaluated . RESULTS Sensory onset time of UNB was not different between the study groups , whereas motor onset time was significantly faster in Group RpD when compared with the other study groups [ mean ( sd ) ] [ 21 ( 15 ) vs 43 ( 25 ) min in Group RsD and 47 ( 36 ) min in Group R , P<0.05 Group RpD vs other groups ] . The duration of sensory block was 350 ( 54 ) min in Group R , 555 ( 118 ) min in Group RpD , and 395 ( 40 ) min in Group RsD ( P<0.01 Group RpD vs other groups , P<0.05 Group RsD vs Group R ) . Motor block duration was similar to the duration of sensory block . CONCLUSIONS A profound prolongation of UNB of ∼60 % was detected with perineural dexmedetomidine when added to 0.75 % ropivacaine . The systemic administration of 20 µg dexmedetomidine result ed in a prolongation of ∼10 % during UNB with 0.75 % ropivacaine . Eudra-CT No. : 2012 - 000030 - 19 Various analgesic modalities have been tried to prolong the duration and to improve the quality of postoperative analgesia for the early rehabilitation and discharge from hospital after nephrectomy . Using local anaesthetic along with perineural steroids as adjuvant may prove promising for peripheral nerve block , especially paravertebral block ( PVB ) . This article aims to assess the efficacy of dexamethasone with bupivacaine as adjuvant for single bolus injection of thoracic PVB in patients undergoing elective nephrectomy . Sixty patients of American Society of Anesthesiologists physical status I and II were r and omly assigned to 2 groups of 30 patients each . Group D patients received 8 mg ( 2 mL ) of dexamethasone mixed to 18 mL of 0.25 % bupivacaine , whereas patients in group B received 18 mL of 0.25 % bupivacaine and 2 mL of 0.9 % saline as placebo to make a total volume of 20 mL infiltrated in PVB . Degree of analgesia achieved and duration of analgesia were recorded in each group along with total dose requirement of rescue analgesic and side effects in first 24 hours postoperatively . Group D patients with dexamethasone  had VAS score of 0–3 after 09 minutes of block up to 610.48 ± 12.24 minutes and after 16 minutes up to 402.34 ± 28.12 minutes in another group B patient , respectively . The total dose of intravenous fentanyl  in the first 24 hours postoperatively in group D was 98.6 ± 14.14 & mgr;g as compared with 147.6 ± 18.22 & mgr;g in group B. No other significant side effects were noted except for nausea and vomiting in 5 patients of placebo group . Dexamethasone , along with bupivacaine as adjunct for thoracic PVB , helps in improving the quality and enhancing the postoperative analgesia duration in patients undergoing nephrectomy Background and Objectives Research suggests that the addition of dexmedetomidine to local anesthetics can prolong peripheral nerve blocks ; however , clinical safety data are limited , and interscalene blocks have not been studied . The present study was design ed to test the hypothesis that dexmedetomidine added to ropivacaine would safely enhance the duration of analgesia without adverse effects when compared with ropivacaine alone . Methods We conducted a single-center , prospect i ve , r and omized , triple-blind , controlled trial of 62 patients undergoing elective shoulder surgery under general anesthesia with an interscalene block . Patients underwent ultrasound-guided interscalene blocks using either 12 mL of 0.5 % ropivacaine or 0.5 % ropivacaine plus 150-µg dexmedetomidine . The primary outcomes were self-reported duration of the nerve block and safety assessment ( adverse effects and neurological sequelae ) . Data were analyzed in a blinded fashion . Results The median duration of the nerve block was 18 hours ( 95 % confidence interval , 18–20 ) in the dexmedetomidine group and 14 hours ( 95 % confidence interval , 14–16 ) in the ropivacaine group ( P = 0.0001 ) . Dexmedetomidine also lowered pain scores for the first 14 hours postoperatively and significantly hastened the time to sensory ( P = 0.04 ) and motor ( P = 0.002 ) block onset . Dexmedetomidine  lowered heart rate but blood pressures were stable . Plasma levels of ropivacaine were not different between groups , and plasma dexmedetomidine levels were relatively low . There were no adverse events or neurological sequelae . Conclusions Dexmedetomidine added to ropivacaine for interscalene blocks increased the duration of the nerve block and improved postoperative pain . These additional efficacy and safety data should encourage further study of peripheral perineural dexmedetomidine in humans Background This study determined the responses to increasing plasma concentrations of dexmedetomidine in humans . Methods Ten healthy men ( 20–27 yr ) provided informed consent and were monitored ( underwent electrocardiography , measured arterial , central venous [ CVP ] and pulmonary artery [ PAP ] pressures , cardiac output , oxygen saturation , end-tidal carbon dioxide [ ETCO2 ] , respiration , blood gas , and catecholamines ) . Hemodynamic measurements , blood sampling , and psychometric , cold pressor , and baroreflex tests were performed at rest and during sequential 40-min intravenous target infusions of dexmedetomidine ( 0.5 , 0.8 , 1.2 , 2.0 , 3.2 , 5.0 , and 8.0 ng/ml ; baroreflex testing only at 0.5 and 0.8 ng/ml ) . Results The initial dose of dexmedetomidine decreased catecholamines 45–76 % and eliminated the norepinephrine increase that was seen during the cold pressor test . Catecholamine suppression persisted in subsequent infusions . The first two doses of dexmedetomidine increased sedation 38 and 65 % , and lowered mean arterial pressure by 13 % , but did not change central venous pressure or pulmonary artery pressure . Subsequent higher doses increased sedation , all pressures , and calculated vascular resistance , and result ed in significant decreases in heart rate , cardiac output , and stroke volume . Recall and recognition decreased at a dose of more than 0.7 ng/ml . The pain rating and mean arterial pressure increase to cold pressor test progressively diminished as the dexmedetomidine dose increased . The baroreflex 
    Output:
    
DEX also increased the odds of hypotension by odds ratio ( OR ) 4.40 ( 95 % CI [ 1.37 , 14.17 ] , P = .01 ) ; however , there was no statistically significant difference for intraoperative fentanyl consumption and the incidence of the bradycardia .
Conclusions DEX combined with LAs in PVB significantly improved postoperative pain scores , prolonged the duration of analgesia , reduced postoperative analgesic consumption , and increased the odds of hypotension .