***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 
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    ***EXAMPLES*** 
    Input: Background : The α2-adrenoreceptor agonist , dexmedetomidine , provides excellent sedation with minimal cardiovascular instability or respiratory depression and may be a useful adjunct to facilitate smooth tracheal extubation . Material s and Methods : Fifty American Society of Anesthesiologists grade I-II patients , aged 20 - 45 years , scheduled for elective general surgical , urological and gynecological surgeries were studied after r and omization into two groups . Group A and B , received an intravenous infusion of dexmedetomidine 0.75 mcg/kg or placebo respectively , over 15 minutes before anticipated time of end of surgery , in a double blind manner . Anesthesia techniques were st and ardized . Heart rate , systolic , diastolic , mean arterial pressures were recorded while starting injection , at 1 , 3 , 5 , 10 , 15 minutes after starting injection , during extubation , at 1 , 3 , 5 minutes after extubation , and thereafter every 5 minutes for 30 minutes . Quality of extubation was evaluated on a 5 point scale and postoperative sedation on a 6 point scale . Any event of laryngospasm , bronchospasm , desaturation , respiratory depression , vomiting , hypotension , undue sedation was noted . Results : Heart rate , systolic , diastolic , mean arterial pressures were significantly higher in group B ( P < 0.05 ) . Extubation quality score of majority of patients was 2 in group A and 3 in group B. Sedation score of most patients was 3 in group A and 2 in group B. Bradycardia and hypotension incidences were higher in group A. One patient in group A , two patients in group B had vomiting . No patient had any other side effects . Conclusion : Dexmedetomidine 0.75 mcg/kg administered 15 minutes before extubation , stabilizes hemodynamics and facilitates smooth extubation Emergence from general anesthesia can be associated with coughing , agitation , and hemodynamic disturbances .  Remifentanil may attenuate these responses . We have examined the effect of remifentanil on the hemodynamic response to the emergence from anesthesia and tracheal extubation . In a double-blind , r and omized trial , we enrolled 50 adult patients undergoing abdominal surgery .  All patients received a st and ard general anesthetic comprising propofol , atracurium and 1 % isoflurane with 50 % nitrous oxide in oxygen . At the end of surgery , a bolus dose of remifentanil 0.2 microgram/kg ( n = 25 ) or saline placebo ( n = 25 ) was given and tracheal extubation was performed when st and ard criteria were achieved . Arterial pressure and heart rate were measured non-invasively , immediately after tracheal extubation and then at 1-min intervals . Remifentanil attenuated the increase in both systolic and diastolic arterial pressure and heart rate after extubation compared to the control group . No differences in SpO2 , cough and laryngospasm were observed between two groups . Use of a low-dose remifentanil has clinical ly acceptable effect in blunting the cardiovascular changes induced by tracheal extubation Background Remifentanil and dexmedetomidine are well known to suppress airway reflexes during airway procedures . Smooth tracheal extubation is important after otologic surgery . The purpose of this study is to compare the effectiveness of dexmedetomidine or remifentanil infusion for producing smooth tracheal extubation in deeply anesthetized patients after otologic surgery . Methods Seventy-four ASA I-II adult patients ( 18 - 60 years old ) scheduled for elective otologic surgery were r and omly assigned to one of three groups : sevoflurane-remifentanil ( Group SR , n = 25 ) , sevoflurane-dexmedetomidine ( 0.5 μg/kg ) ( Group SD5 , n = 24 ) , or sevoflurane-dexmedetomidine ( 0.7 μg/kg ) ( Group SD7 , n = 25 ) . Remifentanil or dexmedetomidine were administered for 10 min at the end of surgery . The primary outcome was the rate of smooth extubation . Respiratory pattern , airway obstruction , hemodynamic and respiratory profiles , time to awake , rescue analgesics in the post-anesthesia care unit ( PACU ) , and postoperative nausea and vomiting ( PONV ) were also recorded . Results The rate of smooth tracheal extubation as defined 1 min post-extubation was the same for Groups SR and SD7 ( P > 0.05 ) , but the rate of smooth extubation was lower for Group SD5 than for the other two groups ( p < 0.05 ) . During extubation , the respiratory rate was lower in Group SR than in both dexmedetomidine groups ( p < 0.05 ) . The hemodynamic profiles at extubation were similar between groups ( p > 0.05 ) , but the mean arterial pressure and heart rate were higher in Group SR at 10 and 15 min after extubation ( p < 0.05 ) . The incidence of airway obstruction and time to awake were comparable for all groups ( p > 0.05 ) . The need for rescue analgesic in the PACU was more common in Group SR than in both dexmedetomidine groups ( P < 0.01 ) . Compared to Group SR , both dexmedetomidine groups had less PONV on postoperative day 1 ( p < 0.05 ) . Conclusion Combined with 1 MAC sevoflurane , dexmedetomidine 0.7 ug/kg and remifentanil provided similar rates for smooth tracheal extubation in spontaneously breathing , anesthetized adults .  Dexmedetomidine exhibited opioid-sparing effects postoperatively and was associated with less PONV than remifentanil BACKGROUND : Emergence from general anesthesia can be associated with coughing , agitation , and hemodynamic disturbances .  Remifentanil may attenuate these responses . METHODS : In a prospect i ve , double-blind , r and omized trial , we enrolled 60 adult patients undergoing nasal surgery using remifentanil-based anesthesia .  During the emergence phase , the remifentanil group had remifentanil reduced to one tenth of the maintenance rate , whereas the control group had remifentanil discontinued . RESULTS : Times to awakening and tracheal extubation were similar between the two groups . During emergence , the remifentanil group ( infusion rate 0.014 ± 0.011 & mgr;g · kg−1 · min−1 ) had a significantly lower incidence ( 40 % vs 80 % , P = 0.002 ) and less severe coughing compared with the control group , as well as a lower incidence of non purpose ful movement ( 3.3 % vs 30 % , P = 0.006 ) and slower heart rates . CONCLUSIONS : Low-dose remifentanil during emergence did not prolong wake-up but reduced the incidence and severity of coughing from the endotracheal tube Background Intraoperative dexmedetomidine may decrease postoperative emergence agitation in elderly patients due to its sedative effect . In this study , we evaluated the effect of adjuvant dexmedetomidine on smooth emergence from anaesthesia after orthopaedic surgery in elderly patients . Methods A total 115 patients ( ASA I – II , aged over 65 years ) were r and omly allocated into four groups . Anaesthesia was maintained with either sevoflurane or total intravenous anaesthesia ( TIVA ) comprising propofol and remifentanil . Patients were also administered either dexmedetomidine ( 0.4 μg kg−1 hr−1 ; SD and TD ) intraoperatively or normal saline ( SN or TN ) as a control . The bispectral index ( BIS ) score was maintained from 40–60 intraoperatively . All anaesthetics and dexmedetomidine were discontinued at surgical conclusion , and the recovery times ( duration s to a BIS = 60 , 70 , and 80 ; eye opening ; and extubation ) were measured . The mean arterial pressure , heart rate , Ricker ’s agitation-sedation scale ( RSAS ) , visual analogue scale ( VAS ) for pain , and incidences of emergence agitation and postoperative nausea and vomiting ( PONV ) were measured in the recovery room . Results Dexmedetomidine significantly decreased the RSAS score in the SD and TD groups , and a calm state postoperatively occurred more frequently in these groups than in the control groups . The heart rate and incidence of emergence agitation were lower in the dexmedetomidine groups . Recovery time was higher in the SD group than in the SN group , and no significant differences occurred between the TN and TD groups . The VAS score was lower in the SD group than in the SN group , and the PONV did not differ regardless of the use of dexmedetomidine . Conclusions Dexmedetomidine may be an effective intraoperative adjuvant for a reducing emergence agitation and smooth emergence from anaesthesia after orthopaedic surgery in elderly patients .Trial registration Current Controlled Trials NCT01851005 Extubation response can lead to cardiovascular and respiratory complications . Here , we aim ed to evaluate the effect of ropivacaine injected via the trans-cricothyroid membrane on the extubation response . This prospect i ve , double-blind , r and omized study included 70 patients classified as American Society of Anesthesiologists status I-II , who required general anesthesia with nasotracheal intubation for maxillary and m and ibular fracture surgery ; patients were divided into the ropivacaine ( 20 mg ) and dicaine ( 20 mg ) groups . Both groups were injected via the trans-cricothyroid membrane . Mean arterial pressure ( MAP ) , heart rate ( HR ) , and incidence and severity of cough were recorded during intubation and extubation . During intubation , there was no significant intergroup difference in MAP or HR and no occurrence of coughing ( P > 0.05 ) . During extubation , MAP and HR were significantly lower in the ropivacaine group than the dicaine group ( P < 0.05 ) . The proportion of patients with no reports of cough was significantly higher in the ropivacaine group than in dicaine group ( P < 0.05 ) . The number of patients with grade 1 or 2 cough was significantly higher in the dicaine group than that in the ropivacaine group ( P < 0.05 ) . There was no significant intergroup difference in the rate of postoperative complications ( P > 0.05 ) . These results suggest that the administration of ropivacaine via trans-cricothyroid membrane injection can effectively inhibit the extubation response BACKGROUND Emergence from anaesthesia and tracheal extubation can be associated with hyperdynamic circulatory responses . We examined the effects of maintaining a remifentanil infusion on recovery profiles such as coughing and cardiovascular responses after general anaesthesia . METHODS Forty patients undergoing endoscopic sinus surgery under general anaesthesia using total i.v . anaesthesia ( propofol and remifentanil )  were r and omly allocated to a control group ( n=20 ) or remifentanil group ( n=20 ) during emergence from anaesthesia . At the end of surgery , propofol was ceased and the infusion of remifentanil was stopped in the control group and maintained in the remifentanil group at a target organ concentration of 1.5 ng ml(-1 ) until extubation . Heart rate ( HR ) , mean arterial pressure ( MAP ) , and recovery profiles were measured and evaluated . RESULTS There was no significant difference in sex ratio , age , weight , height , time to eye opening , time to extubation , nausea , visual analogue scale , and time to discharge . Increases in HR and MAP occurred during emergence in the control group compared with baseline values . Increases in HR were attenuated in the remifentanil group and MAP decreased during recovery compared with baseline values . HR and MAP values were significantly higher in the control group [ 103 ( 23 ) beats min(-1 ) , 129 ( 17 ) mm Hg ] compared with the remifentanil group [ 79 ( 17 ) beats min(-1 ) , 112 ( 15 ) mm Hg ] during emergence and tracheal extubation . Moderate or severe coughing was observed only in the control group ( 8/20 vs 0/20 , P<0.001 ) . CONCLUSIONS Maintaining a remifentanil infusion reduced haemodynamic changes and coughing associated with tracheal extubation almost without significantly delaying recovery from anaesthesia We carried out a controlled , r and omized , double‐blind study to examine the effects of intravenous fentanyl ( 1 or 2 μg kg−1 ) on hemodynamic changes during tracheal extubation and emergence from anesthesia in 60 ASA physical status I or II patients undergoing elective gynecological surgery .  Anesthesia was maintained with 0.5%–1.5 % isoflurane and 60 % nitrous oxide ( N2O ) in oxygen . Muscle relaxation was achieved with vec 
    Output:
    
Conclusion Dexmedetomidine 0.4 to 0.5 ug/kg was associated with smooth extubation , minimal coughing , no laryngospasm/ bronchospasm , and with stable hemodynamics , without causing respiratory depression , PONV , and desaturation .
However , in higher doses ( more than 0.5 ug/kg ) , it caused bradycardia , hypotension , and sedation .
Other pharmacological agents , such as local anesthetics , calcium channel blockers , and opioids , did not attenuate cough associated with extubation