***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: Cataract surgery is usually performed under topical anesthesia . The procedure is quick and simple to perform and topical anesthesia avoids the potential hazards of a nerve block . However , topical anesthesia may not provide complete anesthesia and may cause anxiety or uncontrolled and unexpected movement . Monitored anesthesia care ( MAC ) is intended to provide anxiety relief , patient comfort , and safety during eye surgery . Propofol , benzodiazepines , and opioids have been used for sedation during cataract surgery [ 1 ] . However each of these drugs causes respiratory depression , hypoxemia , and apnea . The adverse respiratory complications of these drugs may impede the patient ’s cooperation during surgery and increase the need for a sedative drug that can be used safely during MAC . Dexmedetomidine is a central α2 agonist that can be titrated to the desired sedation level without significant respiratory depression and has been used as a primary sedative drug for various surgical and diagnostic procedures [ 2 ] . Unlike other opioids , remifentanil , which is a μ-opioid receptor agonist , has a short elimination half life of 3 - 10 min and a short context sensitive half life of 3 - 5 min . These properties of remifentanil suggest that it may be useful for MAC either combined with propofol or alone [ 3 ] . The aim of this study was to compare dexmedetomidine with remifentanil during cataract surgery in patients under topical anesthesia . The protocol was approved by the Institutional Review Board of our hospital , and all patients provided written informed consent . Eighty American Society of Anesthesiology physical status class 1 - 3 patients ( age , 60 - 80 years ) , who were scheduled for elective cataract surgery under topical anesthesia , were enrolled in this study . Patients were r and omized to receive either dexmedetomidine ( group D ) or remifentanil ( group R ) . Group D patients received an infusion of 0.5 μg/kg dexmedetomidine over 10 minutes followed by a main tenance infusion at a rate of 0.2 μg/kg/hr . Group R patients received remifentanil by target controlled infusion to reach a 1 ng/ml target effect site concentration ( Cet ) . Heart rate ( HR ) , systolic blood pressure , diastolic blood pressure , mean arterial pressure ( MAP ) , respiratory rate ( RR ) , oxygen saturation ( SpO2 ) , bispectral index monitor ( BIS ) and end tidal (ET)CO2 were recorded before infusion ( baseline ) , after the start of infusion , and every 5 minutes after infusion . The degree of sedation was evaluated using the Ramsay sedation scale by an anesthesiologist who was unaware of the type of sedative used . The satisfaction of the patients and surgeon was assessed immediately after surgery using a 7-point Likert-like verbal rating scale . Recovery time was the interval from stopping the infusion to the time when the patient ’s Ramsay sedation score was 2 . Demographic variables were compared using the t-test . Physiological data were analyzed by repeated- measures analysis of variance . The chi-square test was used to compare the sedation and satisfaction scores . No differences in baseline characteristics were observed between the groups . Significantly lower MAP , ETCO2 , and higher RR were observed over time in group D compared with those in group R. No significant differences in HR or SpO 2 were observed between the groups . BIS scores decreased at 10 , 15 , and 20 minutes after infusion , but no significant differences in BIS scores were observed between the groups . More BACKGROUND AND OBJECTIVE To compare dexmedetomidine and midazolam+fentanyl sedation primarily based on patient satisfaction during phacoemulsification under topical and peribulbar anesthesia . PATIENTS AND METHODS Prospect i ve , r and omized , and double-blind study of 80 American Society of Anesthesiology grade I-II patients who underwent phacoemulsification with local anesthesia under sedation . Patients were divided into four groups ( 20 patients for each ) :  dexmedetomidine and topical anesthesia , dexmedetomidine and peribulbar anesthesia , midazolam+fentanyl and topical anesthesia , and midazolam+fentanyl and peribulbar anesthesia . Patient and surgeon satisfaction were determined on a 5-point scale . The pain was determined by verbal pain scale intraoperatively and postoperatively . Drugs were given to a Ramsay sedation scale of 3 . Topical and peribulbar anesthesia were performed by an ophthalmologist . Hemodynamic , respiratory , and intraocular pressure monitoring was done . Operative and recovery times were recorded . RESULTS In the midazolam+fentanyl groups , better patient and surgeon satisfaction scores were obtained ( P < .005 ) , verbal pain scale scores were significantly lower ( P < .001 ) , and patients needed less postoperative analgesia . Ramsay sedation scale scores were between 3 and 4 in all patients and there were no significant differences . Intraocular pressure alterations were similar between groups . Recovery time was longer in the dexmedetomidine groups ( P < .05 ) . CONCLUSION The study demonstrated that the midazolam+fentanyl combination provided high-level patient satisfaction scores , low-level pain scores , and shorter recovery time . Also , both of the peribulbar and topical anesthesia procedures showed similar efficiency Background Dexmedetomidine is a potent and highly specific α2-adrenoreceptor agonist that induces sedative and analgesic effects over a short-term period . As a result of these benefits , dexmedetomidine may be a better alternative than other available drugs for keeping the patient ’s cognition state in an acceptable condition after outpatient ophthalmic surgeries . Objectives This r and omized study was conducted to compare the sedative effects of dexmedetomidine and remifentanil on the cognitive state of patients who have undergone cataract surgery . Patients and Methods A total of 100 patients who were c and i date s for cataract surgery under local anesthesia received either dexmedetomidine ( 50 patients ; D group ) or remifentanil ( 50 patients ; R group ) in a double-blind , r and omized study . The baseline cardiovascular status and mini mental state examination ( MMSE ) score for each patient were recorded . As a loading dose , dexmedetomidine ( 0.5 µg/kg ) and remifentanil ( 0.1 µg/kg ) were infused at 10 minutes and 5 minutes before topical anesthesia , respectively . Subsequently , the maintenance dose was administered at 0.2 µg/kg/hour and 0.05 µg/kg/minutes in the D and R groups , respectively . The surgical procedure was begun when the bispectral index ( BIS ) reached 70 - 80 . MMSE test was done at a postanesthetic care unit ( PACU ) 120 minutes after the discontinuation of the drug . Results There was no statistically significant difference between the MMSE scores of the two groups before surgery ( P = 0.6 ) , but the MMSE test conducted at the PACU revealed significantly better cognitive outcomes in the D group than in the R group in patients younger and older than 65 years ( P = 0.03 and P = 0.0001 , respectively ) . Conclusions This study revealed that dexmedetomidine may be a suitable agent for sedation in cataract surgery because it results in a more favorable postoperative cognitive status  than remifentanil . Likewise , dexmedetomidine had no significant adverse effects on cardiovascular or respiratory systems BACKGROUND Delirium is a postoperative complication that occurs frequently in patients older than 65 years , and presages adverse outcomes . We investigated whether prophylactic low-dose dexmedetomidine , a highly selective α2 adrenoceptor agonist , could safely decrease the incidence of delirium in elderly patients after non-cardiac surgery . METHODS We did this r and omised , double-blind , placebo-controlled trial in two tertiary-care hospitals in Beijing , China . We enrolled patients aged 65 years or older , who were admitted to intensive care units after non-cardiac surgery , with informed consent . We used a computer-generated r and omisation sequence ( in a 1:1 ratio ) to r and omly assign patients to receive either intravenous dexmedetomidine ( 0·1 μg/kg per h , from intensive care unit admission on the day of surgery until 0800 h on postoperative day 1 ) , or placebo ( intravenous normal saline ) . Participants , care providers , and investigators were all masked to group assignment . The primary endpoint was the incidence of delirium , assessed twice daily with the Confusion Assessment Method for intensive care units during the first 7 postoperative days . Analyses were done by intention-to-treat and safety population s. This study is registered with Chinese Clinical Trial Registry , www.chictr.org.cn , number ChiCTR-TRC-10000802 . FINDINGS Between Aug 17 , 2011 , and Nov 20 , 2013 , of 2016 patients assessed , 700 were r and omly assigned to receive either placebo ( n=350 ) or dexmedetomidine ( n=350 ) . The incidence of postoperative delirium was significantly lower in the dexmedetomidine group ( 32 [ 9 % ] of 350 patients ) than in the placebo group ( 79 [ 23 % ] of 350 patients ; odds ratio [ OR ] 0·35 , 95 % CI 0·22 - 0·54 ; p<0·0001 ) . Regarding safety , the incidence of hypertension was higher with placebo ( 62 [ 18 % ] of 350 patients ) than with dexmedetomidine ( 34 [ 10 % ] of 350 patients ; 0·50 , 0·32 - 0·78 ; p=0·002 ) . Tachycardia was also higher in patients given placebo ( 48 [ 14 % ] of 350 patients ) than in patients given dexmedetomidine ( 23 [ 7 % ] of 350 patients ; 0·44 , 0·26 - 0·75 ; p=0·002 ) . Occurrence of hypotension and bradycardia did not differ between groups . INTERPRETATION For patients aged over 65 years who are admitted to the intensive care unit after non-cardiac surgery , prophylactic low-dose dexmedetomidine significantly decreases the occurrence of delirium during the first 7 days after surgery . The therapy is safe . FUNDING Braun Anaesthesia Scientific Research Fund and Wu Jieping Medical Foundation , Beijing , China . Study drugs were manufactured and supplied by Jiangsu Hengrui Medicine Co , Ltd , Jiangsu , China OBJECTIVE The aim of this study is to compare the sedative properties and haemodynamic and respiratory effects of dexmedetomidine and a ketamine-propofol combination ( ketofol ) , which are expected to have minimal effects on spontaneous breathing . METHODS Sixty patients were enrolled in this prospect i ve r and omised study . Patients were divided into 2 groups according to the administration of dexmedetomidine ( Group D ) and ketofol ( Group K ) . Target sedation level was determined as a Ramsay Sedation Score of 3 . In Group D , 0.5 mcg kg(-1 ) dexmedetomidine was administered via intravenous route in 10 minutes versus 0.125 mL kg(-1 ) of a solution containing 200 mg propofol and 100 mg ketamine in Group K.  Haemodynamic and respiratory effects , postoperative awakening time , analgesic properties and satisfaction levels of the patients and surgeon were assessed . RESULTS There was a statistically significant decrease in mean arterial pressures following drug administration compared to initial measurements in both groups . However , there was a statistically significant decrease in heart rate only in Group D. There was no significant difference between the two groups regarding respiratory rate and protection of spontaneous respiration . Although the time for Aldrete score to be 9 was 16.1 minutes for Group K , it was 24.9 minutes for Group D , and this difference was statistically significant ( p<0.01 ) . There was no significant difference between the two groups regarding adverse effects , pain scores and satisfaction levels of the patients and surgeon . CONCLUSION Compared to dexmedetomidine , at similar sedation levels , sedation provided by ketofol enables satisfactory analgesia . Moreover , ketofol has a more rapid onset of action and a shorter recovery period from anaesthesia without causing significant haemodynamic or respiratory adverse effects Purpose To determine the safety and efficacy of perioperative dexmedetomidine ( Dex ) sedation on patient comfort and surgeon satisfaction during cataract surgery under topical anesthesia . Methods Forty-four patients having routine clear corneal phacoemulsification surgery under topical anesthesia were included in the study Patients were r and omly divided into two groups : Dex group ( n=22 ) and control group ( n=22 ) . Patients in the Dex group were to receive intravenous Dex using an infusion pump and those in the control group were to receive 0.9 % saline infusion . Primary outcome measures were patient comfort , surgeon satisfaction , and patient pain perception . Results There was no significant difference between the groups in terms of baseline characteristics including age , sex , eye side , pupil diameter , and vital signs ( p>0.05 for all 
    Output:
    
Delayed PACU discharge times were associated with the use of dexmedetomidine , but no clear association was identified between delayed recovery and higher levels of intraoperative sedation .
Better analgesia and higher patient satisfaction were commonly reported with dexmedetomidine as well as reductions in IOP .
Overall , this review demonstrates better analgesia , higher patient satisfaction , and reduced IOP with dexmedetomidine for outpatient cataract surgery when compared to traditional sedatives , hypnotics , and opioids .
These benefits of dexmedetomidine , however , must be weighed against relative cardiovascular depression and delayed PACU discharge or recovery times .