***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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    Input: We studied 52 adults undergoing elective craniotomy , allocated r and omly to one of three opioid treatments : alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 until dural closure ( group Alf . ) ; alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 for 2 h , then remifentanil 0.25 microgram kg-1 min-1 ( group Alf.-Remi . ) ; or remifentanil 1 microgram kg-1 followed by 0.5 microgram kg-1 min-1 reducing to 0.25 microgram kg-1 min-1 after craniotomy ( group Remi . ) . Anaesthesia was maintained with infusion of propofol and 66 % nitrous oxide in oxygen . Infusions of propofol and remifentanil were stopped at head b and aging . Group Remi . had the least intraoperative haemodynamic responses and group Alf . the most ( P < 0.05 ) . Times to tracheal extubation and obey comm and s were similar in all groups . In all patients in group Alf.-Remi . and group Remi . , the trachea was extubated 27 min from the end of anaesthesia ; three patients in group Alf . were slower to recover . Use of analgesia in the recovery room and time to transfer to the neurosurgical unit were similar in the three groups OBJECTIVE Large bolus-dose remifentanil may be advantageous for use during induction of anesthesia because of its short duration of effect . Currently , there are little data on the use of large bolus-dose remifentanil because of reports of severe bradycardia and hypotension . The purpose of this study is to compare the hemodynamic effects of bolus remifentanil versus fentanyl with glycopyrrolate for induction of anesthesia in patients with heart disease . DESIGN A r and omized , double-blinded study . SETTING A tertiary-care academic medical center . PARTICIPANTS One hundred patients for coronary artery bypass or valvular surgery . INTERVENTION Subjects received either ( 1 ) remifentanil , 5 microg/kg , with glycopyrrolate , 0.2 mg , or ( 2 ) fentanyl , 20 microg/kg , with 0.2 mg of glycopyrrolate , and both groups also received midazolam , 70 microg/kg , for induction of anesthesia . MEASUREMENTS AND MAIN RESULTS Heart rate , mean arterial pressure , systemic vascular resistance , and cardiac output were similar between the 2 groups during induction of anesthesia and tracheal intubation . The incidence of adverse events such as bradycardia ( remifentanil 10 % , fentanyl 10 % ) , hypotension ( remifentanil 16 % , fentanyl 10 % ) , and ischemia ( remifentanil 0 % , fentanyl 2 % ) were also similar . A greater percentage of patients in the remifentanil group lost consciousness within 1 minute of opioid administration ( 86 % v 66 % , p = 0.034 ) . CONCLUSION Remifentanil with glycopyrrolate is associated with rapid and predictable clinical anesthetic effect , cardiac stability , and the ability to blunt the hemodynamic responses to tracheal intubation . Bolus remifentanil may be a feasible alternative to bolus fentanyl for induction of anesthesia in patients with heart disease because of its short duration of action and its ability to blunt the hemodynamic responses to tracheal intubation The purpose of this study was to test the hypothesis that using a 1:4 ratio of remifentanil to alfentanil , a remifentanil infusion would provide better suppression of intraoperative responses and comparable recovery profiles after ambulatory laparoscopic surgery than an alfentanil infusion , as part of total intravenous anesthesia . Two hundred ASA physical status I , II , or III adult patients participated in this multicenter , double-blind , parallel group study . Patients were r and omly assigned 2:1 to either the remifentanil-propofol or alfentanil-propofol regimens . The anesthesia sequence was propofol ( 2 mg/kg intravenously [ IV ] followed by 150 micro g [ centered dot ] kg ( -1 ) [ centered dot ] min-1 ) , and either remifentanil ( 1 micro g/kg IV followed by 0.5 micro g [ centered dot ] kg-1 [ centered dot ] min-1 ) or alfentanil ( 20 micro g/kg IV followed by 2 micro g [ centered dot ] kg-1 [ centered dot ] min ( -1 ) ) , and vecuronium . After trocar insertion , infusion rates were decreased ( propofol to 75 micro g [ centered dot ] kg-1 [ centered dot ] min-1 ; remifentanil to 0.25 micro g [ centered dot ] kg-1 [ centered dot ] min-1 ; alfentanil to 1 micro g [ centered dot ] kg-1 [ centered dot ] min-1 ) . Alfentanil and propofol were discontinued at 10 and 5 min , respectively , before the anticipated end of surgery ( last surgical suture ) ; remifentanil was discontinued at the end of surgery . Recovery times were calculated from the end of surgery . The median duration of surgery was similar between groups ( 39 min for remifentanil versus 34 min for alfentanil ) . A smaller proportion of remifentanil patients than alfentanil patients had any intraoperative responses ( 53 % vs 71 % , P = 0.029 ) , had responses to trocar insertion ( 11 % vs 32 % , P < 0.001 ) , or required dosage adjustments during maintenance ( 24 % vs 41 % , P < 0.05 ) . Early awakening times were similar . Remifentanil patients qualified for Phase 1 discharge later and were given postoperative analgesics sooner than alfentanil patients ( P < 0.05 ) . Actual discharge times from the ambulatory center were similar between groups ( 174 min for remifentanil versus 204 min for alfentanil ) ( P = 0.06 ) . In conclusion , remifentanil can be used for maintenance of anesthesia in a 1:4 ratio compared with alfentanil , for total IV anesthesia in ambulatory surgery . This dose of remifentanil provides more effective suppression of intraoperative responses and does not result in prolonged awakening . ( Anesth Analg 1997;84:515 - 21 INTRODUCTION The aim of this study was to investigate how many patients , after anesthesia with either propofol/remifentanil or propofol/fentanyl/alfentanil , within 20 minutes from the end of surgery could be transferred directly to the general ward . The number of undesired preoperative incidents , the anesthetists ' , the surgeons ' , and the patients ' evaluations of the anesthesia were registered . An evaluation of the economic consequences of the two methods was also intended . MATERIAL AND METHODS The study was clinical ly controlled , r and omised , and partly blinded . A total of 80 patients undergoing eye surgery were recruited . The patients were scored 10 , 15 , and 20 minutes after the end of surgery according to a modified Aldrete score . With sufficient awakening score , the patients were transferred to the general ward . RESULTS Thirty-six patients in each group underwent the examination . In the propofol/remifentanil-group 31 ( 86 % ) could be transferred to the general ward compared to 15 ( 42 % ) in the proponol/fentanyl/alfentanil-group . In the propofol/remifentanil-group there were less reactions to the start of surgery , more episodes with preoperative hypotension and postoperative shivering . Otherwise there were no differences between the groups . It was estimated that the additional expenses for medcine were by far outweighed by the lower costs postoperatively . DISCUSSION With a propofol/remifentanil-anesthesia , the patients had a predictably short awakening time , so they could be transferred directly to the general ward . This may , especially in ambulatory surgery , mean cost savings and perhaps higher patient satisfaction We compared a fentanyl/isoflurane/propofol regimen with a remifentanil/isoflurane/propofol regimen for fast-track cardiac anesthesia in a prospect i ve , r and omized , double-blinded study on patients undergoing elective coronary artery bypass graft surgery . Anesthesia was induced with a 1-min infusion of 0.5 mg/kg propofol followed by 10-mg boluses of propofol every 30 s until loss of consciousness . After 0.2 mg/kg cisatracurium , a blinded continuous infusion of remifentanil at 1 & mgr;g · kg−1 · min−1 or the equivalent volume rate of normal saline was then started . In addition , a blinded bolus syringe of 1 & mgr;g/kg remifentanil or 10 & mgr;g/kg fentanyl , respectively , was given over 3 min . Blinded remifentanil , 1 & mgr;g · kg−1 · min−1 ( or the equivalent volume rate of normal saline ) , together with 0.5 % isoflurane , were used to maintain anesthesia . Significantly more patients ( P < 0.01 ) in the fentanyl regimen experienced hypertension during skin incision and maximum sternal spread compared with patients in the remifentanil regimen . There were no differences between the groups in time until extubation , discharge from the surgical intensive care unit , ST segment and other electrocardiogram changes , catecholamine levels , or cardiac enzymes . The remifentanil-based anesthetic ( consisting of a bolus followed by a continuous infusion ) result ed in significantly less response to surgical stimulation and less need for anesthetic interventions compared with the fentanyl regimen ( consisting of an initial bolus , and followed by subsequent boluses only to treat hemodynamic responses ) with both drug regimens allowing early extubation STUDY OBJECTIVES To compare the intraoperative effects and recovery characteristics of remifentanil hydrochloride and alfentanil when administered as part of balanced anesthesia , and to assess the effects of an additional remifentanil infusion administered as analgesic pretreatment before removal of the uterus . DESIGN Multicenter , double-blind , r and omized , parallel-group study . SETTING Two university hospitals . PATIENTS 35 ASA physical status I , II , and III women scheduled for elective total abdominal hysterectomy with general endotracheal anesthesia . INTERVENTIONS Patients were premedicated with midazolam 0.05 mg/kg intravenously ( i.v . ) . Anesthesia was induced with thiopental 2 mg/kg , vecuronium 0.15 mg/kg , and a single dose of opioid over 60 seconds ( Pump 1 ) : remifentanil 2 micrograms/kg ( Remi/Placebo and Remi/Remi groups ) or alfentanil 50 micrograms/kg ( Alf/Placebo group ) . Anesthesia was maintained with a nitrous oxide/oxygen mixture ( 66:34 ratio ) and a continuous opioid infusion : remifentanil 0.25 microgram/kg/min ( Remi/Placebo and Remi/Remi ) or alfentanil 0.5 microgram/kg/min ( Alf/Placebo ) . At skin incision , a second blinded drug infusion was also initiated ( Pump 2 ) : remifentanil 0.25 microgram/kg/min ( Remi/Remi ) or saline placebo ( Remi/Placebo and Alf/Placebo ) . Intraoperative responses were controlled with single doses of opioid and /or rate titrations via Pump 1 . Pump 2 was terminated on removal of the uterus . Pump 1 was terminated at skin closure . MEASUREMENTS AND MAIN RESULTS The mean ( + /- SD ) opioid infusion rates administered for the duration of Pump 2 to suppress responses to removal of the uterus were 0.49 + /- 0.27 microgram/kg/min , 1.99 + /- 1.34 micrograms/kg/min , and 0.49 + /- 0.07 microgram/kg/min for the Remi/Placebo , Alf/Placebo , and Remi/Remi groups , respectively . At these rates , similar proportions of patients in the Remi/Placebo ( 67 % ) and the Alf/Placebo ( 60 % ) groups had responses . Fewer patients had responses in the Remi/Remi group ( 8 % ) compared with the Remi/Placebo and Alf/Placebo groups ( p < 0.05 ) . The mean total opioid doses used during maintenance were 84.6 micrograms/kg ( Remi/Placebo ) , 393 micrograms/kg ( Alf/Placebo ) , and 68.7 micrograms/kg ( Remi/Remi ) . Awakening times were significantly shorter ( p < 0.05 ) in the remifentanil population compared with the alfentanil population , but discharge times were similar . More patients received  naloxone to reverse opioid effects in the alfentanil population ( 60 % ) than in the remifentanil population ( 20 % ) ( p < 0.0 
    Output:
    
Remifentanil does not seem to offer any advantage for lengthy , major interventions , but may be useful for selected patients , e.g. when postoperative respiratory depression is a concern