***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: Using the isolated arm technique , the frequency of awareness was evaluated in 50 full-term patients undergoing elective Caesarean section under general anaesthesia . In 20 patients , anaesthesia was induced with thiopentone 4 mg kg-1 , and in the other 30 patients , induction was with ketamine 1.5 mg kg-1 . Following suxamethonium 1.5 mg kg-1 and tracheal intubation , anaesthesia was supplemented during the induction-delivery period in the thiopentone group with 50 % nitrous oxide and 0.5 % halothane in oxygen in 10 patients , and with 1 % halothane in 100 % oxygen in the other 10 patients . In the ketamine group , the patients underwent ventilation with 50 % nitrous oxide and 0.5 % halothane in oxygen in 10 patients , with 1 % halothane in 100 % in 10 patients , and with 100 % oxygen only in the last 10 patients . Awareness was significantly greater after induction with thiopentone ( 14/20 ) than after ketamine ( 4/30 ) . There were no significant differences in Apgar scores or umbilical vein blood-gas values in the newborns Background : Intraoperative awareness with explicit recall occurs in approximately 0.15 % of all surgical cases . Efficacy trials based on the Bispectral Index ® ( BIS ) monitor ( Covidien , Boulder , CO ) and anesthetic concentrations have focused on high-risk patients , but there are no effectiveness data applicable to an unselected surgical population . Methods : We conducted a r and omized controlled trial of unselected surgical patients at three hospitals of a tertiary academic medical center . Surgical cases were r and omized to alerting algorithms based on either BIS values or anesthetic concentrations . The primary outcome was the incidence of definite intraoperative awareness ; prespecified secondary outcomes included postanesthetic recovery variables . Results : The study was terminated because of futility . At interim analysis the incidence of definite awareness was 0.12 % ( 11/9,376 ) ( 95 % CI : 0.07–0.21 % ) in the anesthetic concentration group and 0.08 % ( 8/9,460 ) ( 95 % CI : 0.04–0.16 % ) in the BIS group ( P = 0.48 ) . There was no significant difference between the two groups in terms of meeting criteria for recovery room discharge or incidence of nausea and vomiting . By post hoc secondary analysis , the BIS protocol was associated with a 4.7-fold reduction in definite or possible awareness events compared with a cohort receiving no intervention ( P = 0.001 ; 95 % CI : 1.7–13.1 ) . Conclusion : This negative trial could not detect a difference in the incidence of definite awareness or recovery variables between monitoring protocol s based on either BIS values or anesthetic concentration . By post hoc analysis , a protocol based on BIS monitoring reduced the incidence of definite or possible intraoperative awareness compared with routine care We examined the feasibility of administering nearly 100 % oxygen throughout the induction-delivery period of general anaesthesia for 113 Caesarean sections .  Isoflurane 1.25 % was compared with 1.5 % enflurane for maintenance of anaesthesia . The level of anaesthesia was monitored by use of the isolated forearm technique . There was a greater amount of isolated forearm movement when enflurane was used . The three main criteria for a satisfactory general anaesthetic technique for Caesarean section were fulfilled , namely no maternal awareness , no undue depression of the fetus and no adverse effect on uterine contractility .  Isoflurane and enflurane appear to be suitable anaesthetic agents for facilitating hyperoxygenation during Caesarean section Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more BACKGROUND Patients who are given general anaesthesia  are not guaranteed to remain unconscious during surgery . Knowledge about the effectiveness of current protective measures is scarce , as is our underst and ing of patients ' responses to this complication . We did a prospect i ve case study to assess conscious awareness during anaesthesia . METHODS 11785 patients who had undergone general anaesthesia  were interviewed for awareness on three occasions : before they left the post-anaesthesia care unit , and 1 - 3 days and 7 - 14 days after the operation . FINDINGS We identified 18 cases of awareness and one case of inadvertent muscle blockade that had occurred before unconsciousness . Incidence of awareness was 0.18 % in cases in which neuromuscular blocking drugs were used , and 0.10 % in the absence of such drugs . 17 cases of awareness were identified at the final interview , but no more than 11 would have been detected if an interview had been done only when the patients left the post-anaesthesia care unit . Four non-paralysed patients recalled intraoperative events , but none had anxiety during wakefulness or had delayed neurotic symptoms . This finding contrasts with anaesthesia with muscle relaxants , during which 11 of 14 patients had pain , anxiety , or delayed neurotic symptoms . After repeated discussion and information , the delayed neurotic symptoms resolved within 3 weeks in all patients . Analysis of individual cases suggests that a reduced incidence of recall of intraoperative events would not be achieved by monitoring of end-tidal anaesthetic gas concentration or by more frequent use of benzodiazepines . INTERPRETATION The inability to prevent awareness by conventional measures may advocate monitoring of cerebral activity by neurophysiological techniques . However , the sensitivity of such techniques is not known , and in the light of our findings , at least 861 patients would need to be monitored to avoid one patient from suffering due to awareness during relaxant anaesthesia Failure of  general anesthesia to render a patient insensate , termed " awareness , " is estimated to affect between 40,000 and 140,000 patients in the US each year . This study investigated the occurrence of post-traumatic stress disorder ( PTSD ) in subjects who reported a past episode of intraoperative awareness . We inquired about intraoperative and postoperative experiences and studied the relationship between various surgical experiences and currently meeting the diagnosis of PTSD . Sixteen postawareness subjects and 10 postgeneral anesthesia controls completed the  Clinician Administered PTSD Scale ( CAPS )  , a st and ardized  clinical rating scale for PTSD  , and a question naire about peri-operative experiences .  Nine of 16 subjects ( 56.3 % ) , a mean of 17.9 postoperative years , and no controls met diagnostic criteria for current PTSD ( X(2)= 8.6 , df = 1 , P<.01 ) . Common intraoperative experiences included an inability to communicate , helplessness , terror , and pain . Postawareness patients had significant postoperative distress related to feeling unable to communicate , unsafe , terrified , ab and oned and betrayed . Perioperative dissociative experiences predicted having current PTSD . Being conscious during surgery is a traumatic event that may result in developing chronic PTSD . Further studies should include prospect i ve design s of prevalence and long-term psychological , social , and overall health effects , and ways of preventing and treating awareness-induced PTSD Using the isolated forearm technique ( IFT ) , we wished to determine if patients known to be unresponsive to comm and s during general anaesthesia with nitrous oxide , halothane and neuromuscular blocking agents  had any evidence of explicit or implicit recall .  Two groups of women , studied in a single-blind sequential block design , heard different tapes , either a comm and and information tape ( n = 34 ) or radio static ( n = 34 ) , throughout surgery . Four women ( two radio static , two comm and ) had unequivocal evidence of explicit recall for a period near the beginning or end of the procedure , at a time when the IFT was not being used . With or without hypnosis , category generation , serial position of category exemplars and word association tests did not reveal evidence of priming . We conclude that during light general anaesthesia with nitrous oxide , halothane and atracurium , patients had neither explicit nor implicit memory for information presented during a period when they are known to be unresponsive to comm and Background : The isolated forearm technique allows assessment of consciousness of the external world ( connected consciousness ) through a verbal comm and to move the h and ( of a tourniquet-isolated arm ) during intended general anesthesia . Previous isolated forearm technique data suggest that the incidence of connected consciousness may approach 37 % after a noxious stimulus . The authors conducted an international , multicenter , pragmatic study to establish the incidence of isolated forearm technique responsiveness after intubation in routine practice . Methods : Two hundred sixty adult patients were recruited at six sites into a prospect i ve cohort study of the isolated forearm technique after intubation . Demographic , anesthetic , and intubation data , plus postoperative question naires , were collected . Univariate statistics , followed by bivariate logistic regression models for age plus variable , were conducted . Results : The incidence of  isolated forearm technique responsiveness after intubation was 4.6 % ( 12/260 ) ; 5 of 12 responders reported pain through a second h and squeeze . Responders were younger than nonresponders ( 39 ± 17 vs. 51 ± 16 yr old ; P = 0.01 ) with more frequent signs of sympathetic activation ( 50 % vs. 2.4 % ; P = 0.03 ) . No participant had explicit recall of intraoperative events when question ed after surgery ( n = 253 ) . Across groups , depth of anesthesia monitoring values showed a wide range ; however , values were higher for responders before ( 54 ± 20 vs. 42 ± 14 ; P = 0.02 ) and after ( 52 ± 16 vs. 43 ± 16 ; P = 0.02 ) intubation . In patients not receiving total intravenous anesthesia , exposure to volatile anesthetics before intubation reduced the odds of responding ( odds ratio , 0.2 [ 0.1 to 0.8 ] ; P = 0.02 ) after adjustment for age . Conclusions : Intraoperative connected consciousness occurred frequently , although the rate is up to 10-times lower than anticipated . This should be considered a conservative estimate of intraoperative connected consciousness BACKGROUND Awareness during anesthesia is foremost assessed with postoperative interviews , which may underestimate its incidence . On-line monitors such as the Bispectral Index and patient response to verbal comm and are not necessarily commonly used . This study investigated response to comm and during deep sedation ( Bispectral Index 60 - 70 ) and the ability of prevailing monitoring techniques to indicate awareness and predict recall . METHODS The authors systematic ally assessed the response to comm and using the isolated forearm technique while monitoring electroencephalographic and hemodynamic variables .  Fifty-six elective surgical patients were repeatedly given verbal instructions to squeeze the observer 's h and during target-controlled infusion with propofol and alfentanil . After recovery , conscious recall was assessed with a short structured interview . RESULTS Overall , 1,082 comm and s were given . No response was observed to 887 ( 82 % ) comm and s , an equivocal response was observed to 56 ( 5 % ) comm and s , and an unequivocal response was observed to 139 ( 13 % ) comm and s. Of the 37 patients ( 66 % ) with an unequivocal response to comm and ( " awareness " ) , nine ( 25 % ) reported conscious recall after recovery . Their reports provided valuable insights as to how awareness may be adequately addressed . Hemodynamic variables poorly predicted awareness , whereas parameters derived from the encephalogram , especially the Bispectral Index , were highly significant predictors ( P < 0.0001 ) . Electroencephalographic parameters did not discriminate between patients with or without conscious recall , whereas heart rate and responsiveness to comm and did . CONCLUSIONS The incidence of awareness is underestimated when conscious recall is taken as evidence . Awareness can be monitored on-line with behavioral and modern neurophysiologic measures . Providing feedback during intra-anesthetic awareness helps patients to cope with a potentially stressful situation Little is known about the effect of anesthetic management on long-term outcomes . We design ed a prospect i ve observational study of adult patients undergoing major noncardiac surgery with general anesthesia  to determine if mortality in the first year after surgery is associated with demographic , preoperative clinical , surgical , or intraoperative variables .  One-year mortality was 5.5 % in all patients ( n = 1064 ) and 10.3 % in patients ≥65 yr old ( n = 243 ) . Multivariate Cox Proportional Hazards modeling identified three variables as significant independent predictors of mortality : patient comorbidity ( relative risk , 16.116 ; P < 0.0001 ) , cumulative deep hypnotic time ( Bispectral Index ® < 45 ) ( relative risk = 1.244/h ; P = 0.0121 ) and intraoperative systolic hypotension ( relative risk = 1.0 
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Proportions of IFT‐positive patients decreased significantly with increasing age and premedication use .
Conclusions St and ard general anaesthesia regimens might not prevent connected consciousness .