***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: BACKGROUND Postoperative delirium and cognitive decline are common in elderly surgical patients after non-cardiac surgery . Despite this prevalence and clinical importance , no specific aetiological factor has been identified for postoperative delirium and cognitive decline . In experimental setting in a rat model , nitrous oxide ( N(2)O ) produces neurotoxic effect at high concentrations and in an age-dependent manner . Whether this neurotoxic response may be observed clinical ly has not been previously determined . We hypothesized that in the elderly patients undergoing non-cardiac surgery , exposure to N(2)O result ed in an increased incidence of postoperative delirium than would be expected for patients not receiving N(2)O. METHODS Patients who were > or=65 yr of age , undergoing non-cardiac surgery and requiring general anaesthesia were r and omized to receive an inhalational agent and either N(2)O with oxygen or oxygen alone . A structured interview was conducted before operation and for the first two postoperative days to determine the presence of delirium using the Confusion Assessment Method . RESULTS A total of 228 patients were studied with a mean ( range ) age of 73.9 ( 65 - 95 ) yr . After operation , 43.8 % of patients developed delirium . By multivariate logistic regression , age [ odds ratio ( OR ) 1.07 ; 95 % confidence interval ( CI ) 1.02 - 1.26 ] , dependence on performing one or more independent activities of daily living ( OR 1.54 ; 95 % CI 1.01 - 2.35 ) , use of patient-controlled analgesia for postoperative pain control ( OR 3.75 ; 95 % CI 1.27 - 11.01 ) and postoperative use of benzodiazepine ( OR 2.29 ; 95 % CI 1.21 - 4.36 ) were independently associated with an increased risk for postoperative delirium . In contrast , the use of N(2)O had no association with postoperative delirium . CONCLUSIONS Exposure to N(2)O result ed in an equal incidence of postoperative delirium when compared with no exposure to OBJECTIVES To determine whether donepezil hydrochloride can reduce the prevalence and severity of delirium in older adults undergoing hip fracture repair . DESIGN Pilot double-masked r and omized placebo-controlled trial . SETTING Large academic medical center . PARTICIPANTS Sixteen individuals aged 70 and older with hip fracture . INTERVENTION Donepezil 5 mg or placebo was r and omly allocated and initiated within 24 hours of surgery , preoperatively or postoperatively . Daily treatment was continued for 30 days or until side effects or the clinical situation required termination . MEASUREMENTS All outcomes were ascertained masked to treatment status . Information on drug tolerability and safety was obtained from the participant , nurse , and medical record . Delirium presence and severity were measured during daily hospital interviews and at 2 , 4 , and 6 weeks after surgery after a st and ardized assessment using the Confusion Assessment Method ( CAM ) and the Memorial Delirium Assessment Scale ( MDAS ) . RESULTS Participants in the donepezil and placebo arms had similar baseline characteristics . Participants in the donepezil arm experienced significantly more side effects . In longitudinal models , there were no significant differences between the donepezil and placebo arms with regard to delirium presence over time ( odds ratio = 0.9 , 95 % confidence interval ( CI ) = 0.4 - 2.3 ) or delirium severity over time ( effect size = -0.2 on 30-point MDAS scale , 95%CI = -1.5 - 1.2 ) . CONCLUSION Participants r and omized to donepezil had no significant improvement in delirium presence or severity but experienced more side effects . Overall , sufficient evidence was not found from this pilot study to warrant a definitive Phase III trial Background and objectives : Postoperative confusion and delirium is a common complication in the elderly with a poorly understood pathophysiology . The aim of this study was to examine whether the type of anaesthesia ( general or regional ) plays a role in the development of cognitive impairment in elderly patients during the immediate postoperative period . Methods : Forty‐seven patients > 60 yr of age and undergoing major surgery were r and omly allocated to receive either regional or general anaesthesia .  The mental status of the patients was assessed preoperatively and during the first three postoperative days with the Mini Mental State Examination . The incidence of delirium was also examined during the same period with the use of DSM III criteria . Results : Overall , during the first three postoperative days , the mean Mini Mental State Examination score decreased significantly ( P < 0.001 ) . However , this decline was very significant only in patients assigned to receive general anaesthesia ( P < 0.001 ) compared to regional anaesthesia . Nine patients developed delirium but the type of anaesthesia did not affect its incidence . The only important factor for the development of delirium was pre‐existing cardiovascular disease irrespective of anaesthesia type ( P < 0.025 ) . Conclusions : Elderly patients subjected to general anaesthesia  displayed more frequent cognitive impairment during the immediate postoperative period in comparison to those who received a regional technique OBJECTIVE To determine whether limiting intraoperative sedation depth during spinal anesthesia for hip fracture repair in elderly patients can decrease the prevalence of postoperative delirium . PATIENTS AND METHODS We performed a double-blind , r and omized controlled trial at an academic medical center of elderly patients ( > or=65 years ) without preoperative delirium or severe dementia who underwent hip fracture repair under spinal anesthesia with propofol sedation . Sedation depth was titrated using processed electroencephalography with the bispectral index ( BIS ) , and patients were r and omized to receive either deep ( BIS , approximately 50 ) or light ( BIS , > or=80 ) sedation . Postoperative delirium was assessed as defined by Diagnostic and Statistical Manual of Mental Disorders ( Third Edition Revised ) criteria using the Confusion Assessment Method beginning at any time from the second day after surgery . RESULTS From April 2 , 2005 , through October 30 , 2008 , a total of 114 patients were r and omized . The prevalence of postoperative delirium was significantly lower in the light sedation group ( 11/57 [ 19 % ] vs 23/57 [ 40 % ] in the deep sedation group ; P=.02 ) , indicating that 1 incident of delirium will be prevented for every 4.7 patients treated with light sedation . The mean + /- SD number of days of delirium during hospitalization was lower in the light sedation group than in the deep sedation group ( 0.5+/-1.5 days vs 1.4+/-4.0 days ; P=.01 ) . CONCLUSION The use of light propofol sedation decreased the prevalence of postoperative delirium by 50 % compared with deep sedation . Limiting depth of sedation during spinal anesthesia is a simple , safe , and cost-effective intervention for preventing postoperative delirium in elderly patients that could be widely and readily adopted Background Recent studies have indicated that unmanaged pain , both acute and chronic , can affect mental status and might precipitate delirium , especially in elderly patients with hip fractures . The aim of this study was to assess the effectiveness of fascia iliaca compartment block ( FICB ) for prevention of perioperative delirium in hip surgery patients who were at intermediate or high risk for this complication . Material s and methods On admission , all included patients were divided into three groups according to low , intermediate or high risk for perioperative delirium . Eligible patients ( those classified as at intermediate or high risk for developing delirium ) were sequentially r and omly assigned to study treatment ( FICB prophylaxis or placebo ) according to a computer-generated r and omization code . The primary outcome was perioperative delirium . Diagnosis of the syndrome was defined using the Diagnostic and Statistical Manual of Mental Disorders , 4th edition ( DSM-IV ) and Confusion Assessment Method ( CAM ) criteria . Secondary outcome variables were severity of delirium and delirium duration . Results Delirium occurred in 33 ( 15.94 % ) out of 207 patients r and omized to FICB prophylaxis or the placebo group . Incidence of delirium in the FICB prophylaxis group was 10.78 % ( 11/102 ) , significantly different from the incidence ( 23.8 % , 25/105 ) in the placebo group [ relative risk 0.45 , 95 % confidence interval ( CI ) 0.23–0.87 ] . Nine of 17 patients with high risk for delirium and included in the FICB prophylaxis group developed delirium , whereas 10 of 16 high-risk patients included in the placebo group became delirious ( relative risk 0.84 , CI 0.47–1.52 ) . Two of 85 patients with intermediate risk for delirium and included in the FICB prophylaxis group developed delirium , whereas 15 of 89 intermediate-risk patients included in the placebo group became delirious ( relative risk 0.13 , CI 0.03–0.53 ) . Severity of delirium according to the highest value of the DRSR-98 during an episode with delirium in patients in the FICB prophylaxis group was on average 14.34 , versus 18.61 in the placebo group ( mean difference 4.27 , 95 % CI 1.8–5.64 , P < 0.001 ) . Mean duration of delirium in the FICB prophylaxis group was significantly shorter than in the placebo group ( FICB 5.22 days versus placebo 10.97 days , 95 % CI 3.87–7.62 , P < 0.001 ) . Conclusion No significant difference was found among high-risk patients between FICB prophylaxis and placebo groups in terms of delirium incidence . However , FICB prophylaxis significantly prevented delirium occurrence in intermediate-risk patients . Thus FICB prophylaxis could be beneficial , particularly for intermediate-risk patients Background : Intravenous and inhalation anesthesia are commonly used in the clinical setting . Recovery of cognitive function in elderly patients after surgery has received increased attention . In this study , the authors compared recovery of cognitive function in patients after different anesthesia techniques , and investigated which technique is safer . The authors also explored association between apolipoprotein E4 and postoperative cognitive dysfunction in patients undergoing general anesthesia .  Methods : A total of 2,000 patients were equally and r and omly divided into intravenous and inhalation anesthesia groups . Total intravenous and inhalation anesthesia were used . Within 10 days after surgery , cognitive function was assessed daily using the Mini-Mental State Examination ( MMSE ) . Restriction fragment length polymorphism of apolipoprotein E gene was analyzed . The primary outcome was MMSE score , frequency distribution of apolipoprotein E alleles and genotypes . P < 0.01 was used as statistically significant . Results : MMSE score in inhalation preoperative baseline group significantly decreased at day 3 after surgery compared with the preoperational and intravenous anesthesia group . The proportion of patients scoring less than 25 points was significantly greater in the inhalation anesthesia group than in the intravenous anesthesia group at 3 days after surgery . In the inhalation anesthesia group , the decrease in MMSE score was closely related with apolipoprotein E & egr;4 allele . In the intravenous anesthesia group , the decrease in MMSE score was not correlated with apolipoprotein E & egr;4 allele . Conclusions : There was a strong association between the apolipoprotein E & egr;4 and postoperative cognitive dysfunction in elderly patients undergoing inhalation anesthetics BACKGROUND Delirium is a serious postoperative condition for which few pharmacologic prevention trials have been conducted . OBJECTIVE The authors tested the efficacy of perioperative olanzapine administration to prevent postoperative delirium in elderly patients after joint-replacement surgery . METHOD The authors conducted a r and omized , double-blind , placebo-controlled , prophylaxis trial at an orthopedic teaching hospital , enrolling 495 elderly patients age ≥65 years , who were undergoing elective knee- or hip-replacement surgery ; 400 patients received either 5 mg of orally-disintegrating olanzapine or placebo just before and after surgery . The primary efficacy outcome was the incidence of ( DSM-III-R ) delirium . RESULTS The incidence of delirium was significantly lower in the olanzapine group than in the placebo group ; this held true for both knee- and hip-replacement surgery . However , delirium lasted longer and was more severe in the olanzapine group . Advanced age , a high level of medical comorbidity , an abnormal albumin level , and having knee-replacement surgery were independent risk factors for postoperative delirium ( Clinical trials.gov Identifier : NCT000699946 ) . CONCLUSION Administration of 10 mg of oral olanzapine perioperatively , versus placebo , was associated with a significantly lower incidence of delirium . These findings suggest that olanzapine prophylaxis of postoperative delirium may be an effective strategy HYPOTHESIS 
    Output:
    
This meta- analysis has shown that peri-operative geriatric consultations with multicomponent interventions and lighter anaesthesia are potentially effective in decreasing the incidence of postoperative delirium