***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: St and ardized behavioural observations were used to establish the influence of the type of anaesthesia on the mental function and the subjective physical well-being in 60 patients , all men , following urological surgery . The patients were r and omized to two groups , receiving spinal or general anaesthesia .  For evaluation of the influence of pre-operative physical condition on post-operative mental function , a supplementary group of 34 patients with pre-existing cardiovascular and /or pulmonary disorders was included in the study . These patients all received spinal anaesthesia . The patients were observed from the day before surgery until 4 weeks after . In all patients a short-lasting temporary decline in mental function was observed . The outcome was not influenced by the type of anaesthesia . In the two groups receiving spinal anaesthesia the decline in post-operative mental function and subjective sense of well-being was most pronounced in patients with a compromised physical condition pre-operatively . Four weeks after surgery , no signs of mental deterioration were present ; however , the subjective sense of physical well-being had not fully returned This study compared the effects of general and regional anesthesia on cognitive and psychosocial functioning in elderly persons . Sixty-four patients between 60 and 86 yr of age undergoing knee arthroplasty were r and omly assigned to receive either general or regional anesthesia . A battery of psychometric tests , including the Satz-Mogel form of the Wechsler Adult Intelligence Scale-Revised , the Wechsler Memory Scale-Revised and the Sickness Impact Profile , and various neuropsychological measures were administered by a blinded observer just before surgery and again 3 months later . Analyses of covariance revealed improvements in most measures that were equivalent between groups . The results indicated that there were no cognitive or psychosocial effects of general or regional anesthesia after 3 months in elderly persons undergoing knee arthroplasty . In this patient population , general anesthesia poses no more risk to long-term mental function than regional anesthesia 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 Background : Postoperative cognitive dysfunction ( POCD ) is a common complication after cardiac and major non‐cardiac surgery with general anaesthesia in the elderly . We hypothesized that the incidence of POCD would be less with regional anaesthesia rather than general OBJECTIVE --To determine the influence of general or regional anaesthesia on long term mental function in elderly patients . DESIGN -- Prospect i ve study of patients r and omly allocated to receive general or regional anaesthesia .  SETTING --The patients ' homes and a large teaching hospital in Cardiff . SUBJECTS--146 Patients aged 60 and over scheduled for elective hip or knee replacement .  MAIN OUTCOME MEASURES --Scores achieved in tests of cognitive function and functional competence . RESULTS --72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia . Anaesthetic technique did not influence the duration of the operation , time to mobilisation postoperatively , requirements for analgesia after the operation , or duration of stay in hospital . Three months after the operation there was an improvement in the score for the recognition component ( 76 ms , 95 % confidence interval 9 to 144 ) and the response component ( 82 ms , 5 to 158 ) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia . This was the only significant difference between the two groups in the assessment s of cognitive and functional competence . Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation , but this was not confirmed by testing . CONCLUSION --Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function To evaluate whether there is a difference in mental function after general anaesthesia and epidural analgesia , a homogeneous group of 40 elderly men ( age between 60 and 80 ) undergoing transurethral prostatectomy was studied . The study was prospect i ve , r and omised and double blind . Patients with all types of complications believed to impair mental function were excluded .  Long‐term , short‐term , verbal and visual memory were tested preoperatively , and 4 days , and 3 weeks postoperatively . In conclusion , we found a significant and equal decline in test performance on the fourth postoperative day . Three weeks postoperatively , however , both groups had returned to or exceeded preoperative levels of performance One hundred and one patients were r and omly allocated to have their peripheral vascular surgery performed under general anaesthesia ( 51 patients ) or spinal anaesthesia ( 50 patients ) .  Intraoperative haemodynamic changes were markedly different between the two groups with a higher incidence of hypotension in the spinal group ( 72 % vs 31 % ) and a higher incidence of hypertension in the general anaesthesia group ( 22 % vs 0 % ) . Blood loss was significantly less in the spinal group ( 560 , SD 340 , ml vs 792 , SD 440 , ml ) . Postoperatively three patients from the general anaesthesia group died from causes unrelated to the anaesthesia , and one had a myocardial infa rct . Two patients in the spinal group had myocardial infa rcts , both had been treated for bradycardia and hypotension intraoperatively , and one died . There was a significantly higher incidence of postoperative chest infection in the general anaesthesia group ( 33 % vs 16 % ) . There was no significant difference between the groups in the incidence of postoperative confusion , or lower limb amputation rate or need for further surgery prior to hospital discharge Forty elderly patients ( mean age 78.9 years ) undergoing acute surgery for hip fracture were given at r and om either spinal analgesia with bupivacaine 0.75 % or general anaesthesia with diazepam , fentanly and N2O/O2 . Mental function was studied pre‐operatively with an abbreviated mental test and 1 week and 3 months postoperatively in both groups . Mortality and number of complications was similar in the two groups , but a shorter time of ambulation was seen in the spinal group compared to the general anaesthetic group . No persistent impairment in mental function was found after acute hip surgery under spinal or general anaesthesia and the only advantage of regional technique was a shorter time of ambulation One hundred and sixty‐nine patients ( aged 65–98 years ) were r and omised to receive either local or general anaesthesia for cataract surgery .  Cognitive function was assessed using a battery of psychometric tests performed pre‐operatively , and at 24 h , 2 weeks and 3 months postoperatively . Oxygen saturation , blood pressure and heart rate were monitored and the results recorded throughout the anaesthetic and immediate recovery period . In the general anaesthetic group , 19 % of patients experienced at least one episode of oxygen desaturation during the procedure compared with none in the local anaesthetic group . Pulse rate and blood pressure were stable in the local anaesthetic group compared with the general anaesthetic group where marked fluctuations were noted ; 61 % of patients in the general anaesthetic group experienced falls in systolic blood pressure greater than 30 % of the pre‐induction value . No evidence of long‐term postoperative cognitive dysfunction was detected and there was no significant difference between the performances of the two groups The psychological effects of halothane , methoxyflurane , combined analgesic-relaxant anaesthesia , and epidural anaesthesia were assessed before one , and seven days after anaesthesia in 72 patients having operations for varicose veins .  Subjective anxiety evaluation ( Hamilton Anxiety Rating Scale ) and personality tests of self- appraisal ( Minnesota Multiphasic Personality Inventory ) as well as of superficial ( Wartegg 's test ) and profound ( Rorschach 's test ) projection showed no significant differences among these methods of anaesthesia . Performance tests measuring memory for design s ( modified Graham-Kendall memory for design s ) , short-term memory ( digit span of Wechsler Adult Intelligence Scale ) , learning ( nonsense word series ) , perception ( symmetry-drawing ) , speed of observation ( Bourdon-Wiersma ) and visualization also revealed no significant psychological changes compared to the control ( epidural anaesthesia ) group . The methods of anaesthesia used therefore showed no harmful psychological effects and are in this respect safe in clinical use This study compared the postoperative mental function in 44 elderly patients following general anaesthesia ( GA ) or spinal anaesthesia ( SA ) with sedation for transurethral resection of prostate .  The Mini-Mental State ( MMS ) was done preoperatively and postoperatively at six hours , one day , three days , five days and one month . The geriatric mental status examination was performed preoperatively and one month after the anaesthetic . There was no significant intergroup difference in the MMS score in the preoperative , six hours , one day , three days , five days and 30 days postoperative scores between the GA and SA with sedation groups . A significant intragroup difference between preoperative and postoperative MMS score was detected in the GA group ( P < 0.02 ) and in the SA group with sedation ( P < 0.03 ) . In the GA group , the significant decrease in MMS score occurred at 6 h postoperatively ( P < 0.002 ) whereas in the SA group with sedation , MMS score also decreased significantly at 6 h ( P < 0.005 ) . In conclusion , there was no significant difference in perioperative mental function between the general and spinal anaesthetic groups when supplemental IV sedation was given . In both groups , perioperative mental function decreased significantly at 6 h postoperatively . RésuméDans ce travail , nous comparons les fonctions mentales de 44 patients agés , après une résection trans-urétrale de la prostate sous anesthésie soit  générale  ( AG ) soil rachidienne avec sédation ( ARS ) . Nous avons fait un examen mental gériatrique ( GEMS ) avant et un mois après l’opération ainsi qu’un examen plus sommaire , le Mini-Mental State ( MMS ) juste avant et 6 , 24 , 72 , et 120 heures de même qu ’ un mois après l’intervention . Avec le MMS , nous n’avons pas identifié de différence significative entre les deux groupes à quelque moment que ce soit . A l’intérieur de chacun des deux groupes cependant , on a noté une baisse des résultats au MMS entre le préet le post-opératoire ( P < 0.02 pour AG et P < 0.03 pour ARS ) qui était détectable six heures après l’intervention ( P < 0.002 pour AG et P < 0.005 pour ARS ) . L’état mental post-opératoire des patients n’était done pas dépendant du type d’anesthésie , qu’elle soil générale ou rachidienne avec sédatifs par vote intraveineuse OBJECTIVE To develop and vali date a clinical prediction rule for postoperative delirium using data available to clinicians preoperatively . DESIGN Prospect i ve cohort study . SETTING General surgery , orthopedic surgery , and gynecology services at Brigham and Women 's Hospital , Boston , Mass. PATIENTS Consenting patients older than 50 years admitted for major elective noncardiac surgery between November 1 , 1990 , and March 15 , 1992 ( N = 1341 ) . MEASUREMENTS All patients underwent preoperative evaluations , including a medical history , physical examination , laboratory tests , and assessment s of physical and cognitive function using the Specific Activity Scale and the Telephone Interview for Cognitive Status . Postoperative delirium was diagnosed using the Confusion Assessment Method or using data from the medical record and the hospital 's nursing intensity index . Patients were followed up for the duration of hospitalization to determine major complication rates , length of stay , and discharge disposition . RESULTS Postoperative delirium occurred in 117 ( 9 % ) of the 1341 patients studied . Independent correlates included age 70 years or older ; self-reported alcohol abuse ; poor cognitive status ; poor functional status ; markedly abnormal preoperative serum sodium , potassium , or glucose 
    Output:
    
In conclusion , it appears that general anesthesia , compared to others , may increase the risk of developing POCD ; however this has not been shown for POD .