***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: In a double‐blind trial the effects of a single dose of doxapram ( 1–1.5 mg/kg ) on the postoperative arterial oxygen tension  of patients who had undergone surgical fixation of a fractured neck of femur was measured . In contrast to other reports of the effect of a single dose of doxapram , there was no improvement in arterial oxygen tension with respect to the control group . It is reasoned that doxapram may exert its effect by increasing the functional residual capacity in the immediate postoperative period . The central analeptic properties of doxapram may be grossly underestimated Postoperative cognitive dysfunction ( POCD ) has been attributed to long-acting sedatives . We hypothesized that diazepam and its active metabolites could be detected in blood after surgery and correlated with POCD , 1 week after surgery in elderly patients . We studied 35 patients , 60 yr or older , undergoing abdominal surgery with general anaesthesia , including diazepam .  Neuropsychological tests were performed before surgery and at discharge , where blood concentrations ( free fraction ) of benzodiazepines were also measured . POCD was found in 17 patients ( 48.6 % ) . Diazepam or desmethyldiazepam was detected in 34 patients ; median postoperative blood concentrations were 0.06 and 0.10 mumol kg-1 , respectively . In a multiple regression analysis considering age , duration of anaesthesia and blood concentrations of diazepam and desmethyldiazepam , only age was found to correlate with the composite z-score ( F test , P < 0.01 ) . The postoperative cognitive dysfunction we found in elderly patients after operation could not be explained by benzodiazepine concentrations detected in blood Spinal block causes paralysis of preganglionic sympathetic fibres , while ketamine induces activation of the sympathetic nervous system . Hypotension is a frequent complication during spinal anaesthesia and is associated with an increased risk of postoperative mortality . The aim of our study was to compare circulatory changes in patients who received either fentanyl or ketamine during spinal anaesthesia . Thirty patients ( ASA I‐III ) scheduled to undergo spinal anaesthesia for osteo synthesis of hip fractures were allocated to receive either ketamine or fentanyl intravenously during the procedure . Immediately before anaesthesia , 7 ml/kg BW of an isotonic NaCl solution was administered i.v . Patients received either fentanyl 1.5 mg/kg BW i.v . before anaesthesia , or ketamine 0.7 mg/kg BW i.v . before anaesthesia , and 0.35 mg/kg BW 15 and 30 min after the first dose . No prophylactic vasopressor was used . During the first 40 min of anaesthesia a fluid load of 14 ml/kg BW was given i.v . If the mean arterial pressure ( MAP ) fell more than 20 % , the infusion rate was increased . If the reduction in MAP exceeded 33 % or if the systolic pressure decreased to less than 80 mmHg , patients were registered as haemodynamically unstable . In both groups the spinal anaesthesia caused a reduction in MAP . The MAP was lower in the fentanyl group than in the ketamine group at all times . In the kentanyl group six subjects developed a haemodynamically unstable condition , while only one subject in the ketamine group was registered as such ( P<0.05 ) . There was no significant change in heart rate in either group . We conclude that during spinal anaesthesia patients can in part be kept haemodynamically stable by intravenous administration of ketamine We have compared the haemodynamic effects of ephedrine alone with ephedrine and colloid for the treatment of  hypotension  produced by subarachnoid anaesthesia in 30 patients aged 60 - 90 yr with fractures of the neck of femur . Group one received ephedrine as an initial bolus dose of 0.2 mg kg-1 followed by an infusion of 0.5 mg kg-1 h-1 . Group two received ephedrine and colloid ( polygeline , Haemaccel ) 8 ml kg-1 . If necessary , up to three rescue bolus doses of ephedrine ( 0.1 mg kg-1 ) and then colloid solution ( 8 ml kg-1 ) were given to maintain systolic arterial pressure ( SAP ) at > 75 % of baseline . Arterial pressure was measured by automated oscillotonometry , central venous pressure ( CVP ) by a manometer and cardiac index ( CI ) , stroke index ( SI ) and heart rate ( HR ) by transthoracic electrical bioimpedance . Systemic vascular resistance index ( SVRI ) was derived . In patients receiving ephedrine only , SVRI , CVP and SI decreased and HR increased ( P < 0.0001 ) . Five patients in this group required colloid , the effect of which was to restore CVP , increase CI and SI , and decrease HR ( P < 0.02 ) . In patients receiving ephedrine and colloid solution , SVRI decreased and CI , SI and HR increased ( P < 0.0001 ) . Ephedrine was not a potent arterial vasoconstrictor and SAP was maintained mainly by increases in SI and HR One hundred patients presenting for surgical treatment of fractured neck of femur were allocated to receive either spinal ( SAB ) or general ( GA ) anaesthesia . Before operation , the mean PaO2 was 9.04 kPa . There was a significant decrease in PaO2 of 0.68 kPa in GA group at 1 h after operation , while blood-gas values were unchanged in SAB group . Eight patients ( 15.7 % ) in GA group and five patients ( 10.2 % ) in SAB group died within 4 weeks of surgery . The difference was not statistically significant Thirty patients undergoing total hip replacement were r and omly allocated to one of two groups . One group ( n = 14 ) received extradural anaesthesia with 0.5 % bupivacaine with adrenaline continued into the postoperative period ( 24 h ) for pain relief . The other group ( n = 16 ) received general anaesthesia with controlled ventilation , using nitrous oxide in oxygen and fentanyl i.v . Following surgery they received a narcotic analgesic i.m . on dem and . Analysis of fibrinolysis inhibition activity and plasminogen activators revealed a significantly better fibrinolytic function in patients given continuous extradural anaesthesia than in those who received general anaesthesia followed by narcotics in the period after operation . Furthermore , the capacity for activation of factor VIII was significantly lower after operation in the former group Background Perioperative myocardial ischemia occurs in 35 % of unselected elderly patients undergoing hip fracture surgery .  Perioperative epidural analgesia may reduce the incidence of adverse cardiac events . Methods The effect of early administration of epidural analgesia during the stressful presurgical period , on preoperative cardiac events was evaluated in a prospect i ve r and omized study in 68 patients with hip fractures who either had known coronary artery disease or were at high risk for coronary artery disease . On admission to the emergency room , patients were assigned to receive a usual care analgesic regimen ( intramuscular meperidine , control group , n = 34 ) or continuous epidural infusion of local anesthetic and opioid ( epidural group , n = 34 ) . Monitoring in the preoperative period included a preoperative history and physical examination , daily assessment of cardiac adverse events , serial electrocardiograms , cardiac enzymes , and pain scores . Results Preoperative adverse cardiac events were significantly more prevalent in the control group compared with the epidural group ( 7 of 34 vs. 0 of 34;P = 0.01 ) . Adverse cardiac events included fatal myocardial infa rct ion in three , fatal congestive heart failure in one , nonfatal congestive heart failure in one , and new onset atrial fibrillation in two . The incidence of intraoperative and postoperative adverse cardiac events was similar for the two groups . The significant difference between groups in the incidence of preoperative cardiac events prompted interruption of the study after the planned interim analysis . Conclusions The authors ’ data indicate that compared with conventional analgesia , early administration of continuous epidural analgesia is associated with a lower incidence of preoperative adverse cardiac events in elderly patients with hip fracture who have or are at risk for coronary artery disease . Preoperative epidural analgesia may be advantageous for this surgical population Fifty-five patients presenting with fractured neck of femur were r and omly allocated to either a st and ard general anaesthetic or spinal block in the lateral position combined with light sedation . The comparability of the two groups was established . There was little difference in the intra-operative course of postoperative morbidity in the two groups . There was a statistically significant difference in post-operative mortality between two groups , the general anaesthetic group showing a much higher mortality than the spinal group 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 The aim of this study was to compare hypobaric solutions of tetracaine and bupivacaine in 30 geriatric patients undergoing surgical repair of hip fractures while under continuous spinal anesthesia .  Tetracaine 1 % and bupivacaine 0.5 % were mixed with distilled water to prepare hypobaric 0.25 % solutions . In a double-blind fashion , all patients received 3 ml ( 7.5 mg ) of either solution in the lateral decubitus position with the operated side up , the table being kept horizontal for 30 minutes after injection . The mean highest sensory levels in both groups , and in both operated and non-operated sides in the same group , were comparable , ranging between T7 and T8.5 . Duration of analgesia was 134 minutes with tetracaine and 130 minutes with bupivacaine ( NS ) . In both groups , motor blockade was satisfactory in 29/30 patients on the operated side . The frequency of a decrease in systolic blood pressure of more than 30 % was similar in the two groups . The authors conclude that hypopobaric solutions of both tetracaine and bupivacaine are suitable for surgical repair of hip fractures in geriatric patients and produce comparable anesthetic and hemodynamic effects BACKGROUND AND OBJECTIVES This prospect i ve r and omized study was design ed to determine the hemodynamic effects and quality of combined lumbar and sacral plexus block compared with plain bupivacaine spinal anesthesia in the elderly for repair of proximal femoral fractures . METHODS Twenty-nine elderly patients ranging in age from 68 to 97 years were r and omly assigned to 2 groups : a spinal anesthesia group with single-shot 3 mL 0.5 % plain bupivacaine , and a combined block group with 30 mL lidocaine 1.33 % with epinephrine for the posterior lumbar plexus block and 10 mL same mixture for the parasacral block and an iliac crest block with 5 mL lidocaine 1 % . RESULTS No need for general anesthesia was encountered in either group . Anesthesia was judged unsatisfactory in 1 of 15 patients in the combined block group . The initial decrease of mean arterial pressure was 38 % in the spinal group and 27 % in the block group and was not significantly different . A more prolonged hemodynamic effect was found in the spinal group , indicated by the more frequent use of ephedrine to stabilize blood pressure ( P<.05 ) . Patients over 85 years had a significantly larger decrease in blood pressure than younger patients ( P<.01 ) . CONCLUSIONS Plain bupivacaine spinal anesthesia and combined lumbar/sacral plexus block provided adequate anesthesia for repair of hip fracture in the elderly . Hypotension was induced by both the combined peripheral nerve block and plain bupivacaine spinal anesthesia in aged patients ; hypotension was found to be longer lasting after spinal anesthesia and of a larger magnitude in patients over 85 years of age During a prospect i ve r and omized trial , 50 geriatric patients underwent surgery for a fractured femoral neck . The perioperative circulatory and respiratory effects of anesthesia with enflurane or balanced anesthesia with enflurane and fentanyl were compared . We were particularly looking for postoperative respiratory depression after a st and ard dose of fentanyl given during balanced anesthesia . Method . In 25 patients anesthesia was induced with 0.2 mg/kg etomi date and 1 mg/kg succinylcholine and maintained with 0.15 mg/kg alcuronium and enflurane .  Twenty-five patients received a additional dose of 5 micrograms/kg 
    Output:
    
Regional anaesthesia may reduce acute postoperative confusion but no conclusions can be drawn for mortality or other outcomes