***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: Background and Objectives : A triple-injection technique ( injections at the median , musculocutaneous , and radial nerves ) for axillary block affords a high incidence of complete block ( all the nerves below the elbow ) . However , in certain surgeries , only 1 or 2 nerves are involved in the surgical field . The aim of this prospect i ve r and omized study was to test the effectiveness of surgical anesthesia of a " selective " approach in which only the nerves involved in surgery were electrically located and injected . Methods : Three types of surgery were selected . Type 1 included surgery on the fifth finger , type 2 included superficial surgery ( without bone involvement ) on the palm or on the dorsum of the h and , and type 3 included any surgery on the first 3 fingers . For each type , 138 patients were enrolled and divided into 2 groups : group SEL in which only the nerves involved in the surgical field ( 1 or 2 ) were located and injected and group TNS in which a st and ard triple-nerve stimulation technique was used . Results : A lower rate of surgical anesthesia ( 84 % vs 92 % ; P < 0.05 ) was recorded in group SEL considered as a whole : this was mainly due to the significant difference recorded in type 2 surgery ( 75 % vs 93 % ; P < 0.05 ) . More patients needed intravenous administration of fentanyl for tourniquet pain ( 18 % vs 8 % ; P < 0.005 ) and of midazolam for intraoperative anxiety ( 20 % vs 8 % ; P < 0.005 ) in group SEL considered as a whole . In type 1 , improved patient comfort at block performance ( P < 0.05 ) , a 7-min saving on total anesthetic time ( P < 0.001 ) , and a higher need for midazolam administration ( P < 0.05 ) were recorded in group SEL . In type 2 , a higher need for midazolam administration ( P < 0.05 ) was recorded in group SEL . In type 3 , no clinical ly significant differences between the groups were recorded . Conclusions : A st and ard triple-nerve stimulation technique seems to be preferable to the selective approach even when a limited number of nerves are involved in the surgical field The perivascular technique of axillary brachial plexus block results in incomplete block of radial and musculocutaneous nerves in 10 - 20 % of patients . With the transarterial technique and a large dose of mepivacaine , success rates of 99 % have been reported . We have compared the clinical efficacy of these techniques in 50 patients using 1 % mepivacaine 45 ml with adrenaline . If required , the block was supplemented with additional blocks of single nerves or i.v . alfentanil . Additionally , eight patients in each group were studied with  computed tomography  after contrast medium was added to 0.5 % bupivacaine 40 ml . There were no statistically significant differences in sensory or motor block between the groups at 20 min or in the plasma concentrations of mepivacaine measured 0 - 45 min after injection . In the CT scans , both proximal and distal spread of the contrast medium were more common after perivascular than after transarterial block . The distribution of the contrast medium was not related to the efficacy of the block Perivascular axillary blockade was performed on 90 patients with the aid of a catheter technique . The patients were r and omly allocated to receive either 40 , 50 or 60 ml of 1 % mepivacaine with adrenaline 1:200,000 . Blood concentrations of mepivacaine were measured up to 90 min after injection in seven , eight and ten of the patients from the three groups . Sensory and motor blockade was evaluated 20 , 30 and 40 min after injection . All groups showed the same temporal development of the blockade , i.e. improval of the blockade during the period from 20 to 40 min after injection , but no difference was found in the sensory or motor blockade between the three groups . However , a further analysis of the incomplete blockades showed a better quality of the sensory blockade in the groups given 50 and 60 ml than in the group given 40 ml . None of the 90 patients showed any signs of systemic toxic reactions . The mean peak values of blood concentrations were 0.5‐1.0 μg/ml higher in the groups A given 50 ml and 60 ml than in the group given 40 ml . On the basis of the present and two previous investigations on the dose response in perivascular axillary blockade , a dose of 50 ml 1 % mepivacaine with adrenaline or I r another equivalent drug with vasoconstrictor is recommended Perivascular  axillary blockade  was performed on 90 patients with the aid of a catheter technique . All blockades were performed by the same anaesthetist , who practised perivascular axillary blockade three or four times a day . The patients were r and omly allocated to three groups . The injected volume of local anaesthetic was constant in each group : 40 ml mepivacaine with adrenaline . The concentration and , consequently , the amount ( mg ) were variable factors : ½% ( 200 mg ) , 1 % ( 400 mg ) and 1½% ( 600 mg ) . Sensory and motor blockade were tested 30 min after each injection . All three groups showed a high incidence of analgesia ( 70%‐100 % ) in all cutaneous segments , and none of the blockades showed total failure of the sensory blockade . The lowest incidence of sensory blockade was found in the areas innervated by the axillary , the radial and the musculocutaneous nerves , but no difference was found between the groups . However , the motor blockade was found to improve with increasing concentration of local anaesthetic solution Comparison of the trans-arterial and Winnie techniques of axillary brachial plexus block was made in two groups of patients . This study did not find any statistical difference between the two techniques This prospect i ve , r and omized , double-blind study compared two techniques of axillary brachial plexus block using a peripheral nerve stimulator . Both groups received initial musculocutaneous nerve block followed by either a single injection on median nerve stimulation ( group 1 ) or a double injection divided between median and radial nerves ( group 2 ) . All 60 patients received a total of 30 ml of lidocaine 15 mg/ml with epinephrine 5 microg/ml .  Complete sensory blockade of all six peripheral nerves occurred in 53 % and 97 % of patients in groups 1 and 2 , respectively ( P<0.001 ) , with a more rapid onset of blockade occurring in group 2 patients ( P<0.001 ) . Complete motor blockade was evident in 30 % and 83 % of patients in groups 1 and 2 , respectively ( P<0.001 ) Background and Objectives The multiple-injection technique for axillary block , in which the main 4 nerves of the plexus are located by a nerve stimulator and separately injected , has been shown to produce a high success rate . However , this technique may prove to be more difficult and time-consuming than other methods . Therefore , a simplified technique , with a reduced number of injections , might be desirable . A comparison between 2- and 3-injection techniques was made in the present double-blind study . Methods One hundred patients were r and omly allocated to 2 groups . In group 3N , the radial , median , and musculocutaneous nerves were located by a nerve stimulator and injections made . In group 2N , the radial and median nerves were located and injections made . Forty milliliters of local anesthetic was used . Results A greater success rate for anesthetizing the musculocutaneous nerve was found in group 3N ( 98 % v 80 % ; P < .005 ) . No differences between the groups were found in the success rate for blocking the radial , median , and ulnar nerves . The rate of complete block ( all the sensory areas distal to the elbow ) was 90 % in group 3N and 76 % in group 2N . The time to perform the block was shorter in group 2N ( 5 ± 1 v 6 ± 1 minutes ; P < .001 ) . Conclusions The 2-injection technique offers a success rate in blocking the 3 nerves innervating the h and similar to that obtained with the 3-injection technique . The latter approach should be considered when the musculocutaneous nerve distribution is involved in the surgical area STUDY OBJECTIVE To investigate the comfort and satisfaction of patients with trauma of the upper limb during two different techniques of axillary brachial plexus block , electrical nerve stimulation and fascial pop . DESIGN R and omized- prospect i ve , observational study . SETTING University surgical center . PATIENTS 100 ASA physical status I and II patients undergoing surgery for trauma of the h and and forearm . INTERVENTIONS Patients received axillary brachial plexus block with a mixture of 0.5 % bupivacaine and 2 % lidocaine . They were then allocated to one of two groups to receive either electrical nerve stimulation ( Group 1 , n = 50 ) , or fascial pop technique ( Group 2 , n = 50 ) for nerve location . MEASUREMENTS Data were collected on patient demographics , surgery , frequency of complications , and sedation required during the block . Discomfort during the block and surgical comfort were quantified by visual analog scale ( 0 - 10 ) . Satisfaction was determined by the following scale : very satisfied , satisfied , dissatisfied , and very dissatisfied . Patients also indicated if in the future they would like to receive the same method of anesthesia . MAIN RESULTS No differences in demographic or surgical data were found . No serious complications were observed . Eighteen Group 1 patients ( 36 % ) and none in Group 2 needed sedation during the blocks . Discomfort during the procedures was greater in Group 1 than Group 2 ( 4.5 + /- 1.2 vs 1.5 + /- 1 , P < 0.05 ) , while patients reported good surgical comfort with both techniques ( 2.4 + /- 2.9 vs 2.2 + /- 2.1 , NS ) . Eighteen patients in Group 1 and 48 patients in Group 2 would accept the same block for future surgery . CONCLUSIONS In trauma patients , the fascial pop technique is effective , reduces sedation during axillary brachial plexus block , and has a higher patient acceptance rate than the electrical nerve stimulation technique BACKGROUND AND OBJECTIVES The multiple-injection technique for axillary block , in which the 4 distal nerves of the plexus are located by a nerve stimulator and separately injected , has been shown to produce a rapid onset and a high success rate . However , this technique may be more difficult and time consuming than other axillary block methods . A simplified multiple-nerve stimulation technique , in which the ulnar nerve was not located , was compared in the present double-blind study to the 4-injection approach . METHODS Eighty-four patients were r and omly allocated to 2 groups . In group IV , all 4 distal nerves of the plexus were located by a nerve stimulator and injections made . In group III , all the nerves but the ulnar were located and injections made . The block was defined as complete when analgesia was present in all the sensory areas distal to the elbow . RESULTS The time to perform the block was shorter in group III ( 5 + /- 2 v 8 + /- 3 minutes ; P < .001 ) . Block performance pain was lower in group III patients ( 8 + /- 2 v 13 + /- 2 mm ; P < .001 ) . The onset time ( 15 + /- 6 v 16 + /- 7 minutes ) and the frequency ( 90 % v 92 % ) of complete block were not different between the groups . CONCLUSIONS A triple-injection method of axillary block in which the ulnar nerve was not purpose ly located provides a spread and a latency of sensory block equal to that obtained with a 4-injection technique . A shorter performance time is an advantage of this approach INTRODUCTION : In this prospect i ve , r and omized , double-blind study , we compared the effectiveness and time efficiency of perioperative axillary blocks performed via 2 different techniques , 1 involving 2 and the other 4 separate skin punctures . METHODS : One hundred twenty patients undergoing upper limb surgery were r and omized to receive either ( 1 ) an axillary brachial plexus block involving 2 injections , with 30 mL local anesthetic injected posterior to the axillary artery ( with redirection , as needed , to achieve circumferential spread ) , plus 10 mL local anesthetic to the musculocutaneous nerve , guided by ultrasound ( group 1 , n = 56 ) ; or ( 2 ) 4 separate 10-mL injections to the median , ulnar , radial , and musculocutaneous nerves , using a combined ultrasound and neurostimulation technique ( group 2 , n = 58 ) . All patients received 40 mL of 0.5 % ropivacaine with 1:400,000 epinephrine . The primary outcome was the success rate of the block , defined as anesthesia adequate for surgery . Secondary outcomes were the time to administer the block , time to the onset of motor-sensory block , time to surgical readiness , and incidence of adverse events . RESULTS : The 2-injection technique was slightly faster to administer ( 8 vs 11 minutes , P = 0.003 ) . The mean nerve block score was slightly higher for the 4-injection group at the 10- , 15- , 
    Output:
    
Subgroup analysis by method of nerve location showed that the effect size was greater when neurostimulation was used rather than the transarterial technique .
Otherwise , there were no statistically significant differences between groups in any of the three comparisons on secondary analgesia failure , complications and patient discomfort .
The time for block performance was significantly shorter for single and double injections compared with multiple injections .
AUTHORS ' CONCLUSIONS This review provides evidence that multiple injection techniques using nerve stimulation for axillary plexus block produce more effective anaesthesia than either double or single injection techniques .
However , there was insufficient evidence for a significant difference in other outcomes , including safety