***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: OBJECTIVE To assess the use of ultrasound guidance to enable injection of 10 mL of 2 % mepivacaine into the brachial plexus to maintain an effective block and surgical conditions comparable to those that can be provided with larger volumes and higher doses . MATERIAL AND METHODS This was a prospect i ve study of 200 consecutive adults in whom a 7.5 Mhz linear array was used for ultrasound guidance of a 40-mm 21-gauge needle  with a 15 degrees bevel tip . The probe was placed in the coronal oblique plane and the needle was inserted along its axis to the outer edge . The anesthetic was injected at 3 locations . The quality of sensory block was assessed at 30 minutes and effectiveness at the end of surgery . RESULTS The patient sample consisted of 87 women and 113 men with a mean ( SD ) age of 40 ( 13 ) years and body mass index of 26 ( 4 ) kg x m(-2 ) . Most procedures were on the h and and elbow ( 82 % ) . All blocks were performed by the same anesthesiologist . Sensory block of pain was achieved in 97 % of the patients and analgesia was effective for 95 % . Paresthesias were noted by 28 % when the needle was moved and by 71.5 % during injection . The only complications observed were 2 arterial punctures ( 1 % ) . CONCLUSIONS Ultrasound guidance enables use of less local anesthetic for supraclavicular brachial plexus blocks . The surgical conditions possible are comparable in quality to those achieved at higher volumes and doses . The incidence of complications is minimal STUDY OBJECTIVE To assess the clinical use of ultrasonographic localization of the epidural space , and to evaluate the clinical efficacy of ultrasound diagnostics in obstetric anesthesia . DESIGN R and omized prospect i ve study . SETTING University Clinic of Obstetrics and Gynecology . PATIENTS 300 parturients , 85 of whom had conventional delivery and 65 who underwent cesarean section . INTERVENTIONS Patients underwent ultrasonography for the identification of the intervertebral structures . Puncture depth and angle were measured to improve the placement of the Tuohy needle . MEASUREMENTS In the ultrasound group , additional puncture data , optimized puncture point , expected puncture depth , and angle were used to optimize the puncture technique . To control for side effects , we compiled data on the number of puncture attempts and the number of necessary puncture levels , visual analog scale ( VAS ) scores , the rate of side effects , and the patient acceptance of the technique . MAIN RESULTS The two groups were similar regarding demographic data . Using ultrasound for structure detection , the rate of puncture attempts were significantly ( p < 0.013 ) reduced from 2.18 + /- 1.07 to 1.35 + /- 0.61 . The mean rate of necessary puncture levels was 1.30 + /- 0.55 and with ultrasound detection 1.136 + /- 0.36 ( p < 0.029 ) . Complete analgesia was achieved in 147 patients with ultrasound detection versus 138 patients in the Control group ( p < 0,03 ) . The maximum VAS pain score in the control group was 1.3 + /- 2.1 versus 0.8 + /- 1.5 in the Ultrasound group ( p < 0.006 ) . The rate of side effects were reduced significantly : 99 patients in the Control group had no side effects compared with 120 patients from the Ultrasound group who were free of side effects . Patient acceptance of the technique in the Ultrasound group was significantly higher than in the Control group . CONCLUSION The clinical use of ultrasound for epidural catheter placement may improve regional anesthesia . The use of ultrasound result ed in superior quality in all measured endpoints Background and Objectives  Pediatric epidural anesthesia  has increased in popularity in the last 2 decades , but its success rate and the frequency of complications has not been fully eluci date d. We therefore review ed our experience with 2,050 cases of epidural anesthesia in infants and children . Methods We recorded the number of attempts at epidural space location , complications , and effectiveness in 2,050 cases of single-shot sacral intervertebral , lumbar , and thoracic epidural anesthesia .  We used the drip and tube method for identification of the epidural space and administration of local anesthetic solution . Results The overall rate of successful epidural block and epidural space location on the first attempt was 96.4 % and 89.8 % , respectively . Complications included uncomplicated dural penetration ( 0.54 % ) , spinal anesthesia ( 0.05 % ) , bloody tap ( 0.34 % ) , and intravascular injection ( 0.20 % ) . Complications were more frequent in patients ≤10 kg body weight . There were no permanent neurological sequelae . Conclusions Intervertebral epidural anesthesia using the “ drip and tube ” method is safe and practical in infants and children . Reg Anesth Pain Med 2003;28:103 - 107 Background Several previous surveys have estimated the rate of major complications that occur after regional anesthesia . However , because of the increase in the use of regional anesthesia in recent years and because of the introduction of new techniques , re appraisal of the incidence and the characteristics of major complications is useful . Methods All French anesthesiologists were invited to participate in this 10-month prospect i ve survey based on ( 1 ) voluntary reporting of major complications related to regional anesthesia occurring during the study period using a telephone hotline service available 24 h a day and managed by three experts , and ( 2 ) voluntary reporting of the number and type of regional anesthesia procedures performed using pocket booklets . The service was free of charge for participants . Results The participants ( n = 487 ) reported 56 major complications in 158,083 regional anesthesia procedures performed ( 3.5/10,000 ) . Four deaths were reported . Cardiac arrest occurred after spinal anesthesia ( n = 10 ; 2.7/10,000 ) and posterior lumbar plexus block ( n = 1 ; 80/10,000 ) . Systemic local anesthetic toxicity consisted of seizures only , without cardiac toxicity .  Lidocaine spinal anesthesia was associated with more neurologic complications than bupivacaine spinal anesthesia ( 14.4/10,000 vs. 2.2/10,000 ) . Most neurologic complications were transient . Among 12 that occurred after peripheral nerve blocks , 9 occurred in patients in whom a nerve stimulator had been used . Conclusion This prospect i ve survey based on a free hotline permanent telephone service allowed us to estimate the incidence of major complications related to regional anesthesia and to provide a detailed analysis of these complications Background : Nerve puncture by the block needle and intraneural injection of local anesthetic are thought to be major risk factors leading to neurologic injury after peripheral nerve blocks . In this study , the author sought to determine the needle – nerve relation and location of the injectate during ultrasound-guided axillary plexus block . Methods : Using ultrasound-guided axillary plexus block ( 10-MHz linear transducer , SonoSite , Bothel , WA ; 22-gauge B-bevel needle , Becton Dickinson , Franklin Parks , NJ ) , the incidence of apparent nerve puncture and intraneural injection of local anesthetic was prospect ively studied in 26 patients . To determine the onset , success rate , and any residual neurologic deficit , qualitative sensory and quantitative motor testing were performed before and 5 and 20 min after block placement . At a follow-up 6 months after the blocks , the patients were examined for any neurologic deficit . Results : Twenty-two of 26 patients had nerve puncture of at least one nerve , and 21 of 26 patients had intraneural injection of at least one nerve . In the entire cohort , 72 of a total of 104 nerves had intraneural injection . Sensory and motor testing before and 6 months after the nerve injections were unchanged . Conclusions : Under the conditions of this study , puncturing of the peripheral nerves and apparent intraneural injection during axillary plexus block did not lead to a neurologic injury BACKGROUND We report a prospect i ve , r and omized study to evaluate ultrasound guidance for epidural catheter placement in children 0 - 6 yr of age . METHODS Epidural catheters were placed at lumbar or thoracic cord levels in 64 children undergoing major surgery , using either ultrasonography or loss-of-resistance ( LOR ) for guidance . Using a 5 - 10 MHz linear ultrasound probe , the neuraxial structures were identified , the skin-epidural depth and epidural space was measured , the advancing epidural catheter visualized , and the spread of local anaesthetic verifying catheter position was confirmed . Epidural placement procedures were analysed for bone contacts and speed of execution . Children under 6 months were analysed separately . RESULTS Epidural placement involved bone contacts in 17 % of children in the ultrasound group and 71 % of children in the LOR group ( P<0.0001 ) . Epidurals were executed more swiftly in the ultrasound group [ 162 ( 75 ) s vs 234 ( 138 ) s ; P<0.01 ] . Children under 6 months revealed a 0.9 correlation between skin-epidural depth and body weight . CONCLUSIONS Ultrasonography is a useful aid to verify epidural placement of local anaesthetic agents and epidural catheters in children . Advantages include a reduction in bone contacts , faster epidural placement , direct visualization of neuraxial structures and the spread of local anaesthetic inside the epidural space .  Ultrasound guidance requires additional training and good manual skills , and should only be used once experience in ultrasound-guided techniques of regional anaesthesia has been acquired Background : This prospect i ve , r and omized , blinded study tested the hypothesis that ultrasound guidance can shorten the onset time of axillary brachial plexus block  as compared with nerve stimulation guidance when using a multiple injection technique . Methods : Sixty American Society of Anesthesiology physical status I – III patients receiving axillary brachial plexus block with 20 ml ropivacaine , 0.75 % , using a multiple injection technique , were r and omly allocated to receive either nerve stimulation ( group NS , n = 30 ) , or ultrasound guidance ( group US , n = 30 ) for nerve location . A blinded observer recorded the onset of sensory and motor blocks , the need for general anesthesia ( failed block ) or greater than 100 & mgr;g  fentanyl  ( insufficient block ) to complete surgery , procedure-related pain , success rate , and patient satisfaction . Results : The median ( range ) number of needle passes was 4 ( 3–8 ) in group US and 8 ( 5–13 ) in group NS ( P = 0.002 ) . The onset of sensory block was shorter in group US ( 14 ± 6 min ) than in group NS ( 18 ± 6 min ) ( P = 0.01 ) , whereas no differences were observed in onset of motor block ( 24 ± 8 min in group US and 25 ± 8 min in group NS ; P = 0.33 ) and readiness to surgery ( 26 ± 8 min in group US and 28 ± 9 min in group NS ; P = 0.48 ) . No failed block was reported in either group . Insufficient block was observed in 1 patient ( 3 % ) of group US and 2 patients ( 6 % ) of group NS ( P = 0.61 ) . Procedure-related pain was reported in 6 patients ( 20 % ) of group US and 14 patients ( 48 % ) of group NS ( P = 0.028 ) ; patient acceptance was similarly good in the two groups . Conclusion : Multiple injection axillary block with ultrasound guidance provided similar success rates and comparable incidence of complication as compared with nerve stimulation guidance Background : Tibial and common peroneal nerves can be blocked by the posterior approach to the popliteal fossa . Techniques using fixed measured distances between knee skin crease and puncture point have been described . We report on an approach that is based on manual identification of the apex of the popliteal fossa . Methods : Five-hundred patients undergoing surgery of ankle or foot were prospect ively included . The apex of the popliteal fossa ( determined by the crossing point of the biceps femoris and the semitendinosus and semimembranosus muscles ) was assessed by manual palpation . The puncture point was 0.5 cm below the apex , on the medial side of the biceps femoris muscle . When indicated for postoperative analgesia , a perineural catheter was placed . We assessed success rate , number of attempts , the distance between knee skin crease and the apex of the popliteal fossa , nerve depth , and acute and late complications . Results : Block success rate was 94 % and 92 % when the block was performed through the needle and the catheter , respectively . Inversion was the motor response with the highest success rate . The first attempt was successful in 97.5 % of the patients . Mean depth of the nerve was 4.5 cm ( range , 2.0 to 7.0 cm ) and mean knee skin crease to apex of popliteal fossa distance 
    Output:
    
Overall , the RCTs and case series reported that use of ultrasound significantly reduced time or number of attempts to perform blocks and in some cases significantly improved the quality of sensory block .
Current evidence does not suggest that use of ultrasound improves success of regional anesthesia versus most other techniques .
However , ultrasound was not inferior for efficacy , did not increase risk , and offers other potential patient-oriented benefits .