Retroclavicular vs supraclavicular brachial plexus block for distal upper limb surgery: a randomised,controlled, single-blinded trial

Background

Regional anaesthesia for upper limb surgery is routinely performed with brachial plexus blocks. A retroclavicular brachial plexus block has recently been described, but has not been adequately compared with another approach. This randomised controlled single-blinded trial tested the hypothesis that the retroclavicular approach, when compared with the supraclavicular approach, would increase the success rate.

Initial placement and secondary displacement of a new suture‐method catheter for sciatic nerve block in healthy volunteers: a randomised,double‐blind pilot study

We performed a randomised double‐blind pilot study in 16 healthy volunteers to investigate the success rate for placing a new suture‐method catheter for sciatic nerve block. A catheter was inserted into both legs of volunteers and each was randomly allocated to receive 15 ml lidocaine 2% through the catheter in one leg and 15 ml saline in the other leg. Successful placement of the catheter was defined as a 20% decrease in maximum voluntary isometric contraction for dorsiflexion of the ankle. Secondary outcomes were maximum voluntary isometric contraction for plantar flexion at the ankle, surface electromyography and cold sensation. After return of motor and sensory function, volunteers performed standardised physical exercises; injection of the same study medication was repeated in the same leg and followed by motor and sensory assessments. Fifteen of 16 (94%; 95%CI 72–99%) initial catheter placements were successful. The reduction in maximum voluntary isometric contraction and surface electromyography affected the peroneal nerve more often than the tibial nerve. Eleven of 15 (73%; 95%CI 54–96%) catheters remained functional with motor and sensory block after physical exercise, and the maximal displacement was 5 mm. Catheters with secondary block failure were displaced between 6 and 10 mm. One catheter was displaced 1.8 mm that resulted in a decrease in maximum voluntary isometric contraction of less than 20%. After repeat test injection, 14 of the 16 volunteers had loss of cold sensation. Neither motor nor sensory functions were affected in the legs injected with placebo. We conclude that the suture‐method catheter can be placed with a high success rate, but that physical exercise may cause displacement.     

Local anaesthetic adjuncts for peripheral regional anaesthesia: a narrative review

Moderate-to-severe postoperative pain persists for longer than the duration of single-shot peripheral nerve blocks and hence continues to be a problem even with the routine use of regional anaesthesia techniques. The administration of local anaesthetic adjuncts, defined as the concomitant intravenous or perineural injection of one or more pharmacological agents, is an attractive and technically simple strategy to potentially extend the benefits of peripheral nerve blockade beyond the conventional maximum of 8–14 hours. Historical local anaesthetic adjuncts include perineural adrenaline that has been demonstrated to increase the mean duration of analgesia by as little as just over 1 hour. Of the novel local anaesthetic adjuncts, dexmedetomidine and dexamethasone have best demonstrated the capacity to considerably improve the duration of blocks. Perineural dexmedetomidine and dexamethasone increase the mean duration of analgesia by up to 6 hour and 8 hour, respectively, when combined with long-acting local anaesthetics. The evidence for the safety of these local anaesthetic adjuncts continues to accumulate, although the findings of a neurotoxic effect with perineural dexmedetomidine during in-vitro studies are conflicting. Neither perineural dexmedetomidine nor dexamethasone fulfils all the criteria of the ideal local anaesthetic adjunct. Dexmedetomidine is limited by side-effects such as bradycardia, hypotension and sedation, and dexamethasone slightly increases glycaemia. In view of the concerns related to localised nerve and muscle injury and the lack of consistent evidence for the superiority of the perineural vs. systemic route of administration, we recommend the off-label use of systemic dexamethasone as a local anaesthetic adjunct in a dose of 0.1–0.2 mg.kg⁻¹ for all patients undergoing surgery associated with significant postoperative pain.     

Comparison of the analgesic effect of an adductor canal block using a new suture-method catheter vs. standard perineural catheter vs. single-injection: a randomised,blinded, controlled study

We performed a randomised, blinded, controlled study with adult patients scheduled for primary total knee arthroplasty under spinal anaesthesia. The aim was to investigate the analgesic effects of adductor canal block using catheter-based repeated boluses, either through a new suture-method catheter or a standard perineural catheter, compared with a single-injection technique. All patients received an adductor canal block after surgery with an initial bolus of 20 ml ropivacaine 0.75%, followed by 20 ml of ropivacaine 0.2% every 8 h in the standard and suture-method catheter groups, and sham boluses for the single-injection group. The primary outcome measure was total opioid consumption (intravenous morphine equivalents) from the end of surgery until 12:00 on postoperative day 2. Secondary outcomes were pain, muscle strength and ambulation. We randomly assigned (1:1:1) and analysed 153 patients. Total opioid consumption was median (IQR [range]) 24 (11–37 [0–148]) mg in the suture-method group, 38 (17–51 [0–123]) mg in the standard catheter group and 37 (14–57 [0–158]) mg in the single-injection group (p = 0.049). Differences were not statistically significant after Bonferroni correction (α = 0.05/3). There were no differences between groups on postoperative day 1. On postoperative day 2, there were no differences between catheter groups, but muscle strength and ambulation were improved compared with the single-injection group. We conclude that providing repeated boluses via a catheter did not decrease opioid consumption or pain compared with a single injection, but improved muscle strength and ambulation on postoperative day 2. The two types of catheters were similar.     

Supraclavicular continuous peripheral nerve block in a wounded soldier: when ultrasound is the only option

The complex nature of combat-related injuries requires frequentoperative interventions and prolonged analgesic therapy. Theapplication of continuous peripheral nerve block (CPNB) hasbeen an important anaesthetic tool in the management of combatsoldiers wounded from the current conflicts. The severe, destructivenature of combat injuries makes placement of CPNB difficultor impossible using more common neurostimulation approaches.The use of ultrasound technology has improved our success inplacing CPNB in the presence of such injuries. We report theapplication of ultrasound technology in placing CPNB in a combat-injuredsoldier, whose injuries precluded other CPNB options.     

Effects of ultrasound guidance on the minimum effective anaesthetic volume required to block the femoral nerve

Background: We tested the hypothesis that ultrasound guidance may reducethe minimum effective anaesthetic volume (MEAV₅₀) of ropivacaine0.5% required to block the femoral nerve compared with nervestimulation guidance. Methods: After standard premedication and sciatic nerve block were given,60 patients undergoing knee arthroscopy were randomly allocatedto receive a femoral nerve block with ropivacaine 0.5% usingeither nerve stimulation (group NS, n = 30) or ultrasound (groupUS, n = 30) guidance. The volume of the injected solution wasvaried for consecutive patients based on an up-and-down staircasemethod according to the response of the previous patient. Theinitial volume was 12 ml. A double-blinded observer evaluatedthe occurrence of complete loss of pinprick sensation in thefemoral nerve distribution, with concomitant block of the quadricepsmuscle: positive or negative responses within 30 min after theinjection determined a 3 ml decrease or increase for the nextpatient, respectively. Results: The mean (SD) MEAV₅₀ for femoral nerve block was 15 (4) ml (95%CI, 7–23 ml) in group US and 26 (4) ml (95% CI, 19–33ml) in group NS (P = 0.002). The effective dose in 95% of cases(ED₉₅) calculated with probit transformation and logistic regressionanalysis was 22 ml (95% CI, 13–36 ml) in group US, and41 ml (95% CI, fs 24–66 ml) in group NS. Conclusions: Ultrasound guidance provided a 42% reduction in the MEAV ofropivacaine 0.5% required to block the femoral nerve as comparedwith the nerve stimulation guidance.     

Spinal versus peripheral effects of adjunct clonidine: comparison of the analgesic effect of a ropivacaine-clonidine mixture when administered as a caudal or ilioinguinal-iliohypogastric nerve blockade for inguinal surgery in children

BACKGROUND: The adjunctive use of clonidine to local anaesthetics has been reported to enhance analgesia both after spinal and peripheral administration. However, no attempt has been made to compare spinal and peripheral application of clonidine in the same surgical context in order to further explore the mechanism for the analgesic action of clonidine when administered together with local anaesthetics. METHODS: Using a prospective, randomized, observer-blinded study design, 40 patients, aged 1-7 years, who were undergoing elective surgery for inguinal hernia repair or orchidopexy, were randomly allocated to receive either a caudal block (group C: n = 20; ropivacaine 0.2%, 1 ml.kg-1 + clonidine 2 micro g.kg-1) or an ilioinguinal-iliohypogastric nerve block (group I: n = 20; ropivacaine 0.2%, 0.4 ml.kg-1 + clonidine 2 micro g.kg-1) following the induction of a standardized sevoflurane based anaesthetic. Postoperative analgesia [maximum Objective Pain Scale (OPS) score and requirement for supplemental analgesia] and sedation (three-point scale) were assessed at predetermined intervals during the first 24 h postoperatively. RESULTS: Fourteen children in group I and nine children in group C did not require rescue analgesia (P = 0.17). No difference in maximum OPS scores could be detected between the two study groups. The mean time to full recovery regarding sedation was 149 min and 153 min in groups C and I, respectively. CONCLUSIONS: This pilot study demonstrates a trend for better postoperative analgesia following peripheral administration of clonidine compared with central application. However, the main mechanism for the adjunct analgesic effect of clonidine when administered together with local anaesthetics requires further study.     

Alkalinisation of bupivacaine for sciatic nerve blockade

This double-blind study investigates the effect of pH adjustment of bupivacaine 0.5% with adrenaline 1:200,000 on block latency, duration of analgesia and systemic absorption of local anaesthetic after sciatic nerve blockade. Twenty-four adult patients were randomly allocated into one of two groups: Group A (n = 12) received bupivacaine with adrenaline 1:200,000 (pH 3.9) 2 mg/kg, while Group B (n = 12) received alkalinised bupivacaine with adrenaline 1:200,000 (pH 6.4) 2 mg/kg. Increasing the pH of the local anaesthetic solution significantly reduced block latency from 25 minutes in Group A to 12.5 minutes in Group B (p less than 0.001) and prolonged the duration of useful analgesia from 14.1 hours to 18.3 hours (p less than 0.001). There was no significant difference in plasma bupivacaine levels between the two groups. The results indicate that alkalinisation of bupivacaine reduces time to onset and prolongs the duration of useful analgesia when used for sciatic nerve blockade, without significantly increasing systemic absorption.     

Distal peripheral nerve blockade for patients undergoing hand surgery: a pilot study

BackgroundData are limited regarding the use of peripheral nerve blockade at the level of the forearm, and most studies regard these procedures as rescue techniques for failed or incomplete blocks. The purpose of the study was to investigate patients undergoing hand surgery with distal peripheral nerve (forearm) blocks and compare them with patients having similar procedures under more proximal brachial plexus blockade. No investigations comparing distal nerve blockade to proximal approaches are currently reported in the literature.MethodsMedical records were retrospectively reviewed for patients who had undergone hand surgery with a peripheral nerve block between November 2012 and October 2013. The primary outcome was the ability to provide a primary anesthetic without the need for general anesthesia or local anesthetic supplementation by the surgical team. Secondary outcome measures included narcotic administration during the block and intraoperative procedures, block performance times, and the need for rescue analgesics in the post anesthesia care unit (PACU).ResultsNo statistical difference in conversion rates to general anesthesia was observed between the two groups. Total opiate administration for the block and surgical procedure was lower in the forearm block group. There was no difference in block performance times or need for rescue analgesics in the PACU.ConclusionsForearm blocks are viable alternatives to proximal blockade and are effective as a primary anesthetic technique in patients undergoing hand surgery. Compared to the more proximal approaches, these blocks have the benefits of not causing respiratory compromise, the ability to be performed bilaterally, and may be safer in anticoagulated patients.     

The effect of oral dexamethasone on duration of analgesia after upper limb surgery under infraclavicular brachial plexus block: a randomised controlled trial

The effects of oral dexamethasone on peripheral nerve blocks have not been investigated. We randomly allocated adults scheduled for forearm or hand surgery to oral placebo (n = 61), dexamethasone 12 mg (n = 61) or dexamethasone 24 mg (n = 57) about 45 min before lateral infraclavicular block. Mean (SD) time until first pain after block were: 841 (327) min; 1171 (318) min; and 1256 (395) min, respectively. Mean (98.3%CI) differences in time until first postoperative pain for dexamethasone 24 mg vs. placebo and vs. dexamethasone 12 mg were: 412 (248–577) min, p < 0.001; and 85 (-78 to 249) min, p = 0.21, respectively. Mean (98.3%CI) difference in time until first postoperative pain for dexamethasone 12 mg vs. placebo was 330 (186–474) min, p < 0.001. Both 24 mg and 12 mg of oral dexamethasone increased the time until first postoperative pain compared with placebo in patients having upper limb surgery under infraclavicular brachial plexus block.     

High-dose bupivacaine, levobupivacaine and ropivacaine in axillary brachial plexus block

BACKGROUND: Racemic bupivacaine is clinically similar to levobupivacaine, or ropivacaine. The drugs were compared in brachial plexus block for the first time in the same randomized and double-blind study. METHODS: In 90 patients scheduled for hand and forearm surgery, a perivascular axillary brachial plexus block was performed with 45 ml of 5 mg ml(-1) of either racemic bupivacaine-HCl, levobupivacaine-HCl, or ropivacaine-HCl. Sensory (cold) and motor (hand clasp, and movement of elbow) block were scored, and the patient was interviewed in the postoperative evening and the following morning. Time to normal function of the arm was registered. RESULTS: After similar onsets of sensory block, the sum of completely anaesthetized innervation areas of the four main nerves at 45 min was greater in the ropivacaine group than in the levobupivacaine group (P < 0.01). Simultaneously, complete motor block at the elbow was more frequent in the ropivacaine group (67%) than in the bupivacaine (47%) and levobupivacaine groups (30%) (P < 0.01). In the hand, the corresponding results were 83%, 77%, and 57%, respectively (NS). Two patients in the levobupivacaine and one in the ropivacaine group needed general anaesthesia. Mean duration of the blocks was similar in the bupivacaine, levobupivacaine and ropivacaine groups at 19.3 h, 19.5 h, and 17.3 h, respectively (NS). Two patients were dissatisfied with the long block duration. CONCLUSION: Ropivacaine-HCl 5 mg ml(-1) produced slightly better sensory and motor block intensity than the same dose of levobupivacaine-HCl. General success in relation to surgery and in the duration of the blocks was similar in the three groups.     

Surface mapping of peripheral nerves in children with a nerve stimulator

Defining anatomical landmarks may be difficult in the growing child. With the aid of a peripheral nerve stimulator, the path of many superficial peripheral nerves can be 'mapped' prior to skin penetration by stimulating the motor component of the peripheral nerve percutaneously with a 2-3.5 mA output. The required current will vary and is dependent upon the depth of the nerve and the moistness of the overlying skin. This 'nerve mapping technique' has proved particularly useful for brachial plexus, axillary, ulna and median nerve blocks in the upper limb and femoral and popliteal nerve blocks in the lower limb. It is a useful teaching tool and improves the success rate of peripheral nerve blocks in children of all ages.     

Microcirculation and haemodynamics after infraclavicular brachial plexus block using adrenaline as an adjuvant to lidocaine: a randomised,double-blind,crossover study in healthy volunteers

We evaluated the effect of adrenaline on human skin microcirculation (nutritive and sub-papillary) and systemic cardiovascular variables after it was added to lidocaine in infraclavicular brachial plexus blocks. Twelve healthy, non-smoking male volunteers were included, each attending two study sessions 2 weeks apart, and they were studied using a crossover design. In both sessions, they received an ultrasound-guided infraclavicular brachial plexus block in the non-dominant arm with 0.4 ml.kg⁻¹ lidocaine, 15 mg.ml⁻¹ with or without adrenaline 5 μg.ml⁻¹. Microcirculation was assessed by laser Doppler fluxmetry (sub-papillary blood flow), capillary video microscopy (nutritive blood flow) and continuous temperature measurements. Heart rate and arterial pressure were recorded continuously and non-invasively. Median (IQR [range]) sub-papillary blood flow increased substantially 30 min after the brachial plexus block, from 8.5 (4.4–13.5 [2.9–28.2]) to 162.7 (111.0–197.8 [9.5–206.7]) arbitrary units with adrenaline (p = 0.017), and from 6.9 (5.3–28.5 [1.8–42.1] to 133.7 (16.5–216.7 [1.0–445.0] arbitrary units without adrenaline (p = 0.036). Nutritive blood flow (functional capillary density, capillaries.mm⁻², measured at the dorsal side of the hand) decreased in the blocked extremity when adrenaline was used as adjuvant, from median (IQR [range]) 45 (36–52 [26–59]) to 38 (29–41 [26–42]), p = 0.028, whereas no significant change occurred without adrenaline. Median finger skin temperature (°C) increased by 44% (data pooled) with no significant differences between the groups. No significant changes were found in the systemic cardiovascular variables with or without adrenaline. We conclude that lidocaine infraclavicular brachial plexus blocks caused an increase in skin sub-papillary blood flow. The addition of adrenaline produced stronger and longer lasting blocks, but decreased the nutritive blood flow.     

The alkalinisation of bupivacaine for intercostal nerve blockade

A double-blind randomised study was performed to investigate the effect of pH adjustment of bupivacaine, with adrenaline 1:200,000, on the duration of block and pain relief after intercostal nerve blockade following thoracotomy. One group (n = 10) received bupivacaine with adrenaline 1:200,000 (pH = 4.1) and the other (n = 10) received alkalinised bupivacaine with adrenaline 1:200,000 (pH = 6.9). There was no significant difference in block duration (mean 23.9 and 26.4 hours respectively) visual analogue pain scores or morphine usage. Patients were more likely to have a block during the first 12 hours if they received alkalinised bupivacaine (p less than 0.01, Chi-squared test). A progressive regression of block, not previously described, was observed, explicable by means of spread of local anaesthesia to adjacent intercostal nerves. Alkalinisation of bupivacaine with adrenaline for intercostal nerve blockade has little clinical benefit.     

A randomised controlled trial of intravenous dexmedetomidine added to dexamethasone for arthroscopic rotator cuff repair and duration of interscalene block

Prolongation of peripheral nerve blockade by intravenous dexamethasone may be extended by intravenous dexmedetomidine. We randomly allocated 122 participants who had intravenous dexamethasone 0.15 mg.kg⁻¹ before interscalene brachial plexus block for day-case arthroscopic rotator cuff repair to intravenous saline (62 participants) or intravenous dexmedetomidine 1 μg.kg⁻¹ (60 participants). The primary outcome was time from block to first oral morphine intake during the first 48 postoperative hours. Fifty-nine participants reported taking oral morphine, 25/62 after placebo and 34/60 after dexmedetomidine, p = 0.10. The time to morphine intake was shorter after dexmedetomidine, hazard ratio (95%CI) 1.68 (1.00–2.82), p = 0.049. Median (IQR [range]) morphine doses were 0 (0–12.5 [0–50]) mg after control vs. 10 (0–30 [0–50]) after dexmedetomidine, a difference (95%CI) of 7 (0–10) mg, p = 0.056. There was no effect of dexmedetomidine on pain at rest or on movement. Intra-operative hypotension was recorded for 27/62 and 50/60 participants after placebo vs. dexmedetomidine, respectively, p < 0.001. Other outcomes were similar, including durations of sensory and motor block. In conclusion, dexmedetomidine shortened the time to oral morphine consumption after interscalene block combined with dexamethasone and caused intra-operative hypotension.     

Using psychometric ability to improve education in ultrasound-guided regional anaesthesia: a multicentre randomised controlled trial

The learning curve for novices developing regional anaesthesia skills, such as real-time ultrasound-guided needle manipulation, may be affected by innate visuospatial ability, as this influences spatial cognition and motor co-ordination. We conducted a multinational randomised controlled trial to test if novices with low visuospatial ability would perform better at an ultrasound-guided needling task with deliberate practice training than with discovery learning. Visuospatial ability was evaluated using the mental rotations test-A. We recruited 140 medical students and randomly allocated them into low-ability control (discovery learning), low-ability intervention (received deliberate practice), high-ability control, and high-ability intervention groups. Primary outcome was the time taken to complete the needling task, and there was no significant difference between groups: median (IQR [range]) low-ability control 125 s (69–237 [43–600 s]); low-ability intervention 163 s (116–276 [44–600 s]); high-ability control 130 s (80–210 [41–384 s]); and high-ability intervention 177 s (113–285 [43–547 s]), p = 0.06. No difference was found using the global rating scale: mean (95%CI) low-ability control 53% (95%CI 46–60%); low-ability intervention 61% (95%CI 53–68%); high-ability control 63% (95%CI 56–70%); and high-ability intervention 66% (95%CI 60–72%), p = 0.05. For overall procedure pass/fail, the low-ability control group pass rate of 42% (14/33) was significantly less than the other three groups: low-ability intervention 69% (25/36); high-ability control 68% (25/37); and high-ability intervention 85% (29/34) p = 0.003. Further research is required to determine the role of visuospatial ability screening in training for ultrasound-guided needle skills.     

地塞米松联合罗哌卡因用于老年髋部骨折患者术前镇痛的临床效果

目的：探讨地塞米松联合罗哌卡因用于超声引导下髋关节囊周围神经阻滞在术前老年髋部骨折患者镇痛中的应用。方法：选取2017年1月—2022年3月到我院就诊的老年髋部骨折患者103例,采用随机数字表法分为对照组（n=51）与治疗组（n=52）,两组患者在腰麻前均进行超声引导下髋关节囊周围神经阻滞,对照组注射0.5%的罗哌卡因,治疗组注射0.5%的罗哌卡因+8 mg地塞米松。观察比较术后6 h、12 h、24 h、48 h患者分别于静息状态、运动状态时的NRS疼痛评分、两组患者的术后情况（住院时间、下床时间、镇痛药物使用次数及首次按压镇痛泵时间）、两组患者术后并发症发生情况（心律失常、穿刺血肿、恶心呕吐、神经损伤等）。结果：治疗组静息状态和运动状态时6 h、12 h、24 h、48 h的NRS评分均低于对照组,差异有统计学意义（P <0.05）,术后治疗组患者住院时间、下床时间、镇痛药物使用次数均低于对照组,差异有统计学意义（P <0.05）,首次按压镇痛泵时间长于对照组,差异有统计学意义（P <0.05）。治疗组患者术后心律失常、穿刺血肿、恶心呕吐、神经损伤等并发症发生率为...     

Feasibility of ultrasound-guided peripheral nerve block catheters for pain control on pediatric medical missions in developing countries

Continuous peripheral nerve blocks (CPNB) are effective for postoperative pain management in children in the hospital and at home. CPNB techniques are particularly advantageous when compared with systemic or oral opioids on medical missions to unfamiliar environments with minimal monitoring capacity. In addition, ultrasound-guidance facilitates the placement of perineural catheters in anesthetized children even in the absence of commercially packaged regional anesthesia equipment. We present a series of successful cases employing ultrasound-guided CPNB for postoperative analgesia on medical missions and discuss the impact of this technology on present and future patients in underserved countries.