Ropivacaine or 2% mepivacaine for lower limb peripheral nerve blocks. Study Group on Orthopedic Anesthesia of the Italian Society of Anesthesia, Analgesia, and Intensive Care

BACKGROUND: Intra- and postoperative clinical properties of sciatic-femoral nerve block performed with either ropivacaine at different concentrations or mepivacaine have been evaluated in a multicenter, randomized, blinded study. METHODS: Adult patients scheduled for foot and ankle surgery were randomized to receive combined sciatic-femoral nerve block with 225 mg of either 0.5% (n = 83), 0.75% (n = 87), or 1% (n = 86) ropivacaine, or with 500 mg of 2% mepivacaine (n = 84). A thigh tourniquet was used in all patients. Onset time, adequacy of surgical anesthesia, time to offset of nerve block, and time until first postoperative requirement for pain medication were evaluated by a blinded observer. RESULTS: The adequacy of nerve block was similar in the four treatment groups (the ratios between adequate:inadequate: failed blocks were 74:9:0 with 0.5% ropivacaine, 74:13:0 with 0.75% ropivacaine, 78:8:0 with 1% ropivacaine, and 72:12:0 with 2% mepivacaine). The onset of the block was slower with 0.5% ropivacaine than with other anesthetic solutions (P < 0.001). Regardless of the concentration, ropivacaine produced a longer motor blockade (10.5+/-3.8 h, 10.3+/-4.3 h, and 10.2+/-5.1 h with 0.5%, 0.75%, and 1% ropivacaine, respectively) than with mepivacaine (4.3+/-2.6 h; P < 0.001). The duration of postoperative analgesia was shorter after mepivacaine (5.1+/-2.7 h) than after ropivacaine (12.2+/-4.1 h, 14.3+/-5 h, and 14.5+/-3.4 h, with 0.5%, 0.75%, or 1% ropivacaine, respectively; P < 0.001). Pain relief after 0.5% ropivacaine was 14% shorter than 0.75% or 1% ropivacaine (P < 0.05). During the first 24 h after surgery, 30-37% of patients receiving ropivacaine required no analgesics compared with 10% of those receiving mepivacaine (P < 0.001). CONCLUSIONS: This study suggests that 0.75% ropivacaine is the most suitable choice of local anesthetic for combined sciatic-femoral nerve block, providing an onset similar to mepivacaine and prolonged postoperative analgesia.     

What is the minimum effective volume of local anesthetic required for sciatic nerve blockade? A prospective, randomized comparison between a popliteal and a subgluteal approach

For sciatic nerve blockade, no study has defined the optimal volume of local anesthetic required to block the nerve. The current, prospective, randomized investigation was designed to find a minimum volume of 1.5% mepivacaine required to block the sciatic nerve using the subgluteal and posterior popliteal approaches. A total of 56 patients undergoing foot surgery were randomly assigned to receive sciatic nerve block by means of a posterior subgluteal (group subgluteal, n = 28) or a posterior popliteal (group popliteal, n = 28) approaches. All blocks were performed with the use a nerve stimulator (stimulating frequency, 2 Hz, intensity 1.5-0.5 mA) and a perineural stimulating catheter. In all patients, plantar flexion of the foot was elicited at <0.5 mA, to maintain consistency among groups. The volume of local anesthetic used in each patient was based on the modified Dixon's up-and-down method. Complete anesthesia was defined as complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot 20 min after injection. The mean volume of local anesthetic required to block the sciatic nerve was 12 +/- 3 mL in the subgluteal group and 20 +/- 3 mL in the popliteal group (P < 0.05). The ED95 for adequate block of the sciatic nerve was 17 mL in the subgluteal group and 30 mL in the popliteal group. The authors conclude that a larger volume of local anesthetic is necessary to block the sciatic nerve at a more distal site (popliteal approach) as compared with a more proximal level (subgluteal approach).     

Three-in-one blocks with ropivacaine: evaluation of sensory onset time and quality of sensory block

The purpose of this prospective, randomized, double-blinded study was to evaluate the sensory onset time and the quality of sensory block of ropivacaine, a new long-acting local anesthetic, compared with bupivacaine, for 3-in-1 blocks. Fifty ASA physical status I-III patients undergoing hip surgery after trauma were randomly assigned to two study groups of 25 patients each. The two study groups received a 3-in-1 block with either 20 mL of ropivacaine 0.5% or 20 mL of bupivacaine 0.5%. Blocks in both groups were performed using a nerve stimulator. The sensory onset time and the quality of sensory block was assessed by pinprick test in the central sensory region of each of the three nerves and compared with the same stimulation in the contralateral leg. We used a scale from 100% (normal sensation) to 0% (no sensory sensation). We did not find significant differences in sensory onset times between the ropivacaine group and the bupivacaine group (30+/-11 vs 32+/-10 min). The quality of sensory blocks was also comparable between the study groups (19%+/-20% vs 21%+/-15%). We conclude that the sensory onset time and quality of sensory block during 3-in-1 blocks performed with ropivacaine are comparable to those with bupivacaine. Ropivacaine is described as being less potent than bupivacaine, making this local anesthetic promising for 3-in-1 blocks because of its reportedly lower incidence of cardiovascular and central nervous system complications. IMPLICATIONS: Ropivacaine 0.5% has a sensory onset time and quality of sensory block during 3-in-1 blocks similar to that of bupivacaine 0.5%. Ropivacaine is described as being less potent than bupivacaine, making it a promising local anesthetic for 3-in-1 blocks because of its reportedly lower cardiovascular and central nervous system toxicity.     

Blocks at the wrist provide effective anesthesia for carpal tunnel release

PURPOSE: Distal blocks are not recommended even for a short procedure when a tourniquet is used. This study was designed to evaluate the tolerance, effectiveness, patient acceptance and safety of distal blocks at the wrist. METHODS: Consecutive patients (n=273, mean age 53 +/-15 yr) undergoing endoscopic carpal tunnel release with a pneumatic tourniquet were included in this study. The median nerve was blocked 6 cm above the wrist crease by injecting 10 mL of 2% lidocaine and 0.5% bupivacaine (v/v). The ulnar nerve was blocked by injecting 8 mL of the same anesthetic mixture below the flexor carpi ulnaris tendon 6 cm above the wrist crease. Finally, 2 mL of local anesthetic were infiltrated sc and laterally below the crease to block the musculocutaneous nerve. The intensity of the block was evaluated after five, ten and 20 min. In addition, pain associated with block performance and tolerance of the tourniquet were evaluated. Finally, neurological complications associated with this technique were investigated. Data are presented as means +/- SD. RESULTS: At ten minutes after the block was performed, 9% and 32% of patients required an additional injection to complete the block in the median and ulnar territories, respectively. In more than 75% of patients, performance of the block was associated with either no or mild pain. The tourniquet was inflated for 12.6 +/- 5.4 min and was well tolerated in 99% of patients. Finally, neither transient nor permanent neurological deficit were recorded postoperatively. CONCLUSION: Blocks at the wrist are effective, well accepted by the patient and safe when a pneumatic tourniquet is used for a short procedure.     

Interscalene brachial plexus block with continuous intraarticular infusion of ropivacaine

Providing intraarticular analgesia with a continuous infusion of local anesthetic via a disposable infusion pump has gained popularity. Despite the prevalence of this technique, data comparing this method of analgesia to conventional regional anesthesia are not available. We present a prospective study that compared a single-dose interscalene block with a single-dose interscalene block plus continuous intraarticular infusion of local anesthetic. Forty patients scheduled for shoulder arthroscopy were entered in this prospective, double-blinded study. All patients received an interscalene brachial plexus block as their primary anesthetic. Patients were randomly assigned to 1 of 2 groups: 1. interscalene block with 1.5% mepivacaine (40 mL) followed by a postoperative intraarticular infusion of 0.5% ropivacaine at 2 mL/h, or 2. interscalene block with 0.5% ropivacaine (40 mL) followed by a postoperative intraarticular infusion of 0.9% saline (placebo) at 2 mL/h. Postoperative infusions were maintained for 48 h. Visual analog scale pain scores and postoperative oxycodone consumption were measured for 48 h. Visual analog scale scores at rest and with ambulation in the Mepivacaine/Intraarticular Ropivacaine group were reduced when compared with the Ropivacaine/Saline group (rest: P = 0.003, ambulation: P = 0.006). Oxycodone consumption was also decreased (28 +/- 21 mg vs 44 +/- 28 mg, P = 0.046), respectively. We conclude that a brachial plexus block with 1.5% mepivacaine and a continuous intraarticular infusion of 0.5% ropivacaine at 2 mL/h provides improved analgesia for minor surgery at 24 and 48 h versus a single-injection interscalene block with 0.5% ropivacaine.     

Ultrasound guidance with nerve stimulation reduces the time necessary for resident peripheral nerve blockade

BACKGROUND AND OBJECTIVES: Educating residents in peripheral nerve blockade may impact the efficiency of a busy regional anesthesia service. Ultrasound guidance may affect the efficiency and effectiveness of nerve block. We examined the impact of ultrasound guidance on resident performance of peripheral nerve block in a regional anesthesia rotation. METHODS: An existing de-identified database was used for retrospective analysis of resident performance of interscalene, axillary, femoral, and popliteal nerve blocks, by peripheral nerve stimulator guidance alone and by nerve stimulator aided by ultrasound. The primary variable examined was the time required to perform the block. Others variables included (1) number of needle insertions; (2) proportion of blocks in which there was a blood vessel puncture; and (3) block efficacy. Peripheral nerve-stimulator blocks were guided by surface anatomy and motor stimulation, refined to 0.2 to 0.5 mA of current before injection of local anesthetic, while ultrasound nerve stimulator blocks were confirmed using a current of 0.5 mA. RESULTS: Ultrasound-aided blocks required less time to perform (median = 1.8 min) than nerve stimulator-guided blocks (median = 6.5 min, P < .001). More needle insertions were required for nerve localization in the nerve stimulator-guided blocks (median = 6) than in ultrasound-aided blocks (median = 2; P < .001). There were fewer blood vessel punctures with ultrasound-aided blocks (P = .03). CONCLUSIONS: During resident teaching, ultrasound-aided peripheral nerve-stimulated block required less time to perform than did nerve-stimulator-guided blocks. Fewer needle insertions were required to perform the ultrasound-guided blocks, and there were fewer blood vessel punctures when ultrasound was used.     

A comparison of two techniques for cervical plexus blockade: evaluation of efficacy and systemic toxicity

We compared two techniques of cervical plexus blockade (CPB) for carotid endarterectomy. Cervical plexus nerve block was performed with a combination of bupivacaine and lidocaine, with injections at the C2-C3, C3-C4, and C4-C5 transverse processes in 11 patients (classical CPB) or with a single injection after localization of the cervical plexus with a nerve stimulator in 12 patients (interscalene CPB). Pain scores were obtained during block placement and at predetermined phases of the operation. Arterial blood was sampled before and 3, 5, 8, 10, 15, 25, 40, and 60 min after CPB for measurement of bupivacaine and lidocaine concentrations. Interscalene CPB was less painful than classical CPB. The techniques appeared equally effective. Patients in both groups required equivalent supplementation with IV fentanyl and additional local infiltration with lidocaine during the most painful stages of surgery. The maximal concentration of bupivacaine was lower in interscalene CPB compared with classical CPB (1.0 microg/mL versus 1.5 microg/mL, P < 0.01). The time required to reach the maximal concentration of bupivacaine was 15 (10-40) min in interscalene CPB and 10 (5-17) min in classical CPB (P < 0.05). Lidocaine maximal concentration was similar in both groups, however the time required to reach the maximal concentration was longer (P < 0.05) in interscalene CPB (15 [10-60] min) than in classical CPB (10 [8-20] min). We conclude that the interscalene CPB is as effective as the classical CPB as a regional technique for carotid endarterectomy and may be associated with a lower systemic absorption of bupivacaine. IMPLICATIONS: Cervical plexus blockade for carotid endarterectomy can be effectively performed with a single injection after localization of the cervical plexus with a nerve stimulator. This technique is simple and was associated with less systemic absorption of local anesthetic than the multiple-injection technique.     

The supraclavicular block with a nerve stimulator: to decrease or not to decrease, that is the question

Portable nerve stimulators for nerve blocks have been available for more than 40 yr. It is generally accepted that seeking a motor response at low outputs increases the chances of success. It is customary to start the procedure at a higher current with the goal of finding the nerve. After an adequate response is elicited, the current is decreased before the local anesthetic is injected. However, how low is low enough and, for that matter, how high is too high have not been adequately determined. Our experience seems to indicate that, in the supraclavicular block, the type of response obtained is as important as the output at which it is elicited, provided that this current is not higher than 1 mA. In this context, it is theoretically possible that our initial seeking current of 0.9 mA could be an adequate injection current if it is combined with an appropriate response. We designed this study to test the hypothesis that a response of the fingers in flexion or extension, elicited at 0.9 mA, could be followed immediately by the local anesthetic injection. We did not intend to compare 0.5 and 0.9 mA as minimum stimulating currents but rather as currents able to elicit an unmistakable motor twitch. Sixty patients were randomly assigned to one of two groups. Group 1 (n = 30) was injected with a motor twitch in the fingers that was still visible at 0.5 mA. Group 2 (n = 30) was injected after a similar response to that in Group 1 was elicited, but at the initial output of 0.9 mA, without any further decrease. The blocks were injected with 40 mL of local anesthetic solution. One patient was excluded from the study for failing to meet protocol criteria. The success rate in the remaining 59 patients was 100%; success was defined as complete sensory blockade at the median, ulnar, and radial nerve territories of the hand that was accomplished in 相似文献   

Clonidine combined with a long acting local anesthetic does not prolong postoperative analgesia after brachial plexus block but does induce hemodynamic changes

Clonidine in brachial plexus block prolongs analgesia of local anesthetics of short and intermediate duration. We performed a prospective randomized double-blinded study to determine the efficacy and adverse effects of clonidine mixed with a long-acting local anesthetic on postoperative analgesia. Sixty adult patients underwent elective rotator cuff repair using interscalene brachial plexus block combined with general anesthesia and were randomly divided into one of the following three groups. Placebo (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine (1/200000) and 1 mL of 0.9% saline, completed by 1 mL of 0.9% saline IM in the controlateral shoulder; Control (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine and 1 mL of 0. 9% saline, completed by 150 microg (=1 mL) of clonidine IM; Clonidine (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine and 150 microg (=1 mL) of clonidine, completed by 1 mL of 0.9% saline IM. During anesthesia hemodynamic variables and fractional expired isoflurane concentration (FeISO) were recorded. The following postoperative variables were assessed: duration of interscalene block, quality of pain relief on a visual analog scale, side effects, and consumption of morphine with a patient-controlled analgesia device over 48 h. Patient characteristics were comparable. During anesthesia mean arterial pressure, heart rate, and FeISO were significantly decreased in Clonidine and Control groups compared with Placebo group. Duration of analgesia, defined as the time elapsed from interscalene injection to the first morphine request, was 983 +/- 489 min in the Placebo, 909 +/- 160 min in the Control, and 829 +/- 159 min in the Clonidine groups. Pain scores and consumption of morphine at 24 h and 48 h showed no differences among the three groups. We conclude that adding 150 microg of clonidine in interscalene block does not prolong analgesia induced by 40 mL of bupivacaine 0.5% with epinephrine, but decreases mean arterial blood pressure and heart rate. Implications: Clonidine in brachial plexus block does not improve postoperative analgesia when mixed with a long-lasting anesthetic. Nevertheless, with or without clonidine, bupivacaine in interscalene block provides a long-lasting analgesia of approximately 15 h.     

Successful interscalene block with a nerve stimulator may also result after a pectoralis major motor response

BACKGROUND AND OBJECTIVES: Interscalene block of the brachial plexus is a well-established anesthetic and analgesia technique for shoulder surgery. The endpoint for successful block using the nerve stimulator has been described by previous authors as a bicep motor response (twitch) and recently by a deltoid motor response. This retrospective observational case study of regular clinical practice examined the efficacy of using the pectoralis major motor response as an endpoint for a successful block. METHODS: A total of 120 patients who were scheduled for elective ambulatory shoulder surgery were retrospectively studied. All interscalene blocks were performed with aid of a nerve stimulator. Patients were categorized into 3 groups of 40 patients. Group 1 (biceps twitch), group 2 (deltoid twitch), and group 3 (pectoralis major twitch) were compared on success of the block. This retrospective study was conducted by reviewing interscalene block data sheets from the last 40 patients consecutively receiving interscalene block from either a bicep, deltoid, or pectoralis major motor response. A successful block was defined by the inability of the patient to raise their arm against gravity 20 minutes after injection of the local anesthetic. RESULTS: Pectoralis major motor response as an endpoint for local anesthetic injection was examined. Of 40 patients studied in this group, 38/40 were judged successful. This was comparable to the success rate in biceps (38/40 successful) and deltoid groups (37/40 successful). CONCLUSIONS: This retrospective observational case study of regular clinical practice suggests that a pectoralis major motor response can be a satisfactory endpoint for interscalene block.     

Ropivacaine or 2% Mepivacaine for Lower Limb Peripheral Nerve Blocks

Background: Intra- and postoperative clinical properties of sciatic-femoral nerve block performed with either ropivacaine at different concentrations or mepivacaine have been evaluated in a multicenter, randomized, blinded study.

Methods: Adult patients scheduled for foot and ankle surgery were randomized to receive combined sciatic-femoral nerve block with 225 mg of either 0.5% (n = 83), 0.75% (n = 87), or 1% (n = 86) ropivacaine, or with 500 mg of 2% mepivacaine (n = 84). A thigh tourniquet was used in all patients. Onset time, adequacy of surgical anesthesia, time to offset of nerve block, and time until first postoperative requirement for pain medication were evaluated by a blinded observer.

Results: The adequacy of nerve block was similar in the four treatment groups (the ratios between adequate:inadequate: failed blocks were 74:9:0 with 0.5% ropivacaine, 74:13:0 with 0.75% ropivacaine, 78:8:0 with 1% ropivacaine, and 72:12:0 with 2% mepivacaine). The onset of the block was slower with 0.5% ropivacaine than with other anesthetic solutions (P < 0.001). Regardless of the concentration, ropivacaine produced a longer motor blockade (10.5 +/- 3.8 h, 10.3 +/- 4.3 h, and 10.2 +/- 5.1 h with 0.5%, 0.75%, and 1% ropivacaine, respectively) than with mepivacaine (4.3 +/- 2.6 h; P < 0.001). The duration of postoperative analgesia was shorter after mepivacaine (5.1 +/- 2.7 h) than after ropivacaine (12.2 +/- 4.1 h, 14.3 +/- 5 h, and 14.5 +/- 3.4 h, with 0.5%, 0.75%, or 1% ropivacaine, respectively; P < 0.001). Pain relief after 0.5% ropivacaine was 14% shorter than 0.75% or 1% ropivacaine (P < 0.05). During the first 24 h after surgery, 30-37% of patients receiving ropivacaine required no analgesics compared with 10% of those receiving mepivacaine (P < 0.001).     

Minimum local anesthetic volume blocking the femoral nerve in 50% of cases: a double-blinded comparison between 0.5% ropivacaine and 0.5% bupivacaine

Recent studies demonstrated that ropivacaine was nearly 40% less potent than bupivacaine in the first stage of labor, but contrasting results have been reported. We, therefore, conducted a prospective, randomized, double-blinded study to determine the effects of the ropivacaine/bupivacaine potency ratio on the minimum volume of local anesthetic required to produce effective block of the femoral nerve in 50% of patients. Fifty adults premedicated with IV midazolam, 0.05 mg/kg, undergoing elective knee arthroscopy received femoral nerve blocks with a multiple-injection technique with a nerve stimulator (contractions of vastus medialis, vastus intermedius, and vastus lateralis were elicited with a 0.5-mA stimulating current). Patients randomly received either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n = 25). The anesthetic volume was decided according to Dixon's up-and-down method, starting from 12 mL and being equally divided among the three elicited twitches. Successful nerve block was loss of pinprick sensation in the femoral nerve distribution with concomitant block of the quadriceps muscle within 20 min after injection, as assessed by a blinded observer. Positive or negative responses determined a 3-mL decrease or increase for the next patient, respectively. According to the up-and-down sequences, the minimum local anesthetic volume providing successful nerve block in 50% of cases was 14 +/- 2 mL in the ropivacaine group (95% CI: 12-16 mL) and 15 +/- 2 mL (95% CI: 13-17 mL) in the bupivacaine group (P: = 0.155). We conclude that the volume of 0.5% ropivacaine required to produce effective block of the femoral nerve in 50% of patients is similar to that required when using 0.5% bupivacaine. Implications: Considering the risk for drug-related systemic toxicity, the equipotency ratio between ropivacaine and bupivacaine is crucial for daily practice. Despite the 40% reduction in the analgesic potency of ropivacaine reported during epidural analgesia for labor pain, results of this prospective, randomized, double-blinded study demonstrated that the same volume of 0.5% ropivacaine or 0.5% bupivacaine is required to produce an effective block of the femoral nerve in 50% of cases.     

Perioperative interscalene block versus intra-articular injection of local anesthetics for postoperative analgesia in shoulder surgery

BACKGROUND AND OBJECTIVES: Up to 70% of patients report moderate to severe pain after shoulder surgery, which can compromise early rehabilitation and functional recuperation. Postoperative shoulder pain control is improved with both interscalene block and intra-articular local anesthetic injection. The present study hypothesized that perioperative interscalene analgesia would offer pain control superior to perioperative intra-articular local anesthetics over the first 24 hours after surgery. METHODS: Sixty patients undergoing shoulder surgery were randomly assigned to 1 of 2 groups: group IS had interscalene block with catheter installation, while group IA received intra-articular local anesthetic, also with catheter installation. All patients received 3 local anesthetic injections: 0.25 mL/kg of 2% lidocaine with epinephrine 2.5 microg/mL immediately before and after surgery, and 0.25 mL/kg of 0.5% bupivacaine with epinephrine 2.5 microg/mL 1 hour after the end of surgery, after which the catheters were removed, and no further local anesthetics were administered. Postoperative pain at rest was evaluated in the postanesthesia care unit (PACU), 3 hours, 6 hours and 24 hours after surgery. The area under the 24 hour pain over time curve was calculated. Hydromorphone consumption in the PACU and over 24 hours was recorded. RESULTS: Pain scores (IS: 0.4 +/- 2 vs. IA: 4 +/- 3, P < .0001) and opioid consumption (IS: 0.7 mg +/- 1.4 vs. IA: 1.5 mg +/- 1.2, P = .02) were significantly higher in the PACU for group IA. However, neither the mean pain scores over the first day after surgery (IS: 5 +/- 2 vs. IA: 5 +/- 3; P = .4) nor 24-hour opioid consumption (IS: 4.4 mg +/- 2.8 vs. IA: 4.2 mg +/- 2.6; P = .4) were significantly higher in group IA. CONCLUSIONS: PACU measurements of immediate postoperative pain and narcotic consumption favor perioperative interscalene analgesia over intra-articular analgesia. This benefit does not translate into lower overall pain for the first 24 hours after surgery.     

Regional anesthesia does not increase the risk of postoperative neuropathy in patients undergoing ulnar nerve transposition.

The use of regional anesthetic techniques in patients with preexisting neuropathies has been widely debated. The possibility of needle- or catheter-induced trauma, local anesthetic toxicity, or neural ischemia during regional blockade may place patients with underlying mechanical, ischemic, or metabolic neurologic derangements at increased risk of progressive neural injury. We evaluated the safety of regional versus general anesthesia in patients with a preexisting ulnar neuropathy undergoing ulnar nerve transposition. All patients (n = 360) who underwent ulnar nerve transposition at the Mayo Clinic from 1985 to 1999 were retrospectively studied. A general anesthetic was performed in 260 (72%) patients. The remaining 100 (28%) patients received an axillary block, including 64 patients in whom an ulnar paresthesia or nerve stimulator motor response was elicited at the time of block placement. Patient characteristics, the severity of preoperative ulnar nerve dysfunction, and surgical variables were similar between groups. Anesthetic technique did not affect neurologic outcome (new or worsening pain, paresthesias, numbness, or motor weakness) immediately after surgery or at 2 or 6 wk after surgery. All six patients in the Axillary Block group who reported new or worsening neurologic symptoms after surgery had received bupivacaine in combination with either an ulnar paresthesia or motor response. By using logistic regression, bupivacaine was identified as an independent risk factor for worsening of ulnar nerve function compared with other local anesthetics. We conclude that axillary blockade is a suitable anesthetic technique for this procedure. IMPLICATIONS: The use of regional anesthetic techniques in patients with preexisting neuropathies has been widely debated. Theoretical concerns include the risk of progressive nerve damage from direct needle trauma or local anesthetic toxicity. This investigation, however, supports the safety of axillary blockade in patients with preexisting ulnar neuropathy undergoing ulnar nerve transposition.     

Applying ultrasound imaging to interscalene brachial plexus block

OBJECTIVE: Previous studies have examined ultrasound-assisted brachial plexus blocks, but few have applied this imaging technology to the interscalene region. We report a case of interscalene brachial plexus block using ultrasound guidance to show the clinical usefulness of this technology. CASE REPORT: A nerve stimulator-guided interscalene block was attempted for arthroscopic shoulder surgery but failed. Subsequent nerve localization was accomplished by ultrasound imaging using a high-frequency probe (5-12 MHz) and the Philips ATL HDI 5000 unit. Ultrasound showed nerves between the scalene muscles, block needle movement at the time of advancement, and local anesthetic spread during injection. Interscalene block was successful after 1 attempt of nerve localization and needle placement. CONCLUSIONS: Advanced ultrasound technology is useful for nerve localization and can generate brachial plexus images of high resolution in the interscalene groove, guide block needle placement and advancement in real time to targeted nerves, and assess adequacy of local anesthetic spread at the time of injection. Ultrasound imaging guidance can potentially improve success during interscalene brachial plexus block.     

A new technique of continuous interscalene nerve block

PURPOSE: To describes a technique of indwelling interscalene catheter placement and to evaluate its complications. METHODS: One hundred and twenty patients undergoing major shoulder surgery received interscalene nerve block (ISNB) and were studied in three groups. Group 1 ISNB using Winnie's technique; group 2 by Winnie's technique with nerve stimulator and group 3 by epidural needle and catheter technique with nerve stimulator. All patients received 20 mL bupivacaine 0.5% and group 3 patients received an additional bupivacaine 0.25% infusion. Diaphragmatic movements were measured sonographically on emergence from anesthesia. Complications were noted. A visual analogue scale (0-10) was used to assess pain four hours postoperatively. RESULTS: Mean ipsilateral diaphragmatic movements were 4+/-8, 14+/-11 and 18+/-8 mm (mean +/- SD) in groups 1, 2 and 3 respectively. This was less than contralateral movements in all three groups (P < 0.05). None of the patients in groups 2 and 3 reported postoperative pain. The block failed in 10% of group 1 patients. Complete ipsilateral phrenic nerve block occurred in 85% of the patients in group 1, 35% of group 2 and 20% of group 3 (P < 0.05). Ipsilateral recurrent laryngeal nerve paralysis occurred in 20% of the patients in group 1, 5% of group 2 and in none of the patients in group 3 (P < 0.05). Horner's syndrome was noted in group 1 (30%), group 2 (12%) but not in group 3. None of the catheters in group 3 patients dislodged after an average use of 2.8+/-2.1 days. CONCLUSIONS: Indwelling catheter placement into the brachial plexus sheath as described in this communication was effective and associated with few complications.     

Interscalene perineural ropivacaine infusion:a comparison of two dosing regimens for postoperative analgesia

BACKGROUND AND OBJECTIVS: A continuous interscalene nerve block with a perineural infusion of ropivacaine 0.2% at 8 mL/h has been shown to provide potent analgesia following moderately painful shoulder surgery. However, this high basal rate limits infusion duration for ambulatory patients who must carry the local anesthetic reservoir. We undertook this investigation to determine if the basal rate of an interscalene perineural ropivacaine infusion could be decreased by 50% with a concurrent 200% increase in patient-controlled bolus dose without compromising infusion benefits in ambulatory patients undergoing moderately painful orthopedic shoulder surgery. METHODS: Preoperatively, patients (n = 24) received an interscalene perineural catheter and nerve block. Intraoperatively, patients received a standardized general anesthetic. Postoperatively, patients were discharged home with a portable infusion pump delivering ropivacaine 0.2% (500 mL reservoir) with a basal rate of 8 mL/h and a 2 mL patient-controlled bolus available each hour ("8/2" group, n = 12) or a 4 mL/h basal rate and 6 mL bolus dose ("4/6" group, n = 12), delivered in a randomized, double-blinded manner. RESULTS: Patients in the 4/6 group had higher baseline pain scores only on postoperative day (POD) 2 (P =.011). However, these patients also experienced an increase in breakthrough pain incidence (5.8 boluses/d v 3.2, P =.035) and intensity ("worst" pain = 8/10 v 4/10, P <.05), sleep disturbances (2.0 v 0.0, P <.001), and a decrease in analgesia satisfaction (8 v 10, P =.003). Patients in the 8/2 group exhausted their local anesthetic reservoirs after a median of 61 hours, while the 4/6 group had a median of 131 mL remaining at infusion discontinuation after a median of 75 hours (P <.001). CONCLUSIONS: Following moderately painful ambulatory shoulder surgery, decreasing an interscalene perineural ropivacaine 0.2% basal rate from 8 to 4 mL/h provides similar baseline analgesia and lengthens infusion duration, but compromises other infusion benefits.     

Nerve Puncture and Apparent Intraneural Injection during Ultrasound-guided Axillary Block Does Not Invariably Result in Neurologic Injury

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 prospectively 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.     

Phrenic nerve block caused by interscalene brachial plexus block: effects of digital pressure and a low volume of local anesthetic.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block (ISB) is associated with phrenic block and diaphragmatic paralysis when high volumes (40-50 mL) of local anesthetic are injected. The goal of our study was to test if a low volume of local anesthetic administered while maintaining proximal digital pressure might more selectively block the brachial plexus and decrease the frequency of phrenic nerve block. METHODS: Twenty healthy patients undergoing ISB for orthopedic surgery of the upper extremity were randomly allocated to receive either 20 mL 1.5% mepivacaine while proximal digital pressure to the site of puncture was performed, or 40 mL 1.5% mepivacaine without digital pressure. Spirometry and clinical data were evaluated at baseline, 10, and 90 minutes after accomplishing the block and after the motor and sensory block resolved. Diaphragmatic excursion during deep inspiration was also evaluated 90 minutes after the block was performed, with the patient in the sitting position. RESULTS: Interscalene brachial plexus block produced diaphragmatic paralysis in all patients included in the study, as demonstrated by the pulmonary function testing and the chest radiograph. No significant differences were found in any of the parameters studied. At 10 minutes, baseline functional residual capacity had diminished by 34 +/- 10% in the 40 mL group and 37 +/- 13% in the 20 mL group. Maximum cephalad sensory dermatome level was also similar in both groups, being C 3 or above in all patients. Ipsilateral hemidiaphragmatic motion was similar in both groups (3.2 +/- 2.3 cm in the 40 mL group and 2.6 +/- 1.7 cm in the 20 mL group). However, in no case was dyspnea manifested. CONCLUSIONS: Decreasing the volume of local anesthetic and applying proximal digital pressure to the site of injection is not effective in reducing the cervical block spread and the frequency or intensity of diaphragmatic paralysis during interscalene ISB.     

The difficulties of ambulatory interscalene and intra-articular infusions for rotator cuff surgery: a preliminary report

PURPOSE: Rotator cuff repair may result in severe postoperative pain. We compared a continuous intra-articular infusion to a continuous interscalene block with ropivacaine for patients undergoing outpatient rotator cuff repair. METHODS: Seventeen patients were randomized to one of two groups: 1) interscalene block with 0.5% ropivacaine (40 mL) followed by a postoperative intra-articular infusion or; 2) interscalene block with 0.5% ropivacaine (40 mL) followed by a postoperative continuous interscalene infusion. Infusions were 0.2% ropivacaine at 10 mL x hr(-1) for both groups. Infusions were maintained for 48 hr. Patients were discharged on the day of surgery. Verbal analogue pain scores (VAS) and postoperative oxycodone consumption were measured for 48 hr. RESULTS: Eight patients (47%; four in each group) had side effects or logistical problems complicating care. The mean VAS scores at rest and with movement in the postanesthesia care unit and at 12 hr, 24 hr, and 48 hr were not different (P > 0.1). Inadequate analgesia was reported in 50-75% of all study patients. Time until first oxycodone use was similar between groups 829 min +/- 432 (interscalene) and 999 min +/- 823 (intra-articular; P = 0.6). Total oxycodone consumption was also similar 49 mg +/- 48 and 59 mg +/- 51 (P = 0.7), respectively. CONCLUSIONS: This study demonstrates the difficulties of ambulatory interscalene and intra-articular infusion for rotator cuff surgery. The high VAS scores and need for additional medical care suggest that intra-articular administration may not be reasonable for this magnitude of surgery. Further refinement of the perineural local anesthetic infusion is necessary to consistently provide analgesia after ambulatory rotator cuff surgery.