Article

Postoperative Analgesia After Peripheral Nerve Block for Podiatric Surgery: Clinical Efficacy and Chemical Stability of Lidocaine Alone Versus Lidocaine Plus Clonidine

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Abstract

Postoperative analgesia may be prolonged by the addition of clonidine to local anesthetic solutions used for regional anesthesia.The purpose of this study was to test this hypothesis in a clinical trial of patients undergoing podiatric surgery. The study design was prospective, double-blinded, and randomized. Ninety ASA physical status I or II patients scheduled for bunionectomy or hammer toe repair were randomized to receive ankle or metatarsal blocks with plain 1.73% lidocaine (Group L), 1.73% lidocaine with 10 micro gram/mL of clonidine added (Group C10), or 1.73% lidocaine with 20 micro gram/mL clonidine (Group C20). Time from the performance of the block to 1) loss of sensation to pinprick, 2) return of sensation to pinprick, 3) onset of postsurgical pain, and 4) time of first oral pain medication intake were recorded. Beginning at 1 h after the completion of the block, visual analog scale (VAS) and verbal pain scores were recorded every 30 min. Additional postoperative oral pain medication required in the first 9 h after the block was also recorded. Analysis of variance (ANOVA) was used to analyze intergroup differences in the VAS and verbal pain scores, the time to first reported pain, the time to first oral pain medication, and the total amount of oral pain medications required. Repeated-measures ANOVA was used to analyze the VAS and verbal pain scores overall and integrated assessment of pain scores and rescue medication was per-formed. Adverse events were also recorded for each group. There were no differences among the three groups with regard to overall VAS pain scores although Group C10 had significantly better verbal pain scores after the first 3 h (P < 0.05). There was also no difference in time to loss or return of pinprick sensation. Group C10 had a longer time to first reported pain (P < 0.01), a longer time to first oral pain medication (P < 0.01), a lower average total dose of oral pain medication required (P < 0.05), and a lower integrated assessment of pain and medication (P < 0.01) than Group L. More patients in Group C10 reported no pain postoperatively (P < 0.01) and no pain medication taken (P < 0.01) than Group L. Group C20 results suggested no statistically significant improvement over plain lidocaine. One patient in Group C20 experienced significant hypotension postoperatively. pH determinations and chemical analysis by capillary electrophoresis showed no significant change in composition of the solutions when clonidine was mixed with lidocaine and stored at 4 degrees C for 1 wk. Compared to 1.73% lidocaine, combining clonidine (10 micro gram/mL) with lidocaine for local anesthetic block for foot surgery significantly increases the duration and quality of postoperative analgesia. (Anesth Analg 1996;83:760-5)

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This randomized double-blind controlled trial compared the block characteristics of three low-dose local anesthetics at different roots in an ultrasound-guided interscalene block, using thermal quantitative sensory testing for assessing the functioning of cutaneous small nerve fibres. A total of 37 adults scheduled to undergo shoulder arthroscopy were randomized to receive 5 mL of either 0.5% levobupivacaine with and without epinephrine 1/200,000 or 0.75% ropivacaine in a single-shot interscalene block. Thermal quantitative sensory testing was performed in the C4, C5, C6 and C7 dermatomes. Detection thresholds for cold/warm sensation and cold/heat pain were measured before and at 30 min, 6, 10 and 24 h after infiltration around C5. The need for rescue medication was recorded. No significant differences between groups were found for any sensation (lowest P = 0.28). At 6 h, the largest differences in sensory thresholds were observed for the C5 dermatome. The increase in thresholds were less in C4 and C6 and minimal in C7 for all sensations. The analgesic effect lasted the longest in C5 (time × location mixed model P < 0.001 for all sensory tests). The time to rescue analgesia was significantly shorter with 0.75% ropivacaine (P = 0.02). The quantitative sensory findings showed no difference in intensity between the local anesthetics tested. A decrease in block intensity, with minimal changes in pain detection thresholds, was observed in the roots adjacent to C5, with the lowest block intensity in C7. A clinically relevant shorter duration was found with 0.75% ropivacaine compared to the other groups. Trial registration NCT 02691442.
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The current study was designed to test the hypothesis that high-dose dexmedetomidine added to local anesthetic would increase the duration of sensory and motor blockade in a rat model of sciatic nerve blockade without causing nerve damage. Thirty-one adult Sprague-Dawley rats received bilateral sciatic nerve blocks with either 0.2 ml bupivacaine, 0.5%, and 0.5% bupivacaine plus 0.005% dexmedetomidine in the contralateral extremity, or 0.2 ml dexmedetomidine, 0.005%, and normal saline in the contralateral extremity. Sensory and motor function were assessed by a blinded investigator every 30 min until the return of normal sensory and motor function. Sciatic nerves were harvested at either 24 h or 14 days after injection and analyzed for perineural inflammation and nerve damage. High-dose dexmedetomidine added to bupivacaine significantly enhanced the duration of sensory and motor blockade. Dexmedetomidine alone did not cause significant motor or sensory block. All of the nerves analyzed had normal axons and myelin at 24 h and 14 days. Bupivacaine plus dexmedetomidine showed less perineural inflammation at 24 h than the bupivacaine group when compared with the saline control. The finding that high-dose dexmedetomidine can safely improve the duration of bupivacaine-induced antinociception after sciatic nerve blockade in rats is an essential first step encouraging future studies in humans. The dose of dexmedetomidine used in this study may exceed the sedative safety threshold in humans and could cause prolonged motor blockade; therefore, future work with clinically relevant doses is necessary.
Article
To compare the sensory and motor effects of adding medetomidine to mepivicaine, administered either perineurally or systemically, for radial nerve block in dogs. Prospective randomized cross-over study. Six healthy Beagles, aged 18.7 +/- 6.3 months and weighing 10.4 +/- 1.3 kg. Dogs were anesthetized briefly with sevoflurane on three separate occasions and received each treatment administered in random order: mepivacaine 5 mg kg(-1) perineurally around the radial nerve with saline 0.01 mL kg(-1) intramuscularly (CONTROL); mepivacaine 5 mg kg(-1) and medetomidine 0.01 mg kg(-1) combined, perineurally with saline 0.01 mL kg(-1) intramuscularly (MEDPN); mepivacaine 5 mg kg(-1) perineurally around the radial nerve with medetomidine 0.01 mg kg(-1) intramuscularly (MEDIM). All nerve blocks were performed with the aid of a nerve locator. Motor effects were evaluated based on the ability to bear weight. Sensory effects were evaluated by the response to a graded-electrical stimulus. These were evaluated at 5-minute intervals for the first hour, and at 10-minute intervals thereafter. Mean intervals were calculated as follows: time to motor block onset, duration of motor block, time to peak sensory block, duration of peak sensory block (i.e. period of no response to maximal stimulus intensity), and duration of residual sensory block (i.e. time to return to baseline sensory function). Treatment means were compared using a one-way analysis of variance for repeated measures and, where significant differences were noted, a Student-Newman-Keuls test was applied; p < 0.05 was considered significant. Medetomidine, administered either systemically or perineurally, significantly prolonged duration of peak motor block, peak sensory block, and residual sensory block compared with CONTROL. Medetomidine prolonged sensory and motor blockade after radial nerve block with mepivacaine in dogs. Medetomidine may prove to be a useful adjunct to peripheral nerve blockade with local anesthetics.
Article
Pain may begin in the periphery with activation of nociceptor transducers. The present article reviews the pharmacology of drug action at the level of the primary afferent by discussing the following: [1] agents which block transduction processes (vanilloids, sodium ion channel blockers, antiserotonergic agents, antipurinergic agents); [2] agents inhibiting the transducer site (opioids, cannabinoids, alpha adrenergic agents); [3] agents blocking transducer-based modulation processes (anti-inflammatories, antikinin agents, antitachykinins); and [4] agents which block primary afferent-related modification processes (antineurotrophins). There is a clear role for many of these agents in the treatment of inflammatory pain and they have potential benefits for neuropathic pain with peripheral triggers.
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The admixture of clonidine or epinephrine to lidocaine for inferior alveolar nerve block was studied with regard to onset, duration, intensity of anaesthesia, postoperative analgesia, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), ST segment depression > or =1 mm and cardiac arrhythmias. Forty healthy patients (ASA I) received 2 ml 2% lidocaine with clonidine (15 microg/ml; n = 20) or epinephrine (12.5 microg/ml; n = 20) in a double-blind fashion for lower third molar surgery. Duration and intensity were not different between groups, while onset was significantly different by subjective evaluation. The need for postoperative pain medication was significantly lower in the clonidine group. There was a significant decrease in SBP and MAP in both groups 35 min after administration of anaesthesia compared with basal values, while DBP was significantly lower only in the clonidine group. There was no significant difference in SBP, DBP and MAP between groups. HR was significantly increased in the epinephrine group 5 min after administration of anaesthesia and during surgery compared with the clonidine group and with basal values. The presented data suggest that clonidine could be a useful and safe alternative to epinephrine for intraoral block anaesthesia.
Article
Background: Hallux valgus is classified as an abnormal deviation of the great toe (hallux) towards the midline of the foot. Objectives: To identify and evaluate the evidence from randomised trials of interventions used to correct hallux valgus. Search strategy: We searched the Cochrane Musculoskeletal Injuries Group trials register (2003/1), the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (January 1966 to March 2003) and EMBASE (1980 to January 2003). No language restrictions were applied. Hand searching of specific foot journals was also undertaken. Date of the most recent search: 31st March 2003. Selection criteria: Randomised or quasi-randomised trials of both conservative and surgical treatments of hallux valgus. Excluded were studies comparing areas of surgery not specific to the control of the deformity such as use of anaesthetics or tourniquet placement. Data collection and analysis: Methodological quality of trials which met the inclusion criteria was independently assessed by two reviewers. Data extraction was undertaken by two reviewers. The trials were grouped according to the interventions being compared, but the dissimilarity in the comparisons prevented pooling of results. Main results: The methodological quality of the 21 included trials was generally poor and trial sizes were small. Three trials involving 332 participants evaluated conservative treatments versus no treatment. There was no evidence of a difference in outcomes between treatment and no treatment. One good quality trial involving 140 participants compared surgery to conservative treatment. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving orthoses. The same trial also compared surgery to no treatment in 140 participants. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving no treatment. Two trials involving 133 people with hallux valgus compared Keller's arthroplasty with other surgical techniques. In general, there was no advantage or disadvantage using Keller's over the other techniques. When the distal osteotomy was compared to Keller's arthroplasty, the osteotomy showed evidence of improving the intermetatarsal angle and preserving joint range of motion. The arthroplasty was found to have less of an impact on walking ability compared to the arthrodesis. Six trials involving 309 participants compared chevron (and chevron-type) osteotomy with other techniques. The chevron osteotomy offered no advantages in these trials. For some outcomes, other techniques gave better results. Two of these trials (94 participants) compared a type of proximal osteotomy to a proximal chevron osteotomy and found no evidence of a difference in outcomes between techniques. Three trials involving 157 participants compared outcomes between original operations and surgeon's adaptations. There was no advantage found for any of the adaptations. Three trials involving 71 people with hallux valgus compared new methods of fixation to traditional methods. There was no evidence that the new methods of fixation were detrimental to the outcome of the patients. Four trials involving 162 participants evaluated methods of post-operative rehabilitation. The use of continuous passive motion appeared to give an improved range of motion and earlier recovery following surgery. Early weightbearing or the use of a crepe bandage were not found to be detrimental to final outcome. Reviewer's conclusions: Only a few studies had considered conservative treatments. The evidence from these suggested that orthoses and night splints did not appear to be any more beneficial in improving outcomes than no treatment. Surgery (chevron osteotomy) was shown to be beneficial compared to orthoses or no treatment, but when compared to other osteotomies, no technique was shown to be superior to any other. Only one trial had compared an osteotomy to an arthroplasty. There was limited evidence to suggest that the osteotomy gat the osteotomy gave the better outcomes. It was notable that the numbers of participants in some trials remaining dissatisfied at follow-up were consistently high (25 to 33%), even when the hallux valgus angle and pain had improved. A few of the more recent trials used assessment scores that combine several aspects of the patients outcomes. These scoring systems are useful to the clinician when comparing techniques but are of dubious relevance to the patient if they do not address their main concern and such scoring systems are frequently unvalidated. Only one study simply asked the patient if they were better than before the treatment. Final outcomes were most frequently measured at one year, with a few trials maintaining follow-up for 3 years. Such time-scales are minimal given that the patients will be on their feet for at least another 20-30 years after treatment. Future research should include patient-focused outcomes, standardised assessment criteria and longer surveillance periods, more usefully in the region of 5-10 years.
Article
This article focuses on regional anesthesia for orthopedic procedures of the lower extremity.
Article
Although clonidine has been shown to increase the duration of local anesthetic action and prolong postoperative analgesia when included in single-injection nerve blocks, a controlled investigation of the efficacy of this practice to improve analgesia for continuous perineural local anesthetic infusion has not been reported. In this study, ambulatory patients (n = 34) undergoing moderately painful upper extremity orthopedic surgery received an infraclavicular brachial plexus block (mepivacaine 1.5%, epinephrine 2.5 micro g/mL, and bicarbonate 0.1 mEq/mL) and a perineural catheter before surgery. After surgery, patients were discharged home with a portable infusion pump delivering either ropivacaine 0.2% or ropivacaine 0.2% plus clonidine 1 micro g/mL via the catheter for 3 days (basal, 8 mL/h; patient-controlled bolus, 2 mL every 20 min). Investigators and patients were blinded to random group assignment. Daily end-points included pain scores, patient-controlled bolus doses, oral analgesic use, sleep quality, and symptoms of catheter- or infusion-related complications. Adding clonidine to ropivacaine resulted in a statistically significant decrease in the number of self-administered 2-mL bolus doses on postoperative Days 0 and 1 (P < 0.02), but this decreased actual local anesthetic consumption by an average of only 2-7 mL/d (P < 0.02). There were no statistically significant differences between the two groups for any of the other variables investigated, including sleep quality or oral analgesic requirements. We conclude that adding 1 micro g/mL of clonidine to a ropivacaine infraclavicular perineural infusion does not provide clinically relevant improvements in analgesia, sleep quality, or oral analgesic requirements for ambulatory patients having moderately painful upper extremity surgery.
Article
The introduction of government-mandated standards for pain management has focused our attention on postoperative pain. With the recent JACHO standards' for ambulatory surgery, it is imperative that all health care workers who care for these patients are familiar with appropriate pain management. Developments in our understanding of the pathophysiology of acute pain have further enhanced our ability to improve pain management for postoperative ambulatory patients. This has led to the concept of preventive analgesia (inhibition of physiological and pathological secondary inflammatory pain). Extensive work has shown that this is best achieved using a multimodel approach usually consisting of an NSAID, opioid, and local anesthetic. NMDA antagonists (ketamine, dextromethorphan) and alpha-2 agnoists (clonodine) show potential supplements to further enhance pain management, especially if given preemptively. Nonpharmacological intervention such as cold therapy or acupuncture may also be considered. The armanentarium for effective pain management has improved substantially over the past few years. The challenge is for health care workers to implement these therapies to obtain optimum pain management in ambulatory surgical patients.
Article
Regional anesthesia (RA) is the anesthetic of choice for all foot and ankle surgery. Advances in anesthetic equipment and techniques have made peripheral nerve blocks the perfect anesthetic technique for these patients, who should be educated about them in their surgeon's office. The anesthetic alternative of choice is, in the authors' opinion, a neuraxial (i.e. spinal or subarachnoid) technique, rather than a general anesthesia (GA). GA has a higher morbidity and complication rate compared to RA. Performance of a peripheral nerve block, or PNB, requires proper training, equipment, and support personnel in order to handle any and all complications, including general anesthesia.
Article
Clonidine added to local anesthetics results in an increased duration of anesthesia or analgesia after brachial plexus block. We investigated the effect of selective application of clonidine to the median and musculocutaneous nerves during midhumeral block, a technique allowing selective nerve blocks with the use of different local anesthetics. Initially, 58 patients scheduled for hand surgery were prospectively enrolled to receive a midhumeral block. These patients were randomly allocated into two groups. The Control group (n = 28) received 10 mL of plain mepivacaine 1.5% for each nerve (median, musculocutaneous, ulnar, and radial). The Clonidine group (n = 30) received 10 mL of plain mepivacaine 1.5% for each nerve, but the median and musculocutaneous nerves also received a dose of 50 microg clonidine. One patient in the Control group and two patients in the Clonidine group with a failed block were therefore excluded from the analysis. The onset time of surgical anesthesia was recorded. The durations of sensory and motor blocks were checked every 15 min. The plasma mepivacaine concentration was analyzed from 10 patients in each group. Onset times for complete sensory block were similar between the two groups. Adding 50 microg clonidine to the median and musculocutaneous nerves resulted in a significant increase in the duration of sensory block in these nerves (P < 0.0001). Recovery of motor block was not different between the two groups. No significant difference was found between the two groups in the mean plasma mepivacaine concentration.
Article
Hallux valgus is classified as an abnormal deviation of the great toe (hallux) towards the midline of the foot. To identify and evaluate the evidence from randomised trials of interventions used to correct hallux valgus. We searched the Cochrane Bone, Joint and Muscle Trauama Group trials register (2003/1), the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (January 1966 to March 2003) and EMBASE (1980 to January 2003). No language restrictions were applied. Hand searching of specific foot journals was also undertaken.Date of the most recent search: 31st March 2003. Randomised or quasi-randomised trials of both conservative and surgical treatments of hallux valgus. Excluded were studies comparing areas of surgery not specific to the control of the deformity such as use of anaesthetics or tourniquet placement. Methodological quality of trials which met the inclusion criteria was independently assessed by two reviewers. Data extraction was undertaken by two reviewers. The trials were grouped according to the interventions being compared, but the dissimilarity in the comparisons prevented pooling of results. The methodological quality of the 21 included trials was generally poor and trial sizes were small.Three trials involving 332 participants evaluated conservative treatments versus no treatment. There was no evidence of a difference in outcomes between treatment and no treatment.One good quality trial involving 140 participants compared surgery to conservative treatment. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving orthoses. The same trial also compared surgery to no treatment in 140 participants. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving no treatment.Two trials involving 133 people with hallux valgus compared Keller's arthroplasty with other surgical techniques. In general, there was no advantage or disadvantage using Keller's over the other techniques. When the distal osteotomy was compared to Keller's arthroplasty, the osteotomy showed evidence of improving the intermetatarsal angle and preserving joint range of motion. The arthroplasty was found to have less of an impact on walking ability compared to the arthrodesis.Six trials involving 309 participants compared chevron (and chevron-type) osteotomy with other techniques. The chevron osteotomy offered no advantages in these trials. For some outcomes, other techniques gave better results. Two of these trials (94 participants) compared a type of proximal osteotomy to a proximal chevron osteotomy and found no evidence of a difference in outcomes between techniques.Three trials involving 157 participants compared outcomes between original operations and surgeon's adaptations. There was no advantage found for any of the adaptations.Three trials involving 71 people with hallux valgus compared new methods of fixation to traditional methods. There was no evidence that the new methods of fixation were detrimental to the outcome of the patients.Four trials involving 162 participants evaluated methods of post-operative rehabilitation. The use of continuous passive motion appeared to give an improved range of motion and earlier recovery following surgery. Early weightbearing or the use of a crepe bandage were not found to be detrimental to final outcome. Only a few studies had considered conservative treatments. The evidence from these suggested that orthoses and night splints did not appear to be any more beneficial in improving outcomes than no treatment. Surgery (chevron osteotomy) was shown to be beneficial compared to orthoses or no treatment, but when compared to other osteotomies, no technique was shown to be superior to any other. Only one trial had compared an osteotomy to an arthroplasty. There was limited evidence to suggest that the osteotomy gave the better outcomes. It was notable that the numbers of participants in some trials remaining dissatisfied at follow-up were consistently high (25 to 33%), even when the hallux valgus angle and pain had improved. A few of the more recent trials used assessment scores that combine several aspects of the patients outcomes. These scoring systems are useful to the clinician when comparing techniques but are of dubious relevance to the patient if they do not address their main concern and such scoring systems are frequently unvalidated. Only one study simply asked the patient if they were better than before the treatment. Final outcomes were most frequently measured at one year, with a few trials maintaining follow-up for 3 years. Such time-scales are minimal given that the patients will be on their feet for at least another 20-30 years after treatment. Future research should include patient-focused outcomes, standardised assessment criteria and longer surveillance periods, more usefully in the region of 5-10 years.
Article
In placebo-controlled acute surgical pain studies, provisions must be made for study subjects to receive adequate analgesic therapy. As such, most protocols allow study subjects to receive a pre-specified regimen of open-label analgesic drugs (rescue drugs) as needed. The selection of an appropriate rescue regimen is a critical experimental design choice. We hypothesized that a rescue regimen that is too liberal could lead to all study arms receiving similar levels of pain relief (thereby confounding experimental results), while a regimen that is too stringent could lead to a high subject dropout rate (giving rise to a preponderance of missing data). Despite the importance of rescue regimen as a study design feature, there exist no published review articles or meta-analysis focusing on the impact of rescue therapy on experimental outcomes. Therefore, when selecting a rescue regimen, researchers must rely on clinical factors (what analgesics do patients usually receive in similar surgical scenarios) and/or anecdotal evidence. In the following article, we attempt to bridge this gap by reviewing and discussing the experimental impacts of rescue therapy on a common acute surgical pain population: first metatarsal bunionectomy. The function of this analysis is to (1) create a framework for discussion and future exploration of rescue as a methodological study design feature, (2) discuss the interplay between data imputation techniques and rescue drugs, and (3) inform the readership regarding the impact of data imputation techniques on the validity of study conclusions. Our findings indicate that liberal rescue may degrade assay sensitivity, while stringent rescue may lead to unacceptably high dropout rates.
Article
The effect of adding clonidine to local anesthetics for nerve or plexus blocks remains unclear. The authors searched for randomized placebo-controlled trials testing the impact of adding clonidine to local anesthetics for peripheral single-injection nerve or plexus blocks in adults undergoing any surgery (except eye) without general anesthesia. Twenty trials (1,054 patients, 573 received clonidine) published 1992-2006 tested plexus (14 brachial, 1 cervical) and nerve blocks (2 sciatic/femoral, 1 midhumeral, 1 ilioinguinal/iliohypogastric, 1 ankle). Clonidine doses ranged from 30 to 300 microg; most patients received 150 microg. Clonidine prolonged the duration of postoperative analgesia (weighted mean difference 122 min; 95% confidence interval [CI] 74-169), sensory block (weighted mean difference 74 min; 95% CI 37-111), and motor block (weighted mean difference 141 min; 95% CI 82-199). In a subgroup of patients receiving an axillary plexus block, these effects were independent of whether clonidine was added to an intermediate or a long-acting local anesthetic. Clonidine increased the risk of arterial hypotension (odds ratio 3.61; 95% CI 1.52-8.55; number-needed-to-harm 11), orthostatic hypotension or fainting (odds ratio 5.07; 95% CI 1.20-21.4; number-needed-to-harm 10), bradycardia (odds ratio 3.09; 95% CI 1.10-8.64; number-needed-to-harm 13), and sedation (odds ratio 2.28; 95% CI 1.15-4.51; number-needed-to-harm 5). There was a lack of evidence of dose-responsiveness for beneficial or harmful effects. Clonidine added to intermediate or long-acting local anesthetics for single-shot peripheral nerve or plexus blocks prolongs duration of analgesia and motor block by about 2 h. The increased risk of hypotension, fainting, and sedation may limit its usefulness. Dose-responsiveness remains unclear.
Block of the five nerves supplying the foot, performed slightly proximal or distal to the level of the malleoli, is a simple, safe, and reliable technique that does not require patient cooperation, elicitation of paresthesia, or the use of a nerve stimulator. It can provide anesthesia for any type of foot surgery, thus avoiding the potential complications of general anesthesia or neuraxial block. Ankle block can also supply long lasting analgesia without motor block, allowing early ambulation. Modifications to the original technique, which consist of blocking the deep peroneal and posterior tibial nerves more distally where they are more superficial, have improved the success rate of the ankle block dramatically. By using a technique in which, after the initial injection, subsequent injections are made through previously anesthetized areas, patient discomfort during the placement of the block is minimal. When a tourniquet is required, placement at the ankle is effective, safe, and well tolerated.
Article
Surgery of the shoulder, elbow, and hand can cause considerable pain. According to data from randomized controlled trials, local or regional anesthesia is recommended for analgesia during and after surgery of the upper extremity. This treatment can be supplemented with potent opioids and nonsteroidal anti-inflammatory drugs in a multimodal analgesia approach. According to a metaanalysis of randomized controlled trials, an interscalene block is recommended for analgesia during and after surgery of the shoulder. For the elbow joint, a peripheral block is also recommended to allow for effective analgesia and physiotherapy postoperatively. In addition, cooling and physiotherapeutic techniques are beneficial in postoperative management.
Article
Objective: To determine whether bupivacaine peripheral nerve block of the saphenous, tibial and common peroneal nerves proximal to the femoro-tibial joint reduces peri-operative pain following extracapsular surgical stabilization of cranial cruciate ligament rupture in the nonchondrodystrophoid dog. Animals: Forty-one dogs with naturally acquired femoro-tibial joint instability. Study design Randomized, controlled, clinical trial. Methods: Dogs diagnosed with suspected cranial cruciate ligament injury based on physical and radiographic evidence were randomly assigned to treatment (bupivacaine) or control (saline) nerve blocks before femoro-tibial joint surgery. Pain scores, skin sensation, pain threshold to incisional pressure, time to first systemic 'rescue' opioid analgesic and total analgesic dose were evaluated for 24 hours. p < 0.05 was considered significant. Results: Treatment dogs had a significantly longer period of cutaneous desensitization than control dogs. There were no significant differences between treatment and control groups for pain score, pain threshold to incisional pressure, or time to first-rescue analgesic. The treatment group received significantly more supplemental analgesics than the control group. Conclusions: These peripheral nerve blocks were easy to perform and resulted in significant desensitization of the associated nerve autonomous zones, but did not improve post-operative analgesia. Clinical relevance: Clinical benefit was not detected when using this technique for peri-operative pain management following extracapsular cranial cruciate ligament surgical stabilization.
Article
Objective To document simple and reliable local, infiltrating nerve blocks for the saphenous, tibial and common peroneal nerves in the dog. Study design Laboratory technique development; in vivo blind, controlled, prospective study. Animals Twenty canine cadavers and 18 clinically normal, client-owned dogs. Methods A peripheral nerve blockade technique of the tibial, common peroneal, and saphenous nerves was perfected through anatomic dissection. Injections were planned in the caudal thigh for the tibial and common peroneal nerves, and in the medial thigh for the saphenous nerve. Cadaver limbs were injected with methylene blue dye and subsequently dissected to confirm successful dye placement. Clinically normal dogs undergoing general anesthesia for unrelated, elective procedures were randomly assigned to treatment (bupivacaine; n = 8) or control (saline; n = 8) nerve blocks of the nerves under study. Upon recovery from general anesthesia, skin sensation in selected dermatomes was evaluated for 24 hours. Results Cadaver tibial, common peroneal, and saphenous perineural infiltrations were successful in nonchondrodystrophoid dogs (100, 100, and 97%, respectively.) Intraneural injection was rare (1%; 1/105; tibial nerve) in cadaver dogs. In the treatment group of normal dogs, duration of loss of cutaneous sensation in some dermatomes (saphenous, superficial and deep peroneal nerve) was significantly different than control dogs; the range of desensitization occurred for 1–20 hours. No clinical morbidity was detected. Conclusions This technique for local blockade of the tibial, common peroneal, and saphenous nerves just proximal to the stifle is easy to perform, requires minimal supplies and results in significant desensitization of the associated dermatomes in clinically normal, nonchondrodystrophoid dogs. Clinical relevance This technique may be an effective tool for post-operative analgesia to the femoro-tibial joint and distal pelvic limb. Other applications, using sustained-release drugs or methods, may include anesthesia/analgesia in high-risk patients or as a treatment for chronic pelvic limb pain or self-mutilation.
The peripheral location of the surgical site in foot and ankle surgery and the possibility to block the pain pathways at multiple levels present a clear advantage of regional anesthesia in this setting. Several highly efficacious regional anesthesia techniques can be used to provide excellent operating conditions and low incidence of perioperative complications. Regional anesthesia techniques are also well suited for management of postoperative pain after foot and ankle surgery. In order to deliver anesthesia in a safe, efficient, and competent manner, the selection of a regional anesthetic must be based on the site, degree, and duration of the operation, requirement for ambulation, and on the requirement for pain control in the postoperative period. In this review we discuss some anatomic considerations for proper selection of regional anesthesia techniques for foot and ankle surgery and describe some new peripheral nerve blockade techniques suitable for these operations.
Introduction of continuous regional analgesia has resulted in improved quality of pain relief to patients and reduced the chances of unplanned admission in ambulatory surgical patients. Ambulatory patient controlled regional analgesia at home has further extended the use of regional analgesia beyond the hospital setting. The challenges posed by such ventures has resulted in development of newer techniques to reduce secondary catheter failures as well as adjuvants to local anesthesia that improve success with such novel modalities of pain relief. These include stimulating catheters, disposable infusion devices with patient controlled modalities and use of drugs such as ketamine and long acting local anesthetic formulations. There is further data available with regards to the safety of these techniques.
Besides that of the well-established centrally mediated anti-nociceptive effects of opioids, there is new evidence arising from the field of pain research and pain therapy indicating a peripherally mediated anti-nociception by these compounds and others, for which only a central site of analgesic action had previously been established. Focusing on α2-adrenoceptor agonists, this review will summarize some of the recent progress in this field and attempt to provide a rationale for a peripheral route of α2-adrenoreceptor agonist administration in specific clinical situations.
Article
SUMMARY A multitude of studies have focused on individual additives to local anesthetics and their effect on quality, onset, duration, spread and selectivity, as well as the potential toxic effects of their use. This review aims to give a broad overview of the current evidence in this developing field, based on beneficial and adverse effects of these drugs. We discuss the limitations of the available data and hope to convey implications and future perspectives for clinicians and researchers alike.
Article
The local anaesthetic and haemodynamic parameters achieved by lidocaine with clonidine or epinephrine, administered for maxillary infiltration anaesthesia, were studied in 40 patients (American Society of Anesthesiologists, physical status 1) who underwent upper third molar surgery. All patients received 2 ml of 2% lidocaine with clonidine (15 microg/ml; n=20) or epinephrine (12.5 microg/ml; n=20) in a randomized, double-blind fashion. Vascular effects were evaluated on the isolated human infraorbital arteries. The parameters of maxillary infiltration anaesthsia produced by a combination of lidocaine+clonidine were similar to those obtained with lidocaine+epinephrine. In both groups, haemodynamic parameters exhibited similar variations, with the exception of a significant reduction in heart rate and systolic blood pressure in the lidocaine+clonidine group and significant increase in heart rate in the lidocaine+epinephrine group, 10 min after surgery. Clonidine (10(-7), 10(-6) and 10(-5)M) produced an endothelium-independent vasocontractile effect on the isolated human infraorbital arteries. The results of this study indicate for the first time in dental anaesthesia that the lidocaine+clonidine combination could be a useful and safe alternative to lidocaine+epinephrine for intraoral infiltration anaesthesia.
Article
alpha(2)-Adrenoceptor agonists have an immensely diverse utility in peri-operative and critical care medicine. In particular, their application as premedicants, analgesics and hypnotics/sedatives is becoming increasingly popular with delivery to a wide spectrum of patients. The ability of these agents to provide renal, cardiac and neurocognitive protection is only just being realized and requires further study.
Article
With the continued use of alpha-2-adrenergic agonists in anesthetic practice, careful attention should be given to the potential for drug interactions. Based on a review of the basic and applied pharmacology of this class of compound, we have made recommendations for the safe and efficacious use of alpha-2-adrenergic agonists in the clinical setting.
Article
We examined local anesthetic effects of clonidine and its interaction with lidocaine with regard to tonic inhibition of the C-fiber action potential (AP) on the isolated, desheathed rabbit vagus nerve by the sucrose gap method. Clonidine and lidocaine at 500 microM concentrations caused a comparable degree of C-fiber inhibition, corresponding to an AP area under the curve of 75.8% +/- 9.4% (mean +/- SE) and 82.2% +/- 5.9% of control, respectively. Concentrations of clonidine less than 500 microM did not inhibit C-fiber AP. Clonidine, added in concentrations of 500 nM, 500 microM, and 5 mM to a 500 microM lidocaine perfusion, caused a significant decrease in fiber blockade of 18%, 20%, and 54%, respectively, as compared with clonidine added to Locke perfusion (P less than 0.05). The sodium channel blocker tetrodotoxin (3 microM) decreased the AP area to 9.3% +/- 1.3% of control. The remaining tetrodotoxin-resistant AP was almost completely blocked by clonidine (500 microM) and lidocaine (500 microM), indicating a higher susceptibility of tetrodotoxin-resistant fibers to the two drugs than the C-fiber population as a whole. The enhancing effect of a low dose of clonidine (500 nM) on lidocaine-induced (500 microM) inhibition of C-fiber AP might explain the clinical observation that clonidine, at approximately 1000-fold lower concentrations than lidocaine, prolongs the action of lidocaine in peripheral nerve block.
Article
The admixture of clonidine or epinephrine to lidocaine for brachial plexus block was studied with regard to duration of block, postoperative analgesia, and plasma concentrations of lidocaine. Thirty-three patients of ASA physical status I and II received an admixture of either clonidine (150 micrograms; n = 15) or epinephrine (200 micrograms; n = 18) to 40 mL of 1% lidocaine in a randomized, double-blind fashion. Bone surgery predominated in those patients receiving clonidine and soft-tissue surgery in those receiving epinephrine (P less than 0.05). Onset and duration of block were not different between the groups. With the admixture of clonidine, fewer patients were completely pain free for greater than 12 h (13.3%) and pain scores (visual analogue scale 0-10) were higher 6 h after the block (median 4; range 0-6) than with epinephrine (61.1%; median 2; range 0-7, respectively; P less than 0.05). In patients who had received clonidine, peak plasma concentrations of lidocaine were higher (10.29 +/- 2.96 mumol/L) and occurred earlier (23.7 +/- 9.3 min; mean +/- SD) than in those treated with epinephrine (6.9 +/- 1.71 mumol/L; 72.5 +/- 56.2 min; P less than 0.05). This indicates the absence of a local vasoconstrictor effect of clonidine and implies a reduced margin of safety with regard to local anesthetic toxicity. Although clonidine does not offer advantages compared with epinephrine, it may be a useful adjunct to local anesthetics in those patients in whom the administration of epinephrine is contraindicated.
Article
We have examined the effectiveness of extradural clonidine infusions for postoperative analgesia and the effect of clonidine on extradural morphine. In a double-blind, controlled study, patients, undergoing total hip replacement were allocated randomly to receive one of two doses of extradural clonidine (25 µg h−1 or 50µg h−1), low dose extradural morphine or a combination of morphine and clonidine. Pain scores in the morphine group were significantly greater than in the clonidine groups (P < 0.01) and the combination group (P < 0.05) during the first 1 h after surgery. The requirements for systemic analgesia were least in the combination and larger dose clonidine group, and the duration of effect of the initial bolus dose was significantly longer compared with the morphine and low dose clonidine groups (P < 0.05). Arterial pressure was reduced in the clonidine groups, although the incidence of clinical hypotension was low. There were no significant differences between the groups in emetic symptoms or urinary retention.
Article
Epidurally administered clonidine represents a new approach to postcesarean section pain therapy, yet the appropriate bolus dose and infusion to provide effective pain relief have not been defined. In addition, whether 2-chloroprocaine, a commonly used local anesthetic for intraoperative anesthesia, interferes with clonidine's analgesia, as it does with that of opioids, has not been examined. In this study, using a randomized, blinded design, 63 women received either bupivacaine or 2-chloroprocaine for epidural anesthesia for cesarean section and then received, upon request for analgesia in the recovery room, epidural clonidine 400 micrograms or 800 micrograms bolus, each followed by a 24-h infusion of 40 micrograms/h, or an equivalent volume bolus and infusion of saline. In the bupivacaine group, both clonidine doses produced equivalent analgesia, as determined by pain scores and time to first supplemental intravenous morphine request, and sustained analgesia was produced by clonidine infusion, as measured by need for supplemental morphine. In contrast, 2-chloroprocaine diminished analgesia from 800 micrograms by 21% and abolished analgesia from 400 micrograms clonidine. After 2-chloroprocaine, sustained analgesia from continuous clonidine infusion was present only in the group who had received 800 micrograms clonidine. Clonidine did not alter resolution of residual local anesthetic sensory blockade, as measured by 2- or 4-segment regression following either local anesthetic, but did prolong duration of motor blockade in women receiving bupivacaine. Clonidine produced small decreases in heart rate and blood pressure. One patient received iv fluids for hypotension; one had asymptomatic bradycardia resolving without therapy; and one had mild hypoxemia with snoring during clonidine-induced sedation, responding to supplemental oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The effects of clonidine and epinephrine, administered into the brachial plexus sheath, were evaluated in 60 patients who underwent surgery of the upper limb. All patients received 40 to 50 ml of 0.25% bupivacaine, injected into the brachial plexus sheath, using the supraclavicular technique. The patients were randomly allocated to two groups so that 30 patients received 150 micrograms clonidine hydrochloride (Group I), and 30 received 200 micrograms epinephrine (Group II). The quality and the duration of analgesia were assessed as well as the possible side-effects. The block produced with the addition of clonidine was longer (994.2 +/- 34.2 vs 728.3 +/- 35.8 min) and superior to that with epinephrine (P less than 0.001). No major side-effects were recorded. We conclude that the injection of clonidine into the brachial plexus sheath is an attractive alternative to epinephrine to prolong the duration of analgesia following upper limb surgery under conduction anaesthesia.
Article
Epidural clonidine produces postoperative analgesia in patients and potentiates opioid analgesia in animals. The aim of the current study was to assess the effect of epidural clonidine on the plasma concentrations and analgesic effect of fentanyl after epidural administration. Twenty ASA physical status 2 or 3 patients recovering from abdominal surgery were allocated randomly to receive either epidural fentanyl (100 micrograms in 10 ml isotonic saline; EF group) or epidural fentanyl (same dose) plus epidural clonidine (150 micrograms; EF + C group) in isotonic saline solution. Analgesia was assessed over a period of 12 h after epidural injection. Venous samples were obtained until 360 min after epidural injection for radioimmunoassay determination of plasma fentanyl concentration. Onset of analgesia was similar in the two groups of patients (13 +/- 6 and 13 +/- 3 min, respectively, after injection), but duration was more than doubled in the patients receiving clonidine (543 +/- 183 vs. 250 +/- 64 min). Peak plasma fentanyl concentrations (Fmax) and the time to reach Cmax (Tmax) were comparable in the two groups (0.29 +/- 0.15 ng.ml-1 at 16.2 +/- 14.8 min in the EF group and 0.27 +/- 0.11 ng.ml-1 at 8.3 +/- 5.5 min in the EF + C group), as were plasma concentrations at each definite time of measurement. Drowsiness and hypotension were noticed in the EF + C group. Thus, epidural clonidine appears to prolong epidural fentanyl analgesia without affecting its plasma concentration.
Article
Clonidine, an alpha 2 adrenoreceptor agonist, has nonopiate antinociceptive properties, which might be an alternative for postoperative analgesia free of opioid-induced side effects. To document the analgesic properties of intravenous clonidine during the postoperative period, 50 ASA physical status 1 patients, immediately after spinal fusion, were randomly assigned to two groups, blindly administered either clonidine (5 micrograms/kg infused the 1st h and then 0.3 microgram-1.kg-1.h-1 during 11 h) or a placebo. A visual analog scale graded from 0 (no pain) to 100 mm was used to assess pain before clonidine or placebo administration (T0), at the end of the loading dose (T1) and then every 2 h (T3, T5, T7, T9, and T11). Morphine (0.1 mg/kg) was administered intramuscularly after each pain measurement if the score was greater than 50 mm. No morphine was given at T0. Hemodynamics, blood gases and plasma clonidine concentrations were measured each time the pain score was measured. The pain score decreased from 42 +/- 5 to 26 +/- 3 mm (mean +/- standard error) in the clonidine group whereas it was unchanged in the placebo group despite a greater morphine requirement (dose for each patient: 3.8 +/- 1 vs. 10.8 +/- 1.2 mg). Clonidine delayed the onset of pain and the first request for morphine injection. Mean arterial pressure decreased to 74 +/- 2 mmHg in the clonidine group (-26 +/- 2 vs. -15 +/- 2% in the placebo group at T11) despite a significant increase in the cumulative fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
This study was undertaken to evaluate the analgesic effect of the combination of epidural morphine and clonidine versus epidural morphine alone in patients with postoperative pain. A randomized double-blind design was used, and 91 patients scheduled for post-operative pain relief by epidural morphine were studied. Patients received either a continuous epidural infusion of morphine and clonidine (group 1; n = 45) or morphine alone (group 2; n = 46) over the 72 h after major abdominal surgery. In the first 24 h, the dose of morphine was 6 mg per 24 h; during the second 24 h, it was decreased to 4 mg per 24 h; and in the final 24 h, it was decreased to 2 mg per 24 h in both groups. Group 1 patients received clonidine (450 micrograms) during each 24-h period. Additional epidural bolus injections of 2 mg morphine and intravenous meperidine were given on demand. The pain score, blood pressure, heart rate, respiratory rate, and relative forced vital capacity were measured at fixed times during the first 72 h after operation. Total consumption of analgesics and side effects were recorded. Although the total consumption of analgesics was significantly higher in group 2 (P less than 0.05), pain scores were lower in group 1 than group 2 during the entire observation period (P less than 0.05). Epidural clonidine produced a significant decrease (P less than 0.05) in heart rate and blood pressure, whereas the respiratory rate was not affected. Due to the better pain relief in group 1, the forced vital capacity was increased (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The authors studied in a double-blind placebo-controlled study the effects of oral preoperative administration of 5 micrograms/kg clonidine upon the alfentanil and droperidol requirements, hemodynamic lability, distribution of the values of heart rate and blood pressure, and plasma noradrenaline levels, in two groups of ten normotensive patients undergoing infrarenal aortic surgery. The amounts of alfentanil supplementing a standardized continuous infusion, injected to maintain hemodynamic stability, were statistically identical between the groups (P = 0.23). The amount of droperidol, however, was significantly less (P = 0.004) in the group of patients that received clonidine. The norepinephrine plasma concentrations, during the entire procedure, were lower (P = 0.001) in the clonidine group. The variability of the heart rate, systolic (SBP) and diastolic (DBP) blood pressure recorded every 5 s, and assessed by the calculation of the coefficients of variation for each patient, showed no difference between the clonidine and the placebo group. However, when the values recorded were compared to the preoperative baseline values, and divided into three categories (baseline +/- 20%--greater than 20% decrease vs. baseline--greater than 20% increase vs. baseline), the clonidine group showed a higher frequency of low heart rate and fewer episodes of tachycardia. The frequency of SBP hypertension was lower and of SBP hypotension higher in the clonidine group. After induction of anesthesia, but before surgery, there were more episodes of DBP hypotension in the clonidine group, but during dissection and vascular sutures the placebo group experienced more episodes of DBP hypotension, owing probably to the greater amount of droperidol injected. The authors conclude that the preoperative administration of clonidine decreased the need to supplement anesthetic, and modifies the profile of distribution of heart rate and blood pressure.
Article
The effect of clonidine, an alpha 2 agonist, on sensory and motor blockade during spinal anesthesia was studied in 44 ASA physical status I II patients scheduled for orthopedic surgery. The patients were randomly allocated into three groups given 15 mg of 0.5% hyperbaric tetracaine (HT), within group I (N = 14) 1 ml isotonic saline, in group II (N = 15) 0.5 ml saline solution and 0.5 ml clonidine (75 micrograms), and in group III (N = 15) 1 ml clonidine (150 micrograms). Sensory blockade (SB) was evaluated by pinprick and motor blockade (MB) according to Bromage's scale. The level of SB was comparable in the three groups but the duration was different. The 75 micrograms clonidine was associated with 25% prolongation of SB at L2 and 29% prolongation of grade 3 MB Clonidine 150 micrograms prolonged the time of SB at L2 by 72% and grade 3 MB by 96%. Colloid infusion and the decrease in diastolic blood pressure were significantly greater in the clonidine 150 micrograms group compared to group I. A dose related prolongation of spinal anesthesia is demonstrated with clonidine.
Article
Epidurally administered clonidine has been reported to produce postoperative analgesia. To assess the efficacy, safety, and appropriate dose of epidural clonidine for postoperative analgesia, clonidine (range, 100-900 micrograms in 100-micrograms increments) was injected in 22 patients following abdominal surgery or total knee arthroplasty (TKA). Clonidine produced analgesia, as measured by change in verbal pain scores and supplemental iv morphine usage. The largest doses examined (700-900 micrograms) produced complete pain relief for 5.0 +/- 0.8 h (mean +/- SEM; range 2-11 h), without other sensory or motor blockade. Clonidine also produced dose dependent decreases in blood pressure, being less following small (100-300 micrograms) and large (700-900 micrograms) doses than following intermediate (400-600 micrograms) doses. Six patients required iv ephedrine for treatment of blood pressure decrease of greater than 30%. Clonidine decreased heart rate 10-30% and produced transient sedation. Oxyhemoglobin saturation, serum glucose, and arterial blood gas tensions were not altered by clonidine, whereas there was a small (28%) dose-independent decrease in serum cortisol following clonidine injection. Clonidine was absorbed in a dose-dependent manner into the systemic circulation, with plasma concentrations 0.1-3.3 ng/ml 1 h following injection. These results suggest that hemodynamic depression and short-lasting analgesia may limit the usefulness of bolus epidural clonidine analgesia in the postoperative setting.
Article
Clonidine has been reported to produce analgesia in humans in different painful conditions. The aim of the present study was to investigate if epidural clonidine produced a clinically important analgesia to severe postoperative pain. Using a controlled, randomized double-blind design, one group of patients received a single dose of epidural clonidine 3 micrograms/kg (n = 10) and a control group epidural 0.9% saline (n = 10), when reporting postoperative pain after thoracotomy performed under standardized anaesthesia. To quantify the effects of the given epidural drugs, the need for supplementary, intravenous pethidine analgesia was recorded. The patients had access to the supplementary analgesic by means of a patient-controlled analgesic-delivery device. The two groups were similar regarding anthropometric and clinical data. Epidural clonidine 3 micrograms/kg did not affect the need for supplementary intravenous pethidine analgesia, as compared to the control group at any time during the first 12 h postoperatively. The side-effects of epidural clonidine were tolerable, and no treatment for arterial hypotension was required. No early or delayed respiratory depression occurred. In conclusion, clonidine 3 micrograms/kg epidurally seems to lack clinically important analgesic effects on severe postoperative pain, at least following thoracotomy.
Article
Clonidine analgesia was tested on the hyperalgesia induced by intraplantar injection of prostaglandin E2 or carrageenin. The antinociceptive effect of clonidine was dose-dependent and was abolished by local administration of the selective alpha 2-adrenoceptor blocker, yohimbine or of the opioid antagonists naloxone or quaternary nalorphine. St-91, a clonidine analog which does not cross the blood-brain barrier also promoted significant antinociception. Repeated administration of drugs possessing a central mechanism of analgesic action leads to the development of tolerance in this test. Significant analgesic tolerance was observed following repeated (5 days) morphine (8 mg/kg) or high doses of clonidine (0.5 mg/kg). In contrast, no tolerance was detected to the analgesic effect of low doses of clonidine (0.15 mg/kg) or of St-91 (0.5 mg/kg). These results suggest that, in addition to its central analgesic action, clonidine can induce peripheral antinociception by an alpha 2-adrenoceptor-mediated local release of enkephalin-like substances.