Philip W. H. Peng

Failed back surgery syndrome.

BACKGROUNDnFailed back surgery syndrome (FBSS) is a chronic pain condition that has considerable impact on the patient and health care system. Despite advances in surgical technology, the rates of failed back surgery have not declined. The factors contributing to the development of this entity may occur in the preoperative, intraoperative, and postoperative periods. Due to the severe pain and disability this syndrome may cause, more radical treatments have been utilized. Recent trials have been published that evaluate the efficacy and cost-effectiveness of therapeutic modalities such as spinal cord stimulation for the management of patients with failed back surgery.nnnREVIEW SUMMARYnThis article will describe the epidemiology and etiology of FBSS. The importance of prevention will be emphasized. In those patients with established FBSS, a guide to interdisciplinary evaluation and management will be outlined. Special attention will focus on recent trials that have studied the efficacy of more invasive procedures such as spinal cord stimulation. Finally, a suggested management pathway is presented.nnnCONCLUSIONnFBSS is a challenging clinical entity with significant impact on the individual and society. To better prevent and manage this condition, knowledge of the factors contributing to its development is necessary. While research on FBSS has increased in recent years, perhaps the best strategy to reduce incidence and morbidity is to focus on prevention. Patients diagnosed with FBSS should be managed in an interdisciplinary environment. More radical treatments for FBSS have now been extensively studied providing clinicians with much needed evidence on their efficacy. Incorporating these results into our current knowledge provides a basis on which to construct an evidence-based guide on how best to manage patients who suffer from FBSS.

what Is the Relationship Between Paresthesia and Nerve Stimulation for Axillary Brachial Plexus Block

Background and Objectives To quantify the motor threshold current of a needle following elicitation of paresthesia during axillary brachial plexus block (ABPB). Methods This is a prospective, observational study of ABPB in 72 patients. Having elicited paresthesia, the minimum current required to produce a motor response was noted. The development and success of the block were subsequently followed. Results Nineteen blocks were excluded (18 because of arterial puncture and 1 blocked needle). Of the remaining 53 blocks, 41 (77%) produced a motor response at 0.5 mA or less. The median current was 0.17 mA (range, 0.03 to 3.3 mA). The site of initial paresthesia and subsequent motor response were related in 43 (81%) of cases. Conclusions A needle position causing paresthesia produced a motor response at 0.5 mA or less in 77% of cases studied. This current may, therefore, be a reasonable threshold to aim for when performing an ABPB.

Use of Gabapentin for Perioperative Pain Control – a Meta-Analysis

BACKGROUNDnGabapentin, an anticonvulsant, has recently been suggested as an effective postoperative analgesic agent. The objective of the present study was to examine the analgesic effectiveness, opioid-sparing effects and side effects associated with the use of gabapentin in a perioperative setting.nnnMETHODSnFollowing the Quality of Reporting of Meta-analyses recommendations, nine electronic databases until February 2006 were searched, without language restriction, for randomized controlled trials comparing gabapentin with control for postoperative pain control. Outcome measures, namely, 24 h cumulative opioid consumption, visual analogue scale pain scores and adverse effects, were expressed as odds ratios, ratio of means or weighted mean differences (as appropriate), which were aggregated under the fixed or random effects models.nnnRESULTSnGabapentin caused a 35% reduction in total opioid consumption over the first 24 h following surgery (ratio of means 0.65, 95% CI 0.59 to 0.72), a significant reduction in postoperative pain at rest (in the first 24 h) and with movement (at 2 h, 4 h and 12 h), regardless of whether treatment effects were expressed as ratios of means or weighted mean differences, and a reduction of vomiting (relative risk [RR] 0.73, 95% CI 0.56 to 0.95) and pruritus (RR 0.30, 95% CI 0.13 to 0.70). It was associated with a significant increase in dizziness (RR 1.40, 95% CI 1.06 to 1.84) and an increase in sedation of borderline significance (RR 1.65, 95% CI 1.00 to 2.74).nnnCONCLUSIONnGabapentin improves the analgesic efficacy of opioids both at rest and with movement, reduces analgesic consumption and opioid-related adverse effects, but is associated with an increased incidence of sedation and dizziness.

A systematic review of adjuncts for intravenous regional anesthesia for surgical procedures

PurposeTo review the use of adjuncts to intravenous regional anesthesia (IVRA) for surgical procedures in terms of their intraoperative effects (efficacy of block and tourniquet pain) and postoperative analgesia.SourceA systematic search (Medline, Embase, reference lists) for randomized, controlled and double-blinded studies using adjuncts to IVRA for surgical procedures was conducted. Data were collected on intraoperative effects (onset/offset and quality of block and tourniquet pain), postoperative effects (pain intensity and analgesic consumption) and side effects recorded. Statistical significance as indicated in the original report and likely clinical relevance were taken into account to arrive at a judgment of overall benefit.Principal findingsTwenty-nine studies met all inclusion criteria. Data on 1,217 study subjects are included. Adjuncts used were opioids (fentanyl, meperidine, morphine, sufentanil), tramadol, nonsteroidal anti-inflammatory drugs (NSAIDs; ketorolac, tenoxicam, acetyl-salicylate), clonidine, muscle relaxants (atracurium, pancuronium, mivacurium), alkalinization with sodium bicarbonate, potassium and temperature. There is good evidence to recommend NSAIDs in general and ketorolac in particular, for improving postoperative analgesia. Clonidine 1 μg·kg−1 also appears to improve postoperative analgesia and prolong tourniquet tolerance. Opioids are poor by this route; only meperidine 30 mg or more has substantial postoperative benefit but at the expense of postdeflation nausea, vomiting and dizziness. Muscle relaxants improve intraoperative motor block and aid fracture reduction.ConclusionUsing NSAIDs or clonidine as adjuncts to IVRA improves postoperative analgesia and muscle relaxant improves motor block.RésuméObjectifPasser en revue l’usage des traitements d’appoint à l’anesthésie régionale intraveineuse (ARIV) pour les interventions chirurgicales, en termes des effets peropératoires (efficacité du bloc et douleur du garrot et de l’analgésie postopératoire.SourceUne recherche systématique (bases de données Medline, Embase, listes de références) des études randomisées, contrôlées et à double insu utilisant les traitements d’appoint à l’ARIV pendant les interventions chirurgicales a été réalisée. Les données concernant les effets peropératoires ont été recueillies (début/fin et qualité du bloc et douleur de garrot) ainsi que les effets postopératoires (intensité de la douleur et consommation analgésique) et les effets secondaires. La signification statistique, tel qu’indiqué dans l’article original, et la pertinence clinique possible ont été retenues afin d’en arriver à un jugement sur les bienfaits généraux.Constatations principalesVingt-neuf études répondaient à tous les critères d’inclusion. Les données sur 1 217 sujets d’étude ont été compilées. Les traitements d’appoint étaient des opioïdes (fentanyl, mépéridine, morphine, sufentanil), le tramadol, les anti-inflammatoires non stéroïdiens (AINS; kétorolac, ténoxicam, acétylsalicylique), la clonidine, les myorelaxants (atracurium, pancuronium, mivacurium), l’alcalinisation avec le bicarbonate de sodium, le potassium et la température. Il existe de bonnes indications pour l’utilisation des AINS en général et du kétorolac en particulier concernant l’analgésie postopératoire. L’administration de 1μg·kg− 1 de clonidine semble améliorer l’analgésie postopératoire et la tolérance prolongée du garrot. Les opioïdes font piètre figure dans ces circonstances; seule une dose de 30 mg ou plus de mépéridine présente des bienfaits postopératoires substantiels, mais aux dépens de nausées, de vomissements et d’étourdissement au relâchement du garrot. Les myorelaxants améliorent le bloc moteur peropératoire et favorisent la réduction de fracture.ConclusionL’utilisation de AINS ou de clonidine comme traitement d’appoint de l’ARIV améliore l’analgésie postopératoire tandis que les myorelaxants améliore le bloc moteur.

The Canadian STOP-PAIN project - Part 1: Who are the patients on the waitlists of multidisciplinary pain treatment facilities?

PurposeThe Canadian STOP-PAIN Project assessed the human and economic burden of chronic pain in individuals on waitlists of Multidisciplinary Pain Treatment Facilities (MPTF). This article presents the patients’ bio-psycho-social profile.MethodsA sample of 728 patients was recruited from waitlists of eight university-affiliated MPTFs across Canada. Subjects completed validated questionnaires to: 1) assess the characteristics and impact of their pain; and 2) evaluate their emotional functioning and quality of life (QoL). Follow-up questionnaires were completed by a subgroup of 271 patients three months later.ResultsClose to 2/3 of the participants reported severe pain (≥xa07/10) that interfered substantially with various aspects of their daily living and QoL. Severe or extremely severe levels of depression were common (50.0%) along with suicidal ideation (34.6%). Patients agedxa0>xa060xa0yr were twice as likely to experience severe pain (≥xa07/10) as their younger counterparts (Pxa0=xa00.002). Patients with frequent sleep problems were more at risk of reporting severe pain (Pxa0≤xa00.003). Intense pain was also associated with a greater tendency to catastrophize (Pxa0<xa00.0001) severe depressive symptoms (Pxa0=xa00.003) and higher anger levels (Pxa0=xa00.016). Small but statistically significant changes in pain intensity and emotional distress were observed over a three-month wait time (all Pxa0<xa00.05).ConclusionThis study highlights the severe impairment that patients experience waiting for treatment in MPTFs. Knowing that current facilities cannot meet the clinical demand, it is clear that effective prevention/treatment strategies are needed earlier in primary and secondary care settings to minimize suffering and chronicity.RésuméObjectifLe projet canadien STOP-PAIN a évalué le fardeau humain et économique que représentait la douleur chronique des personnes se trouvant sur les listes d’attente des établissements pluridisciplinaires de traitement de la douleur (MPTF – Multidisciplinary Pain Treatment Facilities). Cet article présente le profil bio-psycho-social de ces patients.MéthodeUn échantillon de 728 patients a été recruté à partir des listes d’attente de huit MPTF affiliés à des universités partout au Canada. Les participants ont rempli des questionnaires validés afin dexa0: 1) évaluer les caractéristiques et l’impact de leur douleur; et 2) évaluer leur fonctionnement émotionnel et leur qualité de vie (QdV). Des questionnaires de suivi ont été remplis trois mois plus tard par un sous-groupe de 271 patients.RésultatsPrès de 2/3 des participants ont fait état d’une douleur grave (≥xa07/10) qui entravait considérablement différents aspects de leur vie quotidienne et de leur QdV. Des niveaux graves ou extrêmement graves de dépression étaient fréquents (50,0xa0%), tout comme les idées suicidaires (34,6xa0%). Les patients âgés dexa0>xa060 ans couraient un risque deux fois plus élevé de ressentir des douleurs graves (≥xa07/10) que les participants plus jeunes (Pxa0=xa00,002). Les patients ayant souvent des problèmes de sommeil couraient un risque plus élevé de faire état de douleur grave (Pxa0≤xa00,003). Une douleur intense était également associée à une tendance plus prononcée à la dramatisation (Pxa0<xa00,0001), à des symptômes de dépression grave (Pxa0=xa00,003) et à des niveaux plus élevés de colère (Pxa0=xa00,016). Des changements petits mais significatifs au niveau de l’intensité de la douleur et de la détresse émotionnelle ont été observés sur une période d’attente de trois mois (tous Pxa0<xa00,05).ConclusionCette étude met en évidence le handicap grave que les patients ressentent pendant qu’ils attendent d’être traités dans un MPTF. Sachant que les établissements actuels ne peuvent répondre à la demande clinique, il est clair que des stratégies de prévention et de traitement efficaces sont nécessaires plus tôt dans les cadres de soins primaires et secondaires afin de minimiser la souffrance et la chronicité.

Review article: Perioperative pain management of patients on methadone therapy

PurposeMethadone, an opioid traditionally associated with the management of opioid addictive disorders, has been prescribed increasingly as an analgesic for the management of various chronic pain conditions. Despite the increasing popularity of methadone, most anesthesiologists are not familiar with its complex pharmacology. The purpose of this article is to review the pharmacology of methadone and to suggest a management algorithm for the perioperative care of methadone patients.SourceA Medline search was performed to obtain the published literature on the pharmacology of methadone and its use perioperatively.Principal findingsThe complexity of methadone’s pharmacology is characterized by a high inter-individual variability, a potential for interaction with other medications, and a long elimination half-life. The postoperative management of methadone patients may be difficult as they are often ‘opioid-tolerant’ but may be ‘pain-intolerant’. For those patients who are taking part in methadone-maintenance programs, there is a potential for the problematic use of opioids or other substances. The management plan for patients taking methadone may differ depending on the type of surgery and the associated perioperative differences in fasting status and gastrointestinal function. In consideration of all the factors listed above, a management algorithm is outlined for the perioperative care of methadone patients.ConclusionMethadone is an opioid with complex properties, and a patient that is taking methadone can represent a unique challenge to the anesthesiologist. A good understanding of the pharmacology of methadone and of the type of patients on this medication will help to improve their perioperative care.RésuméObjectifLa méthadone, opiacé habituellement associé au traitement des dépendances aux opiacés, est prescrite de plus en plus comme analgésique pour diverses douleurs chroniques. Malgré sa popularité croissante, la plupart des anesthésiologistes n’en connaissent pas la pharmacologie complexe. Nous avons revu la pharmacologie et recommander un algorithme de traitement périopératoire pour les patients traités avec la méthadone.SourceUne recherche dans Medline a été réalisée pour obtenir les publications sur la pharmacologie de la méthadone et son usage périopératoire.Constatations principalesLa complexité de la pharmacologie de la méthadone est caractérisée par une grande variabilité inter-individuelle, un potentiel d’interaction avec d’autres médicaments et une longue demi-vie d’élimination. Le traitement postopératoire des patients sous méthadone peut être difficile, car ils présentent souvent une «tolérance aux opiacés», mais ils peuvent être «intolérants à la douleur». Dans les cas de traitements d’entretien à la méthadone, il y a des problèmes possibles avec l’usage d’opiacés ou d’autres substances. Le plan de traitement des patients sous méthadone peut différer selon le type de chirurgie et les différences périopératoires associées de l’état de jeûne et de la fonction gastro-intestinale. En considérant tous ces facteurs, un algorithme de traitement est tracé pour les soins périopératoires des patients sous méthadone.ConclusionLa méthadone est un opiacé aux propriétés complexes et l’anesthésie d’un patient sous méthadone peut représenter un grand défi. Une bonne connaissance de sa pharmacologie et du type de patients qui en consomment aidera à améliorer les soins périopératoires.

Feasibility of Real-Time Ultrasound for Pudendal Nerve Block in Patients with Chronic Perineal Pain

Background and Objectives: Compared with conventional fluoroscopic‐guided pudendal nerve block, ultrasonography has potential advantages for visualizing anatomical landmarks such as the internal pudendal artery and nerve, the sacrospinous and sacrotuberous ligaments, and local anesthetic spread. We examined the clinical utility of performing pudendal nerve block under real‐time ultrasound guidance. Methods: Seventeen patients were studied. With the patient lying prone, a 2 to 5 MHz curved array ultrasound probe was placed at the level of the ischial spine to capture the transverse view of the ischial spine, the sacrospinous and sacrotuberous ligaments (SSL and STL), the internal pudendal artery (confirmed with color Doppler), and the pudendal nerve. A 22‐gauge needle was advanced under real‐time ultrasound guidance to reach the pudendal nerve in the plane between the STL and SSL. Following confirmation of spread of dextrose 5% solution in the interligamentous plane, a mixture of 5 mL 0.25% bupivacaine with 1:200,000 epinephrine and 40 mg Depo‐Medrol (Pharmacia & Upjohn, Kalamazoo, MI) was injected. Assessment included the ease of identification of anatomical structures and local anesthetic spread with ultrasound, and the degree of sensory block in the perineum. Results: The ischial spine, SSL, STL, internal pudendal artery, and pudendal nerve were easily identifiable with ultrasound in the majority of patients. Local anesthetic spread was seen as a hypoechoic collection around the nerve and expanding between the STL and SSL. All patients developed perineal sensory block following the procedure. Conclusions: Pudendal nerve block at the ischial spine level can be reliably performed under real‐time ultrasound guidance.

Analgesic effects of low-dose ropivacaine for interscalene brachial plexus block for outpatient shoulder surgery—A dose-finding study

Background and Objectives Interscalene brachial plexus block (ISB) with low-dose bupivacaine provides effective postoperative shoulder analgesia in outpatients. The analgesic effect of low-dose ropivacaine for ISB is unknown. Methods In this double-blind study, 66 outpatients scheduled to undergo arthroscopic shoulder surgery were randomly assigned to receive an ISB with 10 mL of 0.125%, 0.25%, or 0.5% ropivacaine before surgery. Postoperative verbal pain rating score, analgesic consumption, and the extent of motor and sensory block was assessed for 120 minutes after surgery. Results The degree of shoulder analgesia was dose dependent. Postoperative pain scores were lowest with 0.5% ropivacaine, and analgesic was not required in the hospital in 70% of the patients who received 0.25% and 0.5% ropivacaine, compared to 30% with 0.125% ropivacaine (P < .03). In the patients who required no analgesic in the hospital, the time to first oral analgesic at home was approximately 10 hours irrespective of ropivacaine concentration. Motor and sensory block distal to the elbow was detected in 25% of the patients in the 0.5% group but none in the 0.125% group. Conclusions Interscalene brachial plexus block with low-dose ropivacaine, 10 mL of 0.25% and 0.5%, provides effective long-lasting shoulder analgesia in a majority of patients after arthroscopic surgery.

The Canadian STOP-PAIN project – Part 2: What is the cost of pain for patients on waitlists of multidisciplinary pain treatment facilities?

PurposeThe Canadian STOP-PAIN Project was designed to document the human and economic burden of chronic pain in individuals on waitlists of Multidisciplinary Pain Treatment Facilities (MPTF). This paper describes the societal costs of their pain.MethodsA subgroup of 370 patients was selected randomly from The Canadian STOP-PAIN Project. Participants completed a self-administered costing tool (the Ambulatory and Home Care Record) on a daily basis for three months. They provided information about publicly financed resources, such as health care professional consultations and diagnostic tests as well as privately financed costs, including out-of-pocket expenditures and time devoted to seeking, receiving, and providing care. To determine the cost of care, resources were valued using various costing methods, and multivariate linear regression was used to predict total cost.ResultsOverall, the median monthly cost of care was

Ultrasound-guided suprascapular nerve block: a correlation with fluoroscopic and cadaveric findings

1,462 (CDN) per study participant. Ninety-five percent of the total expenditures were privately financed. The final regression model consisted of the following determinants: educational level, employment status, province, pain duration, depression, and health-related quality of life. This model accounted for 35% of the variance in total expenditure (Pxa0<xa00.001).ConclusionThe economic burden of chronic pain is substantial in patients on waitlists of MPTFs. Consequently, it is essential to consider this burden when making decisions regarding resource allocation and waitlist assignment for a MPTF. Resource allocation decision-making should include the economic implications of having patients wait for an assessment and for care.RésuméObjectifLe projet canadien STOP-PAIN a été élaboré afin de documenter le fardeau humain et économique que représentait la douleur chronique pour les personnes se trouvant sur les listes d’attente des établissements pluridisciplinaires de traitement de la douleur (MPTF – Multidisciplinary Pain Treatment Facilities). Cet article décrit les coûts sociétaux de leur douleur.MéthodeUn sous-groupe de 370 patients a été aléatoirement choisi parmi les participants au projet canadien STOP-PAIN. Les participants ont rempli quotidiennement un outil auto-administré de calcul des coûts (le fichier de soins ambulatoires et à domicile - Ambulatory and Home Care Record) pendant trois mois. Ils ont fourni des renseignements concernant les ressources financées par le secteur public, comme par exemple les consultations auprès de professionnels de la santé et les tests diagnostiques, ainsi que les coûts privés, notamment les sorties effectives d’argent et le temps consacré à chercher, recevoir et fournir des soins. Afin de déterminer le coût des soins, les ressources ont été estimées à l’aide de plusieurs méthodes de calcul des coûts, et une analyse par régression linéaire multivariée a été appliquée afin d’estimer le coût total.RésultatsGlobalement, le coût mensuel moyen des soins était de 1462xa0