The role of continuous peripheral nerve blocks

Does intravenous patient-controlled analgesia or continuous block prevent rebound pain following infraclavicular brachial plexus block after distal radius fracture fixation? A prospective randomized controlled trial

BACKGROUND

The purpose of this study was to investigate the role of opioid-based intravenous patient-controlled analgesia (IV PCA) or continuous brachial plexus block (BPB) in controlling rebound pain after distal radius fracture (DRF) fixation under BPB as well as total opioid consumption.

METHODS

A total of 66 patients undergoing surgical treatment for a displaced DRF with volar plate fixation were randomized to receive a single infraclavicular BPB (BPB only group) (n = 22), a single infraclavicular BPB with IV PCA (IV PCA group) (n = 22), or a single infraclavicular BPB with continuous infraclavicular BPB (continuous block group) (n = 22). The visual analog scale (VAS) for pain and the amount of pain medication were recorded at 4, 6, 9, 12, 24, and 48 h and two weeks postoperatively.

RESULTS

At postoperative 9 h, the pain VAS score was significantly higher in the BPB only group (median: 2; Q1, Q3 [1, 3]) than in the IV PCA (0 [0, 1.8], P = 0.006) and continuous block groups (0 [0, 0.5], P = 0.009). At postoperative 12 h, the pain VAS score was significantly higher in the BPB only group (3 [3, 4]) than in the continuous block group (0.5 [0, 3], P = 0.004). The total opioid equivalent consumption (OEC) was significantly higher in the IV PCA group (350.3 [282.1, 461.3]) than in the BPB only group (37.5 [22.5, 75], P < 0.001) and continuous block group (30 [15, 75], P < 0.001); however, OEC was not significantly different between the BPB only group and the continuous block group (P = 0.595).

CONCLUSIONS

Although continuous infraclavicular BPB did not reduce total opioid consumption compared to BPB only, this method is effective for controlling rebound pain at postoperative 9 and 12 h following DRF fixation under BPB.

The influence of intervertebral disc overloading on nociceptor calcium flickering

Introduction

Mechanical overloading can trigger a degenerative-like cascade in an organ culture of intervertebral disc (IVD). Whether the overloaded IVD can influence the activation of nociceptors (i.e., the damage sensing neurons) remains unknown. The study aims to investigate the influence of overloaded IVD conditioned medium (CM) on the activation of nociceptors.

Methods

In the static loading regime, force-controlled loading of 0.2 MPa for 20 h/day representing "long-term sitting and standing" was compared with a displacement-controlled loading maintaining original IVD height. In the dynamic loading regime, high-frequency-intensity loading representing degenerative "wear and tear" was compared with a lower-frequency-intensity loading. CM of differently loaded IVDs were collected to stimulate the primary bovine dorsal root ganglion (DRG) cultures. Calcium imaging (Fluo-4) and calcitonin gene-related peptide (CGRP) immunofluorescent labeling were jointly used to record the calcium flickering in CGRP(+) nociceptors.

Results

Force-controlled loading led to a higher IVD cell death compared to displacement-controlled loading. Both static and dynamic overloading (force-controlled and high-frequency-intensity loadings) elevated the frequency of calcium flickering in the subsurface space of CGRP(+) nociceptors compared to their mild loading counterparts.

Conclusion

In the organ culture system, IVD overloading mediated an altered IVD-nociceptor communication suggesting a biological mechanism associated with discogenic pain.

Pain Management Considerations in Patients with Opioid Use Disorder Requiring Critical Care

The opioid epidemic has resulted in increased opioid-related critical care admissions, presenting challenges in acute pain management. Limited guidance exists in the management of critically ill patients with opioid use disorder (OUD). This narrative review provides the intensive care unit (ICU) clinician with guidance and treatment options, including non-opioid analgesia, for patients receiving medications for opioid use disorder (MOUD) and for patients actively misusing opioids. Verification and continuation of the patient's outpatient MOUD regimen, specifically buprenorphine and methadone formulations, assessment of pain and opioid withdrawal, and treatment of acute pain with non-opioid analgesia, nonpharmacologic strategies, and short-acting opioids as needed, are all essential to adequate management of acute pain in patients with OUD. A multidisciplinary approach to treatment and discharge planning in patients with OUD may be beneficial to engage patients with OUD early in their hospital stay to prevent withdrawal, stabilize their OUD, and to reduce the risk of unplanned discharge and other associated morbidity. This article is protected by copyright. All rights reserved.

Regional Anaesthetic Techniques and Their Implications During the COVID Pandemic

The current pandemic has highlighted the need to protect both patients and medical staff. The increased use of regional anaesthesia as a primary anaesthetic modality for operations and other invasive procedures has limited the number of aerosol-generating procedures performed during general anaesthesia. Its use is further characterized by decreases in postoperative pain and length of hospitalization. This article provides an overview of regional anaesthetic techniques (peripheral nerve locks, epidural and spinal anaesthesia) and their uses during the COVID pandemic.

Nanotechnology for Pain Management: Current and Future Therapeutic Interventions

Pain is one of the most common medical conditions and affects more Americans than diabetes, heart disease, and cancer combined. Current pain treatments mainly rely on opioid analgesics and remain unsatisfactory. The life-threatening side effects and addictive properties of opioids demand new therapeutic approaches. Nanomedicine may be able to address these challenges as it allows for sensitive and targeted treatments without some of the burdens associated with current clinical pain therapies. This review discusses the physiology of pain, the current landscape of pain treatment, novel targets for pain treatment, and recent and ongoing efforts to effectively treat pain using nanotechnology-based approaches. We highl ight advances in nanoparticle-based drug delivery to reduce side effects, gene therapy to tackle the source of pain, and nanomaterials-based scavenging to proactively mediate pain signaling.

Does the performance of lower limb peripheral nerve blocks differ among orthopedic sub-specialties? A single institution experience in 246 patients

OBJECTIVES

Continuous peripheral nerve blocks (cPNBs) have shown promising results in pain management after orthopaedic surgeries. However, they can be associated with some risks and limitations. The purpose of this study is to describe our experience with the cPNBs regarding efficacy and adverse events in patients undergoing orthopedic surgeries on the lower extremity in different subspecialties.

METHODS

This is a prospective cohort study on collected data from perineural catheters for pain management after orthopedic surgeries in lower limbs. Catheters were placed by experienced anesthesiologists using sterile technique. After an initial bolus dose of 10-20 mL ropivacaine 0.5% (weight adjusted), the catheters were secured and connected to disposable mechanical infusion pumps with ropivacaine 0.2% (basal infusion rate = 6 mL/h; weight adjusted (0.2 mL/kg/h)). After catheterization, the patients were examined daily, by specially educated acute pain service nurses. Pro re nata (PRN) or fixed boluses (10 mL bupivacaine 0.25%; weight adjusted) with an upper limit of 4 times/day, were administered if indicated. Patients' demographic data, physiological status, and pre-op intake of opioids and other analgesics were registered. The severity of post-operative pain was assessed with 'Numeric Rating Scale' (NRS) and 'Face, legs, Activity, Cry, Consolability' (FLACC) scale for adults and children, respectively. The need for additional opioids and possible complications were registered.

RESULTS

We included 547 catheters of 246 patients (Range 1-10 catheters per patient). Overall, 115 (21%) femoral, 162 (30%) saphenous, 66 (12%) sciatic, and 204 (37%) popliteal sciatic nerve catheter were used. 452 (83%) catheters were inserted by a primary procedure, 61(11%) catheters employed as a replacement, and 34 catheters (6.2%) used as a supplement. For guiding the catheterization, ultrasound was applied in 451 catheters (82%), nerve stimulator in 90 catheters (16%), and both methods in 6 catheters (1.1%). The median duration a catheter remained in place was 3 days (IQR = 2-5). The proportion of catheters with a duration of two days was 81, 79, 73, and 71% for femoral, sciatic, saphenous, and popliteal nerve, respectively. In different subspecialties, 91% of catheters in wound and amputations, 89% in pediatric surgery, 76% in trauma, 64% in foot and ankle surgery, and 59% in limb reconstructive surgery remained more than two days. During first 10 days after catheterization, the proportion of pain-free patients were 77-95% at rest and 63-88% during mobilization, 79-92% of the patients did not require increased opioid doses, and 50-67% did not require opioid PRN doses. In addition to 416 catheters (76%), which were removed as planned, the reason for catheter removal was leaving the hospital in 27 (4.9%), loss of efficacy in 69 (13%), dislodgement in 23 (4.2%), leakage in 8 (1.5%), and erythema in 4 catheters (0.73%). No major complication occurred.

CONCLUSIONS

After orthopaedic procedures, cPNBs can be considered as an efficient method for improving pain control and minimizing the use of additional opioids. However, the catheters sometimes might need to be replaced to achieve the desired efficacy.

Factors associated with low levels of patient satisfaction following peripheral nerve block

Peripheral nerve blocks can provide surgical anaesthesia as well as excellent postoperative analgesia. When questioned postoperatively, however, some patients report low levels of satisfaction with their nerve block experience. At our hospital, patients undergoing regional anaesthesia have their patient characteristics, block characteristics and postoperative feedback routinely recorded in a block registry. We analysed data from 979 consecutive patients undergoing peripheral nerve block for orthopaedic surgery to identify factors associated with low levels of patient satisfaction. The primary outcome was patient satisfaction with their peripheral nerve block (scale 1-5: 4-5 is 'satisfied', 1-3 is 'not satisfied'). Eighty-nine percent (871/979) of patients reported being 'satisfied' with their block. Factors negatively associated with patient satisfaction were rebound pain (adjusted odds ratio (aOR) 0.19, 95% confidence interval (CI) 0.04 to 0.85 for moderate rebound pain; aOR 0.11, 95% CI 0.03 to 0.48 for severe rebound pain), discomfort during the block (aOR 0.37, 95% CI 0.16 to 0.82 for moderate discomfort; aOR 0.19, 95% CI 0.05 to 0.76 for severe discomfort) and pain in the post-anaesthesia care unit (aOR 0.30, 95% CI 0.17 to 0.55 for pain ≥8/10). Only 24% (26/108) of patients who reported being 'not satisfied' stated that they would be unwilling to undergo a hypothetical future nerve block. Rebound pain of at least moderate intensity, procedural discomfort of at least moderate intensity and severe pain in the post-anaesthesia care unit are all negatively associated with patient satisfaction. Of these factors, rebound pain occurs most frequently, being present in 52% (403/777) of our respondents.

Partnering with Palliative Care: A Case Report of Severe Pain in Critical Limb Ischemia Treated Successfully with a Continuous Popliteal Nerve Catheter

BACKGROUND

Critical limb ischemia (CLI) is limb pain occurring at rest or impending limb loss as a result of lack of blood flow to the affected extremity. CLI pain is challenging to control despite multimodal pharmacologic analgesia and surgical intervention. We described the successful use of a continuous local anesthetic infusion via a popliteal nerve catheter to control severe refractory ischemic lower limb pain in a patient who failed surgical intervention and performed a brief narrative literature review on regional anesthesia for ischemic pain. Case Presentation. A 74-year-old female with acute myelogenous leukemia presented with CLI after experiencing left popliteal artery occlusion. Palliative medicine service was consulted for pain management in the setting of escalating narcotic dose requirements. She experienced a complicated hospital course with several failed attempts at surgical revascularization due to arterial rethrombosis. In accordance with the patient's goals of care, a continuous popliteal nerve catheter was placed, despite the high risk nature of an intervention in an immunocompromised patient with thrombocytopenia (platelet count of 30,000 platelets/microliter) and ongoing therapeutic anticoagulation. The patient experienced immediate relief while transitioning to comfort care.

CONCLUSION

This is the first report of successful analgesia for CLI via a continuous popliteal catheter in a patient with rethrombosis and failed surgical revascularization. Based on our collaborative experience, we recommend the development of partnerships between the acute pain service and palliative care service to facilitate the early evaluation and decision to utilize regional anesthesia for treatment of CLI.

Molecular mechanisms of cold pain

The sensation of cooling is essential for survival. Extreme cold is a noxious stimulus that drives protective behaviour and that we thus perceive as pain. However, chronic pain patients suffering from cold allodynia paradoxically experience innocuous cooling as excruciating pain. Peripheral sensory neurons that detect decreasing temperature express numerous cold-sensitive and voltage-gated ion channels that govern their response to cooling in health and disease. In this review, we discuss how these ion channels control the sense of cooling and cold pain under physiological conditions, before focusing on the molecular mechanisms by which ion channels can trigger pathological cold pain. With the ever-rising number of patients burdened by chronic pain, we end by highlighting the pressing need to define the cells and molecules involved in cold allodynia and so identify new, rational drug targets for the analgesic treatment of cold pain.

Perineural local anaesthetic catheter after major lower limb amputation trial (PLACEMENT): results from a randomised controlled feasibility trial

OBJECTIVES

To determine the feasibility of undertaking a randomised controlled effectiveness trial evaluating the use of a perineural catheter (PNC) after major lower limb amputation with postoperative pain as the primary outcome.

DESIGN

Randomised controlled feasibility trial.

SETTING

Two vascular Centres in South Wales, UK.

PARTICIPANTS

50 patients scheduled for major lower limb amputation (below or above knee) for complications of peripheral vascular disease.

INTERVENTIONS

The treatment arm received a PNC placed adjacent to the sciatic or tibial nerve at the time of surgery, with continuous infusion of levobupivacaine hydrochloride 0.125% for up to 5 days. The control arm received neither local anaesthetic nor PNC. Both arms received usual perioperative anaesthesia and postoperative analgesia.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcomes were the proportion of eligible patients who were randomised and the proportion of recruited patients who provided primary effectiveness outcome data. Secondary outcomes were: the proportion of recruited patients reaching 2 and 6 month follow-up and supplying pain data; identification of key cost drivers; development of an economic analysis framework for a future effectiveness trial; identification of barriers to recruitment and site set-up; and identification of the best way to measure postoperative pain.

RESULTS

Seventy-six of 103 screened patients were deemed eligible over a 10 month period. Fifty (64.5%) of these patients were randomised, with one excluded in the perioperative period. Forty-five (91.3%) of 49 recruited patients provided enough pain scores on a 4-point verbal rating scale to allow primary effectiveness outcome evaluation. Attrition rates were high; 18 patients supplied data at 6 month follow-up. Costs were dominated by length of hospital stay. Patients and healthcare professionals reported that trial processes were acceptable.

CONCLUSIONS

Recruitment of patients into a trial comparing PNC use to usual care after major lower limb amputation with postoperative pain measured on a 4-point verbal rating scale is feasible. Evaluation of longer-term symptoms is difficult.

TRIAL REGISTRATION NUMBER

ISRCTN: 85 710 690. EudraCT: 2016-003544-37.

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

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

WITHDRAWN: Peripheral nerve blocks for postoperative pain after major knee surgery

BACKGROUND

Major knee surgery is a common operative procedure to help people with end-stage knee disease or trauma to regain mobility and have improved quality of life. Poorly controlled pain immediately after surgery is still a key issue for this procedure. Peripheral nerve blocks are localized and site-specific analgesic options for major knee surgery. The increasing use of peripheral nerve blocks following major knee surgery requires the synthesis of evidence to evaluate its effectiveness and safety, when compared with systemic, local infiltration, epidural and spinal analgesia.

OBJECTIVES

To examine the efficacy and safety of peripheral nerve blocks for postoperative pain control following major knee surgery using methods that permit comparison with systemic, local infiltration, epidural and spinal analgesia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 1, 2014), MEDLINE and EMBASE, from their inception to February 2014. We identified ongoing studies by searching trial registries, including the metaRegister of controlled trials (mRCT), clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP).

SELECTION CRITERIA

We included participant-blind, randomized controlled trials of adult participants (15 years or older) undergoing major knee surgery, in which peripheral nerve blocks were compared to systemic, local infiltration, epidural and spinal analgesia for postoperative pain relief.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and extracted data. We recorded information on participants, methods, interventions, outcomes (pain intensity, additional analgesic consumption, adverse events, knee range of motion, length of hospital stay, hospital costs, and participant satisfaction). We used the 5-point Oxford quality and validity scale to assess methodological quality, as well as criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We conducted meta-analysis of two or more studies with sufficient data to investigate the same outcome. We used the I² statistic to explore the heterogeneity. If there was no significant heterogeneity (I² value 0% to 40%), we used a fixed-effect model for meta-analysis, but otherwise we used a random-effects model. For dichotomous data, we present results as a summary risk ratio (RR) and a 95% confidence interval (95% CI). Where possible, we calculated the number needed to treat for an additional beneficial outcome (NNTB) or for an additional harmful outcome (NNTH), together with 95% CIs. For continuous data, we used the mean difference (MD) and 95% CI for similar outcome measures. We describe the findings of individual studies where pooling of data was not possible.

MAIN RESULTS

According to the eligibility criteria, we include 23 studies with 1571 participants, with high methodological quality overall. The studies compared peripheral nerve blocks adjunctive to systemic analgesia with systemic analgesia alone (19 studies), peripheral nerve blocks with local infiltration (three studies), and peripheral nerve blocks with epidural analgesia (one study). No study compared peripheral nerve blocks with spinal analgesia.Compared with systemic analgesia alone, peripheral nerve blocks adjunctive to systemic analgesia resulted in a significantly lower pain intensity score at rest, using a 100 mm visual analogue scale, at all time periods within 72 hours postoperatively, including the zero to 23 hours interval (MD -11.85, 95% CI -20.45 to -3.25, seven studies, 390 participants), the 24 to 47 hours interval (MD -12.92, 95% CI -19.82 to -6.02, six studies, 320 participants) and the 48 to 72 hours interval (MD -9.72, 95% CI -16.75 to -2.70, four studies, 210 participants). Subgroup analyses suggested that the high levels of statistical variation in our analyses could be explained by larger effects in people undergoing total knee arthroplasty compared with other types of surgery. Pain intensity was also significantly reduced on movement in the 48 to 72 hours interval postoperatively (MD -6.19, 95% CI -11.76 to -0.62, two studies, 112 participants). There was no significant difference on movement between these two groups in the time period of zero to 23 hours (MD -6.95, 95% CI -15.92 to 2.01, five studies, 304 participants) and 24 to 47 hours (MD -8.87, 95% CI -27.77 to 10.03, three studies, 182 participants). The included studies reported diverse types of adverse events, and we did not conduct a meta-analysis on specific types of adverse event. The numbers of studies and participants were also too few to draw conclusions on the other prespecified outcomes of: additional analgesic consumption; median time to remedication; knee range of motion; median time to ambulation; length of hospital stay; hospital costs; and participant satisfaction. There were insufficient data to compare peripheral nerve blocks and local infiltration or between peripheral nerve blocks and epidural analgesia.

AUTHORS' CONCLUSIONS

All of the included studies reported the main outcome of pain intensity but did not cover all the secondary outcomes of interest. The current review provides evidence that the use of peripheral nerve blocks as adjunctive techniques to systemic analgesia reduced pain intensity when compared with systemic analgesia alone after major knee surgery. There were too few data to draw conclusions on other outcomes of interest. More trials are needed to demonstrate a significant difference when compared with local infiltration, epidural analgesia and spinal analgesia.

An in Vivo Mouse Model to Investigate the Effect of Local Anesthetic Nanomedicines on Axonal Conduction and Excitability

Peripheral nerve blocks (PNBs) using local anesthetic (LA) are superior to systemic analgesia for management of post-operative pain. An insufficiently short PNB duration following single-shot LA can be optimized by development of extended release formulations among which liposomes have been shown to be the least toxic. In vivo rodent models for PNB have focused primarily on assessing behavioral responses following LA. In a previous study in human volunteers, we found that it is feasible to monitor the effect of LA in vivo by combining conventional conduction studies with nerve excitability studies. Here, we aimed to develop a mouse model where the same neurophysiological techniques can be used to investigate liposomal formulations of LA in vivo. To challenge the validity of the model, we tested the motor PNB following an unilamellar liposomal formulation, filled with the intermediate-duration LA lidocaine. Experiments were carried out in adult transgenic mice with fluorescent axons and with fluorescent tagged liposomes to allow in vivo imaging by probe-based confocal laser endomicroscopy. Recovery of conduction following LA injection at the ankle was monitored by stimulation of the tibial nerve fibers at the sciatic notch and recording of the plantar compound motor action potential (CMAP). We detected a delayed recovery in CMAP amplitude following liposomal lidocaine, without detrimental systemic effects. Furthermore, CMAP threshold-tracking studies of the distal tibial nerve showed that the increased rheobase was associated with a sequence of excitability changes similar to those found following non-encapsulated lidocaine PNB in humans, further supporting the translational value of the model.

Low-concentration distal nerve blocks with 0.125% levobupivacaine versus systemic analgesia for ambulatory trapeziectomy performed under axillary block: a randomized controlled trial

BACKGROUND

Trapeziectomy is one of the most painful procedures in ambulatory surgery. This prospective randomized trial aimed to compare postoperative pain control using distal peripheral nerve blocks (dPNB) with a low concentration of a long-acting local anesthetic versus conventional systemic analgesia.

METHODS

Fifty-two patients undergoing trapeziectomy were randomized to receive levobupivacaine 0.125% 5 mL on radial and median nerves at the elbow (dNB group), or not to receive these blocks (control group). In both groups, surgery was performed under axillary block (mepivacaine 1% 20 mL) and the same analgesic regimen was prescribed at discharge. The primary outcome was postoperative pain at 24 and 48 hours after surgery and maximum pain score on the first and second postoperative day. Secondary outcomes were duration of dPNB, rescue analgesia requirements, opioid-related side effects, consumption and effectiveness of antiemetic therapy, and upper limb motor block.

RESULTS

Fifty patients were analyzed. Maximum pain intensity was moderate to severe (dPNB vs. control) in 33.3% vs. 92.3% (P=0.002) on the first day after surgery and 20.8% vs. 80.8% (P<0.001) on the second day. The average duration of analgesia after dPNB was 10 hours and no patient reported motor block. dPNB reduced rescue analgesia requirements and the incidence of postoperative nausea and vomiting (PONV).

CONCLUSIONS

dPNB on target nerves provided better analgesia than systemic analgesia after trapeziectomy performed under axillary block. Opioid consumption and the incidence of PONV were lower in the dPNB group.

Perineural local anaesthetic catheter after major lower limb amputation trial (PLACEMENT): study protocol for a randomised controlled pilot study

Background

Pain after major lower limb amputation for peripheral arterial disease (PAD) is a significant problem. A perineural catheter (PNC) can be placed adjacent to the major nerve at the time of amputation with a continuous local anaesthetic infusion given postoperatively to try and reduce pain. Although low-quality observational data suggest that PNC usage reduces postoperative opioid requirements, there are limited data regarding its effect on pain. The aim of PLACEMENT is to explore the feasibility of running an effectiveness trial to assess the impact of a PNC with continuous local anaesthetic infusion, inserted at the time of amputation, on short and medium-term postoperative outcomes.

Methods/design

Fifty patients undergoing a major lower limb amputation (below or above the knee) for PAD will be recruited from two centres. Patients will be randomised in a 1:1 ratio to receive standard postoperative analgesia, with or without insertion of a PNC and local anaesthetic infusion for the first 5 postoperative days. Outcome data will be captured for the first 5 days, including pain scores (primary outcome, captured three times a day), opioid use, nausea or vomiting, itching, dizziness and complications. Patients will be contacted 2 and 6 months after surgery to assess quality of life, phantom limb pain, chronic stump pain and total healthcare costs. Semi-structured interviews will be conducted with at least 10 patients (dependent on saturation of analytic themes on preliminary coding) purposefully sampled to achieve variation in site and study arm. Interviews will explore patients’ perception of post-amputation pain and its treatment, and experience of study processes. Semi-structured interviews with 5–10 health professionals will explore feasibility, fidelity, and acceptability of the study. Data from this pilot will be used to assess feasibility of, and estimate parameters to calculate the sample size for an effectiveness trial. Full ethical approval has been granted (Wales Research Ethics Committee 3 reference number 16/WA/0353).

Discussion

PLACEMENT will be the first study to explore the feasibility of running an effectiveness trial on PNC usage for postoperative pain in amputees, and provide parameters to calculate the appropriate sample size for this study.

Trial registration

ISRCTN.com, ISRCTN85710690. Registered on 21 October 2016.

European Clinical Trials Database (EudraCT), 2016-003544-37. Registered on 24 August 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2357-x) contains supplementary material, which is available to authorized users.

Continuous femoral nerve blockade and single-shot sciatic nerve block promotes better analgesia and lower bleeding for total knee arthroplasty compared to intrathecal morphine: a randomized trial

Background

Knee arthroplasty leads to postoperative pain. This study compares analgesia and postoperative bleeding achieved by intrathecal morphine with a continuous femoral plus single-shot sciatic nerve block.

Methods

A randomized non-blinded clinical trial enrolled patients aged over 18 years old, ASA I to III who underwent total knee arthroplasty. All patients underwent spinal anesthesia with isobaric bupivacaine, 20 mg. One group received 100 mcg of intrathecal morphine (M group), and the other received a femoral nerve block by continuous infusion plus a "single shot" block of the sciatic nerve at the end of the surgery (FI group). Pain score from verbal numeric rating scale (VNRS) and morphine consumption during the first 72 h, as well as motor blockade, adverse effects, and postoperative bleeding were recorded. Analysis of variance of repeated measures with Bonferroni post-test, t-test and Fisher exact test were used for statistical analysis.

Results

Thirty nine patients completed the study (M = 20; FI = 19 patients) and were similar except for higher age in the FI group. Motor blockade as well as movement pain during postanesthesia care unit (PACU) staying were not different between the groups, but movement pain was significantly lower in FI group after 24 h. Postoperative bleeding (ml) was lower in FI group.

Conclusions

Continuous femoral nerve block combined with sciatic nerve block provides effective for postoperative analgesia in patients undergoing total knee arthroplasty, with lower pain scores after 24 h and a lower incidence of adverse effects and bleeding compared to intrathecal morphine.

Trial registration

Retrospectively registered on https://clinicaltrials.gov/ under identifier NCT02882152, 23^rd December, 2016.

Peripheral nerve blocks in shoulder arthroplasty: how do they influence complications and length of stay?

BACKGROUND

Regional anesthesia has proven to be a highly effective technique for pain control after total shoulder arthroplasty. However, concerns have been raised about the safety of upper-extremity nerve blocks, particularly with respect to the incidence of perioperative respiratory and neurologic complications, and little is known about their influence, if any, on length of stay after surgery.

QUESTIONS/PURPOSES

Using a large national cohort, we asked: (1) How frequently are upper-extremity peripheral nerve blocks added to general anesthesia in patients undergoing total shoulder arthroplasty? (2) Are there differences in the incidence of and adjusted risk for major perioperative complications and mortality between patients receiving general anesthesia with and without nerve blocks? And (3) does resource utilization (blood product transfusion, intensive care unit admission, length of stay) differ between groups?

METHODS

We searched a nationwide discharge database for patients undergoing total shoulder arthroplasty under general anesthesia with or without addition of a nerve block. Groups were compared with regard to demographics, comorbidities, major perioperative complications, and length of stay. Multivariable logistic regressions were performed to measure complications and resource use. A negative binomial regression was fitted to measure length of stay.

RESULTS

We identified 17,157 patients who underwent total shoulder arthroplasty between 2007 and 2011. Of those, approximately 21% received an upper-extremity peripheral nerve block in addition to general anesthesia. Patients receiving combined regional-general anesthesia had similar mean age (68.6 years [95% CI: 68.2-68.9 years] versus 69.1 years [95% CI: 68.9-69.3 years], p < 0.0043), a slightly lower mean Deyo (comorbidity) index (0.87 versus 0.93, p = 0.0052), and similar prevalence of individual comorbidities, compared to those patients receiving general anesthesia only. Addition of regional anesthesia was not associated with different odds ratios for complications, transfusion, and intensive care unit admission. Incident rates for length of stay were also similar between groups (incident rate ratio = 0.99; 95% CI: 0.97-1.02; p = 0.467) CONCLUSIONS: Addition of regional to general anesthesia was not associated with an increased complication profile or increased use of resources. In combination with improved pain control as known from previous research, regional anesthesia may represent a viable management option for shoulder arthroplasty. However, further research is necessary to better clarify the risk of neurologic complications.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Pain without nociceptors? Nav1.7-independent pain mechanisms

Nav1.7, a peripheral neuron voltage-gated sodium channel, is essential for pain and olfaction in mice and humans. We examined the role of Nav1.7 as well as Nav1.3, Nav1.8, and Nav1.9 in different mouse models of chronic pain. Constriction-injury-dependent neuropathic pain is abolished when Nav1.7 is deleted in sensory neurons, unlike nerve-transection-related pain, which requires the deletion of Nav1.7 in sensory and sympathetic neurons for pain relief. Sympathetic sprouting that develops in parallel with nerve-transection pain depends on the presence of Nav1.7 in sympathetic neurons. Mechanical and cold allodynia required distinct sets of neurons and different repertoires of sodium channels depending on the nerve injury model. Surprisingly, pain induced by the chemotherapeutic agent oxaliplatin and cancer-induced bone pain do not require the presence of Nav1.7 sodium channels or Nav1.8-positive nociceptors. Thus, similar pain phenotypes arise through distinct cellular and molecular mechanisms. Therefore, rational analgesic drug therapy requires patient stratification in terms of mechanisms and not just phenotype.

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Phenotypically identical pain models have different underlying molecular mechanisms

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Nav1.7 expression is required for sympathetic sprouting after neuronal damage

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Oxaliplatin and cancer-induced bone pain are both Nav1.7-independent

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Deleting Nav1.7 in adult mice reverses nerve damage-induced neuropathic pain

Peripheral nerve blocks for postoperative pain after major knee surgery

BACKGROUND

Major knee surgery is a common operative procedure to help people with end-stage knee disease or trauma to regain mobility and have improved quality of life. Poorly controlled pain immediately after surgery is still a key issue for this procedure. Peripheral nerve blocks are localized and site-specific analgesic options for major knee surgery. The increasing use of peripheral nerve blocks following major knee surgery requires the synthesis of evidence to evaluate its effectiveness and safety, when compared with systemic, local infiltration, epidural and spinal analgesia.

OBJECTIVES

To examine the efficacy and safety of peripheral nerve blocks for postoperative pain control following major knee surgery using methods that permit comparison with systemic, local infiltration, epidural and spinal analgesia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 1, 2014), MEDLINE and EMBASE, from their inception to February 2014. We identified ongoing studies by searching trial registries, including the metaRegister of controlled trials (mRCT), clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP).

SELECTION CRITERIA

We included participant-blind, randomized controlled trials of adult participants (15 years or older) undergoing major knee surgery, in which peripheral nerve blocks were compared to systemic, local infiltration, epidural and spinal analgesia for postoperative pain relief.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and extracted data. We recorded information on participants, methods, interventions, outcomes (pain intensity, additional analgesic consumption, adverse events, knee range of motion, length of hospital stay, hospital costs, and participant satisfaction). We used the 5-point Oxford quality and validity scale to assess methodological quality, as well as criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We conducted meta-analysis of two or more studies with sufficient data to investigate the same outcome. We used the I² statistic to explore the heterogeneity. If there was no significant heterogeneity (I² value 0% to 40%), we used a fixed-effect model for meta-analysis, but otherwise we used a random-effects model. For dichotomous data, we present results as a summary risk ratio (RR) and a 95% confidence interval (95% CI). Where possible, we calculated the number needed to treat for an additional beneficial outcome (NNTB) or for an additional harmful outcome (NNTH), together with 95% CIs. For continuous data, we used the mean difference (MD) and 95% CI for similar outcome measures. We describe the findings of individual studies where pooling of data was not possible.

MAIN RESULTS

According to the eligibility criteria, we include 23 studies with 1571 participants, with high methodological quality overall. The studies compared peripheral nerve blocks adjunctive to systemic analgesia with systemic analgesia alone (19 studies), peripheral nerve blocks with local infiltration (three studies), and peripheral nerve blocks with epidural analgesia (one study). No study compared peripheral nerve blocks with spinal analgesia.Compared with systemic analgesia alone, peripheral nerve blocks adjunctive to systemic analgesia resulted in a significantly lower pain intensity score at rest, using a 100 mm visual analogue scale, at all time periods within 72 hours postoperatively, including the zero to 23 hours interval (MD -11.85, 95% CI -20.45 to -3.25, seven studies, 390 participants), the 24 to 47 hours interval (MD -12.92, 95% CI -19.82 to -6.02, six studies, 320 participants) and the 48 to 72 hours interval (MD -9.72, 95% CI -16.75 to -2.70, four studies, 210 participants). Subgroup analyses suggested that the high levels of statistical variation in our analyses could be explained by larger effects in people undergoing total knee arthroplasty compared with other types of surgery. Pain intensity was also significantly reduced on movement in the 48 to 72 hours interval postoperatively (MD -6.19, 95% CI -11.76 to -0.62, two studies, 112 participants). There was no significant difference on movement between these two groups in the time period of zero to 23 hours (MD -6.95, 95% CI -15.92 to 2.01, five studies, 304 participants) and 24 to 47 hours (MD -8.87, 95% CI -27.77 to 10.03, three studies, 182 participants). The included studies reported diverse types of adverse events, and we did not conduct a meta-analysis on specific types of adverse event. The numbers of studies and participants were also too few to draw conclusions on the other prespecified outcomes of: additional analgesic consumption; median time to remedication; knee range of motion; median time to ambulation; length of hospital stay; hospital costs; and participant satisfaction. There were insufficient data to compare peripheral nerve blocks and local infiltration or between peripheral nerve blocks and epidural analgesia.

AUTHORS' CONCLUSIONS

All of the included studies reported the main outcome of pain intensity but did not cover all the secondary outcomes of interest. The current review provides evidence that the use of peripheral nerve blocks as adjunctive techniques to systemic analgesia reduced pain intensity when compared with systemic analgesia alone after major knee surgery. There were too few data to draw conclusions on other outcomes of interest. More trials are needed to demonstrate a significant difference when compared with local infiltration, epidural analgesia and spinal analgesia.

Femoral nerve block: Assessment of postoperative analgesia in arthroscopic anterior cruciate ligament reconstruction

BACKGROUND AND OBJECTIVES

Knee anterior cruciate ligament reconstruction (ACLR) may be painful in the postoperative period. The primary objective of this study was to evaluate whether the use of femoral nerve block (FNB) associated with spinal anesthesia would improve the postoperative pain treatment in ACLR and the secondary objectives were to evaluate tramadol request and adverse events.

METHOD

53 patients were randomly divided into two groups: GA (n =26) received spinal anesthesia and GB (n = 27) received spinal anesthesia and FNB. All patients received multimodal analgesia and rescue analgesics could be requested anytime. Assessments were performed at 6, 12 and 24 hours.

RESULTS

There was no difference between both groups regarding demographic and clinical- surgical variables. There was no difference between groups regarding pain intensity. Mean pain scores were higher at 12 hours in GA and there was no change in GB; 55.6% of patients reported moderate pain in GA and 53.8% mild pain in GB. There was no difference regarding tramadol request. There were no serious adverse events: 80.8% of patients in GB had motor block of the thigh and two fell.

CONCLUSIONS

Analgesia was more effective with the combination of spinal and FNB, which allowed better control of postoperative pain, assessed 12 hours after anesthesia. There was no difference in tramadol request. Patients in this study had no serious adverse events; however, one must be attentive to motor paralysis and the possibility of falling when FNB is performed.