Effects of gabapentin on morphine consumption and pain in severely burned patients

Effectiveness and Adverse Events of Gabapentinoids as Analgesics for Patients with Burn Injuries: A Systematic Review with Meta-Analysis and Trial Sequential Analysis

(1) Background: Pain after a burn injury is difficult to endure, and emerging studies aim to ascertain the effects of gabapentin and pregabalin as non-opioid treatment options. (2) Methods: We searched for randomised controlled trials (RCTs) in six databases. The risk of bias was assessed using the RoB 2.0 tool. We performed meta-analysis and trial sequential analysis and used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology for judging the certainty of evidence (CoE). (3) Results: Five RCTs were included. Compared with placebo, gabapentinoids significantly decreased the pain intensity within 24 h (mean difference (MD) = -1.06, 95% confidence interval (CI): -1.47--0.65) and from 72 h to 9 days (MD = -0.82, 95% CI: -1.16--0.48), but not after 3 weeks (MD = -0.44, 95% CI: -1.31-0.42). Opioid consumption (mg/day) was reduced within 24 h (MD = -13.34, 95% CI: -22.16--4.52) and from 72 h to 9 days (MD = -7.87, 95% CI: -14.82--0.91). Increased risks of drowsiness (risk ratio (RR) = 3.255, 95% CI: 1.135-9.335) and dizziness (RR = 3.034, 95% CI: 1.006-9.147) were observed, but sensitivity analysis using the Bayesian method showed no increased risk. All endpoints were judged as low to very low CoE. (4) Conclusions: Gabapentinoids offer modest analgesic benefits as a component of multimodal pain management for burn injuries of less than 3 weeks. The adverse effects should be carefully monitored. Large-scale RCTs are warranted for the reinforcement of CoE in clinical use.

Multifactorial pathways in burn injury-induced chronic pain: novel targets and their pharmacological modulation

Burn injuries are among the highly prevalent medical conditions worldwide that occur mainly in children, military veterans and victims of fire accidents. It is one of the leading causes of temporary as well as permanent disabilities in patients. Burn injuries are accompanied by pain that persists even after recovery from tissue damage which puts immense pressure on the healthcare system. The pathophysiology of burn pain is poorly understood due to its complex nature and lack of considerable preclinical and clinical shreds of evidence, that creates a substantial barrier to the development of new analgesics. Burns damage the skin layers supplied with nociceptors such as NAV1.7, TRPV1, and TRPA1. Burn injury-mediated co-localization and simultaneous activation of TRPA1 and TRPV1 in nociceptive primary afferent C-fibers which contributes to the development and maintenance of chronic pain. Burn injuries are accompanied by central sensitization, a key feature of pain pathophysiology mainly driven by a series of cascades involving aberrations in the glutamatergic system, microglial activation, release of neuropeptides, cytokines, and chemokines. Activation of p38 mitogen-activated protein kinase, altered endogenous opioid signaling, and distorted genomic expression are other pathophysiological factors responsible for the development and maintenance of burn pain. Here we discuss comprehensive literature on molecular mechanisms of burn pain and potential targets that could be translated into near future therapeutics.

Prescribing of Gabapentinoids with or without opioids after burn injury in the US, 2012-2018

Burn injury pain manifests as a combination of inflammatory, nociceptive, and neuropathic features. While opioids are the mainstay of burn pain management, non-opioid medications, such as gabapentinoids, have also been considered as they target the central nervous system. Increased opioid adverse events and overdose deaths in the United States led to the 2014 and 2016 guidelines to reduce opioid prescribing and consider alternatives, such as gabapentinoids. In the context of burn, the rate of gabapentinoid prescribing at the national level is unknown and it is unclear whether any shift has occurred in prescribing practices over time. We conducted a population level cohort study of adult burn patients from 2012 to 2018 to evaluate the rates and determinants of gabapentinoid prescribing, with and without opioids. Of 98,001 patients with burn, 22,521 (22.98%) received opioids and/or gabapentinoids (GABA). GABA represented 2.4% of prescriptions in 2012, but increased to 7.2% by 2018, while GABA-opioid co-prescriptions increased from 2.3% to 5.1%. The rate of increase in GABA prescriptions was higher for those aged 50-65 years or residing in the South. After adjustment, GABA was 44% more likely to be prescribed in 2017 and 2018 compared to 2012 and 2013, opioids were 38% less likely, while co-prescribing did not show a statistically significant change. Our study showed a modest increase in gabapentinoids' outpatient prescribing for burn patients after the 2014 and 2016 guidelines, indicating more opportunities for prescribers to expand non-opioid pain management in this population.

Evaluation of antihyperalgesic and analgesic effects of 35% nitrous oxide when combined with remifentanil: A randomised phase 1 trial in volunteers

BACKGROUND

Remifentanil is an effective drug in peri-operative pain therapy, but it can also induce and aggravate hyperalgesia. Supplemental administration of N2O may help to reduce remifentanil-induced hyperalgesia.

OBJECTIVE

To evaluate the effect of 35 and 50% N2O on hyperalgesia and pain after remifentanil infusion.

DESIGN

Single site, phase 1, double-blind, placebo-controlled, randomised crossover study.

SETTING

University Hospital, Germany from January 2012 to April 2012.

PARTICIPANTS

Twenty-one healthy male volunteers.

INTERVENTIONS

Transcutaneous electrical stimulation induced spontaneous acute pain and stable areas of hyperalgesia. Each volunteer underwent the following four sessions in a randomised order: 50 to 50% N2-O2 and intravenous (i.v.) 0.9% saline infusion (placebo); 50 to 50% N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (remifentanil); 35 to 15 to 50% N2O-N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (tested drug) and 50 to 50% N2O-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (gas active control). Gas mixtures were inhaled for 60 min; i.v. drugs were administered for 30 min.

MAIN OUTCOME MEASURES

Areas of pin-prick hyperalgesia, areas of touch-evoked allodynia and pain intensity on a visual analogue scale were assessed repeatedly for 160 min.

RESULTS

Data from 20 volunteers were analysed. There were significant treatment and treatment-by-time effects regarding areas of hyperalgesia (P < 0.001). After the treatment period, the area of hyperalgesia was significantly reduced (P < 0.001) in the tested drug and in the gas active control (30.6 ± 9.25 and 24.4 ± 7.3 cm2, respectively) compared with remifentanil (51.0 ± 17.0 cm2). There was also a significant difference between the gas active control and the tested drug sessions (P < 0.001). For the area of allodynia and pain rating, results were consistent with the results for hyperalgesia.

CONCLUSIONS

Administration of 35% N2O significantly reduced hyperalgesia, allodynia and pain intensity induced after remifentanil. It might therefore be suitable in peri-operative pain relief characterised by hyperalgesia and allodynia, such as postoperative pain, and may help to reduce opioid demand.

TRIAL REGISTRATION

EudraCT-No.: 2011-000966-37.

Neuropathic agents in the management of pruritus in burn injuries: a systematic review and meta-analysis

Objectives

Pruritus is a common and often distressing complication after a burn injury. The purpose of this review is to explore the efficacy of drugs classically used to treat neuropathic pain in the management of pruritus after burn injury.

Methods

A systematic literature search of medical databases was conducted to find studies investigating drugs listed in the National Institute for Health and Care Excellence (NICE) guideline (CG173, "neuropathic pain in adults") for the management of pruritus after burn injury in patients of any age. Controlled studies were stratified by the drug class studied and their risk of bias before conducting meta-analysis. A narrative review of case series or observational studies was presented. Severity of pruritus at any time point, with all quantitative and qualitative measures, was included.

Results

Fifteen studies were included in the final analysis, 10 investigated the use of gabapentinoids, 4 studied doxepin, and 1 local anesthetic agents. Meta-analysis of three randomized controlled trials (RCTs) demonstrated that the use of gabapentinoids was associated with an improvement in mean VAS (Visual Analog Scale) 0-10 scores of 2.96 (95% confidence interval (95% CI) 1.20 to 4.73, p<0.001) when compared with placebo or antihistamine. A meta-analysis of four RCTs investigating topical doxepin showed an improvement in mean VAS scores of 1.82 (95% CI 0.55 to 3.09, p<0.001). However, when excluding two studies found to be at high risk of bias, no such improvement was found (-0.32, 95% CI -1.64 to -0.99, p=0.83).

Conclusion

This study suggests that gabapentinoids are beneficial in the management of burn-related pruritus. There is a lack of evidence to suggest that doxepin is an effective treatment. Topical local anesthetic agents may be safe and beneficial, but studies are scarce.

Level of evidence

Systematic review, level II.

Comparing the Effect of Gabapentin, Ketamine, Dexmedetomidine, and Entonox on Pain Control in Burn Wound Dressing

This study aimed to evaluate differences in the experience of pain, nausea, and vomiting, as well as the hemodynamic parameters including heart rate (HR) and blood pressure (BP) in burn patients across four pain treatment groups-i.e., gabapentin, ketamine, dexmedetomidine, and entonox. In a single blinded randomized comparative study, 25 burn patients with second- or third-degree burns between 20% and 50% of their body surface were assigned to different treatment groups by using block randomization, while keeping the investigator blind to the size of the block. We recorded demographics, the hemodynamics, adverse effects, and pain levels before the treatment and again 5, 10, 15, 30, 60, 120, 240, and 360 minutes postadministration of pain medication (after-treatment). Gabapentin ketamine, dexmedetomidine, and entonox had significant effects in treatment of pain in burn patients. Entonox had the best analgesic effect with the least adverse effects and hemodynamic changes. Gabapentin also had good pain management effects; however, it showed less desirable effects on hemodynamic variables. Entonox caused the least amount of hemodynamic changes and the least adverse reactions, but since the medication is delivered by a facemask it limited its application with our patients. Gabapentin offered good benefits but caused a gradual drop in BP and HR and had some unfavorable reactions. However, since it is administered orally and often is cheaper, it could be considered as the drug of choice.

PREVALENCE, TREATMENT, AND SURVIVAL OF BURNED WILDLIFE PRESENTING TO REHABILITATION FACILITIES FROM 2015 TO 2018

In recent decades, wildfires have increased in frequency and geographic scale across the globe. The human health implications and ecological succession after wildfires are well documented and studied, but there is a lack of empirical research about the direct effects of wildfires on wildlife. Recent wildfires have demonstrated the need to better understand animal burn injuries and innovations in veterinary burn treatment. An online survey was distributed to wildlife rehabilitation facilities internationally to collect baseline information about the number and type of burned wildlife cases admitted, treatments used, and survivorship of wildlife affected by wildfires. Approximately 80% (n = 49) of all respondents (n = 61) reported admitting cases of burned wildlife from 2015 to 2018. Respondents included facilities from six different countries and roughly 43% of facilities reported having a veterinarian on staff. Electrical burns were most commonly reported with 89% of respondents stating that they had seen electrical burns while 38% of respondents reported seeing wildfire-source thermal burns in wildlife patients. Respondents were asked about their frequency of use of different treatment methods. Bandages, colloid fluids, and opioids were used at significantly higher rates at facilities with veterinarians compared with facilities that did not report having a veterinarian; however, survival of burned wildlife patients did not significantly differ based on the factor of having a veterinarian on staff. Long-term and short-term complications were commonly reported for wildlife burn patients; 88% of facilities reported scarring, 81% reported alopecia, and 61% reported sepsis. Burned animals admitted to facilities were reported to have equal odds of dying and surviving. Burn care recommendations have changed considerably in recent decades. This study provided a unique opportunity to compare contemporary recommendations in human medicine with current methods used in wildlife rehabilitation facilities to identify potential areas of further investigation and improvement for wildlife medicine.

Impact of Multimodal Analgesia in Critically Ill Burn Patients

Opioids are the mainstay of treatment for burn pain. However, these medications may be associated with, respiratory depression, and dependence. Multimodal analgesia is an alternative method that utilizes both opioid and non-opioid medications with different mechanisms. This study examines the impact of multimodal therapy for post-operative pain control in a burn intensive care unit.This was a retrospective cohort study of patients admitted to the burn unit at a tertiary medical center. Consecutively admitted patients with burns greater than or equal to 10% total body surface area and intensive care unit length of stay greater than seven days were eligible for inclusion (2012 - 2018). Patients were excluded if they received an opioid infusion greater than 48 hours.  Patients treated with multimodal analgesia were compared to those treated with opioids alone. Data was calculated for 5 days after surgery. There were 98 patients in the non-multimodal group and 97 in the multimodal group. . Mean cumulative opioid dose was lower in the multimodal group (1,028.7 mg vs. 1,423.2 mg, P = 0.0031). Patients with greater than 20% burns had a larger reduction in mean opioid equivalents in the multimodal group (1,106 vs 1,594 mg, P=0.009) compared to patients with burns less than 20% (940 vs. 1,282 mg, P=0.058). There was no difference in mean pain scores on post-operative day 5 (6.2 + 2.2 vs. 5.5 + 2.3 P=0.07) or at intensive care unit discharge (4.7 + 2.4 vs 4.7 + 2.8, P=0.99). The use of multimodal analgesia significantly reduced cumulative opioid equivalent dose without compromising pain control.    .

The Management of Burn Pain in a Pediatric Burns-Specialist Hospital

Appropriate pain management for children who have experienced an acute burn injury is critical to improve patient outcomes and reduce potential morbidities. With 60% of our patients being under the age of 4 years, pain management is crucial in reducing pain and anxiety in both patients and parents. It is imperative that appropriate pain relief is commenced from initial contact with healthcare workers as this will affect the success or failure of future wound procedures. Uncontrolled pain can negatively affect a patient, both short and long term. It may cause anticipatory anxiety for future medical procedures, increased pain and anxiety can decrease wound re-epithelialization which can lead to long-term consequences for growth and mobility, and increased pain can also influence the possibility of patients and families displaying signs of post-traumatic stress disorder. Pain management in the form of pharmaceuticals is imperative during burn wound treatment and should incorporate pain relief targeted at both background and procedural pain. It also requires a multimodal, individualized, and targeted approach combining both pharmaceutical and nonpharmaceutical techniques, including cold running water, multimodal distraction devices, hypnotherapy, and bubbles. We discuss the research and knowledge that our center has gained through treating pediatric patients with burns over the last 20 years.

Palliation, end-of-life care and burns; practical issues, spiritual care and care of the family - A narrative review II

Palliative care is the turn from cure as the priority of care to symptom relief and comfort care. Although very little is published in the burn literature on palliative care, guidelines can be gleaned from the general literature on palliative care, particularly for acute surgical and critical care patients. This second article discusses practical issues around palliative care for burn patients, such as pain and fluid management, withdrawal of ventilator support and wound care, as well as spiritual and family issues. This paper forms part two, of two narrative reviews on the topic of palliation, end-of-life care and burns. The first part considered concepts, decision-making and communication. It was published in volume 10, issue 2, June 2020, pages 95–98.

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Mortality of burns presented to a burns unit in Africa is about 10%.

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Resources in Africa to manage burn patients are scarce and patients with massive burns may not be offered curative burn care.

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There are no guidelines for palliative care in burn patients.

American Burn Association Guidelines on the Management of Acute Pain in the Adult Burn Patient: A Review of the Literature, a Compilation of Expert Opinion, and Next Steps

The ABA pain guidelines were developed 14 years ago and have not been revised despite evolution in the practice of burn care. A sub-committee of the American Burn Association's Committee on the Organization and Delivery of Burn Care was created to revise the adult pain guidelines. A MEDLINE search of English-language publications from 1968 to 2018 was conducted using the keywords "burn pain," "treatment," and "assessment." Selected references were also used from the greater pain literature. Studies were graded by two members of the committee using Oxford Centre for Evidence-based Medicine-Levels of Evidence. We then met as a group to determine expert consensus on a variety of topics related to treating pain in burn patients. Finally, we assessed gaps in the current knowledge and determined research questions that would aid in providing better recommendations for optimal pain management of the burn patient. The literature search produced 189 papers, 95 were found to be relevant to the assessment and treatment of burn pain. From the greater pain literature 151 references were included, totaling 246 papers being analyzed. Following this literature review, a meeting to establish expert consensus was held and 20 guidelines established in the areas of pain assessment, opioid medications, nonopioid medications, regional anesthesia, and nonpharmacologic treatments. There is increasing research on pain management modalities, but available studies are inadequate to create a true standard of care. We call for more burn specific research into modalities for burn pain control as well as research on multimodal pain control.

Analgesic use in contemporary burn practice: Applications to burn mass casualty incident planning

BACKGROUND

Determining the amount of analgesics required will help burn centers improve their ability to plan for a burn mass casualty incident (BMCI). We sought to quantify the amount of analgesics needed in an inpatient burn population. We hoped that assessing the analgesic use in daily burn care practice will potentially help estimate opioid needs in a burn mass casualty incident (BMCI).

METHODS

We included patients with burns covering equal to or less than 30% total body surface area (TBSA), admitted from spring 2013 to spring 2015. Patient records were reviewed for analgesics and adjuncts, pain scores, age and TBSA. The doses of the different opioids administered were converted into morphine equivalent doses (MED).

RESULTS

We enrolled 141 acute burn survivors with a mean TBSA of 8.2±0.6%. The lowest daily average MED per person was 24.6±2.0mg MED, recorded on the day of injury. The daily average MED per person increased until it peaked at 52.5±5.6mg MED at day 8 post-burn. Then, it declined to 24.6±3.4mg MED by day 14. Bivariate regression analysis of average MED by TBSA showed a significant positive correlation (p<0.001). The analysis of average MED by age showed a significant negative correlation (p<0001).

CONCLUSION

Our study quantified opioid requirements in an inpatient burn population and identified TBSA (positively) and age (negatively) as significant predictors.

Why mu-opioid agonists have less analgesic efficacy in neuropathic pain?

Injury to peripheral nerves often leads to abnormal pain states (hyperalgesia, allodynia and spontaneous pain), which can remain long after the injury heals. Although opioid agonists remain the gold standard for the treatment of moderate to severe pain, they show reduced efficacy against neuropathic pain. In addition to analgesia, opioid use is also associated with hyperalgesia and analgesia tolerance, whose underlying mechanisms share some commonalities with nerve injury-induced hypersensitivity. Here, we reviewed up-to-day research exploring the contribution of mu-opioid receptor (MOR) on the pathophysiology of neuropathic pain and on analgesic opioid actions under these conditions. We focused on the specific contributions of MOR populations at peripheral, spinal and supraspinal level. Moreover, evidences of neuroplastic changes that may underlie the low efficacy of MOR agonists under neuropathic pain conditions are reviewed and discussed. Sensitization processes leading to pain hypersensitivity, molecular changes in signalling pathways triggered by MOR and glial activation are some of these mechanisms elicited by both nerve injury and opioid exposure. Nerve injury-induced pain hypersensitivity might be masking the initial analgesic effects of opioid agonists, and alternatively, sustained opioid treatment to individuals already suffering from neuropathic pain could aggravate their pathophysiological state. Finally, some combined therapies that can increase opioid analgesic effectiveness in neuropathic pain treatment are highlighted. SIGNIFICANCE: This review provides evidence of the low benefit of opioid monotherapy in neuropathic pain and analyses the reasons of this reduced effectiveness. Opioid agonists along with drugs targeted to block the sensitization processes induced by MOR stimulation might result in a better management of neuropathic pain.

Pain Management in Pediatric Burn Patients: Review of Recent Literature and Future Directions

Childhood burns are a profoundly traumatic and painful experience. Despite recognition of the prevalence of burn injuries in children and the severity of the associated pain, burn pain remains undertreated. At the same time, more evidence is emerging to suggest that undertreated pain has serious long-term medical and psychiatric consequences, many of which can be ameliorated with improved pain control. Pain in burn patients is, however, notoriously difficult to treat, perhaps because there is a chronic pain aspect underlying the acute pain that accompanies wound care and procedures. This difficulty is compounded by the fact that there are little data to guide decision making in these patients. This article aims to identify the best strategies to guide clinical practice through a review of the past 10 years' development in pediatric burn pain management. However, because clinical investigations remain limited in burned children, we also aim to draw attention to those areas where the data do not identify an optimal approach and further work is needed. Overall, in addition to just the traditional pharmacological approaches to pain, such as acetaminophen, benzodiazepines, and opioids, there is growing evidence to support more widespread use of regional anesthesia and novel technologies such as virtual reality. Starting with an improved understanding of the current state of the literature, we can identify areas of research and important questions whose answers will ultimately improve care and reduce suffering for this unfortunate population of children.

Patient-controlled analgesia for background pain of major burn injury

BACKGROUND

Studies have suggested that intravenous patient-controlled analgesia (IV-PCA) can be used safely for the treatment of background pain in burn patients. However, no comprehensive protocols have been published. How patient or surgical factors correlate with the amount of opioid consumption remains unclear. The aim of this study is to provide an IV-PCA protocol for alleviating pain for burn injuries, and to assess factors correlated with opioid consumption.

METHODS

At the Mackay Memorial Hospital, a retrospective analysis from June 27th to October 31st of 2015 was carried out to investigate the use of IV-PCA in relation to the demographic and clinical data of patients who suffered from burn injuries due to a massive explosion of flammable powder. A standardized morphine IV-PCA protocol with rapid escalation was implemented. Variables assessed included age, weight, gender, days of usage, total surface area burned (TBSAB) and operations.

RESULTS

Among the 23 patients who received IV-PCA for burn pain control, it was noted that the larger the TBSAB and the higher the visual analogue scale (VAS), the more amount of morphine was consumed. Correlations between morphine consumption positively with weight (P < 0.01), female gender (P < 0.01), severity of injury (P = 0.01), and negatively with receiving operations (P = 0.01) were statistically significant.

CONCLUSION

As the daily morphine consumption was positively correlated with TBSAB, VAS, weight, female gender, the use of our IV-PCA protocol was sufficient in the management of background pain for patients with major burn injury.

Remifentanil-induced postoperative hyperalgesia: current perspectives on mechanisms and therapeutic strategies

The use of remifentanil in clinical practice offers several advantages and it is used for a wide range of procedures, ranging from day-surgery anesthesia to more complex procedures. Nonetheless, remifentanil has been consistently linked with development of opioid-induced hyperalgesia (OIH), which is described as a paradoxical increase in sensitivity to painful stimuli that develops after exposure to opioid treatment. The development of OIH may cause several issues, delaying recovery after surgery and preventing timely patient's discharge. Moreover, it causes patient's discomfort with higher pain scores, greater use of analgesics, and associated side effects. Remifentanil is the opioid most convincingly associated with OIH, and hereby we provide a review of remifentanil-induced hyperalgesia, describing both the underlying mechanisms involved and the available studies investigating experimental and clinical pharmacologic approaches aiming at reducing its incidence and degree.

Burn injury: Challenges and advances in burn wound healing, infection, pain and scarring

Severe burn injuries are the most traumatic and physically debilitating injuries affecting nearly every organ system and leading to significant morbidity and mortality. Early burn wound excision and skin grafting are common clinical practices that have significantly improved the outcomes for severe burn injured patients by reducing mortality rate and days of hospital stay. However, slow wound healing, infection, pain, and hypertrophic scarring continue to remain a major challenge in burn research and management. In the present article, we review and discuss issues in the current treatment of burn injuries; the advances and novel strategies developed in the past decade that have improved burn management; and also, pioneer ideas and studies in burn research which aims to enhance burn wound care with a focus on burn wound infection, pain management, treatments for scarring and skin tissue engineering.

Principles of Burn Pain Management

This article describes pathophysiology of burn injury-related pain and the basic principles of burn pain management. The focus is on concepts of perioperative and periprocedural pain management with extensive discussion of opioid-based analgesia, including patient-controlled analgesia, challenges of effective opioid therapy in opioid-tolerant patients, and opioid-induced hyperalgesia. The principles of multimodal pain management are discussed, including the importance of psychological counseling, perioperative interventional pain procedures, and alternative pain management options. A brief synopsis of the principles of outpatient pain management is provided.

Transcriptomic and behavioural characterisation of a mouse model of burn pain identify the cholecystokinin 2 receptor as an analgesic target

Burn injury is a cause of significant mortality and morbidity worldwide and is frequently associated with severe and long-lasting pain that remains difficult to manage throughout recovery. We characterised a mouse model of burn-induced pain using pharmacological and transcriptomic approaches. Mechanical allodynia elicited by burn injury was partially reversed by meloxicam (5 mg/kg), gabapentin (100 mg/kg) and oxycodone (3 and 10 mg/kg), while thermal allodynia and gait abnormalities were only significantly improved by amitriptyline (3 mg/kg) and oxycodone (10 mg/kg). The need for relatively high opioid doses to elicit analgesia suggested a degree of opioid resistance, similar to that shown clinically in burn patients. We thus assessed the gene expression changes in dorsal root ganglion neurons and pathophysiological mechanisms underpinning burn injury-induced pain using a transcriptomic approach. Burn injury was associated with significantly increased expression of genes associated with axon guidance, neuropeptide signalling, behavioural defence response and extracellular signalling, confirming a mixed neuropathic and inflammatory aetiology. Notably, among the pain-related genes that were upregulated post-injury was the cholecystokinin 2 receptor (Cckbr), a G protein-coupled receptor known as a pain target involved in reducing opioid effectiveness. Indeed, the clinically used cholecystokinin receptor antagonist proglumide (30 mg/kg) was effective at reversing mechanical allodynia, with additional analgesia evident in combination with low-dose oxycodone (1 mg/kg), including significant reversal of thermal allodynia. These findings highlight the complex pathophysiological mechanisms underpinning burn injury-induced pain and suggest that cholecystokinin-2 receptor antagonists may be useful clinically as adjuvants to decrease opioid requirements and improve analgesic management.

Progress of clinical practice on the management of burn-associated pain: Lessons from animal models

Opioid-based analgesics provide the mainstay for attenuating burn pain, but they have a myriad of side effects including respiratory depression, nausea, impaired gastrointestinal motility, sedation, dependence, physiologic tolerance, and opioid-induced hyperalgesia. To test and develop novel analgesics, validated burn-relevant animal models of pain are indispensable. Herein we review such animal models, which are mostly limited to rodent models of burn-induced, inflammatory, and neuropathic pain. The latter two are pain syndromes that provide insight into the pain caused by systemic pro-inflammatory cytokines and direct injury to nerves (e.g., after severe burn), respectively. To date, no single animal model optimally mimics the complex pathophysiology and pain that a human burn patient experiences. No currently available burn-pain model examines effects of pharmacological intervention on wound healing. As cornerstones of pain and wound healing, pro-inflammatory mediators may be utilized for insight into both processes. Moreover, common clinical concerns such as systemic inflammatory response syndrome and multiple organ dysfunction remain unaddressed. For development of analgesics, these aberrations can significantly alter the potential efficacy and/or adverse effects of a prescribed analgesic following burn trauma. We therefore suggest that a multi-model strategy would be the most clinically relevant when evaluating novel analgesics for use in burn patients.

Pain and the thermally injured patient-a review of current therapies

Thermally injured patients experience tremendous pain from the moment of injury to months or years after their discharge from the hospital. Pain is therefore a critical component of proper management of burns. Although the importance of pain is well recognized, it is often undertreated. Acute uncontrolled pain has been shown to increase the incidence of mental health disorders and increase the incidence of suicide after discharge. Long-term poor pain control leads to an increase in the incidence of persistent pain. Most burn centers have used opioids as the mainstay analgesic, but recently, the significant side effects of opioids have led to the implementation of new and combined therapeutics. Pharmacological agents such as gabapentin, clonidine, dexmedetomidine, and ketamine have all been suggested as adjuncts to opioids in the treatment of burn pain. Nonpharmacological therapies such as hypnosis, virtual reality devices, and behavioral therapy are also essential adjuncts to current medications. This review aims at identifying the currently available pharmacological and nonpharmacological options for optimal pain management in the adult burn population.

Evidence and consensus based guideline for the management of delirium, analgesia, and sedation in intensive care medicine. Revision 2015 (DAS-Guideline 2015) - short version

In 2010, under the guidance of the DGAI (German Society of Anaesthesiology and Intensive Care Medicine) and DIVI (German Interdisciplinary Association for Intensive Care and Emergency Medicine), twelve German medical societies published the “Evidence- and Consensus-based Guidelines on the Management of Analgesia, Sedation and Delirium in Intensive Care”. Since then, several new studies and publications have considerably increased the body of evidence, including the new recommendations from the American College of Critical Care Medicine (ACCM) in conjunction with Society of Critical Care Medicine (SCCM) and American Society of Health-System Pharmacists (ASHP) from 2013. For this update, a major restructuring and extension of the guidelines were needed in order to cover new aspects of treatment, such as sleep and anxiety management. The literature was systematically searched and evaluated using the criteria of the Oxford Center of Evidence Based Medicine. The body of evidence used to formulate these recommendations was reviewed and approved by representatives of 17 national societies. Three grades of recommendation were used as follows: Grade “A” (strong recommendation), Grade “B” (recommendation) and Grade “0” (open recommendation). The result is a comprehensive, interdisciplinary, evidence and consensus-based set of level 3 guidelines. This publication was designed for all ICU professionals, and takes into account all critically ill patient populations. It represents a guide to symptom-oriented prevention, diagnosis, and treatment of delirium, anxiety, stress, and protocol-based analgesia, sedation, and sleep-management in intensive care medicine.

Opioid-induced hyperalgesia in chronic pain patients and the mitigating effects of gabapentin

Chronic pain patients receiving opioid drugs are at risk for opioid-induced hyperalgesia (OIH), wherein opioid pain medication leads to a paradoxical pain state. OIH involves central sensitization of primary and secondary afferent neurons in the dorsal horn and dorsal root ganglion, similar to neuropathic pain. Gabapentin, a gamma-aminobutyric acid (GABA) analog anticonvulsant used to treat neuropathic pain, has been shown in animal models to reduce fentanyl hyperalgesia without compromising analgesic effect. Chronic pain patients have also exhibited lower opioid consumption and improved pain response when given gabapentin. However, few human studies investigating gabapentin use in OIH have been performed in recent years. In this review, we discuss the potential mechanisms that underlie OIH and provide a critical overview of interventional therapeutic strategies, especially the clinically-successful drug gabapentin, which may reduce OIH.

Gabapentin is ineffective as an analgesic adjunct in the immediate postburn period

Successful treatment of burn pain requires a multimodality approach. Although opioid agents are the mainstay, other nonopioid agents, such as anticonvulsants, are frequently employed for pain control, with unknown benefits. The authors sought to determine the efficacy of gabapentin in acute burn pain management. Patients admitted to the burn center with burns more than 5% total body surface area and expected length of stay more than 48 hours were randomized and prospectively enrolled in this double-blind, placebo-controlled study from February 2010 to September 2011. Drug escalation and titration were done by protocol. Pain was assessed by unit protocol with the Numeric Rating Scale. Neuropathic pain and anxiety were recorded at least biweekly. Psychosocial adjustment was assessed at follow-up. Opioid medications were converted to morphine equivalents. Differences between pain levels and opioid consumption were analyzed between groups with the Student's t-test and χ test, respectively. The study was designed to detect a difference of 22% in opioid use between the two study groups with an enrollment of 50 patients with α of 0.05 and β of 80%. P < .5 was considered significant. Fifty-three patients consented for the study and received the loading dose. Four patients withdrew. Both an intention-to-treat and actual treatment analysis were performed on all 53 patients. The placebo and drug populations were well matched for demographic variables, body surface area burned, and need for surgical intervention. The average length of stay was 11 ± 6.8 days and did not vary between groups. The study drug group received 10.8 ± 0.67 days of study drug, with eight patients receiving a dosage of 300 mg thrice daily (TID), 24 receiving 600 mg TID, 14 receiving 800 mg TID, and seven receiving 1200 mg TID. The incidence of neuropathic pain was 39% in the study drug arm and 38% in the placebo group. Neither pain scores (rest and procedural) nor opioid consumption differed between the groups. Forty-three patients (81.1%) were assessed at their first clinic visit. There was no difference in psychosocial functioning in either treatment group. In this randomized, double-blind, placebo-controlled study, the use of gabapentin in acute burn pain management did not decrease pain scores or lessen opioid requirements. Further research into nonopioid alternatives for burn pain analgesia is needed.

Pain management in burn patients

BACKGROUND AND OBJECTIVES

Despite advances, inappropriate analgesic treatment for burn patients is still seen. The objective of this review was to collect data on pain management in burn patients.

CONTENT

We reviewed the mechanisms of pain, burn patient assessment, as well as pharmacological and non-pharmacological treatment.

CONCLUSION

Pain management in burn patients is still a challenge for the multidisciplinary team. Frequent and continuous evaluation of the patient's response is very important due to the various stages that the hospitalized burn patient goes through, as well as a combination therapy with analgesic and non-pharmacological measures. Understanding the complexity of the pathophysiological, psychological, and biochemical changes a burn patient presents is the first step to achieve success in analgesic management.

Neuropathic mechanisms in the pathophysiology of burns pruritus: redefining directions for therapy and research

Pruritus in burn wounds is a common symptom affecting patient rehabilitation. Over the last decades, there has been a resurgence of interest into more effective strategies to combat this distressing problem; nevertheless, no reports exist in the literature to propose pathophysiological mechanisms responsible for the generation and persistence of pruritic symptoms in the late phases of burns rehabilitation. Neuronal pathways mediating pruritic and painful stimuli share striking similarities, which allows the comparative exploration of the less extensively studied pruritic mechanisms using pain models. Furthermore, emerging anatomical, neurophysiological, and pharmacological evidence supports the involvement of neuropathic mechanisms in chronic burns pruritus. This work updates the conceptual framework for the pathophysiology of burns itch by embracing the contribution of the central nervous system in the maintenance of symptoms into a chronic state. The proposed pathophysiological model paves new avenues in burns pruritus research and is likely to have implications in the quest for more effective therapeutic regimens in clinical practice.

Pediatric burn injuries

Pediatric burns comprise a major mechanism of injury, affecting millions of children worldwide, with causes including scald injury, fire injury, and child abuse. Burn injuries tend to be classified based on the total body surface area involved and the depth of injury. Large burn injuries have multisystemic manifestations, including injuries to all major organ systems, requiring close supportive and therapeutic measures. Management of burn injuries requires intensive medical therapy for multi-organ dysfunction/failure, and aggressive surgical therapy to prevent sepsis and secondary complications. In addition, pain management throughout this period is vital. Specialized burn centers, which care for these patients with multidisciplinary teams, may be the best places to treat children with major thermal injuries. This review highlights the major components of burn care, stressing the pathophysiologic consequences of burn injury, circulatory and respiratory care, surgical management, and pain management of these often critically ill patients.

Effect of gabapentin on morphine consumption and pain after surgical debridement of burn wounds: a double-blind randomized clinical trial study

Background:

Burn pain is recognized as being maximal during therapeutic procedures, and wound debridement can be more painful than the burn injury itself. Uncontrolled acute burn pain increases the stress response and the incidence of chronic pain and associated depression. Although opiates are excellent analgesics, they do not effectively prevent central sensitization to pain. The anticonvulsant gabapentin has been proven effective for treating neuropathic pain in large placebo-controlled clinical trials. Experimental and clinical studies have demonstrated antihyperalgesic effects in models with central neuronal sensitization. It has been suggested that central neuronal sensitization may play an important role in postoperative pain.

Objectives:

The aim of this study was to investigate the effect of gabapentin on morphine consumption and postoperative pain in burn patients undergoing resection of burn wounds.

Patients and Methods:

In a randomized, double-blind, placebo-controlled study, 50 burn patients received a single oral dose of gabapentin (1200mg) or placebo 2h before surgery. Anesthesia was induced with propofol and fentanyl and maintained by infusingpropofol, remifentanil, and 50% N2O in O2. All patients received patient-controlled analgesia with morphine at doses of 2.5 mg bolus and a lock-out time of 10 min for 24h before the operation. Pain was assessed on a visual analog scale (VAS) at rest and during movement at 1,4,8,12,16,20, and 24 h before the operation. Heart rate, oxygen saturation, mean arterial blood pressure, respiratory rate, sedation score, and morphine consumption were studied.

Results:

All the enrolled patients were able to complete the study; therefore, data from 50 patients wereanalyzed. The VAS scores at rest andduring movement at 1,4,8,12,16,20, and 24 h after the operation were significantly lower in the gabapentin group than in the placebo group (P < 0.05). Morphine consumption was significantly lessr in the gabapentin group than in the placebo group (P < 0.05). Sedation scores were similar in the 2 groups at all measured times. There were no differences in adverse effects between the groups.

Conclusions:

A single oral dose of 1200mg gabapentin resulted in a substantial reduction in postoperative morphine consumption and pain scores after surgical debridement in burn patients.

Analgesia and Sedation in the Intensive Care of Burn Patients

Objective: A variety of agents and techniques are employed in different countries, settings, and medical specialities in order to provide analgesia and sedation in intensive care. Several national guidelines have been published in recent years regarding sedation and analgesia in a general intensive care patient population; however, to date no data exist for patients with burn injuries. The aim of the study was to evaluate analgesia and sedation practice in the intensive care of burn patients in Europe. Design: A postal survey was sent to 188 burn centers in Europe. The addresses were provided by the European Burn Association. The heads of the intensive care units were asked to fill in a structured questionnaire concerning the use of analgesia and sedation in their units. Results: The overall response rate was 27.04%; 63% of European burn centers reported standard operating procedures for sedation and analgesia. A regular score-based assessment of sedation, analgesia, and delirium is carried out by 58%, 60%, and 5%, respectively, of the units. Propofol is the sedative most frequently used for short-term sedation and the weaning phase, whereas benzodiazepines are the preferred substances for medium- and long-term sedation. α2-agonists are widely used during weaning. Opioids are the analgesics of choice for approximately two thirds of the patients. Ketamine is preferred for analgesia in 12% and for sedation in 13% of all substances used. For painful procedures (eg, dressing changes), a large variety of different combinations of analgesics and sedatives are used. Half of the responding intensive care units use neuromuscular blocking agents and supportive nonpharmacological techniques. Two thirds of the European burn centers perceive the need for change in their concepts of analgesia and sedation. Conclusion: A wide variety of drugs are used for analgesia and sedation in European burn centers. This would appear to be due to lack of guidelines or scientific evidence. The implementation of regular assessment of sedation, analgesia, and delirium must be improved. The widespread use of neuromuscular blocking agents should be restricted or even abandoned. Two thirds of the units identify a need for change in their concepts. Valid scientific data are needed to develop guidelines for sedation and analgesia of burn patients.

Review of therapeutic agents for burns pruritus and protocols for management in adult and paediatric patients using the GRADE classification

To review the current evidence on therapeutic agents for burns pruritus and use the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) classification to propose therapeutic protocols for adult and paediatric patients. All published interventions for burns pruritus were analysed by a multidisciplinary panel of burns specialists following the GRADE classification to rate individual agents. Following the collation of results and panel discussion, consensus protocols are presented. Twenty-three studies appraising therapeutic agents in the burns literature were identified. The majority of these studies (16 out of 23) are of an observational nature, making an evidence-based approach to defining optimal therapy not feasible. Our multidisciplinary approach employing the GRADE classification recommends the use of antihistamines (cetirizine and cimetidine) and gabapentin as the first-line pharmacological agents for both adult and paediatric patients. Ondansetron and loratadine are the second-line medications in our protocols. We additionally recommend a variety of non-pharmacological adjuncts for the perusal of clinicians in order to maximise symptomatic relief in patients troubled with postburn itch. Most studies in the subject area lack sufficient statistical power to dictate a 'gold standard' treatment agent for burns itch. We encourage clinicians to employ the GRADE system in order to delineate the most appropriate therapeutic approach for burns pruritus until further research elucidates the most efficacious interventions. This widely adopted classification empowers burns clinicians to tailor therapeutic regimens according to current evidence, patient values, risks and resource considerations in different medical environments.

Gabapentin improves cold-pressor pain responses in methadone-maintained patients

Individuals on methadone maintenance for the treatment of addiction (MM) are demonstrated to be hyperalgesic to cold-pressor pain in comparison to matched controls and ex-opioid addicts, a finding described as clinical evidence of opioid-induced hyperalgesia (OIH). Interestingly, opioids induce hyperalgesia via many of the same neuro-inflammatory and central sensitization processes that occur with the development of neuropathic pain. Evaluated in this study was the efficacy of a key pharmacotherapy for neuropathic pain, gabapentin (GPN), to reverse OIH in MM patients. Utilizing a clinical trial design and double blind conditions, changes in cold-pressor pain threshold and tolerance following a 5-week trial of GPN (titrated to 2400mg/day) were evaluated at peak and trough methadone plasma levels in a well-characterized MM sample. Drug abstinence was encouraged via an escalating payment schedule, and compliance monitored via pill counts and GPN plasma levels; entered into the analyses were only those subjects compliant and abstinent throughout the study (approximately 45%). Utilizing change scores from baseline, significant improvements in cold-pressor pain threshold and pain tolerance were observed at both peak and trough methadone levels (p<0.05). Notably, drop-out rates due to medication side effects were low (2%) and the medication was well-tolerated. These results support that GPN, as prescribed for the treatment of neuropathic pain, is effective in decreasing OIH in patients who are abstinent and stable in methadone treatment.

Evidence and consensus-based German guidelines for the management of analgesia, sedation and delirium in intensive care--short version

Targeted monitoring of analgesia, sedation and delirium, as well as their appropriate management in critically ill patients is a standard of care in intensive care medicine. With the undisputed advantages of goal-oriented therapy established, there was a need to develop our own guidelines on analgesia and sedation in intensive care in Germany and these were published as 2(nd) Generation Guidelines in 2005. Through the dissemination of these guidelines in 2006, use of monitoring was shown to have improved from 8 to 51% and the use of protocol-based approaches increased to 46% (from 21%). Between 2006-2009, the existing guidelines from the DGAI (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin) and DIVI (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin) were developed into 3(rd) Generation Guidelines for the securing and optimization of quality of analgesia, sedation and delirium management in the intensive care unit (ICU). In collaboration with another 10 professional societies, the literature has been reviewed using the criteria of the Oxford Center of Evidence Based Medicine. Using data from 671 reference works, text, diagrams and recommendations were drawn up. In the recommendations, Grade "A" (very strong recommendation), Grade "B" (strong recommendation) and Grade "0" (open recommendation) were agreed. As a result of this process we now have an interdisciplinary and consensus-based set of 3(rd) Generation Guidelines that take into account all critically illness patient populations. The use of protocols for analgesia, sedation and treatment of delirium are repeatedly demonstrated. These guidelines offer treatment recommendations for the ICU team. The implementation of scores and protocols into routine ICU practice is necessary for their success.