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

The scar-reducing effect of a novel chitosan gel: an in vivo study

OBJECTIVE

Scar tissue formation, as a normal part of wound healing, initiates in the proliferation phase, continues after the remodelling phase, and may cause an unpleasant appearance or disruption in normal functioning. This study investigated the effects of a topical gel on acute wound healing and reducing scars in a rat model.

METHOD

ChitoScar (ChitoTech Company, Iran), a commercial scar-reducing gel based on chitosan, was analysed for antibacterial and antiviral activity through a quantitative suspension test. Its cytotoxic effect was investigated, and then irritation and delayed-type hypersensitivity tests were carried out on rabbits through direct application of the gel. Furthermore, the effect of the chitosan-based gel on wound healing and scar tissue formation was studied in rats with an acute wound in two groups: the treatment group (topical application of the chitosan-based gel); and the control group (without treatment). Histopathological examination was carried out based on the inflammatory cells, collagen fibre, keratinocytes and fibroblasts.

RESULTS

Analysis revealed that the chitosan-based gel had no cytotoxicity and caused no erythema, oedema, local or other systemic adverse response. Wound healing occurred earlier in the treatment group, which was a result of a significant increase in re-epithelialisation, angiogenesis, fibroblast population and collagen fibre thickness (p<0.05). In the treatment group, wounds healed completely after 21 days and scars totally disappeared after 28 days, while in the control group, wound healing remained incomplete with distinct scar tissue.

CONCLUSION

The results demonstrated the positive effect of the chitosan-based gel on the duration and quality of the wound healing process, as well as minimising the scar tissue formation in this in vivo study.

Identifying Stress-Exacerbated Thermal-Injury Induced MicroRNAs

Using a model of combat and operational stress reaction (COSR), our lab recently showed that exposure to an unpredictable combat stress (UPCS) procedure prior to a thermal injury increases pain sensitivity in male rats. Additionally, our lab has recently shown that circulating extracellular vesicle-microRNAs (EV-miRNAs), which normally function to suppress inflammation, were downregulated in a male rat model of neuropathic pain. In this current study, male and female rats exposed to UPCS, followed by thermal injury, were evaluated for changes in circulating EV-miRNAs. Adult female and male Sprague Dawley rats were exposed to a UPCS procedure for either 2 or 4 weeks. Groups consisted of the following: nonstress (NS), stress (S), NS + thermal injury (TI), and S + TI. Mechanical sensitivity was measured, and plasma was collected at baseline, throughout the UPCS exposure, and post-thermal injury. EV-miRNA isolation was performed, followed by small RNA sequencing and subsequent data analysis. UPCS exposure alone resulted in mechanical allodynia in both male and female rats at specific time points. Thermal-injury induction occurring at peak UPCS resulted in increased mechanical allodynia in the injured hind paw compared to thermal injury alone. Differential expression of the EV-miRNAs was observed between the NS and S groups as well as between NS + TI and S + TI groups. Consistent differences in EV-miRNAs are detectable in both COSR as well as during the development of mechanical sensitivity and potentially serve as key regulators, biomarkers, and targets in the treatment of COSR and thermal-injury induced mechanical sensitivity. PERSPECTIVE: This article presents the effects of unpredictable combat stress and thermal injury on EV-contained microRNAs in an animal model. These same mechanisms may exist in clinical patients and could be future prognostic and diagnostic biomarkers.

An Overview of Recent Developments in the Management of Burn Injuries

According to the World Health Organization (WHO), around 11 million people suffer from burns every year, and 180,000 die from them. A burn is a condition in which heat, chemical substances, an electrical current or other factors cause tissue damage. Burns mainly affect the skin, but can also affect deeper tissues such as bones or muscles. When burned, the skin loses its main functions, such as protection from the external environment, pathogens, evaporation and heat loss. Depending on the stage of the burn, the patient's condition and the cause of the burn, we need to choose the most appropriate treatment. Personalization and multidisciplinary collaboration are key to the successful management of burn patients. In this comprehensive review, we have collected and discussed the available treatment options, focusing on recent advances in topical treatments, wound cleansing, dressings, skin grafting, nutrition, pain and scar tissue management.

A comparison of interactive immersive virtual reality and still nature pictures as distraction-based analgesia in burn wound care

PURPOSE

Non-pharmacologic adjuncts to opioid analgesics for burn wound debridement enhance safety and cost effectiveness in care. The current study explored the feasibility of using a custom portable water-friendly immersive VR hardware during burn debridement in adults, and tested whether interactive VR would reduce pain more effectively than nature stimuli viewed in the same VR goggles.

METHODS

Forty-eight patients with severe burn injuries (44 adults and 4 children) had their burn injuries debrided and dressed in a wet wound care environment on Study Day 1, and 13 also participated in Study Day 2.

INTERVENTION

The study used a within-subject design to test two hypotheses (one hypothesis per study day) with the condition order randomized. On Study Day 1, each individual (n = 44 participants) spent 5 min of wound care in an interactive immersive VR environment designed for burn care, and 5 min looking at still nature photos and sounds of nature in the same VR goggles. On Study Day 2 (n = 12 adult participants and one adolescent from Day 1), each participant spent 5 min of burn wound care with no distraction and 5 min of wound care in VR, using a new water-friendly VR system. On both days, during a post-wound care assessment, participants rated and compared the pain they had experienced in each condition. OUTCOME MEASURES ON STUDY DAYS 1 AND 2: Worst pain during burn wound care was the primary dependent variable. Secondary measures were ratings of time spent thinking about pain during wound care, pain unpleasantness, and positive affect during wound care.

RESULTS

On Study Day 1, no significant differences in worst pain ratings during wound care were found between the computer-generated world (Mean = 71.06, SD = 26.86) vs. Nature pictures conditions (Mean = 68.19, SD = 29.26; t < 1, NS). On secondary measures, positive affect (fun) was higher, and realism was lower during computer-generated VR. No significant differences in pain unpleasantness or "presence in VR" between the two conditions were found, however. VR VS. NO VR. (STUDY DAY 2): Participants reported significantly less worst pain when distracted with adjunctive computer generated VR than during standard wound care without distraction (Mean = 54.23, SD = 26.13 vs 63.85, SD = 31.50, t(11) = 1.91, p < .05, SD = 17.38). In addition, on Study Day 2, "time spent thinking about pain during wound care" was significantly less during the VR condition, and positive affect was significantly greater during VR, compared to the No VR condition.

CONCLUSION

The current study is innovative in that it is the first to show the feasibility of using a custom portable water-friendly immersive VR hardware during burn debridement in adults. However, contrary to predictions, interactive VR did not reduce pain more effectively than nature stimuli viewed in the same VR goggles.

Spinal microglia-derived TNF promotes the astrocytic JNK/CXCL1 pathway activation in a mouse model of burn pain

Burn injury-induced pain (BIP) is an extremely complicated condition usually resistant to analgesic drugs, while its pathogenesis remains unknown. Considerable attention has been attracted to elucidate the glial mechanisms in chronic pain. In this study, we initiatively used a mouse model of second-degree BIP to investigate the underlying non-neuronal mechanisms at the spinal cord level. Our behavioral results showed that hind-paw burn injury caused persistent allodynia and hyperalgesia for 2 weeks in mice. Further studies revealed that both microglia and astrocytes activated in a spatially- and temporally-dependent manner in spinal cord after burn injury. In addition, the phosphorylated p38 mitogen-activated protein kinase (MAPK)-mediated tumor necrosis factor (TNF) release in spinal microglia is essentially attributed to the early stage of BIP, while the c-Jun N-terminal kinase (JNK) MAPK-dependent chemokine CXCL1 expression is mainly involved in the maintenance of pain hypersensitivity. Most strikingly, burn injury-induced pain symptoms and the activation of astrocytes were significantly suppressed by TNF inhibitor Thalidomide. On the contrary, intrathecal injection of TNF caused apparent pain hypersensitivity, accompanied by the activation of astrocytes and the upregulation of CXCL1 via the JNK MAPK signaling pathway, indicating that TNF is the key cytokine in the interaction between microglia and astrocytes at the spinal level. Moreover, treatment with the CXCR2 receptor antagonist SB225002 to block the biological activities of CXCL1 significantly attenuated the mechanical allodynia and thermal hyperalgesia in this BIP model. Taken together, this study indicates that intervention of glial pathways provides a new perspective in the management of BIP.

Interacting with virtual objects via embodied avatar hands reduces pain intensity and diverts attention

The current study introduces a new paradigm for exploring cognitive factors in pain. Interacting with virtual objects via embodied avatar hands increased the illusion of “being there” in the virtual world, increased VR analgesia for acute pain, and reduced accuracy on an attention demanding task. Twenty-four healthy volunteer college students participated in this within-subject randomized crossover design study. During Phase 1, each participant received brief thermal pain stimuli during interactive embodied avatar VR vs. passive VR (no avatar and no interactivity), VR treatment order randomized. After each pain stimulus, participants provided subjective 0–10 ratings of pain. Compared to the passive VR condition, during the interactive avatar VR, participants reported significant reductions in (1) worst pain, (2) pain unpleasantness, (3) time thinking about pain and (4). they had significantly more fun during the pain stimulus (p = .000 for each). During Phase 2, participants performed a divided attention task in each of the two VR conditions. Participants made significantly more errors on the divided attention task during the interactive avatar VR condition, compared to passive VR, implicating an attention mechanism for how virtual reality reduces pain and helping understand how VR influences pain perception.

Trial registration: NCT04245475. Date of registration: 29/01/2020.

Evaluating the utility of a CO2 surgical laser for piglet castration to reduce pain and improve wound healing: a pilot study

CO₂ surgical lasers are widely used for procedures in veterinary and human medicine. There is evidence to suggest surgery using a CO₂ laser reduces pain and swelling and improves healing time compared with surgery with a scalpel. Millions of piglets in North America are surgically castrated each year using a scalpel. Therefore, piglet welfare may be improved by making refinements to the surgical procedure. The objectives of this preliminary study were to determine the ability of a CO₂ surgical laser to (1) reduce pain and (2) improve wound healing of piglets undergoing surgical castration. Two-day-old male Yorkshire × Landrace piglets were used and randomly assigned to 1 of 3 treatments (n = 10 piglets/treatment group): surgical castration with the CO₂ laser, surgical castration with a scalpel, or sham (uncastrated control). Piglets were video recorded in their pens for 1 hr preprocedure and from 0 to 2, 6 to 8, and at 24 hr postprocedure for behavior scoring. Surgical site images were collected at baseline, 0, 8, 24, 48, 72, 96, 120, 144, and 168 hr postcastration for wound healing assessment. Infrared thermography images of the surgical site were also taken at baseline, 0, 0.5, 8, and 24 hr postprocedure to assess inflammation. Finally, blood was collected from each piglet at baseline and 0.5 hr postcastration to assess cortisol levels, prostaglandin E metabolite and pig-major acute phase protein concentration. Laser-castrated piglets displayed more pain behaviors across the observation period than scalpel-castrated piglets (P = 0.05). Laser-castrated piglets also displayed significantly more agonistic behavior than both scalpel-castrated piglets (P = 0.005) and sham piglets (P = 0.036); yet, laser-castrated piglets had significantly lower temperatures at the site of incision compared with scalpel-castrated piglets (P = 0.0211). There was no significant difference in wound healing or any of the blood parameters assessed between laser-castrated and scalpel-castrated piglets. There was evidence of thermal tissue damage on the scrotum of piglets that were castrated using the CO₂ laser. This may have resulted in the unremarkable healing time and the increased pain behavior observed in this study. The surgical laser technique should be refined before conclusions can be made regarding the utility of a CO₂ laser for piglet castration.

Butorphanol in combination with dexmedetomidine provides efficient pain management in adult burn patients

OBJECTIVE

This study aimed to compare the sedation and analgesic effects of butorphanol alone and butorphanol in combination with dexmedetomidine on dressing changes in adult burn patients.

METHOD

From June 2016 to May 2019, 44 adult burn patients from our department were enrolled in this prospective, double-blinded study. Their total burn surface area (TBSA) varied from 10% to 30%; and the depth of burn injury ranged from second degree to third degree. The patients were randomized into two groups. In the control group, butorphanol combined with saline was injected into the body via venous route during dressing change. In the observation group, butorphanol in combination with dexmedetomidine was injected. The variation in mean blood pressure, heart rate, respiratory rate, and peripheral oxygen saturation were recorded at various time-points of the procedure. Visual Analogue Scale (VAS) of pain and Ramsay Sedation Scores (RSS) were also recorded at different time points. Consumption of butorphanol and adverse events in these two groups were compared.

RESULTS

The mean blood pressure and heart rate were significantly decreased in the observation group before butorphanol injection (P < 0.05) and before the dressing change (P < 0.05). The respiratory rates and peripheral oxygen saturation of these two groups showed no significant differences at all time points (P > 0.05). Patients in the observation group had lower VAS scores during dressing change (P < 0.05). The RSS Scores in the observation group were higher than those in the control group during (P < 0.05) and after the dressing change (P < 0.05). The consumption of butorphanol was more in the control group (P < 0.05), and the adverse events recorded in the control group were higher (P < 0.05).

CONCLUSION

Butorphanol combined with dexmedetomidine can reduce analgesic use of butorphanol during dressing change. This combination resulted in a higher sedation score and fewer adverse effects.

Virtual Reality Analgesia for Children With Large Severe Burn Wounds During Burn Wound Debridement

The objective of this study was to compare the effect of adjunctive virtual reality vs. standard analgesic pain medications during burn wound cleaning/debridement. Participants were predominantly Hispanic children aged 6-17 years of age, with large severe burn injuries (TBSA = 44%) reporting moderate or higher baseline pain during burn wound care. Using a randomized between-groups design, participants were randomly assigned to one of two groups, (a) the Control Group = pain medications only or (b) the VR Group = pain medications + virtual reality. A total of 50 children (88% Hispanic) with large severe burns (mean TBSA > 10%) received severe burn wound cleaning sessions. For the primary outcome measure of worst pain (intensity) on Study Day 1, using a between groups ANOVA, burn injured children in the group that received virtual reality during wound care showed significantly less pain intensity than the No VR control group, [mean worst pain ratings for the No VR group = 7.46 (SD = 2.93) vs. 5.54 (SD = 3.56), F (1,48) = 4.29, <0.05, MSE = 46.00]. Similarly, one of the secondary pain measures, "lowest pain during wound care" was significantly lower in the VR group, No VR = 4.29 (SD = 3.75) vs. 1.68 (2.04) for the VR group, F(147) = 9.29, < 0.005, MSE = 83.52 for Study Day 1. The other secondary pain measures showed the predicted pattern on Study Day 1, but were non-significant. Regarding whether VR reduced pain beyond Study Day 1, absolute change in pain intensity (analgesia = baseline pain minus the mean of the worst pain scores on Study days 1-10) was significantly greater for the VR group, F (148) = 4.88, p < 0.05, MSE = 34.26, partial eta squared = 0.09, but contrary to predictions, absolute change scores were non-significant for all secondary measures.

Copaiba oleoresin has topical antinociceptive activity in a UVB radiation-induced skin-burn model in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Copaiba oleoresin, extracted from Copaifera L., is used as a wound healing, analgesic, antimicrobial and, mainly, anti-inflammatory agent. Thus, in this study we investigated the antinociceptive and anti-inflammatory effects of a topical formulation containing Copaiba oleoresin (3%) in a UVB radiation-induced skin burn model (0.75 J/cm²) in mice and performed a cream-formulation stability study.

MATERIALS AND METHODS

The chemical composition of Copaiba oleoresin was analyzed using gas chromatography (GC-MS). The topical antinociceptive (evaluated through mechanical allodynia and thermal hyperalgesia) and the anti-inflammatory (dermal thickness and inflammatory cell infiltration) effects of treatments were assessed. The cream-formulation stability study was performed after two months, and organoleptic characteristics, pH, spreadability and rheological characteristics were analyzed.

RESULTS

Copaiba oleoresin cream was able to prevent UVB radiation-induced mechanical allodynia on the 2nd, 3rd and 4th day after UVB radiation exposure with a maximum inhibition (I_max) of 64.6 ± 7% observed on the 2nd day; it also reduced the thermal hyperalgesia on the 1st and 2nd days post UVB radiation, with a I_max of 100% observed on the 2nd day. Moreover, topical treatment with Copaiba oleoresin cream inhibited the inflammatory cell infiltration, but did not reduce the dermal thickness. Such effects can be attributed, at least in part, to the presence of biological components, such as β-caryophyllene and other sesquiterpenes identified by GC-MS.

CONCLUSION

Our results demonstrate that the topical formulation containing Copaiba oleoresin presented antinociceptive and anti-inflammatory effects in mice subjected to a UVB radiation and that the cream-formulation was stable for two months. Thus, use of Copaiba oleoresin is a promising strategy for the treatment of inflammatory pain associated with sunburn.

Virtual Reality Analgesia With Interactive Eye Tracking During Brief Thermal Pain Stimuli: A Randomized Controlled Trial (Crossover Design)

In light of growing concerns about opioid analgesics, developing new non-pharmacologic pain control techniques has become a high priority. Adjunctive virtual reality can help reduce acute pain during painful medical procedures. However, for some especially painful medical procedures such as burn wound cleaning, clinical researchers recommend that more distracting versions of virtual reality are needed, to further amplify the potency of virtual reality analgesia. The current study with healthy volunteers explores for the first time whether interacting with virtual objects in Virtual Reality (VR) via "hands free" eye-tracking technology integrated into the VR helmet makes VR more effective/powerful than non-interactive/passive VR (no eye-tracking) for reducing pain during brief thermal pain stimuli.

METHOD

Forty eight healthy volunteers participated in the main study. Using a within-subject design, each participant received one brief thermal pain stimulus during interactive eye tracked virtual reality, and each participant received another thermal pain stimulus during non-interactive VR (treatment order randomized). After each pain stimulus, participants provided subjective 0-10 ratings of cognitive, sensory and affective components of pain, and rated the amount of fun they had during the pain stimulus.

RESULTS

As predicted, interactive eye tracking increased the analgesic effectiveness of immersive virtual reality. Compared to the passive non-interactive VR condition, during the interactive eye tracked VR condition, participants reported significant reductions in worst pain (p < 0.001) and pain unpleasantness (p < 0.001). Participants reported a significantly stronger illusion of presence (p < 0.001), and significantly more fun in VR (p < 0.001) during the interactive condition compared to during passive VR. In summary, as predicted by our primary hypothesis, in the current laboratory acute pain analog study with healthy volunteers, increasing the immersiveness of the VR system via interactive eye tracking significantly increased how effectively VR reduced worst pain during a brief thermal pain stimulus. Although attention was not directly measured, the pattern of pain ratings, presence ratings, and fun ratings are consistent with an attentional mechanism for how VR reduces pain. Whether the current results generalize to clinical patient populations is another important topic for future research. Additional research and development is recommended.

Drug-specific differences in the ability of opioids to manage burn pain

Burn injury pain is a significant public health problem. Burn injury treatment has improved tremendously in recent decades. However, an unintended consequence is that a larger number of patients now survive more severe injuries, and face intense pain that is very hard to treat. Although many efforts have been made to find alternative treatments, opioids remain the most effective medication available. Burn patients are frequently prescribed opioids in doses and durations that are significantly higher and longer than standard analgesic dosing guidelines. Despite this, many continue to experience unrelieved pain. They are also placed at a higher risk for developing dependence and opioid use disorder. Burn injury profoundly alters the functional state of the immune system. It also alters the expression levels of receptor, effector, and signaling molecules within the spinal cord's dorsal horn. These alterations could explain the reduced potency of opioids. However, recent studies demonstrate that different opioids signal preferentially via differential signaling pathways. This ligand-specific signaling by different opioids implies that burn injury may reduce the antinociceptive potency of opioids to different degrees, in a drug-specific manner. Indeed, recent findings hint at drug-specific differences in the ability of opioids to manage burn pain early after injury, as well as differences in their ability to prevent or treat the development of chronic and neuropathic pain. Here we review the current state of opioid treatment, as well as new findings that could potentially lead to opioid-based pain management strategies that may be significantly more effective than the current solutions.

Sensitivity and wound healing after hot-iron disbudding in goat kids

Hot-iron disbudding in goat kids causes acute pain and tissue damage. However, the duration of healing and wound sensitivity is unknown. We assessed wound healing and pain sensitivity in 18 female dairy goat kids disbudded with a heated iron at 10 d of age (range: 5-15 d). Pressure algometry was carried out twice a week from d 1 after disbudding to determine the mechanical nociceptive threshold (MNT) in 4 locations on each bud (front, lateral, caudal, and middle). At the same time, digital and infrared images of the wounds were used to visually and thermally describe the healing process. Wounds were visually scored daily for the presence of 7 tissue types: attached necrotic tissue, detached necrotic tissue, burns outside the necrotic ring, exudate, granulation, crust, and epithelium. All data were taken until epithelium was present for 4 consecutive days. Necrotic tissue detached completely from the scalp 26 ± 5 d after the procedure (mean ± SD; range: 17-43 d), and wounds took 50 ± 8 d (35-63 d) to re-epithelialize. Wounds were more sensitive at all stages of the healing process compared with re-epithelialized tissue. The caudal and middle locations were the most- and least-sensitive test sites (1.24 ± 0.10 and 1.90 ± 0.10 N, respectively; mean ± SE). Goats became less responsive to stimulation as their wounds decreased in size. Sensitivity did not differ between left and right sides of the head. Maximum surface temperature of necrotic tissue, when present, tended to be higher than that of epithelium (38.8 ± 0.2 vs. 38.1 ± 0.2°C); temperature did not differ among other tissue types. Our results indicate that hot-iron disbudding wounds in goats take, on average 7, wk to re-epithelialize (35-63 d) and are painful throughout this time, raising additional welfare concerns about this procedure.

Immersive Virtual Reality as an Adjunctive Non-opioid Analgesic for Pre-dominantly Latin American Children With Large Severe Burn Wounds During Burn Wound Cleaning in the Intensive Care Unit: A Pilot Study

Background/Aim: Using a within-subjects, within-wound care design, this pilot study tested for the first time, whether immersive virtual reality (VR) can serve as an adjunctive non-opioid analgesic for children with large severe burn wounds during burn wound cleaning in the ICU, in a regional burn center in the United States, between 2014–2016.

Methods: Participants included 48 children from 6 years old to 17 years of age with >10% TBSA burn injuries reporting moderate or higher worst pain during no VR on Day 1. Forty-four of the 48 children were from developing Latin American countries. Patients played adjunctive SnowWorld, an interactive 3D snowy canyon in virtual reality during some portions of wound care, vs. No VR during comparable portions of the same wound care session (initial treatment condition randomized). Using Graphic Rating scales, children's worst pain ratings during “No VR” (treatment as usual pain medications) vs. their worst pain during “Yes VR” was measured during at least 1 day of wound care, and was measured for up to 10 study days the patient used VR.

Results: VR significantly reduced children's “worst pain” ratings during burn wound cleaning procedures in the ICU on Day 1. Worst pain during No VR = 8.52 (SD = 1.75) vs. during Yes VR = 5.10 (SD = 3.27), t₍₄₇₎ = 7.11, p < 0.001, SD = 3.33, CI = 2.45–4.38, Cohen's d = 1.03 (indicating large effect size). Patients continued to report the predicted pattern of lower pain and more fun during VR, during multiple sessions.

Conclusion: Immersive virtual reality can help reduce the pain of children with large severe burn wounds during burn wound cleaning in the Intensive Care Unit. Additional research and development is recommended.

Involvement of brain-derived neurotrophic factor (BDNF) in chronic intermittent stress-induced enhanced mechanical allodynia in a rat model of burn pain

BACKGROUND

Reports show that stressful events before injury exacerbates post-injury pain. The mechanism underlying stress-induced heightened thermal pain is unclear. Here, we examined the effects of chronic intermittent stress (CIS) on nociceptive behaviors and brain-derived nerve growth factor (BDNF) system in the prefrontal cortex (PFC) and hypothalamus of rats with and without thermal injury.

RESULTS

Unstressed rats showed transient mechanical allodynia during stress exposure. Stressed rats with thermal injury displayed persistent exacerbated mechanical allodynia (P < 0.001). Increased expression of BDNF mRNA in the PFC (P < 0.05), and elevated TrkB and p-TrkB (P < 0.05) protein levels in the hypothalamus were observed in stressed rats with thermal injury but not in stressed or thermally injured rats alone. Furthermore, administration of CTX-B significantly reduced stress-induced exacerbated mechanical allodynia in thermally injured rats (P < 0.001).

CONCLUSION

These results indicate that BDNF-TrkB signaling in PFC and hypothalamus contributes to CIS-induced exacerbated mechanical allodynia in thermal injury state.

Evaluation of propylene glycol nanoliposomes containing curcumin on burn wound model in rat: biocompatibility, wound healing, and anti-bacterial effects

Curcumin is an effective wound healing agent in burn therapy, but due to its low bioavailability, it is required to be formulated for topical therapy. Liposomal nanocarriers are developed as stable and efficient dermal delivery systems. In this study, we prepared curcumin-propylene glycol liposomes (Cur-PgL) to treat animals subjected to second degree burns. The characterization tests confirmed the production of monodisperse nanoliposomes of average size of about 145 nm with high entrapment efficiency percentage and a sustained release behavior. TEM analysis of nanocarriers showed no aggregation in long time storage up to 60 days. The biocompatibility of the Cur-PgL formulation was evaluated by ISO standards. We found that Cur-PgL 0.3% was the effective dose in injured rats without any side effects on intact skin. The cytotoxicity of the Cur-PgL 0.3% nanovesicles was also assessed on human dermal fibroblast (HDF) cells. The results showed no detectable cytotoxicity, but considerable cytotoxicity was observed in higher concentration of 1.5 and 3 mg/ml of free and PgL forms of curcumin. Eight days of application of Cur-PgL on burned rats resulted in a significant (P<0.001) recovery of wound repair parameters, and after 18 days, wound contraction occurred significantly (P < 0.001) compared to the other groups. The antibacterial activity of the Cur-PgL formulation was found to be similar to the silver sulfadiazine (SSD) cream 1% regarding the inhibition of the bacterial growth. In conclusion, the low dose of curcumin nanoliposomal formulation efficiently improved injuries and infections of burn wounds and it can be considered in burn therapy.

MRI compatibility of silver based wound dressings

As silver dressings gain more widespread use, it is more likely that patients with silver-based dressings will also undergo magnetic resonance imaging (MRI). In current practice, these dressings are removed prior to imaging due to concerns over heating and image distortion. As dressing changes can be painful, the need to remove dressings simply for MRI may increase pain and contribute to opioid dependency. To examine the need for dressing removal, American Society for Testing and Materials International standards for assessing device deflection and torque were performed on 5 silver containing and 3 non-silver control dressings. Magnetically induced heating and image distortion were examined in a porcine hind limb wound dressed with control and test dressings. The limb was scanned in a clinical high field 3T MRI scanner using a series of standard MRI sequences (Survey, T₁-weighted SE, T₁-weighted IR TSE, T₂-weighted TSE, DUAL TSE, and FLAIR). Deflection and torsion were not detected in control or silver-based dressings. For all combinations of dressings and MRI scans, average heating was between 0-0.2°C. Additionally, dressings, in dry and hydrated forms, caused no image distortion in any MRI scan performed. Evaluation of MRI safety and compatibility revealed no concerns for safety or image distortion in any of the silver-containing wound dressings tested thus it would be acceptable to leave these dressings intact during MRI. The ability to leave dressings in place during imaging will provide a significant benefit to patient care by reducing pain associated with dressing removal.

Efficacy and feasibility of opioids for burn analgesia: An evidence-based qualitative review of randomized controlled trials

Opioids are commonly used for burn analgesia, but no comprehensive reviews have been published on such use. We aimed to assess the literature regarding the effectiveness and side effects of opioids both in adult and pediatric burn patients. We conducted a systematic search of the PubMed, Embase, Cochrane, and Web of Science databases. Information on study characteristics, results, and interventions was extracted. The review identified nine studies that satisfied the inclusion criteria. Burn sizes of patients ranged from 1% to 62% of the body. The examined studies showed that dressing or cream containing morphine could potentially decrease pain, use of analgesics, and side effects associated with systemic opioid medications compared with control groups. Oral transmucosal fentanyl citrate (OTFC) was equivalent, or even preferable, to oral morphine, hydromorphone, and oxycodone in provision of analgesia for burn wound care in pediatric patients. Intranasal fentanyl (INF) was equivalent to oral morphine in burn wound care both in adult and pediatric patients. OTFC and INF could be considered as viable non-invasive analgesic alternatives to oral opioids for procedural burn pain. However, the level of evidence still seems quite uncertain because of the limited sample size.