Influence of local anaesthetics on inflammatory activity postburn

EMLA cream in burns: A systematic review of safety, analgesic efficacy, and effects on burn pathophysiology

AIM

Management of procedural pain in burn care is challenging. Lidocaine-prilocaine cream 5%, eutectic mixture of local anesthetics (EMLA®), is a widely used, effective local anesthetic cream approved for normal intact skin, genital mucosa for superficial surgical procedures, and debridement of chronic leg ulcers. This comprehensive review aimed to determine the safety, analgesic efficacy, and effects of EMLA on burn pathophysiology to provide evidence-based clinical recommendations for introducing the topical anesthetic into burn care.

METHODS

The PRISMA guidelines were followed for conducting a systematic PubMed search to include all relevant preclinical and clinical studies, according to pre-specified eligibility criteria.

RESULTS

Fifteen studies were included in a qualitative synthesis, among which nine were human and six were animal studies. To date, safety and pharmacokinetic data on EMLA application in burns have been limited. Nevertheless, human studies indicated that EMLA is safe and provides adequate procedural-pain relief in adults when applied to smaller burns. Caution should be exercised when using EMLA in younger children, as systemic toxicity, pertaining to prilocaine-induced methemoglobinemia, has been reported owing to overdosing (high doses applied over large burn areas). Furthermore, animal studies demonstrate the potential beneficial effects of EMLA on burn pathophysiology such as anti-inflammatory, decreased capillary permeability to plasma proteins and edema formation, and improved tissue perfusion, which are factors that may impact burn wound progression.

CONCLUSION

Current data on EMLA use in the management of procedural pain in small burns are sparse but suggest that EMLA is safe and effective in adults. Further clinical pharmacokinetic studies are warranted, especially for application on larger burn areas.

Effect of Intravenous Lidocaine on Inflammatory and Apoptotic Response of Ischemia-Reperfusion Injury in Pigs Undergoing Lung Resection Surgery

Background

Ischemia-reperfusion injury is one of the most critical phenomena in lung transplantation and causes primary graft failure. Its pathophysiology remains incompletely understood, although the inflammatory response and apoptosis play key roles. Lidocaine has anti-inflammatory properties. The aim of this research is to evaluate the effect of intravenous lidocaine on the inflammatory and apoptotic responses in lung ischemia-reperfusion injury.

Methods

We studied the histological and immunohistochemical changes in an experimental model of lung transplantation in pigs. Twelve pigs underwent left pneumonectomy, cranial lobectomy, caudal lobe reimplantation, and 60 minutes of graft reperfusion. Six of the pigs made up the control group, while six other pigs received 1.5 mg/kg of intravenous lidocaine after induction and a 1.5 mg/kg/h intravenous lidocaine infusion during surgery. In addition, six more pigs underwent simulated surgery. Lung biopsies were collected from the left caudal lobe 60 minutes after reperfusion. We conducted a double study on these biopsies and assessed the degree of inflammation, predominant cell type (monocyte-macrophage, lymphocytes, or polymorphous), the degree of congestion, and tissue edema by hematoxylin and eosin stain. We also conducted an immunohistochemical analysis with antibodies against CD68 antigens, monocyte chemoattractant protein-1 (MCP-1), Bcl-2, and caspase-9.

Results

The lungs subjected to ischemia-reperfusion injury exhibited a higher degree of inflammatory infiltration. The predominant cell type was monocyte-macrophage cells. Both findings were mitigated by intravenous lidocaine administration. Immunohistochemical detection of anti-CD68 and anti-MCP-1 showed higher infiltration in the lungs subjected to ischemia-reperfusion injury, while intravenous lidocaine decreased the expression. Ischemia-reperfusion induced apoptotic changes and decreased Bcl-2 expression. The group treated with lidocaine showed an increased number of Bcl-2-positive cells. No differences were observed in caspase-9 expression.

Conclusions

In our animal model, intravenous lidocaine was associated with an attenuation of the histological markers of lung damage in the early stages of reperfusion.

Epicardial Interventions: Impact of Liposomal Bupivacaine on Postprocedural Management (The EPI-LIBRE Study)

Background:

Electrophysiological procedures such as epicardial ventricular tachycardia ablation and Lariat left atrial appendage ligation that involve the epicardial space are typically associated with significant postoperative pain due to mechanical irritation and associated inflammation. There is an unmet need for an effective pain management strategy in this group of patients. We studied how this impacts patient comfort and duration of hospitalization and other associated comorbidities related to pericardial access.

Methods:

This is a multicenter retrospective study including 104 patients who underwent epicardial ventricular tachycardia ablation and Lariat left atrial appendage exclusion. We compared 53 patients who received postprocedural intrapericardial liposomal bupivacaine (LB)+oral colchicine (LB group) and 51 patients who received colchicine alone (non-LB group) between January 2015 and March 2018.

Results:

LB was associated with significant lowering of median pain scale at 6 hours (1.0 [0–2.0] versus 8.0 [6.0–8.0], P <0.001), 12 hours (1.0 [1.0–2.0] versus 6.0 [5.0–6.0], P <0.001), and up to 48 hours postprocedure. Incidence of acute severe pericarditis delayed pericardial effusion and gastrointestinal adverse effects were similar in both groups. Median length of stay was significantly lower in LB group (2.0 versus 3.0; adjusted linear coefficient −1 [CI −1.3 to −0.6], P <0.001). Subgroup analysis demonstrated similar favorable outcomes in both Lariat and epicardial ventricular tachycardia ablation groups.

Conclusions:

Addition of intrapericardial postprocedural LB to oral colchicine in patients undergoing epicardial access during ventricular tachycardia ablation or Lariat procedure is associated with significantly decreased numeric pain score up to 48 hours compared with colchicine alone. It is also associated with significantly shorter length of hospital stay without an increase in the risk of adverse events.

Acute cortisol and behavior of dairy goat kids administered local anesthesia, topical anesthesia or systemic analgesia prior to cautery disbudding

Cautery disbudding of goat kids causes thermal burns and tissue destruction, which results in acute and post-operative pain and negatively affects animal welfare. The objectives of this study were to evaluate acute cortisol concentrations and behavioral responses associated with (1) injecting a lidocaine ring block prior to cautery disbudding and comparing this to saline injections and (2) pain mitigation strategies (lidocaine ring block, topical eutectic mixture of local anesthetics (EMLA) cream, oral meloxicam) on cautery disbudded dairy goat kids. Sixty doe kids were allocated to one of six treatments: (1) disbudding without pain relief (DB), (2) a ring block using 1% lidocaine (DBLA) 20 min before disbudding, (3) saline injection (DBSA) 20 min before disbudding, (4) oral meloxicam 60 min before disbudding (DBMEL), (5) EMLA cream rubbed into the buds 60 min before disbudding (DBEM) and (6) handled but not disbudded (HAND). Blood was sampled pre- (-20 and -5 min) and post-treatment (15 and 30 min) to assess plasma cortisol concentrations and behavior during treatment was recorded using video cameras to assess rump movements, tail shakes and vocalizations (values presented as number/treatment). DBLA and DBSA kids showed elevated cortisol above baseline 5 min pre-disbudding (after injections) (P ≤ 0.01), which was no different to cortisol 15 min post-disbudding (P > 0.05). Rump movements and tail shakes of DBLA (5.5 ± 0.8 and 6.9 ± 1.2) and DBSA kids (5.6 ± 0.8 and 7.2 ± 1.2) were no different to those of DB kids (P > 0.10). Cortisol was elevated from baseline for 30 min post-disbudding for DBEM kids and DBMEL kids (P ≤ 0.05). Rump movements, tail shakes and vocalizations of DBEM (5.7 ± 0.8, 6.3 ± 1.2 and 11.1 ± 1.6) and DBMEL kids (5.3 ± 0.8, 8.0 ± 1.2 and 9.1 ± 1.6) were no different to those of DB kids (P > 0.05). HAND kids showed no change in cortisol over time (P > 0.10) and performed fewer rump movements, tail shakes and vocalizations than all treatments (P ≤ 0.01). In conclusion, lidocaine injection using a ring block appears to cause more pain than handling alone and may not reduce pain associated with cautery disbudding; therefore, a lidocaine ring block may not be a useful pain mitigation strategy for disbudding dairy goat kids. There was no evidence that meloxicam reduced acute pain and EMLA cream may have intensified the pain associated with disbudding. Further research on efficacious pain mitigation strategies for cautery disbudding of dairy goat kids is required.

The Effectiveness of EMLA as a Primary Dressing on Painful Chronic Leg Ulcers: Effects on Wound Healing and Health-Related Quality of Life

This study aimed to evaluate the effect of EMLA 5% cream applied to painful chronic leg ulcers (CLUs) as a primary dressing on wound healing and health-related quality of life (HRQoL). A pilot, parallel-group, nonblinded, randomized controlled trial was conducted in 6 community nursing procedure clinics in New South Wales, Australia. A total of 60 participants with painful CLUs of varied etiology were randomly assigned to the intervention (EMLA daily for 4 weeks as a primary dressing, followed by usual care) or usual care only. Wound size and HRQoL were measured at baseline, end of the intervention period (week 4), and week 12. At baseline, wound sizes were similar for both the intervention and control groups. During the intervention period, there was no significant difference in wound sizes between groups (intervention group: median (cm²) = 2.4, IQR = 1.3-12.7; control group: median (cm²) = 5.0, IQR = 2.5-9.9; P = .05). Mean HRQoL scores for all subscales at baseline and weeks 4 and 12 were similar between groups except for Wellbeing, which was significantly higher in the intervention group at the end of the 4-week intervention period (intervention group: mean = 52.41, SD = 24.50; control group: mean = 38.15, SD = 21.25; P = .03; d = 0.62). The trial findings suggest that daily applications of EMLA as a primary dressing do not inhibit wound healing and may improve patient well-being. Studies with larger samples are required to more comprehensively evaluate the impact of this treatment on wound healing and HRQoL.

Influences of high-voltage electrical burns on the pulmonary microcirculation in rabbits

This study was performed to investigate the effects of high-voltage electrical burns (HEB) on the pulmonary microcirculation in rabbits. Total of 120 rabbits were randomly divided into control and HEB group using a random number table. HEB model was developed with a voltage regulator and experimental transformer. Laser Doppler perfusion imager was utilized to monitor and quantify the blood perfusion in pulmonary microcirculation. The microvascular morphologic changes of the lung were observed using light microscopy and transmission electron microscope (TEM). The lung wet/dry weight ratio and the PaO2 were determined. The values of blood perfusion in rabbit pulmonary microcirculation in the HEB group were decreased at 5 min, but increased at 1 h after burn (P <  0.01) and then decreased gradually. Light microscopy reveals microthrombus formation in pulmonary venules and bleeding in venous capillaries in HEB group. We found the number of microvilli in the capillary endothelial cells decreased, the rough endoplasmic reticulum expanded and severe degranulation occurred, the mitochondrial cristae fused or disappeared, and severe edema surrounded the capillary endothelial cells by TEM. The values of lung wet/dry weight ratio were higher and the PaO2 were lower than that of before burn group (P <  0.01). These results demonstrated that microcirculatory disorders play a major role in the development of progressive lung damage after high-voltage electrical burns.

Pharmacokinetics and pharmacodynamics of lignocaine: A review

Lignocaine is an essential drug on World Health Organisation essential drug list, considered efficacious, safe and cost-effective for any health-care system. Despite its ubiquitous use in medicine and surgery, there are few detailed reviews of its pharmacokinetics and pharmacodynamics. Being an amide-type local anesthetic and Class 1b antiarrhythmic, lignocaine is most frequently used clinically for its anesthetic and antiarrhythmic benefits. However, lignocaine has important antinociceptive, immuno-modulating, and anti-inflammatory properties. Information pertaining to the pharmacokinetics and pharmacodynamics of lignocaine was examined by performing a literature search of PubMed, Embase and MEDLINE (via Ovid), pharmacology textbooks and online sources. We present a focused synopsis of lignocaine’s pharmacological composition, indications for use and mechanisms of action, focusing on its anti-inflammatory, immuno-modulating and analgesia effects. In addition we review the dosing regimes and infusion kinetics of lignocaine in the clinical setting. Finally, we review the evidence for ligocaine’s modulation of the inflammatory response during major surgery and its specific effects on cancer recurrence. These indirect effects of local anesthetics in tumor development may stem from the reduction of neuroendocrine responses to the stress response elicited by major surgery and tissue damage, enhanced preservation of immune-competence, in addition to opioid-sparing effects of modulating tumor growth.

Continuous subcutaneous instillation of bupivacaine compared to saline reduces interleukin 10 and increases substance P in surgical wounds after cesarean delivery

BACKGROUND

Recent evidence suggests that locally delivered local anesthetics may exert tissue-damaging effects such as chondrolysis after intraarticular injection. Alteration of the inflammatory response is a potential mechanism for local anesthetic-induced tissue toxicity. In this study, we tested the effects of continuous local anesthetic infiltration on the release of inflammatory and nociceptive mediators in skin wounds after cesarean delivery.

METHODS

Thirty-eight healthy women undergoing cesarean delivery with spinal anesthesia were enrolled in this study, and were randomized to receive subcutaneous surgical wound infiltration with bupivacaine 5 mg/mL or saline at 2 mL/h for 24 hours after cesarean delivery. Wound exudate was sampled at 1, 3, 5, 7, and 24 hours after cesarean delivery using a subcutaneous wound drain technique. Cytokines, chemokines, substance P, prostaglandin E(2), and nerve growth factor were assayed using multiplex Bio-Plex® (Bio-Rad, Hercules, CA) and enzyme-linked immunosorbent assays.

RESULTS

Bupivacaine wound infusion resulted in a significant decrease of interleukin 10 and increase of substance P in wounds compared with saline infusion (area under the 24-hour concentration-time curve; P < 0.001). No statistically significant differences were detected for other cytokines, nerve growth factor, and prostaglandin E(2).

CONCLUSIONS

This study demonstrates that the continuous administration of clinically used doses of bupivacaine into wounds affects the local composition of wound mediators. Observed changes in interleukin 10 are compatible with a disruption of antiinflammatory mechanisms. Whether such modulation combined with the release of the proinflammatory mediator substance P results in an overall proinflammatory wound response will require future studies of wound healing.

The impact of lidocaine on flap survival following reperfusion injury

BACKGROUND

Inflammatory events triggered by the mediators released from free oxygen radicals and infiltrated leukocytes play a direct role in formation of the ischemia-reperfusion (IR) injury. The aim of this study was to investigate the impact of lidocaine on IR injury due to its anti-inflammatory properties.

MATERIALS AND METHODS

Following delivery of lidocaine to the ischemic flaps in two different doses prior to the reperfusion, flap survival, malondialdehyde (MDA) level, myeloperoxidase (MPO) level, neutrophil count, and measurement of vascular diameters were studied. Twelve hours after reperfusion, tissue specimens were collected for measurement of MDA level, MPO level, neutrophil count, and vascular diameters. Flap survival was evaluated on the fifth day.

RESULTS

Flap survival rate was 15.54% ± 8.23% in the control group, whereas the groups treated wtih lidocaine showed remarkable elevations in survival rates as follows: 70.83% ± 33.53% and 67.42% ± 30.81%, respectively. MDA levels in sham and lidocaine treatment groups were significantly lower than those observed in control group.

CONCLUSION

Lidocaine inhibited the increase in MDA level associated with IR injury while showing no influence over increases in number of neutrophils and tissue MPO level, and it elevated the flap survival rate.

The use of lidocaine as an anti-inflammatory substance: a systematic review

OBJECTIVE

To investigate existence of evidence that supports the therapeutical use of lidocaine as an anti-inflammatory substance.

METHODS

A search on health sciences databases was performed, including only papers published in English until May 2007 which reported in vivo experimental studies that tested lidocaine as an anti-inflammatory substance and used morphological and/or biochemical analysis. The keywords used were: "lidocaine & inflammation", "lidocaine & neutrophils" and "lidocaine & prostaglandin". The search results were previous selected by title and abstract, and then articles were read and those that met inclusion criteria were carefully analyzed and classified.

RESULTS

Only 10 articles met the inclusion criteria, and were carefully read. They were ranked (A, B, and C) according to the level of evidence produced. Seven articles were classified as C, two classified as B, and one classified as A. Despite methodological differences, all of them, except for one, reported that lidocaine showed anti-inflammatory effects.

CONCLUSIONS

According to the reviewed literature, lidocaine has a potential as an anti-inflammatory agent. However, there is still a lack of well-designed studies to support its clinical use, and none of them evaluated its effects on a mucous epithelium.

The differential effects of bupivacaine and lidocaine on prostaglandin E2 release, cyclooxygenase gene expression and pain in a clinical pain model

BACKGROUND

In addition to blocking nociceptive input from surgical sites, long-acting local anesthetics might directly modulate inflammation. In the present study, we describe the proinflammatory effects of bupivacaine on local prostaglandin E2 (PGE2) production and cyclooxygenase (COX) gene expression that increases postoperative pain in human subjects.

METHODS

Subjects (n = 114) undergoing extraction of impacted third molars received either 2% lidocaine or 0.5% bupivacaine before surgery and either rofecoxib 50 mg or placebo orally 90 min before surgery and for the following 48 h. Oral mucosal biopsies were taken before surgery and 48 h after surgery. After extraction, a microdialysis probe was placed at the surgical site for PGE2 and thromboxane B2 (TXB2) measurements.

RESULTS

The bupivacaine/rofecoxib group reported significantly less pain, as assessed by a visual analog scale, compared with the other three treatment groups over the first 4 h. However, the bupivacaine/placebo group reported significantly more pain at 24 h and PGE2 levels during the first 4 h were significantly higher than the other three treatment groups. Moreover, bupivacaine significantly increased COX-2 gene expression at 48 h as compared with the lidocaine/placebo group. Thromboxane levels were not significantly affected by any of the treatments, indicating that the effects seen were attributable to inhibition of COX-2, but not COX-1.

CONCLUSIONS

These results suggest that bupivacaine stimulates COX-2 gene expression after tissue injury, which is associated with higher PGE2 production and pain after the local anesthetic effect dissipates.

Anesthetics impact the resolution of inflammation

BACKGROUND

Local and volatile anesthetics are widely used for surgery. It is not known whether anesthetics impinge on the orchestrated events in spontaneous resolution of acute inflammation. Here we investigated whether a commonly used local anesthetic (lidocaine) and a widely used inhaled anesthetic (isoflurane) impact the active process of resolution of inflammation.

METHODS AND FINDINGS

Using murine peritonitis induced by zymosan and a systems approach, we report that lidocaine delayed and blocked key events in resolution of inflammation. Lidocaine inhibited both PMN apoptosis and macrophage uptake of apoptotic PMN, events that contributed to impaired PMN removal from exudates and thereby delayed the onset of resolution of acute inflammation and return to homeostasis. Lidocaine did not alter the levels of specific lipid mediators, including pro-inflammatory leukotriene B(4), prostaglandin E(2) and anti-inflammatory lipoxin A(4), in the cell-free peritoneal lavages. Addition of a lipoxin A(4) stable analog, partially rescued lidocaine-delayed resolution of inflammation. To identify protein components underlying lidocaine's actions in resolution, systematic proteomics was carried out using nanospray-liquid chromatography-tandem mass spectrometry. Lidocaine selectively up-regulated pro-inflammatory proteins including S100A8/9 and CRAMP/LL-37, and down-regulated anti-inflammatory and some pro-resolution peptides and proteins including IL-4, IL-13, TGF-â and Galectin-1. In contrast, the volatile anesthetic isoflurane promoted resolution in this system, diminishing the amplitude of PMN infiltration and shortening the resolution interval (Ri) approximately 50%. In addition, isoflurane down-regulated a panel of pro-inflammatory chemokines and cytokines, as well as proteins known to be active in cell migration and chemotaxis (i.e., CRAMP and cofilin-1). The distinct impact of lidocaine and isoflurane on selective molecules may underlie their opposite actions in resolution of inflammation, namely lidocaine delayed the onset of resolution (T(max)), while isoflurane shortened resolution interval (Ri).

CONCLUSIONS

Taken together, both local and volatile anesthetics impact endogenous resolution program(s), altering specific resolution indices and selective cellular/molecular components in inflammation-resolution. Isoflurane enhances whereas lidocaine impairs timely resolution of acute inflammation.

Attenuating phosphorylation of p38 MAPK in the activated microglia: a new mechanism for intrathecal lidocaine reversing tactile allodynia following chronic constriction injury in rats

Increasing evidences approve the long-term analgesia effects of intrathecal lidocaine in patients with chronic pain and in animal peripheral nerve injury models, but the underlying mechanism remains elusive. Previous evidences suggest that the activation of the p38 MAPK signaling pathway in hyperactive microglia in the dorsal horn of spinal cord involves in nerve injury-induced neuropathic pain. In this study, we demonstrate that attenuating phosphorylation of p38 MAPK in the activated microglia of spinal cord, at least partly, is the mechanism of intrathecal lidocaine reversing established tactile allodynia in chronic constriction injury model of rats. This finding not only provides a new insight into the mechanisms underlying long-term therapeutic effects of lidocaine on neuropathic pain, but also reveals one more specific drug target for analgesia.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.

Selective diagnostic nerve root block for the evaluation of radicular pain in the multilevel degenerated cervical spine

In patients with radiculopathy due to degenerative disease in the cervical spine, surgical outcome is still presenting with moderate results. The preoperative investigations consist of clinical investigation, careful history and most often magnetic resonance imaging (MRI) of the cervical spine. When MRI shows multilevel degeneration, different strategies are used for indicating which nerve root/roots are affected. Some authors use selective diagnostic nerve root blocks (SNRB) for segregating pain mediating nerve roots from non-pain mediators in such patients. The aim of the present study is to assess the ability of transforaminal SNRB to correlate clinical symptoms with MRI findings in patients with cervical radiculopathy and a two-level MRI degeneration, on the same side as the radicular pain. Thirty consecutive patients with cervical radiculopathy and two levels MRI pathology on the same side as the radicular pain were studied with SNRBs at both levels. All patients underwent clinical investigation and neck and arm pain assessment with visual analogue scales (VAS) before and after the blocks. The results from the SNRBs were compared to the clinical findings from neurological investigation as well as the MRI pathology and treatment results. Correlation between SNRB results and the level with most severe degree of MRI degeneration were 60% and correlation between SNRB results and levels decided by neurological deficits/dermatome radicular pain distribution were 28%. Twenty-two of the 30 patients underwent treatment guided by the SNRB results and 18 reported good/excellent outcome results. We conclude that the degree of MRI pathology, neurological investigation and the pain distribution in the arm are not reliable parameters enough when deciding the affected nerve root/roots in patients with cervical radiculopathy and a two-level degenerative disease in the cervical spine. SNRB might be a helpful tool together with clinical findings/history and MRI of the cervical spine when performing preoperative investigations in patients with two or more level of degeneration presenting with radicular pain that can be attributed to the degenerative findings.