The in vitro mechanisms and in vivo efficacy of intravenous lidocaine on the neuroinflammatory response in acute and chronic pain

Beyond Opioids for Pain Management in Adult Critically Ill Patients

Critically ill patients commonly experience pain, and the provision of analgesia is an essential component of intensive care unit (ICU) care. Opioids are the mainstay of pain management in the ICU but are limited by their adverse effects, risk of addiction and abuse, and recent drug shortages of injectable formulations. A multimodal analgesia approach, utilizing nonopioid analgesics as adjuncts to opioid therapy, is recommended since they may modulate the pain response and reduce opioid requirements by acting on multiple pain mediators. Nonopioid analgesics discussed in detail in this article are acetaminophen, α-2 receptor agonists, gabapentinoids, ketamine, lidocaine, and nonsteroidal anti-inflammatory drugs. This literature review describes the clinical pharmacology, supportive ICU and relevant non-ICU data, and practical considerations associated with the administration of nonopioid analgesics in critically ill adult patients.

The analgesic efficacy and duration of lidocaine on vascular pain induced by hypertonic saline infusion: a double-blinded, randomized control trial

PURPOSE

To determine the analgesic efficacy and analgesic duration of lidocaine 20 mg and 40 mg on eliminating the vascular pain associated with hypertonic saline infusion.

METHOD

Patients who complained pain during infusion of hypertonic saline were randomized into three groups. They received normal saline (Group C), or lidocaine 20 mg (Group L20), or lidocaine 40 mg (Group L40). An electronic stopwatch was used to record the time to onset (T1) and the time to termination (T2) of the analgesic effect, and the analgesic duration (AD) was calculated as T2 - T1.

RESULTS

The incidence of pain elimination was significantly higher in both of the lidocaine groups (83.3 and 56.1% in Groups L40 and L20, respectively) than in the saline group (16.3%). Furthermore, lidocaine 40 mg was significantly more effective than 20 mg in eliminating the pain. The analgesic duration was significantly longer in Group L40 than in Group L20 (211.4 ± 50.2 vs. 130.3 ± 39.5 s, P < 0.001) and Group C (211.4 ± 50.2 vs. 45.1 ± 14.5 s, P < 0.001), and the analgesic duration in Group L20 was significantly longer than in Group C (P < 0.001). The incidence of transient tinnitus/dizziness was significantly higher in Group L40 than in Group L20 (19.0 vs. 2.4%, P < 0.05).

CONCLUSION

A single bolus of Lidocaine was effective in eliminating the pain induced by hypertonic saline infusion, but just for a short period of time. Lidocaine (without venous occlusion) only provides a short analgesic duration for local vein.

Comparison of Efficacy Outcomes of Lidocaine Spray, Topical Lidocaine Injection, and Lidocaine General Anesthesia in Nasal Bone Fractures Surgeries: A Randomized, Controlled Trial

Background

Lidocaine is widely used as a general and local anesthetic in minor or major surgeries. The objective of the study was to compare postoperative pain relief and adverse events using different forms of lidocaine administration in patients following closed nasal bone reduction surgery.

Material/Methods

A total of 381 patients with a solitary nasal fracture that could be managed with closed reduction were included in this study and divided into 3 groups of 127 patients in each group. Patients had received 1% lidocaine HCl with epinephrine (LL group), inserted a mesh impregnated with lidocaine spray (TL group), or 1 mg/kg/h lidocaine infusion (GL group) before surgeries. Patients also received morphine when the pain was not controlled. The postoperative pain was assessed at 6 hours and 48 hours after surgery. Postoperative vomiting and nausea were evaluated. Repeated ANOVA/Tukey-Kramer multiple comparisons test was performed at 95% confidence level.

Results

At 6 hours after surgery, patients in the general lidocaine (GL) group reported decreased postoperative pain compared with those in the topical lidocaine (TL) group (P<0.001, q=6.633) and LL group (P<0.001, q=8.056). The morphine consumption within 48 hours was least in GL group than TL group (P<0.001, q=172.9) and LL group (P<0.001, q=226.42). Lidocaine infusion caused nausea (P<0.001, q=6.742) and vomiting (P<0.001, q=4.306).

Conclusions

Topical lidocaine anesthesia had the same postoperative pain relief and the least adverse events as local and general lidocaine anesthesia.

[Systemic effects of amide-linked local anesthetics : Old drugs, new magic bullets?]

Besides the well-known analgesic effects of amide-linked local anesthetics exerted via the inhibition of the voltage-gated sodium channel, these substances also possess a certain number of properties, which bear the potential to positively influence the outcome after surgery. The results of several experimental as well as clinical studies suggest the possibility of an enhanced recovery after surgery, reduction in the incidence of chronic pain, preservation of endothelial barrier function during acute lung injury and the prevention of metastasis of solid tumors by systemic effects of local anesthetic administration. Mechanistic studies were able to identify several "new targets", such as the inhibition of spinal glycine transporters or of inflammatory signaling as induced by tumor necrosis factor alpha. Further elucidation of these mechanistic pathways as well as the translation of these promising experimental results into clinical practice is a crucial component of research activities in the field of anesthesia.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

A Case Report of Refractory Notalgia Paresthetica Treated with Lidocaine Infusions

Patient: Female, 50

Final Diagnosis: Notalgia parethetica

Symptoms: Hyperalgesia • Pruritus

Medication: —

Clinical Procedure: Intravenous lidocaine infusion

Specialty: Anesthesiology

TRPA1 and TRPV1 are required for lidocaine-evoked calcium influx and neuropeptide release but not cytotoxicity in mouse sensory neurons

Background

Local anaesthetics (LA) reduce neuronal excitability by inhibiting voltage-gated Na⁺ channels. When applied at high concentrations in the direct vicinity of nerves, LAs can also induce relevant irritation and neurotoxicity via mechanisms involving an increase of intracellular Ca²⁺. In the present study we explored the role of the Ca²⁺-permeable ion channels TRPA1 and TRPV1 for lidocaine-induced Ca²⁺-influx, neuropeptide release and neurotoxicity in mouse sensory neurons.

Methods

Cultured dorsal root ganglion (DRG) neurons from wildtype and mutant mice lacking TRPV1, TRPA1 or both channels were explored by means of calcium imaging, whole-cell patch clamp recordings and trypan blue staining for cell death. Release of calcitonin gene-related peptide (CGRP) from isolated mouse peripheral nerves was determined with ELISA.

Results

Lidocaine up to 10 mM induced a concentration-dependent reversible increase in intracellular Ca²⁺ in DRG neurons from wildtype and mutant mice lacking one of the two receptors, but not in neurons lacking both TRPA1 and TRPV1. 30 mM lidocaine also released Ca²⁺ from intracellular stores, presumably from the endoplasmic reticulum. While 10 mM lidocaine evoked an axonal CGRP release requiring expression of either TRPA1 or TRPV1, CGRP release induced by 30 mM lidocaine again mobilized internal Ca²⁺ stores. Lidocaine-evoked cell death required neither TRPV1 nor TRPA1.

Summary

Depending on the concentration, lidocaine employs TRPV1, TRPA1 and intracellular Ca²⁺ stores to induce a Ca²⁺-dependent release of the neuropeptide CGRP. Lidocaine-evoked cell death does not seem to require Ca²⁺ influx through TRPV1 or TRPV1.

Enhanced recovery after surgery: Pain management

Effective pain management is fundamental to enhanced recovery after surgery. Selection of strategies should be tailored to patient and operation. As well as improving the quality of recovery, effective analgesia reduces the host stress response, facilitates mobilization and allows resumption of oral intake. Multi-modal regimens combining paracetamol, non-steroidal anti-inflammatory agents where indicated, a potent opioid and a local anaesthetic technique achieve effective analgesia while limiting the dose and thereby side effects of any one agent.

Local anaesthetic refinement of pentobarbital euthanasia reduces abdominal writhing without affecting immunohistochemical endpoints in rats

Sodium pentobarbital is a commonly used agent for euthanizing laboratory rats, however its high pH can cause abdominal discomfort after intraperitoneal injection. Previous studies suggest that the addition of a local anaesthetic may alleviate this discomfort, but the practice has not been widely adopted. We examined the effect of combining lidocaine with pentobarbital on abdominal writhing, defecation, ultrasonic vocalizations, the rat grimace scale and immunohistochemical staining for c-Fos in the nucleus accumbens and basolateral amygdala of the brain. We also compared the amount of abdominal writhing following intraperitoneal administration of pentobarbital–lidocaine with that of pentobarbital–bupivacaine. Our results show that lidocaine reduces abdominal writhing and defecation without affecting immunohistochemistry for c-Fos or latency to loss of posture. However, scores on the rat grimace scale were low in both situations and almost no ultrasonic vocalizations were recorded. Additionally, we found that the amount of abdominal writhing was not significantly different when bupivacaine was used rather than lidocaine. Our results suggest that pentobarbital-induced euthanasia can be refined with the addition of lidocaine or other local anaesthetics.

The Efficacy of Systemic Lidocaine in the Management of Chronic Pain: A Literature Review

Context

Despite recent advances in the understanding of the chronic pain concept, its diagnosis and management remains a daily challenge for clinicians and patients. Based on the published literature, this review discusses and tries to organize the current knowledge and the up-to-date clinical experience about the efficacy and safety of the use of intravenous lidocaine in treatment and prevention of chronic pain.

Evidence Acquisition

To prepare this narrative review, we performed an in depth literature review using the PubMed searching engine. We extracted all relevant articles published in English, up to April 2016.

Results

Lidocaine, administered as transdermal patch or intravenous lidocaine, is a safe and effective modality in the treatment of post-herpetic neuralgia (PHN), complex regional pain syndrome, as well and for prevention of chronic pain. It may be effective in the management of neuropathic pain syndromes, chronic pain, post-operative pain, and refractory cancer pain.

Conclusions

Intravenous lidocaine and lidocaine patch are effective and safe for the treatment of several chronic or neuropathic pain syndromes. The use of lidocaine during surgery could prevent the development of some chronic post-surgical pain syndromes.

Intravenous Lidocaine: Old-School Drug, New Purpose-Reduction of Intractable Pain in Patients with Chemotherapy Induced Peripheral Neuropathy

Background. Treatment of intractable pain due to chemotherapy induced peripheral neuropathy (CIPN) is a challenge. Intravenous (iv) lidocaine has shown to be a treatment option for neuropathic pain of different etiologies. Methods. Lidocaine (1.5 mg/kg in 10 minutes followed by 1.5 mg/kg/h over 5 hours) was administered in nine patients with CIPN, and analgesic effect was evaluated during infusion and after discharge. The immediate effect of lidocaine on pressure pain thresholds (PPT) and the extent of the stocking and glove distribution of sensory abnormalities (cold and pinprick) were assessed. Results. Lidocaine had a significant direct analgesic effect in 8 out of 9 patients (P = 0.01) with a pain intensity difference of >30%. Pain reduction persisted in 5 patients for an average of 23 days. Lidocaine did not influence mean PPT, but there was a tendency that the extent of sensory abnormalities decreased after lidocaine. Conclusion. Iv lidocaine has direct analgesic effect in CIPN with a moderate long-term effect and seems to influence the area of cold and pinprick perception. Additional research is needed, using a control group and larger sample sizes to confirm these results.

Perioperative regional anaesthesia and postoperative longer-term outcomes

Regional anaesthesia provides effective anaesthesia and analgesia in the perioperative setting. Central neuraxial blocks-that is, spinal and epidural blocks-are well established as an alternative or adjunct to general anaesthesia. Peripheral blocks may be used as part of multimodal anaesthesia/analgesia in perioperative practice, reducing the need for opioid analgesics and enhancing early recovery. Furthermore, regional anaesthesia has increased in popularity and may be done with improved ease and safety with the introduction of ultrasound-guided techniques. The effects of local anaesthetics and regional anaesthesia on long-term outcomes such as morbidity, mortality, the quality of recovery beyond the duration of analgesia, and whether it can expedite the resumption of activities of daily living are less clear. It has also been suggested that regional anaesthesia may impact the risk of metastasis after cancer surgery. This article provides an overview of current evidence around quality of recovery, risk for delirium, long-term effects, and possible impact on cancer disease progression associated with the clinical use of local and regional anaesthetic techniques. In summary, there is still a lack of robust data that regional anaesthesia has a clinical impact beyond its well-acknowledged beneficial effects of reducing pain, reduced opioid consumption, and improved quality of early recovery. Further high-quality prospective studies on long-term outcomes are warranted.

New modalities of neurostimulation: high frequency and dorsal root ganglion

PURPOSE OF REVIEW

Neurostimulation is a well tolerated, cost-efficient, and effective method to treat chronic pain. Although spinal cord stimulation (SCS) has been shown to help patients, newer modalities such as burst, kilohertz-frequency, and dorsal root ganglion stimulation may provide greater pain relief, fewer paresthesias, and better outcomes.

RECENT FINDINGS

Burst stimulation, programed as five-impulse burst at a frequency of 500 Hz, delivers more charge per second than conventional stimulation. Trials of burst stimulation have shown superior pain relief, decreased paresthesias, and patient preference compared with conventional SCS. Kilohertz-frequency SCS uses low-amplitude, high-frequency (10 kHz), and short-duration pulses. The SENZA trial showed superiority in both back and leg pain with greater pain relief as well as decreased opioid use. Dorsal root ganglion stimulation stimulates the ganglion cells allowing for precise targeting of pain regions. Multiple studies, including the ACCURATE trial, have shown superior pain relief in multiple conditions.

SUMMARY

Improvements in pain control and patient satisfaction suggest that these new stimulation patterns will greatly increase the utility of neurostimulation; however, clinical trials with broader patient populations have to be done to support more extensive use of these therapies.