Ketamine as an adjuvant in sympathetic blocks for management of central sensitization following peripheral nerve injury

The Role of Intravenous Anesthetics for Neuro: Protection or Toxicity?

The primary intravenous anesthetics employed in clinical practice encompass dexmedetomidine (Dex), propofol, ketamine, etomidate, midazolam, and remimazolam. Apart from their established sedative, analgesic, and anxiolytic properties, an increasing body of research has uncovered neuroprotective effects of intravenous anesthetics in various animal and cellular models, as well as in clinical studies. However, there also exists conflicting evidence pointing to the potential neurotoxic effects of these intravenous anesthetics. The role of intravenous anesthetics for neuro on both sides of protection or toxicity has been rarely summarized. Considering the mentioned above, this work aims to offer a comprehensive understanding of the underlying mechanisms involved both in the central nerve system (CNS) and the peripheral nerve system (PNS) and provide valuable insights into the potential safety and risk associated with the clinical use of intravenous anesthetics.

TNFα in MS and Its Animal Models: Implications for Chronic Pain in the Disease

Multiple Sclerosis (MS) is a debilitating autoimmune disease often accompanied by severe chronic pain. The most common type of pain in MS, called neuropathic pain, arises from disease processes affecting the peripheral and central nervous systems. It is incredibly difficult to study these processes in patients, so animal models such as experimental autoimmune encephalomyelitis (EAE) mice are used to dissect the complex mechanisms of neuropathic pain in MS. The pleiotropic cytokine tumor necrosis factor α (TNFα) is a critical factor mediating neuropathic pain identified by these animal studies. The TNF signaling pathway is complex, and can lead to cell death, inflammation, or survival. In complex diseases such as MS, signaling through the TNFR1 receptor tends to be pro-inflammation and death, whereas signaling through the TNFR2 receptor is pro-homeostatic. However, most TNFα-targeted therapies indiscriminately block both arms of the pathway, and thus are not therapeutic in MS. This review explores pain in MS, inflammatory TNF signaling, the link between the two, and how it could be exploited to develop more effective TNFα-targeting pain therapies.

Transversus Abdominis Plane (TAP) Block: A Comparative Study between Levobupivacaine versus Levobupivacaine plus Ketamine in Abdominoplasty

Purpose

We conducted this study to explore the hypothesis that the addition of ketamine to levobupivacaine in ultrasound-guided Transversus Abdominis Plane (TAP) block would result in a better and prolonged duration of postoperative analgesia for patients undergoing abdominoplasty. Material and Methods. This randomized prospective study was conducted on 50 patients who were scheduled for abdominoplasty. TAP block was performed bilaterally for all patients either with levobupivacaine 0.5% 15 ml plus ketamine 0.5 mg/kg in a total volume of 20 ml in the LK group (n = 25) or with levobupivacaine 0.5% 15 ml plus 5 ml normal saline in a total volume of 20 ml in the L group on each side.

Results

Visual analogue scale (VAS) was significantly lower in the LK group in resting condition at 6, 12, and 16 h postoperatively compared to the L group. On movement, the VAS was significantly lower at 4, 6, 8, 12, 16, and 24 h postoperatively in the LK group compared to the L group. The time for first rescue analgesia was longer in the LK group (18.7 ± 4.8 h) than that in the L group (6.5 ± 2.4 h) with the reduced total amount of rescue morphine in the LK group (1.14 ± 2.2 mg) versus the L group (5.86 ± 3.6 mg). Only six patients in the LK group requested rescue morphine, whereas nineteen patients requested rescue morphine in the L group.

Conclusions

In TAP block, adding ketamine 0.5 mg/kg enhanced the analgesic efficacy of levobupivacaine 0.5% in patients undergoing abdominoplasty and reduced the required analgesics postoperatively.

Adjuvant Drugs for Peripheral Nerve Blocks: The Role of NMDA Antagonists, Neostigmine, Epinephrine, and Sodium Bicarbonate

The potential for misuse, overdose, and chronic use has led researchers to look for other methods to decrease opioid consumption in patients with acute and chronic pain states. The use of peripheral nerve blocks for surgery has gained increasing popularity as it minimizes peripheral pain signals from the nociceptors of local tissue sustaining trauma and inflammation from surgery. The individualization of peripheral nerve blocks using adjuvant drugs has the potential to improve patient outcomes and reduce chronic pain. The major limitations of peripheral nerve blocks are their limited duration of action and dose-dependent adverse effects. Adjuvant drugs for peripheral nerve blocks show increasing potential as a solution for postoperative and chronic pain with their synergistic effects to increase the duration of action and decrease the required dosage of local anesthetic. N-methyl-d-aspartate (NMDA) receptor antagonists are a viable option for patients with opioid resistance and neuropathic pain due to their affinity to the neurotransmitter glutamate, which is released when patients experience a noxious stimulus. Neostigmine is a cholinesterase inhibitor that exerts its effect by competitively binding at the active site of acetylcholinesterase, which prevents the hydrolysis of acetylcholine and subsequently retaining acetylcholine at the nerve terminal. Epinephrine, also known as adrenaline, can potentially be used as an adjuvant to accelerate and prolong analgesic effects in digital nerve blocks. The theorized role of sodium bicarbonate in local anesthetic preparations is to increase the pH of the anesthetic. The resulting alkaline solution enables the anesthetic to more readily exist in its un-ionized form, which more efficiently crosses lipid membranes of peripheral nerves. However, more research is needed to show the efficacy of these adjuvants for nerve block prolongation as studies have been either mixed or have small sample sizes.

Pre-emptive multimodal analgesia with tramadol and ketamine-lidocaine infusion for suppression of central sensitization in a dog model of ovariohysterectomy

Objectives

The effects of pre-emptive infusion of ketamine-lidocaine with tramadol on the suppression of central sensitization were investigated in a dog ovariohysterectomy model.

Patients and methods

Twelve dogs were randomly assigned to two groups: ketamine-lidocaine-tramadol (KLT) and tramadol (T) groups. Both groups received intravenous tramadol 4 mg/kg body weight as premedication. Immediately after induction, the KLT group received ketamine and lidocaine at 0.5 and 2 mg/kg loading dose, followed by continuous rate infusion of 50 and 100 µg/kg/min, respectively, for 2 hours. Dogs in T group received saline bolus and continuous rate infusion at equi-volume. Intraoperatively, hemodynamic responses to surgical stimulation were recorded, whereas postoperative pain was evaluated using an algometer and short form of the Glasgow composite measure pain scale.

Results

Intraoperatively, hemodynamic responses to surgical stimulation were obtunded to a greater degree in KLT compared to T group. Postoperatively, the pain scores increased only for the first hour in KLT group, compared to 12 hours in T group. Mechanical thresholds at the abdomen decreased postoperatively between 12 and 60 hours in KLT group versus the entire 72 hours in T group. Thresholds at tibia and radius in both groups increased in the immediate 1 hour postoperatively, but decreased thereafter. Significant decrement of thresholds from baseline were detected in the tibia at 24, 42, and 60 hours in KLT group compared to 24-72 hours in T group, and in the radius between 36 and 48 hours in T group, but none in KLT group.

Conclusion

Addition of pre-emptive ketamine-lidocaine infusion to single intravenous dose of tramadol enhanced attenuation of central sensitization and improved intra- and postoperative analgesia.

The Effect of Ketamine and Dexamethasone in Combination with Lidocaine on the Onset and Duration of Axillary Block in Hand and Forearm Soft Tissue Surgery

Background

Using peripheral nerve block compared to general anesthesia has gained more popularity due to reduced postoperative pain, less need for post-surgery analgesic drugs, reduced incidence of nausea, shortness of PACU time, and increased patient satisfaction.

Objectives

The aim of this study was to compare the effect of ketamine and dexamethasone as additives to lidocaine on duration and onset of axillary block action.

Methods

In this clinical trial, all patients who referred to Hazrat-e-Fatemeh hospital for forearm and hand soft tissue surgery with informed consent were randomly divided into three groups in order to examine the onset and duration of axillary block: lidocaine + ketamine, lidocaine + dexamethasone in axillary block, and lidocaine alone (control). Then, the onset and duration of sensory and motor blocks were measured and recorded every three minutes and after the surgery. Quantitative and qualitative variables were analyzed using ANOVA or Kruskal-Wallis test and Chi-square or Fisher exact test in SPSS v.22.

Results

Duration of sensory and motor block axillary was significantly higher in lidocaine + dexamethasone group than in lidocaine + ketamine group (P < 0.05); it was also significantly higher in lidocaine + ketamine group compared to lidocaine group (P < 0.05). However, there was no significant difference in the onset of sensory and motor block axillary between the three groups (P > 0.05).

Conclusions

According to the results of our study, we can conclude that adding dexamethasone or ketamine to lidocaine could improve duration of sensory and motor axillary block in patients undergoing forearm and hand soft tissue surgery. However, dexamethasone had the highest effect on duration of block axillary. We proved that dexamethasone or ketamine added to lidocaine had no effect on the onset of block axillary.

Effect of preinduction low-dose ketamine bolus on intra operative and immediate postoperative analgesia requirement in day care surgery: A randomized controlled trial

BACKGROUND

Availability of narcotics is an issue in developing countries, and low-dose ketamine offers an alternative to these drugs.

OBJECTIVE

The objective of this study is to evaluate the effect of a preemptive dose of low-dose ketamine on intra operative and the immediate postoperative analgesic requirements.

DESIGN

Randomized double-blind control trial.

SETTINGS

This study has been performed in the operating rooms and postanesthesia care unit at Aga Khan University Hospital, Karachi, Pakistan.

MATERIALS AND METHODS

Totally, 60 adult American Society of Anesthesiologists I and II patients undergoing day care surgery were randomly allocated into two groups, Group A (ketamine group) and Group B (saline group).

INTERVENTION

All patients underwent general anesthesia. Propofol 2 mg/kg was used as an induction agent; laryngeal mask airway (size 3 for females and 4 for males) was inserted. Following induction patients in Group A received ketamine 0.3 mg/kg and Group B saline bolus in a blinded manner. All patients were administered injection fentanyl 1 μg/kg as an analgesic and anesthesia was maintained with oxygen 40%, nitrous oxide 60% and isoflorane 1-2 minimum alveolar concentration. Patients breathed spontaneously on Lack circuit. Postoperatively rescue analgesia was provided with intravenous morphine 0.1 mg/kg when patient complained of pain.

MAIN OUTCOME MEASURES

We observed analgesic effects of low-dose ketamine intra operatively and narcotic requirements in immediate postoperative period for day care surgeries.

RESULTS

There was no significant difference in demographic data in between groups. Saline group required more rescue analgesia (morphine) postoperatively (P < 0.001). No significant psychotomimetic symptoms were noted in either group.

CONCLUSION

Low-dose ketamine 0.3 mg/kg provided adequate co-analgesia with fentanyl 1 μg/kg and was effective in a reduction of morphine requirement in the postoperative phase with minimal adverse effects.

Preventive Treatment with Ketamine Attenuates the Ischaemia-Reperfusion Response in a Chronic Postischaemia Pain Model

Ischemia and inflammation may be pathophysiological mechanisms of complex regional pain syndrome (CRPS). Ketamine has proposed anti-inflammatory effects and has been used for treating CRPS. This study aimed to evaluate anti-inflammatory and analgesic effects of ketamine after ischaemia-reperfusion injury in a chronic postischaemia pain (CPIP) model of CRPS-I. Using this model, ischemia was induced in the hindlimbs of male Sprague-Dawley rats. Ketamine, methylprednisolone, or saline was administered immediately after reperfusion. Physical effects, (oedema, temperature, and mechanical and cold allodynia) in the bilateral hindpaws, were assessed from 48 hours after reperfusion. Fewer (56%) rats in the ketamine group developed CPIP at the 48th hour after reperfusion (nonsignificant). Ketamine treated rats showed a significantly lower temperature in the ischaemic hindpaw compared to saline (P < 0.01) and methylprednisolone (P < 0.05) groups. Mechanical and cold allodynia were significantly lower in the ischaemic side in the ketamine group (P < 0.05). Proinflammatory cytokines TNF-α and IL-2 were significantly lower at the 48th hour after reperfusion in ketamine and methylprednisolone groups, compared to saline (all P < 0.05). In conclusion, immediate administration of ketamine after an ischaemia-reperfusion injury can alleviate pain and inflammation in the CPIP model and has potential to treat postischaemic pain.

Epigenetic modification of DRG neuronal gene expression subsequent to nerve injury: etiological contribution to complex regional pain syndromes (Part II)

Cumulating evidence indicated that nerve injury-associated cellular and molecular changes play an essential role in contributing to the development of pathological pain, and more recent findings implicated the critical role of epigenetic mechanisms in pain-related sensitization in the DRG subsequent to nerve injury. In this part of the dyad review (Part II), we reviewed and paid special attention on the etiological contribution of DGR gene expression modulated by epigenetic mechanisms of CRPS. As essential effectors to different molecular activation, we first discussed the activation of various signaling pathways that subsequently from nerve injury, and in further illustrated the fundamental and functional underpinnings of nerve injury-induced pain, in which we argued for the potential epigenetic mechanisms in response to sensitizing stimuli or injury. Therefore, understanding the specific mediating factors that influence individual epigenetic differences contributing to pain sensitivity and responsiveness to analgesics possesses crucial clinical implications.

Efficacy and safety of ketamine in patients with complex regional pain syndrome: a systematic review

Despite being a recognized clinical entity for over 140 years, complex regional pain syndrome (CRPS) remains a difficult-to-treat condition. While there have been multiple therapies explored in the treatment of CRPS, NMDA antagonists such as ketamine continue to hold significant interest because of their potential ability to alter the central sensitization noted in chronic pain states. The objective of this review is to identify published literature for evidence of the efficacy and safety of ketamine in the treatment of CRPS. PubMed and the Cochrane Controlled Trials Register were searched (final search 26 May 2011) using the MeSH terms 'ketamine', 'complex regional pain syndrome', 'analgesia' and 'pain' in the English literature. The manuscript bibliographies were then reviewed to identify additional relevant papers. Observational trials were evaluated using the Agency for Healthcare Research and Quality criteria; randomized trials were evaluated using the methodological assessment of randomized clinical trials. The search methodology yielded three randomized, placebo-controlled trials, seven observational studies and nine case studies/reports. In aggregate, the data available reveal ketamine as a promising treatment for CRPS. The optimum dose, route and timing of administration remain to be determined. Randomized controlled trials are needed to establish the efficacy and safety of ketamine and to determine its long-term benefit in CRPS.

Ketamine use: a review

AIMS

Ketamine remains an important medicine in both specialist anaesthesia and aspects of pain management. At the same time, its use as a recreational drug has spread in many parts of the world during the past few years. There are now increasing concerns about the harmful physical and psychological consequences of repeated misuse of this drug. The aim of this review was to survey and integrate the research literature on physical, psychological and social harms of both acute and chronic ketamine use.

METHOD

The literature on ketamine was systematically searched and findings were classified into the matrix of Nutt et al.'s (2007) rational scale for assessing the harms of psychoactive substances.

RESULTS

A major physical harm is ketamine induced ulcerative cystitis which, although its aetiology is unclear, seems particularly associated with chronic, frequent use of the drug. Frequent, daily use is also associated with neurocognitive impairment and, most robustly, deficits in working and episodic memory. Recent studies suggest certain neurological abnormalities which may underpin these cognitive effects. Many frequent users are concerned about addiction and report trying but failing to stop using ketamine.

CONCLUSIONS

The implications of these findings are drawn out for treatment of ketamine-induced ulcerative cystitis in which interventions from urologists and from addiction specialists should be coordinated. Neurocognitive impairment in frequent users can impact negatively upon achievement in education and at work, and also compound addiction problems. Prevention and harm minimization campaigns are needed to alert young people to these harmful and potentially chronic effects of ketamine.

Efficacy of stellate ganglion block with an adjuvant ketamine for peripheral vascular disease of the upper limbs

Stellate ganglion block (STGB) is commonly indicated in painful conditions like reflex sympathetic dystrophy, malignancies of head and neck, Reynaud’s disease and vascular insufficiency of the upper limbs. The sympathetic blockade helps to relieve pain and ischaemia. Diagnostic STGB is usually performed with local anaesthetics followed by therapeutic blockade with steroids, neurolytic agents or radiofrequency ablation of ganglion. There is increasing popularity and evidence for the use of adjuvants like opioid, clonidine and N Methyl d Aspartate (NMDA) receptor antagonist – ketamine – for the regional and neuroaxial blocks. The action of ketamine with sympatholytic block is through blockade of peripherally located NMDA receptors that are the target in the management of neuropathic pain, with the added benefit of counteracting the “wind-up” phenomena of chronic pain. We studied ketamine as an adjuvant to the local anaesthetic for STGB in 20 cases of peripheral vascular disease of upper limbs during the last 5 years at our institution. STGB was given for 2 days with 2 ml of 2% lignocaine + 8 ml of 0.25% bupivacaine, followed by block with the addition of 0.5 mg/kg of ketamine for three consecutive days. There was significant pain relief of longer duration with significant rise in hand temperature. We also observed complete healing of the gangrenous fingers in 17/19 patients.