Low-dose ketamine affects immune responses in humans during the early postoperative period

The impact of perioperative ketamine or esketamine on the subjective quality of recovery after surgery: a meta-analysis of randomised controlled trials

BACKGROUND

This meta-analysis aimed to evaluate the impact of ketamine/esketamine on postoperative subjective quality of recovery (QoR).

METHODS

MEDLINE, Embase, Cochrane library, and Google Scholar were searched for randomised controlled trials (RCTs) that examined the impacts of perioperative ketamine/esketamine use and postoperative QoR. The primary outcome was subjective QoR (QoR-9, QoR-15, QoR-40) on postoperative day (POD) 1-3, whereas the secondary outcomes included pain severity, anxiety scores, depression scores, risk of adverse events (i.e. nausea, vomiting, dizziness, drowsiness), and length of stay.

RESULTS

The analysis included 18 RCTs (1554 participants; ketamine: seven trials, esketamine: 11 trials), of which 15 were conducted in China. Ketamine/esketamine improved the QoR scores on PODs 1 and 2 compared with the control (standardised mean difference [SMD]: 0.63, P<0.0001 for POD 1; SMD: 0.56, P=0.04 for POD 2), without beneficial effect on POD 3. Subgroup analyses revealed significant differences in QoR scores on POD 1 by regimen (SMD: esketamine 1.14, ketamine 0.01) and country (SMD: China 0.82, other countries -0.21). The emotional domain of QoR was improved from PODs 1 to 3, whereas the other domains were only improved on POD 1. Lower postoperative anxiety (SMD: -0.48, P=0.003) and depression (SMD: -0.72, P=0.001) scores were also observed with ketamine/esketamine use. Furthermore, pain severity was reduced on PODs 1 and 2, with no difference in the risk of adverse events or length of stay.

CONCLUSIONS

This meta-analysis demonstrated that ketamine/esketamine use in the perioperative period is associated with improved early subjective QoR, pain severity, and psychological symptoms without an increase in the likelihood of adverse events.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42023477580).

Effects of esketamine on postoperative fatigue syndrome in patients after laparoscopic resection of gastric carcinoma: a randomized controlled trial

BACKGROUND

Despite the implementation of various postoperative management strategies, the prevalence of postoperative fatigue syndrome (POFS) remains considerable among individuals undergoing laparoscopic radical gastrectomy. While the N-methyl-D-aspartic acid receptor antagonist esketamine has demonstrated efficacy in enhancing sleep quality and alleviating postoperative pain, its impact on POFS remains uncertain. Consequently, the objective of this study is to ascertain whether perioperative administration of esketamine can effectively mitigate the occurrence of POFS in patients undergoing laparoscopic radical gastrectomy.

METHODS

A total of 133 patients diagnosed with gastric cancer were randomly assigned to two groups, namely the control group (Group C) (n = 66) and the esketamine group (Group E) (n = 67), using a double-blind method. The Group C received standardized anesthesia, while the Group E received esketamine in addition to the standardized anesthesia. The primary outcome measure assessed was the Christensen fatigue score at 3 days after the surgical procedure, while the secondary outcomes included the disparities in postoperative fatigue, postoperative pain, sleep quality, and adverse reactions between the two groups.

RESULTS

In the group receiving esketamine, the fatigue scores of Christensen on the third day after surgery were significantly lower compared to the Group C (estimated difference, -0.70; 95% CI, -1.37 to -0.03; P = 0.040). Additionally, there was a significant decrease in the occurrence of fatigue in the Group E compared to the Group C on the first and third days following surgery (P < 0.05). Also, compared to individuals who had distal gastrectomy, those who had entire gastrectomy demonstrated a higher degree of postoperative tiredness reduction with esketamine. Furthermore, the Group E exhibited reduced postoperative pain and improved sleep in comparison to the Group C. Both groups experienced similar rates of adverse events.

CONCLUSIONS

The use of esketamine during the perioperative period can improve POFS after laparoscopic radical gastrectomy, without adverse reactions.

TRIAL REGISTRATION

Registered in the Chinese Clinical Trial Registry (ChiCTR2300072167) on 05/06 /2023.

Ketamine's mechanism of action with an emphasis on neuroimmune regulation: can the complement system complement ketamine's antidepressant effects?

Over 300 million people worldwide suffer from major depressive disorder (MDD). Unfortunately, only 30-40% of patients with MDD achieve complete remission after conventional monoamine antidepressant therapy. In recent years, ketamine has revolutionized the treatment of MDD, with its rapid antidepressant effects manifesting within a few hours as opposed to weeks with conventional antidepressants. Many research endeavors have sought to identify ketamine's mechanism of action in mood disorders; while many studies have focused on ketamine's role in glutamatergic modulation, several studies have implicated its role in regulating neuroinflammation. The complement system is an important component of the innate immune response vital for synaptic plasticity. The complement system has been implicated in the pathophysiology of depression, and studies have shown increases in complement component 3 (C3) expression in the prefrontal cortex of suicidal individuals with depression. Given the role of the complement system in depression, ketamine and the complement system's abilities to modulate glutamatergic transmission, and our current understanding of ketamine's anti-inflammatory properties, there is reason to suspect a common link between the complement system and ketamine's mechanism of action. This review will summarize ketamine's anti- inflammatory roles in the periphery and central nervous system, with an emphasis on complement system regulation.

Perioperative Ketamine and Cancer Recurrence: A Comprehensive Review

Cancer is a significant global health threat and a leading cause of death worldwide. Effective early-stage interventions, particularly surgery, can potentially cure many solid tumors. However, the risk of postoperative cancer recurrence remains high. Recent research highlights the influence of perioperative anesthetic and analgesic choices on the fate of residual cancer cells, potentially affecting recurrence risks. Among these agents, ketamine-a well-known anesthetic and analgesic-has garnered interest due to its antitumor properties, mainly through inhibiting the N-methyl-D-aspartate (NMDA) receptor found in various cancer tissues. Additionally, ketamine's potential immunomodulatory effects, given the expression of NMDA receptors on immune cells, suggest that it plays a significant role during the perioperative period. This review synthesizes current evidence on ketamine's impact on cancer cell biology, inflammation, immune modulation, and the role of the gut microbiota, proposing ketamine as a promising agent for enhancing oncological outcomes.

Ketamine - A New Antidepressant Drug with Anti-Inflammatory Properties

Ketamine is a new, potent and rapid-acting antidepressant approved for therapy of treatment-resistant depression, which has a different mechanism of action than currently-available antidepressant therapies. It owes its uniquely potent antidepressant properties to a complex mechanism of action, which currently remains unclear. However, it is thought that it acts by modulating the functioning of the glutamatergic system, which plays an important role in the process of neuroplasticity associated with depression. However, preclinical and clinical studies have also found ketamine to reduce inflammation, either directly or indirectly (by activating neuroprotective branches of the kynurenine pathway), among patients exhibiting higher levels of inflammation. Inflammation and immune system activation are believed to play key roles in the development and course of depression. Therefore, the present work examines the role of the antidepressant effect of ketamine and its anti-inflammatory properties in the treatment of depression. SIGNIFICANCE STATEMENT: The present work examines the relationship between the antidepressant effect of ketamine and its anti-inflammatory properties, and the resulting benefits in treatment-resistant depression (TRD). The antidepressant mechanism of ketamine remains unclear, and there is an urgent need to develop new therapeutic strategies for treatment of depression, particularly TRD.

The role of CD38 in inflammation-induced depression-like behavior and the antidepressant effect of (R)-ketamine

CD38 is involved in immune responses, cell proliferation, and has been identified in the brain, where it is implicated in inflammation processes and psychiatric disorders. We hypothesized that dysfunctional CD38 activity in the brain may contribute to the pathogenesis of depression. To investigate the underlying mechanisms, we used a lipopolysaccharide (LPS)-induced depression-like model and conducted behavioral tests, molecular and morphological methods, along with optogenetic techniques. We microinjected adeno-associated virus into the hippocampal CA3 region with stereotaxic instrumentation. Our results showed a marked increase in CD38 expression in both the hippocampus and cortex of LPS-treated mice. Additionally, pharmacological inhibition and genetic knockout of CD38 effectively alleviated neuroinflammation, microglia activation, synaptic defects, and Sirt1/STAT3 signaling, subsequently improving depression-like behaviors. Moreover, optogenetic activation of glutamatergic neurons of hippocampal CA3 reduced the susceptibility of mice to depression-like behaviors, accompanied by reduced CD38 expression. We also found that (R)-ketamine, which displayed antidepressant effects, was linked to its anti-inflammatory properties by suppressing increased CD38 expression and reversing synaptic defects. In conclusion, hippocampal CD38 is closely linked to depression-like behaviors in an inflammation model, highlighting its potential as a therapeutic target for antidepressant development.

Tumour excisional surgery, anaesthetic-analgesic techniques, and oncologic outcomes: a narrative review

Cancer is a growing global burden; there were an estimated 18 million new cancer diagnoses worldwide in 2020. Excisional surgery remains one of the main treatments for solid organ tumours in cancer patients and is potentially curative. Cancer- and surgery-induced inflammatory processes can facilitate residual tumour cell survival, growth, and subsequent recurrence. However, it has been hypothesised that anaesthetic and analgesic techniques during surgery might influence the risk of cancer recurrence. This narrative review aims to provide an updated summary of recent observational studies and new randomised controlled clinical trials on whether certain specific anaesthetic and analgesic techniques or perioperative interventions during tumour resection surgery of curative intent materially affect long-term oncologic outcomes.

Anaesthesia in Veterinary Oncology: The Effects of Surgery, Volatile and Intravenous Anaesthetics on the Immune System and Tumour Spread

Throughout the course of oncological disease, the majority of patients require surgical, anaesthetic and analgesic intervention. However, during the perioperative period, anaesthetic agents and techniques, surgical tissue trauma, adjuvant drugs for local pain and inflammation and other non-pharmacological factors, such as blood transfusions, hydration, temperature and nutrition, may influence the prognosis of the disease. These factors significantly impact the oncologic patient's immune response, which is the primary barrier to tumour progress, promoting a window of vulnerability for its dissemination and recurrence. More research is required to ascertain which anaesthetics and techniques have immunoprotective and anti-tumour effects, which will contribute to developing novel anaesthetic strategies in veterinary medicine.

Effects of multimodal low-opioid anesthesia protocol during on-pump coronary artery bypass grafting: a prospective cohort study

BACKGROUND

The most favorable anesthesia protocol during on-pump coronary artery bypass grafting (CABG) in patients with coronary heart disease remains unclear, despite previous publications regarding the interaction between anesthesia protocol and postoperative complications. The aim of the study was to compare the effect of a multimodal low-opioid anesthesia protocol (MLOP) on early postoperative complications during on-pump CABG.

METHODS

A single-center prospective cohort study including 120 patients undergoing on-pump CABG aged 18 to 65 years, divided into two groups according to undergoing MLOP or routine-opioid anesthesia protocol (ROP). The analyzed parameters were plasma IL-6 levels, complications, duration of mechanical ventilation, length of intensive care unit stay, and hospitalization.

RESULTS

In the MLOP group, the levels of IL-6 at the end of the surgery were 25.6% significantly lower compared to the ROP group (33.4 ± 9.4 vs. 44.9 ± 15.9, p < 0.0001), the duration of mechanical ventilation was significantly shorter (2.0 (2.0; 3.0) h vs. 4.0 (3.0; 5.0) h, p < 0.001), the incidence of low cardiac output syndrome was almost two and half times lower (7 (11.7%) vs. 16 (26.7%), p = 0.037), and also the incidence of postoperative atrial fibrillation was significantly lower (9 (15.0%) vs. 19 (31.7%), p = 0.031).

CONCLUSION

Our study confirms that using MLOP was characterized by significantly lower levels of IL-6 at the end of surgery and a lower incidence of low cardiac output syndrome and postoperative atrial fibrillation than ROP.

TRIAL REGISTRATION

The study is registered in clinicaltrials.gov №NCT05514652.

Antidepressant mechanisms of ketamine: a review of actions with relevance to treatment-resistance and neuroprogression

Concurrent with recent insights into the neuroprogressive nature of depression, ketamine shows promise in interfering with several neuroprogressive factors, and has been suggested to reverse neuropathological patterns seen in depression. These insights come at a time of great need for novel approaches, as prevalence is rising and current treatment options remain inadequate for a large number of people. The rapidly growing literature on ketamine's antidepressant potential has yielded multiple proposed mechanisms of action, many of which have implications for recently elucidated aspects of depressive pathology. This review aims to provide the reader with an understanding of neuroprogressive aspects of depressive pathology and how ketamine is suggested to act on it. Literature was identified through PubMed and Google Scholar, and the reference lists of retrieved articles. When reviewing the evidence of depressive pathology, a picture emerges of four elements interacting with each other to facilitate progressive worsening, namely stress, inflammation, neurotoxicity and neurodegeneration. Ketamine acts on all of these levels of pathology, with rapid and potent reductions of depressive symptoms. Converging evidence suggests that ketamine works to increase stress resilience and reverse stress-induced dysfunction, modulate systemic inflammation and neuroinflammation, attenuate neurotoxic processes and glial dysfunction, and facilitate synaptogenesis rather than neurodegeneration. Still, much remains to be revealed about ketamine's antidepressant mechanisms of action, and research is lacking on the durability of effect. The findings discussed herein calls for more longitudinal approaches when determining efficacy and its relation to neuroprogressive factors, and could provide relevant considerations for clinical implementation.

Effects of anesthetic adjunctive agents on postoperative cognitive dysfunction in elderly patients undergoing noncardiac surgery: A Bayesian network meta-analysis

BACKGROUND

Elderly patients are prone to postoperative cognitive dysfunction (POCD). The comparison of the effects of anesthetic adjuvant drugs on POCD in elderly patients undergoing noncardiac surgery remains controversial.

METHODS

The final search took place on June 10, 2023. Randomized controlled trials including ketamine, ulinastatin, dexmedetomidine, parecoxib, and midazolam on the prevention and treatment of POCD in elderly undergoing noncardiac surgery were collected. A Bayesian network meta-analysis was performed to quantitatively combine the evidence.

RESULTS

A total of 35 randomized trials were finally included in this systematic review, and the overall risk of bias is Allocation concealment. These anesthetic adjuvant drugs did not show significant differences in preventing POCD on postoperative days 1 and 7 compared with each other, but ulinastatin may be more effective in preventing POCD than dexmedetomidine [odds ratio (OR) = 0.28, 95% confidence interval (CI) = (0.10, 0.71)] and parecoxib [OR = 0.3, 95% CI = (0.10, 0.82 on postoperative day 3. The efficiency ranking results also find that ulinastatin and ketamine might provide better effects regarding POCD prevention.

CONCLUSIONS

Ketamine and ulinastatin might have better effects in preventing POCD in elderly patients undergoing noncardiac surgery. Our meta-analysis provided evidence for the use of ulinastatin and ketamine in the prevention of POCD in elderly patients undergoing noncardiac surgery.

Rapamycin Augmentation of Chronic Ketamine as a Novel Treatment for Complex Regional Pain Syndrome

This case report describes the dramatic clinical response of refractory chronic complex regional pain syndrome to combined immunomodulatory treatment. Ketamine and rapamycin markedly minimized pain historically associated with suicidal behavior, increased baseline activity, and allowed for a reduction in palliative polypharmacy. The piecewise mechanism of action is unclear given multiple postulated targets, such as microglia, astroglia, T-regulatory cells, B-regulatory cells, or neurons. Relevant laboratory and genetic information may allow the application of this treatment to other affected individuals.

Inhibition of Microglial GSK3β Activity Is Common to Different Kinds of Antidepressants: A Proposal for an In Vitro Screen to Detect Novel Antidepressant Principles

Depression is a major public health concern. Unfortunately, the present antidepressants often are insufficiently effective, whilst the discovery of more effective antidepressants has been extremely sluggish. The objective of this review was to combine the literature on depression with the pharmacology of antidepressant compounds, in order to formulate a conceivable pathophysiological process, allowing proposals how to accelerate the discovery process. Risk factors for depression initiate an infection-like inflammation in the brain that involves activation microglial Toll-like receptors and glycogen synthase kinase-3β (GSK3β). GSK3β activity alters the balance between two competing transcription factors, the pro-inflammatory/pro-oxidative transcription factor NFκB and the neuroprotective, anti-inflammatory and anti-oxidative transcription factor NRF2. The antidepressant activity of tricyclic antidepressants is assumed to involve activation of GS-coupled microglial receptors, raising intracellular cAMP levels and activation of protein kinase A (PKA). PKA and similar kinases inhibit the enzyme activity of GSK3β. Experimental antidepressant principles, including cannabinoid receptor-2 activation, opioid μ receptor agonists, 5HT2 agonists, valproate, ketamine and electrical stimulation of the Vagus nerve, all activate microglial pathways that result in GSK3β-inhibition. An in vitro screen for NRF2-activation in microglial cells with TLR-activated GSK3β activity, might therefore lead to the detection of totally novel antidepressant principles with, hopefully, an improved therapeutic efficacy.

Administration of ketamine/xylazine increases severity of influenza (A/Puerto Rico/8/34) in mice

The use of ketamine/xylazine for its anesthetic, anti-inflammatory, and anti-depressant properties could alter other medications and immune functions of the body. Thus, the current study explored how ketamine/xylazine affects the severity of influenza infection in BALB/c and C57Bl/6 mice, monitored for weight loss after intranasal inoculation with A/Puerto Rico/8/34 influenza virus. Mice were inoculated by using a micropipettor to insert 18 μL of control or a suspension of virus into each nostril and allowing the mouse to inhale the material. Several experiments were performed where groups of mice were treated with various combinations of virus and anesthesia and the results compared. Mice were weighed daily and monitored for other signs of illness. The experiments continued until the mice either regained their original weight or died (were euthanized when signs indicated non-recoverable status), which ranged from nine to twenty-three days. Anesthetized mice experienced more weight loss. Additionally, in experiments where the virus suspension was potent enough to lead to death, only mice that were anesthetized died.

Role of the mesolimbic dopamine pathway in the antidepressant effects of ketamine

Depression is a complex and highly heterogeneous disorder which diagnosis is based on an exceedingly variable set of clinical symptoms. Current treatments focus almost exclusively on the manipulation of monoamine neurotransmitter systems, but despite considerable efforts, these remain inadequate for a significant proportion of those afflicted by the disorder. The emergence of racemic (R, S)-ketamine as a fast-acting antidepressant has provided an exciting new path for the study of major depressive disorder (MDD) and the search for better therapeutics for its treatment. Previous work suggested that ketamine's mechanism of action is primarily mediated via blockaded of N-methyl-d-aspartate (NMDA) receptors, however, this is an area of active research and clinical and preclinical evidence now indicate that ketamine acts on multiple systems. The last couple of decades have cemented the mesolimbic dopamine reward pathway's involvement in the pathogenesis of MDD and related mood disorders. Exposure to negative stress dysregulates dopamine neuronal activity disrupting reward and motivational processes resulting in anhedonia (lack of pleasure), a hallmark symptom of depression. Although the mechanism(s) underlying ketamine's antidepressant activity continue to be elucidated, current evidence indicate that its therapeutic effects are mediated, at least in part, via long-lasting synaptic changes and subsequent molecular adaptations in brain regions within the mesolimbic dopamine system. Notwithstanding, ketamine is a drug of abuse, and this liability may pose limitations for long term use as an antidepressant. This review outlines the current knowledge of ketamine's actions within the mesolimbic dopamine system and its abuse potential. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

Long-term effect of anesthesia choice on patients with hepatocellular carcinoma undergoing open liver resection

Clinical and experimental evidence suggested that anesthesia choice can influence cancer progression and patients' outcomes by modulating tumor microenvironment and tumorigenic pathways. Curative resection is the mainstay of therapy for hepatocellular carcinoma (HCC), which is an intractable disease due to high recurrence and poor prognosis. However, different anesthetics may play different roles in alleviating surgery-induced stress response and inflammatory cytokines release that are considered to be closely associated with proliferation, invasion and metastasis of tumor cells. Propofol, sevoflurane, non-steroidal anti-inflammatory drugs and local anesthetics have shown to exert anti-tumor effect on HCC mainly through regulating microRNAs or signaling pathways, while other inhalational agents, dexmedetomidine and opioids have the potential to promote tumor growth. In terms of anesthetic methods and analgesia strategies, propofol based total intravenous anesthesia and thoracic epidural analgesia could be preferred for HCC patients undergoing open liver resection rather than inhalational anesthesia. Local anesthesia techniques have great potential to attenuate perioperative stress response, hence they may contribute to more favorable outcomes. This review summarized the relations between different anesthesia choices and HCC patients' long-term outcomes as well as their underlying mechanisms. Due to the complexity of molecules interactions and signaling pathways, further studies are warranted to confirm these results so as to optimize anesthesia strategy for HCC patients.

Influence of Perioperative Anesthesia on Cancer Recurrence: from Basic Science to Clinical Practice

PURPOSEOF REVIEW

In this review, we will summarize the effects of these perioperative anesthetics and anesthetic interventions on the immune system and tumorigenesis as well as address the related clinical evidence on cancer-related mortality and recurrence.

RECENT FINDINGS

Cancer remains a leading cause of morbidity and mortality worldwide. For many solid tumors, surgery is one of the major therapies. Unfortunately, surgery promotes angiogenesis, shedding of circulating cancer cells, and suppresses immunity. Hence, the perioperative period has a close relationship with cancer metastases or recurrence. In the perioperative period, patients require multiple anesthetic management including anesthetics, anesthetic techniques, and body temperature control. Preclinical and retrospective studies have found that these anesthetic agents and interventions have complex effects on cancer outcomes. Therefore, well-planned, prospective, randomized controlled trials are required to explore the effects of different anesthetics and techniques on long-term outcomes after cancer surgery. Due to the conflicting effects of anesthetic management on cancer recurrence, further preclinical and clinical trials are required and beneficial to the development of systemic cancer therapies.

A Pre-Clinical Study of Sub-Anesthetic Ketamine as Remedy in 5-Fluorouracil-Induced Cachexia Model

Around 0.5-1% of the world population is suffering from cachexia. In particular, cancer patients under cancer radio-chemotherapy have a high prevalence of cachexia, especially during the end stages of therapeutic treatment. Clinically, chemotherapeutic 5-fluorouracil (5-Fu) treatment often leads to the development of adverse effects, such as leukopenia, immune dysfunction, anorexia, muscle wasting, etc., and 5-Fu also tends to exacerbate the occurrence of cancer cachexia. Currently, there are very limited drug choices when seeking to revive cachexia patient's health quality while enduring a full therapeutic regimen as part of advanced cancer therapy. The present study employed chemotherapeutic drug 5-Fu-induced cachexia-like conditions in Balb/c mice. After 8 days of 5-Fu treatment, mice had begun to show cachexia-like symptoms such as weight loss and reduced food intake. After one day of washing out, the cachexia animals received a single dose of either saline solution as a mock dose or a low dose (15 mg/kg BW) or high dose (30 mg/kg BW) of ketamine at day 10. For the following 7 days, food intake, body weight, and mortality were monitored. Data were analyzed with the LOCF (last observation carried forward) method. Improved survival rates were obtained in ketamine groups. Ketamine administration at the high dose of 30 mg/kg BW demonstrated effectively diminished weight loss due to cachexia, and also successfully improved overall survival. The current study demonstrates that a sub-anesthetic level of ketamine administration supports overall beneficial outcomes in 5-Fu-induced cachexia and outlook as a potential clinical remedy.

Safety of general anaesthetics on the developing brain: are we there yet?

Thirty years ago, neurotoxicity induced by general anaesthetics in the developing brain of rodents was observed. In both laboratory-based and clinical studies, many conflicting results have been published over the years, with initial data confirming both histopathological and neurodevelopmental deleterious effects after exposure to general anaesthetics. In more recent years, animal studies using non-human primates and new human cohorts have identified some specific deleterious effects on neurocognition. A clearer pattern of neurotoxicity seems connected to exposure to repeated general anaesthesia. The biochemistry involved in this neurotoxicity has been explored, showing differential effects of anaesthetic drugs between the developing and developed brains. In this narrative review, we start with a comprehensive description of the initial concerning results that led to recommend that any non-essential surgery should be postponed after the age of 3 yr and that research into this subject should be stepped up. We then focus on the neurophysiology of the developing brain under general anaesthesia, explore the biochemistry of the observed neurotoxicity, before summarising the main scientific and clinical reports investigating this issue. We finally discuss the GAS trial, the importance of its results, and some potential limitations that should not undermine their clinical relevance. We finally suggest some key points that could be shared with parents, and a potential research path to investigate the biochemical effects of general anaesthesia, opening up perspectives to understand the neurocognitive effects of repetitive exposures, especially in at-risk children.

Immunological Insights into Opioid-Free Anaesthesia in Oncological Surgery: A Scoping Review

Purpose of Review

The influence of opioids on outcomes after cancer surgery when used, or avoided, intraoperatively remains unclear. There is a need to conduct a scoping review to explore the wider context and provide direction for future research. The review will examine the current state of evidence in humans, with a focus on immunological biomarkers and clinically relevant cancer outcomes in trials comparing opioid-free to opioid-based general anaesthesia.

Recent Findings

There is limited research on this subject area, which is mainly focused on breast cancer. The most frequently evaluated immunological parameter is the neutrophil-to-lymphocyte ratio. Cancer outcomes are mainly focused on recurrence.

Summary

The central knowledge gap is understanding how the cellular effects of opioids translate into longer-term patient outcomes. The major challenge for future research is accounting for the immunomodulatory effects of a wide range of confounding factors, which have yet to be clarified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11912-022-01300-5.

Ketamine Does Not Change Natural Killer Cell Cytotoxicity in Patients Undergoing Cancer Surgery: Basic Experiment and Clinical Trial

Background. The natural killer cell cytotoxicity (NKCC) suppressed by nociceptive stimuli, systemic inflammation, and drugs used during cancer surgery may be associated with poor outcomes. We investigated the potential modulation of ketamine on NKCC in vitro and in a clinical setting during cancer surgery. Subjects and Methods. The NK cell line KHYG1 was cultured for the in vitro experiments. The NK cells were treated with 3 and 10 μM ketamine (the ketamine groups) or without ketamine (the control) for 4, 24, and 48 h. The posttreatment NKCC was measured with a lactate dehydrogenase assay and compared among the treatment groups. For the clinical study, lung cancer patients ( $n=38$ ) and prostate cancer patients ( $n=60$ ) who underwent radical cancer surgeries at a teaching hospital were recruited. The patients received propofol and remifentanil superposed with or without ketamine (ketamine group, $n=47$ ; control group, $n=51$ ). The primary outcome was the difference in NKCC between these groups. Results. In the in vitro experiment, the cytotoxicity of NK cells was similar with or without ketamine at all of the incubation periods. The patients’ NKCC was also not significantly different between the patients who received ketamine and those who did not, at the baseline ( $36.6\pm 16.7$ % vs. $38.5\pm 15.4$ %, $p=0.56$ ) and at 24 h ( $25.6\pm 12.9$ % vs. $27.7\pm 13.5$ %, respectively, $p=0.49$ ). Conclusion. Ketamine does not change NKCC in vitro or in the clinical setting of patients who undergo cancer surgery. This trial is registered with UMIN000021231.

Effects of an intravenous ketamine infusion on inflammatory cytokine levels in male and female Sprague-Dawley rats

Background

Ketamine, a multimodal dissociative anesthetic drug, is widely used as an analgesic following traumatic injury. Although ketamine may produce anti-inflammatory effects when administered after injury, the immunomodulatory properties of intravenous (IV) ketamine in a non-inflammatory condition are unclear. In addition, most preclinical studies use an intraperitoneal (IP) injection of ketamine, which limits its clinical translation as patients usually receive an IV ketamine infusion after injury.

Methods

Here, we administered sub-anesthetic doses of a single IV ketamine infusion (0, 10, or 40 mg/kg) to male and female Sprague–Dawley rats over a 2-h period. We collected blood samples at 2- and 4-h post-ketamine infusion to determine plasma inflammatory cytokine levels using multiplex immunoassays.

Results

The 10 mg/kg ketamine infusion reduced spontaneous locomotor activity in male and female rats, while the 40 mg/kg infusion stimulated activity in female, but not male, rats. The IV ketamine infusion produced dose-dependent and sex-specific effects on plasma inflammatory cytokine levels. A ketamine infusion reduced KC/GRO and tumor necrosis factor alpha (TNF-α) levels in both male and female rats, interleukin-6 (IL-6) levels in female rats, and interleukin-10 (IL-10) levels in male rats. However, most cytokine levels returned to control levels at 4-h post-infusion, except for IL-6 levels in male rats and TNF-α levels in female rats, indicating a different trajectory of certain cytokine changes over time following ketamine administration.

Conclusions

The current findings suggest that sub-anesthetic doses of an IV ketamine infusion may produce sex-related differences in the effects on peripheral inflammatory markers in rodents, and further research is warranted to determine potential therapeutic effects of an IV ketamine infusion in an inflammatory condition.

Ketamine as a therapeutic agent for depression and pain: mechanisms and evidence

Ketamine is an anesthetic drug which is now used to treat chronic pain conditions and psychiatric disorders, especially depression. It is an N-methyl-D-aspartate (NMDA) receptor antagonist with additional effects on α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, opioid receptors, and monoaminergic receptors. This article focuses on ketamine's role in treating depression and pain, two commonly comorbid challenging conditions with potentially shared neurobiologic circuitry. Many clinical trials have utilized intravenous or intranasal ketamine for treating depression and pain. Intravenous ketamine is more bioavailable than intranasal ketamine and both are effective for acute depressive episodes. Intravenous ketamine is advantageous for post-operative analgesia and is associated with a reduction in total opioid requirements. Few studies have treated chronic pain or concurrent depression and pain with ketamine. Larger, randomized control trials are needed to examine the safety and efficacy of intravenous vs. intranasal ketamine, ideal target populations, and optimal dosing to treat both depression and pain.

Ketamine inhibits TNF-α-induced cecal damage by enhancing RIP1 ubiquitination to attenuate lethal SIRS

Systemic inflammatory response syndrome (SIRS) is a sepsis-associated inflammatory state and a self-defense mechanism against specific and nonspecific stimuli. Ketamine influences many key processes that are altered during sepsis. However, the underlying mechanisms remain incompletely understood. In this study, TNF-α-treated mice, as well as HT-29 and L929 cell models, were applied to characterize TNF-α-induced systemic and local cecal tissue inflammatory responses. Behavioral, biochemical, histological, and molecular biological approaches were applied to illustrate the related processes. Mice with TNF-α-induced SIRS showed systemic and local cecal tissue inflammatory responses, as indicated by increased levels of high mobility group box 1 protein (HMGB1), chemokines (C-X-C motif) ligand 10 (CXCL10), interleukin-6 (IL-6), and IL-10, as well as high mortality. Ketamine pretreatment alleviated death rates, symptoms, and the production of inflammatory cytokines induced by TNF-α in mice. Moreover, ketamine also protected the mice from TNF-α-induced cecal damage by suppressing the phosphorylation of receptor-interacting serine/threonine-protein kinase 3 (RIP3) and mixed lineage kinase domain-like protein (MLKL). In addition, our results showed that ketamine efficiently inhibited TNF-α-induced necroptosis in HT-29 and L929 cells. Furthermore, we explored the mechanism using different L929 cell lines. The results displayed that ketamine inhibited TNF-α-induced necroptosis by enhancing RIP1 ubiquitination and reducing the RIP1-RIP3 and RIP3-MLKL interactions, as well as the formation of necrosomes. Thus, our study may provide a new theoretical and experimental basis for treating diseases characterized by SIRS-associated inflammatory factor storms. Moreover, our exploration may provide potential molecular mechanisms and targets for therapeutic intervention and clinical application of ketamine.

Can Acute Postoperative Pain Management After Tumour Resection Surgery Modulate Risk of Later Recurrence or Metastasis?

Background

Cancer is a leading cause of mortality worldwide, but death is rarely from the primary tumour: Rather it is multi-organ dysfunction from metastatic disease that is responsible for up to 90% of cancer-related deaths. Surgical resection of the primary tumour is indicated in 70% of cases. The perioperative stress response, tissue hypoxia at the site of surgery, and acute pain contribute to immunosuppression and neo-angiogenesis, potentially promoting tumour survival, proliferation, and metastasis. Poorly controlled acute postoperative pain decreases Natural Killer (NK) immune cell activity, which could potentially facilitate circulating tumour cells from evading immune detection. This consequently promotes tumour growth and distal metastasis.

Methods

We conducted a comprehensive literature search for links between acute pain and cancer outcomes using multiple online databases. Relevant articles from January 1st, 2010 to September 1st, 2021 were analysed and appraised on whether postoperative pain control can modulate the risk of recurrence, metastasis, and overall cancer survival.

Results

Although experimental and retrospective clinical data suggest a plausible role for regional anaesthesia in cancer outcome modulation, this has not been supported by the single, largest prospective trial to date concerning breast cancer. While there are mixed results on anaesthesiology drug-related interventions, the most plausible data relates to total intravenous anaesthesia with propofol, and to systemic administration of lidocaine.

Conclusion

The hypothesis that anaesthetic and analgesic technique during cancer surgery could influence risk of subsequent recurrence or metastasis has been prevalent for >15 years. The first, large-scale definitive trial among women with breast cancer found robust equivalent findings between volatile anaesthesia with opioid analgesia and regional anaesthesia. Therefore, while regional anaesthesia during tumour resection does not seem to have any effect on cancer outcomes, it remains plausible that other anaesthetic techniques (e.g. total intravenous anaesthesia and systemic lidocaine infusion) might influence oncologic outcome in other major tumour resection surgery (e.g. colorectal and lung). Therefore, another large trial is needed to definitively answer these specific research questions. Until such evidence is available, perioperative analgesia for cancer surgery of curative intent should be based on patient co-morbidity and non-cancer endpoints, such as optimising analgesia and minimising postoperative complications.

Targeting inflammation in depression: Ketamine as an anti-inflammatory antidepressant in psychiatric emergency

Major depressive disorder (MDD) is a common psychiatric disorder with multifactorial aetiology and complex pathophysiology. Despite availability of various pharmacological and non-pharmacological therapeutic strategies, treatment resistant depression (TRD) remains a significant challenge with specific concern for those patients with severe depressive symptoms in particular suicidal ideations who require immediate and effective intervention. Inflammation has been widely studied for its association with MDD and treatment response. Ketamine known as a dissociative anaesthetic has a novel rapid-acting antidepressant effect at lower doses. Anti-inflammatory actions of ketamine appear to play a role in mechanisms underlying its antidepressant effects. Considering the rapid antidepressant action of ketamine, this review provides a brief overview of antidepressant properties of ketamine as well as its effects on peripheral and central inflammation to better understand the mechanisms underlying the therapeutic action of ketamine as an anti-inflammatory antidepressant target in psychiatric emergency. Development of effective medications, which act rapidly with dual effect on both inflammation and MDD would be of a significant clinical importance for a successful and personalised treatment of inflammatory-induced TRD and suicidal thoughts and behaviour.

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Anti-inflammatory actions of ketamine play a role in mechanisms underlying its antidepressant effects.

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Ketamine’s dual effect on inflammation and depression is particularly important in treatment of inflammatory-induced TRD and suicidal patients.

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Ketamine affects CNS receptors and pathways, neurotransmitter systems, synaptogenesis, and inflammatory responses.

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Ketamine remains a promising target for treatment of TRD and suicidal thoughts.

The hypoxic pulmonary vasoconstriction: From physiology to clinical application in thoracic surgery

More than 70 years after its original report, the hypoxic pulmonary vasoconstriction (HPV) response continues to spark scientific interest on its mechanisms and clinical implications, particularly for anesthesiologists involved in thoracic surgery. Selective airway intubation and one-lung ventilation (OLV) facilitates the surgical intervention on a collapsed lung while the HPV redirects blood flow from the "upper" non-ventilated hypoxic lung to the "dependent" ventilated lung. Therefore, by limiting intrapulmonary shunting and optimizing ventilation-to-perfusion (V/Q) ratio, the fall in arterial oxygen pressure (PaO₂) is attenuated during OLV. The HPV involves a biphasic response mobilizing calcium within pulmonary vascular smooth muscles, which is activated within seconds after exposure to low alveolar oxygen pressure and that gradually disappears upon re-oxygenation. Many factors including acid-base balance, the degree of lung expansion, circulatory volemia as well as lung diseases and patient age affect HPV. Anesthetic agents, analgesics and cardiovascular medications may also interfer with HPV during the perioperative period. Since HPV represents the homeostatic mechanism for regional ventilation-to-perfusion matching and in turn, for optimal pulmonary oxygen uptake, a clear understanding of HPV is clinically relevant for all anesthesiologists.

The Effects of Anesthetics and Perioperative Medications on Immune Function: A Narrative Review

Preclinical and clinical studies have sought to better understand the effect of anesthetic agents, both volatile and intravenous, and perioperative adjuvant medications on immune function. The immune system has evolved to incorporate both innate and adaptive components, which are delicately interwoven and essential for host defense from pathogens and malignancy. This review summarizes the complex and nuanced relationship that exists between each anesthetic agent or perioperative adjuvant medication studied and innate and adaptive immune function with resultant clinical implications. The most commonly used anesthetic agents were chosen for review including volatile agents (sevoflurane, isoflurane, desflurane, and halothane), intravenous agents (propofol, ketamine, etomidate, and dexmedetomidine), and perioperative adjuvant medications (benzodiazepines, opioids, nonsteroidal anti-inflammatory drugs [NSAIDs], and local anesthetic agents). Patients who undergo surgery experience varying combinations of the aforementioned anesthetic agents and adjuncts, depending on the type of surgery and their comorbidities. Each has unique effects on immunity, which may be more or less ideal depending on the clinical situation. Further study is needed to better understand the clinical effects of these relationships so that patient-specific strategies can be developed to improve surgical outcomes.

Anesthetics or anesthetic techniques and cancer surgical outcomes: a possible link

As of 2018 cancer is responsible for almost 9.6 million deaths annually and, with an aging population, the incidence of cancer is expected to continue to rise. Surgery is an important treatment modality for patients with solid organ cancers. It has been postulated that, due to potentially overlapping processes underlying the development of malignancy and the therapeutic pathways of various anesthetic agents, the choice of anesthetic type and method of administration may affect post-operative outcomes in patients with cancer. This is a literature review of the most recent evidence extracted from various databases including PubMed, EMBASE, and the Cochrane, as well as journals and book reference lists. The review highlights the pathophysiological processes underpinning cancer development and the molecular actions of anesthetic agents, pre-clinical and retrospective studies investigating cancer and anesthetics, as well as ongoing clinical trials. Overall, there are conflicting results regarding the impact of regional vs. general anesthesia on cancer recurrence, whilst the majority of data suggest a benefit of the use of intravenous propofol over inhalational volatile anesthetics. The biological changes associated with the surgical inflammatory response offer a unique opportunity to intervene to counteract any potentially cancer-promoting effects.

Neuroimmunology of depression

Depression is one of the leading causes of disability worldwide and a major contributor to the global burden of disease, yet the cellular and molecular etiology of depression remain largely unknown. Major Depressive Disorder (MDD) is associated with a variety of chronic physical inflammatory and autoimmune disorders, and mood disorders may act synergistically with other medical disorders to worsen patient outcomes. Here, we outline the neuroimmune complement, explore the evidence for altered immune system function in MDD, and present some of the potential mechanisms by which immune cells and molecules may drive the onset and course of MDD. These include pro-inflammatory signaling, alterations in the hypothalamic-pituitary-adrenal axis, dysregulation of the serotonergic and noradrenergic neurotransmitter systems, neuroinflammation, and meningeal immune dysfunction. Finally, we discuss the interactions between current antidepressants and the immune system and propose the possibility of immunomodulatory drugs as potential novel antidepressant treatments.

Neuroprotective effect of ketamine against TNF-α-induced necroptosis in hippocampal neurons

Tumour necrosis factor‐α (TNF‐α), a crucial cytokine, has various homeostatic and pathogenic bioactivities. The aim of this study was to assess the neuroprotective effect of ketamine against TNF‐α‐induced motor dysfunction and neuronal necroptosis in male C57BL/6J mice in vivo and HT‐22 cell lines in vitro. The behavioural testing results of the present study indicate that ketamine ameliorated TNF‐α‐induced neurological dysfunction. Moreover, immunohistochemical staining results showed that TNF‐α‐induced brain dysfunction was caused by necroptosis and microglial activation, which could be attenuated by ketamine pre‐treatment inhibiting reactive oxygen species production and mixed lineage kinase domain‐like phosphorylation in hippocampal neurons. Therefore, we concluded that ketamine may have neuroprotective effects as a potent inhibitor of necroptosis, which provides a new theoretical and experimental basis for the application of ketamine in TNF‐α‐induced necroptosis‐associated diseases.

The immunomodulatory effect of ketamine in colorectal cancer surgery: a randomized-controlled trial

PURPOSE

Ketamine's inhibitory action on the N-methyl-D-aspartate receptor and anti-inflammatory effects may provide beneficial immunomodulation in cancer surgery. We investigated the effect of subanesthetic-dose ketamine as an adjunct to desflurane anesthesia on natural killer (NK) cell activity and inflammation in patients undergoing colorectal cancer surgery.

METHODS

A total of 100 patients were randomly assigned to a control or ketamine group. The ketamine group received a bolus of 0.25 mg·kg^-1 ketamine five minutes before the start of surgery, followed by an infusion 0.05 mg·kg^-1·hr^-1 until the end of surgery; the control group received a similar amount of normal saline. We measured NK cell activity and proinflammatory cytokines (interleukin-6 [IL-6] and tumour necrosis factor-α [TNF-α]) before surgery and one, 24, and 48 hr after surgery. C-reactive protein (CRP) was measured before surgery and one, three, and five days after surgery. Carcinoembryonic antigen and cancer recurrence/metastasis were assessed two years after surgery.

RESULTS

The NK cell activity was significantly decreased after surgery in both groups, but the change was not different between groups in the linear mixed model analysis (P = 0.47). Changes in IL-6, TNF-α, CRP, and carcinoembryonic antigen levels were not different between groups (P = 0.27, 0.69, 0.99, and 0.97, respectively). Cancer recurrence within 2 years after surgery was similar between groups (10% vs 8%, P = 0.62).

CONCLUSIONS

Intraoperative low-dose ketamine administration did not convey any favourable impacts on overall postoperative NK cell activity, inflammatory responses, and prognosis in colorectal cancer surgery patients.

TRIAL REGISTRATION

www.clinicaltrial.gov (NCT03273231); registered 6 September 2017.

A Critical Appraisal of the Effects of Anesthetics on Immune-system Modulation in Critically Ill Patients With COVID-19

Purpose

The aim of the present article was to briefly summarize current knowledge about the immunomodulatory effects of general anesthetics and the possible clinical effects of this immunomodulation in patients with COVID-19.

Methods

The PubMed, Scopus, and Google Scholar databases were comprehensively searched for relevant studies.

Findings

The novel coronavirus causes a wide spectrum of clinical manifestations, with a large absolute number of patients experiencing severe pneumonia and rapid progression to acute respiratory distress syndrome and multiple organ failure. In these patients, the equilibrium of the inflammatory response is a major determinant of survival. The impact of anesthetics on immune-system modulation may vary and includes both pro-inflammatory and anti-inflammatory effects.

Implications

Inhibition of the development of severe inflammation and/or the enhancement of inflammation resolution by anesthetics may limit organ damage and improve outcomes in patients with COVID-19.

A review of the clinical applications of ketamine in pediatric oncology

Ketamine is a dissociative anesthetic agent with excellent analgesic properties and a favorable safety profile. The feasibility and efficacy of various routes of administration have been established, including intravenous (IV), intramuscular (IM), oral, intranasal, rectal, and transdermal routes. The advent of newer anesthetic agents has led to a decline in the use of ketamine as an anesthetic, but its utility in short-term sedation and analgesia has expanded. Its value for chronic pain management in children with cancer is being increasingly recognized but requires more evidence. The use of topical ketamine is largely in investigational stages. Medical use of ketamine is, to a great extent, free from significant long-term neurological side effects. The objective of this review is to provide a brief account of the pharmacology of ketamine and primarily focus on the clinical applications of ketamine in pediatric oncology.

Which idea is better with regard to immune response? Opioid anesthesia or opioid free anesthesia

The stress of surgery is characterized by an inflammatory response with immune suppression resulting from many factors, including the type of surgery and the kind of anesthesia, linked with the drugs that are used and the underlying disease of the patient. The trauma of surgery triggers a cascade of reactions involving the immune response and nociception. As strong analgesics, opioids provide the analgesic component of general anesthesia with bi-directional effect on the immune system. Opioids influence almost all aspects of the immune response in regards to leukocytes, macrophages, mast cells, lymphocytes, and NK cells. The suppressive effect of opioids on the immune system is limiting their use, especially in patients with impaired immune response, so the possibility of using multimodal anesthesia without opioids, known as opioid-free anesthesia (OFA), is gaining more and more sympathizers. The idea of OFA is to eliminate opioid analgesia in the treatment of acute pain and to replace it with drugs from other groups that are assumed to have a comparable analgesic effect without affecting the immune system. Here, we present a review on the impact of anesthesia, with and without the use of opioids, on the immune response to surgical stress.

Immunomodulation by ketamine as an adjunct to total intravenous anesthesia in patients undergoing minimally invasive radical prostatectomy: A randomized pilot trial

Post-surgery immunomodulation, including reduced natural killer cell cytotoxicity (NKCC), is recognized as a predictor of poor outcomes in patients following cancer surgery. The present study investigated direct immunomodulation via ketamine as an anesthetic adjuvant in patients undergoing cancer surgery. The present non-double blinded randomized trial was conducted at Hirosaki University Hospital with 60 patients who underwent minimally invasive robotic radical prostatectomy to minimize the immunomodulation due to surgical stress. Patients received total intravenous anesthesia using propofol and remifentanil, with ketamine as an anesthetic adjuvant (the ketamine group) or without ketamine (the control group). The primary outcome was the difference in NKCC between these groups. The secondary outcomes were the differences in neutrophil-lymphocyte ratio (NLR) and levels of interleukin (IL)-6, IL-1β, IL-10 and tumor necrosis factor-alpha (TNF-α). NKCC and cytokines were measured before anesthesia (baseline) and at 6 and 24 h after baseline measurements were recorded. NLR was determined on the last day before admission and at 48 h post-baseline. NKCC values were similar in each group at 6 h when compared with respective baseline results (baseline control, 36.9±15.6%; 6 h control, 38.3±13.4%; baseline ketamine, 36.1±17.0%; 6 h ketamine, 36.6±16.4%) but significantly decreased at 24 h (control, 26.5±12.2%; ketamine, 24.1±12.7%; P<0.001). There were no significant differences in NKCC between the ketamine and control groups (P=0.64) at any of the assessed time points. NLR, IL-1β, IL-10 and TNF-α levels were also similar between two groups. In contrast, IL-6 at 24 h was significantly lower in the ketamine group compared with the control group (mean difference, -7.3 pg ml^-1; 95% confidence interval, -14.4 to -0.2; P=0.04). Ketamine as an anesthetic adjuvant did not provide direct immunomodulation in patients who underwent cancer surgery.

Ketamine Blocks Morphine-Induced Conditioned Place Preference and Anxiety-Like Behaviors in Mice

Patients suffering from opioid use disorder often relapse during periods of abstinence, which is posited to be caused by negative affective states that drive motivated behaviors. Here, we explored whether conditioning mice with morphine in a conditioned place preference (CPP) training paradigm evoked anxiety-like behavior during morphine abstinence. To do this, mice were conditioned with morphine (10 mg/kg, i.p.) for 5 days. Twenty-four hours following conditioning, anxiety levels were tested by measuring time in the open arms of the elevated plus-maze. The next day, mice were placed in the three-compartment chamber to measure morphine-induced CPP. Our results show that following morphine conditioning, mice spent significantly less time in the open arm of the elevated plus-maze and expressed robust morphine CPP on CPP test day. Furthermore, we found that an acute treatment with (R,S)-ketamine (10 mg/kg, i.p.), a medication demonstrating promise for preventing anxiety-related phenotypes, 30 min before testing on post-conditioning day 1, increased time spent in the open arm of the elevated plus-maze in saline- and morphine-conditioned mice. Additionally, we found that the second injection of ketamine 30 min before CPP tests on post-conditioning day 2 prevented morphine-induced CPP, which lasted for up to 28 days post-conditioning. Furthermore, we found that conditioning mice with 10% (w/v) sucrose using an oral self-administration procedure did not evoke anxiety-like behavior, but elicited robust CPP, which was attenuated by ketamine treatment 30 min before CPP tests. Overall, our results suggest that the ketamine-induced block of morphine CPP may not be attributed solely to alleviating negative affective states, but potentially through impaired memory of morphine-context associations.

Impact of perioperative pain management on cancer recurrence: an ASRA/ESRA special article

Cancer causes considerable suffering and 80% of advanced cancer patients experience moderate to severe pain. Surgical tumor excision remains a cornerstone of primary cancer treatment, but is also recognized as one of the greatest risk factors for metastatic spread. The perioperative period, characterized by the surgical stress response, pharmacologic-induced angiogenesis, and immunomodulation results in a physiologic environment that supports tumor spread and distant reimplantation.In the perioperative period, anesthesiologists may have a brief and uniquewindow of opportunity to modulate the unwanted consequences of the stressresponse on the immune system and minimize residual disease. This reviewdiscusses the current research on analgesic therapies and their impact ondisease progression, followed by an evidence-based evaluation of perioperativepain interventions and medications.

Endometriosis and pain in the adolescent- striking early to limit suffering: A narrative review

Endometriosis, a condition in which uterine tissue grows outside the uterus, is a debilitating disease, affecting millions of women and costing the United States approximately $78 billion annually in pain- related disability. It is also the leading cause of chronic pelvic pain (CPP), which is often unresponsive to existing treatments. Adolescent women with the disease are at particular risk as there are often significant diagnostic delays, which in turn can exacerbate pain. Research and treatment guidelines for adolescents with endometriosis are largely based on studies for adult women due to the limited number of studies focusing on adolescents. The current paper critically reviews the literature as it pertains to endometriosis pathophysiology, mechanisms contributing to CPP, and treatment implications and recommendations with a focus on gaps related to adolescents.

Microglial production of quinolinic acid as a target and a biomarker of the antidepressant effect of ketamine

Major depressive disorder is a complex multifactorial condition with a so far poorly characterized underlying pathophysiology. Consequently, the available treatments are far from satisfactory as it is estimated that up to 30% of patients are resistant to conventional treatment. Recent comprehensive evidence has been accumulated which suggests that inflammation may be implied in the etiology of this disease. Here we investigated ketamine as an innovative treatment strategy due to its immune-modulating capacities. In a murine model of LPS-induced depressive-like behavior we demonstrated that a single dose of ketamine restores the LPS-induced depressive-like alterations. These behavioral effects are associated with i/ a reversal of anxiety and reduced self-care, ii/ a decrease in parenchymal cytokine production, iii/ a modulation of the microglial reactivity and iv/ a decrease in microglial quinolinic acid production that is correlated with plasmatic peripheral production. In a translational approach, we show that kynurenic acid to quinolinic acid ratio is a predictor of ketamine response in treatment-resistant depressed patients and that the reduction in quinolinic acid after a ketamine infusion is a predictor of the reduction in MADRS score. Our results suggest that microglia is a key therapeutic target and that quinolinic acid is a biomarker of ketamine response in major depressive disorder.

Ketamine applications beyond anesthesia - A literature review

Ketamine's clinical use began in the 1970s. Physicians benefited from its safety and ability to induce short-term anesthesia and analgesia. The psychodysleptic effects caused by the drug called its further clinical use into question. Despite these unpleasant effects, ketamine is still applied in veterinary medicine, field medicine, and specialist anesthesia. Recent intensive research brought into light new possible applications of this drug. It began to be used in acute, chronic and cancer pain management. Most interesting reports come from research on the antidepressive and antisuicidal properties of ketamine giving hope for the creation of an effective treatment for major depressive disorder. Other reports highlight the possible use of ketamine in treating addiction, asthma and preventing cancer growth. Besides clinical use, the drug is also applied to in animal model of schizophrenia. It seems that nowadays, with numerous possible applications, the use of ketamine has returned; to its former glory. Nevertheless, the drug must be used with caution because still the mechanisms by which it executes its functions and long-term effects of its use are not fully known. This review aims to discuss the well-known and new promising applications of ketamine.

The Influence of Antidepressants on the Immune System

Depression is one of the most frequently diagnosed condition in psychiatry. Despite the availability of many preparations, over 30% of treated patients do not achieve remission. Recently the emphasis is put on the contribution of the body’s inflammatory response as one of the causes of depression. The interactions between nervous and immune systems are the main issue addressed by psychoneuroimmunology. In patients suffering from depression changes in the plasma concentrations of cytokines and in the number and level of activation of immune cells has been found. Attention is paid to the high levels of pro-inflammatory cytokines, the prevalence of Th1 responses to Th2, weakening of NK cell cytotoxicity and changes in lymphocyte proliferation and apoptosis. A number of studies focus on influence of antidepressants and non-standard methods of depression treatment, such as ketamine infusion, on patients’ immunology. Many of them seem to regulate the immune responses. The study results encourage to look for new ways to treat depression with immunomodulatory drugs. In this article authors present the current knowledge about immune system changes accompanying depression as well as the study results showing the influence of drugs on the immune system, especially in the context of reducing the symptoms of depression.

Effects of Perinatal Exposure to Ketamine on the Developing Brain

Initially used as an analgesic and anesthetic, ketamine has unfortunately been abused as a popular recreational party drug due to its psychotropic effects. Over the last decade, ketamine has also emerged as an effective rapid-onset anti-depressant. The increasingly widespread use and misuse of the drug in infants and pregnant women has posed a concern about the neurotoxicity of ketamine to the immature brains of developing fetuses and children. In this review, we summarize recent research findings on major possible mechanisms of perinatal ketamine-induced neurotoxicity. We also briefly summarize the neuroprotective effects of ketamine in the presence of noxious stimuli. Future actions include implementation of more drug abuse education and prevention campaigns to raise the public’s awareness of the harmful effects of ketamine abuse; further investigations to justify the clinical use of ketamine as analgesic, anesthetic and anti-depressant; and further studies to develop alternatives to ketamine or treatments that can alleviate the detrimental effects of ketamine use, especially in infants and pregnant women.

Effects of low-dose ketamine infusion on remifentanil-induced acute opioid tolerance and the inflammatory response in patients undergoing orthognathic surgery

Purpose

Remifentanil is associated with acute opioid tolerance that can lead to increased postoperative consumption of opioid analgesics. The purpose of this study was to determine whether a low dose of ketamine prevents remifentanil-induced acute opioid tolerance and affects the neutrophil–lymphocyte ratio (NLR), a newly recognized biomarker of inflammation.

Materials and methods

Forty patients undergoing orthognathic surgery were enrolled in this prospective, randomized, double-blind study and randomly assigned to intraoperative administration of one of the following anesthetic regimens: high-dose remifentanil (0.6 µg/kg/minute); low-dose remifentanil (0.2 µg/kg/minute); or high-dose remifentanil with ketamine (remifentanil 0.6 µg/kg/minute with 0.5 mg/kg ketamine just after induction followed by an intraoperative infusion of ketamine 5 µg/kg/minute until wound closure). Fentanyl by intravenous patient-controlled analgesia was used for postoperative pain control. Visual Analog Scale pain scores and fentanyl consumption were recorded in the first 24 hours postoperatively. Perioperative serum C-reactive protein level and NLR were also determined.

Results

Baseline characteristics were similar in the three study groups. There were no between-group differences in Visual Analog Scale pain scores during the study period. The high-dose remifentanil group had a significantly higher requirement for fentanyl than the other two groups. Addition of ketamine did not affect the C-reactive protein level but increased the NLR; this increase was associated with decreased fentanyl consumption.

Conclusion

High-dose intraoperative remifentanil induced postoperative acute opioid tolerance that was prevented by infusion of low-dose ketamine. Ketamine increased the postoperative NLR associated with decreased fentanyl requirement for postoperative pain control.

Nonanesthetic Effects of Ketamine: A Review Article

Ketamine is considered a dissociative anesthetic medication, and it is commonly administered by a parenteral route. It works mainly by blocking the N-methyl-D-aspartate receptor. It inhibits the voltage-gated Na and K channels and serotonin and dopamine reuptake; also, it affects specific receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and aminobutyric acid A receptors. Ketamine appears to have particular mechanisms that are potentially involved during analgesic induction, including enhancing of descending inhibition and antiinflammatory effects. More recently, it has been shown that ketamine has potential in clinical practice for the management of chronic pain, cognitive function, depression, acute brain injury, and disorders of the immune system.

Intraoperative ketamine administration to prevent delirium or postoperative cognitive dysfunction: A systematic review and meta-analysis

BACKGROUND

Postoperative cognitive complications are associated with substantial morbidity and mortality. Ketamine has been suggested to have neuroprotective effects in various settings. This systematic review evaluates the effects of intraoperative ketamine administration on postoperative delirium and postoperative cognitive dysfunction (POCD).

METHODS

Medline, Embase and Central were searched to 4 March 2018 without date or language restrictions. We considered randomised controlled trials (RCTs) comparing intraoperative ketamine administration versus no intervention in adults undergoing surgery under general anaesthesia. Primary outcomes were postoperative delirium and POCD. Non-cognitive adverse events, mortality and length of stay were considered as secondary outcomes. Data were independently extracted. The quality of the evidence (GRADE approach) was assessed following recommendations from the Cochrane collaboration. Risk ratios were calculated for binary outcomes, mean differences for continuous outcomes. We planned to explore the effects of age, specific anaesthesia regimen, depth of anaesthesia and intraoperative haemodynamic events through subgroup analyses.

RESULTS

Six RCTs were included. The incidence of postoperative delirium did not differ between groups (4 trials, 557 patients, RR 0.83, 95% CI [0.25, 2.80]), but patients receiving ketamine seemed at lower risk of POCD (3 trials, 163 patients, RR 0.34, 95% CI [0.15, 0.73]). However, both analyses presented limitations. Therefore, the quality of the evidence (GRADE) was deemed low (postoperative delirium) and very low (POCD).

CONCLUSION

The effect of ketamine on postoperative delirium remains unclear but its administration may offer some protection towards POCD. Large, well-designed randomised trials are urgently needed to further clarify the efficacy of ketamine on neurocognitive outcomes.

Ketamine infusion therapy for chronic pain management in South Korea: A national survey for pain physicians with a narrative review

Although ketamine infusion therapy (KIT) has been used extensively for the treatment of chronic persistent pain, there remains high heterogeneity in the administration protocols. The aim of this study was to assess the current clinical use and the infusion protocols of KIT in South Korea and to compare the protocol details with previous relevant studies.In the first phase, an online survey about KIT, including protocol information, was distributed to pain physicians managing chronic pain patients at 47 teaching hospitals registered in the Korean Pain Society. In the second phase, a review of the KIT protocols in previous clinical studies was conducted and compared with the survey results.Among 47 institutions, 35 replied; among them, 25 institutions performed KIT on an outpatient basis. The administration protocol for KIT varied greatly among institutions: the total infusion dose of ketamine ranged from 3.5 to 140 mg/70 kg, with a mode of 70 mg [interquartile range (IQR): 62.0; 8.0-70.0 mg] administered in 1 to 3 hours. In 10 previous studies of outpatient KIT, the total dose of ketamine ranged from 12.6 to 98 mg/70 kg, with a mode of 35 mg [IQR: 40 mg; 23-63 mg] given in 1 to 4 hours, which was significantly lower than in our results (P = .01). In the survey, physicians listed hallucination as the most frequent side effect.Although KIT is used in Korean pain centers, there is wide variation regarding the specific infusion protocols. The total dose of ketamine used in South Korea is significantly higher than the general recommendations for outpatient management and may compromise patient safety. The results of this survey reinforce the need for specific guidelines for KIT in managing chronic pain that counterbalance its risks and benefits.

Breakdown of blood brain barrier as a mechanism of post-traumatic epilepsy

Traumatic brain injury (TBI) accounts for approximately 16% of acute symptomatic seizures which usually occur in the first week after trauma. Children are at higher risk for post-traumatic seizures than adults. Post-traumatic seizures are a risk factor for delayed development of epilepsy. Delayed, chronic post-traumatic epilepsy is preceded by a silent period during which therapeutic interventions may arrest, revert or prevent epileptogenesis. A number of recent review articles summarize the most important features of post-traumatic seizures and epilepsy; this review will instead focus on the link between cerebrovascular permeability, epileptogenesis and ictal events after TBI. The possibility of acting on the blood-brain barrier (BBB) and the neurovascular unit to prevent, disrupt or treat post-traumatic epilepsy is also discussed. Finally, we describe the latest quest for biomarkers of epileptogenesis which may allow for a more targeted intervention.

Effects of ketamine on the fetal transcriptomic response to umbilical cord occlusion: comparison with hypoxic hypoxia in the cerebral cortex

KEY POINTS

The cerebral response to fetal asphyxia is characterized by an upregulation of nucleic acid and chromatin modification processes, as well as a downregulation of metabolic processes at 1 h post-umbilical cord occlusion (UCO). Twenty-four hours post UCO, there was an upregulation of metabolic processes and protein modifications. UCO did not alter bacterial gene expression levels, nor did it produce a robust inflammatory response compared to maternal hypoxia. The administration of ketamine produced minimal effects on the fetal response to UCO in the cerebral cortex.

ABSTRACT

Umbilical cord occlusion (UCO) is known to cause neurological disorders in the neonate. Previously, we have reported that hypoxic hypoxia (HH) stimulates the appearance of bacteria in the fetal brain and upregulates the expression of inflammatory markers in fetal cerebral cortex (CTX) and also that ketamine attenuates these responses. In the present study, we aimed to test the hypothesis that UCO, similar to HH, produces an inflammatory response in the fetal CTX and also that treatment with ketamine reduces these effects. In chronically instrumented fetal sheep (∼125 days), 30 min of partial UCO decreased fetal P a O 2 levels by ∼50%. Half of the fetuses received ketamine (3 mg kg^-1 ) 10 min prior to UCO (n = 4 per group). Fetal brains were collected 1 and 24 h after the experiment and mRNA was extracted and hybridized for microarray analyses. Differentially-expressed genes were analysed for significant association with gene ontologies and pathways. After 1 h, UCO upregulated nucleic acid processing and chromatin modification and downregulated metabolic processes compared to control. After 24 h, UCO upregulated metabolic and protein modification processes. Ketamine produced minimal effects. UCO did not alter the abundance of bacterial DNA in fetal brain, nor did it upregulate inflammation pathways compared to HH. We conclude that UCO produced time-dependent responses that did not include bacterial invasion or upregulation of inflammation pathways in fetal CTX. This contrasts with the response to HH, which resulted in the appearance of bacteria in the CTX and upregulated inflammation pathways. These responses in fetal CTX to oxygen deprivation are therefore modified by the maternal or placental response to the stimulus.

Ketamine and Ketamine Metabolite Pharmacology: Insights into Therapeutic Mechanisms

Ketamine, a racemic mixture consisting of (S)- and (R)-ketamine, has been in clinical use since 1970. Although best characterized for its dissociative anesthetic properties, ketamine also exerts analgesic, anti-inflammatory, and antidepressant actions. We provide a comprehensive review of these therapeutic uses, emphasizing drug dose, route of administration, and the time course of these effects. Dissociative, psychotomimetic, cognitive, and peripheral side effects associated with short-term or prolonged exposure, as well as recreational ketamine use, are also discussed. We further describe ketamine's pharmacokinetics, including its rapid and extensive metabolism to norketamine, dehydronorketamine, hydroxyketamine, and hydroxynorketamine (HNK) metabolites. Whereas the anesthetic and analgesic properties of ketamine are generally attributed to direct ketamine-induced inhibition of N-methyl-D-aspartate receptors, other putative lower-affinity pharmacological targets of ketamine include, but are not limited to, γ-amynobutyric acid (GABA), dopamine, serotonin, sigma, opioid, and cholinergic receptors, as well as voltage-gated sodium and hyperpolarization-activated cyclic nucleotide-gated channels. We examine the evidence supporting the relevance of these targets of ketamine and its metabolites to the clinical effects of the drug. Ketamine metabolites may have broader clinical relevance than was previously considered, given that HNK metabolites have antidepressant efficacy in preclinical studies. Overall, pharmacological target deconvolution of ketamine and its metabolites will provide insight critical to the development of new pharmacotherapies that possess the desirable clinical effects of ketamine, but limit undesirable side effects.