Pharmacological aspects and potential new clinical applications of ketamine: reevaluation of an old drug

High-Frequency Analysis of the Cerebral Physiological Impact of Ketamine in Acute Traumatic Neural Injury

Acute traumatic neural injury, also known as traumatic brain injury (TBI), is a leading cause of death. TBI treatment focuses on the use of sedatives, vasopressors, and invasive intracranial pressure (ICP) monitoring to mitigate ICP elevations and maintain cerebral perfusion pressure (CPP). While common sedatives such as propofol and fentanyl have significant side effects, ketamine is an attractive alternative due to its rapid onset and cardiovascular stability. Despite these benefits, ketamine's use remains controversial due to historical concerns about increasing ICP. Using high-frequency monitoring, this retrospective study compared cerebral pressure-flow dynamics in patients with moderate/severe TBI who received ketamine with those who did not. Statistical analysis included descriptive statistics, comparisons within and between patients receiving ketamine, and evaluation of physiological response around incremental dose changes in ketamine. Various cerebral physiological indices were analyzed, including ICP, CPP, regional cerebral oxygen delivery, intracranial compliance, and cardiovascular reactivity metrics. A total of 122 patients were studied, with 17 receiving ketamine (median age: 37 years) and 105 not receiving ketamine (median age: 42 years). Results indicated higher median ICP in the ketamine group compared with the no ketamine group (9.05 mmHg and 14.00 mmHg, respectively, p = 0.00017); however, this is likely due to differences in patient characteristics and injury severity between the groups. No significant differences were observed in any other index of cerebral pressure-flow dynamics or between any incremental dose change condition. These findings suggest that ketamine does not significantly impact cerebral pressure-flow dynamics, challenging historical concerns about its use in patients with TBI.

Current and Evolving Concepts in the Management of Complex Regional Pain Syndrome: A Narrative Review

Background/Objectives: Complex regional pain syndrome (CRPS) is characterized by severe pain and reduced functionality, which can significantly affect an individual's quality of life. The current treatment of CRPS is challenging. However, recent advances in diagnostic and treatment methods show promise for improving patient outcomes. This review aims to place the question of CRPS in a broader context and highlight the objectives of the research for future directions in the management of CRPS. Methods: This study involved a comprehensive literature review. Results: Research has identified three primary pathophysiological pathways that may explain the clinical variability observed in CRPS: inflammatory mechanisms, vasomotor dysfunction, and maladaptive neuroplasticity. Investigations into these pathways have spurred the development of novel diagnostic and treatment strategies focused on N-Methyl-D-aspartate Receptor Antagonists (NMDA), Toll-like receptor 4 (TLR-4), α1 and α2 adrenoreceptors, as well as the identification of microRNA (miRNA) biomarkers. Treatment methods being explored include immune and glial-modulating agents, intravenous immunoglobulin (IVIG) therapy, plasma exchange therapy, and neuromodulation techniques. Additionally, there is ongoing debate regarding the efficacy of other treatments, such as free radical scavengers, alpha-lipoic acid (ALA), dimethyl fumarate (DMF), adenosine monophosphate-activated protein kinase (AMPK) activators such as metformin, and phosphodiesterase-5 inhibitors such as tadalafil. Conclusions: The controversies surrounding the mechanisms, diagnosis, and treatment of CRPS have prompted researchers to investigate new approaches aimed at enhancing understanding and management of the condition, with the goal of alleviating symptoms and reducing associated disabilities.

Mitochondrial damage causes inflammation via cGAS-STING signaling in ketamine-induced cystitis

BACKGROUND

Mitochondrial dysfunction and damage can result in the release of mitochondrial DNA (mtDNA) into the cytoplasm, which subsequently activates the cGAS-STING pathway, promoting the onset of inflammatory diseases. Various factors, such as oxidative stress, viral infection, and drug toxicity, have been identified as inducers of mitochondrial damage. This study aims to investigate the role of mtDNA as a critical inflammatory mediator in the pathogenesis of ketamine (KET)-induced cystitis (KC) through the cGAS-STING pathway.

METHODS

To investigate the role of the cGAS-STING pathway in KET-induced cystitis, we assessed the expression of cGAS and STING in rats with KET cystitis. Additionally, we evaluated STING expression in conditionally deficient Simian Virus-transformed Human Uroepithelial Cell Line 1 (SV-HUC-1) cells in vitro. Morphological changes in mitochondria were examined using transmission electron microscopy. We measured intracellular reactive oxygen species (ROS) production through flow cytometry and immunofluorescence techniques. Furthermore, alterations in associated inflammatory factors and cytokines were quantified using real-time quantitative PCR with fluorescence detection.

RESULTS

We observed up-regulation of cGAS and STING expressions in the bladder tissue of rats in the KET group, stimulation with KET also led to increased cGAS and STING levels in SV-HUC-1 cells. Notably, the knockdown of STING inhibited the nuclear translocation of NF-κB p65 and IRF3, resulting in a decrease in the expression of inflammatory cytokines, including IL-6, IL-8, and CXCL10. Additionally, KET induced damage to the mitochondria of SV-HUC-1 cells, facilitating the release of mtDNA into the cytoplasm. This significant depletion of mtDNA inhibited the activation of cGAS-STING pathway, subsequently affecting the expression of NF-κB p65 and IRF3. Importantly, the reintroduction of mtDNA after STING knockdown partially restored the inflammatory response.

CONCLUSION

Our findings confirmed the activation of the cGAS-STING pathway in KC rats and revealed mitochondrial damage in vitro. These results highlight the involvement of the cGAS-STING pathway in the pathogenesis of KC, suggesting its potential as a therapeutic target for intervention.

Impact of different doses of esketamine on the incidence of hypotension in propofol-based sedation for colonoscopy: a randomized controlled trial

Background

Hypovolemia is common in colonoscopy due to fasting and bowel preparation, and propofol itself can reduce systemic vascular resistance, resulting in relative hypovolemia. Therefore, hypotension is not a rare event during propofol-based sedation for colonoscopy.

Objectives

Our objective was to explore the efficacy of esketamine as a sedative adjuvant in reducing the incidence of hypotension during colonoscopy.

Design

This was a prospective randomized trial. The trial was registered with the Chinese Clinical Trial Registry (ID: ChiCTR 2100047032).

Methods

We included 100 eligible patients who planned to receive a colonoscopy and randomly divided them into 4 groups with 25 patients in each group, which were propofol 2 mg/kg (Group P), propofol 1 mg/kg with esketamine 0.2 mg/kg (Group E1), propofol 1 mg/kg with esketamine 0.3 mg/kg (Group E2), and propofol 1 mg/kg with esketamine 0.4 mg/kg (Group E3). The hemodynamic and respiratory parameters were documented at various times during the procedure, including the patient's entry into the endoscopic room (T0), the induction of sedation (T1), the insertion of the colonoscope (T2), the removal of the colonoscope (T3), and the awakening of the patient (T4). The primary outcome was the incidence of hypotension. Secondary outcomes were cardiovascular side effects other than hypotension, incidence of hypoxia, cumulative changes in cardiovascular and respiratory parameters, total propofol dosage, anesthesia recovery time, and satisfactory levels of both patients and endoscopists.

Results

The incidence of hypotension in Group E1 (16%), Group E2 (16%), and Group E3 (12%) was significantly lower than in Group P (60%), with p values 0.003, 0.003, and <0.001 respectively. The cumulative changes in diastolic blood pressure and mean arterial pressure in Groups E1, E2, and E3 were significantly higher than in Group P (p = 0.024, p < 0.001, p = 0.006, respectively). Cumulative changes in systolic blood pressure in Group E3 were significantly higher than those in Group P (p = 0.012). The respiratory-related parameters were not statistically significant.

Conclusions

This study showed that the application of 0.4 mg/kg esketamine in propofol-based sedation reduced the incidence of hypotension during colonoscopy while providing satisfactory sedation.

Subhypnotic Intravenous Ketamine Improves Patient Satisfaction With Burn Wound Care: A Quality Improvement Project

Despite advancements in pain management for burn injuries, analgesia often fails to meet our patients' needs. We hypothesized that low doses of intravenous (IV) ketamine as an adjunct to our current protocol would be safe, improving both nurse and patient satisfaction with analgesia during hydrotherapy. Burn patients admitted who underwent hydrotherapy from June 1, 2021, to June 30, 2023 were surveyed. Ketamine was administered with the standard opioid-midazolam regimen. Demographics, oral morphine equivalents, midazolam, ketamine doses and time of administration, and adverse events were collected. Patient and nurse satisfaction scores were collected. The ketamine and no-ketamine groups were compared. P < .05 was considered significant. Eighty-five hydrotherapies were surveyed, 47 without ketamine, and 38 with ketamine. Demographics, comorbidities, %TBSA, and hospital length of stay were not different. The median amount of ketamine given was 0.79 mg/kg [0.59-1.06]. Patients who received ketamine were more likely to receive midazolam (100% vs 61.7%; P < .001), and both oral and IV opioids (94.7% vs 68.1%; P = .002) prior to hydrotherapy and less likely to receive rescue opioids or midazolam during hydrotherapy. Two patients in the ketamine group had hypertension (defined as SBP > 180) that did not require treatment. Nurses tended to be more satisfied with patient pain control when ketamine was used (10 [8-10] vs 9 [7-10], P = .072). Patient satisfaction was higher in the ketamine group (10 [8.8-10] vs 9 [7-10], P = .006). Utilizing subhypnotic dose of IV ketamine for hydrotherapy is safe and associated with increased patient satisfaction.

The Use of Ketamine for Malignant and Nonmalignant Chronic Pain in Children: A Review of Current Evidence

Chronic pain in children continues to pose significant challenges. The pharmacological approach most often revolves around trials and errors, expert opinions, and extrapolation of adult study findings. Ketamine is one of the agents used for chronic pain, especially with a neuropathic component. This article aims to provide an overview of its properties and highlight the current evidence for its use in malignant and nonmalignant chronic pain management. A search on the use of ketamine for chronic pain in children up to 18 years of age covering the period from January 1, 2000, to December 14, 2022, was performed through PubMed, Cochrane Library, EBSCO, EBM Review, Wiley, BMJ, Web of Science, Google Scholar, and the Saudi Digital Library. 218 articles were found and 42 underwent full review. Currently, the evidence about ketamine efficacity and safety for chronic pain management is at best of moderate to low quality. The heterogeinity of ketamine infusion protocols and frequent concomitant use of other analgesics make it difficult to draw robust conclusions. The long-term effect of prolonged usage also remains a concern. Nevertheless, with careful monitoring, the drug may be a reasonable choice for malignant and nonmalignant pain management in selected cases, especially for refractory pain not responding to conventional approaches.

Effects of carvacrol on ketamine-induced cardiac injury in rats: an experimental study

AIM

We aimed to investigate the preventive effects of carvacrol against ketamine-induced cardiotoxicity biochemically and histopathologically in an experimental model.

MATERIAL AND METHOD

The rats were divided into three groups; healthy control (HC), ketamine alone (KG), and ketamine + carvacrol (KCG) groups. Serum Creatine Kinase Myocardial Band (CK-MB) and Troponin I (TP I) levels were determined. Malondialdehyde (MDA), Glutathione (GSH), Superoxide Dismutase (SOD), Tumor Necrosis Factor α (TNF-α), Interleukin 1 beta (IL-1beta), and Interleukin 6 (IL-6) levels were measured in the heart tissues of the rats. Heart tissues were also evaluated histopathologically.

RESULTS

In the ketamine-treated group, tissue MDA, TNF-α, IL-1beta, and IL-6 levels increased while tissue GSH and SOD levels decreased significantly compared with the control group. However, in the ketamine plus carvacrol applied group, all those alterations were significantly less pronounced, close to the healthy controls. Severe mononuclear cell infiltrations, degenerated myocytes and hemorrhage were determined in the ketamine alone administered group, and these alterations were at a mild level in the carvacrol + ketamine administered group.

CONCLUSION

Prolonged exposure to ketamine resulted in induced oxidative stress in rat heart tissue; concomitant carvacrol application could counteract the negative effects of ketamine by protecting tissues from lipid peroxidation and decreasing the inflammatory response.

Effect of esketamine-based opioid-sparing anesthesia strategy on postoperative pain and recovery quality in patients undergoing total laparoscopic hysterectomy: A randomized controlled trail

Objective

Opioid-sparing anesthesia reduces intraoperative use of opioids and postoperative adverse reactions. The current study investigated the effect of esketamine-based opioid-sparing anesthesia on total laparoscopic hysterectomy patients' recovery.

Methods

Ninety patients undergoing total laparoscopic hysterectomy were randomly assigned to esketamine-based group (group K) or opioid-based group (group C). The allocation to groups was unknown to patients, surgeons, and postoperative medical staff. The inability to implement blinding for anesthesiologists was due to the distinct procedures followed by the various groups while administering drugs. The QoR-40 and VAS were used to measure recovery quality. Postoperative adverse events, perioperative opioid consumption, and intraoperative hemodynamics were secondary endpoints.

Results

There was an absence of notable discrepancy in the baseline data observed between the two groups. The QoR-40 scores exhibited greater values in group K when compared to group C on the first day following the surgical procedure (160.91 ± 9.11 vs 151.47 ± 8.35, respectively; mean difference 9.44 [95 %CI: 5.78-13.11]; P < 0.01). Within 24 h of surgery, the VAS score of group K was lower at rest and during movement. (P < 0.05 for each). Group K had much lower rates of nausea and vomiting within 24 h of surgery. (P < 0.05 for each). Group K received significantly lower total doses of sufentanil and remifentanil than group C. (17.28 ± 2.59 vs 43.43 ± 3.52; 0.51 ± 0.15 vs 1.24 ± 0.24). The proportion of patients who used ephedrine in surgery was higher in group C than in group K (P < 0.05).

Conclusions

Esketamine-based opioid-sparing anesthesia strategy is feasible and enhanced recuperation following surgery by decreasing adverse effects associated with opioids and pain scores compared to an opioid-based anesthetic regimen.

Novel Targets and Drug Delivery System in the Treatment of Postoperative Pain: Recent Studies and Clinical Advancement

Pain is generated by a small number of peripheral targets. These can be made more sensitive by inflammatory mediators. The number of opioids prescribed to the patients can be reduced dramatically with better pain management. Any therapy that safely and reliably provides extended analgesia and is flexible enough to facilitate a diverse array of release profiles would be useful for improving patient comfort, quality of care, and compliance after surgical procedures. Comparisons are made between new and traditional methods, and the current state of development has been discussed; taking into account the availability of molecular and cellular level data, preclinical and clinical data, and early post-market data. There are a number of benefits associated with the use of nanotechnology in the delivery of analgesics to specific areas of the body. Nanoparticles are able to transport drugs to inaccessible bodily areas because of their small molecular size. This review focuses on targets that act specifically or primarily on sensory neurons, as well as inflammatory mediators that have been shown to have an analgesic effect as a side effect of their anti- inflammatory properties. New, regulated post-operative pain management devices that use existing polymeric systems were presented in this article, along with the areas for potential development. Analgesic treatments, both pharmacological and non-pharmacological, have also been discussed.

NRX-101, a Rapid-Acting Anti-Depressant, Does Not Cause Neurotoxicity Following Ketamine Administration in Preclinical Models

Agents that act at the N-methyl-D-aspartate receptor (NMDAR), such as ketamine, have gained increasing attention as rapid-acting antidepressants; however, their use has been limited by potential neurotoxicity. Recent FDA guidance requires a demonstration of safety on histologic parameters prior to the initiation of human studies. D-cycloserine (DCS) is a partial NMDA agonist that, along with lurasidone, is being investigated as a treatment for depression. The current study was designed to investigate the neurologic safety profile of DCS. To this end, female Sprague Dawley rats (n = 106) were randomly divided into 8 study groups. Ketamine was administered via tail vein infusion. DCS and lurasidone were administered via oral gavage in escalating doses to a maximum of 2000 mg/kg DCS. To ascertain toxicity, dose escalation with 3 different doses of D-cycloserine/lurasidone was given in combination with ketamine. MK-801, a known neurotoxic NMDA antagonist, was administered as a positive control. Brain tissue was sectioned and stained with H&E, silver, and Fluoro-Jade B stains. No fatalities were observed in any group. No microscopic abnormalities were found in the brain of animal subjects given ketamine, ketamine followed by DCS/lurasidone, or DCS/lurasidone alone. Neuronal necrosis, as expected, was seen in the MK-801 (positive control) group. We conclude that NRX-101, a fixed-dose combination of DCS/lurasidone, when administered with or without prior infusion of IV ketamine was tolerated and did not induce neurotoxicity, even at supratherapeutic doses of DCS.

Evidence-Based Guidelines for Prehospital Pain Management: Recommendations

This project sought to develop evidence-based guidelines for the administration of analgesics for moderate to severe pain by Emergency Medical Services (EMS) clinicians based on a separate, previously published, systematic review of the comparative effectiveness of analgesics in the prehospital setting prepared by the University of Connecticut Evidence-Based Practice Center for the Agency for Healthcare Research and Quality (AHRQ). A technical expert panel (TEP) was assembled consisting of subject matter experts in prehospital and emergency care, and the development of evidence-based guidelines and patient care guidelines. A series of nine "patient/population-intervention-comparison-outcome" (PICO) questions were developed based on the Key Questions identified in the AHRQ systematic review, and an additional PICO question was developed to specifically address analgesia in pediatric patients. The panel made a strong recommendation for the use of intranasal fentanyl over intravenous (IV) opioids for pediatric patients without intravenous access given the supporting evidence, its effectiveness, ease of administration, and acceptance by patients and providers. The panel made a conditional recommendation for the use of IV non-steroidal anti-inflammatory drugs (NSAIDs) over IV acetaminophen (APAP). The panel made conditional recommendations for the use of either IV ketamine or IV opioids; for either IV NSAIDs or IV opioids; for either IV fentanyl or IV morphine; and for either IV ketamine or IV NSAIDs. A conditional recommendation was made for IV APAP over IV opioids. The panel made a conditional recommendation against the use of weight-based IV ketamine in combination with weight-based IV opioids versus weight-based IV opioids alone. The panel considered the use of oral analgesics and a conditional recommendation was made for either oral APAP or oral NSAIDs when the oral route of administration was preferred. Given the lack of a supporting evidence base, the panel was unable to make recommendations for the use of nitrous oxide versus IV opioids, or for IV ketamine in combination with IV opioids versus IV ketamine alone. Taken together, the recommendations emphasize that EMS medical directors and EMS clinicians have a variety of effective options for the management of moderate to severe pain in addition to opioids when designing patient care guidelines and caring for patients suffering from acute pain.

The effects of intravenous tramadol vs. intravenous ketamine in the prevention of shivering during spinal anesthesia: A meta-analysis of randomized controlled trials

Background

Shivering is a common complication after subarachnoid administration of local anesthetics. Intravenous ketamine and tramadol are widely available anti-shivering drugs, especially in developing settings. This meta-analysis aimed to compare the effects of intravenous ketamine vs. tramadol for post-spinal anesthesia shivering.

Materials and methods

PubMed/MEDLINE, Web of Science, Cochrane Library, Embase, and Google Scholar databases were used to search for relevant articles for this study. Mean difference (MD) with 95% confidence interval (CI) was used to analyze continuous outcomes, and risk ratio (RR) with 95% CI to analyze categorical results. The heterogeneity of the included studies was assessed using the I2 test. We utilized Review Manager 5.4.1 to perform statistical analysis.

Results

Thirteen studies involving 1,532 patients were included in this meta-analysis. Ketamine had comparable effects in preventing post-spinal anesthetics shivering [RR = 1.06; 95% CI (0.94, 1.20), P = 0.33, I ² = 77], and onset of shivering [MD = -0.10; 95%CI (- 2.68, 2.48), P = 0.94, I ² = 0%], lower incidences of nausea and vomiting [RR = 0.51; 95%CI (0.26, 0.99), P = 0.05, I ² = 67%], and lower incidences of bradycardia [RR = 0.16; 95%CI (0.05, 0.47), P = 0.001, I ² = 33%], higher incidence of hallucinations [RR = 12; 95%CI (1.58, 91.40), P = 0.02, I ² = 0%], and comparable effects regarding the incidences of hypotension [RR = 0.60; 95%CI (0.30, 1.21), P = 0.15, I ² = 54%] as compared to tramadol.

Conclusions

Intravenous ketamine and tramadol are comparable in the prevention of post-spinal anesthetic shivering. Ketamine had a better outcome with less occurrences of nausea, vomiting, and bradycardia. However, ketamine was associated with higher incidences of hallucinations than tramadol.

Advantages of ketamine in pediatric anesthesia

Although ketamine is primarily used for induction and maintenance of general anesthesia, it also presents sedative, amnestic, anesthetics, analgesic, antihyperalgesia, neuroprotective, anti-inflammatory, immunomodulant, and antidepressant effects. Its unique pharmacodynamics and pharmacokinetic properties allow the use of ketamine in various clinical settings including sedation, ambulatory anesthesia, and intensive care practices. It has also adopted to manage acute and chronic pain management. Clinically, ketamine produces dissociative sedation, analgesia, and amnesia while maintaining laryngeal reflexes, with respiratory and cardiovascular stability. Notably, it does not cause respiratory depression, maintaining both the hypercapnic reflex and the residual functional capacity with a moderate bronchodilation effect. In the pediatric population, ketamine can be administered through practically all routes, making it an advantageous drug for the sedation required setting such as placement of difficult vascular access and in uncooperative and oppositional children. Consequently, ketamine is indicated in prehospital induction of anesthesia, induction of anesthesia in potentially hemodynamic unstable patients, and in patients at risk of bronchospasm. Even more, ketamine does not increase intracranial pressure, and it can be safely used also in patients with traumatic brain injuries. This article is aimed to provide a brief and practical summary of the role of ketamine in the pediatric field.

Re-evaluating methods reporting practices to improve reproducibility: an analysis of methodological rigor for the Langendorff whole-heart technique

In recent decades, the scientific community has seen an increased interest in rigor and reproducibility. In 2017, concerns of methodological thoroughness and reporting practices were implicated as significant barriers to reproducibility within the preclinical cardiovascular literature, particularly in studies employing animal research. The Langendorff, whole-heart technique has proven to be an invaluable research tool, being modified in a myriad of ways to probe questions across the spectrum of physio- and pathophysiologic function of the heart. As a result, significant variability in the application of the Langendorff technique exists. This literature review quantifies the different methods employed in the implementation of the Langendorff technique and provides brief examples of how individual parametric differences can impact the outcomes and interpretation of studies. From 2017-2020, significant variability of animal models, anesthesia, cannulation time, and perfusate composition, pH, and temperature demonstrate that the technique has diversified to meet new challenges and answer different scientific questions. The review also reveals which individual methods are most frequently reported, even if there is no explicit agreement upon which parameters should be reported. The analysis of methods related to the Langendorff technique suggests a framework for considering methodological approach when interpreting seemingly contradictory results, rather than concluding that results are irreproducible.

Different modalities of analgesia in open heart surgeries in Mansoura University

Background: Opioid usage in cardiac surgery is considered to be the corner stone in management. Inadequate pain control after cardiac surgery complicates patient recovery and increases the load on healthcare services. Multimodal analgesia can be used to achieve better analgesic effect and improves patient outcome.  Material and methods: A total of 90 patients undergoing cardiac surgery with median sternotomy were randomly allocated equally into three groups intraoperatively where first group received continuous infusion of high dose opioids, second group received boluses of low dose opioids and third group received multimodal non opioid analgesics including dexmedetomidine, ketamine and magnesium sulphate. All patients received the same post-operative analgesic regimen consists of morphine patient controlled analgesia (PCA). Results: Patients in multimodal non opioid group had more stable hemodynamics intra and postoperatively. Also, patients in multimodal group had lower pain scores extubation, earlier extubation, shorter ICU stay, earlier mobilization and earlier return of bowel movements compared to patients of both groups received intraoperative higher opioid doses.

Effect of low-dose intravenous ketamine on postoperative pain following cesarean section under spinal anesthesia: A prospective cohort study, Ethiopia

Background

Following cesarean delivery, mothers experience moderate to severe pain since postoperative analgesia of spinal anesthesia is limited by duration of local anesthetic agents used. Analgesic effect of local anesthetic agents could be extended and supported by adding either intravenous or intrathecal adjuvants. The primary outcome of this study is to assess effect of low-dose intravenous ketamine on postoperative pain following cesarean section under spinal anesthesia.

Materials and methods

This prospective observational cohort study recruits 60 parturients who underwent elective cesarean delivery under spinal anesthesia. Those parturients who received intravenous ketamine 0.25 mg/kg following spinal anesthesia were considered as exposed group/ketamine group. The Non-exposed group was those parturients who didn't receive intravenous ketamine following spinal anesthesia. Numerical rating scale pain score, time to request first analgesia and total analgesia consumptions were recorded starting from 1st hour to 24 h after the end of surgery.

Results

The median and Inter quartile range (IQR) for postoperative numerical rating scale pain score was significantly higher in non-exposed group compered to ketamine group at 1st and 2nd hour after operation (P-value<0.05). Time to request first analgesia was significantly longer in ketamine group [192.5(140–210) minutes] compared to non-Exposed group [146(130–160) minutes] with P-value < 0.001. Tramadol consumption within 24 h postoperatively were significantly lower in ketamine group compared to non-exposed group (P-value < 0.001).

Conclusion

Low dose intravenous ketamine before skin incision was extended postoperative first analgesia request time by average of 45.5 min and decrease total analgesia consumption in 24 h.

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Ketamine group recorded significantly lower median pain NRS score at 1st and 2nd hour after operation.

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Total analgesic consumption within 24 h was less in ketamine group.

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First analgesia requestion time were longer in ketamine compared to non-exposed group postoperatively.

Ketamine in Acute Brain Injury: Current Opinion Following Cerebral Circulation and Electrical Activity

The use of ketamine in patients with TBI has often been argued due to its possible deleterious effects on cerebral circulation and perfusion. Early studies suggested that ketamine could increase intracranial pressure, decreasing cerebral perfusion pressure and thereby reducing oxygen supply to the damaged cerebral cortex. Some recent studies have refuted these conclusions relating to the role of ketamine, especially in patients with TBI, showing that ketamine should be the first-choice drug in this type of patient at induction. Our narrative review collects evidence on ketamine’s use in patients with TBI. Databases were examined for studies in which ketamine had been used in acute traumatic brain injury (TBI). The outcomes considered in this narrative review were: mortality of patients with TBI; impact on intracranial pressure and cerebral perfusion pressure; blood pressure and heart rate values; depolarization rate; and preserved neurological functions. 11 recent studies passed inclusion and exclusion criteria and were included in this review. Despite all the benefits reported in the literature, the use of ketamine in patients with brain injury still appears to be limited. A slight increase in intracranial pressure was found in only two studies, while two smaller studies showed a reduction in intracranial pressure after ketamine administration. There was no evidence of harm from the ketamine’s use in patients with TBI.

Ketamine versus magnesium sulphate as an adjuvant to local anesthetics in the peribulbar block for posterior segment surgeries: a randomized controlled study

BACKGROUND

The use of an adjuvant to local anesthetics in the peribulbar block may improve block characteristics. The aim of this double-blinded, parallel-group, randomized, controlled trial was to evaluate the safety and efficacy of ketamine versus magnesium sulphate as adjuvants to the local anesthetic mixture of peribulbar block in patients scheduled for vitreoretinal surgeries.

METHODS

A total of 126 patients scheduled for vitreoretinal surgery were randomly allocated as either ketamine (GK, n=42), magnesium sulphate (GM, n=42), or control (GC, n=42) groups. The primary outcomes were the onset and duration of globe akinesia, duration of lid akinesia, and onset of sensory block. Secondary outcomes included time to start surgery, duration of analgesia, intraocular pressure, and patient and surgeon satisfaction.

RESULTS

The use of either ketamine or magnesium significantly shortened the onset of globe akinesia, enhanced the onset of sensory block, prolonged the duration of globe and lid akinesia, minimized the time required to start surgery, and increased the total analgesic time. The effect of magnesium was significantly more pronounced on durations of globe and lid akinesia as well as analgesia, whereas ketamine significantly shortened the time required to start surgery. Both patient and surgeon satisfaction were significantly improved with the use of either drug.

CONCLUSIONS

In vitreoretinal surgeries the use of either ketamine or magnesium sulphate as adjuvants to the local anesthetic mixture of peribulbar block improved the onset, duration, and quality of the block, offered better patient and surgeon satisfaction, and was not associated with drug adverse effects or surgical complications.

Ketamine treatment upon memory retrieval reduces fear memory in marmoset monkeys

Emotionally arousing experiences are retained very well as seen in posttraumatic stress disorder (PTSD). Various lines of evidence indicate that reactivation of these memories renders them labile which offers a potential time-window for intervention. We tested in non-human primates whether ketamine, administered during fear memory reactivation, affected passive (inhibitory) avoidance learning. For the consolidation of contextual emotional memory, the unescapable foot-shock paradigm in a passive avoidance task with two compartments (dark vs illuminated) was used. After entering the dark compartment, marmoset monkeys received four random foot-shocks (1 mA, 4 s) within 15-min. This stressful exposure increased the saliva cortisol and heart rate and impaired REM-sleep (p<0.05). One week later the monkeys were re-exposed to the stressful situation for the reconsolidation of the fearful experience. During the re-exposure the monkeys were treated with ketamine (0.5 mg/kg) or saline. In week 3, the monkeys were placed in the experimental setting to test their memory for the fearful experience. In contrast to the vehicle-treated monkeys, who avoided the dark compartment, the ketamine-treated monkeys entered the dark compartment that was previously associated with the fearful experience (p<0.05). Post-mortem analysis of the hippocampus showed that ketamine-treated animals exhibited less doublecortin positive neurons and BrdU-labeled cells in the dentate gyrus. This study reveals that a single low dose of ketamine, administered upon fear retrieval in monkeys, reduce contextual fear memory and attenuate neurogenesis in the hippocampus. These are important findings for considering ketamine as a potential candidate to target traumatic memories in PTSD.

Ketamine as an Anesthetic for Patients with Acute Brain Injury: A Systematic Review

For years, the use of ketamine as an anesthetic to patients suffering from acute brain injury has been debated because of its possible deleterious effects on the cerebral circulation and thus on the cerebral perfusion. Early studies suggested that ketamine could increase the intracranial pressure thus lowering the cerebral perfusion and hence reduce the oxygen supply to the injured brain. However, more recent studies are less conclusive and might even indicate that patients with acute brain injury could benefit from ketamine sedation. This systematic review summarizes the evidence regarding the use of ketamine in patients suffering from traumatic brain injury. Databases were searched for studies using ketamine in acute brain injury. Outcomes of interest were mortality, intracranial pressure, cerebral perfusion pressure, blood pressure, heart rate, spreading depolarizations, and neurological function. In total 11 studies were included. The overall level of evidence concerning the use of ketamine in brain injury is low. Only two studies found a small increase in intracranial pressure, while two small studies found decreased levels of intracranial pressure following ketamine administration. We found no evidence of harm during ketamine use in patients suffering from acute brain injury.

Kratom Ingestion and Emergency Care: Summary and a Case Report

Kratom ingestion for its psychotropic effect or to self-treat opioid withdrawal symptoms has increased over the last 10 years in the United States. Although mild adverse effects have been observed in users, reports of respiratory failure and shock after kratom consumption remain rare. In this case, a 35-year-old man initially presented to the emergency department with profound circulatory shock, metabolic acidosis, hypoxia, and symptoms of autonomic nervous system dysfunction. The patient required vasopressor support, multiregimen sedation and rapid sequence intubation, mechanical ventilation, and emergent hemodialysis. Within 72 hours, the patient's condition stabilized, and he was extubated. The patient reported regular consumption of large quantities of kratom as well as injection of heroin and cocaine. In this report, a rare clinical presentation after kratom ingestion is described.

Refractory symptoms in paediatric palliative care: can ketamine help?

BACKGROUND

One of the main challenges for paediatric palliative care (PPC) is the management of concomitant, different and severe symptoms that frequently affect the quality of life of PPC patients and are often refractory to commonly used pharmacological treatments. Consequently, many efforts are still needed to find the best therapeutic options to handle these refractory conditions. Since the first synthesis of ketamine in the 1960s, its pharmacokinetic and pharmacodynamic properties have been largely investigated and its potential wide range of clinical applications has become clear. However, this molecule still receives poor attention in some areas, including in children and PPC. This narrative review analyses the use of ketamine in children and the potential extension of its applications in PPC in order to provide new options for treatment in the PPC setting.

METHODS

Scientific papers published before October 2020 on MEDLINE, EMBASE and the Cochrane Library were considered. The cited references of the selected papers and the authors' personal collections of literature were reviewed. The terms "palliative care", "ketamine", "neuropathic pain", "procedural pain", "status epilepticus", "refractory pain" and "child", adding "age: birth-18 years" on a further filter were used for the search.

DISCUSSION

The use of ketamine in PPC should be more widely considered due to its overall favourable safety profile and its efficacy, which are supported by an increasing number of studies, although in settings different from PPC and of mixed quality. Ketamine should be proposed according to a case-by-case evaluation and the specific diagnosis and the dosage and route of administration should be tailored to the specific needs of patients. Furthermore, there is evidence to suggest that ketamine is safe and efficacious in acute pain. These findings can prompt further research on the use of ketamine for the treatment of acute pain in PPC.

CONCLUSION

Ketamine could be a suitable option after the failure of conventional drugs in the treatment of different refractory conditions in PPC.

The effect of ketamine on preventing postpartum depression

Postpartum depression is a common disabling psychosocial disorder that could have adverse effects on the life of the mother, infant, and family. The present study was conducted to evaluate the effect of ketamine on preventing postpartum depression in women undergoing caesarian sections considering the relatively known positive effect of ketamine on major depression. The present double-blind, randomized clinical trial was conducted on 134 women undergoing scheduled caesarian sections. Participants were randomly allocated into two groups of control and intervention. To induce anesthesia, 1–2 mg/kg of body weight of Nesdonal and 0.5 mg/kg of body weight of ketamine were used in the intervention group, while only 3–5 mg/kg of body weight Nesdonal was administered in the control group. Data were gathered using the Edinburgh Postnatal Depression Scale (EPDS) in three stages: before the caesarian section and two and four weeks after the caesarian section. Data were analyzed using variance analysis with repeated measures and the Chi-square test. Results of the present study showed that the mean (± standard deviation) of the depression score in the intervention and control groups were 13.78±3.87 and 13.79±4.78(p = 0.98) before the caesarian section, 11.82±3.41 and 14.34±4.29 (p < 0.001) two weeks after and 10.84±3.48 and 13.09±3.79 (p = 0.001) four weeks after the caesarian section, respectively. Using ketamine in the induction of general anesthesia could be effective in preventing postpartum depression. However, further studies are required to strengthen these findings.

The role of short-term, low dose intravenous ketamine infusion in Calciphylaxis

Calciphylaxis is a small vessel vasculopathy causing subcutaneous ischemic necrosis. This condition is a recognized complication of end stage renal disease and is associated with severe pain. The mechanism of the pain generated by calciphylaxis is thought to be partly related to tissue ischemia, with a significant neuropathic component associated with neuronal hypoxic injury. The pain can be further exacerbated by the inflammatory process ensuing as a result of calciphylactic lesion infections which are commonly associated with this condition. Obtaining adequate pain relief is a challenging aspect of symptom control in calciphylaxis, and historically, patients suffering from calciphylaxis required high dose opioid medications to achieve satisfactory analgesia.This case report presents a multimodal pain management approach utilizing low dose ketamine infusion in an opioid-tolerant patient suffering from severe calciphylaxis-related pain. Ketamine is an anesthetic agent well established for its efficacy in the management of neuropathic pain in opioid-tolerant patients, and has been shown to prevent opioid-induced hyperalgesia and decrease opioid requirements. Prior published data studying pain control in calciphylaxis have mainly focused on subcutaneous ketamine administration which as noted in the literature, can be associated with infusion site complications. To the best of our knowledge, this report is first of its kind to describe successful use of ketamine infusion in treatment of acute calciphylaxis-related pain.Dose modification of ketamine is not required for patients with impaired renal function, and low dose intravenous ketamine infusion was associated with no reported adverse effects in our patient.

Antidepressant Actions of Ketamine: Potential Role of L-Type Calcium Channels

Recently, the United States Food and Drug Administration approved esketamine, the S-enantiomer of ketamine, as a fast-acting therapeutic drug for treatment-resistant depression. Although ketamine is known as an N-methyl-d-aspartate (NMDA) receptor antagonist, the underlying mechanisms of how it elicits an antidepressant effect, specifically at subanesthetic doses, are not clear and remain an advancing field of research interest. On the other hand, high-dose (more than the anesthetic dose) ketamine-induced neurotoxicity in animal models has been reported. There has been progress in understanding the potential pathways involved in ketamine-induced antidepressant effects, some of which include NMDA-receptor antagonism, modulation of voltage-gated calcium channels, and brain-derived neurotrophic factor (BDNF) signaling. Often these pathways have been shown to be linked. Voltage-gated L-type calcium channels have been shown to mediate the rapid-acting antidepressant effects of ketamine, especially involving induction of BDNF synthesis downstream, while BDNF deficiency decreases the expression of L-type calcium channels. This review focuses on the reported studies linking ketamine's rapid-acting antidepressant actions to L-type calcium channels with an objective to present a perspective on the importance of the modulation of intracellular calcium in mediating the effects of subanesthetic (antidepressant) versus high-dose ketamine (anesthetic and potential neurotoxicant), the latter having the ability to reduce intracellular calcium by blocking the calcium-permeable NMDA receptors, which is implicated in potential neurotoxicity.

Prolonged Ketamine and Norketamine Excretion Profiles in Urine After Chronic Use: A Case Series

PURPOSE/BACKGROUND

Ketamine (K) is used as a party drug with hallucinogenic properties with a half-life of about 2.5 hours. Data are available with respect to the detection window (ie, when a person is still tested positive for the drug and/or metabolite after use) of K after single use. Nevertheless, no data are available with respect to the detection window of K in urine after chronic use.

METHODS/PROCEDURES

This retrospective case series describes 7 patients with K dependency as their main addiction who have been admitted to an addiction center for K detoxification. Their abstinence-oriented care involved routine urinary screening of K and its metabolites, as well as traditional drugs of abuse, such as cocaine and cannabinoids.

FINDINGS/RESULTS

Urine samples remained positive for all the cases identified after 22 to 96 days. A peak detection period of 61, 40, and 96 days for K, norketamine, and dehydronorketamine, respectively, measured using liquid chromatography-tandem mass spectrometry at a cutoff concentration of 1.0 ng/mL, is defined. The K/norketamine and K/dehydronorketamine ratios varied over time between 0.33 and 3.06, and 0.01 and 0.36 for all patients, respectively, implying a large interindividual variation in K metabolism.

IMPLICATIONS/CONCLUSIONS

Ketamine and its metabolites have a prolonged excretion profile in urine, which requires frequent measurements (at least weekly) to guide abstinence treatment. Further research is needed to develop an algorithm that can differentiate new K use from residual urinary K excretion in urine of chronic daily users.

Advances in novel molecular targets for antidepressants

Depression is the most common psychiatric illness affecting numerous people world-wide. The currently available antidepressant treatment presents low response and remission rates. Thus, new effective antidepressants need to be developed or discovered. Aiming to give an overview of novel possible antidepressant drug targets, we summarized the molecular targets of antidepressants and the underlying neurobiology of depression. We have also addressed the multidimensional perspectives on the progress in the psychopharmacological treatment of depression and on the new potential approaches with effective drug discovery.

Online Enantioselective Capillary Electrophoretic Method for Screening Cytochrome P450 3A4 Inhibitors

The market share of single-enantiomer drugs is steadily increasing. The pharmacodynamics and pharmacokinetics of individual enantiomers can differ considerably. Thus, their characteristics have to be addressed as early as possible in the development process of new pharmaceuticals. Capillary electrophoresis is a promising technique for enantioselective drug metabolism studies due to highly effective separations, minuscule consumption of sample and reagents, compatibility with a variety of detection techniques, high-throughput via automation, and the implementation of online procedures. An online method comprised of the diffusion-based mixing of cytochrome P450 3A4 with racemic ketamine, incubation of the enzyme reaction, separation of the reaction products S- and R-norketamine, and their quantification is presented in this chapter. Since diffusion is an inherent property of all molecules, the method enables the addition of virtually any compound to the reaction mixture without the need for additional optimization of the mixing conditions, and thus can be favorably used for the rapid screening of putative cytochrome P450 3A4 inhibitors.

Repurposing of Drugs-The Ketamine Story

An intranasal formulation of esketamine, the S enantiomer of ketamine, in conjunction with an oral antidepressant, has been approved by the FDA for treating treatment-resistant major depressive disorder (TRD) in 2019, almost 50 years after it was approved as an intravenous anesthetic. In contrast to traditional antidepressants, ketamine shows a rapid (within 2 h) and sustained (∼7 days) antidepressant effect and has significant positive effects on antisuicidal ideation. Ketamine's antidepressant mechanism is predominantly mediated by the N-methyl-d-aspartate receptor (NMDA) receptor, although NMDA-independent mechanisms are not ruled out. At the neurocircuitry level, ketamine affects the brain's reward and mood circuitry located in the corticomesolimbic structures involving the hippocampus, nucleus accumbens, and prefrontal cortex. Repurposing of ketamine for treating TRD provided a new understanding of the pathophysiology of depression, a paradigm shift from monoamine to glutamatergic neurotransmission, thus making it a unique tool to investigate the brain and its complex neurocircuitries.

Ketamine to treat super-refractory status epilepticus

OBJECTIVE

To test ketamine infusion efficacy in the treatment of super-refractory status epilepticus (SRSE), we studied patients with SRSE who were treated with ketamine retrospectively. We also studied the effect of high doses of ketamine on brain physiology as reflected by invasive multimodality monitoring (MMM).

METHODS

We studied a consecutive series of 68 patients with SRSE who were admitted between 2009 and 2018, treated with ketamine, and monitored with scalp EEG. Eleven of these patients underwent MMM at the time of ketamine administration. We compared patients who had seizure cessation after ketamine initiation to those who did not.

RESULTS

Mean age was 53 ± 18 years and 46% of patients were female. Seizure burden decreased by at least 50% within 24 hours of starting ketamine in 55 (81%) patients, with complete cessation in 43 (63%). Average dose of ketamine infusion was 2.2 ± 1.8 mg/kg/h, with median duration of 2 (1-4) days. Average dose of midazolam was 1.0 ± 0.8 mg/kg/h at the time of ketamine initiation and was started at a median of 0.4 (0.1-1.0) days before ketamine. Using a generalized linear mixed effect model, ketamine was associated with stable mean arterial pressure (odds ratio 1.39, 95% confidence interval 1.38-1.40) and with decreased vasopressor requirements over time. We found no effect on intracranial pressure, cerebral blood flow, or cerebral perfusion pressure.

CONCLUSION

Ketamine treatment was associated with a decrease in seizure burden in patients with SRSE. Our data support the notion that high-dose ketamine infusions are associated with decreased vasopressor requirements without increased intracranial pressure.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that ketamine decreases seizures in patients with SRSE.

Comparative Study of Retrobulbar Block versus Ketamine Infusion during Eye Enucleation/Evisceration (Randomized Controlled Trial)

Background

The aim of this study is to compare the safety and efficacy of retrobulbar block versus intraoperative ketamine infusion in eye enucleation or evisceration under general anesthesia.

Materials and Methods

Forty-five patients belonging to American Society of Anesthesiologists Physical Status I and II undergoing eye enucleation or evisceration were randomly allocated to three equal groups (15 patients each). General anesthesia was used as the standardized technique in all patients. Group R received a single retrobulbar injection, Group K received intravenous ketamine infusion, and Group C received normal saline with the same rate of ketamine infusion. Intraoperative heart rate and mean arterial pressure, recovery time, postoperative pain score, time to first rescue analgesic, number of patients who required rescue analgesia, and any adverse events were reported.

Results

Postoperative pain Visual Analog Scale was significantly lower in R and K groups in comparison to the C group and was significantly higher in K than R group at 3, 6, 12, and 24 h. In addition, the time to first rescue analgesic was significantly longer in R group (429 ± 54 min) than that in K group (272 ± 34 min), but compared to both groups, it was longer in C group (52 ± 7 min). In K group, the recovery time was longer with higher sedation score in comparison to the other two groups.

Conclusions

Single retrobulbar injection and low-dose ketamine infusion are safe and effective when used as adjuvants to general anesthesia, but retrobulbar block provides better control of postoperative pain with prolonged time to first rescue analgesic and reduced analgesic consumption.

Ketamine induces rapid and sustained antidepressant-like effects in chronic pain induced depression: Role of MAPK signaling pathway

Chronic pain produces psychologic distress, which often leads to mood disorders such as depression. Co-existing chronic pain and depression pose a serious socio-economic burden and result in disability affecting millions of individuals, which urges the development of treatment strategies targeting this comorbidity. Ketamine, a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) receptor, is shown to be efficient in treating both pain and depression-related symptoms. However, the molecular characteristics of its role in chronic pain-induced depression remain largely unexplored. Hence, we studied the behavioral and molecular effects of a single systemic administration of ketamine (15 mg/kg, i.p.) on mechanical hypersensitivity and depressive-like consequences of chronic neuropathic pain. We showed that ketamine transiently alleviated mechanical hypersensitivity (lasting <24 h), while its antidepressant effect was observed even 72 h after administration. In addition, ketamine normalized the upregulated expression of the mitogen activated protein kinase (MAPK) phosphatase 1 (MKP-1) and the downregulated phosphorylation of extracellular signal-regulated kinase (pERK) in the anterior cingulate cortex (ACC) of mice displaying neuropathic pain-induced depressive-like behaviors. This effect of ketamine on the MKP-1 was first detected 30 min after the ketamine administration and persisted until up to 72 h. Altogether, these findings provide insight into the behavioral and molecular changes associated with single ketamine administration in the comorbidity of chronic pain and depression.

Different Effects of Volatile and Nonvolatile Anesthetic Agents on Long-Term Survival in an Experimental Model of Hemorrhagic Shock

BACKGROUND

We investigated whether the cardioprotective, volatile gas anesthetic agent, isoflurane, could improve survival and organ function from hemorrhagic shock in an experimental rat model, compared to standard nonvolatile anesthetic agent ketamine/xylazine.

METHODS

Sprague Dawley rats (both genders) were randomized to receive either intraperitoneal ketamine/xylazine (K/X, 90 and 10 mg/kg; n = 12) or isoflurane (5% isoflurane induction and 2% maintenance in room air; n = 12) for anesthesia. Blood was withdrawn to maintain mean arterial blood pressure at 30 mm Hg for 1 hour, followed by 30 minutes of resuscitation with shed blood. Rats were allowed to recover and survive for 6 weeks.

RESULTS

During the shock phase, the total withdrawn blood volume (expressed as % of estimated total blood volume) to maintain a level of hypotension of 30 mm Hg was significantly higher in the isoflurane group (51.0% ± 1.5%) than in the K/X group (45.3% ± 1.8%; P = .023). Recovery of blood pressure during the resuscitation phase was significantly improved in the isoflurane group compared to the K/X group. The survival rate at 6 weeks was 1 (8.3%) of 12 in rats receiving K/X and 10 (83.3%) of 12 in rats receiving isoflurane (P < .001). Histology performed at 6 weeks demonstrated brain infarction in the 1 surviving rat receiving K/X; no brain infarction occurred in the 10 surviving rats that received isoflurane. No infarction was detected in heart, lung, liver, or kidneys among the surviving rats.

CONCLUSIONS

Isoflurane improved blood pressure response to resuscitation and resulted in significantly higher long-term survival rate.

Acute postoperative pain management

Background

Acute postoperative pain is common. Nearly 20 per cent of patients experience severe pain in the first 24 h after surgery, a figure that has remained largely unchanged in the past 30 years. This review aims to present key considerations for postoperative pain management.

Methods

A narrative review of postoperative pain strategies was undertaken. Searches of the Cochrane Library, PubMed and Google Scholar databases were performed using the terms postoperative care, psychological factor, pain management, acute pain service, analgesia, acute pain and pain assessment.

Results

Information on service provision, preoperative planning, pain assessment, and pharmacological and non-pharmacological strategies relevant to acute postoperative pain management in adults is presented, with a focus on enhanced recovery after surgery pathways.

Conclusion

Adequate perioperative pain management is integral to patient care and outcomes. Each of the biological, psychological and social dimensions of the pain experience should be considered and understood in order to provide optimum pain management in the postoperative setting.

Negative results for ketamine use in severe acute bronchospasm: a randomised controlled trial

BACKGROUND

Ketamine has bronchodilation properties. The aim of the single-centre, evaluator-blinded, randomised clinical trial study was to evaluate whether continuous infusion of ketamine is associated with improvement in respiratory mechanics correlated with bronchospasm relief, as compared with continuous infusion of fentanyl.

METHODS

Adult patients submitted to invasive mechanical ventilation were included if they had an acute severe bronchospasm, due to status asthmaticus or COPD exacerbation. They were randomised to ketamine or a standard IV analgesia with fentanyl, both in bolus and continuous infusion. Measurements of respiratory mechanics (airway resistance - Rsmax, dynamic compliance - Cdyn and intrinsic PEEP - PEEPi) both at baseline and 3 and 24 h after randomisation were performed. The main outcome of this study was to evaluate the improvement of Rsmax in 3 h of continuous infusion of the study drugs.

RESULTS

Ketamine use was not associated with greater reduction in Rsmax when compared with fentanyl, either after 3 h (0 cm H2O L-1 s-1 ± 6 vs. -3 cm H2O L-1 s-1 ± 7.7, respectively; P = 0.16) or after 24 h (-3 cm H2O L-1 s-1 ± 17 vs. -3.5 cm H2O L-1 s-1 ± 13.7, respectively; P = 0.73). Patients randomized to the ketamine group did not have better improvements in delta PEEPi as compared with fentanyl in 3 h (P = 0.77) or in 24 h (P = 0.72).

CONCLUSIONS

In this study, ketamine use was not associated with improvement in ventilatory variables associated with bronchospasm.

Efficacy and safety of prophylactic use of ketamine for prevention of postanesthetic shivering: a systematic review and meta analysis

Background

Postanesthetic shivering is a common complication of anesthesia, which accounts for much discomfort in postoperative patients and may increase postoperative complications in high-risk patients. Due to the lack of high-quality evidence, it is difficult to draw a conclusion about optimal anti-shivering medication. The main purpose of this meta-analysis was to analyze and evaluate the efficacy and safety of prophylactic use of ketamine for preventing postanesthetic shivering.

Methods

We searched the following databases: Medline, Embase, and the Cochrane Central Register of Controlled Trails for randomized controlled trials. The primary outcome observed was the difference of the incidence rate of postanesthetic shivering between ketamine group and placebo group. The secondary outcomes were the sedation score and incidence of the side effects caused by ketamine and any other drugs utilized in the studies.

Results

In this meta-analysis, we analyzed a total of 16 trials including 1485 patients. Ketamine reduced the incidence rate of postanesthetic shivering compared to a placebo (odds ratio [OR]: 0.13, 95% confidence interval [CI]: 0.06 to 0.26, P<0.01). Regarding side effects, there was no evident variability of the incidence of nausea and vomiting. Usage of ketamine was associated with a lower rate of hypotension and bradycardia when compared to a placebo. Hallucinations were more frequently observed in patients who received higher doses of ketamine. No significant difference was found in the incidence of postanesthetic shivering with ketamine versus other pharmacological interventions.

Conclusions

Ketamine can prevent postanesthetic shivering without severe side effects. However, ketamine shows no advantage over other anti-shivering drugs.

[Drugs for intravenous induction of anesthesia: ketamine, midazolam and synopsis of current hypnotics]

Ketamine and midazolam form the endpoint of a series of articles about intravenous induction of anesthesia . Both substances can be used as single induction hypnotic drugs; however, in practice, this is unusual. Both substances, with the exception of a few very specific indications and clinical situations, are more frequently used in combination or with one of the more common alternatives propofol, barbiturates and etomidate. The reasons are the activity and side effects of both substances and their positive characteristics are used more as a supplement. In the concluding comparison the five discussed induction hypnotics are judged against each other. The use in certain clinical constellations and in special patient populations is evaluated individually for each substance. It is highlighted which drug appears most appropriate in which situation. As methohexital is nowadays only administered in very few clinical situations, this substance is not included in the comparative assessment.

Oral esketamine for treatment-resistant depression: rationale and design of a randomized controlled trial

BACKGROUND

There is an urgent need to develop additional treatment strategies for patients with treatment-resistant depression (TRD). The rapid but short-lived antidepressant effects of intravenous (IV) ketamine as a racemic mixture have been shown repeatedly in this population, but there is still a paucity of data on the efficacy and safety of (a) different routes of administration, and (b) ketamine's enantiomers esketamine and arketamine. Given practical advantages of oral over IV administration and pharmacodynamic arguments for better antidepressant efficacy of esketamine over arketamine, we designed a study to investigate repeated administration of oral esketamine in patients with TRD.

METHODS

This study features a triple-blind randomized placebo-controlled trial (RCT) comparing daily oral esketamine versus placebo as add-on to regular antidepressant medications for a period of 6 weeks, succeeded by a follow-up of 4 weeks. The methods support examination of the efficacy, safety, tolerability, mechanisms of action, and economic impact of oral esketamine in patients with TRD.

DISCUSSION

This is the first RCT investigating repeated oral esketamine administration in patients with TRD. If shown to be effective and tolerated, oral esketamine administration poses important advantages over IV administration.

TRIAL REGISTRATION

Dutch Trial Register, NTR6161. Registered 21 October 2016.

Expanding Role of NMDA Receptor Antagonists in the Management of Pain

Pain management is complex regardless of whether the pain is acute or chronic in nature or non-cancer or cancer related. In addition, relatively few pain pharmacotherapy options with adequate efficacy and safety data currently exist. Consequently, interest in the role of NMDA receptor antagonists as a pharmacological pain management strategy has surfaced. This narrative review provides an overview of the NMDA receptor and elaborates on the pharmacotherapeutic profile and pain management literature findings for the following NMDA receptor antagonists: ketamine, memantine, dextromethorphan, and magnesium. The literature on this topic is characterized by small studies, many of which exhibit methodological flaws. To date, ketamine is the most studied NMDA receptor antagonist for both acute and chronic pain management. Although further research about NMDA receptor antagonists for analgesia is needed and the optimal dosage/administration regimens for these drugs have yet to be determined, ketamine appears to hold the most promise and may be of particular value in the perioperative pain management realm.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.

In search of a longitudinal animal model of evoked swallow function

Background

A malfunction or impairment of swallow function can potentiate aspiration events and interfere with both quality of life and survival. Establishing an animal model for swallow research would provide a better understanding of its pathophysiology and would also allow for the development and validation of physiologically based clinical interventions to improve swallow function. Two requirements define the ideal model for longitudinal exploration: 1) identification of species similar to human in form and function; and 2) provision for reliable and reproducible evoked swallow under general anesthesia and one that would also support a longitudinal study design.

Objective

We hypothesize that an anesthetized porcine model under dexmedetomidine-based or ketamine-based anesthesia will support a reproducible and stable evoked swallow response.

Methods

Seven neutered male Yorkshire pigs were anesthetized using combinations of dexmedetomidine-based or ketamine-based anesthesia for induction and maintenance of anesthesia during the experimental portion of our study. Single stimulation of iSLN or vagus nerve, bilateral simultaneous single stimulation of iSLN or vagus nerve, and stimulus trains applied to afferent nerves were performed.

Results

None of the seven pigs demonstrated evoked swallow events, both during inhalational anesthesia (1.0 MAC) or during post-washout intravenous anesthesia (dexmedetomidine, ketamine/fentanyl or ketamine alone).

Conclusion

Our results support a high degree of organizational neurophysiologic complexity characterizing the swallow reflex and highlight the challenges and limitations of intraoperative study in survival models.

Level of Evidence

NA Laryngoscope, 2018.

Efficacy of prophylactic epidural ketamine for reducing shivering in patients undergoing caesarean section with combined spinal-epidural anesthesia

Intravenous ketamine is known to inhibit postoperative shivering; however, at present, there has been little research on whether this effect may be achieved with epidural application. The aim of the present study was to evaluate the efficacy and safety of epidural ketamine as a prophylactic agent to prevent shivering in patients undergoing caesarean section during combined spinal-epidural anesthesia. A prospective, randomized, double-blind study was performed. A total of 60 patients who were undergoing elective caesarean section under combined spinal-epidural anesthesia and had an American Society of Anesthesiologists physical status of I or II were recruited. Patients were randomly allocated to group S (epidural administration of normal saline; n=30) or group K (epidural ketamine 0.5 mg/kg; n=30). An investigator, blinded to the treatment groups, graded postoperative shivering using a 4-point scale and postoperative sedation on a 5-point scale. Operative time, hemodynamic changes and side effects, including hypotension, bradycardia, nausea and hallucinations, were recorded. The results demonstrated that patients' characteristics were not significantly different between groups. Heart rate, peripheral capillary oxygen saturation (SpO₂) values and Apgar scores at 1 and 5 min also did not differ significantly between groups. The incidence and severity of shivering in group K was significantly reduced compared with group S (P<0.05). The mean arterial pressure (MAP) was significantly different in groups S and K compared with baseline values at 10, 30 and 60 min (P<0.05). Furthermore, MAP values at 10, 30 and 60 min were significantly higher in group K compared with in group S (P<0.05). The results of the present study suggest that epidural administration of prophylactic low-dose ketamine may be an effective strategy for preventing postoperative shivering.

Effects of Ketamine on Basal Gamma Band Oscillation and Sensory Gating in Prefrontal Cortex of Awake Rats

Gamma band oscillation (GBO) and sensory gating (SG) are associated with many cognitive functions. Ketamine induces deficits of GBO and SG in the prefrontal cortex (PFC). However, the time-courses of the effects of different doses of ketamine on GBO power and SG are poorly understood. Studies have indicated that GBO power and SG have a common substrate for their generation and abnormalities. In this study, we found that (1) ketamine administration increased GBO power in the PFC in rats differently in the low- and high-dose groups; (2) auditory SG was significantly lower than baseline in the 30 mg/kg and 60 mg/kg groups, but not in the 15 mg/kg and 120 mg/kg groups; and (3) changes in SG and basal GBO power were significantly correlated in awake rats. These results indicate a relationship between mechanisms underlying auditory SG and GBO power.