The Ketamine Effect on ICP in Traumatic Brain Injury

Effect of volatile anaesthetic agents on intracranial pressure, cerebrovascular flow and autoregulation: a protocol for a systematic review and meta-analysis

INTRODUCTION

The use of volatile anaesthetic agents for the sedation of patients requiring critical care treatment offers several theoretical advantages over intravenous sedation, which may be of benefit in neurocritical care. However, there are concerns that they may increase intracranial pressure. The objective of this systematic review is to assess whether, and if so, to what extent volatile anaesthetic agents affect intracranial pressure, cerebral blood flow (CBF), cerebral oximetry and cerebrovascular autoregulation. If sufficient data exist, subgroup analyses will be conducted in traumatic brain injury and decompressive craniectomy patients.

METHODS AND ANALYSIS

A database search of PubMed, Medline (including Medline plus), CINAHL (including CINAHL Plus), Embase databases and the Cochrane Central Controlled Trials Register without time limits will be conducted. The search results will be screened by title and abstract by two independent researchers on a rule-in basis against predetermined criteria-controlled studies in humans of contemporary fluorinated volatile anaesthetic agents against a control, which measures intracranial pressure, CBF, cerebral oximetry or cerebrovascular autoregulation. Articles responsive to screening will then be reviewed in full text by two independent researchers, requiring consensus or a tie-break by a third independent researcher. Reference lists and a non-generative AI tool will be examined for missed articles, with all identified articles being reviewed in full text by two independent researchers. The included articles will be assessed for risk of bias and will have data extracted by two independent researchers. If sufficient data exist, a meta-analysis will be performed; otherwise, a narrative description of outcomes will be performed.

ETHICS AND DISSEMINATION

No ethics approval will be sought for this systematic review. This study has no explicit funding. The results of this study will be disseminated in a peer-reviewed journal, in a conference presentation and on PROSPERO.

TRIAL REGISTRATION NUMBER

PROSPERO number CRD42023474587.

Ketamine Analgo-sedation for Mechanically Ventilated Critically Ill Adults: A Rapid Practice Guideline from the Saudi Critical Care Society and the Scandinavian Society of Anesthesiology and Intensive Care Medicine

BACKGROUND

This Rapid Practice Guideline (RPG) aimed to provide evidence‑based recommendations for ketamine analgo-sedation (monotherapy and adjunct) versus non-ketamine sedatives or usual care in adult intensive care unit (ICU) patients on invasive mechanical ventilation (iMV) and to identify knowledge gaps for future research.

METHODS

The RPG panel comprised 23 multinational multidisciplinary panelists, including a patient representative. An up-to-date systematic review and meta-analysis constituted the evidence base. The Grading Recommendations, Assessment, Development, and Evaluation approach, and the evidence-to-decision framework were used to assess the certainty of evidence and to move from evidence to decision/recommendation. The panel provided input on the balance of the desirable and undesirable effects, certainty of evidence, patients' values and preferences, costs, resources, equity, feasibility, acceptability, and research priorities.

RESULTS

Data from 17 randomized clinical trials (n=898) and 9 observational studies (n=1934) were included. There was considerable uncertainty about the desirable and undesirable effects of ketamine monotherapy for analgo-sedation. The evidence was very low certainty and downgraded for risk of bias, indirectness, and inconsistency. Uncertainty or variability in values and preferences were identified. Costs, resources, equity, and acceptability were considered varied. Adjunctive ketamine therapy had no effect on mortality (within 28 days) (relative risk [RR] 0.99; 95% confidence interval [CI] 0.76 to 1.27; low certainty), and may slightly reduce iMV duration (days) (mean difference [MD] -0.05 days; 95% CI -0.07 to -0.03; low certainty), and uncertain effect on the cumulative dose of opioids (mcg/kg/h morphine equivalent) (MD -11.6; 95% CI -20.4 to -2.7; very low certainty). Uncertain desirable effects (cumulative dose of sedatives and vasopressors) and undesirable effects (adverse event rate, delirium, arrhythmia, hepatotoxicity, hypersalivation, use of physical restraints) were also identified. A possibility of important uncertainty or variability in patient-important outcomes led to a balanced effect that favored neither the intervention nor the comparison. Cost, resources, and equity were considered varied.

CONCLUSION

The RPG panel provided two conditional recommendations and suggested (1) against using ketamine as monotherapy analgo-sedation in critically ill adults on iMV when other analgo-sedatives are available; and (2) using ketamine as an adjunct to non-ketamine usual care sedatives (e.g., opioids, propofol, dexmedetomidine) or continuing with non-ketamine usual care sedatives alone. Large-scale trials should provide additional evidence.

Ketamine analgo-sedation for mechanically ventilated critically ill adults: A rapid practice guideline from the Saudi Critical Care Society and the Scandinavian Society of Anesthesiology and Intensive Care Medicine

BACKGROUND

This Rapid Practice Guideline (RPG) aimed to provide evidence-based recommendations for ketamine analgo-sedation (monotherapy and adjunct) versus non-ketamine sedatives or usual care in adult intensive care unit (ICU) patients on invasive mechanical ventilation (iMV) and to identify knowledge gaps for future research.

METHODS

The RPG panel comprised 23 multinational multidisciplinary panelists, including a patient representative. An up-to-date systematic review and meta-analysis constituted the evidence base. The Grading Recommendations, Assessment, Development, and Evaluation approach, and the evidence-to-decision framework were used to assess the certainty of evidence and to move from evidence to decision/recommendation. The panel provided input on the balance of the desirable and undesirable effects, certainty of evidence, patients' values and preferences, costs, resources, equity, feasibility, acceptability, and research priorities.

RESULTS

Data from 17 randomized clinical trials (n = 898) and nine observational studies (n = 1934) were included. There was considerable uncertainty about the desirable and undesirable effects of ketamine monotherapy for analgo-sedation. The evidence was very low certainty and downgraded for risk of bias, indirectness, and inconsistency. Uncertainty or variability in values and preferences were identified. Costs, resources, equity, and acceptability were considered varied. Adjunctive ketamine therapy had no effect on mortality (within 28 days) (relative risk [RR] 0.99; 95% confidence interval [CI] 0.76 to 1.27; low certainty), and may slightly reduce iMV duration (days) (mean difference [MD] -0.05 days; 95% CI -0.07 to -0.03; low certainty), and uncertain effect on the cumulative dose of opioids (mcg/kg/h morphine equivalent) (MD -11.6; 95% CI -20.4 to -2.7; very low certainty). Uncertain desirable effects (cumulative dose of sedatives and vasopressors) and undesirable effects (adverse event rate, delirium, arrhythmia, hepatotoxicity, hypersalivation, use of physical restraints) were also identified. A possibility of important uncertainty or variability in patient-important outcomes led to a balanced effect that favored neither the intervention nor the comparison. Cost, resources, and equity were considered varied.

CONCLUSION

The RPG panel provided two conditional recommendations and suggested (1) against using ketamine as monotherapy analgo-sedation in critically ill adults on iMV when other analgo-sedatives are available; and (2) using ketamine as an adjunct to non-ketamine usual care sedatives (e.g., opioids, propofol, dexmedetomidine) or continuing with non-ketamine usual care sedatives alone. Large-scale trials should provide additional evidence.

Ketamine for Critically Ill Patients with Severe Acute Brain Injury: A Systematic Review with Meta-analysis and Trial Sequential Analysis of Randomized Clinical Trials

BACKGROUND

Patients with severe acute brain injury have a high risk of a poor clinical outcome due to primary and secondary brain injury. Ketamine reportedly inhibits cortical spreading depolarization, an electrophysiological phenomenon that has been associated with secondary brain injury, making ketamine potentially attractive for patients with severe acute brain injury. The aim of this systematic review is to explore the current literature regarding ketamine for patients with severe acute brain injury.

METHODS

We systematically searched international databases for randomized clinical trials comparing ketamine by any regimen versus placebo, no intervention, or any control drug for patients with severe acute brain injury. Two authors independently reviewed and selected trials for inclusion, extracted data, assessed risk of bias, and performed analysis using Review Manager and Trial Sequential Analysis. Evidence certainty was assessed using Grading of Recommendations Assessment, Development and Evaluation. The primary outcomes were the proportion of participants with an unfavorable functional outcome, the proportion of participants with one or more serious adverse events, and quality of life.

RESULTS

We identified five randomized trials comparing ketamine versus sufentanil, fentanyl, other sedatives, or saline (total N = 149 participants). All outcomes were at overall high risk of bias. The proportions of participants with one or more serious adverse events did not differ between ketamine and sufentanil or fentanyl (relative risk 1.45, 95% confidence interval 0.81-2.58; very low certainty). Trial sequential analysis showed that further trials are needed.

CONCLUSIONS

The level of evidence regarding the effects of ketamine on functional outcome and serious adverse events in patients with severe acute brain injury is very low. Ketamine may markedly, modestly, or not at all affect these outcomes. Large randomized clinical trials at low risk of bias are needed.

[Current Aspects of Intensive Medical Care for Traumatic Brain Injury - Part 1 - Primary Treatment Strategies, Haemodynamic Management and Multimodal Monitoring]

This two-part article deals with the intensive medical care of traumatic brain injury. Part 1 addresses the primary treatment strategy, haemodynamic management and multimodal monitoring, Part 2 secondary treatment strategies, long-term outcome, neuroprognostics and chronification. Traumatic brain injury is a complex clinical entity with a high mortality rate. The primary aim is to maintain homeostasis based on physiological targeted values. In addition, further therapy must be geared towards intracranial pressure. In addition to this, there are other monitoring options that appear sensible from a pathophysiological point of view with appropriate therapy adjustment. However, there is still a lack of data on their effectiveness. A further aspect is the inflammation of the cerebrum with the "cross-talk" of the organs, which has a significant influence on further intensive medical care.

Interleaved Propofol-Ketamine Maintains DBS Physiology and Hemodynamic Stability: A Double-Blind Randomized Controlled Trial

BACKGROUND

The gold standard anesthesia for deep brain stimulation (DBS) surgery is the "awake" approach, using local anesthesia alone. Although it offers high-quality microelectrode recordings and therapeutic-window assessment, it potentially causes patients extreme stress and might result in suboptimal surgical outcomes. General anesthesia or deep sedation is an alternative, but may reduce physiological testing reliability and lead localization accuracy.

OBJECTIVES

The aim is to investigate a novel anesthesia regimen of ketamine-induced conscious sedation for the physiological testing phase of DBS surgery.

METHODS

Parkinson's patients undergoing subthalamic DBS surgery were randomly divided into experimental and control groups. During physiological testing, the groups received 0.25 mg/kg/h ketamine infusion and normal saline, respectively. Both groups had moderate propofol sedation before and after physiological testing. The primary outcome was recording quality. Secondary outcomes included hemodynamic stability, lead accuracy, motor and cognitive outcome, patient satisfaction, and adverse events.

RESULTS

Thirty patients, 15 from each group, were included. Intraoperatively, the electrophysiological signature and lead localization were similar under ketamine and saline. Tremor amplitude was slightly lower under ketamine. Postoperatively, patients in the ketamine group reported significantly higher satisfaction with anesthesia. The improvement in Unified Parkinson's disease rating scale part-III was similar between the groups. No negative effects of ketamine on hemodynamic stability or cognition were reported perioperatively.

CONCLUSIONS

Ketamine-induced conscious sedation provided high quality microelectrode recordings comparable with awake conditions. Additionally, it seems to allow superior patient satisfaction and hemodynamic stability, while maintaining similar post-operative outcomes. Therefore, it holds promise as a novel alternative anesthetic regimen for DBS. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Etomidate versus Ketamine as Prehospital Induction Agent in Patients with Suspected Severe Traumatic Brain Injury

BACKGROUND

Severe traumatic brain injury is a leading cause of morbidity and mortality among young people around the world. Prehospital care focuses on the prevention and treatment of secondary brain injury and commonly includes tracheal intubation after induction of general anesthesia. The choice of induction agent in this setting is controversial. This study therefore investigated the association between the chosen induction medication etomidate versus S(+)-ketamine and the 30-day mortality in patients with severe traumatic brain injury who received prehospital airway management in the Netherlands.

METHODS

This study is a retrospective analysis of the prospectively collected observational data of the Brain Injury: Prehospital Registry of Outcomes, Treatments and Epidemiology of Cerebral Trauma (BRAIN-PROTECT) cohort study. Patients with suspected severe traumatic brain injury who were transported to a participating trauma center and who received etomidate or S(+)-ketamine for prehospital induction of anesthesia for advanced airway management were included. Statistical analyses were performed with multivariable logistic regression and inverse probability of treatment weighting analysis.

RESULTS

In total, 1,457 patients were eligible for analysis. No significant association between the administered induction medication and 30-day mortality was observed in unadjusted analyses (32.9% mortality for etomidate versus 33.8% mortality for S(+)-ketamine; P = 0.716; odds ratio, 1.04; 95% CI, 0.83 to 1.32; P = 0.711), as well as after adjustment for potential confounders (odds ratio, 1.08; 95% CI, 0.67 to 1.73; P = 0.765; and risk difference 0.017; 95% CI, -0.051 to 0.084; P = 0.686). Likewise, in planned subgroup analyses for patients with confirmed traumatic brain injury and patients with isolated traumatic brain injury, no significant differences were found. Consistent results were found after multiple imputations of missing data.

CONCLUSIONS

The analysis found no evidence for an association between the use of etomidate or S(+)-ketamine as an anesthetic agent for intubation in patients with traumatic brain injury and mortality after 30 days in the prehospital setting, suggesting that the choice of induction agent may not influence the patient mortality rate in this population.

EDITOR’S PERSPECTIVE

Ketamine in Chronic Pain: A Review

Ketamine has been used in the treatment of several pain syndromes, particularly those with a relevant neuropathic component. Sub-anesthetic doses of ketamine produce a potent analgesic effect, due to its inhibition of N-methyl-D-aspartate receptors and enhancement of descending inhibitory pathways. Its short-term analgesic effect is well-documented perioperatively, with an associated reduction in postoperative chronic pain and opioid consumption. Despite some evidence regarding its long-term benefits, the number of clinical studies is still limited. In addition to its analgesic effects, ketamine also possesses an anti-depressive action, which might be useful in the treatment of chronic pain patients. Several side effects have been described, the psychomimetic ones being the most relevant due to their impact on treatment adhesion. At present, co-administration of ketamine and benzodiazepines or α2-agonists facilitates its clinical application. Despite current evidence and increasing use, further investigation is still needed regarding its long-term safety profile and clearer risk-benefit analysis.

The impact of ketamine on outcomes in critically ill patients: a systematic review with meta-analysis and trial sequential analysis of randomized controlled trials

BACKGROUND

This meta-analysis aims to evaluate the effects of ketamine in critically ill intensive care unit (ICU) patients.

METHODS

We searched for randomized controlled trials (RCTs) in PubMed, Scopus, and the Cochrane Library; the search was performed initially in January but was repeated in December of 2023. We focused on ICU patients of any age. We included studies that compared ketamine with other traditional agents used in the ICU. We synthesized evidence using RevMan v5.4 and presented the results as forest plots. We also used trial sequential analysis (TSA) software v. 0.9.5.10 Beta and presented results as TSA plots. For synthesizing results, we used a random-effects model and reported differences in outcomes of two groups in terms of mean difference (MD), standardized MD, and risk ratio with 95% confidence interval. We assessed the risk of bias using the Cochrane RoB tool for RCTs. Our outcomes were mortality, pain, opioid and midazolam requirements, delirium rates, and ICU length of stay.

RESULTS

Twelve RCTs involving 805 ICU patients (ketamine group, n=398; control group, n=407) were included in the meta-analysis. The ketamine group was not superior to the control group in terms of mortality (in five studies with 318 patients), pain (two studies with 129 patients), mean and cumulative opioid consumption (six studies with 494 patients), midazolam consumption (six studies with 304 patients), and ICU length of stay (three studies with 270 patients). However, the model favored the ketamine group over the control group in delirium rate (four studies with 358 patients). This result is significant in terms of conventional boundaries (alpha=5%) but is not robust in sequential analysis. The applicability of the findings is limited by the small number of patients pooled for each outcome.

CONCLUSIONS

Our meta-analysis did not demonstrate differences between ketamine and control groups regarding any outcome except delirium rate, where the model favored the ketamine group over the control group. However, this result is not robust as sensitivity analysis and trial sequential analysis suggest that more RCTs should be conducted in the future.

Broadening horizons: ferroptosis as a new target for traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, with ~50 million people experiencing TBI each year. Ferroptosis, a form of regulated cell death triggered by iron ion-catalyzed and reactive oxygen species-induced lipid peroxidation, has been identified as a potential contributor to traumatic central nervous system conditions, suggesting its involvement in the pathogenesis of TBI. Alterations in iron metabolism play a crucial role in secondary injury following TBI. This study aimed to explore the role of ferroptosis in TBI, focusing on iron metabolism disorders, lipid metabolism disorders and the regulatory axis of system Xc-/glutathione/glutathione peroxidase 4 in TBI. Additionally, we examined the involvement of ferroptosis in the chronic TBI stage. Based on these findings, we discuss potential therapeutic interventions targeting ferroptosis after TBI. In conclusion, this review provides novel insights into the pathology of TBI and proposes potential therapeutic targets.

Ketamine as adjunctive or monotherapy for post-intubation sedation in patients with trauma on mechanical ventilation: A rapid review

Background

The effectiveness of ketamine as adjunctive or monotherapy for post-intubation sedation in adults with trauma on mechanical ventilation is unclear.

Methods

A rapid review of systematic reviews of randomized controlled trials, then randomized controlled trials or observational studies was conducted searching three electronic databases (PubMed, Embase, Cochrane Library) and one clinical trial registry on June 1, 2022. We used a prespecified protocol following Cochrane rapid review methods.

Results

We identified eight systematic reviews of randomized controlled trials and observational studies. Among the included reviews, only the most relevant, up to date, highest quality-assessed reviews and reviews that reported on critical outcomes were considered. Adjunctive ketamine showed a morphine sparing effect (MD -13.19 µmg kg-1 h-1, 95 % CI -22.10 to -4.28, moderate certainty of evidence, 6 RCTs), but no to little effect on midazolam sparing effect (MD 0.75 µmg kg-1 h-1, 95 % CI -1.11 to 2.61, low certainty of evidence, 6 RCTs) or duration of mechanical ventilation in days (MD -0.17 days, 95 % CI -3.03 to 2.69, moderate certainty of evidence, 3 RCTs).Adjunctive ketamine therapy may reduce mortality (OR 0.88, 95 % CI 0.54 to 1.43, P = 0.60, very low certainty of evidence, 5 RCTs, n = 3076 patients) resulting in 30 fewer deaths per 1000, ranging from 132 fewer to 87 more, but the evidence is very uncertain. Ketamine results in little to no difference in length of ICU stay (MD 0.04 days, 95 % CI -0.12 to 0.20, high certainty of evidence, 5 RCTs n = 390 patients) or length of hospital stay (MD -0.53 days, 95 % CI -1.36 to 0.30, high certainty of evidence, 5 RCTs, n = 277 patients).Monotherapy may have a positive effect on respiratory and haemodynamic outcomes, however the evidence is very uncertain.

Conclusion

Adjunctive ketamine for post-intubation analgosedation results in a moderate meaningful net benefit but there is uncertainty for benefit and harms as monotherapy.

The Effect of Ketamine Versus Etomidate for Rapid Sequence Intubation on Maximum Sequential Organ Failure Assessment Score: A Randomized Clinical Trial

BACKGROUND

The use of induction agents for rapid sequence intubation (RSI) has been associated with hypotension in critically ill patients. Choice of induction agent may be important and the most commonly used agents are etomidate and ketamine.

OBJECTIVE

This study aimed to compare the effects of a single dose of ketamine vs. etomidate for RSI on maximum Sequential Organ Failure Assessment (SOFA) score and incidence of hypotension.

METHODS

This single-center, randomized, parallel-group trial compared the use of ketamine and etomidate for RSI in critically ill adult patients in the emergency department. The study was performed under Exception from Informed Consent. The primary outcome was the maximum SOFA score within 3 days of hospitalization.

RESULTS

A total of 143 patients were enrolled in the trial, 70 in the ketamine group and 73 in the etomidate group. Maximum median SOFA score for the ketamine group was 6.5 (interquartile range [IQR] 5-9) vs. 7 (IQR 5-9) for etomidate with no significant difference (-0.2; 95% CI -1.4 to 1.1; p = 0.79). The incidence of post-intubation hypotension was 28% in the ketamine group vs. 26% in the etomidate group (difference 2%; 95% CI -13% to 17%). There were no significant differences in intensive care unit outcomes. Thirty-day mortality rate for the ketamine group was 11% (8 deaths) and for the etomidate group was 21% (15 deaths), which was not statistically different.

CONCLUSIONS

There were no significant differences in maximum SOFA score or post-intubation hypotension between critically ill adults receiving ketamine vs. etomidate for RSI.

Systemic inflammation induced from remote extremity trauma is a critical driver of secondary brain injury

Blast exposure, commonly experienced by military personnel, can cause devastating life-threatening polysystem trauma. Despite considerable research efforts, the impact of the systemic inflammatory response after major trauma on secondary brain injury-inflammation is largely unknown. The aim of this study was to identify markers underlying the susceptibility and early onset of neuroinflammation in three rat trauma models: (1) blast overpressure exposure (BOP), (2) complex extremity trauma (CET) involving femur fracture, crush injury, tourniquet-induced ischemia, and transfemoral amputation through the fracture site, and (3) BOP+CET. Six hours post-injury, intact brains were harvested and dissected to obtain biopsies from the prefrontal cortex, striatum, neocortex, hippocampus, amygdala, thalamus, hypothalamus, and cerebellum. Custom low-density microarray datasets were used to identify, interpret and visualize genes significant (p < 0.05 for differential expression [DEGs]; 86 neuroinflammation-associated) using a custom python-based computer program, principal component analysis, heatmaps and volcano plots. Gene set and pathway enrichment analyses of the DEGs was performed using R and STRING for protein-protein interaction (PPI) to identify and explore key genes and signaling networks. Transcript profiles were similar across all regions in naïve brains with similar expression levels involving neurotransmission and transcription functions and undetectable to low-levels of inflammation-related mediators. Trauma-induced neuroinflammation across all anatomical brain regions correlated with injury severity (BOP+CET > CET > BOP). The most pronounced differences in neuroinflammatory-neurodegenerative gene regulation were between blast-associated trauma (BOP, BOP+CET) and CET. Following BOP, there were few DEGs detected amongst all 8 brain regions, most were related to cytokines/chemokines and chemokine receptors, where PPI analysis revealed Il1b as a potential central hub gene. In contrast, CET led to a more excessive and diverse pro-neuroinflammatory reaction in which Il6 was identified as the central hub gene. Analysis of the of the BOP+CET dataset, revealed a more global heightened response (Cxcr2, Il1b, and Il6) as well as the expression of additional functional regulatory networks/hub genes (Ccl2, Ccl3, and Ccl4) which are known to play a critical role in the rapid recruitment and activation of immune cells via chemokine/cytokine signaling. These findings provide a foundation for discerning pathophysiological consequences of acute extremity injury and systemic inflammation following various forms of trauma in the brain.

Effects of a Subanesthetic Ketamine Infusion on Inflammatory and Behavioral Outcomes after Closed Head Injury in Rats

Traumatic brain injury (TBI) affects millions of people annually, and most cases are classified as mild TBI (mTBI). Ketamine is a potent trauma analgesic and anesthetic with anti-inflammatory properties. However, ketamine's effects on post-mTBI outcomes are not well characterized. For the current study, we used the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA), which replicates the biomechanics of a closed-head impact with resulting free head movement. Adult male Sprague-Dawley rats sustained a single-session, repeated-impacts CHIMERA injury. An hour after the injury, rats received an intravenous ketamine infusion (0, 10, or 20 mg/kg, 2 h period), during which locomotor activity was monitored. Catheter blood samples were collected at 1, 3, 5, and 24 h after the CHIMERA injury for plasma cytokine assays. Behavioral assays were conducted on post-injury days (PID) 1 to 4 and included rotarod, locomotor activity, acoustic startle reflex (ASR), and pre-pulse inhibition (PPI). Brain tissue samples were collected at PID 4 and processed for GFAP (astrocytes), Iba-1 (microglia), and silver staining (axonal injury). Ketamine dose-dependently altered locomotor activity during the infusion and reduced KC/GRO, TNF-α, and IL-1β levels after the infusion. CHIMERA produced a delayed deficit in rotarod performance (PID 3) and significant axonal damage in the optic tract (PID 4), without significant changes in other behavioral or histological measures. Notably, subanesthetic doses of intravenous ketamine infusion after mTBI did not produce adverse effects on behavioral outcomes in PID 1-4 or neuroinflammation on PID 4. A further study is warranted to thoroughly investigate beneficial effects of IV ketamine on mTBI given multi-modal properties of ketamine in traumatic injury and stress.

Narrative Review: Low-Dose Ketamine for Pain Management

Pain is the leading cause of medical consultations and occurs in 50-70% of emergency department visits. To date, several drugs have been used to manage pain. The clinical use of ketamine began in the 1960s and it immediately emerged as a manageable and safe drug for sedation and anesthesia. The analgesic properties of this drug were first reported shortly after its use; however, its psychomimetic effects have limited its use in emergency departments. Owing to the misuse and abuse of opioids in some countries worldwide, ketamine has become a versatile tool for sedation and analgesia. In this narrative review, ketamine's role as an analgesic is discussed, with both known and new applications in various contexts (acute, chronic, and neuropathic pain), along with its strengths and weaknesses, especially in terms of psychomimetic, cardiovascular, and hepatic effects. Moreover, new scientific evidence has been reviewed on the use of additional drugs with ketamine, such as magnesium infusion for improving analgesia and clonidine for treating psychomimetic symptoms. Finally, this narrative review was refined by the experience of the Pain Group of the Italian Society of Emergency Medicine (SIMEU) in treating acute and chronic pain with acute manifestations in Italian Emergency Departments.

Acute Effects of Ketamine on Intracranial Pressure in Children With Severe Traumatic Brain Injury

OBJECTIVES

The acute cerebral physiologic effects of ketamine in children have been incompletely described. We assessed the acute effects of ketamine on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in children with severe traumatic brain injury (TBI).

DESIGN

In this retrospective observational study, patients received bolus doses of ketamine for sedation or as a treatment for ICP crisis (ICP > 20 mm Hg for > 5 min). Administration times were synchronized with ICP and CPP recordings at 1-minute intervals logged in an automated database within the electronic health record. ICP and CPP were each averaged in epochs following drug administration and compared with baseline values. Age-based CPP thresholds were subtracted from CPP recordings and compared with baseline values. Trends in ICP and CPP over time were assessed using generalized least squares regression.

SETTING

A 30-bed tertiary care children's hospital PICU.

PATIENTS

Children with severe TBI who underwent ICP monitoring.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We analyzed data from 33 patients, ages 1 month to 16 years, 22 of whom received bolus doses of ketamine, with 127 doses analyzed. Demographics, patient, and injury characteristics were similar between patients who did versus did not receive ketamine boluses. In analysis of the subset of ketamine doses used only for sedation, there was no significant difference in ICP or CPP from baseline. Eighteen ketamine doses were given during ICP crises in 11 patients. ICP decreased following these doses and threshold-subtracted CPP rose.

CONCLUSIONS

In this retrospective, exploratory study, ICP did not increase following ketamine administration. In the setting of a guidelines-based protocol, ketamine was associated with a reduction in ICP during ICP crises. If these findings are reproduced in a larger study, ketamine may warrant consideration as a treatment for intracranial hypertension in children with severe TBI.

Prospective observational study on the use of continuous intravenous ketamine and propofol infusion for prolonged sedation in critical care

INTRODUCTION

Analgesia and sedation are a priority in paediatric intensive care. The combination of ketamine and propofol is a possible option in patients requiring prolonged or difficult sedation and to reduce the use of benzodiazepines and opiates. The aim of this study was to assess the efficacy and safety of combination ketamine and propofol in continuous infusion for prolonged analgesia/sedation in the paediatric intensive care setting.

PATIENTS AND METHODS

Prospective, observational single-group cohort study in patients aged 1 month to 16 years admitted to the paediatric intensive care unit in 2016-2018 that received ketamine and propofol in continuous infusion for analgesia and sedation. We collected data on demographic and clinical characteristics, analgesia and sedation scores (MAPS, COMFORT-B and SOPHIA), haemodynamic parameters and adverse events.

RESULTS

The study included 32 patients. The maximum dose of ketamine was 1.5 mg/kg/h (interquartile range [IQR], 1-2 mg/kg/h) and the infusion duration was 5 days (IQR, 3-5 days). The maximum dose of propofol was 3.2 mg/kg/h (IQR, 2.5-3.6 mg/kg/h) and the infusion duration, 5 days (IQR, 3-5 days). Thirty (93.7%) patients had previously received midazolam and 29 (90.6%) fentanyl. Analgesia scores did not change after initiation of the ketamine and propofol infusion. There was a statistically significant increase in the COMFORT-B score, but the score remained in the adequate sedation range (12-17). There were small but statistically significant decreases in the mean arterial pressure (from 64 mmHg to 60 mmHg; P = .006) and the diastolic blood pressure (from 50.5 to 48 mmHg; P = .023) 1 h after the initiation of the ketamine and propofol infusion, but this difference was not observed 12 h later and did not require administration of vasoactive drugs. No other major adverse events were detected during the infusion.

CONCLUSIONS

The combination of ketamine and propofol in continuous infusion is a safe treatment in critically ill children that makes it possible to achieve an appropriate level of analgesia and sedation without relevant haemodynamic repercussions.

Neurosurgical Anesthesia: Optimizing Outcomes with Agent Selection

Anesthesia in neurosurgery embodies a vital element in the development of neurosurgical intervention. This undisputed interest has offered surgeons and anesthesiologists an array of anesthetic selections to utilize, though with this allowance comes the equally essential requirement of implementing a maximally appropriate agent. To date, there remains a lack of consensus and official guidance on optimizing anesthetic choice based on operating priorities including hemodynamic parameters (e.g., CPP, ICP, MAP) in addition to the route of procedure and pathology. In this review, the authors detail the development of neuroanesthesia, summarize the advantages and drawbacks of various anesthetic classes and agents, while lastly cohesively organizing the current literature of randomized trials on neuroanesthesia across various procedures.

The Prehospital Emergency Anaesthetic in 2022

Prehospital emergency anesthesia (PHEA) is a commonly performed prehospital procedure with inherent risks. The processes and drug regimens behind PHEA are continually updated by prehospital teams across the country as part of their governance structure. Essex & Herts Air Ambulance has recently updated this practice by reviewing the entire process of performing PHEA. Through experiential learning in a high-volume service, audit, and a contemporary literature review, a new standard operating procedure has been developed to combat common problems, such as hypotension, associated with the more traditional methods of performing PHEA. The aim of this article was to summarize the literature behind this new standard operating procedure, systematically breaking down the core components of performing a PHEA and the rationale behind them. The key components identified in the review are indications for PHEA, airway assessment, peri-intubation oxygenation, preparation for PHEA, drug dosing, special circumstances, and failed intubation. One significant change is the drug dosage regimen; 1 μg/kg fentanyl, 2 mg/kg ketamine, and 2 mg/kg rocuronium is recommended as the main drug dosing regimen for both medical and trauma patients. Other changes include preoxygenation with a nasal cannula in addition to the nonrebreather mask, optimizing patients in the preparation phase by considering inopressors or fluid bolus and ensuring a "sterile cockpit" to control the surrounding environment to ensure the first intubation attempt is the best attempt.

Co-administration of Ketamine in Pediatric Patients with Neurologic Conditions at Risk for Intracranial Hypertension

BACKGROUND

Ketamine has traditionally been avoided as an induction agent for tracheal intubation in patients with neurologic conditions at risk for intracranial hypertension due to conflicting data in the literature. The objective of this study was to evaluate and compare the effects of ketamine versus other medications as the primary induction agent on peri-intubation neurologic, hemodynamic and respiratory associated events in pediatric patients with neurologic conditions at risk for intracranial hypertension.

METHODS

This retrospective observational study enrolled patients < 18 years of age at risk for intracranial hypertension who were admitted to a quaternary children's hospital between 2015 and 2020. Associated events included neurologic, hemodynamic and respiratory outcomes comparing primary induction agents of ketamine versus non-ketamine for tracheal intubation.

RESULTS

Of 143 children, 70 received ketamine as the primary induction agent prior to tracheal intubation. Subsequently after tracheal intubation, all the patients received adjunct analgesic and sedative medications (fentanyl, midazolam, and/or propofol) at doses that were inadequate to induce general anesthesia but would keep them comfortable for further diagnostic workup. There were no significant differences between associated neurologic events in the ketamine versus non-ketamine groups (p = 0.42). This included obtaining an emergent computed tomography scan (p = 0.28), an emergent trip to the operating room within 5 h of tracheal intubation (p = 0.6), and the need for hypertonic saline administration within 15 min of induction drug administration for tracheal intubation (p = 0.51). There were two patients who had clinical and imaging evidence of herniation, which was not more adversely affected by ketamine compared with other medications (p = 0.49). Of the 143 patients, 23 had pre-intubation and post-intubation intracranial pressure values recorded; 11 received ketamine, and 3 of these patients had intracranial hypertension that resolved or improved, whereas the remaining 8 children had intracranial pressure within the normal range that was not exacerbated by ketamine. There were no significant differences in overall associated hemodynamic or respiratory events during tracheal intubation and no 24-h mortality in either group.

CONCLUSIONS

The administration of ketamine as the primary induction agent prior to tracheal intubation in combination with other agents after tracheal intubation in children at risk for intracranial hypertension was not associated with an increased risk of peri-intubation associated neurologic, hemodynamic or respiratory events compared with those who received other induction agents.

Pediatric Neuroanesthesia — a Review of the Recent Literature

Purpose of Review

Pediatric neuroanesthesia is a growing and still challenging subspecialty. The purpose of this review is to summarize the available knowledge and highlight the most recent findings of the literature on non-traumatic pediatric neuroanesthesia care.

Recent Findings

Several human studies have confirmed the negative effects of early life anesthetic exposure. According to non-human studies, volatile anesthetics and opioids contribute to tumor progression. Tranexamic acid effectively reduces perioperative blood loss; it is used in several different doses without standard guidelines on optimal dosing. The widespread use of neuromonitoring has necessitated the development of anesthetic methods that do not affect neuromuscular transmission.

Summary

Pediatric anesthetic neurotoxicity, management of intraoperative bleeding, and the effect of anesthesia on tumor growth are among the most debated and researched topics in pediatric neuroanesthesia. The lack of evidence and clinical guidelines underlines the need for further large prospective studies in this subspecialty.

Ketamine and Its Emergence in the Field of Neurology

The quest for a safe and effective anesthetic medication in the mid-20th century led to the discovery of CI-581, which was later named ketamine. Ketamine was labeled a “dissociative anesthetic” due to the state of sensory deprivation that it induces in the subjects receiving it. Although it enjoyed widespread use at the beginning of the Vietnam war, its use rapidly waned due to its psychedelic effect and it became more popular as a recreational drug, and in the field of veterinary medicine. However, as we gained more knowledge about its multiple sites of action, it has reemerged as a useful anesthetic/analgesic agent. In the last decade, the field of neurology has witnessed the growing use of ketamine for the treatment of several neurological conditions including migraine, status epilepticus, stroke, and traumatic brain injury (TBI). Ketamine acts primarily as a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. The binding of ketamine to NMDA receptors leads to decreased frequency and duration of Ca⁺² channel opening and thus inhibits glutaminergic transmission. This mechanism has proven to be neuroprotective in several neurological conditions. Ketamine does not increase intracranial pressure (ICP), and it maintains cerebral perfusion pressure (CPP) by increasing cerebral blood flow. Ketamine has also been shown to inhibit massive slow waves of neurological depolarizations called cortical spreading depolarizations (CSD), usually seen during acute neurological injury and are responsible for further neurological deterioration. Unlike other anesthetic agents, ketamine does not cause cardiac or respiratory suppression. All these favorable mechanisms and cerebral/hemodynamic actions have led to increased interest among clinicians and researchers regarding the novel uses of ketamine. This review will focus on the use of ketamine for various neurological indications.

Clinical Uses of Ketamine in Children: A Narrative Review

Ketamine is a phencyclidine derivative that acts as a noncompetitive N-methyl-D-aspartate as well as a glutamate receptor antagonist. It also has other minor mechanisms that contribute to its extensive drug profile. Ketamine is a bronchodilator and maintains normal airway reflexes and, thus, permits spontaneous respiration. This, coupled with the fact that it produces potent analgesia, makes it highly suitable for children.

Despite its many merits, the drug’s side effects, along with its cultural image of being a drug of abuse, a drug used in veterinary medicine, or a “date-rape drug” have sullied its reputation within the armamentarium of medicine. Even though it is widely used in developing countries, its use in Western nations has diminished. We have strived to explore the various clinical uses of ketamine in children through this article. In addition, the article also highlights how some of the fears associated with using the drug are unfounded and provides ways by which the drug’s side effects can be prevented and managed.

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.

Enhanced Recovery After Surgery (ERAS) for Cranial Tumor Resection: A Review

Enhanced Recovery After Surgery (ERAS) protocols describe a standardized method of preoperative, perioperative, and postoperative care to enhance outcomes and minimize complication risks surrounding elective surgical intervention. A growing body of evidence is being generated as we learn to apply principles of ERAS standardization to neurosurgical patients. First applied in spinal surgery, ERAS protocols have been extended to cranial neuro-oncological procedures. This review synthesizes recent findings to generate evidence-based guidelines to manage neurosurgical oncology patients with standardized systems and assess ability of these systems to coordinate multidisciplinary, patient-centric care efforts. Furthermore, we highlight the potential utility of multimedia, app-based communication platforms to facilitate patient education, autonomy, and team communication within each of the three settings.

Efficacy and safety of ketamine in mechanically ventilated intensive care unit patients: a scoping review

Objectives: Mechanically ventilated patients account for about one-third of all admissions to the intensive care unit (ICU). Ketamine has been conditionally recommended to aid with analgesia in such patients, with low quality of evidence available to support this recommendation. We aimed to perform a narrative scoping review of the current knowledge of the use of ketamine, with a specific focus on mechanically ventilated ICU patients. Methods: We searched MEDLINE and EMBASE for relevant articles. Bibliographies of retrieved articles were examined for references of potential relevance. We included studies that described the use of ketamine for postoperative and emergency department management of pain and in the critically unwell, mechanically ventilated population. Results: There are few randomised controlled trials evaluating ketamine's utility in the ICU. The evidence is predominantly retrospective and observational in nature and the results are heterogeneous. Available evidence is summarised in a descriptive manner, with a division made between high dose and low dose ketamine. Ketamine's pharmacology and use as an analgesic agent outside of the ICU is briefly discussed, followed by evidence for use in the ICU setting, with particular emphasis on analgesia, sedation and intubation. Finally, data on adverse effects including delirium, coma, haemodynamic adverse effects, raised intracranial pressure, hypersalivation and laryngospasm are presented. Conclusions: Ketamine is used in mechanically ventilated ICU patients with several potentially positive clinical effects. However, it has a significant side effect profile, which may limit its use in these patients. The role of low dose ketamine infusion in mechanically ventilated ICU patients is not well studied and requires investigation in high quality, prospective randomised trials.

Long-term increase in sensitivity to ketamine's behavioral effects in mice exposed to mild blast induced traumatic brain injury

Neurobehavioral deficits emerge in nearly 50% of patients following a mild traumatic brain injury (TBI) and may persist for months. Ketamine is used frequently as an anesthetic, analgesic and for management of persistent psychiatric complications. Although ketamine may produce beneficial effects in patients with a history of TBI, differential sensitivity to its impairing effects could make the therapeutic use of ketamine in TBI patients unsafe. This series of studies examined male C57BL/6 J mice exposed to a mild single blast overpressure (mbTBI) for indications of altered sensitivity to ketamine at varying times after injury. Dystaxia (altered gait), diminished sensorimotor gating (reduced prepulse inhibition) impaired working memory (step-down inhibitory avoidance) were examined in mbTBI and sham animals 15 min following intraperitoneal injections of saline or R,S-ketamine hydrochloride, from day 7-16 post injury and again from day 35-43 post injury. Behavioral performance in the forced swim test and sucrose preference test were evaluated on day 28 and day 74 post injury respectively, 24 h following drug administration. Dynamic gait stability was compromised in mbTBI mice on day 7 and 35 post injury and further exacerbated following ketamine administration. On day 14 and 42 post injury, prepulse inhibition was robustly decreased by mbTBI, which ketamine further reduced. Ketamine-associated memory impairment was apparent selectively in mbTBI animals 1 h, 24 h and day 28 post shock (tested on day 15/16/43 post injury). Ketamine selectively reduced immobility scores in the FST in mbTBI animals (day 28) and reversed mbTBI induced decreases in sucrose consumption (Day 74). These results demonstrate increased sensitivity to ketamine in mice when tested for extended periods after TBI. The results suggest that ketamine may be effective for treating neuropsychiatric complications that emerge after TBI but urge caution when used in clinical practice for enhanced sensitivity to its side effects in this patient population.

Ketamine for critically ill patients with severe acute brain injury: Protocol for a systematic review with meta-analysis and Trial Sequential Analysis of randomised clinical trials

INTRODUCTION

Intensive care for patients with severe acute brain injury aims both to treat the immediate consequences of the injury and to prevent and treat secondary brain injury to ensure a good functional outcome. Sedation may be used to facilitate mechanical ventilation, for treating agitation, and for controlling intracranial pressure. Ketamine is an N-methyl-D-aspartate receptor antagonist with sedative, analgesic, and potentially neuroprotective properties. We describe a protocol for a systematic review of randomised clinical trials assessing the beneficial and harmful effects of ketamine for patients with severe acute brain injury.

METHODS AND ANALYSIS

We will systematically search international databases for randomised clinical trials, including CENTRAL, MEDLINE, Embase, and trial registries. Two authors will independently review and select trials for inclusion, and extract data. We will compare ketamine by any regimen versus placebo, no intervention, or other sedatives or analgesics for patients with severe acute brain injury. The primary outcomes will be functional outcome at maximal follow up, quality of life, and serious adverse events. We will also assess secondary and exploratory outcomes. The extracted data will be analysed using Review Manager and Trials Sequential Analysis. Evidence certainty will be graded using GRADE.

ETHICS AND DISSEMINATION

The results of the systematic review will be disseminated through peer-reviewed publication. With the review, we hope to inform future randomised clinical trials and improve clinical practice.

PROSPERO NO

CRD42021210447.

Review and Updates on the Treatment of Refractory and Super Refractory Status Epilepticus

Refractory and super-refractory status epilepticus (RSE and SRSE) are life-threatening conditions requiring prompt initiation of appropriate treatment to avoid permanent neurological damage and reduce morbidity and mortality. RSE is defined as status epilepticus that persists despite administering at least two appropriately dosed parenteral medications, including a benzodiazepine. SRSE is status epilepticus that persists at least 24 h after adding at least one appropriately dosed continuous anesthetic (i.e., midazolam, propofol, pentobarbital, and ketamine). Other therapeutic interventions include immunotherapy, neuromodulation, ketogenic diet, or even surgical intervention in certain cases. Continuous electroencephalogram is an essential monitoring tool for diagnosis and treatment. In this review, we focus on the diagnosis and treatment of RSE and SRSE.

Key articles and guidelines for the emergency medicine clinical pharmacist: 2011-2018 update

PURPOSE

To summarize recently published research reports and practice guidelines on emergency medicine (EM)-related pharmacotherapy.

SUMMARY

Our author group was composed of 14 EM pharmacists, who used a systematic process to determine main sections and topics for the update as well as pertinent literature for inclusion. Main sections and topics were determined using a modified Delphi method, author and peer reviewer groups were formed, and articles were selected based on a comprehensive literature review and several criteria for each author-reviewer pair. These criteria included the document "Oxford Centre for Evidence-based Medicine - Levels of Evidence (March 2009)" but also clinical implications, interest to reader, and belief that a publication was a "key article" for the practicing EM pharmacist. A total of 105 articles published from January 2011 through July 2018 were objectively selected for inclusion in this review. This was not intended as a complete representation of all available pertinent literature. The reviewed publications address the management of a wide variety of disease states and topic areas that are commonly found in the emergency department: analgesia and sedation, anticoagulation, cardiovascular emergencies, emergency preparedness, endocrine emergencies, infectious diseases, neurology, pharmacy services and patient safety, respiratory care, shock, substance abuse, toxicology, and trauma.

CONCLUSION

There are many important recent additions to the EM-related pharmacotherapy literature. As is evident with the surge of new studies, guidelines, and reviews in recent years, it is vital for the EM pharmacist to continue to stay current with advancing practice changes.

Rapid sequence induction: where did the consensus go?

Background

Rapid Sequence Induction (RSI) was introduced to minimise the risk of aspiration of gastric contents during emergency tracheal intubation. It consisted of induction with the use of thiopentone and suxamethonium with the application of cricoid pressure.

This narrative review describes how traditional RSI has been modified in the UK and elsewhere, aiming to deliver safe and effective emergency anaesthesia outside the operating room environment. Most of the key aspects of traditional RSI – training, technique, drugs and equipment have been challenged and often significantly changed since the procedure was first described. Alterations have been made to improve the safety and quality of the intervention while retaining the principles of rapidly securing a definitive airway and avoiding gastric aspiration. RSI is no longer achieved by an anaesthetist alone and can be delivered safely in a variety of settings, including in the pre-hospital environment.

Conclusion

The conduct of RSI in current emergency practice is far removed from the original descriptions of the procedure. Despite this, the principles – rapid delivery of a definitive airway and avoiding aspiration, are still highly relevant and the indications for RSI remain relatively unchanged.

Ketamine for Pain Management: A Review of Literature and Clinical Application

Ketamine is a dissociative anesthetic used increasingly as analgesia for different manifestations of pain, including acute, chronic, cancer and perioperative pain as well as pain in the critically ill patient population. Its distinctive pharmacologic properties may provide benefits to individuals suffering from pain, including increased pain control and reduction in opioid consumption and tolerance. Despite wide variability in proposed dosing and method of administration when used for analgesia, it is important all clinicians be familiar with the pharmacodynamics of ketamine in order to appropriately anticipate its therapeutic and adverse effects.

Comeback of ketamine: resurfacing facts and dispelling myths

Initially known as CI-581, ketamine was first synthesized in 1962 as a replacement from phencyclidine. It has since been used as an anesthetic and analgesic. In addition, it has bronchodilating, sedative, and amnestic properties, preserving airway reflexes and sympathetic nervous system tone. Since the discovery of ketamine, it has been a major topic of discussion due to controversies regarding its usage in particular sets of patients. In the past 50 years, despite its potential benefits, it is not commonly used because of concerns of "emergence phenomenon," its use as a substance of abuse, and its systemic side effects. Since 2012, three World Health Organization reviews on ketamine have addressed its international control. Researchers have been studying this wonder drug for a decade worldwide. Many myths of ketamine regarding emergence phenomenon and its use in traumatic brain injury and open eye injury have been disproved in recent times. It is becoming popular in pre-hospital settings, critical care, emergency medicine, low-dose acute pain services, and adjuvant in regional anesthesia techniques. This review highlights the current consensus on the various applications of ketamine in the literature.

Intradiploic epidermoid cyst in a dog

CASE DESCRIPTION

A 10-year-old 7-kg (15.4-lb) neutered male Shih Tzu was referred for evaluation because of a sudden onset of dullness and intermittent vomiting of 1 to 2 weeks' duration. Two days prior to evaluation, clinical signs had worsened and 1 seizure was reported.

CLINICAL FINDINGS

A 3.5 × 2.5-cm soft, dome-shaped mass of the right occipital region of the head was noted on physical examination. Radiography and CT confirmed the presence of the mass and indicated its intra- and extracranial expansion. The MRI images showed compression of the cerebellum by the mass, with distinct margins of hypointensity on both T1- and T2-weighted images.

TREATMENT AND OUTCOME

Surgery was performed, and the mass was completely excised. The dog had mild ataxia, hypermetria, and head tremors after surgery. Histologic examination of the mass yielded a diagnosis of intradiploic epidermoid cyst. On examination 3 weeks after surgery, the previous neurologic signs had resolved. On examination 25 months after surgery, the dog remained free of clinical signs.

CLINICAL RELEVANCE

The present report described the clinical signs, diagnostic imaging results, and successful surgical removal of an intradiploic epidermoid cyst in a dog. Long-term prognosis may be good with complete removal of intradiploic epidermoid cysts in dogs.

An Analysis of Prolonged, Continuous Ketamine Infusions

INTRODUCTION

Opioids carry high risk of dependence, and patients can rapidly build tolerance after repetitive dosing. Low-dose ketamine is an analgesic agent alternative that provides more hemodynamic stability. We sought to describe the effects of prolonged ketamine use in non-burn patients.

MATERIALS AND METHODS

We queried the electronic health system at the Brooke Army Medical Center for patient encounters with ketamine infusions lasting >72 hours. We abstracted data describing demographics, vital signs, ketamine infusion dose and duration, and discharge diagnoses potentially relevant to ketamine side effects.

RESULTS

We identified 194 subjects who met the study inclusion criteria. The median age was 39 years, most were male (67.0%), and most were primarily admitted for a non-trauma reason (59.2%). The mean ketamine drip strength was 43.9 mg/h (95% CI, 36.7-51.1; range 0.1-341.6) and the mean drip length was 130.8 hours (95% CI, 120.3-141.2; range 71-493). Most subjects underwent mechanical ventilation (56.1%) at some point during the infusion and most survived to hospital discharge (83.5%). On a per-day basis, the average heart rate was 93 beats per minute, systolic blood pressure was 128 mmHg, diastolic blood pressure was 71 mmHg, oxygen saturation was 96%, and respiratory rate was 22 respirations per minute.

CONCLUSIONS

We demonstrate that continuous ketamine infusions provide a useful adjunct for analgesia and/or sedation. Further development of this adjunct modality may serve as an alternative agent to opioids.

Anesthetic Management of Patients Undergoing Open Suboccipital Surgery

The posterior cranial fossa with its complex anatomy houses key pathways regulating consciousness, autonomic functions, motor and sensory pathways, and cerebellar centers regulating balance and gait. The most common posterior fossa pathologies for which neurosurgical intervention may be necessary include cerebellopontine angle tumors, aneurysms, and metastatic lesions. The posterior cranial fossa can be accessed from variations of the supine, lateral, park-bench, prone, and sitting positions. Notable complications from positioning include venous air embolism, paradoxic air embolism, tension pneumocephalus, nerve injuries, quadriplegia, and macroglossia. An interdisciplinary approach with careful planning, discussion, and clinical management contributes to improved outcomes and reduced complications.

Ketamine in acute phase of severe traumatic brain injury "an old drug for new uses?"

Maintaining an adequate level of sedation and analgesia plays a key role in the management of traumatic brain injury (TBI). To date, it is unclear which drug or combination of drugs is most effective in achieving these goals. Ketamine is an agent with attractive pharmacological and pharmacokinetics characteristics. Current evidence shows that ketamine does not increase and may instead decrease intracranial pressure, and its safety profile makes it a reliable tool in the prehospital environment. In this point of view, we discuss different aspects of the use of ketamine in the acute phase of TBI, with its potential benefits and pitfalls.

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.

Super K for Super-R(efractory) Status Epilepticus: Bringing Down Seizures While Keeping Up Blood Pressure With Ketamine

Ketamine to treat super-refractory status epilepticus

Alkhachroum A, Der-Nigoghossian CA, Mathews E, Massad N, Letchinger R, Doyle K, Chiu W-T, Kromm J, Rubinos C, Velazquez A, Roh D, Agarwal S, Park S, Connolly S, Claassen J. Neurology. 2020;95(16):e2286-e2294. doi: 10.1212/WNL.0000000000010611.

Objective:

To test ketamine infusion efficacy in the treatment of superrefractory 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% CI: 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.

Principles of Pharmacotherapy of Seizures and Status Epilepticus

Status epilepticus is a neurological emergency with an outcome that is highly associated with the initial pharmacotherapy management that must be administered in a timely fashion. Beyond first-line therapy of status epilepticus, treatment is not guided by robust evidence. Optimal pharmacotherapy selection for individual patients is essential in the management of seizures and status epilepticus with careful evaluation of pharmacokinetic and pharmacodynamic factors. With the addition of newer antiseizure agents to the market, understanding their role in the management of status epilepticus is critical. Etiology-guided therapy should be considered in certain patients with drug-induced seizures, alcohol withdrawal, or autoimmune encephalitis. Some patient populations warrant special consideration, such as pediatric, pregnant, elderly, and the critically ill. Seizure prophylaxis is indicated in select patients with acute neurological injury and should be limited to the acute postinjury period.

Role of anaesthesia in neurosurgical enhanced recovery programmes

The application of Enhanced Recovery After Surgery (ERAS) in neurosurgical practice is a relatively new concept. A limited number of studies involving ERAS protocols within neurosurgery, specifically for elective craniotomy, have been published, contrary to the ERAS spine surgery pathways that are now promoted by numerous national and international dedicated surgical societies and hospitals. In this review, we want to present the patient surgical journey from an anaesthesia perspective through the key components that can be included in the ERAS pathways for neurosurgical procedures, both craniotomies and major spine surgery.

Sedation for Rapid Sequence Induction and Intubation of Neurologically Injured Patients

There are subtle physiologic and pharmacologic principles that should be understood for patients with neurologic injuries. These principles are especially true for managing patients with traumatic brain injuries. Prevention of hypotension and hypoxemia are major goals in the management of these patients. This article discusses the physiology, pitfalls, and pharmacology necessary to skillfully care for this subset of patients with trauma. The principles endorsed in this article are applicable both for patients with traumatic brain injury and those with spinal cord injuries.