Out-of-Hospital Ketamine: Indications for Use, Patient Outcomes, and Associated Mortality

Fixed dose ketamine for prehospital management of hyperactive delirium with severe agitation

INTRODUCTION

Patients exhibiting signs of hyperactive delirium with severe agitation (HDSA) may require sedating medications for stabilization and safe transport to the hospital. Determining the patient's weight and calculating the correct weight-based dose may be challenging in an emergency. A fixed dose ketamine protocol is an alternative to the traditional weight-based administration, which may also reduce dosing errors. The objective of this study was to evaluate the frequency and characteristics of adverse events following pre-hospital ketamine administration for HDSA.

METHODS

Emergency Medical Services (EMS) records from four agencies were searched for prehospital ketamine administration. Cases were included if a 250 mg dose of ketamine was administered on standing order to an adult patient for clinical signs consistent with HDSA. Protocols allowed for a second 250 mg dose of ketamine if the first dose was not effective. Both the 250 mg initial dose and the total prehospital dose were analyzed for weight based dosing and adverse events.

RESULTS

Review of 132 cases revealed 60 cases that met inclusion criteria. Patients' median weight was 80 kg (range: 50-176 kg). No patients were intubated by EMS, one only requiring suction, three required respiratory support via bag valve mask (BVM). Six (10%) patients were intubated in the emergency department (ED) including the three (5%) supported by EMS via BVM, three (5%) others who were sedated further in the ED prior to requiring intubation. All six patients who were intubated were discharged from the hospital with a Cerebral Performance Category (CPC) 1 score. The weight-based dosing equivalent for the 250 mg initial dose (OR: 2.62, CI: 0.67-10.22) and the total prehospital dose, inclusive of the 12 patients that were administered a second dose, (OR: 0.74, CI: 0.27, 2.03), were not associated with the need for intubation.

CONCLUSION

The 250 mg fixed dose of ketamine was not >5 mg/kg weight-based dose equivalent for all patients in this study. Although a second 250 mg dose of ketamine was permitted under standing orders, only 12 (20%) of the patients were administered a second dose, none experienced an adverse event. This indicates that the 250 mg initial dose was effective for 80% of the patients. Four patients with prehospital adverse events likely related to the administration of ketamine were found. One required suction, three (5%) requiring BVM respiratory support by EMS were subsequently intubated upon arrival in the ED. All 60 patients were discharged from the hospital alive. Further research is needed to determine an optimal single administration dose for ketamine in patients exhibiting signs of HDSA, if employing a standardized fixed dose medication protocol streamlines administration, and if the fixed dose medication reduces the occurrence of dosage errors.

Effectiveness of Intranasal Analgesia in the Emergency Department

In the Emergency Department (ED), pain is one of the symptoms that are most frequently reported, making it one of the most significant issues for the emergency physician, but it is frequently under-treated. Intravenous (IV), oral (PO), and intramuscular (IM) delivery are the standard methods for administering acute pain relief. Firstly, we compared the safety and efficacy of IN analgesia to other conventional routes of analgesia to assess if IN analgesia may be an alternative for the management of acute pain in ED. Secondly, we analyzed the incidence and severity of adverse events (AEs) and rescue analgesia required. We performed a narrative review-based keywords in Pubmed/Medline, Scopus, EMBASE, the Cochrane Library, and Controlled Trials Register, finding only twenty randomized Clinical trials eligible in the timeline 1992-2022. A total of 2098 patients were analyzed and compared to intravenous analgesia, showing no statistical difference in adverse effects. In addition, intranasal analgesia also has a rapid onset and quick absorption. Fentanyl and ketamine are two intranasal drugs that appear promising and may be taken simply and safely while providing effective pain relief. Intravenous is simple to administer, non-invasive, rapid onset, and quick absorption; it might be a viable choice in a variety of situations to reduce patient suffering or delays in pain management.

Association of Ketamine Dosing with Intubation and Other Adverse Events in Patients with Behavioral Emergencies

Objective: Varying rates of complications have been reported for prehospital sedation with ketamine, and the relationship to dosing has not been studied on a large scale. We evaluated the association between prehospital ketamine dosing and rates of intubations and other adverse events in patients with behavioral emergencies.Methods: Using the 2018/2019 ESO public-use research datasets, we included all non-traumatic, adult behavioral and drug-related EMS encounters with ketamine administration. Based on consensus guidelines, we stratified patients into "above" and "at/below" the maximum dosing for sedation (2 mg/kg IV/IO or 5 mg/kg IM) using the highest single dose of ketamine given. We created propensity scores for matched subjects using 1:1 propensity score matching. Using logistic regression, we compared rates of intubation and other airway interventions, antipsychotic coadministration, improvement reported by EMS, hypoxia, hypotension, and cardiac arrest between the two groups.Results: We included 2,383 patients: 478 in the above and 1,905 in the at/below dose group. Above dose ketamine was associated with a higher rate of intubation or supraglottic airway placement (6.4% v 3.3%, OR 2.0, 95% CI 1.00-3.90). Other airway interventions were similar (40.0% v 40.0%, OR 1, 95% CI 0.80-1.30). The above dose group also showed a higher rate of improvement noted by EMS clinicians (92.5% v 88.7%, OR 1.6, 95% CI 1.01-2.40). The rates of antipsychotic coadministration, hypoxia, hypotension, and cardiac arrest were similar between the cohorts.Conclusions: Patients given ketamine doses above consensus recommendations for sedation appeared more likely to receive prehospital intubation, but not more likely to experience other adverse events.

The clinical toxicology of ketamine

INTRODUCTION

Ketamine is a pharmaceutical drug possessing both analgesic and anaesthetic properties. As an anaesthetic, it induces anaesthesia by producing analgesia with a state of altered consciousness while maintaining airway tone, respiratory drive, and hemodynamic stability. At lower doses, it has psychoactive properties and has gained popularity as a recreational drug.

OBJECTIVES

To review the epidemiology, mechanisms of toxicity, pharmacokinetics, clinical features, diagnosis and management of ketamine toxicity.

METHODS

Both OVID MEDLINE (January 1950-April 2023) and Web of Science (1900-April 2023) databases were searched using the term "ketamine" in combination with the keywords "pharmacokinetics", "kinetics", "poisoning", "poison", "toxicity", "ingestion", "adverse effects", "overdose", and "intoxication". Furthermore, bibliographies of identified articles were screened for additional relevant studies. These searches produced 5,268 non-duplicate citations; 185 articles (case reports, case series, pharmacokinetic studies, animal studies pertinent to pharmacology, and reviews) were considered relevant. Those excluded were other animal investigations, therapeutic human clinical investigations, commentaries, editorials, cases with no clinical relevance and post-mortem investigations.

EPIDEMIOLOGY

Following its introduction into medical practice in the early 1970s, ketamine has become a popular recreational drug. Its use has become associated with the dance culture, electronic and dubstep dance events.

MECHANISM OF ACTION

Ketamine acts primarily as a non-competitive antagonist on the glutamate N-methyl-D-aspartate receptor, causing the loss of responsiveness that is associated with clinical ketamine dissociative anaesthesia.

PHARMACOKINETICS

Absorption of ketamine is rapid though the rate of uptake and bioavailability is determined by the route of exposure. Ketamine is metabolized extensively in the liver. Initially, both isomers are metabolized to their major active metabolite, norketamine, by CYP2B6, CYP3A4 and CYP2C9 isoforms. The hydroxylation of the cyclohexan-1-one ring of norketamine to the three positional isomers of hydroxynorketamine occurs by CYP2B6 and CYP2A6. The dehydronorketamine metabolite occurs either by direct dehydrogenation from norketamine via CYP2B6 metabolism or non-enzymatic dehydration of hydroxynorketamine. Norketamine, the dehydronorketamine isomers, and hydroxynorketamine have pharmacological activity. The elimination of ketamine is primarily by the kidneys, though unchanged ketamine accounts for only a small percentage in the urine. The half-life of ketamine in humans is between 1.5 and 5 h.

CLINICAL FEATURES

Acute adverse effects following recreational use are diverse and can include impaired consciousness, dizziness, irrational behaviour, hallucinations, abdominal pain and vomiting. Chronic use can result in impaired verbal information processing, cystitis and cholangiopathy.

DIAGNOSIS

The diagnosis of acute ketamine intoxication is typically made on the basis of the patient's history, clinical features, such as vomiting, sialorrhea, or laryngospasm, along with neuropsychiatric features. Chronic effects of ketamine toxicity can result in cholangiopathy and cystitis, which can be confirmed by endoscopic retrograde cholangiopancreatography and cystoscopy, respectively.

MANAGEMENT

Treatment of acute clinical toxicity is predominantly supportive with empiric management of specific adverse effects. Benzodiazepines are recommended as initial treatment to reduce agitation, excess neuromuscular activity and blood pressure. Management of cystitis is multidisciplinary and multi-tiered, following a stepwise approach of pharmacotherapy and surgery. Management of cholangiopathy may require pain management and, where necessary, biliary stenting to alleviate obstructions. Chronic effects of ketamine toxicity are typically reversible, with management focusing on abstinence.

CONCLUSIONS

Ketamine is a dissociative drug employed predominantly in emergency medicine; it has also become popular as a recreational drug. Its recreational use can result in acute neuropsychiatric effects, whereas chronic use can result in cystitis and cholangiopathy.

Nebulized Ketamine for Analgesia in the Prehospital Setting: A Case Series

We report the initial seven patients treated with nebulized ketamine for moderate to severe pain, via breath-actuated nebulizer, in an urban, ground-based emergency medical services (EMS) system. Ketamine for analgesia in the emergency setting has become widespread over the past decade. The addition of a non-parenteral, inexpensive, and well-tolerated ketamine delivery option is extremely desirable. We believe these initial data demonstrate promising pain reduction coupled with minimal side effects, indicating a potential role for nebulized ketamine in EMS.

Ambulance Transport Destinations In The US Differ By Patient Race And Ethnicity

Patients in the US belonging to racial or ethnic minority groups often receive medical care in different hospitals than White patients, which contributes to health care disparities. We explored whether ambulance transport destinations contribute to this phenomenon. Using a national emergency medical services research data set for calendar year 2020, we made within-ZIP code comparisons of the transport destinations for White patients and non-White patients transported by ambulance from emergency scenes. We used the dissimilarity index to measure transport destination discordances and decided a priori that a more than 5 percent difference in transport destinations (that is, dissimilarity index >0.05) would be practically meaningful. We found meaningful differences in the destination hospitals for White and non-White patients transported by ambulance from locations in the same ZIP code. The median ZIP code dissimilarity index was 0.08, 64 percent of ZIP codes had a dissimilarity index above 0.05, and 61 percent of patients were transported from ZIP codes with a dissimilarity index above 0.05. Forty-one percent of ZIP codes had a dissimilarity index above 0.10, and one-third of the patients were transported from those ZIP codes. These data indicate that ambulance transport destinations contribute to discordances in where White and non-White patients receive medical care.

Prehospital Use of Ketamine versus Benzodiazepines for Sedation among Pediatric Patients with Behavioral Emergencies

INTRODUCTION

Ketamine is an emerging alternative sedation agent for prehospital management of agitation, yet research is limited regarding its use for children. Our objective was to compare the effectiveness and safety of ketamine and benzodiazepines when used for emergent prehospital sedation of pediatric patients with behavioral emergencies.

METHODS

We performed a retrospective review of 9-1-1 EMS records from the 2019-2020 ESO Data Collaborative research datasets. We included patients ≤18 years of age who received ketamine or benzodiazepines for EMS primary and secondary impressions indicating behavioral conditions. We excluded patients with first Glasgow Coma Scale (GCS) scores ≤8, those receiving ketamine or benzodiazepines prior to EMS arrival, those receiving both ketamine and benzodiazepines, and interfacility transfers. Effectiveness outcomes included general clinician assessment of improvement, decrease in GCS, and administration of a subsequent sedative. Safety outcomes included mortality; advanced airway placement; ventilatory assistance without advanced airway placement; or marked sedation (GCS ≤8). Chi-square and t-tests were used to compare the ketamine and benzodiazepines groups.

RESULTS

Of 57,970 pediatric patients with behavioral complaints and GCS scores >8, 1,539 received ketamine (13.3%, n = 205) or a benzodiazepine (86.7%, n = 1,334). Most patients were ≥12 years old (89.2%, n = 1,372), predominantly Caucasian (48.3%, n = 744), and were equally distributed by sex (49.7% male, n = 765). First treatment with ketamine was associated with a greater likelihood of improvement (88.8% vs 70.5%, p < 0.001) and a greater average GCS reduction compared to treatment with benzodiazepines (-2.5 [SD:4.0] vs -0.3 [SD:1.7], p < 0.001). Fewer patients who received ketamine received subsequent medication compared to those who received benzodiazepines (12.2% vs 27.0%, p < 0.001). Marked sedation was more frequent with ketamine than benzodiazepines (28.8% vs 2.9%, p < 0.001). Provision of ventilatory support (1.5% vs 0.5%, p = 0.14) and advanced airway placement (1.0% vs 0.2%, p = 0.09) were similar between ketamine and benzodiazepine groups. No prehospital deaths were reported.

CONCLUSION

In this pediatric cohort, prehospital sedation with ketamine was associated with greater patient improvement, less subsequent sedative administration, and greater sedation compared to benzodiazepines. Though we identified low rates of adverse events in both groups, ketamine was associated with more instances of marked sedation, which bears further study.

Novel uses of ketamine in the emergency department

INTRODUCTION

: Ketamine is gaining renewed interest among healthcare providers due to its novel clinical applications in the emergency department (ED) setting.

AREAS COVERED

: This article provides a comprehensive discussion of ketamine's pharmacological properties, including safety profile and adverse effects, in addition to an overview of current evidence for ketamine (racemic formulation) in the management of ED patients with acute agitation, pain, and depression/suicide ideation.

EXPERT OPINION

: Ketamine is an effective adjunct to opioids, providing greater pain relief than morphine alone. As an analgesic agent, administration of ketamine (0.1-0.3 mg/kg IV) alone can provide analgesia similar to that of morphine in patients with acute visceral and musculoskeletal pain. Moreover, ketamine provides equal analgesic efficacy to morphine in a variety of chronic painful conditions including pain associated with cancer, vaso-occlusive pain crisis associated with sickle cell disease, and in patients with high opioid tolerance and/or opioid dependency. Available literature shows that ketamine (1-2mg/kg IV or 4-5 mg/kg IM) is a safe, rapid (<5 minutes) and effective tranquilization agent for ED patients with acute agitation. Finally, there is growing evidence that suggests ketamine may have a potential utility in the management of patients with self-harm ideation or acute depressive episodes. Intravenous infusion of ketamine (0.5 mg/kg over 40 mins) has been shown to produce an antidepressant effect and decrease in suicidal ideation within 4 hours with effects lasting up to one week.

Rapid tranquilization of the agitated patient in the emergency department: A systematic review and network meta-analysis

BACKGROUND

Safe and effective tranquilization of the acutely agitated patient is challenging, and head-to-head comparisons of medications are limited. We aimed to identify the most optimal agent(s) for rapid tranquilization of the severely agitated patient in the emergency department (ED).

METHODS

The protocol for systematic review was registered (PROSPERO; CRD42020212534). We searched MEDLINE, Embase, PsycINFO, and Cochrane Database/CENTRAL from inception to June 2, 2021. We limited studies to randomized controlled trials that enrolled adult ED patients with severe agitation and compared drugs for rapid tranquilization. Predetermined outcomes were: 1) Adequate sedation within 30 min (effectiveness), 2) Immediate, serious adverse event - cardiac arrest, ventricular tachydysrhythmia, endotracheal intubation, laryngospasm, hypoxemia, hypotension (safety), and 3) Time to adequate sedation (effect onset). We extracted data according to PRISMA-NMA and appraised trials using Cochrane RoB 2 tool. We performed Bayesian network meta-analysis (NMA) using a Markov Chain Monte Carlo method with random-effects model and vague prior distribution to calculate odds ratios with 95% credible intervals for dichotomous outcomes and frequentist NMA to calculate mean differences with 95% confidence intervals for continuous outcomes. We assessed confidence in results using CINeMA. We used surface under the cumulative ranking (SUCRA) curves to rank agent(s) for each outcome.

RESULTS

Eleven studies provided data for effectiveness (1142 patients) and safety (1147 patients). Data was insufficient for effect onset. The NMA found that ketamine (SUCRA = 93.0%) is most likely to have superior effectiveness; droperidol-midazolam (SUCRA = 78.8%) is most likely to be safest. There are concerns with study quality and imprecision. Quality of the point estimates varied for effectiveness but mostly rated "very low" for safety.

CONCLUSIONS

Available evidence suggests that ketamine and droperidol have intermediate effectiveness for rapid tranquilization of the severely agitated patient in the ED. There is insufficient evidence to definitively determine which agent(s) may be safest or fastest-acting. Further, direct-comparison study of ketamine and droperidol is recommended.