The Use of Ketamine for Acute Treatment of Pain: A Randomized, Double-Blind, Placebo-Controlled Trial

Randomised controlled trial of analgesia for the management of acute severe pain from traumatic injury: study protocol for the paramedic analgesia comparing ketamine and morphine in trauma (PACKMaN)

BACKGROUND

Prehospital analgesia is often required after traumatic injury, currently morphine is the strongest parenteral analgesia routinely available for use by paramedics in the United Kingdom (UK) when treating patients with severe pain. This protocol describes a multi-centre, randomised, double blinded trial comparing the clinical and cost-effectiveness of ketamine and morphine for severe pain following acute traumatic injury.

METHODS

A two arm pragmatic, phase III trial working with two large NHS ambulance services, with an internal pilot. Participants will be randomised in equal numbers to either (1) morphine or (2) ketamine by IV/IO injection. We aim to recruit 446 participants over the age of 16 years old, with a self-reported pain score of 7 or above out of 10. Randomised participants will receive a maximum of 20 mg of morphine, or a maximum of 30 mg of ketamine, to manage their pain. The primary outcome will be the sum of pain intensity difference. Secondary outcomes measure the effectiveness of pain relief and overall patient experience from randomisation to arrival at hospital as well as monitoring the adverse events, resource use and cost-effectiveness outcomes.

DISCUSSION

The PACKMAN study is the first UK clinical trial addressing the clinical and cost-effectiveness of ketamine and morphine in treating acute severe pain from traumatic injury treated by NHS paramedics. The findings will inform future clinical practice and provide insights into the effectiveness of ketamine as a prehospital analgesia.

TRIAL REGISTRATION

ISRCTN, ISRCTN14124474. Registered 22 October 2020, https://www.isrctn.com/ISRCTN14124474.

Subanaesthetic single-dose ketamine as an adjunct to opioid analgesics for acute pain management in the emergency department: a systematic review and meta-analysis

OBJECTIVE

To evaluate the effectiveness of a subanaesthetic single-dose ketamine (SDK) as an adjunct to opioids for acute pain in emergency department (ED) settings.

DESIGN

Systematic review and meta-analysis.

METHODS

A systematic search was performed in MEDLINE, Embase, Scopus and Web of Science through March 2022. Randomised controlled trials (RCTs) that investigated SDK as an adjunct to opioids in adult patients for any painful condition in ED settings were selected. Two reviewers screened studies, extracted data and assessed study quality. Data were pooled using random-effects models. The primary outcome was mean pain intensity score measured at baseline, >0-15 min, >15-30 min, >30-45 min, 60 min, 90 min and 120 min. Secondary outcomes included need for rescue analgesia, adverse events and patient satisfaction. Results were reported as mean differences (MDs) and risk ratios. Statistical heterogeneity was calculated using the I ² statistic.

RESULTS

Eight RCTs were included (n=903). Studies were judged to be at moderate to high risk of bias. Mean pain intensity scores were significantly lower 60 min after study drug administration favouring adjuvant SDK (MD -0.76; 95% CI -1.19 to -0.33), compared with opioids alone. There was no evidence of differences in mean pain intensity scores at any other time point. Patients who received adjuvant SDK were less likely to require rescue analgesia, no more likely to experience serious side effects and had higher satisfaction scores, compared with opioids alone.

CONCLUSIONS

Available evidence suggests adjuvant SDK can have an effect on lowering pain intensity scores. Although reduction of pain scores was not clinically significant, the combination of reduced pain intensity and reduced opioid requirements suggest the results could be clinically important and support the potential utility of SDK as an adjunct to opioids to treat acute pain in adult ED patients. However, current evidence is limited and higher quality RCTs are needed.

PROSPERO REGISTRATION NUMBER

CRD42021276708.

Incidence of Dissociation With Low-Dose Pre-hospital Ketamine in Geriatric Patients With Trauma-Related Pain

Introduction

Sub-dissociative ketamine has been used increasingly for the treatment of acute pain in a wide variety of settings. While there are studies evaluating its use in the geriatric population, no studies have described its safety in the pre-hospital geriatric trauma patient. The objective of this study was to define the incidence of dissociation with low-dose pre-hospital ketamine in geriatric trauma patients.

Methods

Using our county emergency medical services database, we identified all trauma patients greater or equal to 65 years of age who received pre-hospital ketamine for pain after the implementation of a low-dose ketamine protocol. We retrospectively reviewed pre-hospital and emergency department records for demographics, traumatic injuries, Glasgow Coma Score, emergency department length of stay and disposition, and hospital length of stay. This group was compared to a similar population of trauma patients, transported prior to the ketamine protocol. The comparison group was chosen by matching the ketamine group to more than double the number of non-ketamine patients. Records were obtained from two separate trauma centers. Our primary outcome was documentation of “ketamine-related dissociation” by either the pre-hospital, emergency department or trauma provider. Secondary outcomes included emergency department length of stay and intensive care unit admission.

Results

Seventy-nine patients received ketamine with records available for analysis. One hundred ninety-three non-ketamine patients were compared to this group. There were nosignificant differences between the two groups in regards to age, weight, gender, or mechanism of injury. The injury severity score was higher in the ketamine group. Nine patients (11%) had documented dissociation after ketamine, with six of these patients back to baseline mentation by arrival to the emergency department. The emergency department length of stay was shorter in the ketamine group. The rate of intensive care unit admission was the same between both groups.

Conclusions

Pre-hospital sub-dissociative ketamine in geriatric trauma patients is associated with brief episodes of dissociation in a small minority of patients.

Lidocaine and Ketamine Infusions as Adjunctive Pain Management Therapy: A Retrospective Analysis of Clinical Outcomes in Hospitalized Patients Admitted for Pain Related to Sickle Cell Disease

Objective

In this study, we aim to evaluate the efficacy of adjunctive lidocaine and ketamine infusions for opioid reduction in the treatment of sickle cell disease in patients with vaso-occlusive crisis (VOC).

Design

We retrospectively reviewed a cohort of 330 adult sickle-cell crisis hospital encounters with 68 patients admitted to our institution from July 2017 to August 2018.

Methods

Upon institutional IRB approval, we obtained initial data from billing records and performed chart reviews to obtain pain scores and confirm total opioid consumption. If provided by the acute pain consultation service, the patients received either a lidocaine or a ketamine infusion of 0.5–2 mg/min or 2–3 mcg/kg, respectively, for a maximum of 24–48 h. We compared the change in opioid consumption before and after infusion therapy to patients that did not receive ketamine or lidocaine.

Results

Compared to patients that did not receive infusion therapy, ketamine and lidocaine accounted for respective relative decreases of 28 and 23% in average daily morphine consumption (p = 0.02). Patients that received either infusion were 3 to 4 times more likely to decrease their opioid consumption independent of treatment length or baseline opioid doses (p < 0.01). Ketamine and lidocaine therapies were not associated with change in pain scores. When a patient had multiple admissions, opioid reduction was strongly correlated with initiation of infusions in the later visits.

Conclusion

Both ketamine and lidocaine infusion therapies are effective in reducing opioid consumption for patients with vaso-occlusive crisis. Lidocaine infusion is emerging as an agent for stabilizing opioid doses in VOC for patients with high daily MME.

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.

Ketamine for Acute Pain Management and Sedation

TOPIC

Ketamine is beneficial in clinical settings ranging from procedural sedation to the treatment of chronic pain. This article describes the clinical benefits of ketamine for treatment of acute pain and for sedation of patients undergoing mechanical ventilation.

CLINICAL RELEVANCE

Ketamine causes analgesic and amnestic effects by noncompetitive inhibition of the N-methyl-D-aspartate receptor and activation of the opioid μ and κ receptors. Unlike other sedatives, ketamine provides analgesia and amnesia without causing hypotension or respiratory depression. Several studies have elucidated the clinical benefits of ketamine. The use of ketamine has extended beyond critical care areas such as the operating room and intensive care units. Nurses must be familiar with optimal clinical scenarios, monitoring parameters, and contraindications of ketamine.

PURPOSE

To highlight the clinical utility and pharmacological properties of ketamine through a literature review. Current studies of ketamine in acute pain and sedation management are summarized.

CONTENT COVERED

This narrative review describes pharmacological properties, dosing strategies, adminis-tration considerations, and adverse effects of ketamine.

Predictive performance of parent-metabolite population pharmacokinetic models of (S)-ketamine in healthy volunteers

Purpose

The recent repurposing of ketamine as treatment for pain and depression has increased the need for accurate population pharmacokinetic (PK) models to inform the design of new clinical trials. Therefore, the objectives of this study were to externally validate available PK models on (S)-(nor)ketamine concentrations with in-house data and to improve the best performing model when necessary.

Methods

Based on predefined criteria, five models were selected from literature. Data of two previously performed clinical trials on (S)-ketamine administration in healthy volunteers were available for validation. The predictive performances of the selected models were compared through visual predictive checks (VPCs) and calculation of the (root) mean (square) prediction errors (ME and RMSE). The available data was used to adapt the best performing model through alterations to the model structure and re-estimation of inter-individual variability (IIV).

Results

The model developed by Fanta et al. (Eur J Clin Pharmacol 71:441–447, 2015) performed best at predicting the (S)-ketamine concentration over time, but failed to capture the (S)-norketamine C_max correctly. Other models with similar population demographics and study designs had estimated relatively small distribution volumes of (S)-ketamine and thus overpredicted concentrations after start of infusion, most likely due to the influence of circulatory dynamics and sampling methodology. Model predictions were improved through a reduction in complexity of the (S)-(nor)ketamine model and re-estimation of IIV.

Conclusion

The modified model resulted in accurate predictions of both (S)-ketamine and (S)-norketamine and thereby provides a solid foundation for future simulation studies of (S)-(nor)ketamine PK in healthy volunteers after (S)-ketamine infusion.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-021-03104-1.

Patient-Reported outcomes of pain care research in the adult emergency department: A scoping review

Despite more than 30 years of research, pain in the emergency department (ED) setting is frequently undertreated. EDs prioritise process measures that often have tenuous links to patient-reported outcomes. However, process measures, such as time to the administration of first analgesic medication, are neither direct objective measures of analgesia nor appropriate surrogate markers of pain relief. Since pain is a subjective symptom that lacks an objective measure, pain research in any clinical environment, including EDs, should rely upon patient-reported outcomes. This scoping review examined patient-reported outcomes (PROs) and patient-reported outcome measures (PROMs) of pain care in the adult emergency department at the micro, meso and macro-level over the last ten years. We reviewed pain care research conducted on adults in EDs over the last ten years and identified 57 articles using 14 patient-reported outcomes of pain care falling into five broad areas, most without validation or adaption to the ED setting. Despite efforts made to incorporate PROs and PROMs into acute pain care research in the ED over the last ten years, there is still no gold-standard PROM in widespread use. We recommend the adaptation of existing tools with rigorous validation in ED populations.

Ketamine for pain control of snake envenomation in Guinea: A case series

Snakebite envenomation is a global health crisis and is classified as a Category A neglected tropical disease by the World Health Organization (WHO). Snakebite envenomations account for a significant amount of morbidity and morbidity in tropical and subtropical regions. Recently, publications have illustrated the potential for snake envenomations causing post-traumatic stress disorder (PTSD) in a significant number of patients. Ketamine is on the WHO's list of essential medications and is used for a variety of pharmacologic applications including anesthesia and acute pain management. To date it has not been assessed for pain control in snakebite envenomations. Twelve patients who presented with severe pain secondary to Bitis, Causus, and Atractaspis envenomations were treated with low-dose intravenous ketamine. The patients included 7 males and 5 females with a median age of 37.5 (range 14-64) and a median presentation time of 5.75 h (range 5 min-96 h) after the initial bite occurred. Ten envenomations were presumed to have been caused by Bitis species resulting in extensive swelling and blistering of the affected extremities. One envenomation was presumedC. maculatus causing local swelling and pain. One envenomation was a presumed Atractaspis species causing significant local pain with minimal swelling. All patients expressed having significant pain but could not express the degree of their pain using an analogue pain scale. An initial median dose of 5 mg of ketamine (range 2.5-15 mg) was administered intravenously for pain control. Every patient expressed decreased pain and felt more comfortable within 1 min after administration of ketamine. Nine of the twelve patients only required a single dose. There were no adverse side effects. Ketamine appears to be an effective means of pain control for those suffering from painful envenomations. With minimal risk of significant side effects at acute pain management doses and the average cost per effective dose averaging between US$0.03-0.06, this may provide a cheap, safe, and effective solution for Sub-saharan Africa and other resource-limited settings. Controlled studies need to be done to critically assess our observations.

Ketamine Safety and Use in the Emergency Department for Pain and Agitation/Delirium: A Health System Experience

INTRODUCTION

Two protocols were developed to guide the use of subdissociative dose ketamine (SDDK) for analgesia and dissociative sedation ketamine for severe agitation/excited delirium in the emergency department (ED). We sought to evaluate the safety of these protocols implemented in 18 EDs within a large health system.

METHODS

We conducted a retrospective chart review to evaluate all adult patients who received intravenous (IV) SDDK for analgesia and intramuscular (IM) dissociative sedation ketamine for severe agitation/excited delirium in 12 hospital-based and six freestanding EDs over a one-year period from the protocol implementation. We developed a standardized data collection form and used it to record patient information regarding ketamine use, concomitant medication use, and any comorbidities that could have impacted the incidence of adverse events.

RESULTS

Approximately 570,000 ED visits occurred during the study period. SDDK was used in 210 ED encounters, while dissociative sedation ketamine for severe agitation/excited delirium was used in 37 ED encounters. SDDK was used in 83% (15/18) of sites while dissociative sedation ketamine was used in 50% (9/18) of sites. Endotracheal intubation, non-rebreather mask, and nasal cannula ≥ four liters per minute were identified in one, five, and three patients, respectively. Neuropsychiatric adverse events were identified in 4% (9/210) of patients who received SDDK.

CONCLUSION

Patients experienced limited neuropsychiatric adverse events from SDDK. Additionally, dissociative sedation ketamine for severe agitation/excited delirium led to less endotracheal intubation than reported in the prehospital literature. The favorable safety profile of ketamine use in the ED may prompt further increases in usage.

KEA-1010, a ketamine ester analogue, retains analgesic and sedative potency but is devoid of Psychomimetic effects

Background

Ketamine, a widely used anaesthetic and analgesic agent, is known to improve the analgesic efficacy of opioids and to attenuate central sensitisation and opioid-induced hyperalgesia. Clinical use is, however, curtailed by unwanted psychomimetic effects thought to be mediated by N-methyl-D-aspartate (NMDA) receptor antagonism. KEA-1010, a ketamine ester-analogue designed for rapid offset of hypnosis through hydrolysis mediated break-down, has been shown to result in short duration sedation yet prolonged attenuation of nociceptive responses in animal models. Here we report on behavioural effects following KEA-1010 administration to rodents.

Methods

KEA-1010 was compared with racemic ketamine in its ability to produce loss of righting reflex following intravenous injection in rats. Analgesic activity was assessed in thermal tail flick latency (TFL) and paw incision models when injected acutely and when co-administered with fentanyl. Tail flick analgesic assessment was further undertaken in morphine tolerant rats. Behavioural aberration was assessed following intravenous injection in rats undergoing TFL assessment and in auditory pre-pulse inhibition models.

Results

KEA-1010 demonstrated an ED₅₀ similar to ketamine for loss of righting reflex following bolus intravenous injection (KEA-1010 11.4 mg/kg [95% CI 10.6 to 12.3]; ketamine (racemic) 9.6 mg/kg [95% CI 8.5–10.9]). Duration of hypnosis was four-fold shorter in KEA-1010 treated animals. KEA-1010 prolonged thermal tail flick responses comparably with ketamine when administered de novo, and augmented morphine-induced prolongation of tail flick when administered acutely. The analgesic effect of KEA-1010 on thermal tail flick was preserved in opioid tolerant rats. KEA-1010 resulted in increased paw-withdrawal thresholds in a rat paw incision model, similar in magnitude yet more persistent than that seen with fentanyl injection, and additive when co-administered with fentanyl. In contrast to ketamine, behavioural aberration following KEA-1010 injection was largely absent and no pre-pulse inhibition to acoustic startle was observed following KEA-1010 administration in rats.

Conclusions

KEA-1010 provides antinociceptive efficacy in acute thermal and mechanical pain models that augments standard opioid analgesia and is preserved in opioid tolerant rodents. The NMDA channel affinity and psychomimetic signature of the parent compound ketamine is largely absent for KEA-1010.

Comparative Effectiveness of Analgesics to Reduce Acute Pain in the Prehospital Setting

Objectives: The objectives of this study were to assess comparative effectiveness and harms of opioid and nonopioid analgesics for the treatment of moderate to severe acute pain in the prehospital setting. Methods: We searched MEDLINE^®, Embase^®, and Cochrane Central from the earliest date through May 9, 2019. Two investigators screened abstracts, reviewed full-text files, abstracted data, and assessed study level risk of bias. We performed meta-analyses when appropriate. Conclusions were made with consideration of established clinically important differences and we graded each conclusion's strength of evidence (SOE). Results: We included 52 randomized controlled trials and 13 observational studies. Due to the absence or insufficiency of prehospital evidence we based conclusions for initial analgesia on indirect evidence from the emergency department setting. As initial analgesics, there is no evidence of a clinically important difference in the change of pain scores with opioids vs. ketamine administered primarily intravenously (IV) (low SOE), IV acetaminophen (APAP) (low SOE), or nonsteroidal anti-inflammatory drugs (NSAIDs) administered primarily IV (moderate SOE). The combined use of an opioid and ketamine, administered primarily IV, may reduce pain more than an opioid alone at 15 and 30 minutes (low SOE). Opioids may cause fewer adverse events than ketamine (low SOE) when primarily administered intranasally. Opioids cause less dizziness than ketamine (low SOE) but may increase the risk of respiratory depression compared with ketamine (low SOE), primarily administered IV. Opioids cause more dizziness (moderate SOE) and may cause more adverse events than APAP (low SOE), both administered IV, but there is no evidence of a clinically important difference in hypotension (low SOE). Opioids may cause more adverse events and more drowsiness than NSAIDs (low SOE), both administered primarily IV. Conclusions: As initial analgesia, opioids are no different than ketamine, APAP, and NSAIDs in reducing acute pain in the prehospital setting. Opioids may cause fewer total side effects than ketamine, but more than APAP or NSAIDs. Combining an opioid and ketamine may reduce acute pain more than an opioid alone but comparative harms are uncertain. When initial morphine is inadequate, giving ketamine may provide greater and quicker acute pain relief than giving additional morphine, although comparative harms are uncertain. Due to indirectness, strength of evidence is generally low, and future research in the prehospital setting is needed.

Ketamine Use for Successful Resolution of Post-ERCP Acute Pancreatitis Abdominal Pain

We report a case in which a patient with intractable pain secondary to post-endoscopic retrograde cholangiopancreatography (ERCP) acute pancreatitis is successfully treated with a subanesthetic ketamine infusion. Shortly after ERCP, the patient reported severe stabbing epigastric pain. She exhibited voluntary guarding and tenderness without distension. Amylase and lipase levels were elevated. Pain persisted for hours despite hydromorphone PCA, hydromorphone boluses, fentanyl boluses, and postprocedure anxiolytics. Pain management was consulted and a ketamine infusion was trialed, leading to a dramatic reduction in pain. This case suggests that ketamine may be a promising option in treating intractable pain associated with ERCP acute pancreatitis.