Low-dose ketamine for analgesia in the ED: a retrospective case series

Efficacy and Safety of Ketamine Versus Opiates in the Treatment of Patients with Renal Colic: A Systematic Review and Meta-analysis

INTRODUCTION

Renal colic is one of the most common urological emergencies, and is usually caused by ureteral colic spasms. Pain management in renal colic remains the central focus of emergency treatment. The purpose of this meta-analysis is to identify the efficacy and safety of ketamine versus opioids in the treatment of patients with renal colic.

METHODS

We searched PubMed, EMBASE, Cochrane Library, and Web of Science databases for published randomized controlled trials (RCTs) that referred to the use of ketamine and opioids for patients with renal colic. The methodology was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The mean difference (MD) or odds ratio (OR) with a 95% confidence interval (CI) was used to analyze the data. The results were pooled using a fixed-effects model or random-effects model. The primary outcome measure was patient-reported pain scores 5, 15, 30, and 60 min after drug administration. The secondary outcome measure was side effects.

RESULTS

The data analysis revealed that ketamine was similar to opioids in pain intensity at the time of 5 min post-dose (MD = - 0.40, 95% CI - 1.82 to 1.01, P = 0.57), 15 min post-dose (MD = - 0.15, 95% CI - 0.82 to 0.52, P = 0.67), 30 min post-dose (MD = 0.38, 95% CI - 0.25 to 1.01, P = 0.24). Also, the pain score of ketamine was better than that of opioids at 60 min after administration (MD = - 0.12, 95% CI - 0.22 to - 0.02, P = 0.02). As for safety, the ketamine group was linked to a significant decrease in the incidence of hypotensive (OR = 0.08, 95% CI 0.01-0.65, P = 0.02). The two groups did not statistically differ in the incidence of nausea, vomiting, and dizziness.

CONCLUSIONS

Compared with opioids, ketamine showed a longer duration of analgesia in renal colic, with satisfactory safety.

TRIAL REGISTRATION

The PROSPERO registration number is CRD42022355246.

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.

A Case Report of Subanesthetic Ketamine Bolus and Infusion for Opioid Refractory Cancer Pain

Opioids and traditional adjuvant medications are frequently prescribed for the management of moderate to severe cancer pain with good effect. However, there are many cases, in which patients experience severe opioid refractory cancer pain. Ketamine is being used more frequently in the hospice and palliative setting to manage opioid refractory pain, although high-quality evidence regarding its effectiveness is lacking. It seems certain patients respond favorably to ketamine, while others experience no effect. Studies have not yet identified factors associated with a favorable response to ketamine. We present a case describing the successful treatment of high-dose opioid refractory cancer pain with a subanesthetic ketamine infusion and propose the novel use of a preinfusion test bolus of ketamine to identify patients who are likely to respond favorably to an infusion.

Effects of ketamine analgesia on cardiorespiratory responses and survival to trauma and hemorrhage in rats

Ketamine is the recommended analgesic on the battlefield for soldiers with hemorrhage, despite a lack of supportive evidence from laboratory or clinical studies. Hence, this study determined the effects of ketamine analgesia on cardiorespiratory responses and survival to moderate (37% blood volume; n = 8/group) or severe hemorrhage (50% blood volume; n = 10/group) after trauma in rats. We used a conscious hemorrhage model with extremity trauma (fibular fracture + soft tissue injury) while measuring mean arterial pressure (MAP), heart rate (HR), and body temperature (T_b) by telemetry, and respiration rate (RR), minute volume (MV), and tidal volume (TV) via whole body plethysmography. Male rats received saline (S) or 5.0 mg/kg ketamine (K) (100 µL/100 g body wt) intra-arterially after trauma and hemorrhage. All rats survived 37% hemorrhage. For 50% hemorrhage, neither survival times [180 min (SD 78) vs. 209 min (SD 66)] nor percent survival (60% vs. 80%) differed between S- and K-treated rats. After 37% hemorrhage, K (compared with S) increased MAP and decreased T_b and MV. After 50% hemorrhage, K (compared with S) increased MAP but decreased HR and MV. K effects on cardiorespiratory function were time dependent, significant but modest, and transient at the analgesic dose given. K effects on T_b were also significant but modest and more prolonged. With the use of this rat model, our data support the use of K as an analgesic in injured, hypovolemic patients.NEW & NOTEWORTHY Ketamine administration at a dose shown to alleviate pain in nonhemorrhaged rats with extremity trauma had only modest and transient effects on multiple aspects of cardiorespiratory function after both moderate (37%) and severe (50%) traumatic hemorrhages. Such effects did not alter survival.

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.

Severe hyperammonemia from intense skeletal muscle activity: A rare case report and literature review

RATIONALE

Adult hyperammonemia is most often the result of hepatic dysfunction. Hyperammonemia in the setting of normal hepatic function is a much less common phenomenon and has usually been associated with medications and certain disease states. Here, we present an unusual case of severe hyperammonemia caused physiologically by intense muscle activity in a patient lacking any evidence of liver disease.

PATIENT CONCERNS

A 36-year-old woman was brought to the emergency department for a suicide attempt after being found covered in Lysol and Clorox germicidal bleach. She was noted to be in a state of violent psychosis with extreme agitation and had to be sedated and intubated for airway protection.

DIAGNOSIS AND INTERVENTIONS

Initial labs revealed hyperammonemia, lactic acidosis, and anion gap metabolic acidosis. Aminotransferases, bilirubin, and creatine kinase (CK) were normal. Renal function, prothrombin time, activated partial thromboplastin time, and international normalized ratio were also unremarkable and remained so at 24 hours. Ethyl alcohol, acetaminophen, salicylate, and valproic acid were all undetectable in blood. She received 2 doses of lactulose overnight, with a subsequent bowel movement. Next day, her mentation, serum ammonia level, and lactic acid level were back to normal, and she was extubated. Aminotransferases and CK levels were elevated but improved with supportive care. A detailed history and relevant biochemical investigations were unremarkable for any other etiology of hyperammonemia including the common inborn errors of metabolism (IEM). The combination of clinical findings of extreme skeletal muscle activity along with hyperammonemia and lactic acidosis, and subsequently rhabdomyolysis in the setting of unremarkable history and otherwise normal hepatic function strongly suggest the myokinetic origin of hyperammonemia in the patient.

OUTCOME

The patient recovered well with supportive care and was discharged on day 5.

LESSONS

This unique case illustrates the important role of skeletal muscle in the human metabolism of ammonia. In our discussion, we also elucidate the underlying pathophysiology, with the objective of improving clinician understanding of various differential diagnoses.

Intravenous subdissociative-dose ketamine versus morphine for acute geriatric pain in the Emergency Department: A randomized controlled trial

STUDY OBJECTIVE

We compare the analgesic efficacy and safety of subdissociative intravenous-dose ketamine (SDK) versus morphine in geriatric Emergency Department (ED) patients.

METHODS

This was a prospective, randomized, double-blind trial evaluating ED patients aged 65 and older experiencing moderate to severe acute abdominal, flank, musculoskeletal, or malignant pain. Patients were randomized to receive SDK at 0.3 mg/kg or morphine at 0.1 mg/kg by short intravenous infusion over 15 min. Evaluations occurred at 15, 30, 60, 90, and 120 min. Primary outcome was reduction in pain at 30 min. Secondary outcomes included overall rates of adverse effects and incidence of rescue analgesia.

RESULTS

Thirty patients per group were enrolled in the study. The primary change in mean pain scores was not significantly different in the ketamine and morphine groups: 9.0 versus 8.4 at baseline (mean difference 0.6; 95% CI -0.30 to 1.43) and 4.2 versus 4.4 at 30 min (mean difference -0.2; 95% CI -1.93 to1.46). Patients in the SDK group reported higher rates of psychoperceptual adverse effects at 15, 30, and 60 min post drug administration. Two patients in the ketamine group and one in the morphine group experienced brief desaturation episodes. There were no statistically significant differences with respect to changes in vital signs and need for rescue medication.

CONCLUSION

SDK administered at 0.3 mg/kg over 15 min provides analgesic efficacy comparable to morphine for short-term treatment of acute pain in the geriatric ED patients but results in higher rates of psychoperceptual adverse effects. ClinicalTrials.gov Registration #: NCT02673372.

Intranasal Ketamine Administration for Narcotic Dose Decrement in Patients Suffering from Acute Limb Trauma in Emergency Department: a Double-Blind Randomized Placebo-Controlled Trial

Introduction:

pain management is an important and challenging issue in emergency medicine. Despite the conduct of several studies on this topic, pain is still handled improperly in many cases.

Objective:

This study investigated the effectiveness of low-dose IN ketamine administration in reducing the need for opiates in patients in acute pain resulting from limb injury.

Method:

This randomized, double-blind, placebo-controlled trial was conducted to assess the possible effect of low-dose intranasal (IN) ketamine administration in decreasing patients' narcotic need. Patients in emergency department suffering from acute isolated limb trauma were included. One group of patients received 0.5 mg/kg intravenous morphine sulfate and 0.02 ml/kg IN ketamine. The other group received the same dose of morphine sulfate and 0.02 ml/kg IN distilled water. Pain severity was measured using the 11 points numerical rating scale at 0, 10, 30, 60, 120, and 180 minutes.

Results:

Ninety-one patients with mean age of 31.59 ± 11.33 years were enrolled (38.8% female). The number of requests for supplemental medication was significantly lower in patients who received ketamine (12 patients (30%)) than those who received placebo (27 patients (67.5%)) (p = 0.001).

Conclusion:

It is likely that low-dose IN ketamine is effective in reducing the narcotic need of patients suffering from acute limb trauma.

Ketamine as an Analgesic Adjuvant in Adult Trauma Intensive Care Unit Patients With Rib Fracture

Background: Rib fracture associated pain is difficult to control. There are no published studies that use ketamine as a therapeutic modality to reduce the amount of opioid to control rib fracture pain. Objective: To examine the analgesic effects of adjuvant ketamine on pain scale scores in trauma intensive care unit (ICU) rib fracture. Methods: This retrospective, case-control cohort chart review evaluated ICU adult patients with a diagnosis of ≥1 rib fracture and an Injury Severity Score >15 during 2016. Patients received standard-of-care pain management with the physician’s choice analgesics with or without ketamine as a continuous, fixed, intravenous infusion at 0.1 mg/kg/h. Results: A total of 15 ketamine treatment patients were matched with 15 control standard-of-care patients. Efficacy was measured via Numeric Pain Scale (NPS)/Behavioral Pain Scale (BPS) scores, opioid use, and ICU and hospital length of stay. Safety of ketamine was measured by changes in vital signs, adverse effects, and mortality. Average NPS/BPS, severest NPS/BPS, and opioid use were lower in the ketamine group than in controls (NPS: 4.1 vs 5.8, P < 0.001; severest NPS: 7.0 vs 8.9, P = 0.004; opioid use: 2.5 vs 3.5 mg morphine equivalents/h/d, P = 0.015). No difference was found between the cohort’s length of stay or mortality. Average diastolic blood pressure was higher in the treatment group versus the control group (75.3 vs 64.6 mm Hg, P = 0.014). Conclusion: Low-dose ketamine appears to be a safe and effective adjuvant option to reduce pain and decrease opioid use in rib fracture.

Continuous Intravenous Sub-Dissociative Dose Ketamine Infusion for Managing Pain in the Emergency Department

Introduction

Our objective was to describe dosing, duration, and pre- and post-infusion analgesic administration of continuous intravenous sub-dissociative dose ketamine (SDK) infusion for managing a variety of painful conditions in the emergency department (ED).

Methods

We conducted a retrospective chart review of patients aged 18 and older presenting to the ED with acute and chronic painful conditions who received continuous SDK infusion in the ED for a period over six years (2010–2016). Primary data analyses included dosing and duration of infusion, rates of pre- and post-infusion analgesic administration, and final diagnoses. Secondary data included pre- and post-infusion pain scores and rates of side effects.

Results

A total of 104 patients were enrolled in the study. Average dosing of SDK infusion was 11.26 mg/hr, and the mean duration of infusion was 135.87 minutes. There was a 38% increase in patients not requiring post-infusion analgesia. The average decrease in pain score was 5.04. There were 12 reported adverse effects, with nausea being the most prevalent.

Conclusion

Continuous intravenous SDK infusion has a role in controlling pain of various etiologies in the ED with a potential to reduce the need for co-analgesics or rescue analgesic administration. There is a need for more robust, prospective, randomized trials that will further evaluate the analgesic efficacy and safety of this modality across a wide range of pain syndromes and different age groups in the ED.

Sub-dissociative dose ketamine administration for managing pain in the emergency department

BACKGROUND

We describe our experience of utilizing sub-dissociative dose ketamine (SDK) in managing a variety of acute and chronic painful conditions in the emergency department (ED).

METHODS

A descriptive study was conducted in our ED over a period of seven years (2010-2016) by retrospectively reviewing charts of patients aged 18 and older presenting to the ED with painful complaints and receiving SDK analgesia. Primary data analyses included type of SDK administration (intravenous push [IVP], short-infusion [SI] or continuous infusion [CI]), dosing, rates of analgesic utilization before and after SDK administration, and adverse effects.

RESULTS

Three hundred sixty-two patients were enrolled in the study. Mean ketamine doses given by IVP, SI and CI were 26.3 mg, 23.4 mg, and 11.3 mg. The mean duration of CI was 135.87 minutes. The percentage of patients not requiring post-SDK analgesia increased by 16%, 18%, and 37% in IVP, SI and CI groups. Adverse effects were recorded for 13% of patients.

CONCLUSION

SDK administered by IVP, SI, and CI in the ED for a variety of painful conditions is a feasible analgesic modality in the ED that is associated with a decrease in overall requirements of post-ketamine analgesia and opioid sparing.

Can low-dose of ketamine reduce the need for morphine in renal colic? A double-blind randomized clinical trial

BACKGROUND

The combination of morphine with low doses of ketamine (MK) has been utilized in the Emergency Department (ED) compared with morphine and placebo (MP) for the treatment of acute pain in few studies. The purpose of this study was to compare the effect of MP with MK for the treatment of severe pain with renal colic of patients who had been referred to the ED.

METHODS

This study is a double blind randomized clinical trial on patients with severe renal colic pain who were referred to the ED. Patients were enrolled with pain severity of at least 6 of the 10 visual analogue scales (VAS). Patients were divided into two groups: Morphine 0.1mg/kg and placebo (MP group) and morphine 0.1mg/kg and ketamine 0.15mg/kg (MK group). Pain of patients was studied in 10, 30, 60, 90, and 120min after injection.

RESULTS

Totally, 106 patients were enrolled in study groups. Assessment of the average pain during 120min at 10 and 30min after the start in the drug, MK group was significantly lower than the MP group (p=0.019 and p=0.003 respectively).

CONCLUSION

Given that combinations of morphine with low doses of ketamine in patients with renal colic pain causes more pain and morphine consumption reduction then this combination is suggested as an alternative treatment that could be utilized in patients with renal colic.

Systematic review of the use of low-dose ketamine for analgesia in the emergency department

Objectives

The aim of the study is to determine the performance of low-dose ketamine (LDK) as an analgesic for acute pain management in adult patients in the emergency department (ED).

Methods

We systematically reviewed electronic databases, grey literature, conference abstracts, and clinical trial registries. Two independent reviewers identified eligible studies. These selections were subsequently reviewed by one reviewer who identified the final eligible studies, using refined inclusion and exclusion criteria. Our outcome measures included the analgesic effect of LDK, need for rescue analgesia, and neuropsychological adverse events secondary to LDK use. We assessed inter-rater agreement using kappa statistics and proposed a treatment recommendation using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) software. Heterogeneity among studies precluded meta-analysis.

Results

Our electronic search identified 1,408 records; 44 were selected for full evaluation (kappa=0.70), and 8 were included after the final review. All six randomized controlled trials and two observational studies were set in the ED where LDK was administered to adult patients ( >18 years old) exclusively for pain management. All studies had an overall low risk of bias. There was extensive variation in the dose and route of LDK used (0.1-0.7 mg/kg SC/IV/IM), administration protocols, and use of adjunct analgesia. Overall, most studies reported a significant analgesic effect of LDK with occasional need for rescue analgesia and mild-to-moderate adverse events (dizziness, dysphoria, and confusion).

Conclusion

There are moderate to low quality data supporting LDK as an alternative analgesic in the ED with the potential for minimal requirement of rescue analgesia and self-limited neuropsychological adverse events.

Low dose ketamine use in the emergency department, a new direction in pain management

There is a need for alternative non-opioid analgesics for the treatment of acute, chronic, and refractory pain in the emergency department (ED). Ketamine is a fast acting N-methyl-d-aspartate (NMDA) receptor antagonist that provides safe and effective analgesia. The use of low dose ketamine (LDK) (<1mg/kg) provides sub-dissociative levels of analgesia and has been studied as an alternative and/or adjunct to opioid analgesics. We reviewed 11 studies using LDK either alone or in combination with opioid analgesics in the ED. Ketamine was shown to be efficacious at treating a variety of painful conditions. It has a favorable adverse effect profile when given at sub-dissociative doses. Studies have also compared LDK to opioids in the ED. Although ketamine's analgesic effects were not shown to be superior, they were comparable to opioids. LDK has the benefit of causing less respiratory depression. It likely has less wide spread potential for abuse. Nursing protocols for the administration of LDK have been studied. We believe that LDK has the potential to be a safe and effective alternative and/or adjunct to opioid analgesics in the ED. Additional studies are needed to expand upon and determine the optimal use of LDK in the ED.

The use of subdissociative-dose ketamine for acute pain in the emergency department

OBJECTIVES

Ketamine is a well-known anesthetic with its use trailing back to the 1960s. It has antagonistic effects at the N-methyl-d-aspartate receptor. There is emerging literature to suggest the use of subdissociative-dose ketamine (SDDK) for pain reduction. This evidence-based review evaluates the evidence regarding the use of SDDK for acute pain control in the emergency department (ED).

METHODS

The MEDLINE and EMBASE databases were searched. Randomized controlled trials (RCTs) that described or evaluated the use of SDDK for acute pain in the ED were included. Literature was excluded if it was not published in English. Duplicate articles, unpublished reports, abstracts, and review articles were also excluded. Quality assessment and evaluation of literature were evaluated based on the GRADE criteria. The primary outcome of interest in this review was the difference in pain score from baseline to cutoff time as specified in the studies. Secondary outcome measures were the incidence of adverse events and reduction in the amount of adjuvant opioids consumed by patients who received SDDK.

RESULTS

Four RCTs met the inclusion criteria, which enrolled a total of 428 patients. Three adult trials and one pediatric trial were identified. The level of evidence for the individual trials ranged from low to moderate. A significant reduction in pain scores was only found in two of the four trials. One trial found a significant reduction in mean pain scores when ketamine was compared to morphine (p < 0.05). Another trial reported a significant decrease in mean distress scores, favoring SDDK over fentanyl (1.0 vs. 2.7, p < 0.05). One trial found a significant reduction in the amount of morphine consumed, favoring ketamine over placebo (0.14 mg/kg, 95% confidence interval [CI] = 0.13 to 0.16 mg/kg vs. 0.2 mg/kg, 95% CI = 0.18 to 0.22 mg/kg; p < 0.001). An emergence phenomenon was reported in one trial.

CONCLUSIONS

Four RCTs with methodologic limitations failed to provide convincing evidence to either support or refute the use of SDDK for acute pain control in the ED.

Low-Dose Ketamine Infusion for Emergency Department Patients with Severe Pain

OBJECTIVE

Use of low-dose ketamine infusions in the emergency department (ED) has not previously been described, despite routine use in perioperative and other settings. Our hypothesis was that a low-dose ketamine bolus followed by continuous infusion would 1) provide clinically significant and sustained pain relief; 2) be well tolerated; and 3) be feasible in the ED.

METHODS

We prospectively administered 15 mg intravenous ketamine followed immediately by continuous ketamine infusion at 20 mg/h for 1 hour. Optional morphine (4 mg) was offered at 20, 40, and 60 minutes. Pain intensity, vitals signs, level of sedation, and adverse reactions were assessed for 120 minutes.

RESULTS

A total of 38 patients were included with a median initial numerical rating scale (NRS) pain score of 9. At 10 minutes, the median reduction in pain score was 4, with 7 patients reporting a score of 0. At 60 and 120 minutes, 25 and 26 patients, respectively, reported clinically significant pain reduction (decrease NRS score > 3). Heart rate, blood pressure, respiratory rate, and oxygen saturation remained stable. Mild or moderate side effects including dizziness, fatigue, and headache were common. Patient satisfaction was high; 85% reported they would have this medication again for similar pain.

CONCLUSION

A low-dose ketamine infusion protocol provided significant pain relief with mostly mild side effects and no severe adverse events.

Low-dose ketamine improves pain relief in patients receiving intravenous opioids for acute pain in the emergency department: results of a randomized, double-blind, clinical trial

OBJECTIVES

Low-dose ketamine has been used perioperatively for pain control and may be a useful adjunct to intravenous (IV) opioids in the control of acute pain in the emergency department (ED). The aim of this study was to determine the effectiveness of low-dose ketamine as an adjunct to morphine versus standard care with morphine alone for the treatment of acute moderate to severe pain among ED patients.

METHODS

A double-blind, randomized, placebo-controlled trial with three study groups was conducted at a large, urban academic ED over a 10-month period. Eligible patients were 18 to 65 years old with acute moderate to severe pain (score of at least 5 out of 10 on the numerical pain rating scale [NRS] and pain duration < 7 days) who were deemed by their treating physician to require IV opioids. The three study groups were: 1) morphine and normal saline placebo (standard care group), 2) morphine and 0.15 mg/kg ketamine (group 1), or 3) morphine and 0.3 mg/kg ketamine (group 2). Participants were assessed at 30, 60, and 120 minutes after study medication administration and received rescue analgesia as needed to target a 50% reduction in pain. The primary outcome measure of pain relief, or pain intensity reduction, was derived using the NRS and calculated as the summed pain-intensity (SPID) difference over 2 hours. The amount and timing of rescue opioid analgesia was evaluated as a secondary outcome. The occurrence of adverse events was also measured.

RESULTS

Sixty patients were enrolled (n = 20 in each group). There were no differences between study groups with respect to age, sex, race/ethnicity, preenrollment analgesia, or baseline NRS. Over the 2-hour poststudy medication administration period, the SPIDs were higher (greater pain relief) for the ketamine study groups than the control group (standard care 4.0, interquartile range [IQR] = 1.8 to 6.5; group 1 7.0, IQR = 4.3 to 10.8; and group 2 7.8, IQR = 4.8 to 12.8; p < 0.02). The SPIDs for the ketamine groups were similar (p < 0.46). When compared to standard care, group 2 sustained the reduction in pain intensity up to 2 hours, whereas group 1 was similar to standard care by 2 hours. Similar numbers of patients received rescue analgesia: standard care group, seven of 20, 35%; group 1, four of 20, 20%; and group 2, four of 20, 20% (p = 0.48). Among those receiving rescue analgesia, those in the standard care group received analgesia sooner than either low-dose ketamine group, on average. More participants in the low-dose ketamine groups reported dysphoria and dizziness.

CONCLUSIONS

Low-dose ketamine is a viable analgesic adjunct to morphine for the treatment of moderate to severe acute pain. Dosing of 0.3 mg/kg is possibly more effective than 0.15 mg/kg, but may be associated with minor adverse events. Future studies should evaluate additional outcomes, optimum dosing, and use in specific populations.

Sub-dissociative-dose intranasal ketamine for moderate to severe pain in adult emergency department patients

BACKGROUND

There are currently no studies assessing effectiveness of sub-dissociative intranasal (IN) ketamine as the initial analgesic for adult patients in the ED.

OBJECTIVE

The study aims to examine the effectiveness of sub-dissociative IN ketamine as a primary analgesic agent for adult patients in the ED.

METHOD

This is a prospective, observational study of adult ED patients presenting with severe pain (≥6 on 11-point scale at triage). IN ketamine dose was 0.7 mg/kg, with secondary dose of 0.5 mg/kg at 15 min if pain did not improve. After 6 months, initial dose was increased to 1.0 mg/kg with the same optional secondary dose.

PRIMARY OUTCOMES

The primary outcomes are change in VAS rating at 30 min; percentage of patients reporting clinically significant reduction in VAS (≥20 mm) at 30 min; dose resulting in clinically significant pain reduction.

RESULTS

Of the 72 patients available for analysis, median age was 34.5 years and 64% were men. Median initial VAS rating was 76 mm (interquartile range [IQR]: 65-82). Median total dose of IN ketamine for all patients was 0.98 mg/kg (IQR: 0.75-1.15, range: 0.59-1.57). Median reduction in VAS rating at 30 min was 24 mm (IQR: 2-45). Forty (56%, 95% CI: 44.0-66.7) reported VAS reduction ≥20 mm, these patients having had a total median ketamine dose of 0.94 mg/kg (IQR: 0.72-1.04).

CONCLUSION

IN ketamine, at a dose of about 1 mg/kg, was an effective analgesic agent in 56% of study patients. The place of IN ketamine in analgesic guidelines for adults requires further investigation.

Comparison of local anesthetic effects of lidocaine versus tramadol and effect of child anxiety on pain level in circumcision procedure

OBJECTIVE

To compare the local anesthetic effects of tramadol hydrochloride with those of lidocaine in circumcision procedures. We also investigated the effect of child anxiety on pain level.

PATIENTS AND METHODS

A total of 70 children were included in this study. The children were randomized into 3 groups. Group 1 (n = 26) received lidocaine hydrochloride + epinephrine and they underwent circumcision using Ali's clamp(®). Group 2 (n = 35) received lidocaine hydrochloride + epinephrine and group 3 (n = 12) 5% tramadol. The last two groups underwent conventional circumcision.

RESULTS

The mean anxiety score was 22.6. We did not find significant differences in terms of anxiety score among the groups (p = 0.761). When the pain scores of the groups during injection were compared, it was found that there were no significant differences. However, the pain score of the third group was significantly high when it was compared with the first and second group 2 and 10 min after injection. In the correlation analysis, we found a positive correlation between children's anxiety scores and the pain degree during injection (r = 0.373, p = 0.001).

CONCLUSION

Tramadol may not provide effective local anesthesia in male circumcision. The child's anxiety before the circumcision seems to have a negative effect on pain level.

Effective analgesia with low-dose ketamine and reduced dose hydromorphone in ED patients with severe pain

OBJECTIVE

We assessed the analgesic effect and feasibility of low-dose ketamine combined with a reduced dose of hydromorphone for emergency department (ED) patients with severe pain.

METHODS

This was a prospective observational study of adult patients with severe pain at an urban public hospital. We administered 0.5 mg of intravenous (IV) hydromorphone and 15 mg of IV ketamine, followed by optional 1 mg hydromorphone IV at 15 and 30 minutes. Pain intensity was assessed at 12 intervals over 120 minutes using a 10-point verbal numerical rating scale (NRS). Patients were monitored throughout for adverse events. Dissociative side effects were assessed using the side effects rating scale for dissociative anesthetics.

RESULTS

Of 30 prospectively enrolled patients with severe pain (initial mean NRS, 9), 14 reported complete pain relief (NRS, 0) at 5 minutes; the mean reduction in NRS pain score was 6.0 (SD, 3.2). At 15 minutes, the mean reduction in NRS pain score was 5.0 (SD, 2.8). The summed pain intensity difference and percent summed pain intensity difference scores were 25 (95% confidence interval [CI], 21-30) and 58% (95% CI, 49-68) at 30 minutes and 41 (95% CI, 34-48) and 50% (95% CI, 42-58) at 60 minutes, respectively. Most patients (80%) reported only weak or modest side effects. Ninety percent of patients reported that they would have the medications again. No significant adverse events occurred.

CONCLUSIONS

Low-dose ketamine combined with a reduced dose hydromorphone protocol produced rapid, profound pain relief without significant side effects in a diverse cohort of ED patients with acute pain.

Ketamine: use in anesthesia

The role of ketamine anesthesia in the prehospital, emergency department and operating theater settings is not well defined. A nonsystematic review of ketamine was performed by authors from Australia, Europe, and North America. Results were discussed among authors and the final manuscript accepted. Ketamine is a useful agent for induction of anesthesia, procedural sedation, and analgesia. Its properties are appealing in many awkward clinical scenarios. Practitioners need to be cognizant of its side effects and limitations.

Simultaneous population pharmacokinetic modelling of ketamine and three major metabolites in patients with treatment-resistant bipolar depression

AIM

To construct a population pharmacokinetic (popPK) model for ketamine (Ket), norketamine (norKet), dehydronorketamine (DHNK), hydroxynorketamine (2S,6S;2R,6R)-HNK) and hydroxyketamine (HK) in patients with treatment-resistant bipolar depression.

METHOD

Plasma samples were collected at 40, 80, 110, 230 min on day 1, 2 and 3 in nine patients following a 40 min infusion of (R,S)-Ket (0.5 mg kg⁻¹) and analyzed for Ket, norKet and DHNK enantiomers and (2S,6S;2R,6R)-HNK, (2S,6S;2R,6R)-HK and (2S,6R;2R,6S)-HK. A compartmental popPK model was constructed that included all quantified analytes, and unknown parameters were estimated with an iterative two-stage algorithm in ADAPT5.

RESULTS

Ket, norKet, DHNK and (2S,6S;2R,6R)-HNK were present during the first 230 min post infusion and significant concentrations (>5 ng ml⁻¹) were observed on day 1. Plasma concentrations of (2S,6S;2R,6R)-HK and (2S,6R;2R,6S)-HK were below the limit of quantification. The average (S) : (R) plasma concentrations for Ket and DHNK were <1.0 while no significant enantioselectivity was observed for norKet. There were large inter-patient variations in terminal half-lives and relative metabolite concentrations; at 230 min (R,S)-DHNK was the major metabolite in four out of nine patients, (R,S)-norKet in three out of nine patients and (2S,6S;2R,6R)-HNK in two out of nine patients. The final PK model included three compartments for (R,S)-Ket, two compartments for (R,S)-norKet and single compartments for DHNK and HNK. All PK profiles were well described, and parameters for (R,S)-Ket and (R,S)-norKet were in agreement with prior estimates.

CONCLUSION

This represents the first PK analysis of (2S,6S;2R,6R)-HNK and (R,S)-DHNK. The results demonstrate that while norKet is the initial metabolite, it is not the main metabolite suggesting that future Ket studies should include the analysis of the major metabolites.

Stereoselective and regiospecific hydroxylation of ketamine and norketamine

The objective was to determine the cytochrome P450s (CYPs) responsible for the stereoselective and regiospecific hydroxylation of ketamine [(R,S)-Ket] to diastereomeric hydroxyketamines, (2S,6S;2R,6R)-HK (5a) and (2S,6R;2R,6S)-HK (5b) and norketamine [(R,S)-norKet] to hydroxynorketamines, (2S,6S;2R,6R)-HNK (4a), (2S,6R;2R,6S)-HNK (4b), (2S,5S;2R,5R)-HNK (4c), (2S,4S;2R,4R)-HNK (4d), (2S,4R;2R,4S)-HNK (4e), (2S,5R;2R,5S)-HNK (4f). The enantiomers of Ket and norKet were incubated with characterized human liver microsomes (HLMs) and expressed CYPs. Metabolites were identified and quantified using LC/MS/MS and apparent kinetic constants estimated using single-site Michaelis-Menten, Hill or substrate inhibition equation. 5a was predominantly formed from (S)-Ket by CYP2A6 and N-demethylated to 4a by CYP2B6. 5b was formed from (R)- and (S)-Ket by CYP3A4/3A5 and N-demethylated to 4b by multiple enzymes. norKet incubation produced 4a, 4c and 4f and minor amounts of 4d and 4e. CYP2A6 and CYP2B6 were the major enzymes responsible for the formation of 4a, 4d and 4f, and CYP3A4/3A5 for the formation of 4e. The 4b metabolite was not detected in the norKet incubates. 5a and 4b were detected in plasma samples from patients receiving (R,S)-Ket, indicating that 5a and 5b are significant Ket metabolites. Large variations in HNK concentrations were observed suggesting that pharmacogenetics and/or metabolic drug interactions may play a role in therapeutic response.

Effect of ketamine pretreatment for anaesthesia in patients undergoing percutaneous transluminal balloon angioplasty with continuous remifentanil infusion

BACKGROUND

An appropriate level of sedation and pharmacological assist are essential during percutaneous transluminal balloon angioplasty (PTA). Ketamine provides good analgesia while preserving airway patency, ventilation, and cardiovascular stability with an opioid sparing effect suggesting that it would be ideal in combination with remifentanil and midazolam in spontaneously breathing patients. We evaluated the effect of a small dose of ketamine added to midazolam and remifentanil on analgesia/sedation for PTA procedures.

METHODS

Sixty-four patients receiving PTA were enrolled. The Control group received midazolam 1.0 mg i.v. and continuous infusion of remifentanil 0.05 µg/kg/min. The Ketamine group received, in addition, an intravenous bolus of 0.5 mg/kg ketamine. Patients' haemodynamic data were monitored before remifentanil infusion, 5 min after remifentanil infusion, at 1, 3, 5, 30 min after incision, and at admission to the recovery room. Verbal numerical rating scales (VNRS) and sedation [OAA/S (Observer's Assessment of Alertness/Sedation)] scores were also recorded.

RESULTS

The VNRS values at 1, 3, and 5 min after incision and OAA/S scores at 5 min after remifentanil infusion, and 1, 3, and 5 min after incision were lower in the Ketamine group than in the Control group. In the Control group, the VNRS value at 1 min after incision significantly increased and OAA/S values at 3, 5, and 30 min after incision significantly decreased compared to baseline values, while there were no significant changes in the ketamine group.

CONCLUSIONS

A small dose of ketamine as an adjunct sedative to the combination of midazolam and remifentanil produced a better quality of sedation and analgesia than without ketamine and provided stable respiration without cardiopulmonary deterioration.

Effect of adding ketamine to pethidine on postoperative pain in patients undergoing major abdominal operations: a double blind randomized controlled trial

To determine the effect of adding ketamine to pethidine in reducing post-operative pain in patients undergoing major abdominal operations, in a double blind randomized controlled trial, 100 patients aged 15-60 years who were candidate for elective major abdominal surgery allocated into two groups of pethidine + ketamine group (5 mg pethidine and 0.25 mg kg(-1) ketamine) or pethidine and placebo group (10 mg pethidine and NS) according to the regimen prescribed in postanesthesia care unit. Severity of pain (using visual analogue scale), prescribed dose of pethidine and side effects were recorded until 24 h after operation. Regarding post-operative pain, pethidine + ketamine group showed significant lower scores in all the times except 0 min, 2, 6 and 16 h. Nausea was significantly less frequent amongst pethidine + placebo group at times of 0, 15, 30 and 45 min (p < 0.05). Comparison of two groups did not show significant differences in prescribed pethedine dose in 0, 9, 12, 16, 20 and 24 h (p > 0.05). Yet, the mean dose of administered pethidine as rescue analgesic was significant lower in pethidine + ketamine group compared to pethidine + placebo group (112 +/- 31.5 mg vs. 133.5 +/- 24.5 mg, p < 0.001). In conclusion, our results showed that co-administration of ketamine and pethidine in postanesthesia care unit will improve postoperative pain and reduce narcotic consumption. It may, however, increase rate of postoperative nausea in the first hour after operation.