Ketamine as Adjuvant Analgesic to Opioids: A Quantitative and Qualitative Systematic Review

Ketamine intolerance in patients on enhanced recovery after surgery protocols undergoing colorectal operations

BACKGROUND

Ketamine is used in enhanced recovery after surgery (ERAS) protocols because of its beneficial antihyperalgesic and antitolerance effects. However, adverse effects such as hallucinations, sedation, and diplopia could limit ketamine's utility. The main objective of this study was to identify rates of ketamine side effects in postoperative patients after colorectal surgery and, secondarily, to compare short-term outcomes between patients receiving ketamine analgesia and controls.

METHODS

This was a retrospective observational cohort study. Subjects were adults who underwent ERAS protocol-guided colorectal surgery at a large, integrated health system. Patients were grouped into ketamine-receiving and preketamine cohorts. Patients receiving ketamine were divided into tolerant and intolerant groups. Propensity score-adjusted models tested multivariate associations of ketamine tolerance/intolerance vs control group.

RESULTS

A total of 732 patients underwent colorectal surgery within the ERAS program before ketamine's introduction (control). After ketamine's introduction, 467 patients received the medication. Intolerance was seen in 29% of ketamine recipients, and the most common side effect was diplopia. Demographics and surgical variables did not differ between cohorts. Multivariate models revealed no significant differences in hospital stays. Pain scores in the first 24 hours after surgery were slightly higher in patients receiving ketamine. Opiate consumption after surgery was lower for both ketamine tolerant and ketamine intolerant cohorts than for controls.

CONCLUSION

Rates of ketamine intolerance are high, which can limit its use and potential effectiveness. Ketamine analgesia significantly reduced opiate consumption without increasing hospital stays after colorectal surgery, regardless of whether it was tolerated.

The Role of Ketamine as a Component of Multimodal Analgesia in Burns: A Retrospective Observational Study

Background: Burn wound dressing and debridement are excruciatingly painful procedures that call for appropriate analgesia-typically multimodal. Better post-procedural pain management, less opioid use, and consequently fewer side effects, which could prolong recovery and increase morbidity, are all benefits of this type of analgesia. Intravenously administered ketamine can be effective as monotherapy or in combination with opioids, especially with procedural sedation such as in burn wound dressing. Methods: This observational study investigated the effect of ketamine administered in subanesthetic doses combined with opioids during burn wound dressing. The study was conducted from October 2018 to October 2021. A total of 165 patients met the inclusion criteria. A total of 82 patients were in the ketamine group, while 83 patients were dressed without ketamine. The main outcome was the effect of ketamine on intraprocedural opioid consumption. The secondary outcome included the effect of ketamine on postprocedural pain control. Results: Patients dressed with ketamine were significantly older (p = 0.001), while the mean doses of intraoperatively administered propofol and fentanyl were significantly lower than in patients dressed without ketamine (150 vs. 220 mg, p < 0.001; and 0.075 vs. 0.150 mg, p < 0.001; respectively). Conclusions: Ketamine was an independent predictor of lower intraoperative fentanyl consumption, according to the multivariate regression analysis (p = 0.015). Contrarily, both groups of patients required postoperative tramadol treatment, while intraoperative ketamine administration had no beneficial effects on postoperative pain management.

Pain Control for Sickle Cell Crisis, a Novel Approach? A Retrospective Study

Background and Objectives: Pain management poses a significant challenge for patients experiencing vaso-occlusive crisis (VOC) in sickle cell disease (SCD). While opioid therapy is highly effective, its efficacy can be impeded by undesirable side effects. Local regional anesthesia (LRA), involving the deposition of a perineural anesthetic, provides a nociceptive blockade, local vasodilation and reduces the inflammatory response. However, the effectiveness of this therapeutic approach for VOC in SCD patients has been rarely reported up to now. The objective of this study was to assess the effectiveness of a single-shot local regional anesthesia (LRA) in reducing pain and consequently enhancing the management of severe vaso-occlusive crisis (VOC) in adults with sickle cell disease (SCD) unresponsive to conventional analgesic therapy. Materials and Methods: We first collected consecutive episodes of VOC in critical care (ICU and emergency room) for six months in 2022 in a French University hospital with a large population of sickle cell patients in the West Indies population. We also performed a systematic review of the use of LRA in SCD. The primary outcome was defined using a numeric pain score (NPS) and/or percentage of change in opioid use. Results: We enrolled nine SCD adults (28 years old, 4 females) for ten episodes of VOC in whom LRA was used for pain management. Opioid reduction within the first 24 h post block was -75% (50 to 96%). Similarly, the NPS decreased from 9/10 pre-block to 0-1/10 post-block. Five studies, including one case series with three patients and four case reports, employed peripheral nerve blocks for regional anesthesia. In general, local regional anesthesia (LRA) exhibited a reduction in pain and symptoms, along with a decrease in opioid consumption post-procedure. Conclusions: LRA improves pain scores, reduces opioid consumption in SCD patients with refractory pain, and may mitigate opioid-related side effects while facilitating the transition to oral analgesics. Furthermore, LRA is a safe and effective procedure.

Ketamine in Trauma: A Literature Review and Administration Guidelines

Ketamine is a phencyclidine (PCP) derivative, which primarily acts as a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. Ketamine serves as an analgesic and a dissociative sedative that produces potent analgesia, sedation, and amnesia while preserving spontaneous respiratory drive. It is rapidly gaining acceptance in the management of pain as multiple studies have demonstrated its reliable efficacy and a wide margin of safety. This article reviews some of these studies, the history of ketamine, and its pharmacological and pharmacokinetic properties. The article also discusses the use of ketamine in the trauma setting, including joint reductions, procedures, sedation, and pain control, as well as dosing recommendations.

The Pain Management of Trauma Patients in the Emergency Department

The vast majority of injured patients suffer from pain. Systematic assessment of pain on admission to the emergency department (ED) is a cornerstone of translating the best treatment strategies for patient care into practice. Pain must be measured with severity scales that are validated in clinical practice, including for specific populations (such as children and older adults). Although primary care ED of trauma patients focuses on resuscitation, diagnosis and treatment, pain assessment and management remains a critical element as professionals are not prepared to provide effective and early therapy. To date, most EDs have pain assessment and management protocols that take into account the patient's hemodynamic status and clinical condition and give preference to non-pharmacological approaches where possible. When selecting medications, the focus is on those that are least disruptive to hemodynamic status. Pain relief may still be necessary in hemodynamically unstable patients, but caution should be exercised, especially when using opioids, as absorption may be impaired or shock may be exacerbated. The analgesic dose of ketamine is certainly an attractive option. Fentanyl is clearly superior to other opioids in initial resuscitation and treatment as it has minimal effects on hemodynamic status and does not cause central nervous system depression. Inhaled analgesia techniques and ultrasound-guided nerve blocks are also increasingly effective solutions. A multimodal pain approach, which involves the use of two or more drugs with different mechanisms of action, plays an important role in the relief of trauma pain. All EDs must have policies and promote the adoption of procedures that use multimodal strategies for effective pain management in all injured patients.

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.

Role of the mesolimbic dopamine pathway in the antidepressant effects of ketamine

Depression is a complex and highly heterogeneous disorder which diagnosis is based on an exceedingly variable set of clinical symptoms. Current treatments focus almost exclusively on the manipulation of monoamine neurotransmitter systems, but despite considerable efforts, these remain inadequate for a significant proportion of those afflicted by the disorder. The emergence of racemic (R, S)-ketamine as a fast-acting antidepressant has provided an exciting new path for the study of major depressive disorder (MDD) and the search for better therapeutics for its treatment. Previous work suggested that ketamine's mechanism of action is primarily mediated via blockaded of N-methyl-d-aspartate (NMDA) receptors, however, this is an area of active research and clinical and preclinical evidence now indicate that ketamine acts on multiple systems. The last couple of decades have cemented the mesolimbic dopamine reward pathway's involvement in the pathogenesis of MDD and related mood disorders. Exposure to negative stress dysregulates dopamine neuronal activity disrupting reward and motivational processes resulting in anhedonia (lack of pleasure), a hallmark symptom of depression. Although the mechanism(s) underlying ketamine's antidepressant activity continue to be elucidated, current evidence indicate that its therapeutic effects are mediated, at least in part, via long-lasting synaptic changes and subsequent molecular adaptations in brain regions within the mesolimbic dopamine system. Notwithstanding, ketamine is a drug of abuse, and this liability may pose limitations for long term use as an antidepressant. This review outlines the current knowledge of ketamine's actions within the mesolimbic dopamine system and its abuse potential. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

Comparison of the Effect of Intravenous Fentanyl with Low-Dose Ketamine on Pain Relief in Patients Taking Methadone and Suffering from Limb Fractures

Background

Given the significance of pain control in addicted patients and the prominence of not using opioids due to patient's drug dependence, the present study aimed at comparing and evaluating the effect of intravenous fentanyl with low-dose ketamine on pain relief in patients taking methadone and suffering from limb fractures.

Materials and Methods

The present double-blind randomized clinical trial was performed on 100 patients taking methadone and suffering from limb fractures. The patients were divided into two groups receiving 1 μg/kg single dose of fentanyl and 0.3 mg/kg single dose of ketamine (low-dose ketamine). Patients' pain scores and the incidence rate of complications were recorded before the intervention, and 15, 30, and 60 min after drug administration and were then compared between the two groups.

Results

The mean pain score of patients 15 min after the intervention was significantly lower in the low-dose ketamine group with a mean of 2.50 ± 1.34 as compared with the fentanyl group with a mean of 7.10 ± 1.43 (P < 0.001). However, the mean pain score was not significantly different between the two groups 30 and 60 min after the intervention (P > 0.05). In addition, the incidence rate of complications was not significantly different between the two groups (P > 0.05).

Conclusion

According to the results of this study, low-dose ketamine as compared with fentanyl relieves pain in the mentioned patients with a faster effect and in a shorter time although no difference can be found between the pain scores of the two groups 30 and 60 min after the intervention.

Meta-analysis of the efficacy of ketamine in postoperative pain control in adolescent idiopathic scoliosis patients undergoing spinal fusion

PURPOSE

In this meta-analysis, we aim to compare ketamine use versus a control group (saline solution) during induction of anesthesia in adolescent idiopathic scoliosis patients undergoing fusion surgery in terms of postoperative opioid consumption, pain control, and side effects.

METHODS

A PubMed search of studies published over the last 20 years using the descriptor/terms "ketamine AND scoliosis" was performed. Baseline characteristics of each article were obtained and efficacy measures analyzed (morphine equivalent treatment at 24, 48, and 72 h postoperatively, complications (vomiting/nausea and pruritus), length of hospital stay (days); and pain score (VAS)) (Review Manager 5.4 software package).

RESULTS

Five randomized clinical trials were included. Morphine administration showed statistically significant differences at 24 and 48 h (MD - 0.15, 95% CI - 0.18 to - 0.12) and (MD - 0.26, 95% CI - 0.31 to - 0.21) between the ketamine and control (saline solution), respectively. No intergroup differences were found regarding nausea/vomiting and pruritus (OR 0.77, 95% CI 0.35 to 1.67) and (OR 0.71, 95% CI 0.31 to 1.62), respectively, same as for the pain score (MD - 0.75, 95% CI - 1.71 to 0.20).

CONCLUSIONS

The use intraoperative and postoperative continuous low doses of ketamine significantly reduces opioid use throughout the first 48 h in patients with AIS who undergo posterior spinal fusion.

Flail chest injury-changing management and outcomes

PURPOSE

The purpose of this study was to assess trends in management of flail chest injuries over time and to determine impact on patient outcomes.

METHODS

A retrospective review of data from a prospectively collated database of all trauma patients admitted to a level 1 trauma service in Victoria was conducted. All trauma patients admitted to the hospital between July 2008 and June 2020 with an Abbreviated Injury Scale (AIS) code for flail chest injury were included.

RESULTS

Our study included 720 patients, mean age was 59.5 ± 17.3 years old, and 76.5% of patients were male. Length of ICU stay decreased on average by 9 h each year. Regional anaesthesia use increased by 15% per year (0% in 2009 to 36% in 2020) (p < 0.001). Surgical stabilisation of rib fractures increased by 16% per year (2.9% in 2009 to 22.3% in 2020) (p = 0.006). The use of invasive ventilation decreased by 14% per year (70% in 2008 to 27% in 2020) (p < 0.001), and invasive ventilation time decreased by 8 h per year (p = 0.007).

CONCLUSION

Over the past decade, we have seen increasing rates of regional anaesthesia and surgical rib fixation in the management of flail chest. This has resulted in lower requirements for and duration of invasive mechanical ventilation and intensive care unit stay but has not impacted mortality in this patient cohort.

Comparative Efficacy and Safety of 11 Drugs as Therapies for Adults With Neuropathic Pain After Spinal Cord Injury: A Bayesian Network Analysis Based on 20 Randomized Controlled Trials

Objective

To provide an updated analysis of the efficacy and safety of drugs for the management of neuropathic pain (NP) after spinal cord injury (SCI) based on Bayesian network analysis.

Methods

A Bayesian network meta-analysis of literature searches within PubMed, Cochrane Library, Embase, and Web of Science databases from their inception to February 21 2021 was conducted without language restrictions. Paired and network meta-analyses of random effects were used to estimate the total standardized mean deviations (SMDs) and odds ratios (ORs).

Results

A total of 1,133 citations were identified and 20 RCTs (including 1,198 patients) involving 11 drugs and placebos for post-SCI NP selected. The 5 outcomes from all 11 drugs and placebos had no inconsistencies after Bayesian network analysis. BTX-A gave the most effective pain relief for the 4 weeks, following a primary outcome. No significant differences were found among drugs with regard to adverse events of the primary outcome. Gabapentin, BTX-A, and pregabalin were found to be the most helpful in relieving secondary outcomes of mental or sleep-related symptoms with differences in SMDs, ranging from −0.63 to −0.86. Tramadol triggered more serious adverse events than any of the other drugs with differences in ORs ranging from 0.09 to 0.11.

Conclusion

BTX-A, gabapentin, pregabalin, amitriptyline, ketamine, lamotrigine, and duloxetine were all effective for NP management following SCI. Lamotrigine and gabapentin caused fewer side effects and had better efficacy in relieving mental or sleep-related symptoms caused by SCI-related NP. Tramadol, levetiracetam, carbamazepine, and cannabinoids could not be recommended due to inferior safety or efficacy.

Systematic Review Registration

[https://inplasy.com/inplasy-2020-7-0061/], identifier [INPLASY202070061].

Ketamine as a therapeutic agent for depression and pain: mechanisms and evidence

Ketamine is an anesthetic drug which is now used to treat chronic pain conditions and psychiatric disorders, especially depression. It is an N-methyl-D-aspartate (NMDA) receptor antagonist with additional effects on α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, opioid receptors, and monoaminergic receptors. This article focuses on ketamine's role in treating depression and pain, two commonly comorbid challenging conditions with potentially shared neurobiologic circuitry. Many clinical trials have utilized intravenous or intranasal ketamine for treating depression and pain. Intravenous ketamine is more bioavailable than intranasal ketamine and both are effective for acute depressive episodes. Intravenous ketamine is advantageous for post-operative analgesia and is associated with a reduction in total opioid requirements. Few studies have treated chronic pain or concurrent depression and pain with ketamine. Larger, randomized control trials are needed to examine the safety and efficacy of intravenous vs. intranasal ketamine, ideal target populations, and optimal dosing to treat both depression and pain.

The Options for Neuraxial Drug Administration

Neuraxial drug administration, i.e., the injection of drugs into the epidural or intrathecal space to produce anesthesia or analgesia, is a technique developed more than 120 years ago. Today, it still is widely used in daily practice in anesthesiology and in acute and chronic pain therapy. A multitude of different drugs have been introduced for neuraxial injection, only a part of which have obtained official approval for that indication. A broad understanding of the pharmacology of those agents is essential to the clinician to utilize them in a safe and efficient manner. In the present narrative review, we summarize current knowledge on neuraxial anatomy relevant to clinical practice, including pediatric anatomy. Then, we delineate the general pharmacology of neuraxial drug administration, with particular attention to specific aspects of epidural and intrathecal pharmacokinetics and pharmacodynamics. Furthermore, we describe the most common clinical indications for neuraxial drug administration, including the perioperative setting, obstetrics, and chronic pain. Then, we discuss possible neurotoxic effects of neuraxial drugs, and moreover, we detail the specific properties of the most commonly used neuraxial drugs that are relevant to clinicians who employ epidural or intrathecal drug administration, in order to ensure adequate treatment and patient safety in these techniques. Finally, we give a brief overview on new developments in neuraxial drug therapy.

The Impact of Different Antiemetics on the Nausea in Early Postoperative Period After Laparoscopic Holecystectomy

Postoperative nausea and vomiting (PONV) is a patient-important outcome; patients often rate PONV as worse than postoperative pain. This clinical study was aimed to asses the efficiency of standard aniemetics administration separately or in combination in prevention of PONV in patients who underwent to the same surgical procedure - laparoscopic cholecystectomy. Also, this article could provide a novel information about the best choice for prevention and treatment of PONV. This study included 87 patients divided into four groups according to the postoperative phramacological treatment: First group was control group without treatment, Second group was group of patients with ondasetron treatment in postoperative period, Third group was group of patients with ondasetron+dexamethasone treatment, and fourth group was group of patients with dexamethasone treatment in postoperative period for nausea. PONV was distributed in Ondansetron+Dexamethasone group in the lowest percent (4.5%), which means that this conbination of antiemetics was very effective. Than, Dexamethasone group was in relation with low incidence of PONV (14.3%), and after that were Ondansetron and Control groups. Also smokers and males has lower incidence of PONV, especially in combination with Ondansetron+Dexamethasone treatment.

The incidence of PONV is lower in male smokers patients who were underwent to combination of two antiemetics, ondansetron and dexamethasone compared to monotherapy and female non-smokers. Preventive strategies for PONV must include risk stratification followed by prophylactic approach and also testing the newer antiemetics. Because of the high incidence of postoperative nausea and vomiting as a patient-important outcome, the preventive strategies should be considered as serious condition which requires multimodal approach.

Comparing the Effect of Gabapentin, Ketamine, Dexmedetomidine, and Entonox on Pain Control in Burn Wound Dressing

This study aimed to evaluate differences in the experience of pain, nausea, and vomiting, as well as the hemodynamic parameters including heart rate (HR) and blood pressure (BP) in burn patients across four pain treatment groups-i.e., gabapentin, ketamine, dexmedetomidine, and entonox. In a single blinded randomized comparative study, 25 burn patients with second- or third-degree burns between 20% and 50% of their body surface were assigned to different treatment groups by using block randomization, while keeping the investigator blind to the size of the block. We recorded demographics, the hemodynamics, adverse effects, and pain levels before the treatment and again 5, 10, 15, 30, 60, 120, 240, and 360 minutes postadministration of pain medication (after-treatment). Gabapentin ketamine, dexmedetomidine, and entonox had significant effects in treatment of pain in burn patients. Entonox had the best analgesic effect with the least adverse effects and hemodynamic changes. Gabapentin also had good pain management effects; however, it showed less desirable effects on hemodynamic variables. Entonox caused the least amount of hemodynamic changes and the least adverse reactions, but since the medication is delivered by a facemask it limited its application with our patients. Gabapentin offered good benefits but caused a gradual drop in BP and HR and had some unfavorable reactions. However, since it is administered orally and often is cheaper, it could be considered as the drug of choice.

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.

Low-Dose Ketamine Infusion as Adjuvant Therapy during an Acute Pain Crisis in Pediatric Patients

Recent studies in pediatric patients have suggested that ketamine, an N-methyl-D-aspartate receptor (NMDA) antagonist, given at sub-anesthetic doses can effectively decrease pain scores, provide analgesic effects, and in some cases, reduce opioid requirements. Our study aims to assess impact of low-dose ketamine on reducing pain scores and total opioid requirements during an acute pain crisis in pediatric patients. From November 2016 to December 2018, eight patients between the ages of 2 and 17 years admitted to the pediatric intensive care unit (PICU) were treated with LDK infusions to manage severe, opioid-refractory, acute pain crises. Subjective pain scores and total morphine milligram equivalent (MME) intake before, during, and after ketamine infusion were collected through a structured chart review. Overall, the addition of ketamine appeared to reduce subjective pain scores and opioid requirements. Two patients were in palliative care and expired shortly after ketamine was started and two patients were discharged within 48 hours of LDK infusion cessation. Ketamine seemed to reduce heart rate and had no appreciable effect on respiratory rate, blood pressure, or oxygen saturation. Hallucination was reported in one patient which resolved upon dose reduction. LDK infusion could be considered as an adjuvant therapy to optimize pain control in pediatric patients experiencing acute pain crises. Further investigation with a larger patient population is warranted to establish the effects of LDK on pain improvement and reducing total opioid requirements.

Analgesic Effect of Intraoperative Intravenous S-Ketamine in Opioid-Naïve Patients After Major Lumbar Fusion Surgery Is Temporary and Not Dose-Dependent: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Severe pain often accompanies major spine surgery. Opioids are the cornerstone of postoperative pain management but their use can be limited by numerous side effects. Several studies claim that adjuvant treatment with intravenous (IV) ketamine reduces opioid consumption and pain after back surgery. However, the exact role of ketamine for this indication is yet to be elucidated. We compared 2 different doses of S-ketamine with placebo on postoperative analgesic consumption, pain, and adverse events in adult, opioid-naïve patients after lumbar fusion surgery.

METHODS

One hundred ninety-eight opioid-naïve patients undergoing lumbar spinal fusion surgery were recruited to this double-blind trial and randomly assigned into 3 study groups: Group C (placebo) received a preincisional IV bolus of saline (sodium chloride [NaCl] 0.9%) followed by an intraoperative IV infusion of NaCl 0.9%. Both groups K2 and K10 received a preincisional IV bolus of S-ketamine (0.5 mg/kg); in group K2, this was followed by an intraoperative IV infusion of S-ketamine (0.12 mg/kg/h), while in group K10, it was followed by an intraoperative IV infusion of S-ketamine (0.6 mg/kg/h). Postoperative analgesia was achieved by an IV patient-controlled analgesia (IV PCA) device delivering oxycodone. The primary end point was cumulative oxycodone consumption at 48 hours after surgery. The secondary end points included postoperative pain up to 2 years after surgery, adverse events, and level of sedation and confusion in the immediate postoperative period.

RESULTS

The median [interquartile range (IQR)] cumulative oxycodone consumption at 48 hours was 154.5 [120] mg for group K2, 160 [109] mg for group K10, and 178.5 [176] mg for group C. The estimated difference was -24 mg between group K2 and group C (97.5% confidence interval [CI], -73.8 to 31.5; P = .170) and -18.5 mg between group K10 and C (97.5% CI, 78.5-29.5; P = .458). There were no significant differences between groups.Postoperative pain scores were significantly lower in both ketamine treatment groups at the fourth postoperative hour but not later during the 2-year study period.The higher ketamine dose was associated with more sedation. Otherwise, differences in the occurrence of adverse events between study groups were nonsignificant.

CONCLUSIONS

Neither a 0.12 nor a 0.6 mg/kg/h infusion of intraoperative IV S-ketamine was superior to the placebo in reducing oxycodone consumption at 48 hours after lumbar fusion surgery in an opioid-naïve adult study population. Future studies should assess ketamine's feasibility in specific study populations who most benefit from reduced opioid consumption.

Perioperative Intravenous Low-Dose Ketamine Infusion to Minimize Pain for Septorhinoplasty: A Prospective, Randomized, Double-Blind Study

OBJECTIVES

Studies investigating the effects of intravenous (IV) ketamine in pain management after septorhinoplasty is limited. This study aims to evaluate the efficacy of low-dose IV infusion of ketamine on pain scores.

METHODS

This randomized, prospective, double-blind study was conducted with 48 patients who underwent septorhinoplasty. Intravenous ketamine bolus (0.5 mg/kg) was administered to the ketamine group (group K, n = 24) at anesthesia induction, and ketamine infusion was continued (0.25 mg/kg/h) during the surgery. In the control group (group C, n = 24), the same protocol was administered using saline instead of ketamine. Furthermore, 50-mg dexketoprofen trometamol was administered to both groups 30 minutes before the end of the surgery. Then it was repeated at the 12th and 24th hours postoperatively. Pain scores were evaluated with the visual analogue scale. Consumptions intraoperative of opioid and sevoflurane, rescue opioid requirement, patient satisfaction, and side effects were recorded.

RESULTS

Pain scores were significantly lower in group K at all postoperative periods (P < .05). There was no significant difference between the groups in terms of intraoperative sevoflurane and remifentanil consumptions (P > .05). Rescue opioid analgesic requirements were significantly lower in group K than group C (0/24 vs 6/24, respectively; P  = .022). Side effects were similar between the groups (P > .05).

CONCLUSION

We recommend the administration of low-dose ketamine infusion during septorhinoplasty surgery because it reduces the requirement for rescue opioid analgesia and postoperative pain scores.

Postoperative Pain Management in Pediatric Spinal Fusion Surgery for Idiopathic Scoliosis

This article reviews and summarizes current evidence and knowledge gaps regarding postoperative analgesia after pediatric posterior spine fusion for adolescent idiopathic scoliosis, a common procedure that results in severe acute postoperative pain. Inadequate analgesia may delay recovery, cause patient dissatisfaction, and increase chronic pain risk. Despite significant adverse effects, opioids are the analgesic mainstay after scoliosis surgery. However, growing emphasis on opioid minimization and enhanced recovery has increased adoption of multimodal analgesia (MMA) regimens. While opioid adverse effects remain a concern, MMA protocols must also consider risks and benefits of adjunct medications. We discuss use of opioids via different administration routes and elaborate on the effect of MMA components on opioid/pain and recovery outcomes including upcoming regional analgesia. We also discuss risk for prolonged opioid use after surgery and chronic post-surgical pain risk in this population. Evidence supports use of neuraxial opioids at safe doses, low-dose ketorolac, and methadone for postoperative analgesia. There may be a role for low-dose ketamine in those who are opioid-tolerant or have chronic pain, but the evidence for preoperative gabapentinoids and intravenous lidocaine is currently insufficient. There is a need for further studies to evaluate pediatric-specific optimal MMA dosing regimens after scoliosis surgery. Questions remain regarding how best to prevent acute opioid tolerance, opioid-induced hyperalgesia, and chronic postsurgical pain. We anticipate that this timely update will enable clinicians to develop efficient pain regimens and provide impetus for future research to optimize recovery outcomes after spine fusion.

The role of perioperative ketamine in postoperative pain control following spinal surgery

Opioid abuse has rapidly developed into an epidemic across the United States. Patients are often introduced to opioids following surgical procedures-this is particularly relevant following spinal surgery. Surgeons can help reduce this opioid burden by finding alternatives to narcotic analgesia in the postoperative period. One such medication that has shown potential in this role is ketamine, which has been studied in various surgical specialties. A review was performed of current literature regarding ketamine use in the perioperative period specific to spinal surgery. This review focused on prospective randomized control trials; the primary endpoint was opioid consumption in the postoperative period, monitored through patient-controlled analgesia (PCA) use. Both pediatric and adult spinal surgery patients were included; cervical, thoracic, and lumbar procedures were also all included. 10 studies were selected for this reviewed based on inclusion criteria, published between 2004 and 2017. 7 of these studies demonstrated a significant decrease in postoperative opioid use with the integration of ketamine in the perioperative period, while 3 trials showed no significant difference in opioid consumption. There is inherent difficulty in standardizing studies of this nature-dosing protocols, medication timing, and supplemental analgesia were variable throughout the included studies. However, this review of the most up-to-date prospective studies indicate ketamine has potential to play a significant role in reducing opioid requirements following spinal surgery, and further study is warranted in this field.

Intrathecal Morphine Versus Ketamine in Postoperative Pain After Hysterectomy: Double-Blinded, Randomized Clinical Trial

PURPOSE

Abdominal hysterectomy is one of the most commonly performed gynecologic surgical procedures and is frequently associated with moderate to severe pain. The present study compared the effects of morphine and ketamine on postoperative analgesia, hemodynamic stability, and postoperative adverse effects in patients who underwent abdominal hysterectomy.

DESIGN

This randomized controlled trial compares the effects of morphine plus adjuvants to those of ketamine plus adjuvants, administered as spinal anesthetic agents in patients who underwent abdominal hysterectomy.

METHODS

Eighty patients were randomly assigned to two different groups: group M (morphine, 40 mcg) and group K (ketamine, 20 mg); the anesthetic agents were combined with equal quantities of other adjuvants. Postoperative analgesia was evaluated by means of a numeric pain rating scale; adverse effects (pruritus, nausea and vomiting, urinary retention, respiratory depression, and changes in bowel habits) at specific postoperative time intervals of T1 (4 hours), T2 (12 hours), and T3 (24 hours) were documented and compared. Hemodynamic stability was assessed intraoperatively.

FINDINGS

Both groups displayed similar patient characteristics, comorbidities, paravertebral block level, and intraoperative hemodynamics. The present study observed a significant difference in postoperative analgesia between the two groups, 12 hours after the surgery, with group M exhibiting better results, compared with group K (P = .004). The pain scores obtained from group K were consistent with the amount of rescue medication (tramadol) administered to the subjects in the group, which showed a concomitant higher consumption of tramadol, compared with group M (42.5 and 71.8 mg in group M and group K, respectively, P = .011). Group M showed a higher incidence of pruritus, changes in bowel habits, and constipation compared with group K.

CONCLUSIONS

Compared with ketamine, intrathecal morphine obtained better postoperative analgesia up to 12 hours after surgery, with a higher incidence of pruritus without any significant change in other variables.

Management strategies for the treatment and prevention of postoperative/postdischarge nausea and vomiting: an updated review

Postoperative nausea and vomiting (PONV) and postdischarge nausea and vomiting (PDNV) remain common and distressing complications following surgery. The routine use of opioid analgesics for perioperative pain management is a major contributing factor to both PONV and PDNV after surgery. PONV and PDNV can delay discharge from the hospital or surgicenter, delay the return to normal activities of daily living after discharge home, and increase medical costs. The high incidence of PONV and PDNV has persisted despite the introduction of many new antiemetic drugs (and more aggressive use of antiemetic prophylaxis) over the last two decades as a result of growth in minimally invasive ambulatory surgery and the increased emphasis on earlier mobilization and discharge after both minor and major surgical procedures (e.g. enhanced recovery protocols). Pharmacologic management of PONV should be tailored to the patient’s risk level using the validated PONV and PDNV risk-scoring systems to encourage cost-effective practices and minimize the potential for adverse side effects due to drug interactions in the perioperative period. A combination of prophylactic antiemetic drugs with different mechanisms of action should be administered to patients with moderate to high risk of developing PONV. In addition to utilizing prophylactic antiemetic drugs, the management of perioperative pain using opioid-sparing multimodal analgesic techniques is critically important for achieving an enhanced recovery after surgery. In conclusion, the utilization of strategies to reduce the baseline risk of PONV (e.g. adequate hydration and the use of nonpharmacologic antiemetic and opioid-sparing analgesic techniques) and implementing multimodal antiemetic and analgesic regimens will reduce the likelihood of patients developing PONV and PDNV after surgery.

Ketamine reduces remifentanil-induced postoperative hyperalgesia mediated by CaMKII-NMDAR in the primary somatosensory cerebral cortex region in mice

Remifentanil is commonly used clinically for perioperative pain relief, but it may induce postoperative hyperalgesia. Low doses of ketamine have remained a common choice in clinical practice, but the mechanisms of ketamine have not yet been fully elucidated. In this study, we examined the possible effects of ketamine on calcium/calmodulin-dependent protein kinase II α (CaMKIIα) and N-methyl-d-aspartate receptor (NMDAR) subunit NR2B in a mouse model of remifentanil-induced postoperative hyperalgesia (RIPH) in the primary somatosensory cerebral cortex (SI) region. The paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were used to assess mechanical allodynia and thermal hyperalgesia, respectively, before and after intraoperative remifentanil administration. Before surgery, mice received intrathecal injections of the following drugs: ketamine, NMDA, BayK8644 (CaMKII activator), and KN93 (CaMKII inhibitor). Immunofluorescence was performed to determine the anatomical location and expression of activated CaMKIIα, phosphorylated CaMKIIα (p-CaMKIIα). Additionally, western blotting was performed to assess p-CaMKIIα and NMDAR expression levels in the SI region. Remifentanil decreased the PWMT and PWTL at 0.5 h, 2 h, and 5 h and increased p-CaMKIIα expression in the SI region. Ketamine increased the PWMT and PWTL and reversed the p-CaMKIIα upregulation. Both BayK8644 and NMDA reversed the effect of ketamine, decreased the PWMT and PWTL, and upregulated p-CaMKIIα expression. In contrast, KN93 enhanced the effect of ketamine by reducing hyperalgesia and downregulating p-CaMKIIα expression. These results suggested that ketamine reversed RIPH by inhibiting the phosphorylation of CaMKIIα and the NMDA receptor in the SI region in mice.

Effect of Low-Dose Intravenous Ketamine on Prevention of Headache After Spinal Anesthesia in Patients Undergoing Elective Cesarean Section: A Double-Blind Clinical Trial Study

Background

Spinal anesthesia is the most commonly used method for elective cesarean section, which is a popular technique due to its simplicity, reliability, and speed to achieve adequate anesthesia. Headache following dura perforation is the most important delayed complication following spinal and epidural anesthesia.

Objectives

To evaluate the impact of low-dose intravenous ketamine in patients undergoing cesarean section under spinal anesthesia on the prevention of dura perforation headache (PDPH).

Methods

This clinical trial study was performed on 64 pregnant women undergoing cesarean section at Vali-e-Asr Hospital. The patients were divided into two groups. In the case group, 0.15 mg/kg body weight ketamine was injected intravenously and in the control group, normal saline was used as the placebo. The incidence of headache and its severity at one, 4, 12, and 24 hours postoperatively, nausea and its severity were also measured and compared. Independent t-test, Mann-Whitney U and chi-square tests were used. A P value < 0.05 was considered statistically significant.

Results

The data revealed that low dose intravenous ketamine significantly decreased patients’ headaches (P = 0.001), the sensation of pruritus (P = 0.009), and the need for analgesic (P = 0.001). Furthermore, the sensation of postoperative nausea was less in the case group. The patients in the case and control groups had no significant difference in terms of hypertension or bradycardia (P = 0.717 and 0.939, respectively).

Conclusions

The injection of ketamine as a premedication in the cesarean section can reduce the severity of postoperative headache in mothers. Therefore, it is recommended to use ketamine as an anti-headache drug in pregnant women.

Ketamine sensitization: Influence of dose, environment, social isolation and treatment interval

Ketamine is a dissociative anesthetic first developed in the 1960s but is increasingly used at subanesthetic doses for both clinical and non-clinical purposes. There is evidence from human recreational users of compulsive use and addiction. Sensitization is an increase in an effect of a drug with repeated use that is thought to be important in the development of addiction. Research on psychomotor stimulants has shown the development of sensitization in laboratory animals to be modified by factors that influence addiction. In the current paper we describe four experiments on the development of sensitization in laboratory rats aimed at determining if ketamine sensitization is also influenced by factors thought to be important in addiction. Adult, male Sprague-Dawley rats received ketamine (5, 10, 20 or 50 mg/kg i.p.) for five or more days and the development of locomotor sensitization was followed. Experiment 1 examined the ability of low doses of ketamine to produce sensitization and found sensitization at 5, 10 and 20 mg/kg. Experiment 2 examined the influence of environmental context and found that ketamine sensitization (20 mg/kg) was greater when administration occurred in a novel environment (the experimental apparatus) than in home cages. Experiment 3 found that ketamine sensitization (20 mg/kg) did not occur when animals were housed in social isolation but occurred readily in pair-housed animals. Finally, Experiment 4 found that ketamine sensitization (20 or 50 mg/kg) was similar whether drug was administered daily or at 3-day intervals. Together, the results demonstrate that ketamine sensitization is robust and reliable, occurring under a variety of circumstances. Moreover, ketamine sensitization is influenced by factors that influence the development of addiction in humans. The current results may lead to a better understanding of ketamine abuse and addiction and may help inform clinical use of the drug.

Effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro

The combination of morphine and ketamine is considered safe and efficacious in many patients. However, a considerable number of immunomodulatory effects have been reported to be produced by both morphine and ketamine. The aim of the present study was to assess the direct effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro. Venous blood was obtained from patients with refractory cancer pain and peripheral blood mononuclear cells were isolated using the Ficoll-Hypaque density gradient method. Anti-CD3 beads were used to isolate T cells by positive selection. Subsequently, the T cells were treated with vehicle, 200 ng/ml of morphine or 200 ng/ml of morphine + 100 ng/ml ketamine for 24 h, following which the cells were stimulated with anti-CD3 and anti-CD28. Flow cytometric analysis of CD3⁺ T cells, and interleukin (IL)-2 and interferon (IFN)-γ in the supernatant, reverse transcription-quantitative PCR analysis for the detection of IL-2 and IFN-γ and western blotting for the detection of p65 nuclear factor (NF)-κB were performed. In vitro, the CD4⁺ and CD8⁺ T cell counts, CD4⁺/CD8⁺ ratio, secretion of IL-2 and IFN-γ in the supernatant, mRNA expression levels of IL-2 and IFN-γ and expression of p65 NF-κB were significantly decreased following treatment with morphine and morphine + ketamine, compared with results in the control group (all P<0.05). However, there was no significant difference between treatment with morphine and that with morphine + ketamine. Treatment with morphine + ketamine in vitro decreased the immune functions of patients with refractory cancer pain, although the effect of treatment with morphine and a low dose of ketamine did not differ significantly from that with morphine treatment alone.

Comparison of the Analgesic Effect of Intravenous Ketamine versus Intravenous Morphine in Reducing Pain of Renal Colic Patients: Double-Blind Clinical Trial Study

BACKGROUND

The effective relief of renal colic patients with low complications is one of the important concerns of emergency physicians. The aim of this study was to investigate the use of injectable ketamine as an alternative to routine drugs in the relief of pain in patients with renal colic.

METHODS

This double-blind clinical trial was conducted on patients who had suffered kidney pain due to kidney stones in 2017, referred to Ahvaz Imam Khomeini Hospital. Patients were divided into 2 groups: the first group received intravenous ketamine (0.3 mg/kg) and the second group received intravenous morphine (0.1 mg/kg) in a double-blind form. Finally, the mean pain was evaluated before injection, after 10, 20, 30, and 60 minutes as the initial result while the side effects were considered as secondary results.

RESULTS

In this study, 135 patients with renal colic participate in this study. The mean pain at the time of referral to the hospital in the group receiving morphine and ketamine was 9.2 and 9.2, respectively, which did not show any significant difference. Based on these findings, there was no significant difference between the factors evaluated during the study of the two groups. Only in the ketamine group, there were 3 cases of nausea and 1 of vomiting. However, there was a significant increase in the need for additional doses of fentanyl in the morphine recipient group (p = 0.02).

CONCLUSION

The findings suggest that the use of ketamine can produce a more rapid relief effect, and decrease the use of opioids which create various complications, including nausea and vomiting in patients, especially patients with renal colic.

Opioid Use in the Postoperative Arena: Global Reduction in Opioids After Surgery Through Enhanced Recovery and Gynecologic Surgery

Enhanced recovery programs aim to reduce surgical stress to improve the patient perioperative experience. Through a combination of multimodal analgesia and maintaining a physiological state, postoperative recovery is improved. Many analgesic adjuncts are available that improve postoperative pain control and limit opioid analgesia requirements. Adjuncts are often used in combination, but different interventions may be incorporated for patient-specific and procedure-specific needs. Postoperative pain control can be optimized by continuing nonopioid adjuncts, and prescribing opioid analgesia to address breakthrough pain. Prescribing practices should balance optimizing pain relief, minimizing the risk of chronic pain, while limiting the potential for opioid misuse.

Does Sub-Anesthetic Ketamine Provide Postoperative Analgesia for Third Molar Surgery?

PURPOSE

Despite ketamine's effectiveness as an anesthetic and its known analgesic properties, the role of ketamine in postoperative pain after third molar surgery remains unclear. Therefore, this study aimed to investigate whether patients undergoing third molar surgery who received a sub-anesthetic preoperative dose of intravenous ketamine would experience less postoperative pain.

MATERIALS AND METHODS

We implemented a randomized, double-blinded, placebo-controlled trial. The study sample consisted of participants undergoing third molar surgery with procedural sedation anesthesia. Participants were randomized to receive a preoperative intravenous dose of ketamine or placebo, as predictor variables. The primary outcome variable was postoperative pain intensity determined by a 10-point visual analog scale at 6-hour intervals over a period of 48 hours. The secondary outcome variable was the quantity of postoperative non-opioid and opioid consumption. Other variables included the extent and difficulty of surgery performed, patient satisfaction, gender, and age. Data analysis involved descriptive statistics, multivariate analysis, and regression analysis. The P value was set at .05.

RESULTS

A total of 134 participants were randomly enrolled into either the ketamine group (n = 74, 55.2%) or placebo group (n = 60, 44.8%). No statistically significant differences in the distribution of study variables were found between the groups. A small yet statistically significant (P < .05) difference was noted in the median pain score at 6 hours postoperatively, with the ketamine group experiencing more pain. However, no further differences were detected at any postoperative time between the 2 groups. Similar results were obtained after adjusting for age, gender, and surgical difficulty. No difference in the amount of postoperative non-opioid or opioid medication use was found between the 2 groups.

CONCLUSIONS

This study did not find evidence that a preoperative sub-anesthetic dose of ketamine could reduce pain after third molar surgery or have any effects on non-opioid or opioid analgesic consumption. Nevertheless, ketamine remains a valuable option among sedation medications for oral and maxillofacial surgeons.

Postoperative nausea and vomiting in patients undergoing colorectal surgery within an institutional enhanced recovery after surgery protocol: comparison of two prophylactic antiemetic regimens

BACKGROUND

Enhanced recovery protocols (ERP) provide optimal perioperative care for surgical patients. Postoperative nausea and vomiting (PONV) is common after colorectal surgery (CRS). We aim to compare the efficacy of aprepitant to a cost-effective alternative, perphenazine, as components of triple antiemetic prophylaxis in ERP patients.

METHODS

Patients who underwent ERP CRS at a single institution from July 2015 to July 2017 were evaluated retrospectively. Only subjects who received aprepitant (Group 1) or perphenazine (Group 2) preoperatively for PONV prophylaxis were included. Patient characteristics, simplified Apfel PONV scores, perioperative medications, and PONV incidence were compared between the groups. PONV was defined as the need for rescue antiemetics on postoperative days (POD) 0-5.

RESULTS

Five hundred ninety-seven patients underwent CRS of which 498 met the inclusion criteria. Two hundred thirty-one (46.4%) received aprepitant and 267 (53.6%) received perphenazine. The incidence of early PONV (POD 0-1) was comparable between the two groups: 44.2% in Group 1 and 44.6% in Group 2 (P = 0.926). Late PONV (POD 2-5) occurred less often in Group 1 than Group 2, respectively (35.9% vs. 45.7%, P = 0.027). After matching the groups for preoperative, procedural, and anesthesia characteristics (164 pairs), no difference in early or late PONV could be demonstrated between the groups.

CONCLUSIONS

The incidence of PONV remains high despite most patients receiving three prophylactic antiemetic medications. Perphenazine can be considered a cost-effective alternative to oral aprepitant for prophylaxis of PONV in patients undergoing CRS within an ERP.

The efficacy of different modes of analgesia in postoperative pain management and early mobilization in postoperative cardiac surgical patients: A systematic review

Cardiac surgery induces severe postoperative pain and impairment of pulmonary function, increases the length of stay (LOS) in hospital, and increases mortality and morbidity; therefore, evaluation of the evidence is needed to assess the comparative benefits of different techniques of pain management, to guide clinical practice, and to identify areas of further research. A systematic search of the Cochrane Central Register of Controlled Trials, DARE database, Joanna Briggs Institute, Google scholar, PUBMED, MEDLINE, EMBASE, Academic OneFile, SCOPUS, and Academic search premier was conducted retrieving 1875 articles. This was for pain management postcardiac surgery in intensive care. Four hundred and seventy-one article titles and 266 abstracts screened, 52 full text articles retrieved for critical appraisal, and ten studies were included including 511 patients. Postoperative pain (patient reported), complications, and LOS in intensive care and the hospital were evaluated. Anesthetic infiltrations and intercostal or parasternal blocks are recommended the immediate postoperative period (4-6 h), and patient-controlled analgesia (PCA) and local subcutaneous anesthetic infusions are recommended immediate postoperative and 24-72 h postcardiac surgery. However, the use of mixed techniques, that is, PCA with opioids and local anesthetic subcutaneous infusions might be the way to go in pain management postcardiac surgery to avoid oversedation and severe nausea and vomiting from the narcotics. Adequate studies in the use of ketamine for pain management postcardiac surgery need to be done and it should be used cautiously.

Expanding Role of NMDA Receptor Antagonists in the Management of Pain

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

The Expanding Role of Ketamine in the Emergency Department

Patients frequently come to the emergency department for pain. For decades, ketamine has been used in the emergency department for procedural sedation but is now receiving attention as a potential alternative to opioids because of its unique analgesic effects. Additionally, ketamine's dissociative properties have made it a popular choice for sedating profoundly agitated patients. In this narrative review, these new roles for ketamine in the emergency department are discussed.

CE: Original Research: The Efficacy and Safety of an RN-Driven Ketamine Protocol for Adjunctive Analgesia During Burn Wound Care

: Objective: Traditional analgesic regimens often fail to control the severe pain patients experience during burn wound care, and the drugs are frequently administered at doses that can cause oversedation and respiratory depression. Ketamine may be an ideal agent for adjunctive analgesia in such patients because of its unique mechanism of action and lack of association with respiratory depression. This study evaluated the efficacy and safety of a critical care RN-driven protocol for IV ketamine administration during burn wound care.

METHODS

This retrospective cohort study examined all adult burn patients who received ketamine as part of a critical care RN-driven ketamine protocol for burn wound care from September 2011 through September 2013. Efficacy outcomes were opioid and benzodiazepine requirements (expressed as fentanyl and midazolam equivalents, respectively) four hours after ketamine administration compared with four hours before such administration. Safety parameters assessed were neurologic, hemodynamic, and respiratory effects.

RESULTS

Twenty-seven patients received 56 ketamine doses as part of this protocol; the mean (SD) dose was 0.75 (0.35) mg/kg. Twenty patients (74%) were male and seven (26%) were female; mean age was 39 years. The average percentage of total body surface area burned was 23.4%. With the protocol, opioid and benzodiazepine requirements were reduced by 29% and 20%, respectively. One patient experienced an episode of oversedation after concomitant administration of ketamine and fentanyl. No patients experienced neurologic or hemodynamic complications following ketamine administration.

CONCLUSIONS

The administration of ketamine during burn wound care using a critical care RN-driven protocol was associated with reduced opioid and benzodiazepine requirements and few adverse effects. Prospective studies are needed to investigate additional patient outcomes and the independent administration of ketamine by critical care RNs.

Novel Approaches for Treating Pain in Children

PURPOSE OF REVIEW

Good pain management in children, especially those at end of life, is a crucial component of palliative medicine. The current review assesses some of the new and/or innovative ways to manage pain in children. The article focuses on some recent medications/pharmaceutical options such as cannabinoids and also innovative ways to administer medication to children, such as intranasal and inhalation.

RECENT FINDINGS

Current approaches to pain management now include (1) new uses of old drugs such as ketamine and lidocaine, (2) use of new drugs/medications such as cannabinoids, and (3) creative use of old technology such as atomizers, intranasal drops, and inhalation. Typically, novel approaches to care rarely start in pediatrics or palliative care. The current review has presented some new and old drugs being utilized in new and old ways.

Changing from Epidural to Multimodal Analgesia for Colorectal Laparotomy: An Audit

In April 2002 our practice ceased routine use of epidural analgesia for colorectal laparotomy in favour of a six-drug multimodal regimen comprising ketamine, clonidine, morphine, tramadol, paracetamol and a nonsteroidal antiinflammatory drug. The records of 54 patients who received this multimodal analgesia regimen (MM) after April 2002 were compared to the 59 patients who had previously received epidural analgesia (EPI). Patients had the same surgeon and anaesthetist. Daily pain score (verbal rated 0-10) at rest (mean) over the first three postoperative days was satisfactorily low with both MM (1.2 ± 1.2) and EPI (0.4 ± 0.4). Over this period there was little difference between the maximum pain score at rest (MM 2.3 ± 1.9 vs. EPI 2.2 ± 1.7, P=0.58). Major complications and side-effects occurred solely in EPI patients: epidural abscess (1), respiratory depression (2), pneumonia (3), venous thromboembolism (3), delirium (7), high block (7) and motor block (3). Hypotension requiring intervention was 4.8 times more frequent in the EPI group (95% CI 2.1-11). Antiemetic use was similar between groups; on average 13 patients in the MM groups (24%) and 15 patients in the EPI groups (26%) received antiemetics each day. MM patients had shorter anaesthetic preparation time (20±8 min vs. 32±8 min, P<0.001), shorter high-dependency unit stay (0.4 ± 1.2 days vs. 4.5 ± 0.9 days, P <0.001), and shorter hospital stay(10±4 days vs. 13±8 days, P=0.003). In our practice, changing from epidural to multimodal analgesia produced comparable pain relief with reduction in anaesthesia preparation time, high-dependency unit stay and hospital stay and the requirement for staff interventions. There was also a reduction in the incidence of major complications and side-effects.

Pain: Persistent postsurgery and bone cancer-related pain

The generation of neuropathic pain is a complex dynamic process. Factors involved include one or more dysregulated sensory neural pathways; dysregulated activity of specific neurotransmitters, synapses, receptors and cognitive and emotional neural circuits; and the balance between degenerative and regenerative neural events. Risk factors include age, sex, cognition, emotions, genetic polymorphism, previous or ongoing chronic pain conditions and the use of certain drugs. Intense pain experienced before, during and after surgery is a risk factor for the development of central sensitization with consequent persistent postsurgery neuropathic pain. Blockade of N-methyl-D-aspartate receptors with appropriate drugs during and immediately after surgery may prevent persistent postsurgical pain. Most cancers, but particularly malignant metastases in bone, can induce persistent pain. Local factors including direct damage to sensory nerve fibres, infiltration of nerve roots by cancer cells and algogenic biological agents within the microenvironment of the tumour bring about central sensitization of dorsal horn neurons, characterized by neurochemical reorganization with persistent cancer pain. In this article, the clinical features, pathogenesis and principles of management of persistent postsurgery pain and cancer pain are briefly discussed.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

The Effectiveness and Adverse Effects profile of “Burst” Ketamine in Refractory Cancer Pain: The Vcog Pm 1-00 Study

This multi-centre study of adjuvant “burst” ketamine in palliative care in-patients documents its effectiveness, duration of pain relief, and adverse effects (AE) profile. Patients received a three-to-five day continuous subcutaneous infusion (CSCI) of ketamine escalated from 100 to 300 to 500 mg/24 hours if required. When the effective or maximum tolerated dose was attained, the infusion was continued for three days and each patient assessed as a responder or non-responder using strict criteria. The response rate was 22/44 (50 percent), with 4 (9 percent) becoming pain-free. Pain relief lasting two or more weeks was documented in 50 percent of responders. AEs were documented daily using the National Cancer Institute (NCI) Common Toxicity Criteria 0-4 scales. There were 11 grade 3 and 4 neurological AEs. However, no responders elected to cease treatment early due to neurological AEs. We concluded that this protocol in the controlled environment of an in-patient PC unit is relatively safe and simple with reasonable effectiveness.

A comparison of risk of hypotension using standard doses of remifentanil versus dexmedetomidine infusions in adult patients undergoing surgery under general anaesthesia at the Aga Khan University Hospital, Nairobi

Background

Remifentanil and dexmedetomidine are common agents used in general anaesthesia, monitored anaesthesia care and critical care. When combined with inhaled or intravenous anaesthetic agents intra-operatively, they provide analgesia, lower general anaesthetic requirements and provide sedation and analgesia in the peri-operative period if indicated. Pharmacodynamically, they cause hypotension and bradycardia which are reversible if well managed. Past studies of these drugs have shown a significant proportion of patients with hypotension when compared with similar agents or in isolation. This study compares these two drugs on the effect of hypotension when used as adjuncts to general anaesthesia at low dose standard rate of infusions.

Objective

To compare the proportion of hypotension episodes in a group of adult patients receiving dexmedetomidine infusion at 0.4mcg/kg/hr versus a group receiving remifentanil infusion at 0.2mcg/kg/min, severity of hypotension and physician interventions in each group.

Methods

One hundred and four patients scheduled for elective surgery under general anaesthesia were randomized into two groups: Control group; received remifentanil infusion at 0.2mcg/kg/min

Intervention group; received dexmedetomidine at 0.4mcg/kg/hr.

General anaesthesia was standardized in both groups. The patients were blinded to the study. Baseline blood pressures of all patients were determined prior to induction. The patient's demographic characteristics were recorded. The number of patients who developed hypotension, the frequency of hypotension and the physician interventions were recorded and analysed.

Results

The age and gender characteristics were different between the two groups (p values <0.023 and 0.05 respectively) however they did not affect the proportion of patients with hypotension. The weight, baseline pressures and ASA status of the patients within the groups were similar. The operative procedures varied within the groups. General surgery did not influence the outcome of hypotension in both arms. The duration of surgery in remifentanil group exceeded that of Dexmedetomidine p value<0.0005 however the time to the first episode of hypotension was similar between the groups. The episodes of hypotension were fewer in the dexmedetomidine arm and the proportion of patients with hypotension were higher in the remifentanil arm, p value<0.001, R.R 0. = 0.5938, 95% C.I= 0.329–0.819 The physician interventions administered were similar between the two groups except the use of ephedrine between the groups.

Conclusion

Among this population, at standard infusion rates, the proportion of patients that risk hypotension was greater in those undergoing elective surgery receiving remifentanil at 0.2mcg/kg/min than in dexmedetomidine at 0.4mcg/kg/hr under isoflurane based anaesthesia.