Ketamine anesthesia in children--exploring infusion regimens

The safety of repeated ketamine dosing in paediatrics: A systematic review

BACKGROUND

Ketamine is emerging as an effective, rapidly acting antidepressant in adult research. Hypothetical concerns about its long-term safety and impact on the developing brain are limiting its research in children. However, a wealth of paediatric safety and dosing data exists for ketamine, given its extensive use globally as an anaesthetic, analgesic and sedative agent.

AIMS

To evaluate the safety of repeat dosing of ketamine in children.

METHODS

A systematic search of EMBASE, MEDLINE, PsycINFO, Cochrane Library and PubMed from inception to 13 April 2023 was conducted. Included studies were those reporting adverse events when ketamine was given repeatedly to children aged 5-18, for any condition. No language restrictions were applied. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline and Joanna Briggs Institute Critical Appraisal Tools Checklist for study quality assessment were used. The review process was performed independently by two reviewers.

RESULTS

Five observational studies (87 patients) were included. The maximum number of doses per patient was 42, over a maximum of 4 months. There were no serious adverse events. There was no evidence of needing higher doses with time to indicate tolerance. The longest follow-up period was 6 months. There were no long-term consequences (including neurocognitive) reported within this time frame.

CONCLUSIONS

These results suggest that, despite methodological limitations of the studies, ketamine is well tolerated and safe for use in children, even when given repeatedly in regimens analogous to those used for the treatment of depression in adults. This finding supports the expansion of research into the use of ketamine as a novel antidepressant in children.

Anesthesia management of neonates and infants requiring intraoperative neurophysiological monitoring: A concise review

Intraoperative neurophysiological monitoring is currently used to prevent intraoperative spinal cord and nerve injuries during neonatal and infant surgeries. However, its use is associated with some issues in these young children. The developing nervous system of infants and neonates requires higher stimulation voltage than adults to ensure adequate signals, thereby necessitating reduced anesthesia dose to avoid suppressing motor and somatosensory-evoked potentials. Excessive dose reduction, however, increases the risk of unexpected body movement when used without neuromuscular blocking drugs. Most recent guidelines for older children and adults recommend total intravenous anesthesia with propofol and remifentanil. However, the measurement of anesthetic depth is less well understood in infants and neonates. Size factors and physiological maturation cause pharmacokinetics differences compared with adults. These issues make neurophysiological monitoring in this young population a challenge for anesthesiologists. Furthermore, monitoring errors such as false-negative results immediately affect the prognosis of motor and bladder-rectal functions in patients. Therefore, anesthesiologists need to be familiar with the effects of anesthetics and age-specific neurophysiological monitoring challenges. This review provides an update regarding available anesthetic options and their target concentration in neonates and infants requiring intraoperative neurophysiological monitoring.

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.

Perioperative Low-Dose Ketamine for Postoperative Pain Management in Spine Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

Although low-dose ketamine has been shown to be generally beneficial in terms of pain control in a variety of major surgery, there is no consensus regarding the effectiveness of supplemental ketamine analgesic use exclusively in spine surgery. The objective of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to assess the efficacy and safety of perioperative low-dose ketamine for pain management and analgesic consumption in patients undergoing spine surgery.

Methods

A comprehensive literature search was performed for relevant studies using PubMed, EMBASE, Web of Science, and Cochrane Library. Patients who received perioperative low-dose ketamine were compared to the control group in terms of postoperative pain intensity, opioid consumption, and adverse events. Patients were further categorized by ages and administration times for subgroup analysis.

Results

A total of 30 RCTs comprising 1,865 patients undergoing elective spine surgery were included. Significantly lower pain intensity and less opioid consumption at 12 h, 24 h, and 48 h postoperatively and lower incidence of postoperative nausea and vomiting (PONV) were observed in the ketamine group (all P < 0.05). There was no significant difference of central nervous system (CNS) adverse events between groups. However, different efficacy of low-dose ketamine was detected when patients were categorized by ages and administration times.

Conclusion

Perioperative low-dose ketamine demonstrated analgesic and morphine-sparing effect with no increased adverse events after spine surgery. However, this effect was not significant in pediatric patients. Only postoperative or intraoperative and postoperative administration could prolong the analgesic time up to 48 h postoperatively. Further studies should focus on the optimal protocol of ketamine administration and its effect on old age participants.

Total Intravenous Anesthesia with Ketofol versus Combination of Ketofol and Lidocaine for Short-Term Anesthesia in Pediatric Patients; Double Blind, Randomized Clinical Trial of Effects on Recovery

Background: Ketofol admixture has been proposed to be useful for sedation and general anesthesia. The beneficial effect of the combination of ketofol with lidocaine may be a shortened time of anesthesia and recovery period. This study aimed to establish the effect of total intravenous anesthesia (TIVA) with ketofol and ketofol with lidocaine on recovery in children. Methods: Two hundred children from the ages of 1–12 years who underwent short surgical procedures were randomly allocated into two groups. Propofol mixtures (ketofol) were prepared for group l. A ratio of 1:4 of ketofol was used for induction and for the maintenance of anesthesia a ratio of was used 1:7. For the induction and maintenance of anesthesia ketofol with lidocaine (lidoketofol) was used in group II. The McFarlan infusion regimen was used with reduction. The extubating time, anesthesia duration and the length of stay in the post-anesthesia care unit (PACU) were recorded. Results: Extubation time showed to be considerably shorter in the lidoketofol group than in the ketofol group (120 s versus 240 s; p < 0.00001). The anesthesia duration was also significantly shorter in the lidoketofol group (35 min vs. 50 min; p < 0.00001). The lidoketofol group showed to have a lower length of stay in the post-anesthesia care unit (PACU) than the ketofol group (20 min vs. 35 min; p < 0.00001). The lidoketofol group showed lower fentanyl consumption per kg (2.1 µg per kg vs. 2.3 µg per kg; p < 0.056) and lower propofol consumption (6.6 mg per kg vs. 7.6 mg per kg; p < 0.032). Conclusion: The recovery in pediatric anesthesia can improve with usage of TIVA with ketofol plus lidocaine admixture with a reduced McFarlan dose regimen.

Effects on Recovery of Pediatric Patients Undergoing Total Intravenous Anesthesia with Propofol versus Ketofol for Short-Lasting Laparoscopic Procedures

BACKGROUND

Combining ketamine and propofol (ketofol) was suggested as a new concept for sedation and general anesthesia in pediatric populations for various conditions. The aim of the present study was to determine the effect of total intravenous anesthesia (TIVA) with propofol and ketofol on recovery after laparoscopic surgery in pediatric patients.

METHODS

Two hundred children with median age of 5 years who underwent laparoscopic surgery were randomized into two groups. Propofol 1% was used for induction and maintenance of anesthesia in group I, while ketamine-propofol combination (ketofol) was used in group II. Ketamine-propofol combination (ketofol) was prepared in the same applicator for group II. Ketofol ratios of 1:4 and 1:7 were used for induction and maintenance of anesthesia, respectively. A reduced McFarlan infusion dose was used in group I (1.2, 1.0, and 0.8 mL/kg/h for 15, 15, and 30 min, respectively), while a McFarlan infusion dose was used in group II (1.5, 1.3, and 1.1 mL/kg/h for 15, 15, and 30 min, respectively). Extubating time, duration of anesthesia, and length of stay in post-anesthesia care unit (PACU) were recorded.

RESULTS

Extubating time was significantly lower in the ketofol group than in the propofol group (240 s vs. 530 s; p < 0.00001). Significantly shorter duration of anesthesia (47 min vs. 60 min; p < 0.00001) as well as length of stay in the PACU (35 min vs. 100 min; p < 0.00001) were recorded in ketofol compared to the propofol group. Total fentanyl (100 µg (interquartile range, IQR 80, 125) vs. 50 µg (IQR 40, 60); p < 0.00001) and propofol (260 mg (IQR 200, 350) vs. 160 mg (IQR 120, 210); p < 0.00001) consumption per body weight were significantly lower in the ketofol group.

CONCLUSIONS

TIVA with ketamine-propofol combination (ketofol) using a reduced McFarlan dose regimen shortened extubating time, duration of anesthesia, as well as length of stay in the PACU in pediatric anesthesia after laparoscopic surgery.

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.

Subanesthetic ketamine infusions for the management of pediatric pain in non-critical care settings: An observational analysis

BACKGROUND

Guidelines issued by the American Society of Regional Anesthesia and Pain Medicine suggest that ketamine infusions for acute pain management are advantageous as a primary treatment or as an opioid adjunct. Despite significant data regarding its use in adult patients, there remains a paucity of information related to its quality and side effect profile in pediatrics and how it can be effectively used. We aimed to summarize our practice of utilizing ketamine for pediatric pain management in non-critical care settings.

METHODS

Patients aged 0-21 years receiving low-dose ketamine infusions (≤0.3 mg/kg/hour) in inpatient care units over five years were retrospectively analyzed. Demographics, specific quality metrics, and side effects were quantified.

RESULTS

About 172 patients received 270 subhypnotic ketamine infusions. The median duration of the infusions was 63.8 hours and 0.2 mg/kg/hour for the highest dose. The primary indication for ketamine was chronic pain exacerbation (83.3%). Despite similar opioid consumption, there was a significant reduction in mean verbal pain scores before (8.9 ± 1.9, P < .001) and after ketamine (6.5 ± 2.7, P < .001) use. Although there were 52 incidences of some side effect (neurologic excitability [10.4%]; over-sedation [7.4%]; rapid response team alerts [1.1%]), none resulted in termination of the infusion or escalations in care.

CONCLUSION

Ketamine can effectively be used as part of a multimodal analgesic regimen in pediatric patients in non-critical care settings. Our five-year experience using low-dose ketamine infusions highlights an acceptable side effect profile, with no attributable escalations in care or serious adverse events.

Practicalities of Total Intravenous Anesthesia and Target-controlled Infusion in Children

Propofol administered in conjunction with an opioid such as remifentanil is used to provide total intravenous anesthesia for children. Drugs can be given as infusion controlled manually by the physician or as automated target-controlled infusion that targets plasma or effect site. Smart pumps programmed with pharmacokinetic parameter estimates administer drugs to a preset plasma concentration. A linking rate constant parameter (keo) allows estimation of effect site concentration. There are two parameter sets, named after the first author describing them, that are commonly used in pediatric target-controlled infusion for propofol (Absalom and Kataria) and one for remifentanil (Minto). Propofol validation studies suggest that these parameter estimates are satisfactory for the majority of children. Recommended target concentrations for both propofol and remifentanil depend on the type of surgery, the degree of surgical stimulation, the use of local anesthetic blocks, and the ventilatory status of the patient. The use of processed electroencephalographic monitoring is helpful in pediatric total intravenous anesthesia and target-controlled infusion anesthesia, particularly in the presence of neuromuscular blockade.

Comparison of effects of propofol and ketofol (Ketamine-Propofol mixture) on emergence agitation in children undergoing tonsillectomy

BACKGROUND

The aim of this study was to compare the effect of propofol and ketofol (ketamine-propofol mixture) on EA in children undergoing tonsillectomy.

METHOD

In this randomized clinical trial, 87 ASA class I and II patients, aged 3-12 years, who underwent tonsillectomy, were divided into two groups to receive either propofol 100 µg/kg/min (group p, n=44) or ketofol : ketamine 25 µg/kg/min + propofol 75 µg/kg/min (group k, n= 43). Incidence and severity of EA was evaluated using the Pediatric Anesthesia Emergence Delirium (PAED) scales on arrival at the recovery room, and 10 and 30 min after that time.

RESULTS

There was no statistically significant difference in demographic data between the two groups. In the ketofol group, the need for agitation treatment and also mean recovery duration were lower than in the propofol group (30 and 41%, and 29.9 and 32.7 min), without statistically significant difference (P value=0.143 and P value=0.187). Laryngospasm or bronchospasm occurred in 2 patients in each group and bleeding was observed in only one individual in the ketofol group.

CONCLUSION

Infusion of ketofol in children undergoing tonsillectomy provides shorter recovery time and lower incidence of EA despite the non significant difference with propofol.

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.

Prolonged Perioperative Low-Dose Ketamine Does Not Improve Short and Long-term Outcomes After Pediatric Idiopathic Scoliosis Surgery

STUDY DESIGN

A randomized, double-blind, placebo-controlled study, with a six-month follow-up period.

OBJECTIVES

The aim of this study was to test the hypothesis that a 72-hour dose of subanesthetic ketamine in this surgical procedure reduces postoperative morphine use and to assess whether there are fewer adverse effects, if postoperative recovery is faster, if there is less peri-incisional hyperalgesia, or if there is lower incidence of persistent postsurgical pain.

SUMMARY OF BACKGROUND DATA

Tissue injury and high opioid requirements following posterior spinal fusion surgery produce central sensitization, which can in turn be associated with hyperalgesia and chronic pain. Clinical trials involving this type of procedure using subanesthetic ketamine doses have assessed pain and morphine requirements with contradictory results. The effects of prolonged subanesthetic ketamine doses on postoperative recovery, mechanical hyperalgesia, and the incidence of chronic pain are unknown.

METHODS

A total of 48 pediatric patients between 10 and 18 years diagnosed with idiopathic scoliosis were randomized to receive perioperative low-dose ketamine or placebo for 72 hours. They received general anesthesia, intraoperative remifentanil, and morphine postoperatively (patient-controlled analgesia). We measured morphine consumption, pain at rest and during movement (coughing), undesirable effects, and sedation during morphine treatment. The onset of oral intake, ambulation, and hospital stay were recorded. The extent of the peri-incisional hyperalgesia was measured at 72 hours and pain controls were conducted postsurgery.

RESULTS

Primary endpoint results (total cumulative morphine consumption while admitted) were obtained in 44 patients. Results were 2.72 (SD 1.13) in the placebo group and 3.13 (SD 1.13) in the study group (P = 0.2903), with no significant differences. Moreover, differences were not found between the experimental group and the placebo group in the secondary endpoints analyzed.

CONCLUSION

Our findings do not support the routine combining of prolonged subanesthetic ketamine doses with opioids in posterior fusion surgery in children with idiopathic scoliosis.

LEVEL OF EVIDENCE

2.

Metabolism and metabolomics of ketamine: a toxicological approach

Ketamine is a phencyclidine derivative and a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptor for which glutamate is the full agonist. It produces a functional dissociation between the thalamocortical and limbic systems, a state that has been termed as dissociative anaesthesia. Considerable variability in the pharmacokinetics and pharmacodynamics between individuals that can affect dose-response and toxicological profile has been reported. This review aims to discuss pharmacokinetics of ketamine, namely focusing on all major and minor, active and inactive metabolites. Both ketamine optical isomers undergo hepatic biotransformation through the cytochrome P450, specially involving the isoenzymes 3A4 and 2B6. It is first N-demethylated to active metabolite norketamine. Different minor pathways have been described, namely hydroxylation of the cyclohexanone ring of ketamine and norketamine, and further conjugation with glucuronic acid to increase renal excretion. More recently, metabolomics data evidenced the alteration of several biological pathways after ketamine administration such as glycolysis, tricarboxylic acid cycle, amino acids metabolism and mitochondrial β-oxidation of fatty acids. It is expected that knowing the metabolism and metabolomics of ketamine may provide further insights aiming to better characterize ketamine from a clinical and forensic perspective.

Opioid-Sparing Effect of Ketamine in Children: A Meta-Analysis and Trial Sequential Analysis of Published Studies

INTRODUCTION

Reducing postoperative opioid consumption is a priority given its impact upon recovery, and the efficacy of ketamine as an opioid-sparing agent in children is debated. The goal of this study was to update a previous meta-analysis on the postoperative opioid-sparing effect of ketamine, adding trial sequential analysis (TSA) and four new studies.

MATERIALS AND METHODS

A comprehensive literature search was conducted to identify clinical trials that examined ketamine as a perioperative opioid-sparing agent in children and infants. Outcomes measured were postoperative opioid consumption to 48 h (primary outcome: postoperative opioid consumption to 24 h), postoperative pain intensity, postoperative nausea and vomiting and psychotomimetic symptoms. The data were combined to calculate the pooled mean difference, odds ratios or standard mean differences. In addition to this classical meta-analysis approach, a TSA was performed.

RESULTS

Eleven articles were identified, with four added to seven from the previous meta-analysis. Ketamine did not exhibit a global postoperative opioid-sparing effect to 48 postoperative hours, nor did it decrease postoperative pain intensity. This result was confirmed using TSA, which found a lack of power to draw any conclusion regarding the primary outcome of this meta-analysis (postoperative opioid consumption to 24 h). Ketamine did not increase the prevalence of either postoperative nausea and vomiting or psychotomimetic complications.

CONCLUSIONS

This meta-analysis did not find a postoperative opioid-sparing effect of ketamine. According to the TSA, this negative result might involve a lack of power of this meta-analysis. Further studies are needed in order to assess the postoperative opioid-sparing effects of ketamine in children.

Intravenous sub-anesthetic ketamine for perioperative analgesia

Ketamine, an N-methyl-d-aspartate antagonist, blunts central pain sensitization at sub-anesthetic doses (0.3 mg/kg or less) and has been studied extensively as an adjunct for perioperative analgesia. At sub-anesthetic doses, ketamine has a minimal physiologic impact though it is associated with a low incidence of mild psychomimetic symptoms as well as nystagmus and double vision. Contraindications to its use do exist and due to ketamine's metabolism, caution should be exercised in patients with renal or hepatic dysfunction. Sub-anesthetic ketamine improves pain scores and reduces perioperative opioid consumption in a broad range of surgical procedures. In addition, there is evidence that ketamine may be useful in patients with opioid tolerance and for preventing chronic postsurgical pain.

Subanesthetic ketamine infusions for the treatment of children and adolescents with chronic pain: a longitudinal study

BACKGROUND

Chronic pain is common in children and adolescents and is often associated with severe functional disability and mood disorders. The pharmacological treatment of chronic pain in children and adolescents can be challenging, ineffective, and is mostly based on expert opinions and consensus. Ketamine, an N-methyl-D-aspartate receptor antagonist, has been used as an adjuvant for treatment of adult chronic pain and has been shown, in some instances, to improve pain and decrease opioid-requirement. We examined the effects of subanesthetic ketamine infusions on pain intensity and opioid use in children and adolescents with chronic pain syndromes treated in an outpatient setting.

METHODS

Longitudinal cohort study of consecutive pediatric patients treated with subanesthetic ketamine infusions in a tertiary outpatient center. Outcome measurements included self-reported pain scores (numeric rating scale) and morphine-equivalent intake.

RESULTS

Over a 15-month period, 63 children and adolescents (median age 15, interquartile range 12-17 years) with chronic pain received 277 ketamine infusions. Intravenous administration of subanesthetic doses of ketamine to children and adolescents on an outpatient basis was safe and not associated with psychotropic effects or hemodynamic perturbations. Overall, ketamine significantly reduced pain intensity (p < 0.001) and yielded greater pain reduction in patients with complex regional pain syndrome (CRPS) than in patients with other chronic pain syndromes (p = 0.029). Ketamine-associated reductions in pain scores were the largest in postural orthostatic tachycardia syndrome (POTS) and trauma patients and the smallest in patients with chronic headache (p = 0.007). In 37% of infusions, patients had a greater than 20 % reduction in pain score. Conversely, ketamine infusions did not change overall morphine-equivalent intake (p = 0.3).

CONCLUSIONS

These data suggest that subanesthetic ketamine infusion is feasible in an outpatient setting and may benefit children and adolescents with chronic pain. Further, patients with CRPS, POTS, and a history of trauma-related chronic pain are more likely to benefit from this therapeutic modality.

Intra- and postoperative low-dose ketamine for adolescent idiopathic scoliosis surgery: a randomized controlled trial

BACKGROUND

In this randomized controlled trial, we examined whether intra- and postoperative infusion of low-dose ketamine decreased postoperative morphine requirement and morphine-related adverse effects as nausea and vomiting after scoliosis surgery.

METHODS

After IRB approval and informed consent, 36 patients, aged 10-19 years, undergoing posterior correction surgery for adolescent idiopathic scoliosis, were randomly allocated into two groups: intra- and postoperative ketamine infusion at a rate of 2 μg/kg/min until 48 h after surgery (ketamine group, n = 17) or infusion of an equal volume of saline (placebo group, n = 19). All patients were administered total intravenous anesthesia with propofol and remifentanil during surgery and intravenous morphine using a patient-controlled analgesia device after surgery. The primary outcome was cumulative morphine consumption in the initial 48 h after surgery. Pain scores (Numerical Rating Scale, NRS, 0-10), sedation scales, incidence of postoperative nausea and vomiting (PONV), and antiemetic consumption were recorded by nurses blinded to the study protocol for 48 h after surgery.

RESULTS

Patient characteristics did not differ between the two groups. Cumulative morphine consumption for 48 h after surgery was significantly lower in the ketamine group compared to the placebo group (0.89 ± 0.08 mg/kg vs. 1.16 ± 0.07 mg/kg, 95% confidence interval for difference between the means, 0.03-0.48 mg/kg, P = 0.019). NRS pain, sedation scales, and incidence of PONV did not differ between the two groups. Antiemetic consumption was significantly smaller in ketamine group.

CONCLUSIONS

Intra- and postoperative infusion of low-dose ketamine reduced cumulative morphine consumption and antiemetic requirement for 48 h after surgery.

Ketamine Affects In Vitro Differentiation of Monocyte into Immature Dendritic Cells

Background:

Monocytes (MOs) have the unique ability to differentiate into immature dendritic cells (iDCs) (MO→iDC) under the influence of interleukin-4 and granulocyte–monocyte colony-stimulating factor (IL-4&GM-CSF). In this study, the authors investigated the influence of ketamine on the process of MO→iDC.

Methods:

iDCs were cultured from MO obtained from 36 subjects in the presence of IL-4 and GM-CSF and ketamine at 100, 10, and 1 μg/ml for 5 days. In some of the experiments, the authors used nonspecific N-methyl-d-aspartate (NMDA) receptor antagonist MK-801, NMDA, or a neutralizing antibody for transforming growth factor β (TGFβ). The expression of surface markers and functional assays were used to assess the effect of ketamine on IL-4&GM-CSF-stimulated MO. IL-4&GM-CSF-stimulated MO’s supernatants were assessed for cytokine levels.

Results:

Ketamine at 10 μg/ml, and higher concentrations, diminished the expression of CD1a on IL-4&GM-CSF-stimulated MO and retarded both their ability to process DQ ovalbumin and mixed lymphocyte reaction stimulation. The addition of ketamine to IL-4&GM-CSF-differentiated MO resulted in the persistent expression of CD14 and unchanged expression of CD86 and CD206. The phagocytic abilities of IL-4&GM-CSF-differentiated MO were not changed by ketamine. MK-801, a nonselective NMDA agonist, mimicked ketamine’s effect on MO→iDC differentiation. Adding exogenous NMDA to IL-4&GM-CSF-stimulated MO in the presence of ketamine partially restored the level of CD1a+. TGFβ was elevated in supernatants of IL-4&GM-CSF-stimulated MO in the presence of ketamine. Adding neutralizing TGFβ antibody or TGFβR1 blocker (SB431542) resulted in the full recovery of MO→iDC, despite the presence of ketamine.

Conclusions:

Ketamine diminishes the process of MO→iDC in vitro. This is mediated via NMDA-dependent mechanisms and TGFβ.

Intravenous S-ketamine does not inhibit alveolar fluid clearance in a septic rat model

We previously demonstrated that intratracheally administered S-ketamine inhibits alveolar fluid clearance (AFC), whereas an intravenous (IV) bolus injection had no effect. The aim of the present study was to characterize whether continuous IV infusion of S-ketamine, yielding clinically relevant plasma concentrations, inhibits AFC and whether its effect is enhanced in acute lung injury (ALI) which might favor the appearance of IV S-ketamine at the alveolar surface. AFC was measured in fluid-instilled rat lungs. S-ketamine was administered IV over 6 h (loading dose: 20 mg/kg, followed by 20 mg/kg/h), or intratracheally by addition to the instillate (75 µg/ml). ALI was induced by IV lipopolysaccharide (LPS; 7 mg/kg). Interleukin (IL)-6 and cytokine-induced neutrophil chemoattractant (CINC)-3 were measured by ELISA in plasma and bronchoalveolar lavage fluid. Isolated rat alveolar type-II cells were exposed to S-ketamine (75 µg/ml) and/or LPS (1 mg/ml) for 6 h, and transepithelial ion transport was measured as short circuit current (ISC). AFC was 27±5% (mean±SD) over 60 min in control rats and was unaffected by IV S-ketamine. Tracheal S-ketamine reduced AFC to 18±9%. In LPS-treated rats, AFC decreased to 16±6%. This effect was not enhanced by IV S-ketamine. LPS increased IL-6 and CINC-3 in plasma and bronchoalveolar lavage fluid. In alveolar type-II cells, S-ketamine reduced ISC by 37% via a decrease in amiloride-inhibitable sodium transport. Continuous administration of IV S-ketamine does not affect rat AFC even in endotoxin-induced ALI. Tracheal application with direct exposure of alveolar epithelial cells to S-ketamine decreases AFC by inhibition of amiloride-inhibitable sodium transport.

Ketofol dosing simulations for procedural sedation

BACKGROUND

Propofol mixed with racemic ketamine (or "ketofol") is popular for short procedural sedation and analgesia, yet the optimal combination is unknown. We aimed to determine a ketofol dosing regimen for short procedural sedation and analgesia of 5- to 20-minute duration in healthy patients (2-20 y).

METHODS

Pharmacokinetic-pharmacodynamic parameters were used to simulate drug concentration and effect profiles over time for different ketamine-to-propofol ratios (1:1-1:10). The target effect was a Children's Hospital of Wisconsin Sedation Scale score of less than 2. Combined effects were additive, with a propofol EC50 of 1.54 μg/mL (concentration required to produce hypnosis in 50% of patients), a ketamine EC50 of 0.44 μg/mL, and a slope of 5.3. Emergence threshold concentrations for propofol were 2.0 μg/mL in children and 1.8 μg/mL in adults as well as 0.5 μg/mL for ketamine (children and adults). The EC50 for propofol antiemesis was 0.343 μg/mL.

RESULTS

A ketamine-to-propofol ratio of 1:3 was the best combination for intermittent dosing, achieving a rapid onset of a Children's Hospital of Wisconsin Sedation Scale score of less than 2 within 1 minute and a time to emergence of 9 to 19 minutes in all ages after a 10-minute sedation. The optimal ketofol dosing in children (2-11 y) was 0.1 mL/kg initially followed by 0.05 mL/kg at 2 minutes and then 0.025 mL/kg for the subsequent doses. The adults (12-20 y) received 0.05 mL/kg of ketofol initially followed by 0.025 mL/kg for the subsequent doses. These regimens maintain a propofol antiemesis for 30 to 40 minutes after the last dose.

CONCLUSIONS

We suggest an optimal ratio of racemic ketamine to propofol of 1:3 for boluses during short procedures (5-20 minutes). A short ketofol infusion, ratio 1:4, is a suitable alternative to intermittent boluses. Ratios greater than 1:3 result in delayed recovery after 20 minutes.

Dexmedetomidine and ketamine sedation for muscle biopsies in patients with Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) possesses many potential challenges for anesthetic care. Invasive and noninvasive procedures with corresponding sedation or general anesthesia are frequent and necessary for affected patients. There remains a need for a better agent or agents for procedural sedation in patients with comorbid diseases. This study prospectively evaluated a combination of ketamine with two different doses of dexmedetomidine for sedation during muscle biopsy in patients with DMD.

METHODS

Dexmedetomidine 1.0 or 0.5 μg·kg(-1) was administered as a loading dose over 3 min followed by a continuous infusion of 1.0 or 0.5 μg·kg·h(-1). Ketamine (1 mg·kg(-1)) was administered along with the dexmedetomidine loading dose. As the procedure commenced, additional doses of ketamine (0.5 mg·kg(-1)) were administered as needed. Sedation scores, hemodynamic data, operative times, and recovery times were recorded.

RESULTS

The study cohort included a total of 53 bicep, deltoid, or anterior tibialis muscle biopsies in 19 boys including 24 in the dexmedetomidine 1.0 μg·kg(-1) group and 29 in the dexmedetomidine 0.5 μg·kg(-1) group. Mean age and weight were 9.7 ± 1.4 years and 33.3 ± 7.7 kg in the dexmedetomidine 1.0 μg·kg(-1) group and 8.8 ± 1.8 years and 30.2 ± 10.8 kg in the dexmedetomidine 0.5 μg·kg(-1) group. No significant changes in blood pressure were noted. A decrease in heart rate (HR) occurred after the loading dose of dexmedetomidine in both groups. The HR was significantly lower in the dexmedetomidine 1.0 μg·kg(-1) group compared with the dexmedetomidine 0.5 μg·kg(-1) group. Total recovery time to discharge was significantly shorter in the dexmedetomidine 0.5 μg·kg(-1) group than the dexmedetomidine 1.0 μg·kg(-1) group (146 ± 65 vs 174 ± 58 min; P = 0.03), although the total ketamine dose was significantly greater in the dexmedetomidine 0.5 μg·kg(-1) group (3.7 ± 1.0 vs 2.0 ± 0.5 mg·kg(-1); P < 0.01). There were no episodes of apnea or hypoventilation; however, a jaw thrust was needed in one patient in the dexmedetomidine 1.0 μg·kg(-1) group.

CONCLUSION

The combination of dexmedetomidine and ketamine is safe and effective for moderately painful procedures with limited respiratory and cardiovascular effects in a high-risk patient population. Dexmedetomidine 0.5 μg·kg(-1) as a loading dose with ketamine followed by a continuous infusion of dexmedetomidine at 0.5 μg·kg(-1) ·h(-1) achieved an adequate sedation level with shorter total recovery times in the perioperative unit compared with a higher dose regimen of dexmedetomidine (1.0 μg·kg(-1) loading dose followed by an infusion at 1.0 μg·kg(-1) ·h(-1)).

Ketofol simulations for dosing in pediatric anesthesia

BACKGROUND

Propofol mixed with racemic ketamine (or 'ketofol') is popular for short procedural sedation and analgesia. Use is creeping into anesthesia, yet neither the optimal combination nor infusion rate is known. The EC(50) of propofol's antiemetic effect is reported to be 0.343 mg·l(-1), while ketamine analgesia is thought to persist with concentrations above 0.2 mg·l(-1). We aimed to determine a ketofol dosing regimen for anesthesia 30-min and 1.5-h duration in a healthy child that did not unduly compromise recovery.

METHODS

Pharmacokinetic-pharmacodynamic parameters were used to simulate drug concentration and effect profiles over time for different ratios of propofol to ketamine ratios (1 : 1 to 10 : 1) and rates. The target effect was the 95% probability of loss of response to a 5-s transcutaneous tetanus (P05). Combined effects were additive, with a propofol EC(50) of 3.1 mg·l(-1), ketamine EC(50) of 0.64 mg·l(-1), and slope of 5.4. The time to predicted 50% probability of return of this response after ceasing infusion (P(50)) was determined for a 5-year-old 20-kg healthy child.

RESULTS

The addition of ketamine to propofol infused using a manual infusion regimen (loading dose 3 mg·kg(-1), then 15 mg·kg(-1) ·h(-1) for 15 min, 13 mg·kg(-1) ·h(-1) for 15 min, 11 mg·kg(-1) ·h(-1) for 30 min, and 10 mg·kg(-1) ·h(-1) for 1-2 h) caused prolonged postoperative sedation. The P(50) after a 1.5-h infusion using a 1 : 1 mixture was 4.5 h, 2 : 1 mixture was 3.25 h, 5 : 1 mixture was 1.6 h, and 10 : 1 mixture was 40 min. These P(50) estimates could be reduced by slowing administration infusion rates to 20%, 33%, 50%, 67%, 80%, and 90% for mixtures 1 : 1, 2 : 1, 3 : 1, 5 : 1, 6.7 : 1, and 10 : 1, respectively. These rates achieve a P(50) of approximately 20 min for 30-min duration anesthesia and 60 min for 1.5-h duration anesthesia.

CONCLUSIONS

The addition of ketamine to propofol infusion will prolong recovery unless infusion rates are decreased. We suggest an optimal ratio of racemic ketamine to propofol of 1 : 5 for 30-min anesthesia and 1 : 6.7 for 90-min anesthesia. Delivery of these ratios achieves propofol concentrations above an antiemetic threshold for longer than the ketamine concentration above the analgesic threshold during, potentially reducing postoperative nausea incidence.

Prolonged perioperative infusion of low-dose ketamine does not alter opioid use after pediatric scoliosis surgery

BACKGROUND

Opioid consumption after posterior spinal fusion is known to be high and often exceeds those reported in other major surgical procedures. A number of clinical trials provide evidence that the perioperative use of subanesthetic doses of ketamine reduces pain and opioid requirements in some surgical procedures, but the effect of prolonged perioperative low-dose ketamine infusion in patients undergoing posterior spinal fusion for pediatric scoliosis surgery is unknown.

OBJECTIVE

To test the hypothesis that a 72-h perioperative low-dose ketamine infusion would decrease opioid use in pediatric patients undergoing posterior spinal fusion.

METHODS

In a double-blind prospective controlled trial, patients undergoing posterior spinal fusion for scoliosis were randomized to receive perioperative low-dose ketamine or placebo control. Patients received general anesthesia, intraoperative remifentanil, and morphine patient-controlled analgesia postoperatively. Daily opioid consumption, self-reported pain scores, and sedation scores were measured.

RESULTS

Fifty-four patients were enrolled and 50 completed the study. Contrary to our hypothesis, ketamine- and control-treated patients had similar postoperative opioid use, pain scores, and sedation scores measurements. In contrast, ketamine-treated patients required less intraoperative remifentanil compared with control (mean 2.9 mg vs. 4 mg, P = 0.0415). Number of vertebrae instrumented, time between end-of-surgery and 24 h assessment, or remifentanil doses did not impact on postoperative opioid use. Over 96-h postoperatively, morphine-equivalent consumption was lower (-0.40, P = 0.006) and sedation score was higher (0.47, P = 0.0211) in male patients, compared with female patients.

CONCLUSIONS

These findings do not support the use of perioperative low-dose ketamine to decrease opioid use in children with scoliosis undergoing posterior spinal fusion.

Comparison of low-dose ketamine to midazolam for sedation during pediatric urodynamic study

INTRODUCTION

Aim of sedation during pediatric urodynamic studies (UDS) is a calm and cooperative child while not affecting measurements. We compared the effectiveness of midazolam to low-dose ketamine infusion for sedation and their impact on urodynamics.

MATERIALS AND METHODS

ASA-I children undergoing UDS were randomly assigned to group K (ketamine) loading dose (0.25 mg·kg(-1)) followed by infusion of 10-20 μg·kg(-1) ·min(-1) or group M (midazolam) loading dose of (0.02 mg·kg(-1)) followed by 1-2 μg·kg(-1) ·min(-1). The sedation scores and reactivity to catheterization were monitored by Children Hospital of Wisconsin Sedation Scale and Frankl Behavior Rating Scale, respectively. The UDS included two-channel filling cystometry in supine position followed by a free uroflowmetry in sitting position. The UDS was performed and interpreted in accordance with good urodynamic practice guidelines of International Continence Society (2002).

RESULTS

A total of 34 children were enrolled. Group K children (n = 17) attained sedation earlier 6.80 (±3.36) min vs. 9.40 (±2.82) min; (P = 0.03) than group M (n = 17) and also recovered earlier 11.60 (±3.13) min vs. 19.67 (±5.49) min (P = 0.01). Reactivity scores during urinary and rectal catheterization were lower in group K (P = 0.03 and 0.01), respectively. Historical UDS data of 21 participants were available for comparison with effect of medication. None of the study drugs affected UDS parameters significantly.

CONCLUSIONS

Midazolam or low-dose ketamine provide satisfactory sedation during pediatric UDS without impacting urodynamic values.

[Opioid-sparing effect of ketamine during tonsillectomy in children]

INTRODUCTION

In the adult population, Ketamine is currently used as an antihyperalgesic and opioid-sparing agent during the perioperative period. However, for doses of ketamine up to 0.5mg/kg, these effects have not been found in pediatric population. The aim of the present study was to evaluate the efficacy of a preoperative bolus of 1mg/kg of ketamine on postoperative pain intensity and morphine consumption in children undergoing tonsillectomy.

METHODS

We have undertaken a retrospective comparison of 60 consecutive children operated for tonsillectomy in our institution before (first 30 patients) and after (last 30 patients) the introduction of a preoperative bolus of 1mg/kg of ketamine. Data collected were: age, ASA score, dose of intraoperative sufentanil, OPS score during PACU stay and the first postoperative day, morphine consumption during PACU stay and the first postoperative day, psychodysleptic manifestations, pain at first solid oral intake and postoperative respiratory complications or haemorrhage.

RESULTS

No difference was found between the two groups in terms of demographic characteristics. Perioperative doses of sufentanil, postoperative opioid consumption or pain score in PACU or during 24hours were similar between the two groups. The two groups did not differ in terms of pain at first oral intake, or other adverse effects.

CONCLUSION

These results suggest that 1mg/kg of ketamine administered right after anaesthesia induction in children undergoing tonsillectomy did not result in an opioid sparing effect.

Anaesthesia for TMJ Ankylosis with the Use of TIVA, Followed by Endotracheal Intubation

TMJ ankylosis, though it is not common, is an anaesthetic challenge, as it is a difficult airway situation with a moderate to a severely limited mouth opening. Fiber-optic intubation is the gold standard for such cases, but it may not be readily available at all centres. Blind nasal intubation, retro-grade intubation and tracheostomy are the other alternatives, but they require patient co-operation and are associated with considerable morbidity. We are presenting a case of unilateral TMJ ankylosis in a 12 years old boy who was posted for condylectomy and interpositional arthroplasty. He was maintained on TIVA for condylectomy and was then intubated for the remaining procedure. The procedure and the recovery were uneventful.

In vitro and in vivo effects of ketamine on generation and function of dendritic cells

The question about how intravenous anesthetic reagents affect the development and function of dendritic cell subsets still has no comprehensive answers. Bone marrow cells differentiated with FMS-like tyrosine kinase 3 ligand in vitro represented the steady-state dendritic cell subsets. The effects of ketamine on the generation and function of dendritic cell subsets were investigated. We found that dendritic cell subsets responded to the anesthetic reagent ketamine in several aspects: 1) The in vitro and in vivo development of plasmacytoid dendritic cells were inhibited by ketamine at high concentrations; 2) The endocytosis of dendritic cells were not influenced by ketamine at concentrations from 50 - 200 µM; 3) The maturation markers of conventional dendritic cells were not changed by ketamine upon LPS or CpG stimulation, although the cytokines mRNA profiles were affected; 4) The allogenic-stimulatory activity of dendritic cells was suppressed by ketamine. In conclusion, ketamine hampered plasmacytoid dendritic cell subset development both in vivo and in vitro. The dendritic cells maturation and downstream responses towards different toll-like receptor stimuli were differently regulated by ketamine treatment.

Ketamine for perioperative pain management in children: a meta-analysis of published studies

INTRODUCTION

Balanced analgesia, using both opioid and nonopioids agents, has become the standard care for postoperative pain management. Ketamine, a compound with analgesic and antihyperalgesic properties, has been shown to decrease postoperative pain and opioid requirements in adults. The goal of the present meta-analysis was to investigate postoperative analgesic properties of ketamine in pediatric patients.

MATERIAL AND METHODS

A comprehensive literature search was conducted to identify clinical trials that used ketamine as a perioperative analgesic compound in children and infants. Outcomes measured were postoperative analgesic consumption, pain intensity and duration of sensory block (when ketamine was used by caudal route) during the postoperative care unit (PACU) stay and the early postoperative period (6-24 h after leaving the operative room). The data from each trial were combined to calculate the pooled odds ratios or standard mean differences and their 95% confidence intervals.

RESULTS

Thirty-five randomized, blinded controlled studies were retrieved from the literature. Systemic ketamine was effective in decreasing PACU pain intensity and analgesic requirement but failed to influence early (6-24 h) pain intensity and analgesic requirement. Ketamine administered locally during tonsillectomy, decreased PACU and early (6-24 h) pain intensity and PACU analgesic requirements. Used as an adjuvant for caudal analgesia, ketamine increased the duration of sensory block and PACU analgesic requirement without impacting PACU pain intensity. Ketamine failed to exhibit a postoperative opioid-sparing effect.

CONCLUSIONS

This meta-analysis found that administration of ketamine was associated with decreased PACU postoperative pain intensity and nonopioid analgesic requirement. However, ketamine failed to exhibit a postoperative opioid-sparing effect.

Tips and traps analyzing pediatric PK data

Pharmacokinetic (PK) and pharmacodynamic (PD) modeling has elucidated aspects of developmental pharmacology of value to the anesthetic community. The increasing sophistication of modeling techniques is associated with pitfalls that may not be readily apparent to readers or investigators. While size and age are considered primary covariates for PK models, the impact of birth on clearance maturation is poorly documented, dose in obese children is poorly investigated, pharmacologic implications of physiologic changes poorly portrayed, disease progression on drug response poorly depicted and the impact of metabolites on effect poorly illustrated. This review identifies some of these pitfalls and suggests ideas to circumvent or investigate these hazards.

The evolution of ketamine applications in children

Ketamine has found many applications in pediatric anesthetic practice. Insights into the mechanism of action and the pharmacokinetics and pharmacodynamics of its isomers have led to a re-evaluation of this drug, expanding the range of applications in children. Ketamine is a remarkably versatile drug that can be administered through almost any route. It can also be used for different purposes. The aim of this review is to look at the possible applications of this drug in children.

Overview of total intravenous anesthesia in children

Total intravenous anesthesia (TIVA) can be defined as a technique, in which general anesthesia is induced and maintained using purely i.v. agents. TIVA has become more popular and possible in recent times because of the pharmacokinetic (PK) and pharmacodynamic properties of propofol and the availability of short-acting synthetic opioids. Also, new concepts in PK modeling and advances in computer technology have allowed the development of sophisticated delivery systems, which make control of anesthesia given by the i.v. route as straightforward and user friendly as conventional, inhalational techniques. Monitoring of depth of anesthesia is being validated for these techniques, and in the future, measurements of expired propofol may be possible to guide administration. TIVA is being used increasingly in children.

Ketamine inhibits maturation of bone marrow-derived dendritic cells and priming of the Th1-type immune response

BACKGROUND

Dendritic cells (DCs) play a key role as antigen-presenting cells and growing evidence suggests that DCs influence T-cell activation and regulate the polarity of the immune response. Ketamine has been reported to have immunomodulatory properties that affect immune cells, including macrophages and natural killer cells. However, the effect of ketamine on DCs has not been characterized. We examined the immunomodulation of DCs by ketamine.

METHODS

We used bone marrow-derived DCs induced by granulocyte-monocyte-colony stimulating factor and interleukin (IL)-4 from bone marrow and analyzed the expression of costimulatory molecules (CD40, CD80, and CD86), major histocompatibility complex class II molecules, and secretion of IL-12p40. Furthermore, we evaluated the immune response in mixed cell cultures of DCs and T cells and the contact hypersensitivity response in a whole animal.

RESULTS

Ketamine suppressed the expression of CD40, CD80, and major histocompatibility complex class II molecules in DCs. DCs treated with ketamine also secreted less IL-12p40 and displayed greater endocytosis. In mixed cell cultures with CD4+ T cells and DCs, ketamine-treated DCs showed less propensity to stimulate the proliferation of CD4+ T cells and the secretion of interferon from CD4+ T cells. Furthermore, ketamine-treated DCs impaired the induction of a cell-mediated immune response.

CONCLUSION

Our findings suggest that ketamine inhibits the functional maturation of DCs and interferes with DC induction of Th1 immunity in the whole animal. These novel findings provide new insight into the immunopharmacological role of ketamine.