Transient Reductions in Postoperative Pain and Anxiety with the Use of Virtual Reality in Children.

OBJECTIVE: Virtual reality is a promising method to manage pain. Distraction-based virtual reality (VR-D) is thought to reduce pain by redirecting attention. Although VR-D can reduce pain associated with acutely painful procedures, it is unclear whether VR-D can reduce pain after surgery. We assessed the ability of a single VR-D session to decrease postoperative pain and anxiety and explored whether pain catastrophizing and anxiety sensitivity influenced these outcomes in children after surgery. DESIGN: Single-center, prospective, pilot study. SETTING: Cincinnati Children's Hospital Medical Center (CCHMC). SUBJECTS: Fifty children (7-21 years of age) with postoperative pain followed by the Acute Pain Service. METHODS: Patients received one VR-D session after surgery. Before the session, patients completed pain catastrophizing (Pain Catastrophizing Scale for Children) and anxiety sensitivity (Child Anxiety Sensitivity Index) questionnaires. The primary outcome consisted of changes in pain intensity after VR-D (immediately, 15 minutes, and 30 minutes). Secondary outcomes included changes in pain unpleasantness and anxiety. RESULTS: VR-D use was associated with a decrease in pain intensity immediately and 15 minutes after VR-D. Reductions in pain unpleasantness were observed up to 30 minutes after VR-D. VR-D was also associated with a reduction in anxiety immediately and at 15 minutes. Although patients with higher pain catastrophizing had higher baseline pain intensity and unpleasantness, they did not show larger pain reductions after VR-D than those with lower pain catastrophizing. CONCLUSIONS: VR-D may be beneficial in transiently reducing pain intensity, unpleasantness, and anxiety in children with postoperative pain. This study informs the design of a larger, randomized, controlled study assessing VR-D for acute postoperative pain and anxiety management.

Guided Relaxation-Based Virtual Reality for Acute Postoperative Pain and Anxiety in a Pediatric Population: Pilot Observational Study.

BACKGROUND: Distraction-based therapies, such as virtual reality (VR), have been used to reduce pain during acutely painful procedures. However, distraction alone cannot produce prolonged pain reduction to manage sustained postoperative pain. Therefore, the integration of VR with other pain-reducing therapies, like guided relaxation, may enhance its clinical impact. OBJECTIVE: The goal of this pilot study was to assess the impact of a single guided relaxation-based VR (VR-GR) session on postoperative pain and anxiety reduction in children. We also explored the influence of pain catastrophizing and anxiety sensitivity on this association. METHODS: A total of 51 children and adolescents (7-21 years) with postoperative pain and followed by the Acute Pain Service at Cincinnati Children's Hospital were recruited over an 8-month period to undergo a single VR-GR session. Prior to VR, the patients completed 2 questionnaires: Pain Catastrophizing Scale for Children (PCS-C) and the Child Anxiety Sensitivity Index (CASI). The primary outcome was a change in pain intensity following the VR-GR session (immediately, 15 minutes, and 30 minutes). The secondary outcomes included changes in pain unpleasantness and anxiety. RESULTS: The VR-GR decreased pain intensity immediately (P<.001) and at 30 minutes (P=.04) after the VR session, but not at 15 minutes (P=.16) postsession. Reductions in pain unpleasantness were observed at all time intervals (P<.001 at all intervals). Anxiety was reduced immediately (P=.02) but not at 15 minutes (P=.08) or 30 minutes (P=.30) following VR-GR. Patients with higher CASI scores reported greater reductions in pain intensity (P=.04) and unpleasantness (P=.01) following VR-GR. Pain catastrophizing was not associated with changes in pain and anxiety. CONCLUSIONS: A single, short VR-GR session showed transient reductions in pain intensity, pain unpleasantness, and anxiety in children and adolescents with acute postoperative pain. The results call for a future randomized controlled trial to assess the efficacy of VR-GR. TRIAL REGISTRATION: ClinicalTrials.gov NCT04556747; https://clinicaltrials.gov/ct2/show/NCT04556747.

Hydromorphone population pharmacokinetics in pediatric surgical patients.

BACKGROUND: Hydromorphone is an opioid agonist used for pediatric analgesia. Due to lack of data, pediatric dosing (based on adult pharmacokinetic models) is not optimal. AIM: This study characterizes hydromorphone population pharmacokinetics in pediatric surgical patients. METHODS: In this prospective observational study, 34 children (4-18 years, bodyweight 23-89.6 kg) received multiple intravenous hydromorphone boluses followed by postoperative hydromorphone patient-controlled analgesia. Arterial blood samples were collected before and at 3, 10, 30, and 90 (and few samples at 1350) minutes after the first dose. Hydromorphone concentrations were measured by validated LC-MS/MS assay. Nonlinear mixed-effects modeling was used for pharmacokinetic model development. The final population pharmacokinetic model was evaluated by visual predictive check and bootstrap analysis. Monte Carlo simulations based on the final pharmacokinetic model determined optimal patient-controlled analgesia parameters to achieve a target of 20 ng/mL (as the median effective analgesic concentration), using minimum effective analgesic concentration of 4 ng/mL as a proxy for patient-controlled analgesia dose demand, and not exceeding the defined safe upper threshold of 40 ng/mL. RESULTS: Hydromorphone pharmacokinetic profiles were adequately described by a two-compartmental model with first-order elimination. Bodyweight was found to be a significant covariate for hydromorphone clearance. Allometrically scaledpharmacokinetic parameter estimates (per 70 kg), systemic clearance (0.748 L/min), volume of distribution (33 L), peripheral clearance (1.57 L/min), and peripheral volume of distribution (146 L) were similar to reported adult parameter estimates. Sex, race, age, and type of surgery were not identified as significant covariates. To identify optimal patient-controlled analgesia dosing parameters, we simulated several initial loading doses, demand doses, and lockout intervals. Our simulations support an initial patient-controlled analgesia loading dose of 15 µg/kg followed by a demand dose of 6 µg/kg with lockout intervals of 20 minutes. CONCLUSIONS: After intravenous hydromorphone, plasma pharmacokinetic profiles in children undergoing different surgeries were well described by a two-compartment population allometric pharmacokinetic model using bodyweight as the size descriptor. Model informed simulations identified patient-controlled analgesia parameters to inform initial settings, with adjustments as needed based on observed individual effects.

Cost-effectiveness of intravenous acetaminophen and ketorolac in adolescents undergoing idiopathic scoliosis surgery.

BACKGROUND: Enhanced recovery after surgery protocols increasingly use multimodal analgesia after major surgeries with intravenous acetaminophen and ketorolac, despite no documented cost-effectiveness of these strategies. AIMS: The goal of this prospective cohort study was to model cost-effectiveness of adding acetaminophen or acetaminophen + ketorolac to opioids for postoperative outcomes in children having scoliosis surgery. METHODS: Of 106 postsurgical children, 36 received only opioids, 26 received intravenous acetaminophen, and 44 received acetaminophen + ketorolac as analgesia adjuncts. Costs were calculated in 2015 US $. Decision analytic model was constructed with Decision Maker® software. Base-case and sensitivity analyses were performed with effectiveness defined as avoidance of opioid adverse effects. RESULTS: The groups were comparable demographically. Compared with opioids-only strategy, subjects in the intravenous acetaminophen + ketorolac strategy consumed less opioids (P = .002; difference in mean morphine consumption on postoperative days 1 and 2 was -0.44 mg/kg (95% CI -0.72 to -0.16); tolerated meals earlier (P < .001; RR 0.250 (0.112-0.556)) and had less constipation (P < .001; RR 0.226 (0.094-0.546)). Base-case analysis showed that of the 3 strategies, use of opioids alone is both most costly and least effective, opioids + intravenous acetaminophen is intermediate in both cost and effectiveness; and opioids + intravenous acetaminophen and ketorolac is the least expensive and most effective strategy. The addition of intravenous acetaminophen with or without ketorolac to an opioid-only strategy saves $510-$947 per patient undergoing spine surgery and decreases opioid side effects. CONCLUSION: Intravenous acetaminophen with or without ketorolac reduced opioid consumption, opioid-related adverse effects, length of stay, and thereby cost of care following idiopathic scoliosis in adolescents compared with opioids-alone postoperative analgesia strategy.

Pediatric Pain Screening Tool: A Simple 9-Item Questionnaire Predicts Functional and Chronic Postsurgical Pain Outcomes After Major Musculoskeletal Surgeries.

Reliable, clinic-friendly screening for Chronic postsurgical pain (CPSP) risk is unavailable. Within a prospective, observational study, we evaluated Pediatric Pain Screening Tool (PPST), a concise 9-item questionnaire, as a preoperative screening tool to identify those at higher risk for CPSP (Numerical Rating Scale > 3/10 beyond 3 months post-surgery) and poor function (disability/Functional Disability Inventory [FDI]/quality of life/ Pediatric Quality of Life) after spine fusion and Nuss procedures. Incidence of CPSP was 34.86% (38/109). We confirmed PPST scale stability, test re-test reliability (ICC = 0.68; P< .001); PPST measures were positively correlated with known CPSP risk factors (P< .001) preoperative pain (Pearson or Spearman Correlation Coefficient [SCC]:0.672), Child anxiety sensitivity index (SCC:0.357), Patient Related Outcome Measures Information System pain interference (SCC:0.569), Patient Related Outcome Measures Information System depression (SCC:0.501), Pediatric Quality of Life (SCC:-0.460) and insomnia severity index (SCC0.567). Preoperative PPST and PPST physical sub-scores (median(IQR) were higher in CPSP (2[0.5,4], 1[0,2]) compared to non-CPSP (1[0,3], 0[0,1.5]) groups (P= .026, P= .029) respectively. PPST scores/sub-scores positively correlated with higher FDI at 6 months but only PPST total and PPST psychosocial subscore correlated with higher FDI at 12 months. Based on ROC, optimal PPST cutoff for CPSP was 2 (63.9% sensitivity, 64.7% specificity). CPSP risk was high (48.94% risk) if PPST ≥ 2 (n = 47) and medium (22.81%) if PPST < 2 (n = 57) after spine/pectus surgery. General and risk-strata specific, targeted psychosocial non-pharmacological interventions, need to be studied. Findings need validation in diverse, larger cohorts. CLINICALTRIALS.GOV IDENTIFIER: NCT02998138. PERSPECTIVE: The article supports Pediatric Pain Screening Tool, a simple 9-item questionnaire, as a preoperative screening tool for CPSP and function 6-12 months after spine/pectus surgeries. PPST measures correlate with known risk factors for CPSP. Risk stratification and targeted preventive interventions in high-risk subjects are proposed.

Systems Biology Guided Gene Enrichment Approaches Improve Prediction of Chronic Post-surgical Pain After Spine Fusion.

OBJECTIVES: Incorporation of genetic factors in psychosocial/perioperative models for predicting chronic postsurgical pain (CPSP) is key for personalization of analgesia. However, single variant associations with CPSP have small effect sizes, making polygenic risk assessment important. Unfortunately, pediatric CPSP studies are not sufficiently powered for unbiased genome wide association (GWAS). We previously leveraged systems biology to identify candidate genes associated with CPSP. The goal of this study was to use systems biology prioritized gene enrichment to generate polygenic risk scores (PRS) for improved prediction of CPSP in a prospectively enrolled clinical cohort. METHODS: In a prospectively recruited cohort of 171 adolescents (14.5 ± 1.8 years, 75.4% female) undergoing spine fusion, we collected data about anesthesia/surgical factors, childhood anxiety sensitivity (CASI), acute pain/opioid use, pain outcomes 6-12 months post-surgery and blood (for DNA extraction/genotyping). We previously prioritized candidate genes using computational approaches based on similarity for functional annotations with a literature-derived "training set." In this study, we tested ranked deciles of 1336 prioritized genes for increased representation of variants associated with CPSP, compared to 10,000 randomly selected control sets. Penalized regression (LASSO) was used to select final variants from enriched variant sets for calculation of PRS. PRS incorporated regression models were compared with previously published non-genetic models for predictive accuracy. RESULTS: Incidence of CPSP in the prospective cohort was 40.4%. 33,104 case and 252,590 control variants were included for association analyses. The smallest gene set enriched for CPSP had 80/1010 variants associated with CPSP (p < 0.05), significantly higher than in 10,000 randomly selected control sets (p = 0.0004). LASSO selected 20 variants for calculating weighted PRS. Model adjusted for covariates including PRS had AUROC of 0.96 (95% CI: 0.92-0.99) for CPSP prediction, compared to 0.70 (95% CI: 0.59-0.82) for non-genetic model (p < 0.001). Odds ratios and positive regression coefficients for the final model were internally validated using bootstrapping: PRS [OR 1.98 (95% CI: 1.21-3.22); ß 0.68 (95% CI: 0.19-0.74)] and CASI [OR 1.33 (95% CI: 1.03-1.72); ß 0.29 (0.03-0.38)]. DISCUSSION: Systems biology guided PRS improved predictive accuracy of CPSP risk in a pediatric cohort. They have potential to serve as biomarkers to guide risk stratification and tailored prevention. Findings highlight systems biology approaches for deriving PRS for phenotypes in cohorts less amenable to large scale GWAS.

Methylation quantitative trait locus analysis of chronic postsurgical pain uncovers epigenetic mediators of genetic risk.

Background: Overlap of pathways enriched by single nucleotide polymorphisms and DNA-methylation underlying chronic postsurgical pain (CPSP), prompted pilot study of CPSP-associated methylation quantitative trait loci (meQTL). Materials & methods: Children undergoing spine-fusion were recruited prospectively. Logistic-regression for genome- and epigenome-wide CPSP association and DNA-methylation-single nucleotide polymorphism association/mediation analyses to identify meQTLs were followed by functional genomics analyses. Results: CPSP (n = 20/58) and non-CPSP groups differed in pain-measures. Of 2753 meQTLs, DNA-methylation at 127 cytosine-guanine dinucleotides mediated association of 470 meQTLs with CPSP (p < 0.05). At PARK16 locus, CPSP risk meQTLs were associated with decreased DNA-methylation at RAB7L1 and increased DNA-methylation at PM20D1. Corresponding RAB7L1/PM20D1 blood eQTLs (GTEx) and cytosine-guanine dinucleotide-loci enrichment for histone marks, transcription factor binding sites and ATAC-seq peaks suggest altered transcription factor-binding. Conclusion: CPSP-associated meQTLs indicate epigenetic mechanisms mediate genetic risk. Clinical trial registration: NCT01839461, NCT01731873 (ClinicalTrials.gov).

Guided relaxation-based virtual reality versus distraction-based virtual reality or passive control for postoperative pain management in children and adolescents undergoing Nuss repair of pectus excavatum: protocol for a prospective, randomised, controlled trial (FOREVR Peds trial).

INTRODUCTION: Virtual reality (VR) offers an innovative method to deliver non-pharmacological pain management. Distraction-based VR (VR-D) using immersive games to redirect attention has shown short-term pain reductions in various settings. To create lasting pain reduction, VR-based strategies must go beyond distraction. Guided relaxation-based VR (VR-GR) integrates pain-relieving mind-body based guided relaxation with VR, a novel therapy delivery mechanism. The primary aim of this study is to assess the impact of daily VR-GR, VR-D and 360 video (passive control) on pain intensity. We will also assess the impact of these interventions on pain unpleasantness, anxiety and opioid and benzodiazepine consumption. The secondary aim of this study will assess the impact of psychological factors (anxiety sensitivity and pain catastrophising) on pain following VR. METHODS AND ANALYSIS: This is a single centre, prospective, randomised, clinical trial. Ninety children/adolescents, aged 8-18 years, presenting for Nuss repair of pectus excavatum will be randomised to 1 of 3 study arms (VR-GR, VR-D and 360 video). Patients will use the Starlight Xperience (Google Daydream) VR suite for 10 min. Patients randomised to VR-GR (n=30) will engage in guided relaxation/mindfulness with the Aurora application. Patients randomised to VR-D (n=30) will play 1 of 3 distraction-based games, and those randomised to the 360 video (n=30) will watch the Aurora application without audio instructions or sound. Primary outcome is pain intensity. Secondary outcomes include pain unpleasantness, anxiety and opioid and benzodiazepine consumption. ETHICS AND DISSEMINATION: This study follows Standard Protocol Items: Recommendations for Interventional Trials guidelines. The protocol was approved by the Cincinnati Children's Hospital Medical Center's institutional review board. Patient recruitment began in July 2020. Written informed consent will be obtained for all participants. All information acquired will be disseminated via scientific meetings and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04351776.

Enrichment of Genomic Pathways Based on Differential DNA Methylation Associated With Chronic Postsurgical Pain and Anxiety in Children: A Prospective, Pilot Study.

We have reported child anxiety sensitivity (Child Anxiety Sensitivity Index [CASI]) predicts chronic postsurgical pain (CPSP). Herein, we evaluated DNA methylation profiles to understand the gene-environment interactions underlying CPSP and CASI, to identify shared, enriched, genomic pathways. In 73 prospectively recruited adolescents undergoing spine fusion, preoperative CASI and pain data over 12 months after surgery were collected. DNA from the peripheral blood of evaluable subjects with (n = 16) and without CPSP (n = 40) were analyzed using MethylationEPIC arrays. We identified 637 and 2,445 differentially DNA methylated positions (DMPs) associated with CPSP and CASI, respectively (P ≤ .05). Ingenuity pathway analysis of 39 genes with DMPs for both CPSP and CASI revealed enrichment of several canonical pathways, including GABA receptor (P = .00016 for CPSP; P =.0008 for CASI) and dopamine-DARPP32 feedback in cyclic adenosine monophosphate (P = .004 for CPSP and P =.00003 for CASI) signaling. Gene-gene interaction network enrichment analysis revealed participation of pathways in cell signaling, molecular transport, metabolism, and neurologic diseases (P < 10-8). Bioinformatic approaches to identify histone marks and transcription factor (TF) binding events underlying DMPs, showed their location in active regulatory regions in pain pathway relevant brain cells. Using Enrichr/Pinet enrichment and Library of Integrated Network-Based Cellular Signatures knockdown signatures, we identified TFs regulating genes with DMPs in association with CPSP and CASI. In conclusion, we identified epigenetically enriched pathways associated with CPSP and anxiety sensitivity in children undergoing surgery. Our findings support GABA hypofunction and the roles of the dopamine-DARPP32 pathway in emotion/reward and pain. This pilot study provides new epigenetic insights into the pathophysiology of CPSP and a basis for future studies in biomarker development and targetable interventions. PERSPECTIVE: Differential DNA methylation in regulatory genomic regions enriching shared neural pathways were associated with CPSP and CASI in adolescents undergoing spine surgery. Our findings support GABA hypofunction and the roles of the dopamine-DARPP32 pathway in emotion/reward contributing to behavioral maintenance of pain 10 to 12 months after surgery.

DNA methylation at the mu-1 opioid receptor gene (OPRM1) promoter predicts preoperative, acute, and chronic postsurgical pain after spine fusion.

INTRODUCTION: The perioperative pain experience shows great interindividual variability and is difficult to predict. The mu-1 opioid receptor gene (OPRM1) is known to play an important role in opioid-pain pathways. Since deoxyribonucleic acid (DNA) methylation is a potent repressor of gene expression, DNA methylation was evaluated at the OPRM1 promoter, as a predictor of preoperative, acute, and chronic postsurgical pain (CPSP). METHODS: A prospective observational cohort study was conducted in 133 adolescents with idiopathic scoliosis undergoing spine fusion under standard protocols. Data regarding pain, opioid consumption, anxiety, and catastrophizing (using validated questionnaires) were collected before and 2-3 months postsurgery. Outcomes evaluated were preoperative pain, acute postoperative pain (area under curve [AUC] for pain scores over 48 hours), and CPSP (numerical rating scale >3/10 at 2-3 months postsurgery). Blood samples collected preoperatively were analyzed for DNA methylation by pyrosequencing of 22 CpG sites at the OPRM1 gene promoter. The association of each pain outcome with the methylation percentage of each CpG site was assessed using multivariable regression, adjusting for significant (P<0.05) nongenetic variables. RESULTS: Majority (83%) of the patients reported no pain preoperatively, while CPSP occurred in 36% of the subjects (44/121). Regression on dichotomized preoperative pain outcome showed association with methylation at six CpG sites (1, 3, 4, 9, 11, and 17) (P<0.05). Methylation at CpG sites 4, 17, and 18 was associated with higher AUC after adjusting for opioid consumption and preoperative pain score (P<0.05). After adjusting for postoperative opioid consumption and preoperative pain score, methylation at CpG sites 13 and 22 was associated with CPSP (P<0.05). DISCUSSION: Novel CPSP biomarkers were identified in an active regulatory region of the OPRM1 gene that binds multiple transcription factors. Inhibition of binding by DNA methylation potentially decreases the OPRM1 gene expression, leading to a decreased response to endogenous and exogenous opioids, and an increased pain experience.