Prospective evaluation of acute neurological events after paediatric cardiac surgery.

OBJECTIVES: Children with CHD are at heightened risk of neurodevelopmental problems; however, the contribution of acute neurological events specifically linked to the perioperative period is unclear. AIMS: This secondary analysis aimed to quantify the incidence of acute neurological events in a UK paediatric cardiac surgery population, identify risk factors, and assess how acute neurological events impacted the early post-operative pathway. METHODS: Post-operative data were collected prospectively on 3090 consecutive cardiac surgeries between October 2015 and June 2017 in 5 centres. The primary outcome of analysis was acute neurological event, with secondary outcomes of 6-month survival and post-operative length of stay. Patient and procedure-related variables were described, and risk factors were statistically explored with logistic regression. RESULTS: Incidence of acute neurological events after paediatric cardiac surgery in our population occurred in 66 of 3090 (2.1%) consecutive cardiac operations. 52 events occurred with other morbidities including renal failure (21), re-operation (20), cardiac arrest (20), and extracorporeal life support (18). Independent risk factors for occurrence of acute neurological events were CHD complexity 1.9 (1.1-3.2), p = 0.025, longer operation times 2.7 (1.6-4.8), p < 0.0001, and urgent surgery 3.4 (1.8-6.3), p < 0.0001. Unadjusted comparison found that acute neurological event was linked to prolonged post-operative hospital stay (median 35 versus 9 days) and poorer 6-month survival (OR 13.0, 95% CI 7.2-23.8). CONCLUSION: Ascertainment of acute neurological events relates to local measurement policies and was rare in our population. The occurrence of acute neurological events remains a suitable post-operative metric to follow for quality assurance purposes.

The Impact of Morbidities Following Pediatric Cardiac Surgery on Family Functioning and Parent Quality of Life.

We previously selected and defined nine important post-operative morbidities linked to paediatric cardiac surgery, and prospectively measured their incidence following 3090 consecutive operations. Our aim was to study the impact of these morbidities on family functioning and parental quality of life over 6 months in a subset of cases. As part of a prospective case matched study in five of the ten children's cardiac centers in the UK, we compared outcomes for parents of children who had a 'single morbidity', 'multiple morbidities', 'extracorporeal life support (ECLS)' or 'no morbidity'. Outcomes were evaluated using the PedsQL Family impact module (FIM) at 6 weeks and 6 months post-surgery. Outcomes were modelled using mixed effects regression, with adjustment for case mix and clustering within centers. We recruited 340 patients with morbidity (60% of eligible patients) and 326 with no morbidity over 21 months. In comparison to the reference group of 'no morbidity', after adjustment for case mix, at 6 weeks parent health-related quality of life (HRQoL) and total FIM sores were lower (worse) only for ECLS (p < 0.005), although a higher proportion of parents in both the ECLS and multi-morbidity groups had low/very low scores (p < .05). At 6 months, parent outcomes had improved for all groups but parent HRQoL and total score for ECLS remained lower than the 'no morbidity' group (p < .05) and a higher proportion of families had low or very low scores in the ECLS (70%) group (p < .01). Post-operative morbidities impact parent HRQoL and aspects of family functioning early after surgery, with this impact lessening by 6 months. Families of children who experience post-operative morbidities should be offered timely psychological support.

The Infant KIdney Dialysis and Utrafiltration (I-KID) Study: A Stepped-Wedge Cluster-Randomized Study in Infants, Comparing Peritoneal Dialysis, Continuous Venovenous Hemofiltration, and Newcastle Infant Dialysis Ultrafiltration System, a Novel Infant Hemodialysis Device.

OBJECTIVES: Renal replacement therapy (RRT) options are limited for small babies because of lack of available technology. We investigated the precision of ultrafiltration, biochemical clearances, clinical efficacy, outcomes, and safety profile for a novel non-Conformité Européenne-marked hemodialysis device for babies under 8 kg, the Newcastle Infant Dialysis Ultrafiltration System (NIDUS), compared with the current options of peritoneal dialysis (PD) or continuous venovenous hemofiltration (CVVH). DESIGN: Nonblinded cluster-randomized cross-sectional stepped-wedge design with four periods, three sequences, and two clusters per sequence. SETTING: Clusters were six U.K. PICUs. PATIENTS: Babies less than 8 kg requiring RRT for fluid overload or biochemical disturbance. INTERVENTIONS: In controls, RRT was delivered by PD or CVVH, and in interventions, NIDUS was used. The primary outcome was precision of ultrafiltration compared with prescription; secondary outcomes included biochemical clearances. MEASUREMENTS AND MAIN RESULTS: At closure, 97 participants were recruited from the six PICUs (62 control and 35 intervention). The primary outcome, obtained from 62 control and 21 intervention patients, showed that ultrafiltration with NIDUS was closer to that prescribed than with control: sd controls, 18.75, intervention, 2.95 (mL/hr); adjusted ratio, 0.13; 95% CI, 0.03-0.71; p = 0.018. Creatinine clearance was smallest and least variable for PD (mean, sd ) = (0.08, 0.03) mL/min/kg, larger for NIDUS (0.46, 0.30), and largest for CVVH (1.20, 0.72). Adverse events were reported in all groups. In this critically ill population with multiple organ failure, mortality was lowest for PD and highest for CVVH, with NIDUS in between. CONCLUSIONS: NIDUS delivers accurate, controllable fluid removal and adequate clearances, indicating that it has important potential alongside other modalities for infant RRT.

The Relationship Between Postoperative Complications and Children's Quality of Life: A Mediation Analysis to Explore the Role of Family Factors.

OBJECTIVES: To explore whether postoperative morbidities after pediatric cardiac surgery affected children's health-related quality of life (HRQOL) at 6 months, through potentially modifiable parental psychological factors. DESIGN: We undertook a mediation analysis, to explore the causal pathway, based on data from a prospective, case-matched cohort study. PATIENTS: Six hundred sixty-six children undergoing cardiac surgery. SETTING: Five centers in the United Kingdom. INTERVENTIONS: No intervention. MEASUREMENTS AND MAIN RESULTS: Cases of morbidity were identified early after pediatric cardiac surgery, and matched controls with no morbidities were identified at discharge. Four mediators were assessed at 6 weeks after surgery, using the PedsQL Family Impact Module (Parent HRQOL and Family Function) and the PHQ-4 (Anxiety and Depression). The study outcome of child HRQOL was assessed at 6 months with the PedsQL. Of 666 children, 408 (65% of those surviving) contributed to the primary outcome. Children who had extracorporeal life support (ECLS) ( n = 11) ( p < 0.05) and multiple morbidities ( n = 62) ( p < 0.01) had worse 6-month HRQOL than those with a single morbidity ( n = 125) or no morbidity ( n = 209). After adjustment for case mix complexity and sociodemographic variables, there were significant indirect effects of parent HRQOL at 6 weeks, on the PedsQL Total Score (ECLS, -5.1 [-8.4 to -1.8]; p = 0.003; multiple morbidities, -2.1 [-3.7 to -0.5]; p = 0.01), PedsQL Physical Score (ECLS, -5.1 [-8.7 to -1.4]; p = 0.007; multiple morbidities, -2.1 [-3.8 to -0.4]; p = 0.016), and PedsQL Psychosocial Score (ECLS: -5.3 [-8.7 to -1.8); p = 0.003; multiple morbidities, -2.2 [-3.9 to -0.5]; p = 0.01). The proportion of the total effect of ECLS and multiple morbidity on the study outcomes mediated through parent HRQOL ranges between 18% and 61%. There was no evidence that the other three mediators had indirect effects on the study outcome. CONCLUSIONS: Parental HRQOL at 6 weeks after surgery contributes to child HRQOL at 6 months, among those with the severest types of morbidity, and as such should be a target for future interventions.

Postoperative morbidities with infant cardiac surgery and toddlers' neurodevelopment.

OBJECTIVE: To evaluate the relationship between morbidities after infant cardiac surgery and neurodevelopment and behaviour at age 2-3 years. DESIGN/SETTING: A prospective cohort follow-up study, in four paediatric cardiac centres. We excluded children with known syndromes. Home-based neurodevelopmental assessments using the Bayley Scales of Infant and Toddler Development 3rd Edition (Bayley-III) were undertaken in 81 children and secondary outcome measures of development and behaviour were completed by parents. A further 41 families completed the secondary outcome measures remotely. RESULTS: Children were grouped as multiple morbidities/extracorporeal life support (ECLS) (n=19), single morbidities (n=36) and no morbidities (n=59). Group comparisons found that children with multiple morbidities/ECLS, compared with no morbidities, had: (a) lower adjusted mean scores for core Bayley-III composites (none reached the level of statistical significance), with mean differences of cognitive -6.1 (95% CI -12.4 to 0.1) p=0.06, language -9.1 (95% CI -18.6 to 0.3) p=0.06 and motor -4.4 (95% CI -12.0 to 3.1) p=25; (b) greater adjusted odds of at least one low or borderline Bayley-III composite result 4.0 (95% CI 1.0 to 16.0) (p=0.05); (c) greater adjusted risk of an abnormal Ages and Stages Questionnaire (ASQ) result 5.3 (95% CI 1.3 to 21.1) (p=0.03) and a borderline ASQ result 4.9 (95% CI 1.0 to 25.0) (p=0.05); and no difference in the risk of an abnormal Strengths and Difficulties Questionnaire result 1.7 (95% CI 0.3 to 10.4) p=0.58. These outcomes were not statistically different between the single morbidity and no morbidity groups. CONCLUSIONS: Children who experience multiple morbidities/ECLS after infant heart surgery are at a greater risk of neurodevelopmental difficulties than their peers who had no complications and should be prioritised for neurodevelopmental follow-up.

In vitro measurements of ultrafiltration precision in hemofiltration and hemodialysis devices used in infants.

BACKGROUND: To determine in vitro whether infant hemofiltration and hemodialysis devices can reliably deliver precise ultrafiltration (UF) control. METHODS: We tested the Prismaflex, Aquarius and NIDUS devices which have different circuit types, by in vitro testing with a bag of saline set up as a dummy patient, and monitoring fluid shifts by precise weighing. We looked for differences between the UF rates set and achieved and between the UF result the device displays to the clinician and the true volumes removed, which may lead to clinical errors. We performed short studies at UF settings of zero and 40 ml/h, and with and without simulating poor withdrawal and return lines, and simulated a 4-h treatment session. RESULTS: The Prismaflex setting vs actual errors and display vs actual errors had wide variances, with SDs of 4.1 and 14.0 ml by 15 min, respectively, at both zero and 40 ml/h UF settings. The Aquarius values were wider at 17.3 and 30.3 ml, respectively. For the NIDUS, the mean UF errors were close to zero, and the variances were 0.17 ml. Stop-alarms induced by an obstructed line produced extra UF errors of up to 0.2 ml. A limitation was that we used crystalloid and not colloid for these tests. CONCLUSIONS: Hemotherapy devices with conventional circuits available in the UK do not regulate UF control sufficiently well to recommend for use in small infants, but the NIDUS volumetrically controlled circuit does. All hemotherapy devices intended for small infants should be tested for UF precision. We were unable to test the CARPEDIEM or Aquadex devices. A higher resolution version of the Graphical abstract is available as Supplementary information.

Prospective evaluation of a novel enteral feeding guideline based on individual gastric emptying times: an improvement project in a pediatric intensive care unit.

BACKGROUND: On a 20-bed, mixed cardiac and general, UK pediatric intensive care unit (PICU), we aimed to determine if a physiologically based enteral feeding guideline for critically ill children, using feed frequency tailored to individual gastric emptying times, resulted in earlier establishment of full feeds (when 100% of fluid allowance (FA) available to be given as intravenous maintenance fluid or feed, defined as free FA [FFA], is given as enteral nutrition [EN]) and an increase in FFA given as EN. METHODS: Four prospective audits (totaling 331 patients and 19,771 hours) were conducted at 1 year before guideline introduction and 1, 5, and 10 years after. Patient feeding data were collected from admission until day 4 or discharge, including reasons why feed was withheld. RESULTS: The median time from admission to establishing full feeds decreased from 18 to 10 hours preguideline and postguideline and was sustained over 10 years. After adjustment for 5 confounders, this represented a reduction in the geometric mean time to full feeds of 30% (2009), 29% (2013), and 48% (2019) compared with 2007 (all P < .01). Nil-per-oral (NPO) hours were categorized as due to modifiable and nonmodifiable factors. Preguideline and postguideline NPO hours from modifiable factors decreased from 21 (2007) to 10 (2009) per 100 audit hours, which was sustained across 10 years (all P < .01). Conversely, NPO hours from nonmodifiable factors ranged from 27 to 36 per 100 audit hours throughout the audits, with no consistent trend over time. Similar inconsistency was shown in the proportion of FFA given as EN: 48% (2007), 71% (2009), 51% (2013), and 64% (2019). Continuous nasogastric and hourly bolus feeds decreased over time; they comprised 66% of feeds in 2007 but only 4%-11% in subsequent periods, being replaced with more 2-6 hour bolus, on-demand, or continuous nasojejunal feeds. CONCLUSION: The guideline was associated with sustained reduction in the time to establishing full feeds and NPO hours due to modifiable factors and more or no less FFA being given as EN.

Factors associated with unplanned reinterventions and their relation to early mortality after pediatric cardiac surgery.

OBJECTIVE: Unplanned reintervention (uRE) is used as an indicator of patient morbidity and quality of care in pediatric cardiac surgery. We investigated associated factors and early mortality after uREs. METHODS: Morbidity data were prospectively collected in 5 UK centers between 2015 and 2017; uRE included surgical cardiac, interventional transcatheter cardiac, permanent pacemaker, and diaphragm plication procedures. Mortality (30-day and 6-month) in uRE/no-uRE patients was reported before and after matching. Predicted 30-day mortality was calculated using the Partial Risk Adjustment in Surgery score. RESULTS: A total of 3090 procedures (2861 patients) were included (median age, 228 days). There were 146 uREs, resulting in an uRE rate of 4.7%. Partial Risk Adjustment in Surgery score, 30-day mortality and 6-month mortality in uRE and no-uRE groups were 2.4% versus 1.3%, 8.9% versus 1%, and 17.1% versus 2.4%, respectively. After matching, mortality at 6 months remained higher in uRE compared with no-uRE (12.2% vs 1.4%; P = .02; 74 pairs). In the uRE group, 21 out of 25 deaths at 6 months occurred when at least 1 additional postoperative complication was present. In multivariable analysis, neonatal age (P = .002), low weight (P = .009), univentricular heart (P < .001), and arterial shunt (P < .001) were associated with increased risk of uRE, but Partial Risk Adjustment in Surgery score was not (only in univariable analysis). CONCLUSIONS: uREs are a relatively frequent complication after pediatric cardiac surgery and are associated with some patient characteristics, but not the Partial Risk Adjustment in Surgery risk score. Early mortality was higher after uRE, independent of preoperative factors, but linked to other postoperative complications.

Morbidities After Cardiac Surgery: Impact on Children's Quality of Life and Parents' Mental Health.

BACKGROUND: Most children now survive cardiac surgery, and the focus of quality improvement initiatives has shifted toward more complex outcome measures. The aim of this investigation was to study the impact of early postoperative morbidities on parent-reported patient quality of life and parental anxiety or depression over 6 months. METHODS: This prospective case-matched cohort study was conducted in 5 UK children's cardiac centers. Measures of impact for patient categories of "single morbidity," "multiple morbidities," and "extracorporeal life support (ECLS)" were compared with "no morbidity." The measures used were the Pediatric Quality of Life Inventory (PedsQL) and the 4-item Patient Health Questionnaire (PHQ-4) at 6 weeks and 6 months postoperatively. The study modeled the outcomes using mixed effects regression, adjusting for case mix and clustering within centers. RESULTS: The study included 666 patients who underwent operation at a median age of 81 days (interquartile range, 10 to 325 days). At 6-week follow-up, significant adjusted differences to the reference group with no morbidity were found for total PedsQL scores, which were lower in patients with ECLS (P = .01), multiple morbidities (P < .001), and a single morbidity (P = .04), as well as the proportion of parents with anxiety and depression, which were higher in the group with multiple morbidities (P = .04 and P = .01, respectively). At 6 months, measures had improved in all morbidity groups. The only significant adjusted difference in the reference group was for physical PedsQL scores in ECLS (P = .04) and multiple morbidities (P < .01). CONCLUSIONS: Patient and parent well-being are strongly influenced by postoperative morbidities early after surgery, with improvement by 6 months. Family psychological support and holistic rehabilitation are vital for children who experience postoperative morbidities.

Peripheral immunophenotypes in children with multisystem inflammatory syndrome associated with SARS-CoV-2 infection.

Recent reports highlight a new clinical syndrome in children related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1-multisystem inflammatory syndrome in children (MIS-C)-which comprises multiorgan dysfunction and systemic inflammation2-13. We performed peripheral leukocyte phenotyping in 25 children with MIS-C, in the acute (n = 23; worst illness within 72 h of admission), resolution (n = 14; clinical improvement) and convalescent (n = 10; first outpatient visit) phases of the illness and used samples from seven age-matched healthy controls for comparisons. Among the MIS-C cohort, 17 (68%) children were SARS-CoV-2 seropositive, suggesting previous SARS-CoV-2 infections14,15, and these children had more severe disease. In the acute phase of MIS-C, we observed high levels of interleukin-1ß (IL-1ß), IL-6, IL-8, IL-10, IL-17, interferon-γ and differential T and B cell subset lymphopenia. High CD64 expression on neutrophils and monocytes, and high HLA-DR expression on γδ and CD4+CCR7+ T cells in the acute phase, suggested that these immune cell populations were activated. Antigen-presenting cells had low HLA-DR and CD86 expression, potentially indicative of impaired antigen presentation. These features normalized over the resolution and convalescence phases. Overall, MIS-C presents as an immunopathogenic illness1 and appears distinct from Kawasaki disease.

Pre-exposure of adolescent mice to morphine results in stronger sensitization and reinstatement of conditioned place preference than pre-exposure to hydrocodone.

BACKGROUND: Opioids are commonly prescribed to treat moderate-to-severe pain. However, their use can trigger the development of opioid use disorder. A major problem in treating opioid use disorder remains the high rate of relapse. AIM: The purpose of this study was to determine whether there are differences among opioids in their ability to trigger relapse after pre-exposure during adolescence. METHODS: On postnatal day 33, mice were examined for the acute locomotor response to saline, morphine, or hydrocodone (5 mg/kg). They were administered with the corresponding opioid or saline during postnatal days 34-38 (20 mg/kg) and 40-44 (40 mg/kg). On postnatal day 45, they were recorded for the development of locomotor sensitization (5 mg/kg). Starting on postnatal day 55, mice were examined for the acquisition (1, 5, 10, 20, and 40 mg/kg), extinction, and drug-induced reinstatement (1, 2.5, and 5 mg/kg) of conditioned place preference. RESULTS: There were no significant differences in the acute locomotor response to morphine and hydrocodone. Morphine induced significantly stronger locomotor sensitization as compared to hydrocodone. Pre-exposure to morphine, but not hydrocodone, sensitized the acquisition of conditioned place preference. There were no significant differences in extinction rates. Mice pre-exposed to morphine reinstate conditioned place preference after priming with a 1 mg/kg dose. In contrast, higher priming doses were required for reinstatement in all other experimental groups. CONCLUSIONS: Adolescent mice administered with morphine develop greater sensitization to its effects and subsequently reinstate conditioned place preference more readily than mice administered with hydrocodone. This suggests higher risk for relapse after pre-exposure to morphine during adolescence as compared to hydrocodone.

Response to opioids is dependent on sociability levels.

Social environment influences the trajectory of developing opioid use disorder (OUD). Thus, the present study tested the hypothesis that sociability levels will affect the responses to opioids. Mice were tested for their baseline sociability, anxiety levels, pain sensitivities, and their acute locomotor response to 5 mg/kg opioids. Then, they were administered repeatedly with saline, hydrocodone, or morphine (20 mg/kg for 5 days, and then 40 mg/kg for 5 days). Subsequently, they were examined for the expression of locomotor sensitization and retested for the effects of opioids on their sociability, anxiety levels, and pain sensitivity. On the basis of their baseline sociability level, mice were divided into socially avoiding and socially exploring. Socially avoiding and socially exploring mice did not differ in their baseline weight and anxiety sensitivities. Socially avoiding mice had slightly higher baseline heat sensitivity than those in socially exploring mice. Repeated administration of opioids had differential effects in socially avoiding and socially exploring mice. In both social groups, repeated morphine administration had overall stronger effects compared with hydrocodone. Morphine-treated socially exploring mice developed greater locomotor sensitization than those in morphine-treated socially avoiding mice. Morphine-treated socially avoiding mice, but not socially exploring mice, spent more time in the center zone of the open-field test and in the light zone of light/dark boxes, and developed heat hyperalgesia. This study suggests that socially exploring animals are more sensitive to the sensitizing effects of opioids. In contrast, opioids have greater effects on the stress and pain systems of socially avoiding animals. Thus, the underlying mechanisms for developing OUD might differ in individuals with various sociability levels.

Permissive versus restrictive temperature thresholds in critically ill children with fever and infection: a multicentre randomized clinical pilot trial.

BACKGROUND: Fever improves pathogen control at a significant metabolic cost. No randomized clinical trials (RCT) have compared fever treatment thresholds in critically ill children. We performed a pilot RCT to determine whether a definitive trial of a permissive approach to fever in comparison to current restrictive practice is feasible in critically ill children with suspected infection. METHODS: An open, parallel-group pilot RCT with embedded mixed methods perspectives study in four UK paediatric intensive care units (PICUs) and associated retrieval services. Participants were emergency PICU admissions aged > 28 days to < 16 years receiving respiratory support and supplemental oxygen. Subjects were randomly assigned to permissive (antipyretic interventions only at ≥ 39.5 °C) or restrictive groups (antipyretic interventions at ≥ 37.5 °C) whilst on respiratory support. Parents were invited to complete a questionnaire or take part in an interview. Focus groups were conducted with staff at each unit. Outcomes were measures of feasibility: recruitment rate, protocol adherence and acceptability, between group separation of temperature and safety. RESULTS: One hundred thirty-eight children met eligibility criteria of whom 100 (72%) were randomized (11.1 patients per month per site) without prior consent (RWPC). Consent to continue in the trial was obtained in 87 cases (87%). The mean maximum temperature (95% confidence interval) over the first 48 h was 38.4 °C (38.2-38.6) in the restrictive group and 38.8 °C (38.6-39.1) in the permissive group, a mean difference of 0.5 °C (0.2-0.8). Protocol deviations were observed in 6.8% (99/1438) of 6-h time periods and largely related to patient comfort in the recovery phase. Length of stay, duration of organ support and mortality were similar between groups. No pre-specified serious adverse events occurred. Staff (n = 48) and parents (n = 60) were supportive of the trial, including RWPC. Suggestions were made to only include invasively ventilated children for the duration of intubation. CONCLUSION: Uncertainty around the optimal fever threshold for antipyretic intervention is relevant to many emergency PICU admissions. A more permissive approach was associated with a modest increase in mean maximum temperature. A definitive trial should focus on the most seriously ill cases in whom antipyretics are rarely used for their analgesic effects alone. TRIAL REGISTRATION: ISRCTN16022198 . Registered on 14 August 2017.

Different temperature thresholds for antipyretic intervention in critically ill children with fever due to infection: the FEVER feasibility RCT.

BACKGROUND: Fever accelerates host immune system control of pathogens but at a high metabolic cost. The optimal approach to fever management and the optimal temperature thresholds used for treatment in critically ill children are unknown. OBJECTIVES: To determine the feasibility of conducting a definitive randomised controlled trial (RCT) to evaluate the clinical effectiveness and cost-effectiveness of different temperature thresholds for antipyretic management. DESIGN: A mixed-methods feasibility study comprising three linked studies - (1) a qualitative study exploring parent and clinician views, (2) an observational study of the epidemiology of fever in children with infection in paediatric intensive care units (PICUs) and (3) a pilot RCT with an integrated-perspectives study. SETTING: Participants were recruited from (1) four hospitals in England via social media (for the FEVER qualitative study), (2) 22 PICUs in the UK (for the FEVER observational study) and (3) four PICUs in England (for the FEVER pilot RCT). PARTICIPANTS: (1) Parents of children with relevant experience were recruited to the FEVER qualitative study, (2) patients who were unplanned admissions to PICUs were recruited to the FEVER observational study and (3) children admitted with infection requiring mechanical ventilation were recruited to the FEVER pilot RCT. Parents of children and clinicians involved in the pilot RCT. INTERVENTIONS: The FEVER qualitative study and the FEVER observational study had no interventions. In the FEVER pilot RCT, children were randomly allocated (1 : 1) using research without prior consent (RWPC) to permissive (39.5 °C) or restrictive (37.5 °C) temperature thresholds for antipyretics during their PICU stay while mechanically ventilated. MAIN OUTCOME MEASURES: (1) The acceptability of FEVER, RWPC and potential outcomes (in the FEVER qualitative study), (2) the size of the potentially eligible population and the temperature thresholds used (in the FEVER observational study) and (3) recruitment and retention rates, protocol adherence and separation between groups and distribution of potential outcomes (in the FEVER pilot RCT). RESULTS: In the FEVER qualitative study, 25 parents were interviewed and 56 clinicians took part in focus groups. Both the parents and the clinicians found the study acceptable. Clinicians raised concerns regarding temperature thresholds and not using paracetamol for pain/discomfort. In the FEVER observational study, 1853 children with unplanned admissions and infection were admitted to 22 PICUs between March and August 2017. The recruitment rate was 10.9 per site per month. The majority of critically ill children with a maximum temperature of > 37.5 °C received antipyretics. In the FEVER pilot RCT, 100 eligible patients were randomised between September and December 2017 at a recruitment rate of 11.1 per site per month. Consent was provided for 49 out of 51 participants in the restrictive temperature group, but only for 38 out of 49 participants in the permissive temperature group. A separation of 0.5 °C (95% confidence interval 0.2 °C to 0.8 °C) between groups was achieved. A high completeness of outcome measures was achieved. Sixty parents of 57 children took part in interviews and/or completed questionnaires and 98 clinicians took part in focus groups or completed a survey. Parents and clinicians found the pilot RCT and RWPC acceptable. Concerns about children being in pain/discomfort were cited as reasons for withdrawal and non-consent by parents and non-adherence to the protocol by clinicians. LIMITATIONS: Different recruitment periods for observational and pilot studies may not fully reflect the population that is eligible for a definitive RCT. CONCLUSIONS: The results identified barriers to delivering the definitive FEVER RCT, including acceptability of the permissive temperature threshold. The findings also provided insight into how these barriers may be overcome, such as by limiting the patient inclusion criteria to invasive ventilation only and by improved site training. A definitive FEVER RCT using a modified protocol should be conducted, but further work is required to agree important outcome measures for clinical trials among critically ill children. TRIAL REGISTRATION: The FEVER observational study is registered as NCT03028818 and the FEVER pilot RCT is registered as Current Controlled Trials ISRCTN16022198. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 5. See the NIHR Journals Library website for further project information.

The role of the vasopressin system and dopamine D1 receptors in the effects of social housing condition on morphine reward.

BACKGROUND: The association with opioid-abusing individuals or even the perception of opioid abuse by peers are risk factors for the initiation and escalation of abuse. Similarly, we demonstrated that morphine-treated animals housed with only morphine-treated animals (referred to as morphine only) acquire morphine conditioned place-preference (CPP) more readily than morphine-treated animals housed with drug-naïve animals (referred to as morphine cage-mates). However, the molecular mechanisms underlying these effects are still elusive. METHODS: Mice received repeated morphine or saline while housed as saline only, morphine only, or cage-mates. Then, they were examined for the expression levels of D1 dopamine receptor (D1DR), D2 dopamine receptor (D2DR), dopamine transporter (DAT), oxytocin, and Arginine-vasopressin (AVP) in the striatum using qPCR. Additionally, we examined the effects of the AVP-V1b receptor antagonist, SSR149415, on the acquisition of morphine conditioned place-preference (CPP). RESULTS: Increased striatal expression of D1DR and AVP was observed in morphine only animals, but not morphine cage-mates. No significant effects were observed on the striatal expression of D2DR, DAT, or oxytocin. Antagonizing the AVP-V1b receptors decreased the acquisition of morphine CPP in the morphine only mice, but did not alter the acquisition of morphine CPP in the morphine cage-mate mice. CONCLUSIONS: Housing with drug-naïve animals protects against the increase in striatal expression of D1DR and AVP elicited by morphine exposure. Moreover, our studies suggest that the protective effect of housing with drug-naïve animals on the acquisition of morphine reward might be, at least partially, mediated by AVP.

The GHR-R antagonist JMV 2959 neither induces malaise nor alters the malaise property of LiCl in the adult male rat.

The orexigenic peptide ghrelin (GHR) interacts with ghrelin receptors (GHR-Rs) to modulate brain reinforcement and feeding circuits. Pharmacological inactivation of GHR-Rs via administration of the drug JMV 2959 attenuates the rewarding/reinforcing effects of several drugs of abuse including alcohol, morphine, amphetamine and nicotine. One view of these results is that inactivation of GHR-Rs taps into brain reinforcement/feeding circuits acted upon by drugs of abuse. An alternate explanation is that JMV 2959 may induce malaise, which in turn may limit reinforcement as well as food ingestion. This is a variable of interest given that nicotine alone can induce malaise which may be enhanced by JMV 2959. In the present study, we assessed the capacity of JMV 2959 to produce malaise using a conditioned taste aversion (CTA) task. Adult male rats were allowed to consume a 0.1% sodium saccharin solution and then injected IP with either vehicle, 0.4mg/kg nicotine, 3mg/kg JMV 2959, a combination of 0.4mg/kg nicotine and 3mg/kg JMV 2959, or 32mg/kg lithium chloride (a positive control known to support induction of CTA). Lithium chloride produced a robust avoidance of the saccharin solution in subsequent 2 bottle (water and saccharin) tests, whereas JMV 2959 alone did not induce CTA. The combination of JMV 2959 and nicotine induced a moderate degree of CTA that was similar to that produced by nicotine alone. These results suggest that JMV 2959 is unlikely to limit either reinforcement or food ingestion via induction of malaise.

Inhibiting social support from massage-like stroking increases morphine dependence.

Our previous studies showed that altering solely the drug experience of the cage mates with which rodents are housed affects the development of morphine dependence. In this study, we used designer receptors exclusively activated by designer drugs to artificially increase or decrease the activity of peripheral dorsal root ganglia sensory neurons expressing the G-protein-coupled receptor MRGPRB4. This is because sensory MRGPRB4-expressing neurons were shown to specifically detect the sensation of massage-like stroking resulting from social grooming, which is an important affiliative social behavior in the rodent. Blocking the sensation of social grooming in morphine-treated mice housed with drug-naive mice (i.e. morphine cage mates) significantly increased the display of jumping behavior in morphine-withdrawn animals. Activating the sensation of social grooming in morphine-treated animals housed solely with other morphine-treated animals (i.e. morphine only) did not significantly alter the display of jumping behavior in morphine-withdrawn animals. Repetitive jumping behaviors have been shown to correlate with morphine dependence. Thus, this study showed a role of social grooming in the protective effect of being housed with drug-naive mice on the development of morphine dependence. It further confirms a role of social support in the development of substance use problems.

Hydrocodone is More Effective than Morphine or Oxycodone in Suppressing the Development of Burn-Induced Mechanical Allodynia.

BACKGROUND: Pain is the most frequent complaint of burn-injured patients. Opioids are commonly used in the course of treatment. However, there is a lack of rodent studies that examine the differential effects of various opioids on burn pain. OBJECTIVE: This study compared the ability of morphine, oxycodone, and hydrocodone to suppress the development of burn-induced mechanical allodynia and reduce pain sensitivity. METHODS: Mice were examined for their baseline pain sensitivity thresholds using the von Frey Filaments test. Then, they were subjected to burn or sham injury and treated orally with morphine, oxycodone, hydrocodone (20 or 40 mg/kg), or saline twice daily throughout the study. They were retested on days 4, 7, 11, 14, 21, and 28 postburn. RESULTS: In the sham animals, morphine produced significant opioid-induced hyperalgesia (OIH). Development of OIH was minimal for hydrocodone and was not observed for oxycodone. Secondary mechanical allodynia was observed beginning four days after the burn injury and intensified with time. All opioids produced comparable antinociceptive effects. Hydrocodone was effective in suppressing the development of burn-induced mechanical allodynia and fully treated the burn-induced increase in pain sensitivity. In contrast, morphine and oxycodone had only minimal effects on the development of burn-induced mechanical allodynia and only partially treated the burn-induced increase in pain sensitivity. CONCLUSIONS: This study demonstrated that hydrocodone is effective in suppressing the development of burn-induced mechanical allodynia, while both morphine and oxycodone had minimal effects. These findings underscore the need for additional studies on the differences among various opioids using clinically relevant pain models.

Hydrocodone, but Neither Morphine nor Oxycodone, Is Effective in Suppressing Burn-Induced Mechanical Allodynia in the Uninjured Foot Contralateral to the Burn.

Opioids are commonly used to treat severe, burn-induced pain. However, there is a lack of rodent studies that examine the differential effects of various opioids on burn pain. We recently demonstrated that hydrocodone was superior to other opioids in suppressing the development of burn-induced mechanical allodynia in the burned limb. This study monitored the development of mechanical allodynia and compared the abilities of morphine, oxycodone, and hydrocodone to reduce burn-induced mechanical allodynia in the limb contralateral to the burn. Mice were examined for their baseline pain sensitivity thresholds using the von Frey filaments test. Then, they were subjected to burn or sham injury and treated orally with morphine, oxycodone, hydrocodone (20 or 40 mg/kg), or saline twice daily throughout the study. They were retested on days 4, 7, 11, 14, 21, and 28 postburn. Hyperalgesia was developed in the contralateral, uninjured foot beginning 21 days after the burn injury. Hydrocodone was effective in suppressing the development of burn-induced mechanical allodynia. In contrast, morphine and oxycodone had only minimal effects on the development of burn-induced mechanical allodynia. The abnormal pain sensitivities that develop as a result of burn injuries are very difficult to treat and remain a significant public health problem. More rodent studies are required to improve our understanding of the differences among the currently available opioid analgesics in order to optimize the care provided to burn victims as well as those suffering from other pain modalities.