Respiratory Morbidity After Childhood Burns: A 10-Year Follow-up Study

Unremitting pro-inflammatory T-cell phenotypes, and macrophage activity, following paediatric burn injury

Objectives

The aim of this study was to characterise the dynamic immune profile of paediatric burn patients for up to 18 months post-burn.

Methods

Flow cytometry was used to measure 25 cell markers, chemokines and cytokines which reflected both pro-inflammatory and anti-inflammatory immune profiles. Peripheral blood mononuclear cells from 6 paediatric burn patients who had returned for repeated burn and scar treatments for > 4 timepoints within 12 months post-burn were compared to four age-matched healthy controls.

Results

While overall proportions of T cells, NK cells and macrophages remained relatively constant, over time percentages of these immune cells differentiated into effector and proinflammatory cell phenotypes including Th17 and activated γδ T cells. Circulating proportions of γδ T cells increased their expression of pro-inflammatory mediators throughout the burn recovery, with a 3-6 fold increase of IL-17 at 1-3 weeks, and NFκβ 9-18 months post-burn. T-regulatory cell plasticity was also observed, and Treg phenotype proportions changed from systemically reduced skin-homing T-regs (CCR4+) and increased inflammatory (CCR6+) at 1-month post-burn, to double-positive cell types (CCR4+CCR6+) elevated in circulation for 18 months post-burn. Furthermore, Tregs were observed to proportionally express less IL-10 but increased TNF-α over 18 months.

Conclusion

Overall, these results indicate the circulating percentages of immune cells do not increase or decrease over time post-burn, instead they become highly specialised, inflammatory and skin-homing. In this patient population, these changes persisted for at least 18 months post-burn, this 'immune distraction' may limit the ability of immune cells to prioritise other threats post-burn, such as respiratory infections.

Six Months of Exercise Training Improves Ventilatory Responses during Exercise in Adults with Well-Healed Burn Injuries

INTRODUCTION

Pulmonary function is lower after a severe burn injury, which could influence ventilatory responses during exercise. It is unclear whether exercise training improves pulmonary function or ventilatory responses during exercise in adults with well-healed burn injuries. Therefore, we tested the hypothesis that exercise training improves pulmonary function and ventilatory responses during exercise in adults with well-healed burn injuries.

METHODS

Thirty-nine adults (28 with well-healed burn injuries and 11 non-burn-injured controls) completed 6 months of unsupervised, progressive exercise training including endurance, resistance, and high-intensity interval components. Before and after exercise training, we performed comprehensive pulmonary function testing and measured ventilatory responses during cycling exercise. We compared variables using two-way ANOVA (group-time; i.e., preexercise/postexercise training (repeated factor)).

RESULTS

Exercise training did not increase percent predicted spirometry, lung diffusing capacity, or airway resistance measures (time: P ≥ 0.14 for all variables). However, exercise training reduced minute ventilation ( V̇E ; time: P ≤ 0.05 for 50 and 75 W) and the ventilatory equivalent for oxygen ( V̇E /V̇O 2 ; time: P < 0.001 for 75 W) during fixed-load exercise for both groups. The ventilatory equivalent for carbon dioxide ( V̇E /V̇CO 2 ) during exercise at 75 W was reduced after exercise training (time: P = 0.04). The percentage of age-predicted maximum heart rate at the ventilatory threshold was lower in adults with well-healed burn injuries before ( P = 0.002), but not after ( P = 0.22), exercise training. Lastly, exercise training increased V̇E and reduced V̇E /V̇O 2 during maximal exercise (time: P = 0.005 for both variables).

CONCLUSIONS

These novel findings demonstrate that exercise training can improve ventilatory responses during exercise in adults with well-healed burn injuries.

Systemic long-term metabolic effects of acute non-severe paediatric burn injury

A growing body of evidence supports the concept of a systemic response to non-severe thermal trauma. This provokes an immunosuppressed state that predisposes paediatric patients to poor recovery and increased risk of secondary morbidity. In this study, to understand the long-term systemic effects of non-severe burns in children, targeted mass spectrometry assays for biogenic amines and tryptophan metabolites were performed on plasma collected from child burn patients at least three years post injury and compared to age and sex matched non-burn (healthy) controls. A panel of 12 metabolites, including urea cycle intermediates, aromatic amino acids and quinolinic acid were present in significantly higher concentrations in children with previous burn injury. Correlation analysis of metabolite levels to previously measured cytokine levels indicated the presence of multiple cytokine-metabolite associations in the burn injury participants that were absent from the healthy controls. These data suggest that there is a sustained immunometabolic imprint of non-severe burn trauma, potentially linked to long-term immune changes that may contribute to the poor long-term health outcomes observed in children after burn injury.

Grip strength in children after non-severe burn injury

PURPOSE

To characterise grip strength in children with non-severe burn injury, and further understanding of how demographic and clinical variables impact musculoskeletal recovery.

METHODS

A retrospective, cross-sectional audit of routinely collected clinical data was performed. Standardised protocols were used to measure height, weight and grip strength. Demographic and clinical information was collected from patient medical records. Grip strength comparisons were made against normative data using paired t-tests. General linear regressions with backwards elimination were performed to assess impact of clinical, demographic and physical variables on grip strength.

RESULTS

Children who were right hand (RH) dominant had reduced RH (18.9 ± 9.9 kg, p = 0.001) and left hand (LH)(17.6 ± 9.3 kg, p = 0.027) grip strength compared to age, sex and hand-dominance matched norms (RH, 20.0 ± 10.0 kg; LH, 18.4 ± 9.5 kg). Children who were assessed closer to the time of their injury, and those who were burnt at a young age were more likely to score grip strength values below the norm (p < 0.001 for all analyses). In particular, females appeared to be at a higher risk of low grip strength scores if burnt at a young age (p < 0.001).

CONCLUSIONS

Children with non-severe burn injury struggle to recover musculoskeletal strength, with those who were assessed closer to the time of injury or burnt at a young age especially at risk of impaired grip strength performance. Grip strength does not appear to be influenced by any other clinical variables or burn injury characteristics.

Adults with well-healed burn injuries have lower pulmonary function values decades after injury

Sub-acute (e.g., inhalation injury) and/or acute insults sustained during a severe burn injury impairs pulmonary function. However, previous work has not fully characterized pulmonary function in adults with well-healed burn injuries decades after an injury. Therefore, we tested the hypothesis that adults with well-healed burn injuries have lower pulmonary function years after recovery. Our cohort of adults with well-healed burn-injuries (n = 41) had a lower forced expiratory volume in one second (Burn: 93 ± 16 vs. Control: 103 ± 10%predicted, mean ± SD; d = 0.60, p = 0.04), lower maximal voluntary ventilation (Burn: 84 [71-97] vs. Control: 105 [94-122] %predicted, median [IQR]; d = 0.84, p < 0.01), and a higher specific airway resistance (Burn: 235 ± 80 vs. Control: 179 ± 40%predicted, mean ± SD; d = 0.66, p = 0.02) than non-burned control participants (n = 12). No variables were meaningfully influenced by having a previous inhalation injury (d ≤ 0.44, p ≥ 0.19; 13 of 41 had an inhalation injury), the size of the body surface area burned (R²  ≤ 0.06, p ≥ 0.15; range of 15%-88% body surface area burned), or the time since the burn injury (R²  ≤ 0.04, p ≥ 0.22; range of 2-50 years post-injury). These data suggest that adults with well-healed burn injuries have lower pulmonary function decades after injury. Therefore, future research should examine rehabilitation strategies that could improve pulmonary function among adults with well-healed burn injuries.

Management of non-severe burn wounds in children and adolescents: optimising outcomes through all stages of the patient journey

Paediatric burn injuries are common, especially in children younger than 5 years, and can lead to poor physical and psychosocial outcomes in the long term. In this Review, we aim to summarise the key factors and interventions before hospital admission and following discharge that can improve the long-term outcomes of paediatric burns. Care can be optimised through first aid treatment, correct initial assessment of burn severity, and appropriate patient referral to a burns centre. Scar prevention or treatment and patient follow-up after discharge are also essential. As most burn injuries in children are comparatively small and readily survivable, this Review does not cover the perioperative management associated with severe burns that require fluid resuscitation, or inhalational injury. Burns disproportionately affect children from low socioeconomic backgrounds and those living in low-income and middle-income countries, with ample evidence to suggest that there remains scope for low-cost interventions to improve care for those patients with the greatest burden of burn injury. Current knowledge gaps and future research directions are discussed.

Non-severe burn injury increases cancer incidence in mice and has long-term impacts on the activation and function of T cells

Background

Recent evidence suggests that burn patients are at increased risk of hospital admission for infection, mental health conditions, cardiovascular disease and cancer for many years after discharge for the burn injury itself. Burn injury has also been shown to induce sustained immune system dysfunction. This change to immune function may contribute to the increased risk of chronic disease observed. However, the mechanisms that disrupt long-term immune function in response to burn trauma, and their link to long-term morbidity, remain unknown. In this study we investigated changes to immune function after burn injury using a murine model of non-severe injury.

Methods

An established mouse model of non-severe burn injury (full thickness burn equivalent to 8% total body surface area) was used in combination with an orthotopic model of B16 melanoma to investigate the link between burns and cancer. Considering that CD8⁺ T cells are important drivers of effective tumour suppression in this model, we also investigated potential dysregulation of this immune population using mouse models of burn injury in combination with herpes simplex virus infection. Flow cytometry was used to detect and quantify cell populations of interest and changes in immune function.

Results

We demonstrate that 4 weeks after a non-severe burn injury, mice were significantly more susceptible to tumour development than controls using an orthotopic model of B16 melanoma. In addition, our results reveal that CD8⁺ T cell expansion, differentiation and memory potential is significantly impaired at 1 month post-burn.

Conclusions

Our data suggests that CD8⁺ T cell-mediated immunity may be dysfunctional for a sustained period after even non-severe burn injury. Further studies in patients to validate these findings may support clinical intervention to restore or protect immunity in patients after burn injury and reduce the increased risk of secondary morbidities observed.

Recommendations for influenza vaccination in burns patients based on a systematic review of the evidence

Severe burn injury is a serious systemic insult that can lead to life threatening secondary infections. Immunosuppression, inhalation injury and prolonged length of hospital stay are factors which predispose patients to severe respiratory tract infections. Furthermore, evidence shows that burns can put one at risk of infection long after the original injury. Currently in the United Kingdom, the annual National Flu Immunisation programme outlines guidance for groups who are deemed high risk and therefore eligible for the influenza vaccine. At present, no guidance exists for administration of the influenza vaccine in burn injured patients, despite knowledge of immunosuppression. The aim of this literature review is to examine the evidence for associations between burn injury and influenza and where available, evaluate efficacy of influenza vaccines in this cohort. In addition, literature was searched for the effectiveness of the influenza vaccine in patients 65 years and above, and in patients admitted to the intensive care unit (ICU); two domains common to patients with severe burns. Three papers were found to suggest increased susceptibility to influenza following burn injury, however no papers studying the effectiveness of the influenza vaccine in this group were found. Several studies demonstrated improved outcomes in patients over 65 years and patients admitted to ICU. Following evaluation of the evidence, this review advocates for the consideration of hospitalized burn patients for the influenza vaccine. We suggest avoidance of vaccine administration in the acute burn phase. Further prospective clinical trials would be required to validate these findings.

Predictability of exercise capacity following pediatric burns: a preliminary investigation

PURPOSE

Describe the course of exercise capacity in pediatric burn patients during the initial 6 months after hospital discharge, and examine whether its recovery can be predicted from burn characteristics, sociodemographic characteristics, and/or prior assessment.

MATERIALS AND METHODS

Exercise capacity was assessed at discharge, and 6 weeks, 3 months, and 6 months after discharge using the Steep Ramp Test (SRT).

RESULTS

Twenty-four pediatric patients with burns affecting 0.1-34% of total body surface area were included. At group level, exercise capacity was low at discharge and did not reach healthy reference values within 6 months, despite significant improvement over time. At individual level, the course of exercise capacity varied widely. Six months after discharge, 48% of participants scored more than one standard deviation below healthy age- and sex-specific reference values. SRT outcomes at 6 weeks and 3 months were the best predictors of exercise capacity 6 months after discharge, explaining, respectively, 76% and 93% of variance.

CONCLUSIONS

Forty-eight percent of participants did not achieve healthy reference values of exercise capacity and were therefore considered "at risk" for diminished functioning. Our preliminary conclusion that early assessment of exercise capacity with the SRT can timely identify those patients, needs to be strengthened by further research.IMPLICATIONS FOR REHABILITATIONPediatric burns can be considered as a chronic medical condition because of the lifelong consequences.Exercise capacity is reduced following- even minor -pediatric burns.Recovery patterns vary widely: some pediatric burn patients achieve healthy levels of exercise capacity without specific intervention, while others do not.The Steep Ramp Test can be used to assess exercise capacity, identifying those "at risk" for adverse outcomes at an early stage.Patients "at risk" should be encouraged to play sports and adopt an active lifestyle.

Physical activity and sedentary behavior following pediatric burns - a preliminary investigation using objective activity monitoring

Background

Adequate levels of regular physical activity (PA) are crucial for health and well-being. Pediatric burn injuries can have major physiological consequences in both the short and long term. The question is whether these consequences affect post burn PA levels. This study therefore aimed to describe PA and sedentary behavior (SB) in children and adolescents 1–5 years after burn injury.

Methods

Daily PA and SB were monitored in 20 children and adolescents (12 boys and 8 girls, aged 6–17 years, with burns covering 10–37% of total body surface area, 1–5 years post burn) for 1 week using the ActiGraph GTX3+ accelerometer. Activity counts were categorized into SB, light PA, moderate PA, vigorous PA, moderate-to-vigorous PA (MVPA), and total PA. Outcomes were compared with non-burned reference values and PA levels recommended by the World Health Organization (WHO).

Results

The participants spent about 5.1 h per day on total PA and 7.4 h on SB. Most of the active time (~ 83%) was categorized as light PA. Thirty-five percent of the group, especially the young boys, spent on average ≥ 60 min on MVPA per day. The boys, although with large interindividual differences, spent more time on MVPA than the girls (p < .005). Older age was associated with less PA time, while more time was spent sedentary. No trends were found indicating an effect of burn characteristics, time post burn, or length of hospital stay, and no differences were found with non-burned peers.

Conclusion

Duration and intensity of PA and SB in children and adolescents 1–5 years after burn injury were similar to non-burned peers. However, only 35% of the group met the WHO physical activity recommendation. Given the increased long term risk for physical conditions following pediatric burns, physical activity should be encouraged in this vulnerable population.

Trial registration

The study is registered in the National Academic Research and Collaborations Information System of the Netherlands (OND1348800).

Electronic supplementary material

The online version of this article (10.1186/s13102-018-0093-5) contains supplementary material, which is available to authorized users.