AbstractBackground and aimsThe nociceptive system appears to have evolved a range of protective characteristics that are of great interest in understanding both acute and chronic pain. Spatial summation is one important characteristic, whereby increasing area of a stimulus, or distance between multiple stimuli, results in more intense pain—not only greater area of pain. One of the mysteries of chronic pain is why spinal pain is so prevalent relative to pain at other sites. Since pathological tissue models have failed to fully explain spinal pain, we theorized that body region specific differences in sensory processing—such as a greater propensity for spatial summation—may help to explain its vulnerability. We aimed to examine this by comparing the properties of summation at different body parts: the dorsal forearm, neck, and back.MethodsSpatial summation of pain was investigated using noxious intra-dermal electrical stimuli in healthy pain-free adults (14 males, 6 females), and the perceived pain intensity was rated on a 0-100 pain scale. Area-based stimulation was investigated by doubling the stimulation area with the addition of a second electrode placed adjacent to the first. Distance-based summation was investigated by randomly varying the separation distance between paired noxious electrical stimuli at separations of 0,10,15, and 20 cm.ResultsThis study demonstrated that the properties of area- and distance-based summation are uniform across the neck, back, and forearm in healthy adults. Spatial summation of pain was also found to be greatest at 15- and 20-cm paired separations for all body regions tested, confirming that noxious information can be integrated over an extensive anatomical area.ConclusionData from this investigation refutes the thesis that spatial summation of pain may be a contributing factor for the reported difference in chronicity rates between spinal and peripheral sites. It remains, however, a potentially important mechanism by which noxious inputs from multi-level pathology might integrate and contribute to pain.ImplicationsWhile data from this project suggest that there are no regional differences in the properties of spatial summation of noxious stimuli, regional differences in other characteristics of the nociceptive system may yet provide insight into why some spinal pain is so highly prevalent; nociceptive distance-based summation may be highly relevant where two or more conditions co-exist in close proximity.

BackgroundBurns are a painful and traumatic experience, particularly in children. Reduced pain and anxiety positively influences re-epithelialisation rates in paediatric burn patients, however current literature fails to fully explain the effects of pain and anxiety and their links with wound healing. This study will determine if Burnaid® hydrogel dressing is an effective treatment for reducing pain in the acute period of a burn injury. It is hypothesised that a reduction in pain will then improve re-epithelialisation time in comparison to plastic wrap, which is standard practice at our institution — a metropolitan tertiary paediatric hospital located in Brisbane, Australia.Methods/designA randomised controlled trial will be conducted to assess the effectiveness of Burnaid® as an analgesic adjunct to cold running water first aid for the treatment of paediatric burns. Participants will include children aged between 0 and 16 years with an acute thermal burn injury (total burn surface area < 20%) presenting to the Department of Emergency within 24 h of the burn occurring. Participants will be randomised into one of two groups: (1) Burnaid® hydrogel (intervention arm) or (2) plastic wrap (control arm). Participants will also be stratified into one of two groups based on factors that influence pain intensity: (1) high pain risk or (2) low pain risk. High pain risk factors include foot burns, hot coal/ash/fire pit burns, burn area greater than 5%, and circumferential burns. The primary outcome is the intervention’s effect on reducing acute pain. Secondary outcomes include days to re-epithelialisation, pulse rate, temperature, salivary cortisol and α-amylase, anxiety, and cost-effectiveness. Sample size calculations have shown that 36 participants will be recruited into each group.DiscussionThis study will provide comprehensive data on the analgesic properties of Burnaid® as an adjunct to first aid for the treatment of acute paediatric thermal burns. If the intervention is effective in reducing pain, Burnaid® will be integrated as standard practice within the hospital’s Department of Emergency. This study replicates a real-world scenario in order to identify clinically significant analgesic and wound-healing effects.Trial registrationAustralian New Zealand Clinical Trials Registry, ACTRN12617001274369. Prospectively registered on 5 Sept 2017.Electronic supplementary materialThe online version of this article (10.1186/s13063-018-3057-x) contains supplementary material, which is available to authorized users.

IntroductionThere is an absence of evidence regarding predictors of moderate to severe pain in children undergoing acute burn treatment. This investigation aimed to determine if relationships existed between patient and clinical characteristics, and pain at first dressing change for children with acute burn injuries.MethodsA retrospective cohort investigation was conducted using clinical data from pediatric burn patients treated at the Queensland Children’s Hospital, Brisbane, Australia. Data extracted included patient and burn characteristics, first aid, and follow-up care. Observational pain scores were categorized into three groups (mild, moderate, and severe pain), and bivariate and multivariable relationships were examined using proportional odds ordinal logistic regression. Data from 2013 pediatric burns patients were extracted from the database.ResultsFactors associated with increased odds of procedural pain included: hand burns (OR 1.7, 95% CI 1.3 to 2.1, p<0.001), foot burns (OR 1.5, 95% CI 1.1 to 2.1, p<0.01), baseline pain (OR 5.5, 95% CI 2.8 to 10.8, p<0.001), deep dermal partial-thickness injuries (OR 7.9, 95% CI 4.0 to 15.6, p<0.001), increased burn size (OR 1.1, 95% CI 1.0 to 1.2, p<0.01), four or more anatomical regions burned (OR 3.6, 95% CI 1.5 to 8.6, p<0.01), initial treatment at a non-burns center (OR 1.8, 95% CI 1.4 to 2.3, p<0.001), and time to hospital presentation (OR 0.9, 95% CI 0.8 to 0.9, p<0.001). These burn characteristics are associated with increased odds of moderate to severe procedural pain during a child’s first dressings change.DiscussionIt is recommended that patients presenting with one or more of the aforementioned factors are identified before their first dressing change, so additional pain control methods can be implemented.