Using ordinal logistic regression to evaluate the performance of laser-Doppler predictions of burn-healing time.

BACKGROUND: Laser-Doppler imaging (LDI) of cutaneous blood flow is beginning to be used by burn surgeons to predict the healing time of burn wounds; predicted healing time is used to determine wound treatment as either dressings or surgery. In this paper, we do a statistical analysis of the performance of the technique. METHODS: We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool. RESULTS: Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA), site and cause of burn, day of LDI scan, burn center). It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small. CONCLUSION: Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for.The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the percentage of correct diagnoses.

The impact of recent legislation on paediatric fireworks injuries in the Newcastle upon Tyne region.

Despite the changes to the UK fireworks laws and considerable efforts in prevention, children are still being injured by fireworks. The UK is one of many countries that have altered their firework laws in recent years. We reviewed 54 firework-injured children over the last 10 years and assessed the impact of the two recent UK law changes. Our study outlines past British firework legislation and reviews the literature. In November 1996, there were three deaths in England, Wales and Scotland due to fireworks. The British Government introduced the Fireworks (Safety) Regulations of 1996/1997, primarily banning banger fireworks (known as bangers). We have not seen banger injuries in Newcastle since then. The Fireworks Act 2003 and the Fireworks Regulations 2004 limited the sale of fireworks to the 3 weeks surrounding bonfire night, and banned under 18s from purchasing or possessing fireworks. In our series, we noticed that, in 2004, 83% of children's firework injuries happened in the 3 weeks surrounding Bonfire Night. We conclude that legislation has had an impact, but stricter enforcement of the existing laws and further education of children and the general public into the dangers of fireworks is needed, as children are still being injured.

Evidence for the link between healing time and the development of hypertrophic scars (HTS) in paediatric burns due to scald injury.

The relationship between burn depth, healing time and the development of hypertrophic scarring (HTS) is well recognised by burn surgeons but is seldom mentioned in the published literature. We studied 337 children with scalds whose scars were monitored for up to 5 years. Overall HTS rates were found to be: under 10 days to healing=0%, 10-14 days=8%, 15-21 days=20%, 22-25 days=40%, 26-30 days=68% and over 30 days=92%. In the conservatively treated group the HTS rates are: under 10 days=0%, 10-14 days=2%, 15-21 days=20%, 22-25 days=28%, 26-30 days=75% and over 30 days=94%. If skin grafting is undertaken there is a much higher incidence of HTS in the 10-14 days group: 10-14 days=33%, 15-21 days=19%, 22-25 days=54%, 26-30 days=64% and over 30 days=88%. We conclude that there is a low risk of HTS formation in scalds healed before 21 days, and that surgery should be reserved for scalds likely to take more than 21 days to heal.

Dermal preservation using the Versajet hydrosurgery system for debridement of paediatric burns.

Loss of dermis is one of the principal factors that contributes to poor scar outcome after severe burn. Dermal loss may be due to the primary injury, surgical management or as a result of infection. Strategies for dermal preservation are therefore important to improve scar quality. We report our early experience using the Versajet hydrosurgery system, to preserve dermal tissues, both directly during surgical debridement and indirectly by reducing infection and optimising the use of biological dressings. In deep partial thickness burns softer necrotic dermis can be removed with the Versajet sparing the underlying tougher viable dermis. In superficial burns the Versajet cleans and removes loose epidermal elements providing an optimal wound surface for the application of biological dressings, even a number of days after injury. Versajet is most useful when the tissue to be removed is softer than that to be left behind.