Burn injury

Overview

This Primer on burn injury, published in Nature Reviews Disease Primers in 2020 by Jeschke and colleagues, gives an overview of the epidemiology, mechanisms, diagnosis, management and long-term outcomes of burns and highlights the remaining challenges. Burns are under-appreciated injuries with substantial morbidity and mortality, and patients are not recovered when the wounds have healed, because burns lead to long-term physical, mental and quality-of-life changes. The WHO estimates 11 million burn injuries and 180,000 deaths a year, with about 90% of burns in low- and middle-income countries.

Classification and pathophysiology

Burns are classified by cause, depth (superficial to fourth-degree) and size. A major burn is not well defined, but guidance is more than 10% TBSA in the elderly, more than 20% in adults and more than 30% in children. Severe burns cause a dysregulated inflammatory response, distributive shock with capillary leak, depressed cardiac function in the first 24 to 48 hours, immune dysfunction with a high infection risk and a hypermetabolic, catabolic state that can last up to 36 months. Inhalation injury, other trauma and gut-derived bacteria add to the burden, and infection and multiple organ failure cause most deaths.

Diagnosis and prevention

Assessment follows the primary and secondary survey (ATLS and ABLS), with burn size estimated by the Lund and Browder diagram in children and the rule of nines in adults. Estimates by non-experts are often inaccurate, and tools such as laser Doppler imaging are being studied for depth. Smoke inhalation is suspected from stridor, hoarseness, carbonaceous sputum and pharyngeal findings. Most burns are preventable, and prevention programmes should be matched to local causes using the Haddon matrix.

Management

Care has five phases: acute assessment, resuscitation, wound coverage, supportive critical care and rehabilitation. Resuscitation uses a balanced crystalloid (warmed Ringer's lactate) with an initial rate from formulae (2 to 4 mL/kg per %TBSA over 24 hours, or the Rule of Tens) titrated to a urine output of 0.3 to 0.5 mL/kg/h, with colloid rescue considered to avoid over-resuscitation. Early excision and autografting is the gold standard for deep burns, with allograft, Meek meshing, dermal matrices and cultured skin used for large burns. Prophylactic systemic antibiotics are not used.

Long-term outcome

Hypertrophic scars occur in 30 to 90% of burns, and keloids mainly in darker skin. Early physical and occupational therapy limits contractures. Burn survivors report lower quality of life, more anxiety and depression and higher long-term mortality, and 66 to 74% return to work. The authors call for global registries, better tools for assessing burn depth, prediction of sepsis and attention to long-term care.