Chemical burn is defined as acute injury of the skin or mucous membranes caused by primary contact with certain chemical materials and subsequent chemical reaction specific to the materials without heat reaction. The causal materials are classified into acids, alkaline compounds, corrosive aromatic compounds, aliphatic compounds, aromatic hydrocarbons, petroleum-related products, metals and metallic compounds, non-metals and non-metal compounds, chemical weapons (poisonous gas) and others. The clinical image is similar to that of common burns caused by heat. However, it is necessary to know the characteristics of individual materials because some causal chemicals exhibit characteristic clinical features and/or have the possibility of systemic poisoning after absorption through the skin. The principle of treatment is washing with running water as soon as possible and special treatments for some specific chemical burns. For plastic surgeons, dermatologists, ER doctors, general physicians and surgeons with opportunities to treat chemical burn patients, it is necessary to have the minimum knowledge about chemical burns.
Bright illumination sources using xenon lamps have improved microsurgical visualization under operating microscopes; however, surgeons must recognize the potential for accidental thermal damage to soft tissues. In this article, we present two reports of microscopic thermal burn in lymphaticovenular anastomosis (LVA) . We also present our simple method to prevent this injury. A 23-year-old woman and a 57-year-old woman with bilateral lymphedema of the legs had LVAs on both legs under local anesthesia. The burn wound in the 23-year-old woman was a full-thickness burn and that in the 57-year-old woman was a deep dermal burn. Both healed without skin grafting. The working distance and high illumination intensity are important risk factors. The use of epinephrine as part of the local anesthetic mixture that reduces blood flow is also a major risk factor for thermal burns. LVA in particular requires high magnification, which leads to an increased intensity and closer working distance. The surgical conditions for LVA make patients prone to microscope-induced thermal burns.
We statistically analyzed data for 50,376 burn patients over a 26-year period (April 1, 1993 to March 31, 2019) ; the patients’ first visit to a clinic fell within the specified period. In 2018, 25-year data on burn patients was aggregated at the 44th Annual Meeting of the Japanese Society for Burn Injuries. Combined with the number of patients recorded in the following year, the total was 50,376. We present the aggregated data in this report.
There were 17,437 male patients and 32,939 female patients, with a gender ratio of 0.53.
The most prevalent age group was ≤ years (approximately 15,936 patients［31.6%］) . The gender ratio in this age group was 1.02, demonstrating an equal number of males and females. The major causes of burn injuries were as follows: hot liquids in 24,105 (47.9%) , hot solids in 17,656 (35.1%) , fire/flame in 3,784 (7.5%) , and hot gases in 2,679 (5.9% ) . These four causes accounted for 95.7% of all burn injuries. Of the 24,105 burns caused by hot liquids (the most prevalent cause) , 10,581 were caused by hot water, 6,023 were caused by hot oil, 2,084 were caused by hot tea/coffee, and 1,439 were caused by hot miso soup.
Of the 17,656 burns caused by hot solids, 5,198 were caused by heating appliances, 2,258 were caused by irons, 1,070 were caused by fireworks, and 608 were caused by steam from a rice cooker. The number of burn patients recorded in FY2018（n=1,245）was less than half of that recorded in FY1993（n=2,690）. In the first year, 46.3% patients were recorded. In addition to aggregating a large number of patients, we considered it important to examine the fluctuations during this period.
We therefore performed statistical analysis by dividing the 26-year duration into two parts, the first and second periods. The total number of patients in the first and second periods was 29,836 and 20,540（68.8% of the number recorded in the first period）, respectively. When analyzed by gender, the number of male patients in the second period was 60.2% of that recorded in the first period, whereas the number of female patients in the second period was 73.8% of that recorded in the first period, revealing considerable decrease rates. When analyzed by cause, the rate of decrease was substantial in burn injuries caused by fire/flame（51.2%）and explosion（37.5%）.
The number of burn injuries caused by stoves in the second period was 44.0% of that recorded in the first period. However, the number of burn injuries caused by hair irons in the second period increased to 1,100% of that recorded in the first period.
We present the case of a 37-year-old male patient who sustained deep burns (2%) on the dorsal surface of both hands and fingers during a fire accident at work. Six hours after the injury, debridement was performed and artificial dermis was applied. On day 3, post-burn rehabilitation was started by a physiotherapist and occupational therapist, and performed once daily when the wound was cleaned. Pain was managed using oral analgesics; intravenous anesthetics were also used during rehabilitation. However, it was difficult to continue rehabilitation because of right hand pain. Therefore, continuous peripheral nerve block was started for the right radial and ulnar nerves from day 8 to 13 post-burn. Thus, the pain was well controlled and rehabilitation was able to be continued. Full-thickness skin grafting was performed on day 13 post-burn. On day 111 post-burn, his grip strength had improved to 43 kg in the right hand and 42 kg in the left hand, with almost no limitation in the range of motion. Continuous peripheral nerve block can provide good pain control under consciousness and is useful for early rehabilitation for functional preservation.