With burn injuries there are five heat categories: Thermal, Chemical, Mechanical, Electrical and Radiation.

Thermal

This source is divided into two categories - Dry Thermal and Wet Thermal injuries. Dry thermal will involve flame, very hot objects, and radiant heat. Wet thermal will involve steam and hot liquids. (Steam is of a major concern, it has the capacity to carry 4000 times more heat than dry air)

When managing dry thermal injuries the following points should be considered: all burnt clothing, and foreign objects adherering to the burn location must not be removed; the body's defence mechanism will start to send fluids to the site; thus causing oedema; in those circumstances where there is a concern that constrictive clothing, jewellery, footwear etc. will prevent circulation tp and beyond the location, cut the constricting item of jewellery or clothing etc. and allow it to expand on site.

Wet thermal injuries are caused by hot liquids such as boiling water, coffee, tea, soup, chip pan oil, tar, molten liquids etc.. If clothing is saturated it will have to be cooled (to protect also the rescuer) and carefully removed, otherwise it will continue to act as a heat source. If possible try not to deroof underlying blisters. With an exposed scald injury immediate cooling can be started.

Chemical

The source for this category is all chemicals both wet and dry, alkalis and hydrocarbons and phenols (industrial cleaners, solvents, degreasing agents, petrol etc). Chemical burns are not usually thermic, but are caused by tissue reaction to noxious substances, the amount of tissue damage will depend on the chemical and exposure time. This category is an anomaly in that full irrigation of all liquid chemical burn sites must take place prior to cooling, large amounts of flowing water will be required to wash away and break down the liquid chemical or chemicals in question. It is worth considering using warm water for irrigation as this will help to protect the core temperature of the patient, e.g. domestic shower.

If possible, remove all saturated clothing, footwear, watches, jewellery etc. from the patient. Dry chemicals will not be irrigated, only brushed off the patient. Once full brushing has taken place there will be a residual burn, this site will then be managed by the standard recognised protocols. If there is a considerable spill of hazardous chemical you should notify the local county fire service.

Mechanical

The main source of a mechanical burn will be surface friction, e.g. carpet burns, plastic playing pitches, rope burns, RTA involving motor cyclists. Mechanical burns will always occur where the skin is in contact with a surface moving quickly in the opposite direction.

Electrical

Patients in this category will usually have been in contact with one of the following two sources of electricity: alternating current (AC) and direct current (DC). Electrical injuries can be classified into three groups: True Electrical Injury, Arc Burn and Electrical Thermal Burn.

True electrical injury occurs when electricity passes through the body after contact with an electrical conductor. This burn will present the classic entry and exit wounds, along with deep tissue destruction. because the entry and exit wounds have been cauterised, the patient may not be able to say where the exit wound is, because the wound sites are in a semi-anaesthetic state. However, they may complain of an aching pain in their heel or toe or some other location, this is usually the point of exit.

With an Arc burn, the victim is not in actual contact with electricity, but occupies the space where there is a differential electrical potential between the victim and the electrical source. These injuries are most common with high tension current. There may be an entry and exit wound. Usually there are scattered spots of injury where the current made momentary contact as it jumped to ground. Note: extremely deep burns can occur if the arc is close to the body.

Electrical thermal burns are caused by sparks or electrical arcing close to the body which ignites clothing or results in facial blast. Cardiac complications should always be considered when called to an electrical burn injury, on arrival make sure that the power supply is disconnected at the mains before approaching the patient having insured that the scene is safe.