Chemical Classes

Acidity/basicity, or the ability to influence pH is one of the most important characteristics of chemical, which must be considered in effective wound management. It should also be noted that concentration also plays an important role.

Acids

Acids are proton donors, so they release hydrogen ions and reduce pH from a neutral 7 down to values as low as 0. Hydrogen ions will catalyse protein hydrolysis into amino acids. Other effects as seen in concentrated sulfuric acid injuries include heat generation and desiccation, producing a mixed injury.

Tungstic, picric, sulfosalicylic, tannic, trichlopacetic, and cresylic acids are all strong protoplasmic poisons which form hard eschars. These acids can be absorbed producing renal and hepatic injury. Most have a very pungent odor.

Treatment Acid Burns

irrigation with water reassess depth keep patient warm

Alkali

Multiple chemical agents are involved in caustic alkali burns. Lime, potassium hydroxide, and sodium hydroxide are the most common agents causing chemical injury. Accidental injury occurs in infants and toddlers. Among chemical burns, alkali injuries occur frequently and are likely to cause severe symptoms. The mechanism by which these alkali injuries are caused is due to three factors:

• saponification of fat causes fatty tissue to lose its function with increased damage due to heat reaction.
• extraction of water from cells causing dessication
• bind with the proteins of the tissues to form alkaline proteinates.

The extent of the damage caused by an alkali substance depends on its concentration, amount, and time of contact with the skin.

As with other chemical burns, alkalis are capable of deep penetration, and can cause severe pain. For treatment, it is necessary to remove the causative substance as quickly as possible by washing with large volumes of water. Washing is presumed to cause dilution and elimination of a chemical substance.

The initial treatment for burns caused by strong alkaline solution is copious irrigation with water. Water may dissipate any heat by dilution so as to prevent further damage. In lime burns, the dry lime must be brushed away before washing in order to minimize the production of heat. The most readily available material for removing a chemical agent is water, and it is extremely important to remove a chemical agent as

rapidly as possible. Washing with large quantities of water is the preferred treatment. It is very difficult to determine the depth of tissue damage on admission. The corrosive material blackens the skin, rapidly converting it to a hard, dry eschar.

Ocular damage is a common sequel to alkali injury. Damage is related to the pH: the higher the pH, the greater the damage to the eye. The corrosive agent trickles down the eyelid and enters the acanthi. Alkalis penetrates quickly and, with little resistance.

Such damage may be made worse by repeated attempts to wipe off the chemical agent with the hands or inadequately washing the eyes. The policy is to treat with topical anesthetics followed by copious irrigation, inducation of cycloplegia and mydriasis as soon as possible.

Cement

Cement is an alkali, but warrants special mention. Cement (calcium oxide) penetrates clothing and reacts with sweat, and an exothermic reaction takes place releasing heat. The dry powder will cause a desiccation injury if not exposed to moisture. Hydrated calcium oxide becomes calcium hydroxide. An injury progresses as with a strong alkali, and the critical substance responsible for skin damage is the hydroxyl ion. Typically the victim does not know for hours that a burn has occurred as it is often a painless process, under clothing. Treatment consists of removal of contaminated clothing and washing the burn area with soap and water. Surgical excision is likely to be required as these injuries are often deeper than they first appear.