152		S. Shahrokhi
Table 9.4 Classes of chemicals and their mechanisms of tissue injury
Class of chemical		Mechanism of tissue injury
Acid		Coagulation necrosis
Alkali		Liquefaction necrosis – deeper penetration and more severe burns
Organic solutions		Dissolve lipid membranes
Inorganic solutions		Direct binding and salt formation
Table 9.5 Management principles for chemical burns
Removal of	Removal of involved clothing
chemical agent	Thorough and copious irrigation with water except for:
		Phenol – wipe off with 50 % polyethylene glycol sponges [34]
		Dry lime – dust off prior to lavage [35, 36]
		Muriatic acid, sulfuric acid – neutralize with soap or lime water [35, 36]
Systemic	HF acid – hypocalcemia and ventricular fibrillation [37]
toxicity	Formic acid – intravascular hemolysis, renal failure, pancreatitis [38]
	Organic solutions and hydrocarbures – liver failure [30]
	Respiratory injury – can occur with all inhaled agents and must be treated in
	same manner as inhalation injury [30]
Antidotes	Hydrofluoric acid – inject 10 % calcium gluconate sub-eschar
	White phosphorus – lavage with 1–2 % copper sulfate
Wound care	Wound dressing as for thermal burns
	Early excision of nonviable tissue

Ophthalmology consult for ocular involvement [39, 40] in addition to copious irrigation

9.3Cold Injury (Frostbite)

Frostbite is part of the spectrum of localized cold injury, which is associated with the greatest amount of tissue destruction. The mechanisms proposed for tissue injury are:

•Cellular death secondary to cold exposure [41, 42, 45]

•Progressive dermal ischemia [41, 42]

The clinical manifestations of frostbite are as a result of thrombotic events

secondary to ischemia/reperfusion injury [41–44] and are classified into four degrees:

•First degree – anesthetic central white plaque with peripheral erythema

•Second degree – blisters surrounded by erythema and edema

•Third degree – hemorrhagic blisters followed by eschar

•Fourth degree – necrosis and tissue loss

• The common risk factors associated with development of frostbite are [41, 42, 49]:

•Mental illness

•Alcohol/drug intoxication

•Extreme of age