Description, Causes and Risk Factors:
Caustics and corrosives cause tissue injury by a chemical reaction. The vast majority of caustic chemicals are acidic or alkaline substances that damage tissue by accepting a proton (alkaline substance) or donating a proton (acidic substance) in an aqueous solution.
Caustic chemicals produce tissue injury by altering the ionized state and structure of molecules and disrupting covalent bonds. In aqueous solutions, the hydrogen ion (H+) produces the principle toxic effects for the majority of acids, whereas the hydroxide ion (OH-) produces such effects for alkaline substances.
The most common agents implicated in caustic ingestion are cleaning and dishwasher products and industrial paint strippers. Alkalis are also contained in hair straighteners and relaxers, which may be freely accessible to children in the bathroom environment.
Injury patterns for alkali burns differ from those of acid burns. Acids cause coagulative necrosis, which results in a self-limiting burn pattern, while alkalis induce liquefactive necrosis with saponification of fats and solubilization of proteins. These are hygroscopic and absorb water from tissues, resulting in deeper tissue penetration and more extensive burns. Because of increased tissue adherence, alkali also causes more damage to the esophagus, while acid ingestion tends to result in more severe gastric injury. However, deliberate ingestion of large quantities of alkali may injure the stomach and even the small intestine. Gastric injury is more likely to follow ingestion of a liquid than solid alkali.
The severity of injuries depends on multiple factors, such as the concentration of the agent, volume ingested, duration of contact with mucosal surfaces and pH of the solution (damage is greatest when the pH is >12). Solid preparations and viscous liquids produce more severe injury owing to a longer contact time with the oral and oesophageal mucosa.
Ingestions of caustic substances accounted for more toxic exposures than any other class of agents. Cleaning substances, many of which contain potentially caustic agents, account for more than 200,000 exposures per year reported to US poison control centers.
Initial symptoms include drooling and dysphagia
. In severe cases, pain, vomiting, and sometimes bleeding develop immediately in the mouth, throat, chest, or abdomen. Airway burns may cause coughing, tachypnea, or stridor.
Swollen, erythematous tissue may be visible intraorally; however, caustic liquids may cause no intraoral burns despite serious injury farther down the GI tract. Esophageal perforation may result in mediastinitis, with severe chest pain, tachycardia, fever, tachypnea, and shock. Gastric perforation may result in peritonitis. Esophageal or gastric perforation may occur within hours, after weeks, or any time in between.
Esophageal strictures can develop over weeks, even if initial symptoms had been mild and treatment had been adequate.
Plain chest and abdominal x-rays are not sensitive, but may aid in the rapid diagnosis of perforation.
- Contrast studies may also fail to detect perforations, but extravasation of contrast outside of GI tract is diagnostic. Water-soluble contrast is recommended initially as it is less irritating to tissues in case of perforation.
- CT scanning may have a role in the evaluation of caustic injury but has not been studied.
- Endoscopy is the standard diagnostic tool for evaluation of caustic injury. Scope should be performed preferentially within the first 12 hours, but no later than 24 hours (wound softening starting on the 2nd day may increase the risk of perforation).
pH testing of saliva: Unexpected high or low values may confirm ingestion in questionable cases; however, a neutral pH cannot rule out a caustic ingestion.
- Complete blood count (CBC), electrolyte levels, BUN levels, creatinine level, and ABG levels may all be helpful as baseline values and as indications of systemic toxicity.
- Liver function tests and DIC panel may also be helpful to establish baselines or, if abnormal, confirm severe injury following acid ingestions.
- Urinalysis and urine output may help guide fluid replacement.
- Type and cross are indicated for any potential surgical candidates or those with the potential for gastrointestinal bleeding.
- Obtain aspirin and acetaminophen levels as well as an ECG in any patient whose intent may have been suicidal.
- In cases of hydrofluoric acid (HF) ingestion, precipitous falls in calcium level may lead to sudden cardiac arrest. Although ionized calcium levels are likely to have too long a turnaround to be clinically useful, cardiac monitoring and serial ECGs may help anticipate this event.
Attempt to identify the specific product, concentration of active ingredients, and estimated volume and amount ingested. Obtain MSDS sheets when possible for workplace exposures. The product container or labels may be available. Avoid exposure to health care workers.
Do not induce emesis or attempt to neutralize the substance by using a weak acid or base. This induces an exothermic reaction, which can compound the chemical injury with a thermal injury. It may also induce emesis re-exposing tissue to the caustic agent.
Small amounts of a diluent, although controversial, may be beneficial if administered as soon as possible after a solid or granular alkaline ingestion, to remove any adhering particles to the oral or esophageal mucosa. Water or milk may be administered in small amounts. It is very unlikely to be of any benefit after more than 30 minutes.
In the treatment area, patients suspected of ingesting a caustic substance should be triaged to a high priority for prompt evaluation and treatment. This includes prompt evaluation of airway and vital signs as well as immediate cardiac monitoring and intravenous access.
Airway control: Because of the risk of rapidly developing airway edema, immediate assessment of the patient's airway and mental status should be performed and continually monitored. Equipment for endotracheal intubation and cricothyrotomy should be readily available. Gentle orotracheal intubation or fiberoptic-assisted intubation is preferred. Blind nasotracheal intubation should be avoided due to the increased risk of soft-tissue perforation. If possible, it is best to avoid inducing paralysis for intubation because of the risk of anatomical distortion from bleeding and necrosis. If a difficult airway is anticipated, IV ketamine can be used to provide enough sedation to obtain a direct look at the airway. Cricothyrotomy or percutaneous needle cricothyrotomy may be necessary in the presence of extreme tissue friability or significant edema.
Gastric emptying and decontamination: Do not administer emetics because of risks of re-exposure of the vulnerable mucosa to the caustic agent. This may result in further injury or perforation. Gastric lavage by traditional methods using large-bore orogastric Ewald tubes are contraindicated in both acidic and alkaline ingestions because of risk of esophageal perforation and tracheal aspiration of stomach contents. Large-volume liquid acid ingestions may benefit from nasogastric tube (NGT) suction if performed rapidly after ingestion. Pyloric sphincter spasm may prolong contact time of the agent to the gastric mucosa for up to 90 minutes. NGT suction may prevent small intestine exposure. Esophageal perforation is rare. NGT suction may be of particular value following ingestion of zinc chloride, mercuric chloride, or hydrogen fluoride, unless signs of perforation are present. This should be done after consulting with a regional poison control center. Activated charcoal is relatively contraindicated in caustic ingestions because of poor adsorption and endoscopic interference.
Dilution: Dilution may be beneficial for ingestion of solid or granular alkaline material if performed within 30 minutes after ingestion using small volumes of water. Because of the risk of emesis, carefully consider the risks versus benefits of dilution. Do not dilute acids with water because of excessive heat production.
Neutralization: Do not administer a weak acid in alkaline ingestions or a weak alkaline agent in acid ingestions. There is a risk of heat production resulting from this exothermic reaction. In addition, the risk of emesis makes this a hazardous intervention. Intravenous fluids and blood products may be required in the event of significant bleeding, vomiting, or third spacing.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.