Poisoning - General Principles, Types, Diagnosis, and Management

What Is Poisoning?

Any substance that is detrimental to the body's health is considered a poison. There are numerous varieties of poison. Products that are found around the house may contain poisonous toxins. Not taking medications as prescribed can have negative effects. There are numerous ways to come into contact with poison. It could be ingested, inhaled, or absorbed through the skin. Both accidents and deliberate actions can result in poisoning.

What Are the General Principles of Poisoning?

Most poisonings are dose-dependent, meaning the severity of toxicity is determined by the concentration of the substance and the duration of exposure. Toxicity can occur when excessive amounts of typically non-toxic substances are encountered. Additionally, some substances are inherently poisonous regardless of the dose. It is important to differentiate poisoning from hypersensitivity and idiosyncratic reactions, which are unpredictable and unrelated to the dose, as well as from intolerance, which refers to a toxic response to an otherwise non-toxic dose of a substance.

Poisoning commonly occurs through ingestion, but it can also result from injection, inhalation, or contact with body surfaces such as the skin, eyes, or mucous membranes. While many non-food substances ingested are generally non-toxic, virtually any substance can become toxic if ingested in excessive quantities.

Accidental poisoning is frequently observed in young children who, despite unpleasant tastes and odors, are naturally curious and may ingest various items. Typically, these cases involve a single substance. Poisoning is also prevalent among older children, adolescents, and adults who attempt suicide, often involving multiple drugs, including alcohol, Acetaminophen, and other over-the-counter (OTC) medications. Older individuals may experience accidental poisoning due to factors such as confusion, poor eyesight, mental impairment, or the simultaneous use of multiple medications prescribed by different physicians.

Occasionally, individuals may be intentionally poisoned by others with the intent to harm or incapacitate them, such as in cases of robbery or sexual assault. Drugs used for incapacitation (for example, Scopolamine, Benzodiazepines, Gamma-hydroxybutyrate) tend to possess sedative or amnestic properties or both.

Following exposure, ingestion, and absorption, most poisons undergo metabolism, pass through the gastrointestinal (GI) tract, or are excreted. In some cases, tablets (for example, Aspirin, iron, enteric-coated drugs) can form large concretions (bezoars) within the GI tract, where they tend to remain, continue to be absorbed, and cause toxicity.

What Are the Types, Signs, and Symptoms of Poisoning?

Types of poisoning:

• Ingested poisons.

• Inhaled poisons.

• Contact poisons (poisons that can be absorbed through the skin).

• Ocular poisons (poisons that can affect the eyes).

Symptoms and signs of poisoning can vary depending on the specific substance involved. Furthermore, even when patients are poisoned with the same substance, their symptoms may differ significantly. However, there are six commonly observed clusters of symptoms, known as toxic syndromes or toxidromes, which can suggest the involvement of particular classes of substances. It is important to note that patients who have ingested multiple substances are less likely to exhibit symptoms that are characteristic of a single substance.

The onset of symptoms typically occurs shortly after exposure, although in some cases, there may be a delay. This delay can be attributed to situations where the toxic effects are caused by metabolites rather than the parent substance itself (for example, methanol, ethylene glycol, hepatotoxins). Acute liver failure resulting from the ingestion of hepatotoxins (for example, Acetaminophen, iron, Amanita phalloides mushrooms) may manifest one to a few days after ingestion. Symptoms associated with metals or hydrocarbon solvents generally appear only after chronic exposure to the toxin.

• Ingested Toxins: Toxins that are ingested and absorbed generally lead to systemic symptoms. Caustic substances and corrosive liquids primarily damage the mucous membranes of the gastrointestinal (GI) tract, resulting in stomatitis, enteritis, or perforation. Certain toxins (for example, alcohol, hydrocarbons) can cause distinctive breath odors. Direct contact of the skin with toxins may cause various acute cutaneous symptoms such as rashes, pain, or blistering, while chronic exposure can lead to dermatitis.

• Inhaled Toxins: They tend to cause symptoms of upper airway injury if they are water-soluble (for example, chlorine, ammonia) and symptoms of lower airway injury and noncardiogenic pulmonary edema if they are less water-soluble (for example, phosgene). Inhalation of gasses like carbon monoxide, cyanide, or hydrogen sulfide can result in organ ischemia or cardiac and respiratory arrest.

• Eye Exposure: Eye exposure to toxins in solid, liquid, or vapor form may result in damage to the cornea, sclera, and lens, leading to symptoms such as eye pain, redness, and vision loss.

Certain substances (for example, Cocaine, Phencyclidine, and Amphetamine) can induce severe agitation, which may subsequently cause hyperthermia, acidosis, and rhabdomyolysis (muscle tissue breakdown).

How Poisoning Is Diagnosed?

The most common indicators of poisoning include respiratory or cardiovascular depression, impaired consciousness, dehydration resulting from diarrhea or vomiting, convulsions, hypothermia (significant drop in body temperature), arrhythmia (irregular heartbeat), and coma. Therefore, a diagnosis of poisoning is primarily based on the exhibited symptoms. The diagnostic process considers the following factors:

• History: Obtaining and documenting information such as the name and type of drug, timing of drug ingestion, concurrent use of other substances like alcohol, method of ingestion, and quantity of the drug is crucial. This information provides insights into the patient's clinical condition, stability, and drug metabolism.

• Physical Examination: A comprehensive physical examination involves assessing breathing, airway patency, circulation, mental state, pupil size, temperature, blood pressure, blood glucose levels, pulse, electrocardiogram (ECG) findings, muscle tone, and reflexes. Additionally, any evidence, such as a suicide note or containers of poisons, is recorded. The nature of the poisoning is evaluated based on the source (homicidal, suicidal, accidental), and appropriate authorities, including forensic toxicologists and law enforcement, are notified when necessary. Depressed states may be associated with antipsychotics, antidepressants, antiarrhythmics (drugs to treat problems with heart rhythm), adrenergic blockers (drugs for hypertension), carbamates (insecticides), narcotics, sedatives, and hypnotics, whereas agitated states may be caused by caffeine, cocaine, ergot alkaloids (drugs to treat headaches), antihistamines, and antiparkinsonian drugs.

• Laboratory Evaluation: Laboratory tests are conducted to measure oxygen levels in the blood, arterial blood gas analysis, plasma osmolarity, and oxygen binding capacity to hemoglobin, using appropriate techniques.

• Toxicological Testing: Toxicological testing provides direct evidence of the presence of toxins in the body. However, before initiating such tests, the patient should receive primary supportive measures to stabilize their condition. Toxicological screening assists in determining the appropriate antidote, reducing further absorption of the poison, and guiding subsequent management.

How Is Poisoning Managed?

Supportive Care: Supportive care is an essential aspect of poisoning management, and it involves various interventions to stabilize and assist patients. The following approaches are commonly employed:

• Activated Charcoal for Serious Oral Poisoning: Activated charcoal is recommended, particularly when the ingestion involves multiple or unidentified substances. It poses minimal risk, except in cases where vomiting and aspiration are likely. Activated charcoal is administered as soon as possible since it can adsorb many toxins due to its molecular configuration and large surface area. Multiple doses may be necessary for substances that undergo enterohepatic recirculation or are in sustained-release formulations. However, it is ineffective for caustics, alcohols, and certain ions (for example, Cyanide, iron, other metals, and Lithium). The recommended dose of activated charcoal is typically five to ten times that of the suspected toxin ingested. In cases where the exact amount of toxin ingested is unknown, the usual dose is 1 to 2 grams per kilogram of body weight. The administration is in the form of a slurry in water or soft drinks, but it may be unpalatable and induce vomiting in some patients. In certain situations, the use of a gastric tube for administration may be considered, weighing the potential benefits against the risks. It is generally recommended to administer activated charcoal without sorbitol or other cathartics, as they offer no clear benefits and can lead to dehydration and electrolyte imbalances.

• Occasional Use of Specific Antidotes or Dialysis: Specific antidotes or dialysis may be required in select cases. Antidotes are employed for poisoning caused by specific substances, while dialysis is used for the removal of certain toxins from the bloodstream. Examples of toxins that may necessitate dialysis or specific antidote therapy include Ethylene glycol, Lithium, Methanol, Salicylates, and Theophylline. However, the effectiveness of these therapies may vary depending on factors such as the nature of the poison and the patient's clinical condition. The decision to use specific antidotes or dialysis is typically based on both laboratory values and the patient's overall status.

• Only Rare Use of Gastric Emptying: Routine gastric emptying is no longer recommended as a standard treatment approach for poisoning. Gastric emptying should only be considered if it can be performed within one hour of life-threatening ingestion. However, many poisonings may not present early enough, and it may be challenging to determine whether a poisoning is life-threatening. As a result, gastric emptying is rarely indicated and is contraindicated in cases involving caustic substances. Gastric lavage is the preferred method if gastric emptying is deemed necessary, but it can lead to complications such as epistaxis, aspiration, or injury to the oropharynx or esophagus. Whole-bowel irrigation may be considered in specific situations, such as poisonings involving sustained-release preparations or non-absorbable substances like heavy metals. It involves flushing the gastrointestinal tract with a specially prepared solution of polyethylene glycol and electrolytes to accelerate the transit of pills or tablets.

• Ongoing Supportive Measures: Additional supportive measures are crucial in managing various symptoms and complications associated with poisoning. These measures include addressing agitation, sedation, coma, cerebral edema, hypertension, arrhythmias (irregular heartbeat), renal failure, and hypoglycemia, among others. The standard supportive measures employed for these conditions should be followed. However, some cases of drug-induced hypotension and arrhythmias may not respond to usual drug treatments. In such situations, alternative approaches like Dopamine, Epinephrine, other vasopressors, intra-aortic balloon pump, or extracorporeal circulatory support may be considered for refractory hypotension. Refractory arrhythmias may necessitate cardiac pacing, and torsades de pointes can be managed using Magnesium sulfate, overdrive pacing, or a titrated Isoproterenol infusion. Seizures should be initially treated with Benzodiazepines, while severe agitation may require high-dose Benzodiazepines, other potent sedatives (for example, Propofol), or even induction of paralysis and mechanical ventilation in extreme cases. Hyperthermia should be managed through aggressive sedation and physical cooling measures rather than relying solely on antipyretics. Organ failure, if it occurs, may ultimately require kidney or liver transplantation.

• Hospital Admission: Hospital admission is generally warranted in cases of altered consciousness, persistently abnormal vital signs, or anticipated delayed toxicity. For instance, admission should be considered for patients who have ingested sustained-release preparations, particularly those involving drugs with potentially severe effects, such as cardiovascular drugs. If there are no other indications for admission, laboratory test results are normal, and symptoms have resolved after observation for four to six hours, most patients can be safely discharged. However, in cases of intentional ingestion, a psychiatric evaluation should be conducted for patients before discharge.

How to Prevent Poisoning?

In the United States, the widespread use of child-resistant containers with safety caps has significantly reduced the number of poisoning deaths in children under the age of five. Implementing measures such as limiting the quantity of over-the-counter (OTC) analgesics in a single container and eliminating confusing and redundant formulations has proven effective in reducing the severity of poisonings, particularly those involving Acetaminophen, Aspirin, or Ibuprofen. Additional preventive measures include:

• Clearly label household products and prescription drugs to enhance awareness of their potential hazards.

• Storing drugs and toxic substances in cabinets that are securely locked and inaccessible to children minimizes the risk of accidental ingestion.

• Promptly disposing of expired drugs by mixing them with cat litter or another non-appealing substance and placing them in a trash container that is out of reach for children.

• Using carbon monoxide detectors to detect and prevent exposure to this odorless and potentially deadly gas.

• Minimizing the prescription of opioids and prioritizing nonopioid treatments whenever possible to reduce the risk of opioid-related poisonings and misuse.

• Implementing public education campaigns to promote the storage of substances in their original containers, discouraging the transfer of hazardous materials to alternative containers (for example, placing insecticides in drink bottles).

• Incorporating imprint identifications on solid drugs to prevent confusion and errors among patients, pharmacists, and healthcare practitioners.

Conclusion

In conclusion, understanding the general principles, types, diagnosis, and management of poisoning is essential for prompt and effective intervention. Poisoning can present a significant risk to individuals of all ages, necessitating preventative measures such as child-resistant containers, clear labeling, secure storage, and proper disposal of toxic substances. Timely diagnosis and appropriate management, including supportive care, specific antidotes, and, in some cases, dialysis or hemoperfusion is crucial in mitigating the harmful effects of poisoning. Public education and awareness campaigns play a vital role in preventing poisonings and promoting safe practices. By implementing these strategies and staying informed, people can work towards reducing the incidence and severity of poisonings, safeguarding the health and well-being of individuals in the communities.