John J. Graykoski Poison is defined as a chemical capable of causing illness that enters the body through ingestion, transdermal absorption, intravenous administration, radiation, inhalation, or venom transmitted by stings or bites. Poisonings can be accidental (e.g., contact with concentrated chemicals or industrial agents, taking the wrong medication) or intentional (e.g., illicit drug use). Poisonings can also be industrial (e.g., spraying field workers with pesticides) or an act of war or terrorism (e.g., chemical weapons). By any means or by any cause, poisoning represents a life-threatening situation until proven otherwise. It will always be best treated in an emergency department that has decontamination and isolation resources (if required), diagnostic laboratory services immediately available, and intensive care monitoring. The United States has a system of 57 regional poison control centers that upload all contacts in real time, providing a rapid threat assessment for clusters of poisoning as well as a major database for understanding of poisoning trends. In 2013, more than 3,060,122 calls were fielded by the centers; 48% of the cases involved children younger than 6 years.1 Eighty percent of exposures were determined to be accidental, whereas suicide was suspected in 10.5%. Therapeutic errors and unintentional misuse represented 18.1% of cases1. A total of 2477 fatalities occurred1. Of particular concern is the fact that drug overdose is the second leading cause of injury-related death in this country.2 The data from the American Association of Poison Control Centers represent an important window into the substances involved in poisoning as well as trends analyzed yearly since 1983. The pathophysiologic process depends on the poisonous substance and on the route, duration, and amount of exposure. The patient’s underlying physical condition and initial first aid measures will also affect the impact of the toxin. The presentation of poisoning can have differing signs and symptoms depending on the patient and type of poisoning. In an ideal scenario, the patient or patient’s family can provide accurate information about the situation. However, in many cases the poisoning is assumed based on circumstantial findings, such as a sleeping person who will not wake and empty acetaminophen bottles found in the room. The provider should suspect poisoning in patients with unexplained and sudden respiratory wheezing or dyspnea, acute agitation, somnolence that is progressive, hallucinations or delusions, areas of erythema or rash that appear suddenly, acute onset of epigastric pain, vomiting, diarrhea, hypertension and hyperthermia, and sudden and unexplained loss of consciousness. The provider should be particularly alert to situations in which a number of people show similar symptoms within a short time, especially if they were in a common area. A low threshold of suspicion for a common source of poisoning requires action to prevent additional casualties—for example, several people with vomiting and diarrhea who report having eaten potato salad at the volunteer fire department picnic, or a group of postal workers who develop worsening cough and shortness of breath after coming in contact with a package. An early call to the local health department is indicated to report such cases so that further investigation may be implemented. In cases involving exposure of a group of people to a toxic substance, such as the release of refrigerant in cold processing plants, the fire department should be called to the scene before transport to a health facility so that appropriate decontamination can occur. The clinical evaluation begins with a detailed history. Special attempts are made to obtain information from family and first responders. Attempts must be made to recover medication bottles and over-the-counter medicines. Recovery of any chemicals used at the site of overdose or exposure is important. Material Safety Data Sheets should be available at any site where chemicals are in use. These provides vital information on the chemicals’ composition and phone numbers for additional information. Previous exposures, medical conditions including chronic illnesses, and current medications should be obtained. Psychiatric issues will be important in assessment of stress reaction to the poisoning as well as previous suicide attempts, mental health interventions, and hospitalizations. The physical examination should assess mood and emotions. Issues of depression, anxiety, sleep disturbance, substance abuse, and hallucinatory or delusional processes must be explored. An assessment of suicidal risk should be undertaken. The neurologic examination should note pupillary reaction, nystagmus, deep tendon reflexes, gait, station, Romberg test result, and pronator drift. The Glasgow Coma Scale score is recorded on arrival and monitored for change (see Table 32-1). Skin temperature and color are noted. The body must be exposed, looking for rashes, burns or irritations, bruising, and needle marks suggestive of injection drug use. The provider must observe for areas of discoloration or frank necrosis as well as blistering. Cardiovascular considerations include tachycardia, bradycardia, and peripheral circulation. The respiratory system must be evaluated for good air movement and oxygen saturation; carbon monoxide and carbon dioxide should be tested at bedside; and secretions, color, retractions, rales, and wheezing should be noted. Gastrointestinal examination includes observation of vomitus and feces, watching especially for bleeding. Guaiac testing of stool and vomitus should be done. Bowel sounds must be noted and their character reported. In addition to vital signs and physical findings, laboratory values can be an important aspect of the diagnostic evaluation and aid in management. Diagnostic tests should be dictated by the toxicologic exposure. Some substances, including alcohol, aspirin, acetaminophen, illicit drugs, iron, lead, mercury, carboxyhemoglobin, and ethylene glycol, can be measured directly. Assessment of arterial blood gases, the anion gap, the osmolar gap, and the oxygen saturation gap may provide additional information. Other laboratory studies are helpful in assessing end-organ involvement. These should include electrolyte values; glucose, blood urea nitrogen (BUN), and creatinine concentrations; and liver function tests. Urine screens may be indicated if cocaine, opiates, or marijuana is suspected. A pregnancy test should be obtained, if indicated. An electrocardiogram (ECG) is necessary with specific poisons, and assessment will need to be repeated in some instances.3 Further evaluation is indicated if abnormalities such as acidosis and hypoxia are discovered.
Poisoning
Definition
Epidemiology
Pathophysiology
Clinical Presentation
Physical Examination
Diagnostics
Poisoning
Chapter 34
