Care of the Poisoned Patient

Toxicologic History and Physical

Oftentimes, the poisoned patient may be altered, obtunded, or uncooperative with the examiner. This leaves the history limited to that which can be gleaned from witnesses, such as paramedics or family, and the information generated from physical examination findings over which the patient does not have conscious control.

Historical information should be pulled from all available sources. A family member or friend may offer insight into the circumstances behind the patient’s exposure (e.g., intentional or accidental). Information regarding what medications or substances were available to the patient, and the timing of ingestion also is important. Paramedics should bring in all medication bottles present at the scene, not just the patient’s prescribed medications or alleged ingestion; if they do not, someone should be sent to the patient’s dwelling to retrieve them. Frequently, confusion as to what exactly was ingested can occur (e.g., ibuprofen mistaken for aspirin or acetaminophen) and this can lead a provider down the wrong path. A patient attempting suicide may intentionally mislead the ED staff, or medications may have been stored in mislabeled containers. Other sources of potentially useful information include state controlled-substance registries, pharmacy records, and previous medical records. Accessing the patient’s text-messaging history also may be helpful, if the patient consents to this or if friends and family provide this collateral information of their own accord.

For chemical exposures in either the home or workplace, avoid exposure to other individuals in the ED. Proper identification of the substance is important to initiate care and obtain product safety information, such as a Material Safety Data Sheet. Consequently, one could consider taking a picture of the label including any precise chemical numbers; if a substance is brought to the ED, take appropriate steps to avoid further exposure, such as sealing in an airtight container.

Poisoned patients are frequently unwilling or unable to participate in an interactive physical examination. The toxicologic physical examination, therefore, rests upon observing factors that do not require cooperation to elicit. Many ingested substances can cause derangement of the pulse, respiratory rate, as well as blood pressure. Rapid and accurate recording of the patient’s vital signs, including pulse oximetry and a rectal core temperature, should be done and repeated at appropriate intervals depending on the suspected toxin. Patients with hemodynamic instability or obtundation should be considered for continuous monitoring, at least initially until stabilized. The overall level of consciousness, pupillary size, and presence or absence of seizure activity may suggest a particular agent ( Boxes 135.1 and 135.2 ). Examination of the skin and mucous membranes with particular attention to discoloration and level of moisture may suggest poisoning by any of several agents ( Box 135.3 ); it may also reveal evidence of injection drug abuse, such as “track marks” or ulcerations from “skin popping.” A careful neurologic examination focusing on the level of muscle tone, clonus, or hyperreflexia can assist in the diagnosis of serotonin syndrome or neuroleptic malignant syndrome (NMS). Certain intoxicants may have particular odors associated with them; the presence of such an odor ought to alert the clinician to the possibility of poisoning by one of these agents ( Table 135.1 ); however, the absence of a characteristic smell does not exclude it.

Toxidromes

Toxidromes are constellations of signs and symptoms based on autonomic and neurochemical processes that can suggest a particular class of exposure and direct management and therapy. The five traditionally described entities include the sympathomimetic, anticholinergic (antimuscarinic), cholinergic, sedative/hypnotic, and opioid toxidromes. In addition, withdrawal disorders, serotonin syndrome, and NMS have been well described.