Medico

Emerg Med Clin N Am 25 (2007) 249–281

The Approach to the Patient with an Unknown Overdose
Timothy B. Erickson, MD, FACEP, FACMT, FAACT*, Trevonne M. Thompson, MD, Jenny J. Lu, MD
Department of Emergency Medicine, Division of Clinical Toxicology, University of Illinois at Chicago, Toxikon Consortium, Room 471 (M/C 724), 808 South Wood Street, Chicago, IL 60612, USA

Toxic overdose canpresent with various clinical symptoms, including abdominal pain, vomiting, tremor, altered mental status, seizures, cardiac dysrhythmias, and respiratory depression. These may be the only clues to diagnosis when the cause of toxicity is unknown at the time of initial assessment and management. The diagnosis may be complicated by the possibility of a multiple-drug ingestion. The prognosis and clinicalcourse of recovery of a patient poisoned by a specific agent depends largely on the quality of care delivered within the first few hours in the emergency setting. Fortunately, in most instances, the drug or toxin can be quickly identified by a careful history, a directed physical examination, and commonly available laboratory tests. Attempts to identify the poison should never delay life-savingsupportive care, however. Once the patient has been stabilized, the physician needs to consider how to minimize the bioavailability of toxin not yet absorbed, which antidotes (if any) to administer, and if other measures to enhance elimination are necessary [1].

Clinical guidelines Although several published position statements [2–6] and practice guidelines or consensus statements [7] existregarding clinical toxicology diagnosis and management, most of the literature is based on retrospective case series

* Corresponding author. E-mail address: toxboy@uic.edu (T.B. Erickson). 0733-8627/07/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.emc.2007.02.004 emed.theclinics.com

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analysis or isolated case reports with isolated animal orlaboratory research. Well-controlled, randomized, human trials with adequate sample sizes are infrequent and difficult to perform. Regional Poison Control Center data exist and are updated on an annual basis to document changing trends in poisoning epidemiology. This national database is predominantly presented in a retrospective fashion [8]. It is important to note, however, that most severe casesresulting in death never arrive to hospitals (ie, medical examiner cases). Published studies based on poison center data therefore are skewed toward mild to moderate poisonings and may underrepresent a small but important segment of toxic agents [9]. Unfortunately, well-designed forensic toxicology data are limited in the literature. Recently, the poison exposure data of the National HealthInterview Survey and the Toxic Exposure Surveillance System have been compared to identify age-adjusted poisoning episode rates to provide a broader perspective [10].

Epidemiology In the year 2004, more than 2.4 million human exposures to toxins were reported to the American Association of Poison Control Centers [8]. More than 75% were reported from the home and 15% from a health care facility. Twothirds of the reported exposures involved pediatric patients less than 20 years of age. The leading agents were cleaning substances, followed by analgesics and cosmetics/personal care products [8]. There were 1183 reported poisoning fatalities with children less than 6 years of age representing only 2% of these deaths. The leading fatal agents were analgesics, antidepressants, cardiovasculardrugs, stimulants, and street drugs [8]. Toxicokinetics
What is it that is not a poison? All things are poison and nothing is without poison. Solely, the dose determines that a thing is not a poison. dParacelsus (1493–1541), the Renaissance Father of Toxicology, in his Third Defense [11]

As described by the Renaissance toxicologist Paracelsus, any substance should be considered a potential poison...