Chapter 32. Clinical Toxicology

• Clinical toxicology encompasses the expertise in the specialties of medical toxicology, applied toxicology, and clinical poison information.
• Important components of the initial clinical encounter with a poisoned patient include stabilization of the patient, clinical evaluation (history, physical, laboratory, and radiology), prevention of further toxin absorption, enhancement of toxin elimination, administration of antidote, and supportive care with clinical follow-up.

The following general steps represent important components of the initial clinical encounter with a poisoned patient:

1. stabilization of the patient;

2. clinical evaluation (history, physical, laboratory, and radiology);

3. prevention of further toxin absorption;

4. enhancement of toxin elimination;

5. administration of antidote;

6. supportive care and clinical follow-up.

Clinical Stabilization

The first priority in the treatment of the poisoned patient is stabilization. Assessment of the vital signs and the effectiveness of respiration and circulation are the initial concerns. Some toxins or drugs can cause seizures early in the course of presentation. The steps and clinical procedures incorporated to stabilize a critically ill, poisoned patient are numerous and include, if appropriate, support of ventilation, circulation, and oxygenation. In critically ill patients, sometimes treatment interventions must be initiated before a patient is truly stable.

Clinical History in the Poisoned Patient

The primary goal of taking a medical history in poisoned patients is to determine, if possible, the substance ingested or the substance to which the patient has been exposed as well as the extent and time of exposure. In the setting of a suicide attempt, patients may not provide any history or may give incorrect information so as to increase the possibility that they will successfully bring harm to themselves. Information sources commonly employed in this setting include family members, emergency medical technicians who were at the scene, a pharmacist who can sometimes provide a listing of prescriptions recently filled, or an employer who can disclose what chemicals are available in the work environment.

In estimating the level of exposure to the poison, one generally should maximize the possible dose received. That is, one should assume that the entire prescription bottle contents were ingested, that the entire bottle of liquid was consumed, or that the highest possible concentration of airborne contaminant was present in the case of a patient poisoned by inhalation.

With an estimate of dose, the toxicologist can refer to various information sources to determine what the range of expected clinical effects might be from the exposure. The estimation of expected toxicity greatly assists with the triage of poisoned patients. Estimating the timing of the exposure to the poison is frequently the most difficult aspect of the clinical history in the setting of treatment of the poisoned patient.

Taking an accurate history in the poisoned patient can be challenging and in some cases unsuccessful. When the history is unobtainable, the clinical toxicologist is left without a clear picture of the exposure history. In this ...