Toxicology represent a clinical dilemma for clinicians worldwide and impart a diagnostic challenge, particularly in the intensive care unit (ICU) setting. A poisoned patient typically cannot provide a history; therefore, an adequate diagnosis relies on laboratory data and an astute clinician identifying specific toxidromes and having a high index of suspicion.
Poisoning is the leading cause of injury-related death in the United States.1 In 2015, 47% of exposure cases involved children younger than 6 years of age, but as in previous years, many of the more serious cases occurred among adolescents and adults. A total of 57% of human exposures involved medications or pharmaceuticals. Other exposures were to household products, plants, mushrooms, pesticides, animal bites and stings, carbon monoxide, and many other types of nonpharmaceutical substances.2 The majority of exposures were ingestions or aspirations in 79% (Fig. 30-1) and were unintentional (Fig. 30-2). The categories of substances or toxins with the largest number of exposures in all ages included analgesics (11.1%), cleaning substances (7.6%), and sedative–hypnotics (5.8%).2
FIGURE 30-1
Routes of exposure for a total of 2,279,087 reported exposure cases. (Data from Gummin DD, Mowry JB, Spyker DA, et al. (2017) 2016 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 34th Annual Report, Clin Toxicol, 55(10), 1072-1254.)
Absorption: The degree of absorption of medications is highly dependent on the environment at the site of administration. Shock states decrease perfusion and shunt blood to the vital organs reduce systemic absorption of drugs from the intestines and intramuscular and subcutaneous tissues.3 Intestinal atrophy can begin after only 3 days of starvation and is not prevented by parenteral nutrition (see Figure 30-3).4
Distribution: Sepsis, shock, burn injury, pancreatitis, and alterations in plasma protein binding are just a few examples of disease entities influencing the volume of distribution (Vd). Alternatively, fluid resuscitation, as frequently necessary in critically ill patients, will also lead to increased Vd.
Metabolism: Drug metabolism occurs predominantly in the liver and is driven mainly by the cytochrome P450 enzyme system. Critical illness affects metabolic activity by alterations in plasma protein concentration, hepatic enzymatic activity, and blood flow. Many drugs used in critically ill patients may either induce or inhibit the activity of the various isoenzymes included in the cytochrome P450 complex.
Elimination: Augmented renal clearance can be driven by sepsis, burn injury, or use of inotropic agents. On the other hand, acute kidney injury may complicate clearance of drugs, necessitating renal replacement therapy or dialysis.5
The diagnosis is often clinical, and it is common that multiple toxicities occur at the same time.6-10 (Tables 30-1, 30-2, 30-3, 30-4)7,11-16 Treatment is not necessarily dependent on confirmation of the diagnosis because it may delay an opportunity to prevent further damage.
| Toxidrome | Clinical Characteristics |
|---|---|
| Anticholinergic (antihistamines, atropine, baclofen, benztropine, tricyclic antidepressants, phenothiazine, scopolamine) | Fever, dry skin, flushing, mydriasis, ileus, urinary retention, tachycardia, hypertension, psychosis, myclonus, seizures, coma |
| Cholinergic (carbamate, organophosphates, physostigmine, pilocarpine) | Salivation, lacrimation, urination, diarrhea, emesis wheezing, diaphoresis, bradycardia, miosis |
| β adrenergic (albuterol, theophylline) | Tachycardia, hypotension, tremor |
| α adrenergics (phenylephrine, phenylpropanolamine) | Hypertension, bradycardia, mydriasis |
| β and α adrenergics (amphetamines, cocaine, ephedrine, phencyclidine, pseudoephedrine) | Hypertension, tachycardia, mydriasis, diaphoresis, dry mucous membranes |
| Hallucinogenic (amphetamines, cocaine, cannabinoids, lysergic acid diethylamide, pnecyclidine) | Hallucinations, psychosis, panic, fever, mydriasis, hyperthermia, synesthesia |
| Serotinin (fluoxetine, meperidine, paraoxetine, sertraline, trazodine, clomipramine) | Irritiabilitity, hyperreflexia, flushing, diarrhea, diaphoresis, fever, trismus, tremor, myoclonus |
| Extrapyramidal (haloperidol, phenothiazines, resperidone olanzapine) | Rigidity, trismus, hyperreflexia, choreoasthetosis, opisthothonas |
| Narcotics (opiates, propoxyphene) | Miosis, altered metal status, hypotension, hypothermia, decreased bowel sounds, shallow breaths |
| Plant Name | Clinical Characteristics |
|---|---|
| Jimsonweed, angel’s trumpet, deadly nightshade, mandrake, black henbane | Anticholinergic symptoms including agitation, hallucinations, hyperthermia, tachycardia, rhabodmyolysis, renal failure |
| Tobacco, betel nut, hemlock | Paresthesias, nausea, vomiting, seizures, autonomic instability bronchospasm, bronchorrhea, salivation |
| Morning glory and Hawaiian baby woodrose | Hallucinations, agitation, tachycardia, rhabdomyolysis |
| Water hemlocks / dropwarts from genera Cicuta and Oenanthe | Vomiting, seizures, rhadomyolysis |
| Strychnine | Hyperreflexia, rigidity, opisthotonus, rhabomyolysis, acute renal injury, respiratory failure |
| Foxglove, common oleander, yellow oleander, lily of the valley | Vomiting, bradycardia, AV blocks, increase automaticity |
| Monkshood, genus Veratrum, Rhododendron | Sinus bradycardia, heart blocks, paraesthesias, vomiting |
| Pyrrolizidine alkaloids like groundsel and comfrey | Liver failure |
| Ackee fruit | Hyperammonia, hepatic microvascular steatosis, vomiting, abdominal pain, hypotonia, seizures, coma |
| Amanita phalloides, Lepiota species, and Galerina species | Gastroenteritis, encephalopathy, liver failure |
| Gyromitrin | Gastroenteritis, hemolytic anemia, methemoglobinemia |
| Amanita muscaria, Amanita pantherina | Nausea, vomiting, CNS abnormalities such as depression, stimulation, seizures, ataxia |
| Animal | Clinical Characteristics |
|---|---|
| Scorpion (Centruroides sculpturatus) | Pain and parathesias that can lead to cranial nerve palsies including loss of pharyngeal tone |
| Brown Recluse Spider (Loxosceles reclusa) | Erythema to large ulceration on site of bite that can progress to necrosis resulting in eschar, hemolytic anemia, diarrhea |
| Black Widow (Latrodectus mactans) | Painful target like lesion, intermittent muscle spasms, diaphoresis (local or diffuse), fever, priapism, acute cardiomyopathy |
| Pit vipers | Pain and edema with formation of hemorrhagic bullae around bite stie, tachycardia, vomiting, paresthesia, fasciculations, diarrhea, shock |
| Stingrays (Chondrichthyes) | Hemorrhage, pain, edema, wound necrosis |
| Stone fish and Lion Fish (Scorpaenidae family) | Hemorrhage, pain, edema, wound necrosis |
| Portugese-man-of-war (Physalia physalis) | Pain, edema, redness, wound necrosis, delayed hypersensitivity reaction, shock |
| Sea sponge | Wound necrosis |
| Sea urchin | Pain, arthritis, nausea, vomiting, muscular paralysis |
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