Poisoning

Department of the Navy
Bureau of Medicine and Surgery

The management of the poisoned, intoxicated, or overdosed patient must be organized and deliberate. Preventing complications and avoiding iatrogenic injury are at least as important as identifying the toxin and providing specific antidotal therapy. The poisoning emergencies you face may range from acute ethanol intoxication to hazardous materials exposures and smoke inhalation, to ingestion of prescription or over the counter (OTC) medication in suicidal attempts, to accidental oral or dermal exposures in the pediatric population. While it is beyond the scope of this chapter to discuss in detail the presentation and management of specific toxins, some general principles guide the treatment of any poisoned patient. The GMO should have a reference text and the telephone number of the regional poison control center readily available for specific information.

The history obtained from a poisoned patient is often inaccurate or incomplete, but the following information should still be sought from any source available.

Physical Exam

• Complete vital signs noting any trends.

• Mental status.

• Focused exam: pulmonary, cardiovascular, abdomen, neurological systems as well as evidence of trauma and abdominal exam, (useful in identifying toxidromes).

Request an electrocardiogram (ECG) for patients with an abnormal or irregular pulse or who have ingested a cardiotoxic drug. A flat plate and upright abdominal x-ray (KUB) may be helpful in identifying radiopaque substances such as heavy metals or enteric coated tablets.

• Electrolytes, glucose, BUN/creatinine.

• Arterial blood gas (ABG).

• Aspirin, acetaminophen, ETOH levels.

• CBC.

• Qualitative urine or serum drug screens seldom alter treatment or immediate disposition, but may be useful for later documentation of psychiatric evaluation.

• Qualitative levels of specific drug toxins are useful in the following limited number of agents: acetaminophen, aspirin, ethanol, methanol, ethylene glycol, iron, digoxin, theophylline, lithium, and anticonvulsants.

Five principles of treatment should be considered in the management of every poisoned patient. They may need to occur simultaneously in some patients while in other patients some of them may be inappropriate or even dangerous and have no role.

ABC's (Airway-Breathing-Circulation).
Ensuring and protecting an adequate airway and maintaining effective ventilation are paramount in managing the poisoned patient. Many agents produce sedation, leading to loss of airway protection and the risk of vomiting and aspiration. Maintaining adequate perfusion of the brain, heart, and kidneys can usually be accomplished with intravenous fluids and pressors such as dopamine. In the patient with altered mental status, the following drugs are given.

• Oxygen

• Narcan (naloxone) 2mg 1V push

• Thiamine 100mg IV push

• D50 1 AMP IV push (or check dextrostick to R/O hypoglycemia)

Decontamination.
The first goal in managing the adequately resuscitated poisoned patient is minimizing further exposure to the toxin by decontamination. For dermal exposures, decontamination of the skin should be accomplished quickly by removing all contaminated clothing and washing the skin thoroughly with soap and water while protecting care providers from secondary exposure. Ocular decontamination is accomplished by copious irrigation using tap water or normal saline. Gastrointestinal decontamination may be accomplished by the following methods:

Note: The single most effective method to decontaminate the GI tract is with the use of activated charcoal.

• Emesis
  Syrup of ipecac has a very limited role currently because of the risk of aspiration in the patient whose mental status may decline, and because it is less effective than activated charcoal alone. It is contraindicated in caustic ingestions or in patients with an altered mental status or in the ingestion of any agent which may lead to seizures or coma. Complications include aspiration, Mallory Weiss tear, esophageal tears, and electrolyte imbalance.

• Gastric Lavage
  May be more effective than emesis, but is of limited use if more than an hour has passed from the ingestion. Lavage is performed using a large (36F) orogastric tube with the patient in the left lateral decubitus position. Use saline in small aliquots of 100-200cc lavage with a total of 2 liters or until the return is clear

• Adsorbent (activated charcoal)
  Administration of 1 to 2 gm/kg of activated charcoal orally (PO) or via a nasogastric (NG) tube is adequate gut decontamination for the majority of patients. Activated charcoal does not bind iron, heavy metals, hydrocarbons, or alcohols well, but should be given in the event other co-ingestants are present.

• Whole-bowel Irrigation.
  Using Go-Lytely, 2L/hour PO or via a nasogastric tube for 5-6 hours. This may be indicated after ingestion of substances poorly bound to charcoal (iron, lithium), extended-release preparations (Theodur, calcium channel blockers), foreign bodies (button batteries), and drug packets (heroin, cocaine, condoms).

Aggressive Supportive Care.
When combined with resuscitation and decontamination, aggressive supportive care to prevent and manage complication is key to the successful management of the vast majority of poisoning exposures. Therefore, early consultation and possible transfer is generally indicated due to limited resources available to most GMOs.

Enhanced Elimination
Techniques for removing toxins after they have already been absorbed into the systemic circulation are seldom indicated or applicable, but at times they may be central to the management of certain toxins.

• Alkaline diuresis (salicylates): alkalinize the urine to a pH of 8.0 by administering normal saline with 1-2amps of bicarbonate per liter and adequate potassium replacement.

• Repeat-dose activated charcoal (theophylline, phenobarbital, carbamazepine): 0.5gm/kg PO or NG every 4 hours to produce gut dialysis and interrupt enterohepatic recirculation.

• Hemodialysis (salicylates, methanol, ethylene glycol, lithium): consult with a toxicologist or nephrologist for recommendations.

Specific Antidotes
Appropriately administered antidotes may prevent further complications, morbidity and mortality, but most antidotes have potential adverse effects and may not be indicated in a given patient. Seek advice when considering the use of an antidote. The following list includes some of the more useful antidotes.

• Acetaminophen
  Mucomyst 140mg/kg 1st dose, then 70mg/kg every 4 hours for 17 additional doses.

• Tricyclic antidepressants
  Sodium bicarbonate 1 to 2 amps IV push, then infusion of bicarbonate in D5W to keep the arterial pH 7.50.

• Isoniazid (INH)
  Pyridoxine (vitamin B6) same amount as INH ingested if known; if unknown, give 5gm IV.

• Narcotics
  Naloxone (Narcan) 2mg IV push (some narcotics may require larger doses or continuous infusions).

• Cyanide
  Lilly Cyanide Antidote Kit (amyl nitrate pearls, sodium nitrite, sodium thiosulfate vials-see insert for directions).

• Carbon Monoxide
  100 percent oxygen followed by hyperbaric oxygen.

• Iron
  Deferoxamine 10 to 15mg/kg/hr.

• Beta blockers
  Glucagon 1 to 5mg IV push, repeat as necessary.

• Anticholinegics
  Physostigmine 1 to 2mg IV push - (use only for dysrhythmias with hypotension, intractable seizures, or coma with respiratory compromise; intubation should be performed first; contraindicated in TCA overdose).

• Insecticides/organophosphates
  Atropine IV (may require large doses), followed by Pralidoxime (2- PAM )

• Benzodiazepines
  Flumazenil (Romazicon) 0.5 to1mg increments IV, total dose rarely to exceed 3mg (do not use if coingestion of an epileptogenic drug).

• Oral hypoglycemics
  For intractable hypoglycemia, not responsive to IV glucose, use diazoxide 300mg IVPB over 30 minutes.

• Calcium Channel Blockers:
  Calcium chloride, 1 to 2amps (100 to 200mg) over 2 to 5 minutes. May repeat to effect, and may need continuous infusion. Consider atropine 1 to 2 mg or glucagon 3 to 10mg for A-V block or profound bradycardia. May require pressors and pacing.

• Cocaine
  Control seizures with benzodiazepines, control hypertension with lopressor and nitroprusside. Caution: the use of beta blockade alone increases mortality due to unopposed alpha effects.

Disposition
If after evaluation and treatment, a patient is asymptomatic, has a normal mental status exam, normal pertinent labs, and normal vital signs (including pulse rate), the patient is medically cleared, the patient should then be referred to psychiatry. However, some drugs or agents, i.e., acetaminophen, iron, and mushrooms, have a latent period during which the patient may be completely asymptomatic.