CHAPTER 30: Toxicology

DECONTAMINATION AND ENHANCED ELIMINATION

ACTIVATED CHARCOAL

• Decreases absorption of some drugs in the stomach, however not routinely recommended unless a potentially toxic amount of poison has been ingested

• Should be used soon after ingestion, ideally within the first hour

• Technique: Activated charcoal given orally or by nasogastric (NG) tube at dose of 1g/kg (maximum, 100g); repeat dose 0.5–1g/kg every 4–6 hours, if necessary (see multiple-dose activated charcoal subsequently)

  • ✓ Ideally should achieve ratio of at least 10 g charcoal per gram of drug ingested

• Does not bind metals (iron, lithium, lead) or common electrolytes, mineral acids/bases, alcohols, cyanide, solvents, and water-insoluble compounds such as hydrocarbon

• Poses aspiration risk, especially among who vomit or receive charcoal via NG tube

• Contraindicated in caustic or hydrocarbon ingestion and in patients without protected airway (altered mental status or unconscious)

GASTRIC LAVAGE/GASTRIC EMPTYING

• Gastric lavage still performed, but exceedingly difficult in young children due to size of tube required

• Efficacy not proven, but most effective if done within 1 hour of ingestion

• Technique: Place patient on left side with head lower than body. Use large bore orogastric tube

  • ✓ Aspirate gastric contents prior to lavage

  • ✓ Lavage with normal saline until return of fluid is clear. Fifty to 100cc per cycle should be used, and up to 200cc in adolescents

• May delay administration of charcoal

• Contraindicated in patients with altered mental status (inability to protect airway), hydrocarbon or caustic ingestion, cardiac arrhythmia, or possibility of foreign body ingestion

• Syrup of ipecac no longer recommended

EXTRACORPOREAL REMOVAL

Includes methods such as hemodialysis, plasmapheresis, and exchange transfusion

• Reserved for life-threatening poisonings or renal failure; consult pediatric nephrologist

• Hemodialysis is most commonly used. Blood is pumped through dialysis machine and toxins diffuse passively from blood into dialysate solution

• Unstable patients may undergo continuous renal replacement therapy (CRRT, such as continuous veno-venous hemofiltration or CVVH) but the efficacy for poisoning is much less

• Plasmapheresis and exchange transfusion are seldom necessary but may be useful in the neonates or infants

ENHANCED ELIMINATION

• Urinary alkalinization enhances clearance of certain agents such as salicylates, phenobarbital, chlorpropamide via “ion trapping”

  • ✓ Alkaline environment favors generation of ionized drug species which cannot readily cross the renal tubular membrane, thus preventing reabsorption

  • ✓ Performed with sodium bicarbonate at 1–2 mEq per kg over 1–2 hours with careful monitoring for electrolyte abnormalities

• Whole bowel irrigation (WBI):

  • ✓ Uses: Iron ingestions, massive ingestions, ingestion of sustained-release or enteric-coated preparations, ingestion of packets of illicit drugs, late presentations when gastric emptying and charcoal will be unlikely to be effective, and when charcoal cannot be used, such as in lithium ingestion

  • ✓ Technique: Give preparation via NG tube until stool is clear

  • ✓ Use polyethylene glycol solution, such as GoLYTELY at 500cc/h in children and 2L/h in adolescents

  • ✓ Contraindicated in patients with ileus ...