Poisoning and environmental exposure to hazardous substances


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Poisoning and environmental exposure to hazardous substances

  1. 1. Poisoning and Environmental Exposure to hazardous Substances ♦General o Prevention and Risks o Poison Control Centers, online resources  Recognize the indications and contraindications of various emetics • Emetics= ipecac • In 2003 AAP said that ipecac should no longer be used in the home and that home supplies should be disposed of safely • There are times when it might be utilized, but only after consultation with qualified medical personnel: ∗ Substantial risk of serious toxicity from the ingestion ∗ No access to emergency dept or alternative tx for at least one hour ∗ Administration within 30 to 90 mins of the ingestion ∗ Knowledge that administration would not adversely affect later tx (of note, AC is no longer contraindicated regarding N-acetylcysteine usage) • Contraindications: medical conditions that may be exacerbated by vomiting (bradycardia, sever hypertension); risk or or an acutely altered mental status; ingestion of a caustic or corrosive substance; ingestion of a hydrocarbon o Therapeutic options for poisoning  Know the appropriate use of cathartics in poisoning • Cathartics = laxatives • Generally have no role in the tx of the poisoned patient • Despite lack of evidence a single dose is often given with AC  Know the indications for gastric lavage • “stomach pumping”; giving and then aspirating warm saline via large bore OG • generally not recommended due to possible risks (perforation, electrolyte imbalances) • can be reserved for use in life threatening ingestions that have occurred recently • same contraindications as for ipecac  Understand the management of childhood poisonings o Recognition of ingestion of unknown substances  Understand the management of poisonings by an unknown agent or multiple agents • Initial assessment is to stabilize the vital functions, treat the patient’s symptoms and identify agents that are potentially fatal, have delayed clinical toxicity, or have indicated antidotal therapies • Do a screening hx to identify circumstances surrounding the event, potential agents/exposures, available meds or toxins, prior med or psych hx • PE should focus on vitals, papillary size and reactivity, skin findings and mental status • Lab should focus on acid-base status, oxygenation and ventilation, glucose concentration, anion gap, always measure salicylate and acetaminophen levels in pt’s with an unknown/mixed ingestion ♦Specific acute poisonings, ingestions and exposures o Nonsteroidal analgesics
  2. 2.  Recognize the signs and sx of apap toxicity • Early signs (first few hours) are anorexia, nausea, vomiting, resolve by about 12-24 hours • Latent toxicity (1-4 days post-ingestion) has the increased liver enzymes; when toxicity is severe the jaundice and liver toxicity develop during the end of the latent phase  Understand the management of a suspected or confirmed apap overdose • N-acetylcysteine is highly effective antidote, but has to be given within the first 10 hours • If the timing of the ingestion is known you probably have time to wait for a serum apap level and see where it falls on the chart to decide if it is indicated • If the amount of ingestion is known (minimal toxic dose is 140mg/kg) then can go ahead and give it, especially is it will take awhile to get the level back  Plan the management of a patient with toxic ingestion of ibuprofen • Always check for co-ingestion, i.e. serum testing for apap and salicylate • Death by ibup ingestion is rare, but complications have included duodenal perf, renal toxicity, metabolic acidosis, somnolence and coma o Opiates  Recognize the signs and sx of an opiate overdose • Miosis, respiratory depression, CNS depression; other manifestations can include bronchospasm, noncardiogenic pulmonary edema, peripheral vasodilation, orthostatic hypotension, dysrhythmias, dysphoria, mydriasis, szs, nausea, vomiting, constipation, flushing and pruritus  Understand the management of an opiate overdose • Priority is establishment of effective ventilation and oxygenation, followed by hemodynamic support and administration of an opioid antagonist (naloxone) • Naloxone given as 0.1 mg/kg with max dose of 2mg; may need to be repeated several times, even continuously • Observation or admission indicated for those with recurrence of respiratory depression or pulmonary edema or who have ingested long-acting or delayed absorption opioids o Anticholinergic substances  Recognize the signs and symptoms of anticholinergic drug use • “hot as a hare, dry as a bone, blind as a bat, red as a beet, mad as a hatter” • also with tachycardia and hypertension commonly • treatment is primarily supportive, followed by appropriate decontamination o Salicylates  Recognize the signs and sx of salicylate toxicity • Emesis and nausea, altered hearing (usually tinnitus), fever and altered mental status • Rapid breathing and respiratory distress • Initial derangement = respiratory alkalosis via direct stimulation in the CNS causing hyperpnea; then get metabolic acidosis related to decoupling of oxidative phosphorylation causing anaerobic metabolism  Understand the management of salicylate toxicity • If alert, give activated charcoal
  3. 3. • Fluid boluses to tx the severe dehydration but cautiously as may have pulm edema • Alkalinization is key; and goal for serum pH is 7.5 and urinary pH >7.5; achieved with sodium bicarb drip • Give K+ as likely to have hypoK • If level is >100mg/dL will need dialysis • Intubation can be considered, but it might override the body’s own compensatory mechanism of the hyperventilation and they could get a worsening acidosis o Antihypertensives  Recognize the signs and sx of ingestion of medications that produce hypotension • Beta blockers: decreased HR and BP, depressed sensorium • ACEi, hydralazine: tachycardia, hypotension o TCAs  Understand the danger of TCA treatment is an accidental ingestion by siblings  Understand the cardiac dysrhythmias that may occur late after ingestion of TCAs • Need to measure voltage intervals, both the QRS and the QT • Prolonged QT can lead to the ventricular dysrhythmias  Know that an overdose of some antidepressants can cause dysrhythmias  Recognize the signs and sx of TCA toxicity • Primarily affect the CNS, autonomic NS and CV • CNS si/sx include irritability, euphoria, seizures, unresponsiveness • ANS (anticholinergic) si/sx include mydriasis, dry skin, dry mouth, urinary retention, tachycardia, hyperthermia • CV sx can be prolonged conduction, depression of myocardial contractile function, prolongation of the QT and QRS ∗ The QRS gets longer due to the direct TCA effects leading to blockade of the fast sodium channels  Plan the initial management of TCA toxicity • Initial management needs to include airway protection, restoring adequate ventilation, perfusion, oxygenation; may need intubation, mechanical ventilation, fluid rescues, pressors (norepi) • Seizures to be txed with benzos • For QRS prolongation, give sodium bicarb until it is <100 milliseconds o Ethanol  Know that ethanol may cause hypoglycemia  Know that ethanol toxicity may mask toxicities from other drugs  Be aware of potentially harmful additives in OTC medications (e.g. ethanol in mouthwash, salicylate in anti-diarrheal products) • Ethanol is in mouthwash, cough and cold preparations, elixirs and perfumes  Recognize the signs and sx of methanol ingestion • Methanol toxicity comes from the metabolic products: formic acid and formeldahyde • Causes CNS depression, acidosis with anion gap, optic changes (reversible or irreversible)
  4. 4. • The acidosis may result in multiorgan dysfunction • Treatment is correction of acidosis with Na bicarbonate, giving folate to prevent the formation of formic acid and also giving alcohol dehydrogenase antagonists (ethanol and 4-MP, but 4-MP isn’t available in the US) o Hydrocarbons  Know how to manage a child who has ingested a substance containing a hydrocarbon • If asymptomatic they might only need to be observed for 4-6 hours • If symptomatic then the resp distress should be managed with oxygen, a trial of bronchodilators, supportive care • The si/sx of ingestion of a hydrocarbon may reveal the smell of it on the kid’s breath, wheezing, laryngospasm, other signs of resp distress. Ingestion may cause coughing or vomiting o Organophosphates  Recognize the signs and sx of organophosphate poisoning • SLUD syndrome is what is classic but it may not be that apparent in kids (salivation, lacrimation, urination and defectation) • Kids usually present with CNS symptoms (AMS, lethargy, seizures), respiratory distress, muscle weakness, GI complaints, miosis and excessive salivation • Dx made by having low serum concentration of pseudocholinsterase or erythrocyte acetylcholinesterase  Understand the management of organophosphate poisoning • Treatment is directed toward decontamination and includes skin washing, hair washing, gastric lavage, AC and laxatives • Atropine is used to block the effects of acetylcholine excess (counteracts the muscarinic effects) ∗ Needs to be given every 10-30 mins as needed to counteract the muscarinic effects ∗ Given before the pralidoxime • Pralidoxime is used to reactivate the irreversibly inhibited acetylcholinesterase ∗ Ideally given with 24 hours after the exposure, otherwise the acetylcholinsterase/organophosphate complex has “aged” and the inhibition can’t be reversed • Organophosphates are in herbicides and pesticides o Carbon monoxide  Recognize the signs and symptoms of carbon monoxide poisoning, and manage appropriately • CO binds to Hbg with 200x affinity of O2 and causes the O2 dissociation curve to shift to the left, leading to decreased tissue O2 delivery and tissue hypoxia • Common sx = headache, dizziness, weakness, nausea, confusion, SOB, vision changes • Severe poisoning = dysrhythmias, hypotension, rhabdo, myocardial ischemia, cardiac or respiratory arrest, noncardiogenic pulmonary edema, seizures and coma • Chronic exposure = HA, nausea, cerebellar dysfxn, mood disorders, low birthweight, reduced exercise tolerance, polycythemia, cardiomegaly  Know how to manage a child with carbon monoxide poisoning
  5. 5. • Acute poisonings = oxygen administration, possibly hyperbaric oxygen • Also need to give support to airway, breathing and circulation o Acids, alkali and alkaloids  Know the common household sources of acids and alkali  Plan the appropriate management of a child who has ingested dishwasher detergent • Is a caustic alakali and can cause deep liquefactive necrosis of affected tissues, ulceration and perforation • Often have drooling, dysphagia, emesis • Initial eval after ingestion of anything caustic includes stabilizing vitals, pain control, other supportive measures • In the symptomatic patient, endoscopy should be undertaken in 6-24h of ingestion to determine the severity / presence of esophageal burns • If asymptomatic, endoscopy is recommended if there are clear cases of ingestion ; if ingestion questionable than may be able to just observe for several hours for any signs of symptoms  Recognize that gastric lavage is contraindicated in a caustic ingestion  Recognize that corrosive material such as hydrochloric and sulfuric acids can be transported to the stomach with few or no esophageal burns, causing severe gastritis, perforation, or late stricture formation  Recognize the role of endoscopy after a corrosive ingestion • See above  Recognize the signs and symptoms following alkaloid (e.g. gun bluing) ingestion • See injury to the mucosal surfaces (white eschars), drooling, dysphagia, odynophagia, intraoral burns, vomiting (maybe hematemesis), resp distress with stridor or wheezing, burns on the face/hands/chest • RARE systemic sx, CNS usually NL o Button batteries  Know how to manage a child who has ingested a button battery • Have to try and get it out of the esophagus o Coins  Know how to manage a child who has ingested a coin o Iron  Understand how to manage a child with iron ingestion • If symptomatic within 6 hours after ingestion, regardless of how much they took, they need immediate eval • If asymptomatic, know that ingestions of <40mg/kg of elemental iron are not significant and can be observed at home; if remain asx for more than 6 hours then likely to be okay, if develop sx then need to be seen • In cases of significant ingestion they need to have Fe levels checked within 4 hours of ingestion, also other lab work • Get radiography to see if any still in GI tract and then do decontamination; • If severe sx serum Fe >500, or lots of pills on imaging then need to give deferoxamine; activated charcoal won’t do anything • o Ethylene glycol  Recognize the signs and sx of ethylene glycol ingestion
  6. 6. • Severe metabolic acidosis and formation of calcium oxalate crystals in vital organs, resulting in hypocalcemia and nephrotoxicity • Therapy = gastric emptying (if within one hour of the ingestion), correcting acidosis and hypocalcemia, and giving thiamine and pyridoxine (are cofactors on the nontoxic metabolic pathway of ethylene glycol) ♦Exposure to toxic substances in the environment o Age related risk and impact of exposure  Understand why infants are at greater risk than adults to toxic substances in the environment • They have a high degree of hand to mouth activity that increases their chances of ingesting contaminated stuff (paint chips, house dust, soil) • They may absorb it more efficiently than adult • They ingest more food and water than adults (adjusted for body weight) • Since they have a longer lifespan ahead of them they are more likely to acquire dzs that have a long latency period o Obtaining an exposure hx  Know how to obtain hx of exposure to toxic substances in the environment o Contaminants in drinking water  Know the contaminants potentially found in drinking water (e.g. e. coli, cryptosporidium, trichloroethylene, perchlorethylene) o Contaminants in food  Know the toxic substances that may contaminate food sources (e.g. mercury, e. coli) o Chemical hazards in the community  Recognize the toxic substances that may contaminate the environment and affect the health of children (e.g. pesticides, industrial waste) o Chemical exposures in the home  Know the potential occupational exposures that directly or indirectly affect the health of children  Recognize the common exposures and health problems that are associated with renovation and repair o Exposures from terrorism (e.g. anthrax, smallpox)  Recognize the characteristic skin lesions of anthrax  Differentiate the skin lesions of varicella from those of smallpox