Poisonings and Environmental Exposures

1. Board Review 12/17/2012 Poisonings and Environmental Exposures

2. Test Question What topic should we do for January Board Review? • Adolescent • Disorders of the eye • Sports Medicine and Physical Fitness

3. Poisoning basics…

4. Poison Control Centers • Multiple VERY helpful resources • Data on signs and symptoms of toxicities • Can help identify unknown toxins • Management of ingestions • 1-800-222-1222 • Always have a high level of suspicion with an ingestion that there may be multiple agents involved • i.e. check an acetaminophen level when another ingestion is suspected • Very few initial signs/symptoms but high potential for poor outcome if missed

5. Basic Therapeutic Options for GI Decontamination • Emetics (ie syrup of ipecac) • Gastric Lavage • Activated Charcoal • Cathartics • Whole bowel irrigation

6. Question #1 A 4 year old is brought in by her parents because 20 minutes ago they found her playing with an empty bottle of grandmas atenolol which they knew previously had approximately 15 pills in it. You have a high suspicion that she ingested the medicine. She is anxious appearing but awake and alert with a heart rate of 70 and BP of 82/39. Which of the following would be the most appropriate action at this time? • Administer syrup of ipecac • Observation • Administer activated charcoal • Administer N-acetylcysteine • Draw an atenolol level

7. GI Decontamination • Emetics (ie syrup of ipecac) or gastric lavage • No longer recommended for use in the home or ER • Only possible use must meet these criteria: • Consultation with qualified medical personnel • Substantial risk or serious toxicity of the substance ingested • No access to any alternative therapy for at least 1 hour • Administration within 30-90 minutes of ingestion • Administration will not adversely affect later treatment (ie activated charcoal or N-acetylcysteine • Absolute contraindications: • Severe HTN or bradycardia • Risk of or current AMS • Ingestion of caustic, corrosive or hydrocarbon substance

8. GI Decontamination • Activated Charcoal • Organic product with numerous micropores that allow a large surface area of absorption • **ONLY method of GI decontamination supported by poison control centers** • Discussion about use in homes • Best if within 60 minutes of ingestion • Not for use when ingested substances are alcohols, corrosives, iron, or lithium; caution with hydrocarbons • Dosing:0.5-1g/kg (adult range 25-100g); 10:1 ratio of AC to ingested toxin • Can drink or give via OG/NG • Contraindicated in patients with unprotected airway

9. GI Decontamination • Cathartics (laxatives) • Limited use; ? Benefit • Sometimes given with dose of AC • Whole bowl irrigation • Enteral administration of osmotically balanced solution • Can be used after AC • Used for “body packers”

10. Question #2 A 3yo boy is brought to the ER at 7AM after his parents found him unresponsive in bed. The last time they saw him was at 2AM while they were cleaning up from a cocktail party. On exam he has diaphoresis and moans to painful stimuli. His vitals are T96.4, HR145, RR20, BP 83/34, Sp02 98%. His pupils are mid-sized and sluggish. Of the following, what is the MOST important test to obtain at this time? • Acetylcholinesterase determination • Bedside glucose • Blood alcohol level • Serum osmolality • Urine toxicity

11. Ethanol (ethyl alcohol) • Beverages, cough medications, mouthwashes, aftershaves • Multiple over-the-counter preparations • Clinical features • Dose-related CNS depressant • Ingestion of 0.5g/kg (1.5ml/kg body weight) can produce intoxication in a young child • Induces hypoglycemia (especially in children)** • Metabolism of ethanol creates a relative lack of pyruvateblocks gluconeogenesis  hypoglycemia • Hypothermia, inebriation, vomiting, ataxia, respiratory depression, coma, hypotension, death

12. Ethanol (ethyl alcohol) • May mask toxicities from other ingestion drugs** • Effects of stimulants are blunted • Effects of other depressants may be potentiated • Lab workup • Ethanol level, serum electrolytes, glucose • Watch for hypokalemia • Screen for other ingestions • Management • Supportive, IVFs • Correct electrolytes/glucose • No antidote; good prognosis

13. Question #3 Your 3yo child loves blueberry soda. You found him in the garage with an empty bottle of Windex. Upon arrival to the ER the child is lethargic and minimally responsive to painful stimuli. An ABG shows 7.11/30/60/12. All of the following are possible treatment modalities for this child, EXCEPT: • Ethylene glycol • Sodium bicarbonate • Leucovorin • Folate • Hemodialysis

14. Methanol • Windshield wiper fluid, cooking fuel, perfumes • Methanol itself causes n/v, inebriation • Metabolites (formaldehyde and formic acid) are more toxic • CNS depression, anion gap acidosis (can cause multiorgan dysfunction), optic changes • Testing: methanol level, ABGs • Treatment: • Sodium bicarb for acidosis • Folate or leucovorin (can help eliminate formic acid) • Ethanol: can help decrease formation of metabolites • Hemodialysis for severe cases

15. Ethylene glycol • Most commonly: Antifreeze • Causes severe metabolic acidosis and formation of calcium oxalate crystals in vital organs • Hypocalcemia • Nephrotoxicity • Treatment • Gastric emptying (if within 1hr) • Correction of acidosis and hypocalcemia • Thiamine and pyridoxine • Cofactors in the non-toxic pathway of ethylene glycol metabolism • Hemodialysis

16. Hydrocarbons • Gasoline is most common exposure • Irritating to GI and respiratory tract • Primary concern: chemical pneumonitis • Aspirated low-viscosity hydrocarbons spread to large areas of lung; destroy surfactant; alveolar collapse; VQ mismatch; hypoxemia • Direct capillary damage also leads to pneumonitis

17. Question #4 A2yo boy is brought to the emergency department by his father after they had spent several hours in the garage while the father worked on the car. The father reports that approximately 30 minutes ago he heard the child coughing and found him with an open bottle of lighter fluid in his hands. On exam, the child is awake and alert; temperature is 37.0°C, HR is 120 beats/min, RR is 24 breaths/min, BP is 90/60 mm Hg, and 02 sat 98%. Of the following, the MOST appropriate next step is to: • Obtain urine tox screen • Perform gastric lavage • Reassure the father and discharge the patient home • Obtain a STAT chest CT • Place the child under observation

18. Hydrocarbons • Clinical manifestations • Initial: oropharyngeal and gastric irritation • Coughing and choking: could indicate inhalation of fumes; does not necessarily imply aspiration • Vomiting from gastric irritation • Aspiration: significant coughing and respiratory distress • “petroleum” smell on breath, tachypnea, retractions, bronchospasm, wheezing, rales, • Fulminant chemical pneumonitis: marked SOB and hypoxemia • Fever within 6 hrs indicates tissue damage (not infection) • Pulmonary damage reaches peak at 3 days after aspiration

19. Hydrocarbons • Diagnosis • Based on history, signs/symptoms of respiratory involvement • If symptomatic: ABG, CXR • CXR findings can lag 4-6hrs after aspiration • Management • Asymptomatic patients: observe for 4-6 hrs • If abnormal CXR: consider admitting • Symptomatic: admit • Supportive care; no use for abx or steroids • Prognosis: good • Chemical pneumonitis often resolves completely • Rarely will have long term problems (pneumatoceles)

20. Tricyclic antidepressants(TCA) • Amitriptyline, clomipramine, desipramine, etc • Used in children to treat enuresis • Block acetylcholine, prevent reuptake of norepinephrine, and block sodium channels in the myocardium • Clinical toxicity begins with 6-8hrs of ingestion and peaks within 24hrs** • Clinical effects: • Anticholinergic! • Dry mouth, ileus, dilated pupils, urinary retention, tachycardia, HTN, flushed • CNS: delirium, agitation, restlessness, hallucinations, convulsions • Life threatening toxicity due to cardiac dysrhythmias

21. Question #5 You are called by the mother of a 3-year-old girl because the child appears confused and is pale and sweating. The mother thinks the child may have taken some of her grandmothers imipramine. You advise her to call 911 to have her taken to the ER. Of the following, what is the most appropriate action to take in the ER? • CXR to evaluate for pulmonary edema • EKG to monitor for dysrhythmia • ECHO to assess cardiac function • EEG to identify a seizure focus • Serum measurement of imipramine

22. TCAs • Work-up • Can check serum levels, but results do not contribute to treatment decisions • EKG** • Can help identify significant conduction defects • Prolonged PR • Widened QRS • Single most useful prognostic indicator for convulsions or dysrhythmias • OTc prolongation • Rightward shift of axis • AV block • Ventricular dysrhythmias

23. TCAs • Management • Activated charcoal for GI decontamination • CNS toxicity (convulsions) respond to benzos • Serial EKGs/monitor for the first 6 hrs after ingestion • For cardiac dysrhythmias: • Cardiac monitoring • Continued until all toxic effects have resolved for 24hrs • Sodium bicarb (1-2Meq/kg) • Prognosis is good • Resolution of toxicity generally in 24-48hrs • Can have late (2-5days after overdose) fatal dysrhythmia but this is found in seriously ill patients

24. Question #6 A 16yo girl is brought to the ER by her parents after she admitted to taking two handfulls of acetaminophen (500mg) because her boyfriend broke up with her. Which of the following is the MOST important piece of information you must obtain in order to determine your next course of action? • The name and address of the boyfriend • History of previous suicide attempts • How long ago the ingestion took place • A blood gas measurement • Glucose measurement

25. Acetaminophen • One of most common medications used to treat fever and pain in children • Most common analgesic overdose in children less than 6yo • Toxicity arises from metabolism of the drug • During hepatic metabolism of large doses, a toxic metabolite accumulates in the hepatocyte and causes damage to liver cells • Minimum toxic dose: 140mg/kg • Severe toxicity for ingestions >250mg/kg

26. Acetaminophen • Initial signs/symptoms: nonspecific; nausea/vomiting • Within 18-24hrs hepatic damage may become evident with increased LFTs • If not treated, hepatic damage may worsen • Either gradually resolves OR if severe, will progress to severe hepatic damage  hepatic failure • Hepatic failure: • Coagulation abnormalities • Encephalopathy • In young children: altered ‘sleep/wake’ cycles, irritability

27. Acetaminophen • Only accurate predictor of hepatic toxicity from acetaminophen is measurement of a level 4-10hrs after overdose • Levels that fall above nomogram line  may be associated with hepatic damage • Treatment • N-acetylcysteine • Should be started within 10 hours of ingestion

28. Question #7 A 7 yo boy is brought to the ER due to altered mental status. He was well when he came home from school, but when he came inside for dinner after playing outside with friends he complained of abdominal pain and had an episode of NBNB emesis. Over the next 30 min he became increasingly lethargic. In the ER, he is unresponsive and drooling. Temp is 98.8, HR is 50, RR is 36, BP is 100/60. Sp02 is 82% on room air. Pupils are small and sluggish. Breath sounds are coarse bilaterally with increased WOB. You suspect a toxin exposure. What is the most appropriate treatment? • Atropine • N-actylcysteine • Naloxone • Physostigmine • Ethanol

29. Organophosphates • Found in a wide array of products • Herbicides, pesticides, lawn care • 70% of exposures occur due to ingestion of improperly stored products • Mechanism of action: (Cholinergic poisoning) • Irreversibly inhibits acetylcholinesterase leads to accumulation of acetylcholine  excess acetylcholine overstimulatesmuscarinic, nicotinic, central receptors • Muscarinic: “SLUDGE” (salivation, lacrimation, urination, diarrhea, gastric emesis), miosis,bronchorrhea/resp distress, sweating, bradycardia, hypotension • Nicotinic: muscle twitching, weakness, paralysis • Central: confusion/AMS, HA, tremor, seizure, coma

30. Organophosphates • Treatment • Decontamination • Skin washing, activated charcoal • Blocking effects of excess acetylcholine • Atropine: give every 10-30min until muscarinic effects gone • Reactivating acetylcholinesterase • Pralidoxime: best if given within 24-48hrs • Supportive measures • Ventilation, IVFs, vasopressors

31. Question #8 A 2-year-old boy is brought to the emergency department after his father found him with the leaf from a foxglove plant in his mouth. He has had one episode of emesis and is complaining of abdominal pain. On physical examination, his heart rate is 140 beats/min, respiratory rate is 24 breaths/min, blood pressure is 100/60 mm Hg, and oxygen saturation is 100%. His pupils are 4 mm and briskly reactive to 2 mm. The remainder of his examination findings are normal. After administering activated charcoal, what is the most appropriate next step? • Abdominal xray • EKG • Serum creatinephosphokinase • Serum sodium • Head CT

32. Toxic Plants • Ingestions most common in children < 6yo • Fewer than 10% result in need for medical treatment • Most ingestions are small in quantity and symptoms are generally short-lived • GI effects are most common • Treatment based on suspected ingestion/symptoms • ABCs • Decontamination: activated charcoal • Reversal: • Physostigmine for anticholinergic ingestion • Cardiac monitoring for cardiac glycoside ingestion • Call poison control for ANY question** • They can help identify unknown plant

34. Question #9 A 2 year old boy is brought to the ER because he has been difficult to arouse for an hour. The child is somnolent and responsive only to pain. His temperature is 101.5, HR 130, RR 56, and BP 90/60. ABG reveals pH 7.28/CO2 20/HCO3 15. The patient and his mom have been staying with grandma for the holidays. Mom is healthy, but the grandma takes a few different medications. The most likely explanation for this child’s findings is • Intracranial hemorrhage • Acetaminophen ingestion • Metoprolol ingestion • Sepsis • Aspirin ingestion

35. Salicylates

36. Aspirin Toxicity • Remains one of the most serious ingestions in the pediatric population • Toxic dose for a child = >150mg/kg • Salicylates are found in various household products (not just in Aspirin tablets) • Mouthwash • Face cleanser • Powders • Bismuth compounds • ETC…

37. Clinical Manifestations • Symptoms • Nausea and vomiting from DIRECT gastric irritation. • Altered hearing…usually tinnitus • Fever • Altered mental status • Agitation • Seizures • Stupor and coma • Signs • Tachypnea • Tachycardia • Non-cardiac pulmonary edema (due to increased vascular permeability)

38. Laboratory Findings • Anion gap metabolic acidosis!! • Methanol toxicity • Uremia • Diabetic Ketoacidosis • Paraldehyde ingestion • Iron/INH toxicity • Lactic acidosis • Ethylene glycol ingestion • SALICYLATES • So be sure to rule these things out! • Respiratory alkalosis • **in young children the metabolic acidosis tends to predominate

39. Laboratory Findings • Global hypokalemiadue to K+ excretion in the urine • Initial alkaline urine • HCO3 excreted in response to the respiratory alkalosis • Later…acidic urine as the kidney tries to preserve K+ in exchange for H+ (which is excreted) • Paradoxicaciduria in the face of respiratory alkalosis is a hallmark of aspirin toxicity • Salicylate levels • Peak 4-6 hours after ingestion • Correlate poorly with clinical symptoms • Should be followed q2-4 hours until decreasing or <30mg/dL

40. Question #10 You are admitting a patient to the PICU with findings suspicious for Aspirin toxicity. The patient was initially awake upon presentation and was already given activated charcoal. The initial salicylate level was 80mg/dL. You know that aside from supportive care, the next BEST step to enhance salicylate elimination is… • Gastric lavage • Alkalinization of the urine • N-acetylcysteine • 100% Oxygen • Acidification of the urine

41. Treatment • Upon presentation • Activated charcoal if the patient is alert • Gastric lavage is NOT usually recommended UNLESS • Ingestion was a large, life-threatening dose • Brought to medical attention within 1 hour • Correction of metabolic derangements and dehydration • Fluid boluses • Alkalinization to enhance salicylate elimination • Goal serum pH 7.5 , goal urine pH >7.5 • Rec: 1-2 mEq/kg bolus of NaHCO3 followed by a NaHCO3 drip • **Add K+ to fluids of patients without renal failure • Dialysis if level >100mg/dL or other worrisome signs • Intubation can suppress hyperventilation and may be dangerous!

42. Carbon Monoxide

43. Carbon Monoxide • Has no color, odor, or taste • Has come to be known as the “silent killer” • Accounts for most of the poisoning deaths in the US • 300-500 people die annually from unintentional poisoning • We, as pediatricians, need to be able to recognize the signs and symptoms

44. Pathophysiology • CO is inhaled and absorbed into the bloodstream • Forms carboxyhemoglobin by binding to hemoglobin with an affinity 250x that of oxygen • Unable to transport oxygen • Reduces oxygen delivery to the tissues by interfering with the dissociation of oxygen from the remaining oxyhemoglobin molecules • People (and organs) with higher metabolic rates are affected most • Infants and children are at a greater risk • Neurologic, cardiac, and pulmonary manifestations are seen more often

45. Clinical Manifestations • People living in the same home present with similar, nonspecific symptoms • Fatigue • Dizziness • Headache • Nausea • Irregular breathing or dyspnea on exertion • Palpitations • Irritability/confusion/irrational behavior • Patients may appear pale or cyanotic • Symptoms can progress to LOC and death • Symptoms may improve when patient leaves the place of exposure

46. Question #11 A 5 year old boy is brought to the ED for 2 days of HA, nausea, and vomiting. He is afebrile and does not have diarrhea. Everyone at home, including the dog, has the same symptoms. On PE, he is mildly irritable but alert and oriented, and his mucous membranes appear bright red. His lung exam is clear, but he does have some mild increased WOB. Sats are 100% on RA. What is the MOST appropriate next step? • Admit the patient for continuous pulse ox monitoring • Place the patient on 2L of O2 at 40% FiO2 • Obtain a carboxyhemoglobin measurement • Administer IV Methylene Blue • Arrange for emergent hyperbaric oxygen therapy

47. Diagnosis • Measurement of carboxyhemoglobin levels can confirm exposure. • Extent of exposure and/or measure CO-Hb levels may not correspond to severity • O2 saturations obtained by routine pulse ox is falsely normal because O2-Hb and CO-Hb cannot be differentiated on standard pulse ox techniques • ABG: metabolic acidosis with a normal PaO2

48. Management • Separate patient from the source of CO exposure • Decrease oxygen consumption by maintaining bedrest and diminishing anxiety • Oxygen • Should be provided until symptoms resolve and CO-Hb levels decrease to 5% or less • 100% O2 via non-rebreather mask • Decreases elimination half-life of CO to 1 hour • Ventilatory support if needed • Hyperbaric oxygen • Indications for use are debatable • EKG monitoring for cardiac dysrhythmia

49. Prevention • Counsel parents on important sources of exposure for children • Traveling in vehicles • Living in homes with poorly ventilated gas cooking and heating appliances • Vehicles idling in attached garages • Carbon monoxide detectors • Show promise • Effect on saving lives has not been demonstrated

50. Corrosives