Toxicology Flashcards
<div><b>Indications For Dialysis in Lithium Poisoned Patients</b></div>
<div>Severely symptomatic patients </div>
<div>Unable to tolerate fluid hydration </div>
<div>Renal impairment </div>
<div>Acute toxicity: Levels above 4 mEq/L </div>
<div>Chronic toxicity: Levels above 2.5 mEq/L</div>
<div><b>List the ECG changes potentially seen in lithium toxicity</b></div>
<div><b>Think about it as looking at an ECG from P to T waves</b></div>
<div><br></br></div>
<div>Bradycardia </div>
<div>AV blockade </div>
<div>QT prolongation<br></br></div>
<div>ST changes </div>
<div>Ischemic changes<br></br></div>
<div>Flattened or inverted T-waves </div>
<div>+</div>
<div>Brugada pattern</div>
<div></div>
“<div><span>List risk factors for toxicity in the setting of chronic lithium use</span></div>”
<div><i>Renal causes:</i><br></br> Nephrogenic DI </div>
<div> Renal impairment </div>
<div><i>Hypo</i>:<br></br> volemia</div>
<div> Na</div>
<div><i>Acute illness </i></div>
<div><i>Drugs:</i><br></br> Diuretic<br></br> NSAIDS<br></br> ACE/ARB </div>
<div><i>Dementia /Increased age</i></div>
<div><b>List disease states caused by Lithium</b></div>
Nephrogenic DI<div>Hypothyroidism</div><div>Hyperthyroidism</div><div>SILENT</div>
What is SILENT
“<div><span>syndrome of irreversible lithium-effectuated neurotoxicity</span></div><div><div><span>Persistent cerebellar and brainstem dysfunction, dementia, and extrapyramidal signs even after lithium use has been discontinued for more than 2 months</span></div></div>”
List three deadly clinical manifestations of clonidine toxicity
<div>Apnea/hypoventilation</div>
<div>Hypotension</div>
<div>Bradycardia</div>
Substances Causing Wide Anion-Gap Acidoses
“<b>A CAT PILES MUD</b><br></br><b><br></br></b><div><b>A: A</b>lcoholic ketoacidosis<br></br><b>C: C</b>yanide,<b>c</b>arbon monoxide (CO),<b>c</b>olchicine<div><b>A: A</b>cetaminophen (large ingestions)<br></br><b>T: T</b>oluene<br></br><b>P: P</b>araldehyde,<b>P</b>henformin</div><div><b>I: I</b>soniazid,<b>i</b>ron,<b>i</b>buprofen</div><div><b>L: L</b>actic acidosis<br></br><b>E: E</b>thylene glycol<br></br><b>S: S</b>alicylates<br></br><b>M: M</b>ethanol,<b>m</b>etformin</div><div><b>U: U</b>remia<br></br><b>D: D</b>iabetic ketoacidosis</div></div>”
Potentially Lethal Toxins Where Early Activated <br></br>Charcoal Administration May Be Indicated
<b>THE KILLER CS</b><br></br>Cyanide<br></br>Colchicine<br></br>Calcium channel blockers<br></br>Cyclic antidepressants<br></br>Cardio glycosides<br></br>Cyclopeptide mushrooms <br></br>(Amanita phalloides)<br></br>Cocaine<br></br>Cicutoxin (water hemlock)<br></br>Salicylates
Substances That Do NotBind to Activated Charcoal
<b>SAPHIL</b><div><b>S</b>olvents</div><div><b>A</b>lcohols, Acids, Alkalis</div><div><b>P</b>esticides</div><div><b>H</b>ydrocarbons, Heavy metals</div><div><b>I</b>ron</div><div><b>L</b>ithium</div>
Dialyzable Toxins
<b>STUMBLED</b><br></br>Salicylates<br></br>Theophylline<br></br>Uremia<br></br>Metformin/methanol<br></br>Barbiturates<br></br>Lithium<br></br>Ethylene glycol<br></br>Depakote (valproic acid—in massive overdose)
Substances Amenable to Multiple-Dose <br></br>Activated Charcoal
ABCDQ<br></br>Aminophylline/theophylline<br></br>Barbiturates<br></br>Carbamazepine/concretion forming drugs (eg, salicylates)<br></br>Dapsone<br></br>Quinine
Nalaxone dose in Clonidine Toxicity
<div>Escalating doses of naloxone of 0.1 mg, 0.4 mg, 2 mg, and 10 mg</div>
What is indicated in refractory Bradycardia in Clonidine Toxicity
Atropine
Clonidine withdrawal S/S
Htn<div>Anxiety</div><div>Tachycardia</div><div>Sweating</div>
GCS
“<img></img>”
Usual Bedside Tests
Blood Sugar (Accucheck)<div>ECG</div><div>Urine Preg test</div>
””“<u>Must have lab tests</u>”” in acute toxicity”
<div>Venous gas</div>
<div>Electrolytes</div>
<div>Bun</div>
<div>Cr</div>
<div>Tylenol level</div>
<div>Salicylate level</div>
<div>ETOH</div>
Universal Antidote
“Glucose<div>Oxygen</div><div>Thiamine</div><div>Nalaxone</div><div>"”Flumazenil”” in certain conditions esp children</div>”
Goal of Nalaxone
“<span>Reversal of </span><u><span>respiratory</span></u><span> depression</span>”
Factors of persistent neurological sequelae after CO poisoning
<div>significant loss of consciousness or coma</div>
<div>persistent neurological dysfunction (e.g. confusion or seizures)</div>
<div>abnormal cerebellar examination</div>
<div>metabolic acidosis</div>
<div>myocardial ischaemia</div>
<div>age >55 years</div>
<div>pregnancy</div>
Antidotes
“<img></img>”
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TCA overdose<div>S in I</div><div>R in aVR</div>
ECG Findings in TCA overdose
S in lead I and aVL<div>R in aVR</div><div>Wide QRS</div><div>Rt axis deviation</div><div>Sinus tachycardia</div><div><br></br></div><div><br></br></div>
Mechanisms of TCA toxidromes
Na channels blockade (QRS prolongation)<div>K channels blockade (QT prolongation)</div><div>Antihistamine (hypotension, sedation)</div><div>Anticholinergic toxidrome</div><div>Serotonin syndrome</div><div>GABA blockade (seizure)</div><div>Alpha-1 blockade (hypotension)</div>
Whatis the leading cause of in-hospital death from TCA overdose
“Refractory Hypotension due to:<div>Profound alpha antagonism</div><div>Decrease myocardial contractility leading to decrease cardiac output</div>”
How do you ‘set up a sodium bicarb infusion
Add 2 amps to 1 L of D5W and infuse at ~150-250 cc/hr
Target Serum ph in alkalinization
Ph 7.45 - 7.55
Indications of Na bicarb in TCA overdose
QRS widening<div>Refractory hypotension</div><div>Ventricular Dysrrhthmia</div>
Antiarrhythmic medication of choice in TCA
Lidocaine
Hunter Criteria
“<img></img>”
Agents causing serotonin syndrome
“<img></img><div><span><br></br></span></div><div><span><b>S</b>aints <b>S</b>ell <b>D</b>rugs <b>T</b>hat <b>M</b>ake <b>M</b>e <b>T</b>rip <b>O</b>nthe<b>T</b>ram <b>L</b>ine</span><div><span>St. John’s Wart</span></div><div><span>SSRI/SNRI</span></div><div><span>Dextromethorphan</span></div><div><span>TCA</span></div><div><span>Meperidine</span></div><div>MAOI</div><div>Triptans</div><div>Ondensterone</div><div>Tramadol</div><div>Linzolid</div><div><span><br></br></span></div></div>”
Pathognominic dysrhythmia associated with digoxin toxicity
“<span><b>Paroxysmal Atrial tachycardia (PAT) with block</b></span><div><b><i>Bidirectional VT</i></b><br></br></div>”
ECG findings in Digoxin Toxicity
PAT with AV block (most common)<div>Frequent PVCs (Bigeminy & trigeminy)</div><div>Slow AF</div><div>Any type of AV Block</div><div>VTs including plymorphic and bidirectional VT</div>
<div>Indications of DigiFab in Acute digoxin overdose</div>
<ul> <li>Cardiac arrest</li> <li>life threatening cardia dysrhythmia</li> <li>ingested dose >10mg (adult) or >4mg (child)</li> <li>serum digoxin level >15 mmol/L at any time</li> <li>serum potassium >5.5 mmol/L</li></ul>
“<img></img>”
Paroxysmal atrial tachycardia with AV block<div>Digitoxicity</div>
Is it indicated to replace Ca in cases of Digitoxicity
“No, will result in ““stone heart”””
How much DigiBind to use
Acute: Start with 5-10 vials<div>Chronic: Start with 3-5 vials</div><div>Cardiac arrest: Start with 10 vials</div>
[K] in digitoxicity
Hyper K in acute<div>Hupo K in chronic</div>
<div>List three plants that have the potential to cause digitalis toxicity</div>
“<div>Common oleander </div> <div>yellow oleander </div> <div>Lily of the valley </div> <div>Red squill </div> <div>Foxglove </div> <div>dog’s bane </div> <div>Milkweed</div>”
What is the main route of Digoxin elimination
Kidneys
What is The definition of hepatotoxicity after paracetamol overdose
<div>serum AST concentration ≥1000 IU/L.</div>
Tylenol toxic doses
<div>In adults and adolescents, hepatic toxicity may occur following ingestion of >7.5.</div>
<div>In children the toxic dose is 140 mg/kg</div>
NAC should also be started immediately or empirically when
<div>Patients present 8 hours or more after ingestion</div>
<div>Serum Acetaminophen level is not available within an 8-hour time window</div>
<div>There is uncertainty as to the timing of the overdose</div>
<div>When do you start NAC in chronic ingestion?</div>
“<div><i>Chronic ingestion = any ingestion(intentional, unintentional supratherapeutic) > 8hr period </i></div> <div><br></br></div><div>Toxic level > 7.5 grams (adult) </div> <div>Symptomatic regardless of APAP level </div> <div>Elevated AST (> 2x upper limit normal or above 120 IU/L) </div> <div>Elevated APAP > 30 mcg / ml </div> <div>**Controversial: all high risk pts (etoh and liver dx) w/ elevated AST **</div>”
<div>What individuals are at increased risk for hepatocellular toxicity from chronic ingestion of APAP:</div>
<div>ETOH use </div>
<div>Isoniazid use </div>
<div>Malnutrition </div>
<div>Dehydration</div>
<div>List three differences between oral and IV NAC</div>
“oral:<div>more n/v,</div><div>takes longer,</div><div>less anaphylactoid rxns</div><div><br></br></div><div>OR</div><div><br></br></div><div>IV regimen is quicker than oral (20 hrs vs 72 hrs) <br></br>IV produces more anaphylactoid reactions compared to oral<br></br><br></br><span>Also acceptable:</span><br></br><span>(1) dosing errors are more likely with IV NAC</span><br></br><span>(2) possibly too much IV fluid for kids: potentially leading to hyponatremia and seizures</span><br></br><span>(2) The oral route frequently causes nausea and vomiting whereas the IV route does not</span><br></br></div>”
<div>Rumack-Matthew Nomogram is not useful in:</div>
<div>Chronic Overdose > 8 hrs</div>
<div>Delayed release tabs</div>
<div>Unknown time of ingestion<br></br></div>
<div>Co-ingestion (anticholinergics, ETOH)</div>
<div>glutathione deficiency<br></br></div>
<div>Chronic liver diseases</div>
<div>Malnutrition</div>
<div>HIV infection</div>
<div>Cystic fibrosis</div>
<div>When can you stop NAC?</div>
<ol> <li>INR <1.3</li> <li>AST or ALT WNL</li> <li>Non-Detectable acetaminophen level in the blood</li></ol>
<div>Describe criteria for transfer to a transplant centre</div>
<div>Kings College criteria, as per MDCalc, </div>
<ol> <li>Arterial pH < 7.30 </li> <li>INR > 6.5 (PT > 100 sec) </li> <li>Creatinine 300 µmol/L </li> <li>Grade III or IV hepatic encephalopathy</li></ol>
<div>Dosing of NAC:</div>
<div>Oral:</div>
<div>Loading dose: 140 mg/kg, then</div>
<div>70 mg/kg q4hrs for 17 additional doses.</div>
<div></div>
<div>IV:</div>
<div>Loading dose: 150 mg/kg iv, then</div>
<div>Continuous infusion og 50mg/kg over 4 hrs, then</div>
<div>Continuous infusion of 100 mg/kg over the next 16 hrs</div>
List 6 classes of medications that can cause an anticholinergic toxidrome
<div>Antihistamines, </div>
<div>Antiparkinson agents, </div>
<div>antipsychotics</div>
<div>Antidepressants</div>
<div>mydriatics</div>
<div>antispasmodics</div>
<div>muscle relaxants</div>
Causes of acidosis in toxic alcohols
Methanol: formic acid<div>Ethylene glycole: glycolic acid</div><div>Isopropanol: acetone (not an acid) result in ketonuria wout metabolic acidosis</div>
End-organ effect of txic etoh
” <div><span>Alcohol</span></div> <div><span>End Organ</span></div> <div>Methanol:</div> <div>Eyes: Blindness, GIT: Pancreatitis</div> <div>Ethylene glycol:</div> <div>Kidney: oxalic acid crystals: ARF</div> <div>Isopropanol:</div> <div>Hemorrhagic gastritis</div> “
Causes of Double Gap
<ol> <li>Ketoacidosis (diabetic, alcoholic).</li> <li>Alcohols (Ethylene glycol, methanol)</li> <li>Failures (renal, multiorgan)</li></ol>
<div>Which vitamins are important in the treatment of ethylene glycol poisoning?</div>
“<div>Pyridoxine 100 mg and thiamine 100 mg IV/IM drive the conversion of ethylene glycol to nontoxic metabolic’s.</div><div><br></br></div><div>Calcium replacement may also be necessary</div><div><br></br></div><div>For methanol, folate 50 mg IVq4h to drive conversion of formic acid to Co2 and H2O<br></br></div>”
<div>Ketosis is present in</div>
<ol> <li>diabetic ketoacidosis, </li> <li>alcoholic ketoacidosis, </li> <li>starvation ketosis, </li> <li>salicylism, and </li> <li>cyanide and acetone ingestion</li></ol>
<div>Advantages of Fomepizole over Ethanol:</div>
<div>More accurate dosing</div>
<div>Higher affinity to dehydrogenase</div>
<div><br></br></div>
<div>Less risk for:<br></br></div>
<div>Hypoglycemia</div>
<div>Electrolyte disturbances</div>
<div>CNS depression</div>
List 6 indications for hemodialysis in salicylate poisoning
<div>Clinical deterioration despite supportive care and urinary alkalinization</div>
<div>Salicylate level rising despite adequate therapy<br></br></div>
<div>Renal insufficiency or failure</div>
<div>Severe A/B disturbance</div>
<div>Altered mental status, or seizures</div>
<div>ARDS</div>
<div><br></br></div>
<div>How is ASA toxicity managed?</div>
<div>1. Start urinary alkalinization </div>
<div>2. Correct hypovolemia: Urine output 2-3 mL/kg/hr </div>
<div>3. Keep [K] >4.5, correct any hypomagnesemia </div>
<div>4. Give glucose for any CNS changes</div>
<div>What is the primary cause of mortality in ASA toxicity?</div>
“<div><span>cerebral toxicity and metabolic acidosis</span></div>”
<div>Which β blockers have intrinsic sympathomimetic activity?</div>
<div>Why is this important?</div>
“Pindolol<div>Acebutolol</div><div>Carteolol</div><div>Sotalol</div><div><br></br></div><div><div>can lead to some unusual manifestations such as v<span>entricular dysrhythmias and sinus tachycardia instead of bradycardia</span></div></div><div><br></br></div><div>Sotalol causes Torsades</div><div>Acebutolol causes prolonged QT and VT</div>”
<div>Why is propranolol the most lethal βB?</div>
“<div>Lipophilic nature which allows it to penetrate the CNS, causing <span>obtundation</span>, <span>respiratory depression</span>and <span>seizures</span>.</div>”
<div>HIET</div>
“<ul> <li><span>Insulin</span> and <span>glucose</span>.</li><li>Bolus 1 g/kg dextrose and run infusion at 0.5 g/kg/h.</li><li>Insulin starts at 1 U/kg and infuse at 0.5U/kg/h.</li><li>Increase in 1 hour if no hemodynamic response.</li></ul>”
<div>Which β blockers can be dialysed?</div>
“<div><span>SANTA</span> can’t pee….. </div> <ul> <li>Sotalol </li> <li>Atenolol</li> <li>Nadolol </li> <li>Timolol </li> <li>Acebutolol</li></ul>”
Indications of Deferoxamine
Fe level > 500 mcg/dL<div>Repeated vomiting, <br></br>toxic appearance, <br></br>lethargy, <br></br>hypotension, <br></br>shock</div><div>Metabolic acidosis</div><div>Hemochromatosis<br></br></div>
<div>What lab abnormalities are associated with HF burns?</div>
“HypoCa<div>HypoMg</div><div>HeperK</div><div>Metabolic acidosis</div><div><br></br></div><div><u>ECG findings:</u></div><div>prolonged QT</div><div>peaked T wave</div>”
Lab findings of NMS
Increased:<div>CK</div><div>WBC</div><div>BUN/Cr</div><div>LFT</div><div>Metabolic acidosis</div>
Toxins That Cause Hypoglycemia
“<img></img><div><br></br></div><div>Acetaminophen</div><div>ASA Alcohol</div><div>Sulfonylureas (Gliburide)</div><div>Insulin</div><div>BB</div>”
Medications causing NMS other than antipsychotics
Metoclopromide<div>Li</div><div>Antidepressants</div><div>Withdrawal of Antiparkinson medication</div>
<div>Common drugs causing nystagmus</div>
<div>Barbiturates</div>
<div>Carbamazepine,</div>
<div>PCP</div>
<div>Phenytoin</div>
<div>Lithium</div>