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Critical Care & Toxicology > Toxicology > Flashcards

Toxicology Flashcards

1
Q

How is the anion gap calculated?

A

AG = Na - Cl - Bicarb

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2
Q

How is the osmolar gap calculated?

A

Osmolar Gap = Serum (Osm) - Calc (Osm)

Calculated Osm = 2xNa + Glucose + BUN + 1.25xEtOH

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3
Q

What is the different between a sympathetic and anti-cholinergic toxodrome?

A

Sympathetic - Sweat

Anti-Cholingeric - Dry

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4
Q

What is a classic cause of cholinergic crisis/toxicity?

A

Organophosphates

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5
Q

What are the classic features of anticholinergic toxicity (6)?

A

(1) Red as a beet - flushed
(2) Dry as a bone - urinary retention, ileus.
(3) Mad as a hatter - sedation, confusion, delirium, confusion.
(4) Blind as a bat - mydriasis, dilated pupils that don’t respond to light.
(5) Hot as a hare - hyperthermia

  • Also seizures
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6
Q

What are two common causes of anti-cholinergic toxicity/overdose?

A

Gravol

Tricyclic Anti-Depressants

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7
Q

What are the cardiac concerns for anti-cholinergic (ie. TCA) overdose?

A

Arrhythmia - VF/VT as QRS widens.

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8
Q

What acid base disorder would you expect to see in anti-cholinergic toxicity?

A

Respiratory acidosis due to decreased level of consciousness.

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9
Q

What are the ECG features of TCA overdose (4)?

A

(1) Prolonged QRS
(2) Tall R in AVR (R/S ratio > 0.7)
(3) Deep slurred S in I & AVL
(4) Type I Brugada (RBBB, downslope ST depression in V1-V3)

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10
Q

How do you treat TCA overdose?

A

(1) Activated charcoal (can give > 2 hrs because anti-cholinergics slow gastric emptying) if normal LOC.
(2) Manage seizures with benzodiazepines, midazolam infusion if refractory, followed by propofol and barbiturates. DO NOT use phenytoin.
(3) Sodium bicarbonate for wide complex tachycardia, ventricular arrhythmia, hypotension, or QRS > 100. Target pH between 7.50-7.55. Can bolus 1-2 amps and then run an infusion (3 amps in D5W at 250 cc/hr).
(4) If all else fails -> intralipid and VA ECMO can be considered.

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11
Q

What is the complication of methanol that you are trying to avoid in toxicity?

A

Retinal injury leading to blindness.

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12
Q

What might you see on exam that can help differentiate ethylene glycol toxicity from methanol?

A

Ethylene Glycol - CN Palsies

Methanol - Eye findings - RAPD, mydriasis, retinal sheen, hyperaemia of optic disc.

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13
Q

What laboratory abnormality do you need to watch for in ethylene glycol toxicity?

A

Hypocalcemia - can get prolonged QT if significant.

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14
Q

What can cause a high anion gap, high osmolar gap acidosis (5)?

A

(1) Ethylene Glycol
(2) Methanol
(3) Ketoacidosis (Ethanol or Diabetic)
(4) Propylene Glycol
(5) ESRD with no IHD

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15
Q

What is the role of decontamination in toxic alcohol ingestion?

A

No role, unless they present within 60 minutes, in which case you can try NG aspiration.

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16
Q

What is the role for enhanced elimination in toxic alcohol ingestion?

A

Acidemia allows toxic metabolites to penetrate end-organ tissues - give bicarb infusion at 150-250 cc per hour to target a goal pH of 7.35.

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17
Q

What are the indications for fomepizole or ethanol in toxic alcohol ingestion?

A

(1) Serum methanol > 6.2 mmol/L or ethylene glycol > 3.2 OR
(2) Document hx of ingestion of toxic amounts and an osmolar gap > 10 OR
(3) Suspicion for ingestion and at least 2 of the following:
(A) pH < 7.3; (B) Bicarb < 20; (C) OG > 10; OR (D) Urine oxalate crytals.

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18
Q

What are the indications for hemodialysis in the treatment of toxic alcohol ingestion?

A

High AG metabolic acidosis and evidence of end-organ damage.

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19
Q

What are the early findings (first 1-2 hrs) of ASA overdose (4)?

A

(1) Tinnitus
(2) Nausea/vomiting
(3) Hyperventilation
(4) Fever

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20
Q

What are the late findings of ASA overdose (5)?

A

(1) Coma/seizures
(2) Non-cardiogenic pulmonary edema
(3) Arrhythmia
(4) Thrombocytopnea
(5) AKI

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21
Q

How often should you monitor salicylate levels in ASA overdose?

A

Every 2-4 hours until improving

22
Q

What is a toxic level of serum salicylate?

A

Toxicity Serum > 2.9-3.6

23
Q

What is the role of decontamination in ASA overdose?

A

Can use activated charcoal if the patient presents within 2 hours (or longer if enteric coated or bezoar formation) of ingestion.

Also consider whole bowel irrigation.

24
Q

What is the role of enhanced elimination in ASA overdose?

A

You do want to alkalinize the urine and blood in ASA overdose to enhance elimination.

Target blood ph 7.4-7.5 and a urine pH of 7.5-8 using bicarbonate infusion at 250 cc/hr.

  • Need to correct hypokalemia first.
25
Q

What are the indications for dialysis in ASA overdose?

A

(1) Salicylate Level > 7.2 mmol/L
(2) Hypoxemia requiring supplemental O2
(3) Altered mental status
(4) Renal failure and level > 6.5
(5) Progressive vital sign deterioration
(6) Severe acid-base or electrolyte imbalance
(7) Hepatic compromise with coagulopathy

26
Q

What classes of drugs are implicated in neuroleptic malignancy syndrome?

A

(1) Neuroleptic Drugs (Anti-psychotics)

2) Anti-emitics (domperidone, metoclopromide, prochlorperazine

27
Q

What are the classic features of neuroleptic malignancy syndrome?

A

“FARM”
F - Fever > 38
A - Autonomic Sx - Tachycardia, labile BP, diaphoresis, arrhythmia
R - Rigidity - Classically lead pipe/cogwheel. M - Mental status changes - agitated, delirious, catatonic, coma

NO CLONUS - HYPOREFLEXIA

28
Q

What are the diagnostic criteria for serotonin syndrome (5)?

A

Hunter Criteria
Need to have an inciting serotonergic agent and at least one of:
(A) Spontaneous Clonus
(B) Ocular Clonus
(C) Inducible clonus + diaphoresis or agitation
(D) Tremor + Hyperreflexia
(E) Hypertonic + Temp > 38 + Ocular OR inducible clonus.

29
Q

What is the treatment for serotonin syndrome?

A

(1) Supportive AND
(2) Benzodiazepines

IF failure of benzodiazepines:
Cyprohepatdine

30
Q

What is the treatment for neuroleptic malignant syndrome?

A

(1) Supportive
(2) Benzodiazepines

If failure of benzodiazepines and supportive measures:
(A) Dantrolene
(B) Bromocriptine
Can be used as adjuncts.

31
Q

What is the benefit of balanced crystalloid (Ringer’s lactate) over normal saline?

A

Possibly increased risk of adverse kidney events with normal saline.

32
Q

What is the most common arrhythmia in digoxin toxicity?

A

Accelerated junctional tachycardia

33
Q

What are the characteristics of “dig effect” on ECG (4)?

A

(1) T-wave flattening/inversion
(2) QT shortening
(3) Scooped ST segments with ST depressions in the lateral leads.
(4) Increased amplitude of u waves.

34
Q

How would you manage digoxin toxicity?

A

(1) Dig level on arrival and six hours later.
(2) Continuous cardiac monitoring
(3) Activated charcoal if ingestion < 2 hours ago.
(4) Consider digifab antidote.

35
Q

What is different about the management of hyperkalemia in digoxin toxicity?

A

DO NOT give calcium.

36
Q

When would you consider giving digibind in the setting of digoxin toxicity?

A

(1) Life threatening or hemodynamically unstable arrhythmia.
(2) Hyperkalemia (> 5)
(3) Evidence of end organ failure (aLOC, AKI)
(4) Any dig level > 13 in acute or > 5.1 in chronic.
(5) Acute ingestion in adults > 10 mg

37
Q

What medication should you never use to treat refractory seizures in the setting of TCA overdose?

A

Dilantin —> Sodium channel blocker as well. Potentiates adverse cardiac effects of TCA.

38
Q

How do you treat carbon monoxide poisoning?

A

(1) 100% FiO2

IF carboxy-hemoglobin > 25% (or 20% if pregnant) then hyperbaric O2 is indicated

39
Q

What finding would suggest CO poisoning?

A

Normal finger probe oxygen saturation and PaO2 on ABG but O2 sat low on ABG.

40
Q

What metabolic abnormality results from cyanide poisoning?

A

Metabolic acidosis with anion gap and lactic acid, with equalization of arterial and venous O2 sats.

41
Q

What is the treatment for beta-blocker or calcium channel blocker overdose?

A

Glucagon

High-dose insulin with infusion of dextrose to maintain euglycemia.

42
Q

What is the treatment for organophosphate toxicity?

A

Atropine

43
Q

What is the treatment for cyanide poisoning?

A

(1) Hydroxycobalamin
(2) Amyl nitrite, sodium nitrite or thiosulfate
(3) Methylene blue (high dose, less effective treatment overall)

44
Q

What toxins might cause a cherry red appearance of the lips and skin?

A

Carbon monoxide and cyanide poisoning.

45
Q

What are the indications for hyperbaric oxygen in carbon monoxide poisoning (5)?

A

(1) COHb > 25% (20% if pregnant)
(2) pH < 7.1
(3) MI
(4) Loss of consciousness
(5) Fetal distress in pregnancy

46
Q

In which toxicity might you smell bitter almonds when examining a patient?

A

Cyanide poisoning

47
Q

What is the role of dialysis in CN poisoning?

A

No role

48
Q

What are the muscarinic features of organophosphate poisoning?

A 
“DUMBELS” 
D - Diaphoresis, Diarrhea
U - Urination
M - Miosis
B - Bronchospasm, bronchorrhea, bradycardia
E - Emesis
L - Lacrimation
S - Salivation
49
Q

Which toxic ingestion may result in delayed painful stocking and glove parasthesias, followed by flaccid weakness of the lower extremities?

A

Organophosphate poisoning

50
Q

Which substances can result in organophosphate poisoning?

A

(1) Insecticides
(2) Alzheimer’s Meds: Pyridostigmine, donepezil, edrophonium.
(3) Myasthenia Meds: Neostigmine
(4) MOAi

Critical Care & Toxicology (5 decks)

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