USMLE Step 3 - Emergency Medicine/Toxicologytony_a_martinez

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- What drugs do you want to give when you have a pt with Acute mental status change of unclear etiology?
- What else will you give?
- Naloxone, dextrose, thiamine
- Then oxygen & saline
- Also check toxicology screen
When is gastric emptying useful?
Only useful in the 1st hour after an overdose

1 hour: 50 percent of pills can be removed
1-2 hours: 15 percent of pills can be removed
2 hours: Useless
When is gastric emptying contraindicated?
When caustics (acids and alkalis) have been ingested.
When can intubation and lavage be performed?
Only if the patient has ingested the substance within 1-2 hours and there is no response to naloxone, dextrose, and thiamine.
If you have a toxicology case and don't know what you should give, then give __________.
Charcoal (it won't do any harm)
What should you order on the first CCS screen if you have a pt with an overdose?
1) Specific antidote (if clear)
2) Toxicology screen
3) Charcoal
4) CBC, Basic Metabolic Profile, urinalysis
5) Pyschiatry consultation if overdose is the result of suicide attempt
6) Oxygen if suspected Carbon Monoxide Poisoning or any dyspneic patient
Antidote for Acetaminophen
N-acetyl cysteine
Antidote for Aspirin
Bicarbonate to alkalinize the urine
Antidote for benzo overdose
- Let the patient sleep
- Do not give flumazenil - may precipitate seizures
Antidote for carbon monoxide
100% oxygen,
hyperbaric in some cases
Antidote for digoxin
Digoxin binding antibodies (Digibind) for severe disease (CNS and cardiac abnormalities)
Antidote for ethylene glycol
Fomepizole or ethanol
Antidote for methanol
Fomepizole or ethanol
Antidote for methemoglobinemia
Methylene blue
Antidote for Neuroleptic malignant syndrome
Dantrolene
Bromocriptine
Cabergoline
Antidote for organophosphates
Atropine + pralidoxime
Antidote for TCAs
Bicarbonate (for cardiac protection) =>>>>> if ECG shows widened QRS
What is the time course of developing hepatic failure after acetaminophen ingestion?
First 24 hours: Nausea & Vomiting which resolve

48-72 hours later: Hepatic failure
How long after the ingestion of acetaminophen is NAC effective?
Up to 24 hours after ingestion.
After that there is no specific therapy to treat or prevent liver toxicity
What amounts of acetaminophen are toxic?
What amounts are generally fatal?
10 g = toxic
15 g = fatal

(these values are lower if there is underlying liver damage or if the pt has alcohol abuse)
If the amount of acetaminophen ingestion is equivocal then what is the next step?
Get an acetaminophen level to determine if there will be toxicity.
If the amount of acetaminophen ingestion is large then what is the next step?
Donot wait for the results of acetaminiophen level to give NAC as untreated acetaminophen overdose will kill the patient
"Extra NAC never hurt anyone"
NAC is benign
Aspirin overdose features?
- First there is Respiratory Alkalosis (Direct stimulation of the brainstem =>>> Hyperventilation)
- Followed by Metabolic Acidosis (Loss of Krebs cycle in mitochondria=>>Hypoxia=>>Lactic Acidosis with elevated anion gap)
- Renal insufficiency - Salicylates like other NSAIDs are directly toxic to kidney tubule
- Elevated prothrombin time - ASA interferes with the production of vitamin K dependent clotting factors
- CNS: Confusion. Severe cases lead to Coma and Seizures
- Fever
What should you order on CCS if you suspect Aspirin overdose?
1. CBC
2. Chemistry Panel
3. ABG
4. PT/INR/PTT
5. Salicylate (ASA) level
What should you give for treatment of ASA overdose?
1) Bicarbonate (Alkalinize the urine to increase excretion)
2) Charcoal (to block absorption)
3) Dialysis (is used for severe cases)
Easiest way to identify the aspirin overdose patient?
Tinnitus
Drugs overdoses in which you should alkalinize the urine?
1) Salicylates (ASA)
2) Tricyclic Antidepressants (TCAs)
3) Phenobarbital
4) Chlorpropamide
What should you do with a Patient with benzodiazepine overdose on CCS?
- Move the clock forward and let the pt sleep.
- Donot administer Flumazenil for benzodiazepine overdoses as you donot know who has chronic dependency and flumazenil can induce benzodiazepine withdrawl and seizures
60 percent of deaths in the first 24 hours after a fire are due to
carbon monoxide poisoning.
CO poisoning presents with ?
1) Shortness of Breath
2) Headache, Lightheadedness
3) Disorientation
4) Fatigue
5) Severe disease causes metabolic acidosis from tissue hypoxia
Family is "snowed in" and has been heating their house with a wood-burning stove. What are you worried about?
CO poisoning.
What treatment should you give to all survivors of a fire?
100 percent oxygen until you know their CO levels
Most common symptom of digoxin overdose?
GI disturbance
- Nausea
- Vomiting
- Diarrhea
- Pain
Other symptoms assocaited with digoxin toxicity?
- Yellow halos around objects and blurred vision
- Arrhythmia (PR prolongation, paroxysmal atrial tachycardia with block)
- Encephalopathy
______kalemia leads to digoxin toxicity, but digoxin toxicity leads to _______kalemia.
Hypokalemia leads to digoxin toxicity, but digoxin toxicity leads to hyperkalemia.
What is the difference between ethylene glycol and methanol overdoses?
Both present with intoxication and Increased anion gap metabolic acidosis
Ethylene glycol presents with:-
- Renal insufficiency from direct toxicity
- Hypocalcemia from precipitation of the oxalic acid with calcium
- Kidney stones
Methanol presents with:-
- Visual disturbances
- Retinal hyperemia from the toxicity of the formic acid.
What are the treatments for ethylene glycol and methanol poisoning?
- Ethanol or fomepizole
- Dialysis to remove them from body before they are metabolized into the toxic metabolite.
Pt is cyanotic with a normal pO2, what are you thinking of?
Methemoglobinemia.
Presenting symptoms of methemoglobinemia?
1) CNS: Brain (Confusion, dizziness, Headache, seizures)
2) Respiratory: (Shortness of breath)
3) Skin: (Cyanosis)
What in the History will make you concerned about methemoglobinemia?
- History of use of nitrate, anesthetics, dapsone, or other oxidants as well as any drug ending in -CAINE (lidocaine, benzocaine, bupivacaine)
- Nitrogylcerin can also be the cause
Methemoglobulinemia. Diagnostic testing?
- Normal pO2 on ABG with chocolate-brownish blood (Oxidized Blood)
- Methemoglobin level
What is the treatment for methemoglobulinemia?
- 100% oxygen
- Methylene blue (restores hemoglobin to its normal state)
Features of Neuroleptic Malignant Syndrome
- History of ingestion of Neuroleptic medication such as Phenothiazines (Antipsychotic drugs)
- Muscle Rigidity
- High temperature
- Confusion
- Arrhythmia
- Hyperkalemia
How Malignant Hyperthermia differs from Neuroleptic Malignant Syndrome?
- Same symptoms
- Malignant Hyperthermia caused by Anesthetics
- Neuroleptic Malignant Syndrome caused by Antipsychotics
Features of heat stroke? Treatment?
Features:-
1. Dry skin
2. Altered mental status
3. Elevated body temperature
Treatment:-
Spraying patient with water, fanning the patient in an air conditioned room or using ice baths/packs
What should you NOT use to treat heat stroke?
DONOT infuse iced saline into the body- it can stop the heart
Compare and contrast the treatments:-
- Neuroleptic Malignant Syndrome
- Malignant hyperthermia
- Heat stroke
- NMS - Bromocriptine, dantrolene
- Malignant hyperthermia - Dantrolene
- Heat stroke => Hydration and external cooling
Organophosphates Poisoning. Features?
Organophosphates inhibit acetylcholinesterases, thus increasing the effect of the acetylcholine.
Features:-
DUMBELLS
Diarrhea, Diaphoresis
increases Urination
Miosis
Bradycadia, wheezing from Bronchospasm
Emesis
Lacrimation Salivation
Organophosphate overdose.
Best initial therapy?
Most effective therapy?
What other non-medical thing should you do?
- Best initial: Atropine
- Most effective: pralidoxime
- Remove the pt's clothes and wash the rest off the the patient
Death in Tricyclic Antidepressant overdose occurs from what 2 things?
What are other symptoms of TCA overdose?
- Seizures
- Arrhythmias
Other Symptoms:-
Symptoms occure due to anticholinergic properties:
- Dilated pupils
- Dry mouth
- Constipation
- Urinary retention
What is the most urgent thing to order when suspecting a TCA overdose?
- EKG to look for QRS widening.
- If there is QRS widening, give bicarbonate and transfer to the ICU.
What are the presenting symptoms of a Black Widow Spider bite?
1) Abdominal pain
2) Hypocalcemia
3) Rigidity
What do you treat a black widow bite with?
antivenin
Features of Brown Recluse spider bite?
- Local necrosis
- Bullae
- Dark lesions.
How do you treat the lesion of a brown recluse spider bite?
- Debridement of the wound
- Occasionally steroids and dapsone are of benefit
Management of Burns?
- Most important step when a patient has been in a fire is to give 100% Oxygen as most common cause of death in fires in CO poisoning
- Then important thing is to determine who needs to be intubated and who can be managed just with fluids
Intubate any pt with burns if ?
Following symptoms are present
1) Hoarseness
2) Wheezing
3) Stridor
4) Burns inside nose or mouth
If there is no evidence of respiratory injury in the presence of burns, then what is the most important treatment?
- Give fluids.
4 ml of Lactated Ringer's or Normal Saline for
- each percentage with a 2nd or 3rd degree burn for
- each kilogram.
What is the most common cause of late death from burns?
infection
Most common abnormality on EKG with hypothermia?
Hypothermia kills with??
- Osborn J waves (look like ST segment elevation)
- Hypothermia kills with rhythm disturbance
What is does osborne J wave look like
Osborn waves are positive deflections occurring at the junction between the QRS complex and the ST segment
How does acute angle closure glaucoma present?
Ophthalmologic Emergency
1) Fixed midpoint pupil
2) Red eye
Acute angle closure glaucoma.
Best initial therapy?
Other treatment?
Best initial therapy:- Pilocarpine drops to constrict the pupil.
Other treatment:-
1) Mannitol can be used as a osmotic diuretic to help open the angle
2) Acetazolamide decreases the production of aqueous humor
3) Prostaglandin analogs (Latanoprost, Travoprost)
4) Beta blockers topically (Timolol)
5) Alpha agonists (Apraclonidine)
Sudden loss of vision like "a curtain coming down".
Diagnosis?
What should you do on CCS?
Retinal detachment.
1) Consult opthalmology
2) Perform a dilated retinal exam
Retinal Detachment.
Treatment?
- Tilt the head back
- Reattach the retina with surgery, cryotherapy or by injecting an expansile gas into the eye
If these fail then
- Place a band around the eye to get the retina close to the sclera
Differential Diagnois for Red Eye?
- Acute Angle Closure Glaucoma
- Conjunctivitis
- Uveitis
- Abrasion
Viral Conjunctivitis vs Bacterial Conjunctivitis?
Viral:-
- Bilateral watery discharge
- Itchy eyes
Bacterial:-
- Unilateral purulent discharge
- Eyelids stuck together
- Bacterial form treated with Topical antibiotics
Uveitis.
Presentation?
Diagnosis?
Treatment?
- Red Eye + Photophobia
- Diagnosis by Slit Lamp examination
- Treatment: Steroids
Abrasion
Presentation?
Diagnosis?
Treatment?
- Red eye + hx of trauma + Contact lens wearer
- Diagnosis: Fluorescein stain picks up on damaged cornea
- Treatment: No specific therapy. Donot patch abrasions caused by contact lens
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