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Block 4: Intro to Clinical Toxicology


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Accidental poisonings account for what percentage of poisonings each year?
What portion of the population is most often accidentally poisoned?
If 90% of poisoning are accidental, what percentage is intentional?
What portions of the population make up the intentional poisonings?
adolescents and adults
95% of poisonings in children involve how many substances?
One substance
TRUE or FALSE: all adult poisonings are mixed ingestions.
FALSE-- 50% of adult poisonings are mixed
About what percentage of poisoning deaths are intentional?
About 50%
Those lethal intentional poisonings occur most often in what portion of the population?
These two classes of substances are the most commonly ingested substances.
1)Household cleaning substances
2)OTC analgesics
These two types of drugs are most commonly involved in fatal ingestions
2)analgesic drugs
Which two types of poisonings are frequently misdiagnosed (Hint: we're talking situational)?
TRUE or FALSE: only primary care and ER physicians deal with poisonings
FALSE: docs in many specialties encounter poisonings
TRUE or FALSE: understanding a general approach to the poisoned pt can improve clinical outsome significantly.
Name the six steps in the general approach to the poisoned pt.
1)pt stabilization
2)rapid pt eval
3)prevent reabsorption of toxic agent
4)enhance elimination of toxic agent
5)use specific antidote (where available)
6)supportive care
This type of assessment/therapy is paramount in initial phases of management
Basic Life Support (BLS)
Pts w/depressed levels of consciousness, including coma, get these four drugs
TRUE or FALSE: drug-induced seizures are easily controlled
What two aspects of respiration must be carefully assessed in the pt?
TRUE or FALSE: the history in drug overdose is quite reliable and your best source of info
FALSE: it's quite unreliable; seek ancillary info
TRUE or FALSE: the physical exam is extremely important for gathering key data.
HTN and tachycardia on PE may point to this illicit drug as cause of OD
Hyperpnea and elevated temp suggest this as a cause of OD
Salicylate poisoning
Anticholinergic poisoning may cause your skin to become *what* and *what*?
Warm and Dry
This physical finding may suggest methemoglobinemia or hypoxia.
Needle tracks in a comatose pt may suggest what type of overdose?
Narcotic overdose
Miosis may be see with what two types of agonists?
Opiate and Cholinergic agonists
Mydriasis may be seen with what two types of agents?
Sympathomimetic or Anticholinergic agents
Combined vertical and horizontal nystagmus are seen with OD on what drug?
A bitter almond smell on the pt's breath points to *what* as the cause of poisoning?
Chemical burns visible in the oral cavity suggest what?
Ingestion of caustic substances (drano, anyone?)
Tachycardia and an unexpected S3 gallop suggest heart failure from what what type of OD?
OD on negative inotropic agents (Ca2+ channel- or beta-blocking drugs)
Narcotic, antimuscarinic and sedative poisonings cause what type of bowel sounds?
hypoactive bowel sounds
Organophosphate and theophylline poisoning cause what type of bowel sounds?
hyperactive bowel sounds
Toxic or metabolic encephalopathy are suggested by neuro findings in what type of distribution?
Symmetric distribution
Increased muscle tone is seen when you OD on what type of drug?
Sympathomimetic drugs
Tremor, seizures and brisk reflexes are seen when pts OD on these two drugs
Lithium and theophylline
Ataxia, dysarthria and nystagmus are seen if you overdose on these three drugs.
3)sedative hypnotics
What are the four main toxic syndromes?
Mild hypotension, bradycardia, hypoventilation, lethargy and miosis suggest which toxic syndrome?
Narcotic syndrome
TRUE or FALSE: you should delay tx while waiting for the labs on your poisoned pt; you don't want to treat something that's not there!.
Name 7 drugs for which there is rapid, direct quantitation (pnemonic: I SALTED)
Serum bicarb less than what concentration indicates metabolic acidosis?
18 meq/L
How do you confirm metabolic acidosis?
Measure arterial pH
What is the formula for the anion gap?
AG = [(Na)-(HCO3)+(Cl)]
What is the normal value for the anion gap?
12 plus or minus 2
Break down the causes for metabolic acidosis given by the pneumonic AT MUD PILES
5)Diabetic Ketoacidosis
8)Lactic Acid
9)Ethylene Glycol
Drug-induced pulmonary edema or drug-induced lung injury may cause what finding on arterial blood gas?
Respiratory depression (which is common with any sedating toxin) can cause what finding on ABG?
These two findings on ABG can be primary respiratory or metabolic and are commonly found in poisoned pts
Acidemia or alkalemia
Certain toxic agents are osmotically active in plasma and can be inferred by determining what?
the osmolar gap
How do you calculate the calculated serum osmolarity?
CSO = (2xNa)+(Glucose mg/dL / 18)+(BUN mg/dL / 2.8)
How do you calculate the osmolar gap?
OG = measured serum osmolarity - calculated serum osmolarity
Normally, the osmolar gap is what value?
Zero (<10 is still considered normal)
Significant osmolar gaps are seen in poisoning with what four substances (hint: all the same type)?
3)ethylene glycol
Prolonged QRS duration suggests OD on what type of med?
Intact capsules of this mineral can be visualized on plain films of the abdomen.
This is the preferred emetic agent.
Syrup of Ipecac
What are the four contraindications for use of Syrup of Ipecac?
1)ingestion of corrosive substances
2)pt age < 6 mos
3)absent gag reflex
What is the most important consideration in the performance of gastric lavage?
Protection of the airway
When is gastric lavage most useful?
Recent (within 1 hour) ingestion in which emesis cannot be performed
What is the contraindication for gastric lavage?
Ingestion of corrosive substances
This is the recommended tx for practically all ingestions.
Activated charcoal
How do you dose activated charcoal?
1-2 gm/kg body weight
A cathartic (like sorbitol or magnesium citrate) should be administered when in relation to giving the charcoal?
Administered with or immediately after charcoal
TRUE or FALSE: if a pt has had a dermal exposure, you should leave on all contaminated clothing to avoid spreading the substance.
FALSE: contaminated clothing should be removed and properly secured
How do you treat an eye exposure?
Immediate copious irrigation with saline
Ophthalmology consult is required in what two cases?
1)caustic exposure
2)complaints of double vision
Renal elimination of weak acids is greatly increased by alkalinizing urine (pH=8) by giving what?
Sodium bicarb
Alkalinizing the urine is particularly helpful when?
Mild-to-moderate salicylate intoxication.
Poisoning with toxins with high water solubility, low volume of distribution, low molecular weight (<500) and low protein binding can be treated how?
This detox technique is more effective than hemodialysis for lipid soluble, high-weight poisons with a low volume of distribution.
What *is* hemodialysis?
blood dialyzed extracorporeally through permeable membranes against electrolyte solutions
What *is* hemoperfusion?
blood filtered extra-corporeally through a cartridge containing activated charcoal or resin
Hemoperfusion is used most commonly in intoxication with what drug?
This is a frequent adverse effect associated with hemoperfusion.
This method of poison removal is good for drugs that undergo enterohepatic circulation and a few that don't
Serial oral activated charcoal
How do you dose serial oral activated charcoal?
0.5 gm/Kg every 2-4 hours
Serial oral activated charcoal is particularly good for poisoning with which three drugs?
Which two procedures are only employed in severe poisonings of infants?
1)plasma exchange
2)exchange transfusion
Fab fragments to digoxin are the prototype in this antidote category
Immunologic antidotes
How do the Fab fragments work?
They bind digoxin and the compound gets filtered by the kidney. This causes a marked reduction in toxicity followed by greatly increased elimination
This type of antidote is used to treat pts intoxicated with lead, iron, arsenic, gold, copper and mercury.
Chelator antidotes
These agents exert pharmacologic actions which oppose those of the poison; also, agents that compete for receptors that mediate toxic actions
Pharmacologic antidotes
Give two examples of pharmacologic antidotes
1)atropine for organophosphate poisoning
2)isoproterenol for beta-blocker overdose
These agents provide substrates for detox of reactive intermediates or that compete for enzymes that create toxic metabolites
Biochemical agents
Name two biochemical antidotes
2)4-methylpyrazole for ethylene glycol
What is the final phase in the management of the poisoned pt?
Supportive care and observation
In the poisoned pt, special attention should be paid to what three aspects of ICU care?
TRUE or FALSE: cardiac monitoring and frequent lab assessments are done initially.
You should anticipate what ICU complication in your poisoned pt?
Aspiration pneumonia
You should frequently reassess what in your poisoned pt in the ICU?
fluid and electrolyte status
TRUE or FALSE: formal psych eval is required for all pts who have attempted suicide before removing them from a one-to-one nursing setting.

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