Poisoning & Environ Exposures

Question 1

Chronic mercury toxicity

Answer 1

mercury impairs the breakdown of catecholamines, and toxicity can lead to excessive stimulation of the SNS (tachycardia, HTN, diaphoresis); desquamating hypersensitivity rash can also occur and deposition in the CNS can result in personality changes, insomnia and tremor

Question 2

Acquired methemoglobinemia

Answer 2

can be precipitated by benzocaine and result in conversion of Fe2+ to Fe3+ resulting in functional anemia and a left shift; pts have cyanosis that does not improve w supplemental O2

Question 3

acute opioid intoxication

Answer 3

classic triad: decreased RR, constricted pupils and depressed mental status; will see hypothermia, hypotension and decreased tidal volume on physical examination

Question 4

Exposure to ionizing radiation

Answer 4

induces DNA damage that predominatelyaffects highly proliferative cells (skin stem cells, hematogenous progenitors, intestinal crypt cells); rapidly dividing cells are the first to be lost resulting in hair loss, pancytopenia, diarrhea and n/v

Question 5

Niacin (vitamin B3) toxicity

Answer 5

the precursor for NAD and NADP; toxicity leads to increased PGE production which causes cutaneous vasodilation, flushing and pruritus that may be avoided by pretreating with NSAIDs

Question 6

Anticholinergic toxicity

Answer 6

anticholinergic agents competitively bind Ach at the muscarininc AchR; these can be reversed by cholinesterase inhibitors (ex: physostigmine)

Question 7

Complications of lead poisoning in children

Answer 7

lead poisoning can cause neurological, GI, renal and hematologic complications; symptoms can be vague but should be suspected if symptoms arise while residing in a home built before 1978; diagnosis is made by measuring the pt blood lead level

Question 8

Arsenic poisoning

Answer 8

impairs cellular respiration and presents w abdominal pain, vomiting, diarrhea, hypotension and a *garlic odor on the breath; insecticides and contaminated water are common sources of arsenic; Dimercaprol is the chelating agent of choice

Question 9

Nonexertional heat stroke (NHS)

Answer 9

a life-threatening disorder characterized by hyperthermia (104 F) associated w CNS dysfxn; anticholinergic meds promote heat stroke by impairing diaphoresis; other medications associated w NHS include sympathomimetics, dopamine antagonists, diuretics and beta blockers

Question 10

Acute salicylate intoxication

Answer 10

triad: fever, tinnitus and tachypnea; salicylates both stimulate respiratory drive to cause primary respiratory alkalosis and disrupt cellular metabolism to cause primary anion gap metabolic acidosis; toxicity classically presents w a mixed acid-base disturbance and a blood pH within normal range

Question 11

Amatoxins

Answer 11

found in a variety of poisonous mushrooms and are potent inhibitors of RNA polymerase II - halting mRNA synthesis

Question 12

Exercise-associated collapse (EAC)

Answer 12

typically occurs after intense exercise in well-conditioned athletes; characterized by loss of postural tone or syncope immediately following cessation of exercise and occurs due to impaired venous return to the heart

Question 13

Nitroprusside OD

Answer 13

cyanide toxicity is an important adverse effect of nitroprusside; blockage of the ETC leads to impaired oxygen utilization, causing lactic acidosis, neurological dysfunction and CV collapse

Question 14

Common toxicities and antidotes

Answer 14

Question 15

Benzodiazepine OD

Answer 15

Flumazenil is a benzodiazepine receptor antagonist; it can reverse the sedative effects

Question 16

Heat-related illnesses in elderly pts

Answer 16

are at increased risk due to several features of normal aging that impair normal thermoregulatory mechanisms, including tonic contraction of the peripheral vasculature, reduced sweat gland density and reduced effective epidermal area available for heat transfer

Question 17

Lead toxicity inhibition

Answer 17

Lead directly inhibits ferrochelatase and ALA dehydrogenase, resulting in anemia, ALA accumulation and elevated zinc protoporphyrin levels

Question 18

Organophosphates

Answer 18

inhibit acetylcholinesterase inhibitors, leading to muscarininc and nicotinic cholinergic hyper stimulation; management includes atropine, a competitiveinhibots of Ach followed by pralidoxime, a cholinesterase-reactivating agent

Question 19

Organophosphate poisoning

Answer 19

Question 20

Naloxone

Answer 20

a short-acting (<1hr) opioid antagonist used for the tx of opioid OD; but frequently requires redosing to prevent recurrent OD symptoms

Question 21

Serotonin syndrome

Answer 21

altered mental status, autonomic hyperactivity and neuromuscular excitation; causes include high doses and/or combinations of serotonergic drugs; tryptophan is a precursor for serotonin; cyproheptadine is an antidote

Question 22

Theophylline intoxication

Answer 22

seizures are the major cause of morbidity and mortality in OD; tachyarrhythmias are the other major concern

Question 23

Beta blocker poisoning

Answer 23

competitive antagonists for endogenous catecholamines toxicity presents w hypotension, bradycardia, bronchospasm, and hypoglycemia