Poisoning & Environ Exposures Flashcards
Chronic mercury toxicity
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
Acquired methemoglobinemia
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
acute opioid intoxication
classic triad: decreased RR, constricted pupils and depressed mental status; will see hypothermia, hypotension and decreased tidal volume on physical examination
Exposure to ionizing radiation
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
Niacin (vitamin B3) toxicity
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
Anticholinergic toxicity
anticholinergic agents competitively bind Ach at the muscarininc AchR; these can be reversed by cholinesterase inhibitors (ex: physostigmine)
Complications of lead poisoning in children
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
Arsenic poisoning
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
Nonexertional heat stroke (NHS)
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
Acute salicylate intoxication
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
Amatoxins
found in a variety of poisonous mushrooms and are potent inhibitors of RNA polymerase II - halting mRNA synthesis
Exercise-associated collapse (EAC)
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
Nitroprusside OD
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
Common toxicities and antidotes
Benzodiazepine OD
Flumazenil is a benzodiazepine receptor antagonist; it can reverse the sedative effects
Heat-related illnesses in elderly pts
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
Lead toxicity inhibition
Lead directly inhibits ferrochelatase and ALA dehydrogenase, resulting in anemia, ALA accumulation and elevated zinc protoporphyrin levels
Organophosphates
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
Organophosphate poisoning
Naloxone
a short-acting (<1hr) opioid antagonist used for the tx of opioid OD; but frequently requires redosing to prevent recurrent OD symptoms
Serotonin syndrome
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
Theophylline intoxication
seizures are the major cause of morbidity and mortality in OD; tachyarrhythmias are the other major concern
Beta blocker poisoning
competitive antagonists for endogenous catecholamines toxicity presents w hypotension, bradycardia, bronchospasm, and hypoglycemia
