Toxicology Flashcards
1
Q
Initial eval of pt presenting w/ overdose?
A
- ABCs
- ABGs
- IV access
- tx coma promptly:
glucose,narcan, if ETOHism suspected: thiamine - maintain circ: crystalloid, if that doesnt work: swan to check PCWP (worry about over hydration and pulm edema)
- tx seizures: diazepam, if fails: phenobarbital
- cardiac monitoring and pulse Ox
2
Q
Triad of opioid overdose?
A
- CNS depression
- miosis
- respiratory depression
3
Q
When should emesis be induced?
A
- only in pts w/ intact gag reflex
- may have limited efficacy if more than 1 hr since ingestion
- most useful if initiated at home w/in few minutes of ingestion
- not indicated in ED for drugs not absorbed by charcoal (iron, lithium)
- don’t induce emesis if caustics or low viscosity hydrocarbons have been ingested
- don’t induce if rapid acting convulsants have been ingested (amphetamine, cocaine, TCAs, strychnine)
- ipecac syrup 30 ml for adults, 15 ml for kids followed by 1-2 liters of water until they vomit
4
Q
When is a gastric lavage done?
A
- suspected serious ingestions when emesis has failed
- pt is lethargic or otherwise uncooperative
- when gag reflexed is markedly depressed
- pts have ingested rapid acting convulsants
- place pt in L lateral decubitus position w/ head down (protect airway)
- use large bore NG or OG tube at least 36Fr
- use tap water or saline at body temp in 250ml increments and continue until fluid returns clear and free of pil fragments
5
Q
Use of activated charcoal in decontamination?
A
- following emesis or lavage give 50-100g charcoal as slurry by mixing w/ equal amts of water
- can give b/f or after lavage/emesis: however need residual charcoal left in gut
- mix charcoal w/ sorbitol to improve taste and cathartic action
- charcoal has great adsorptive properties and binds most poisions (EXCEPT: potassium, alcohols, iron, lithium - PAIL)
- if ingested dose of poison known- give at least 10x that wt in activated charcoal
6
Q
When is whole bowel irrigation useful?
A
- w/ sustained release and enteric coated tabs
- golytely 1-2 L/hr until rectal effluent is clear
7
Q
Lab studies for toxicology?
A
- ABGs
- draw blood for chem 7 and calc anion and osmolar gap
- obtain EKG and monitor for wide QRS or prolonged QT
- CXR looking for pulmonary edema
- flat plate of abdomen looking for radiopaque pills (high false neg)
- urine for tox screen
- draw and hold serum tox screens
8
Q
1st order kinetics?
A
- fixed percentage of toxin is removed per unit time (barbs)
9
Q
zero order kinetics?
A
- fixed amt of toxin removed per unit time (alcohol)
- many times in OD situations - elimination pathways are saturated and drug which normally has 1st order kinetics develops zero order
10
Q
toxins w/ large volumes of distribution (tissue bound not plasma bound) are not efficiently removed by?
A
- dialysis or diuresis
11
Q
Use of hemodialysis?
A
- toxin must be relatively water soluble and not protein bound
- toxin is removed from blood into dialysate soln across semipermeable membrane
- drugs need to have small vol of distribution and slow rate of intrinsic clearance
- indicated for: MELS - methanol, ethylene glycol, lithium, and salicylate
12
Q
When is hemoperfusion preferred?
A
- advantage over hemodialysis: drug or toxin is in direct contact w/ adsorbent material - quick, can be used w/ activated charcoal
- drugs need to have small vol of distribution and slow rate of intrinsic clearance
- high MW, poor water solubility, plasma binding proteins not limited factors
- commonly assoc w/ thrombocytopenia and won’t correct lyte imbalances, or adjust pH
13
Q
Hemoperfusion is useful for what drugs?
A
TRI PEP-TD
- Tricyc antidepressants
- paraquat
- ethchlorvynol
- phenobarbital
- theophylline
- digitoxin
14
Q
Antidotes for common ODs?
A
- APAP: acetylcysteine
- anticholinergics: physostigmine (also tx myasthenia gravis)
- benzos: Flumazenil (danger - can cause seizures, is a GABA antagonist)
- cyanide: Na nitrate and Na thiosulfate
- methanol/polyeth glycol (antifreeze): ethanol
- narcotics: naloxone
15
Q
Most common cause of change in osmolar gap?
A
- ethanol
16
Q
What occurs in APAP overdose?
A
- active ingredient in many OTC preps
- tylenol w/ mixed ODs (lortab, vicodin, darvocet)
- one of metabolites are very hepatotoxic:
saturates glutathione detoxification system, accum in liver and causes delayed hepatotoxicity 24-72 hrs post ingestion - toxic dose is over 140 mg/kg (lower in pt w/ chronic liver disease, or alcoholism)
- draw up an APAP level
17
Q
Tx of APAP overdose?
A
- decontaminate and give activated charcoal
- est severity:
amt ingested, best level is 4 hrs post ingestion - ***acetylcysteine therapy:
subs for glutathione and binds to metabolite - 140 mg/kg orally of 10-20% soln and follow up w/ 70 mg/kg dose q 4-8 hrs or until tylenol level is 0
- key: must be given EARLY - don’t wait for initialy level, must be given w/in 12-16 but preferably w/in 8-10 hrs
18
Q
Effects of cocaine/amphetamines?
A
- all are CNS stim and cause sympathetic hyperactivity
- some may produce sig vasoconstriction and cause HTN and bradycardia
- HTN may be accompanied by ventricular arrhythmias
- seizure and hyperthermia may produce rhabdo and myoglobinuria
19
Q
Sxs of cocaine overdoses?
A
- euphoria
- excitement
- restlessness
- toxic psychosis
- seizures
- HTN
- tachycardia
- hyperthermia
- possible MI (prinzmental angina)
20
Q
Dx and Tx of cocaine/amphetamine overdose?
A
- dx: sig toxicity will always have sxs, short half lives and peak effects occur w/in 12 hrs
-tx:
GI decontamination as indicated, severe agitation or psychosis: diazepam - tx seizures, if DBP over 120 or HTN encephalopathy: nitroprusside - if tachycardia/vent arrhythmias: BBs
- monitor temp and EKG - may need CT of head
- don’t acidify urine: myogloburia and ARF (rhabdo)
