Tox: Decontamination Flashcards
4 primary methods of gastric decontamination
1) WBI
2) Gastric lavage
3) Activated charcoal
4) Induced emesis
How is induced emesis performed
using syrup of ipecac
Indications for induced emesis
Essentially none.
Indications for gastric lavage
1) Ingestion of substance with high-toxic potential
2) Present w/in 1hr ingestion
3) Ingested substance not bound by AC or has no effective antidote
4) Benefits outweigh risks
Contraindications for gastric lavage
1) spontaneous emesis
2) Diminished LOC/unprotected airway
3) Ingestion of hydrocarbons, caustics or FB
4) Pt is high risk for esophageal or gastric injury (GI hemorrhage, recent Sx, etc)
Technique for gastric lavage
1) 36-40F tube for adults, 22-28F tube for children.
2) Position pt LL decubitus with head lowered below feet.
3) Aspirate stomach contents
4) Lavage with 250cc aliquots warm H2O. Continue until fluid is clear and minimum of 2L used.
5) Instill AC after as indicated
Potential complications with gastric lavage
1) Vomiting/aspiration
2) Esophageal injury or perforation
Dose of activated charcoal
1) Should be given in 10:1 ratio (1g poison -> 10g AC)
2) Empiric dosing is 50-100g AC (1g/kg in kids)
Indications for AC
1) w/in 1 hr ingestion
2) Potentially dangerous amt of poison that is adsorbed by AC
When should MDAC be considered?
For agents that undergo enterohepatic or enteroenteric recirculation (e.g. carbamazepine, quinine, phenobarb).
Substances for which AC is contraindicated
Metals (e.g. iron, lead, lithium), hydrocarbons, alcohols, caustics
Contraindications to AC
1) Substance is poorly adsorbed by AC
or presents greater danger if AC induces vomiting (e.g. caustics, hydrocarbons).
2) Airway unprotected
3) Pt presents >2 hrs post ingestion
4) Cases where endoscopy may be indicated or if pt is at risk of hemorrhage/perforation (e.g. caustics)
When might AC still be indicated despite ingestion occurring >2hrs prior to presentation?
1) Ingestion of massive quantities
2) SR products
3) part of MDAC strategy
Risks of AC
vomiting/aspiration
MOA of WBI
Flushes GI tract to decrease transit time of luminal contents, thereby limiting absorption.
Dose of PEG in WBI
Administer PEG at rate of 1-2L/hr with end point of clear rectal effluent OR total irrigation volume of 10L
Indications for WBI
1) Removal of ingested drug packets (e.g. body packers) without suspicion of packet rupture.
2) Large ingestion of SR product
3) Toxic ingestion of agent not adsorbed by AC (e.g. metals)
Most common indications for WBI: body packers, metals, SR medications
Contraindications to WBI
1) Unprotected airway
2) Reduced GI motility
3) Bowel obstruction
4) Significant GI hemorrhage
5) Persistent emesis
Endpoint for WBI
clear rectal effluent or total irrigation volume >/10L
Complications of WBI
1) vomiting/aspiration
2) Patient discomfort (bloating, flatulence, cramping)
(should NOT cause significant electrolyte abnormalities)
3 methods of enhanced elimination
1) MDAC
2) Urinary alkalinization
3) Hemodialysis
MOA MDAC
Uses repeated doses of AC (q2-4h) to increase poison clearance.
Exerts effects through disruption of enterohepatic circulation or direct adsorption across the GI mucosal surface (‘gut dialysis’)
Indications for MDAC
1) Drugs with enterohepatic or entero-entero circulation
2) SR products
3) Agents that form concretions or bezoars (e.g. carbamazepine, dapsone, quinine, phenobarb)
Contraindications to MDAC
1) Unprotected airway
2) GI obstruction or ileus
3) GI tract not anatomically intact
Compared to AC, what are patients that receive MDAC at greater risk of?
Bowel obstruction
Examples of drugs where MDAC may be indicated
Carbamazepine, dapsone, phenobarb, quinines, theophylline
Examples of drugs where urinary alkalinization may be indicated
1) Aspirin/salicylates
2) Methotrexate
3) Phenobarbital
Examples of drugs where HD may be indicated
MMELS: metformin, methanol, ethylene glycol, lithium, salicylates (most common).
Properties that make a toxin amenable to hemodialysis
LMW, low plasma protein binding, small volume of distribution, poor endogenous clearance.
Alt, may be indicated if severe acidosis is ppt’d by drug.
Difference in fundamental mxn between single dose and multidose AC
Single dose is used to decrease poison absorption.
Multiple dose is used to increase poison elimination
Why won’t urinary alkalinization work in hypokalemic patients?
Renal tubules will reabsorb K+ ions in exchange for hydrogen ions, prevent alkalinization
MOA of urinary alkalinization
Increases renal elimination of a drug via ion trapping.
How to alkalinize urine
Start with: 150 mEq NaHCO3 (3 amps) in 1L D5W, infuse at 1.5-2x maintenance IVF rate. Give K+ as indicated.
Main risk with urinary alkalinization
Fluid overload due to high rate and large amount of Na+
