Tox: Decontamination

Question 1

4 primary methods of gastric decontamination

Answer 1

1) WBI
2) Gastric lavage
3) Activated charcoal
4) Induced emesis

Question 2

How is induced emesis performed

Answer 2

using syrup of ipecac

Question 3

Indications for induced emesis

Answer 3

Essentially none.

Question 4

Indications for gastric lavage

Answer 4

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

Question 5

Contraindications for gastric lavage

Answer 5

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)

Question 6

Technique for gastric lavage

Answer 6

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

Question 7

Potential complications with gastric lavage

Answer 7

1) Vomiting/aspiration

2) Esophageal injury or perforation

Question 8

Dose of activated charcoal

Answer 8

1) Should be given in 10:1 ratio (1g poison -> 10g AC)

2) Empiric dosing is 50-100g AC (1g/kg in kids)

Question 9

Indications for AC

Answer 9

1) w/in 1 hr ingestion

2) Potentially dangerous amt of poison that is adsorbed by AC

Question 10

When should MDAC be considered?

Answer 10

For agents that undergo enterohepatic or enteroenteric recirculation (e.g. carbamazepine, quinine, phenobarb).

Question 11

Substances for which AC is contraindicated

Answer 11

Metals (e.g. iron, lead, lithium), hydrocarbons, alcohols, caustics

Question 12

Contraindications to AC

Answer 12

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)

Question 13

When might AC still be indicated despite ingestion occurring >2hrs prior to presentation?

Answer 13

1) Ingestion of massive quantities
2) SR products
3) part of MDAC strategy

Question 14

Risks of AC

Answer 14

vomiting/aspiration

Question 15

MOA of WBI

Answer 15

Flushes GI tract to decrease transit time of luminal contents, thereby limiting absorption.

Question 16

Dose of PEG in WBI

Answer 16

Administer PEG at rate of 1-2L/hr with end point of clear rectal effluent OR total irrigation volume of 10L

Question 17

Indications for WBI

Answer 17

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

Question 18

Contraindications to WBI

Answer 18

1) Unprotected airway
2) Reduced GI motility
3) Bowel obstruction
4) Significant GI hemorrhage
5) Persistent emesis

Question 19

Endpoint for WBI

Answer 19

clear rectal effluent or total irrigation volume >/10L

Question 20

Complications of WBI

Answer 20

1) vomiting/aspiration
2) Patient discomfort (bloating, flatulence, cramping)

(should NOT cause significant electrolyte abnormalities)

Question 21

3 methods of enhanced elimination

Answer 21

1) MDAC
2) Urinary alkalinization
3) Hemodialysis

Question 22

MOA MDAC

Answer 22

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’)

Question 23

Indications for MDAC

Answer 23

1) Drugs with enterohepatic or entero-entero circulation
2) SR products
3) Agents that form concretions or bezoars (e.g. carbamazepine, dapsone, quinine, phenobarb)

Question 24

Contraindications to MDAC

Answer 24

1) Unprotected airway
2) GI obstruction or ileus
3) GI tract not anatomically intact

Question 25

Compared to AC, what are patients that receive MDAC at greater risk of?

Answer 25

Bowel obstruction

Question 26

Examples of drugs where MDAC may be indicated

Answer 26

Carbamazepine, dapsone, phenobarb, quinines, theophylline

Question 27

Examples of drugs where urinary alkalinization may be indicated

Answer 27

1) Aspirin/salicylates
2) Methotrexate
3) Phenobarbital

Question 28

Examples of drugs where HD may be indicated

Answer 28

MMELS: metformin, methanol, ethylene glycol, lithium, salicylates (most common).

Question 29

Properties that make a toxin amenable to hemodialysis

Answer 29

LMW, low plasma protein binding, small volume of distribution, poor endogenous clearance.
Alt, may be indicated if severe acidosis is ppt’d by drug.

Question 30

Difference in fundamental mxn between single dose and multidose AC

Answer 30

Single dose is used to decrease poison absorption.

Multiple dose is used to increase poison elimination

Question 31

Why won’t urinary alkalinization work in hypokalemic patients?

Answer 31

Renal tubules will reabsorb K+ ions in exchange for hydrogen ions, prevent alkalinization

Question 32

MOA of urinary alkalinization

Answer 32

Increases renal elimination of a drug via ion trapping.

Question 33

How to alkalinize urine

Answer 33

Start with: 150 mEq NaHCO3 (3 amps) in 1L D5W, infuse at 1.5-2x maintenance IVF rate. Give K+ as indicated.

Question 34

Main risk with urinary alkalinization

Answer 34

Fluid overload due to high rate and large amount of Na+