GENERAL APPROACH TO A POISONED VICTIM

Non-specific Treatment (Decontamination)

The next step in the management of a poisoned patient is to remove the unabsorbed poison from the skin, gut and other body parts and increase the excretion of absorbed poison from the body.

Decontamination of the skin - Wear gloves to avoid self-contamination!

Cleansing with soap + water: used after dermal exposure to
Organophosphates.
Mustard gas.
CS gas, a lacrimator or tear gas-compound
Explanation: soapy water has an alkaline pH at which these compounds are hydrolyzed.
Cleansing with acetic acid (vinegar): for nicotine (the acid protonates nicotine → ↓ dermal absorption).
B. Decontamination of the stomach
I. By evacuation of the stomach via emesis or gastric lavage
a. Emesis:
Ipecac syrup:
- Mechanism of action: Its alkaloids (emetine and cephalein) stimulate 5HT4-receptors on afferent vagus neurons in the stomach → vomiting reflex.
- Use: in the home or prehospital setting shortly following ingestion.
- Dose: 15 ml for children, 30 ml for adults; repeat it if ineffective within 30 min.
Contraindication of emesis induction:
unconsciousness (because the airways are not protected by the gag reflex?).
if the intoxication is caused by:
convulsive agents (TCAD, theophylline,) as emesis may precipitate convulsion.
acids, bases (risk of repeated exposure of the esophagus to these corrosive materials
gasoline (risk of aspiration).
b. Gastric lavage:
Can also be performed on unconscious patient because the airways are protected by endotracheal tube.
Procedure:
- Use a large bore tube. Before insertion, wet the tube with liquid paraffin (especially in atropine-intoxication?).
- The patient should lie on his/her left side with the head lowered.
- Insert 200-300 ml of saline, then drain it off.
- Repeat this until the gastric lavage fluid becomes water-clear (5-20 L may be needed).


II. By adsorbing the toxicant with adsorbents
activated charcoal
activated charcoal is an adsorbent with a very large specific surface area.
Use of charcoal:
*Single dose is 1-2 g/kg.
*Repeated administration for 2-3 days is required only if the toxic drug is slowly dissolved/released in the intestinal lumen, or undergoes EHC or intestinal excretion (e.g., carbamazepine, theophylline) to decrease their reabsorption and thus enhance fecal excretion.
AC Contraindicated in patients
who are sedated unless endotracheal intubation is performed first.
who have GI problems, e.g. absent bowel sounds (i.e. paralytic ileus), bowel obstruction, or perforation.
who require GI endoscopy (because charcoal will obstruct the view of mucosa from the endoscopist).
NOTE:
AC Ineffective against: iron, lithium, ethanol, methanol, acids, bases In such intoxications evacuate the stomach or perform WBI.
Other gastric adsorbents:
Deferoxamine: to bind ingested Fe-ions.
Fullers earth (a form of kaolin, Al-Mg-silicate): to bind ingested paraquat (herbicide).
Berlin blue (Prussian blue) complexes Tl+ (thallium) and radioactive isotopes of Cs+ (caesium, present in dirty bombs that may be used by terrorists).

III. Endoscopic or surgical removal of the solid toxicant

 Pieces of poisonous mushrooms may be removed by means of a gastroscope.
 Some drug formulations may form large coalescent gelatinous masses in the stomach, which may require endoscopic or even surgical removal.


C. Decontamination of the intestines by whole bowel irrigation (WBI)
Toxicological Indications of WBI
- Removal of slowly absorbed drugs: sustained-release or enteric coated prep.
- Removal of substances that are not bound by activated charcoal (e.g., lithium)
Non-toxicological Indications of WBI
- To remove swallowed packets containing illicit drugs in/from body packers.
- To evacuate the bowels for colonoscopy or barium X-ray examination.
Principle of WBI
The gut is flushed out with an isosmotic electrolyte solution containing polyethylene glycol (also called macrogol) which is not absorbed through the GI mucosa, thus it provides an appropriate osmotic pressure to prevent fluid movement.
Advantage of WBI
Decrease fluid movement across the mucosa.
NO volume depletion.
NO electrolyte imbalance may occur.

Procedure:

Examine the patient rectally to ascertain that stool passage is free.
The patient may drink the fluid, or the fluid may be pumped through a nasogastric tube into the stomach at a rate of 2 L/hr (for children 0.5 L/hr). Continue WBI until the rectal effluent is water-clear. It takes 2-6 hrs and 5-50 L of WBI fluid.
WBI may be combined with administration of charcoal and the prokinetic metoclopramide (i.m., or i.v.).
NOTE:
Decontamination of the intestine by osmotic cathartics (magnesium sulfate) is no longer recommended because it causes volume depletion and electrolyte imbalance.










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