General Treatment of Poisoning

The first principle in the management of a poisoned patient is to treat the patient, not the poison. Airway, breathing and circulation are addressed initially, along with any other immediately life-threatening toxic effect.

Occupational Toxicology
This deals with chemicals found in the workplace. The major emphasis of occupational toxicology is to identify the agents of concern, identify the acute and chronic diseases that they cause, define the conditions under which they may be used safely, and prevent the absorption of harmful amounts of these chemicals.

In a poisoned patient:
  • Hypotension occurs due to depression of cardiac contractility
  • Hypovolemia results due to vomiting and diarrhea
  • Peripheral vascular collapse due to blockade of alpha-adrenoceptor mediated vascular tone.
  • Hypothermia or hyperthermia due to temperature dysregulation
  • Cellular hypoxia may occur especially in case of cyanide poisoning
  • Seizures, muscular hyperactivity, and rigidity may result in death

Initial Management of the Poisoned Patient
Supportive measures are the basic ABCD of poisoning treatment:

A is for the Airways. It should be cleared. There should be no obstruction. Endo tracheal tube is inserted if needed. For many patients simple poisoning in the lateral left side down position is sufficient to clear the airways.

B is for breathing. It should be assessed by observation and pulse. patients with respiratory insufficiency should be incubated and mechanically ventilated.

C is for circulation. It should be assessed by observation continuous monitoring of pulse rate, blood pressure, urinary output, and evaluation of peripheral perfusion.

D every patient with altered mental status should receive a challenge with concentrated DEXTROSE unless a rapid bedside glucose test demonstrates that the patient is not hypoglycemic. Adults are given 25g (50ml of 50% dextrose solution) IV and children 0.5 g/kg ( of 25% dextrose).

Helping Someone who is Conscious
If the person has swallowed something, try to get them to spit out anything that is remaining in their mouth.
Try to wake the patient and encourage them to spit out anything left in their mouth. Lie the person on their with the help of a cushion behind their back and their upper leg pulled slightly forward so that they don’t fall on their face or roll backward. 
This is known as the recovery position. If the person isn’t breathing or their heart is stopped, begin CPR- cardiopulmonary resuscitation.

Hospital Treatment
Some people who have swallowed a poisonous substance or overdosed on medication will be admitted to the hospital for examination and treatment.

Possible treatments that can be used to treat poisoning include:
  1. Activated charcoal – sometimes used to treat someone who's been poisoned; the charcoal binds to the poison and stops it being further absorbed into the blood
  2. Antidotes – these are substances that either prevent the poison from working or reverse its effects
  3. Sedatives – may be given if the person is agitated
  4. A ventilator (breathing machine) – may be used if the person stops breathing
  5. Anti-epileptic medicine – may be used if the person has seizures (fits)

Common Toxic Syndromes

1. Acetaminophens
Commonly involved in suicide attempts and accidental poisoning. Acute ingestion of more than 150-200 mg/kg or 7g total (adults) is considered potentially toxic.
Initially, the patient is asymptomatic or mild GIT upset. After 24-36hrs liver injury appears. Levels of aminotransferases and hypoprothrombinemia are elevated. The antidote is acetylcysteine acts as a glutathione substitute, binding to toxic metabolites as it is produced.

2. Amphetamines and other stimulants
These drugs are commonly abused. These are also used as metabolic enhancers or fat burners. There over doze include agitation, confusion and seizures, diarrhea, urination, miosis, and weakness. 
Blood testing may be used to document the depressed activity of red cells and plasma enzymes. There is no specific antidote. Seizures are managed with benzodiazepines. Temperature is reduced by removing clothes.

3. Isopropanol (rubbing alcohol, isopropyl alcohol)
It is metabolized to acetone via alcohol dehydrogenase. Acetone can not be further oxidized to carboxylic acids and therefore, acidemia does not occur. IPA is a known CNS depressant and GIT irritant.

Elimination Enhancement

The elimination of some toxins may be enhanced by hemodialysis if certain properties are met: low protein binding, small volume distribution, small mol.wt and water solubility of toxins. Drugs like methanol, salicylates, theophylline and lithium can be removed by hemodialysis.

2-Urinary alkalization
Alkalization of urine enhances the elimination of salicylates or phenobarbital. Increasing the Ph with IV sodium bicarbonate transforms the drug into an ionized form that prevents reabsorption. The goal urine ph is within the range 7.5-8 while ensuring that the serum ph does not exceed 7.55.

3-Multiple-dose activated charcoal
This therapy enhances the elimination of certain drugs eg theophylline, phenobarbital, digoxin etc. by creating gradient across lumen of the gut. Medication transverse from areas of high concentration to low concentration, promoting medication already absorbed to cross back into the gut to be absorbed by the activated charcoal present.

4-Gastric emptying
It does not clearly reduce overall morbidity or mortality and has risks. Gastric emptying is considered if it can be done within 1 h of life-threatening ingestion. However, many poisonings manifest too late, and whether a poisoning is life-threatening is not always clear. Thus, gastric emptying is seldom indicated.

5-Whole-bowel irrigation
This procedure flushes the GI tract and theoretically decreases GI transit time for pills and tablets. Irrigation has not been proven to reduce morbidity or mortality. Irrigation is indicated for any of the following:
  • Some serious poisonings due to sustained-release preparations or substances that are not adsorbed by charcoal (eg, heavy metals)
  • Drug packets (eg, latex-coated packets of heroin or cocaine ingested by body packers)
  • A suspected bezoar

A commercially prepared solution of polyethylene glycol (which is nonabsorbable) and electrolytes is given at a rate of 1 to 2 L/h for adults or at 25 to 40 mL/kg/h for children until the rectal effluent is clear; this process may require many hours or even days. The solution is usually given via a gastric tube, although some motivated patients can drink these large volumes.

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