Poisioning

Question 1

Children younger than age ______ years are primarily involved in
accidental exposures, with the peak incidence in _________ year-olds

Answer 1

Children younger than age 6 years are primarily involved in
accidental exposures, with the peak incidence in 2-year-olds

Question 2

Standard pharmacokinetics (absorption, distribution, metabolism, and elimination) often _________ be applied in the setting of a supra-therapeutic exposure!

Answer 2

CAN NOT

Question 3

What is LD50?

Answer 3

• lethal dose
  the amount per kilogram of body weight of a drug required to kill 50% of a group of experimental animals or median lethal dose
• little clinical value in humans.

Question 4

What are some factors that can delay absorption? (3)

Answer 4

large overdose
hypotension
decreased gut-mobility

Question 5

In an acute salicylate overdose (150 mg/kg), the apparent t1/2 is prolonged to ______ hours.

Answer 5

24-30h

Question 6

How is volume of distribution determined?

Answer 6

The volume of distribution (Vd) of a drug is determined by dividing the
amount of drug absorbed by the blood level.

Question 7

When should poison prevention begin?

Answer 7

At the 6-month well-baby visit

Question 8

General treatment of poisoning

Answer 8

• telephone contact (can reduce morbidity and mortality)
• basic info
• agent and amount ingested
• patient’s present condition
• time elapsed since ingestion
• evaluation whether emergency transport is needed
• determine where and who consumed the substance (school, home, one child, more children etc.)

Question 9

Initial emergency department contact

Answer 9

• ABC
• treat shock (lay the patient flat, IV solution, vasopressors if needed)
• treat burns (sterile solution/water, decontamination, irrigation with pH assessment)
• take pertinent history (determine poisons in home or purity of water supply)

Question 10

Definitive therapy of poisoning - Prevention of absorption (4)

Answer 10

A. Emesis and lavage
- rarely used in paediatric patients, except in TCA overdose

B. Charcoal
- never give it to patients with altered sensorium due to risk of aspiration
- 1-2 g/kg per dose, max 100g
- not useful in heavy metal, may be harmful in hydrocarbons, caustics and solvent ingestion

C. Catharsis
- do not improve outcome, should be avoided

D. Whole gut lavage
- uses an orally administered, non-absorbable hypertonic solution
- the use of this procedure in poisoned patients remains controversial
- some recommendations are mechanical movement of items in bowel (cocaine packets for ex) and poisoning with substances poorly absorbed by charcoal (lithium)

Question 11

Definitive therapy of poisoning - Enhancement of Excretion (4)

Answer 11

Excretion of certain substances can be hastened by urinary alkalisation or dialysis and is reserved for very special circumstances

• saline bolus 10-20 mL/kg with sufficient IV to maintain urine output at 2-3 ml/kg/h

A. Urine alkalisation
- pKa is less than 7.5, urinary alkalisation is appropriate; if it is over 8.0, this technique is not usually beneficial
- sodium bicarbonate (be careful of hypokalaemia)

B. Dialysis
- may be necessary in renal failure or pulmonary edema
- mostly used for salicylate and methotrexate