157. Pesticides

Question 1

Mechanism of organophosates

Answer 1

Inhibition of cholinesterases results in accumulation of acetylcholine at multiple receptors within the body

Question 2

Toxidrome of cholinergic

Answer 2

SLUDGE and the killer Bs
S = Salivation

L = Lacrimation

U = Urinary incontinence

D = Diarrhea

G = Gastrointestinal cramps

E = Emesis

(Killer) Bs: Bradycardia/bronchorrhea/bronchospasm

Question 3

Other effects of cholinergics (3)

Answer 3

At the neuromuscular junction, excess acetylcholine causes hyperstimulation of the muscles with secondary paralysis, and when the diaphragm is affected, cholinesterase poisoning leads to respiratory arrest.
Seizures
Pulmonary edema

Question 4

4 main goals in MGMT of organophosphate

Answer 4

decon
resp stabilization
- supportive
reverse ACH
reverse toxin binding

Question 5

How to stop ACH at receptors

Answer 5

Atropine
• 1-3mg and double every 5 minutes to effect
• May have HUGE doses
• Infusion at 10-20% initial used dose per hour

Question 6

How to regenerate cholinesterase

Answer 6

• Pralidoxime

* Indicated for resp depression, seizure, dysrhythmia

Question 7

Indications for oximes

Answer 7

respiratory depression or failure,
muscle fasciculations,
seizures,
dysrhythmias,
hemodynamic instability,
or the use of large amounts or repeated doses of atropine to completely control signs and symptoms of organophosphate intoxication.

Question 8

4 acute complications from organophosphate

Answer 8

Complications from SLUDGE
Complications from the killer B’s
Respiratory failure
Seizures, coma, death

Question 9

What is the difference between organophosphates and carbamates?

Answer 9

(1) short duration of effect (minutes to

24 to 48 hours)

(2) the process of aging does not occur
(3) No need for Oxime therapy

Question 10

What is an example of a chlorinated hydrocarbon?

Answer 10

Dichlorodiphenyltrichloroethane (DDT) is the best-known example of chlorinated hydrocarbon insecticides. This class is also known as organochlorine insecticides.

Question 11

What are the unique features of chlorinated hydrocarbon toxicity

Answer 11

MOST IMPORTANT ASPECT = refractory seizures from complete GABA blockage. If Benzos are ineffective switch to barbituates,

Question 12

MGMT of chlorinated hydrocarbon

Answer 12

Decontamination
Remove all clothing and wash the skin and hair with soap and water.
Stabilization / supportive care
- Treat seizures
- Benzo’s and Barbs
- Treat the catecholamine surge induced tachydysrhythmias with metoprolol
- Treat hyperthermia, metabolic acidosis, rhabdomyolysis, AKI
No role for enhanced elimination
No antidote known

Question 13

How do Substituted Phenols (Dinitrophenol) cause toxicity?

Answer 13

Substituted phenols uncouple oxidative phosphorylation. This results in decreased adenosine triphosphate (ATP) formation and increased heat generation, which is the mechanism of action for DNP in weight loss because calories are burned excessively. DNP also stimulates glycolysis, which, along with the uncoupling of oxidative phosphorylation, increases lactic acid production.

Question 14

What is Substituted Phenols (Dinitrophenol)

Answer 14

Weight loss meds

Question 15

What is MGMT of agent orange

Answer 15

Decontamination
dermal exposure=remove the clothing and wash the skin with soapy water
activated charcoal is not indicated
Stabilization and Supportive Care
fluid resuscitation is the mainstay
Enhanced Elimination
critically ill patient = urinary alkalinization or hemodialysis can be used
Antidote = none

Question 16

What is mechanism of paraquat toxicity

Answer 16

Paraquat causes production of superoxides created during cyclic oxidation-reduction reactions in tissues

Question 17

Main area of damage in paraquat

Answer 17

Paraquat selectively concentrates in the lungs, regardless of the route of exposure

Question 18

MGMT of paraquat

Answer 18

Decontamination

• Dermal = treated by removing soiled clothing and washing the skin with water
• In general, no gastrointestinal decontamination
• Paraquat consider GI decon because of potential lethality
• Use AT LEAST 100 g activated charcoal within 1 hour of ingestion

Stabilization and Supportive Care

• Upper airway corrosive injury can lead to an obstructed airway = ETT early
• Target SPO2 >95% as hyperoxia WORSENS LUNG DAMAGE

Enhanced Elimination
- Hemodialysis = controversial. If renal failure, metabolic acidosis, or electrolyte imbalance develops as a result of the poisoning, dialysis is indicated

Antidote Therapy
- Currently no specific antidotal therapy

Question 19

What is the aging process in organophosphate insecticide ingestions?

Answer 19

irreversible conformational change that occurs when the organophosphate is bound to the cholinesterase enzyme for a prolonged time. This causes the clinical effects to persist for periods of days to weeks.

Question 20

What is the maximum formulation of DEET in pediatrics? When should you not use DEET?

Answer 20

30% as the maximum concentration for use in infants and children and does not recommend use of DEET in infants younger than 2 months old