Organophosphate Poisoning Syndrome

Question 1

Why is organophosphate poisoning syndrome common in farmers

Answer 1

OPs used as pesticides
Often sprayed with no PPE

Question 2

Organophosphate poisoning MOA

Answer 2

Inhibits acetylcholinesterase

Question 3

OP poisoning Mx

Answer 3

O2 (unless Paraquat poisoning)
Atropine
Pralidoxime
Sodium bicarbonate - prevent acidosis
Magnesium sulphate - prevent dysrhythmia

Question 4

OP poisoning presentation

Answer 4

Nicotinic activation signs
Muscarinic activation signs
Desquamation
Liver failure
Renal failure
Lung fibrosis

Question 5

Nicotinic activation signs

Answer 5

Weakness
Fasciculations
Cramps
Paralysis
Tachycardia
HTN

Question 6

Muscarinic activation signs

Answer 6

SLUDGE - salivation lacrimation urination diarrhoea GI cramps emesis
Anxiety, restlessness
Ataxia
Convulsions
Circ collapse
Bradycardia
Hypotension
Blurry vision
Miosis
Rhinorrhea

Question 7

How should atropine be given in OP poisoning

Answer 7

Loading bolus 0.6-3mg, then doubling dose every 5 mins until pt atropinised
Infuse 10-20% of total dose required to atropinise each hr in normal saline

Question 8

At what point is an OP poisoning pt considered atropinised

Answer 8

HR >80
SBP >80
Clear lungs

Question 9

Pralidoxime MOA

Answer 9

reactivate cholinesterase which has been inactivated by phosphorylation due to an organophosphate pesticide or related compound

Question 10

Pralidoxime administration

Answer 10

Loading 20-30mg/kg over 30 mins
Repeat 6-8hrs cont infusion
48hrs tx min

Question 11

How does NaCO3 help OP poisoning

Answer 11

Prevents acidosis
Incr OP clearance through pH mediated hydrolysis

Question 12

How does MgSO4 help OP poisoning

Answer 12

Blocks Ca+ channels decreasing synaptic ACH release
Decr VT risk
Decr cholinergic stim

Question 13

Proposed future OP poisoning tx

Answer 13

Lipid emulsion
Some OPs are highly lipid soluble