2. Organophosphate(insecticide)
organophosphate poisoning accounts for nearly one third of
hospital admissions from poisoning in Sri Lanka.
Commonly using trades are follows.
Malathion, parathion, diazinon, fenthione, chlorpyrifos.
Action
inhibit acetylcholine esterase enzyme
at nerve endings by phosphorylation
acetylcholine at receptor sites
clinical features
depends on route of entry
ingestion inhalation eye contact
4. Nicotinic and muscarinic Ach receptors in the
Ach receptors in the CNS sympathetic system
• Confusion • Excessive sweating
• Agitation Other effects
• Respiratory failure
• Ataxia • hyperglycaemia
• convulsion • Acute pancreatitis
7. Management of organophosphate poisoning
1. check airway, breathing, circulation.
2. monitor arterial oxygen saturation, cardiac rhythms, BP,
Pulse rate.
3. look for signs & symptoms.
4. obtain IV access.
5. remove the contaminated clothes&wash the skin
thoroughly with soap & water
6. give atropine intravenously as soon as possible for
symptomatic patient
7. perform gastric decontamination with gastric lavage once
the patient is stabilised & within two hours of ingestion.
8. give activated charcoal (50 g in 200 ml)
9. maintainance atropine infusion
10. give pralidoxime.
9. Atropinisation
-start with 1.8-3.0 mg fast iv bolus
-after 3-5minutes check the five parameters of cholinergic
poisoning
1. Poor air entry into the lungs due to bronchorroea &
bronchospasm
2.excessive sweating
3. bradycardia ( <60 )
4. hypotension
5. miosis
-If above parameters are not corrected
double the dose of atropine every 5 minutes until atleast 3/5 of
below parameters corrected
-clear chest with no wheeze
-dry axillae
-heart rate 80-100 bpm
-systolic BP > 90 mmhg
-pupils no longer pinpoint
10. Maintenance infusion
once the patient is stable start an infusion of 5% dextrose containing 10-20% of the
total initial dose of atropine on an hourly basis
stop atropine infusion if features of toxicity appears
-confusion
-urinary retention
-hyperthermia
- bowel ileus
- agitation
- flushing
- tachycardia
Pralidoxime
give 30mg/kg loading dose Iv over 10-20mins followed by
continuous infusion of 8-10mg/kg/hr until clinical recovery.
11.
12. Management of complications
1.Respiratory failure- ET intubation and mechanical
ventilation required if
- tidal volume <5mm/kg
- vital capacity < 15 ml/kg
-apnoic spells are present
-PaO2 < 08 Kpa& FiO2 > 60%
-severe pulmonary oedema
2.Pulmonary oedema- give furosemide 40-80 mg iv
3.convulsion – give 5-10 mg iv diazepam
4.intermediate syndrome
weakness of neck flexion tachypnoea
use of accessory muscle of respiration sweating
proximal muscle weakness nasal flaring
cranial nerve palsies
5. ventricular tachycardia- temporary pacing
6.bronchopneumonia- antibiotics & chest physiotherapy