TLM. FOWZANFACULTY OF MEDICINERAJARATA UNIVERSITY

SRI LANKA

Organophosphate Poisoning

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.

Actioninhibit acetylcholine esterase enzymeat nerve endings by phosphorylation acetylcholine at receptor sites

clinical features depends on route of entry

ingestion inhalation eye contact

Ingestion

Muscarinic effects(post ganglionic parasympathetic nerve ending)• Bronchospasm(wheezing)• Bronchorrhoea• Productive cough• Dyspnoea• Hypotension• Bradycardia• Cardiac arrhythmia• Diarrhoea • Vomiting• Salaivation• Tenesmus• Miosis• Lacrimation• Blurred vision

Nicotinic effects (neuro muscular junction)• Muscle weakness• Fasciculation• Paralysis• Muscle twitching

Nicotinic and muscarinic Ach receptors in the CNS

• Confusion• Agitation• Respiratory failure• Ataxia• convulsion

Ach receptors in the sympathetic system

• Excessive sweatingOther effects• hyperglycaemia• Acute pancreatitis

Inhalation

• Cough• Difficulty in breathing• Bronchitis• Pneumonia

Eye contact

• Irritation• Pain• Lacrimation• Miosis• Blurring vision• Photophobia

All the clinical features in from

head to Toe

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.

GASTRIC LAVAGE ACTIVATED CHARCOAL

OROPHARYNGEAL AIRWAY USED AMBU VENTILATION & ET TUBE

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

Maintenance infusiononce 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 - tachycardiaPralidoximegive 30mg/kg loading dose Iv over 10-20mins followed by continuous infusion of 8-10mg/kg/hr until clinical recovery.

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 flaringcranial nerve palsies

5. ventricular tachycardia- temporary pacing 6.bronchopneumonia- antibiotics & chest physiotherapy

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