GuidelinesOther guideline
Infusion: Atropine - Organophosphate Poisoning
Organophosphate poisoning – avoid aminoglycosides, suxamethonium, phenothiazines and theophylline. Control convulsions with a benzodiazepine.
| Trade names: | Presentation and strength: |
| Atropine sulphate. | 0.5mg/ml and 1mg/ml ampoules. |
| Cautions: see SAMF. | |
| Organophosphate poisoning – avoid aminoglycosides, suxamethonium, phenothiazines and theophylline. Control convulsions with a benzodiazepine. | |
| Loading dose: | |
| Adult: SAMF: Initial test dose of 1mg in adults. Followed by 0.05mg/kg every 15 minutes until full atropinization is achieved. GSH:1-2mg IV initial dose. Repeat and double dose every 5 minutes until atropinised. Give initial dose IM while acquiring IV access if necessary. | Paediatric: SAMF: Initial test dose of 0.01mg/kg IV bolus. Followed by 0.05mg/kg every 15 minutes until full atropinization is achieved. GSH: (Unclear history or minimal symptoms: 0.01 mg/kg and then proceed with a doubling dose every 5 minutes titrated against response; if the child is clearly symptomatic or confirmed history start with 0.03 mg/kg and titrate using a doubling dose) |
| Commonly for 70kg adult: 1mg IV bolus test dose. Followed by 2 to 4mg every 15 minutes. Dose varies widely according to level of poisoning – if atropinised with only one or two doses then the poisoning is likely very mild. Can require very large doses. | Neonatal: N/A. |
| Constant infusion: | |
| Adult dosage range: 0.02 to 0.08mg/kg/hr constant infusion once full atropinization has been achieved. Higher doses may be required – can require 10-20mg/hr in severe poisonings. | Paediatric dosage range: Range from 0.01 to 0.03 mg/kg (or as for adult) [Commence at 10% of total loading dose per hour and titrate to keep patient atropinised.] |
| Neonatal dosage range: N/A. | |
| Regime for 70kg adult: | Regime for paediatrics: |
| Mixture: 10mg/50ml = 40mg/200ml = 0.2mg/ml. | Mixture: 1mg/50ml = 4mg/200ml = 20mcg/ml. |
| Rate: Start at 0.02mg/kg/hr = 1.4 to 5.6mg/hr. 7 to 28ml/hr. | Rate: 1 to 4ml/kg/hr. |
| Alternative adult regime: | Alternative paediatric regime: |
| Mixture: 40mg/200ml = 0.2mg/ml. | Mixture: 1mg/50ml = 4mg/200ml = 20mcg/ml. |
| Rate: Commence at 10% of total loading dose per hour and titrate to keep patient atropinised. 10 to 20mg/hr = 50 to 100ml/hr. | Rate: 0.5ml/kg/hr to 1.5ml/kg/hr titrated upwards to effect. |
| Additional notes: | |
| The primary end point of atropinisation is drying of bronchial secretions (manifest as crepitations and wheeze). Pupil size can only be used as an end point if miosis is present on admission. Also: the dilation of pupils often lags behind other signs of atropinsiation. Generally, aim to keep heart rate above 100 bpm. Dosage requirements are extremely variable may need to be doubled or quadrupled – double or quadruple the concentration rather than the rate. If fluid volumes are too great, double or quadruple the concentration, and administer half to one quarter of the rate. | |
| Other: | |
| See Eddleston et al for further guidance and for an example of an atropine monitoring sheet. Good notes at http://curriculum.toxicology.wikispaces.net/ Acknowledgements to Dr Ross Hofmeyr for contributing to this protocol. | |