ATROPINE
From CRS EMS Guidelines
Class
Parasympatholytic (anticholinergic)
Pharmacology and Actions
- Increases heart rate (by blocking vagal influences).
- Increases conduction through AV node.
- Reduces motility and tone of GI tract.
- Reduces action and tone of urinary bladder (may cause urinary retention).
- Dilates pupils
Note: This drug blocks cholinergic (vagal) influences already present. If there is little cholinergic stimulation present, effects will be minimal.
Indications
- To counteract excessive vagal influences responsible for some bradyarrhythmias.
- To increase heart rate in hemodynamically significant bradycardia.
- To improve conduction in AV heart block at the nodal level. Will not be effective when intranodal (Mobitz type II) block is suspected.
- As an antidote for some insecticide exposures (organophosphate poisoning) and nerve gases with symptoms of excess cholinergic stimulation: salivation, constricted pupils, bradycardia, tearing, diaphoresis, vomiting, and diarrhea.
Precautions
- Bradycardias in the setting of an acute MI are common and may be beneficial. Do not treat them unless there are signs of poor perfusion (low B/P, mental confusion). If in doubt, consult with the base physician.
- People do well with chronic 2d and 3`d degree block. Symptoms occur mainly with acute change. Treat the patient, not the arrhythmia.
- Pediatric bradycardias are most commonly secondary to hypoxia. Correct the ventilation first, and only treat the rate directly if that fails. Epinephrine is almost always the first-line medication for bradycardia in pediatric patients.
Administration
- Hemodynamically unstable bradycardia:
- Adult: 1 mg IV/IO, repeated if needed at 3-5 minute intervals to a dose of 3mg. (Stop at ventricular rate which provides adequate medication and B/P).
- Pediatric: 0.02 mg/kg IV/IO, minimum 0.1 mg.
- May be given through the ET tube at 2 times the IV dose. Maximum ET dose is 6 mg.
- For symptomatic insecticide/organophosphate poisoning exposures: Usually begin with 2 mg IV/IO and titrate (2 mg q 5 min) until secretions are dried. Total required dose may be massive.
Side Effects and Special Notes
- Remember in cardiac arrest situations that atropine dilates the pupils.