ATROPINE

Class

Parasympatholytic (anticholinergic)

Pharmacology and Actions

1. Increases heart rate (by blocking vagal influences).
2. Increases conduction through AV node.
3. Reduces motility and tone of GI tract.
4. Reduces action and tone of urinary bladder (may cause urinary retention).
5. Dilates pupils

Note: This drug blocks cholinergic (vagal) influences already present. If there is little cholinergic stimulation present, effects will be minimal.

Indications

1. To counteract excessive vagal influences responsible for some bradyarrhythmias.
2. To increase heart rate in hemodynamically significant bradycardia.
3. To improve conduction in AV heart block at the nodal level. Will not be effective when intranodal (Mobitz type II) block is suspected.
4. 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

1. 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.
2. People do well with chronic 2^d and 3`^d degree block. Symptoms occur mainly with acute change. Treat the patient, not the arrhythmia.
3. 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

1. Hemodynamically unstable bradycardia:
   1. 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).
   2. Pediatric: 0.02 mg/kg IV/IO, minimum 0.1 mg.
2. May be given through the ET tube at 2 times the IV dose. Maximum ET dose is 6 mg.
3. 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

1. Remember in cardiac arrest situations that atropine dilates the pupils.