From the Guidelines
Atropinization is indicated by clinical signs such as tachycardia, mydriasis, flushing of the skin, dry mucous membranes, decreased secretions, and mild confusion, and the goal is to achieve and maintain these signs during atropine infusion, as recommended by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. When administering atropine infusion, it is crucial to monitor for these signs of atropinization, which typically occur at doses of 0.5-1 mg IV, repeated every 3-5 minutes to a maximum dose of 3 mg, as outlined in the guideline 1. Some key points to consider when assessing atropinization include:
- Tachycardia, typically a heart rate above 80 beats per minute
- Mydriasis, or pupillary dilation
- Flushing of the skin
- Dry mucous membranes
- Decreased secretions
- Mild confusion It is essential to titrate the atropine infusion based on clinical response and to continue the infusion until secretions are controlled and the patient shows adequate atropinization without developing toxicity, as indicated by the guideline 1. Monitoring for signs of atropine toxicity, such as severe tachycardia, hyperthermia, urinary retention, ileus, and significant central nervous system effects, is also critical during atropine infusion, as these can indicate excessive dosing 1. The mechanism of atropine in blocking muscarinic acetylcholine receptors explains why these specific clinical signs indicate effective treatment, and the guideline provides a framework for managing patients with bradycardia and cardiac conduction delay, including the use of atropine infusion 1.
From the FDA Drug Label
Dryness of the mouth, blurred vision, photophobia and tachycardia commonly occur. Most adverse reactions are directly related to atropine's antimuscarinic action Dryness of the mouth, blurred vision, photophobia and tachycardia commonly occur with chronic administration of therapeutic doses.
The signs of atropinization for atropine infusion are:
From the Research
Signs of Atropinization
The signs of atropinization for atropine infusion can be identified through various studies. Some of the key points to consider are:
- Delirium, hallucinations, and the need for patient restraint are common signs of atropine toxicity, as seen in a study comparing titrated and ad hoc atropine dosing regimens 3.
- Atropine doses should be titrated against response and toxicity to minimize adverse effects 3.
- The use of a structured monitoring sheet may assist in more appropriate atropine use in anticholinesterase pesticide poisoning 3.
- In some cases, atropine administration can lead to paradoxical worsening of bradycardia, particularly in patients with heart block at the level of the His-Purkinje fibers 4.
- Atropine can increase heart rate and improve atrioventricular conduction by blocking parasympathetic influences on the heart, but low doses can result in paradoxical effects at the sinoatrial node and atrioventricular node 5.
Atropine Administration and Heart Rate
The administration of atropine can have varying effects on heart rate, including:
- Increasing heart rate in patients with bradycardia 5
- Causing initial tachycardia due to its rapid onset compared to neostigmine 6
- Having a paradoxical effect on heart rate in some patients, particularly those with heart block at the level of the His-Purkinje fibers 4
- Being used in combination with glycopyrrolate to minimize increases in heart rate after the reversal of muscle relaxant 7, 6
Key Considerations
When administering atropine, it is essential to consider the following:
- The dose and titration of atropine to minimize toxicity and adverse effects 3
- The potential for paradoxical effects on heart rate, particularly in patients with heart block 4, 5
- The use of structured monitoring sheets and education to ensure appropriate atropine use 3
- The combination of atropine with other medications, such as glycopyrrolate, to minimize adverse effects 7, 6