Originally published at Pediatric EM Morsels on May 14, 2014. Reposted with permission.

Follow Dr. Sean M. Fox on twitter @PedEMMorsels

We have covered several other pediatric EM myths and misconceptions previously: Cuffed ETT are ok, a doughnut is not a good shape for LP Positioning, the 500:1 rule should not be used, Oral Rehydration is faster than IV, and you can/should give morphine to kids you are worried have appendicitis.

Recently, I was reminded of another myth that continues to have a foothold: Atropine and RSI.

WHAT I WAS TAUGHT: USE ATROPINE FOR RSI

• Kids will become bradycardic during RSI.
• Atropine is part of the LOAD pretreatment mnemonic for RSI.
  • Lidocaine, Opiate, Atropine, Defasiculating dose
  • Pediatric airway literature often recommends atropine for infants and children.
  • Thought to prevent the reflex bradycardia that comes with laryngoscopy and intubation.
• Listen to Smarter People than yourself
  • The American Heart Association, American College of Emergency Physicians and the American Academy of Pediatrics all support this view through the APLS and PALS textbooks.
  • While supporting the use, they also note that the use of atropine is NOT defined as “standard of care.”

Naturally, what I was taught can’t be wrong.  Well, maybe it’s not entirely correct though.

PHYSIOLOGY MATTERS:

• Neonates and infants have an imbalance of cardiac autonomic forces.
  • Predominant sympathetic tone within their SA and AV nodes.
    • Leads to higher resting heart rates.
  • Less sympathetic innervation to the bundle branches and ventricles.
    • Leads to less stability and exaggerated cardiac responses to stress.
• Can allow significant swings in the infant’s heart rate with stressors.
  • One of the biggest stressors children encounter during intubation is hypoxia.
    • Atropine can make the heart rate better, but cannot fix hypoxia.
  • Infants can also have bradycardia for less ominous reasons…
    • Yawning, defecation, and hiccups have all been associated with bradycardia.
    • Nasogastric tube placement can also lead to abrupt bradycardia.
    • No adverse events have been noted with these occurrences.
      • (So don’t give atropine to the kid with hiccups).
    • This imbalance diminishes by 9 months of age.

ATROPINE IS NOT INNOCUOUS:

• Don’t forget all medications have side-effects.
• Atropine is not without its problems.
  • Increases patient temperature and increases risk of malignant hyperthermia.
  • Increases ventricular arrhythmias – if given at too high of a dose.
  • Can actually cause bradycardia – if given at too small of a dose.
  • Increases risk of aspiration by relaxing the lower esophageal sphincter.
  • Lowers seizure threshold.
  • Can also mask other important causes of bradycardia.
    • Hypoxia
    • Increased intracranial pressure

KNOWN NOW: ATROPINE IS NOT REQUIRED

• The process of RSI can lead to bradycardia.
  • The act of laryngoscopy can lead to a bradycardic response.
    • However, this is transient and not likely to be hemodynamically significant.
  • Succinylcholine can cause bradycardia.
    • Literature, particularly OR-based research, does show that this occurs.
      • Most of the literature that supports the use of atropine involves repeated doses of succinylcholine, which is not typical for RSI.
      • This is another great reason to use Rocuronium instead.
• Hypoxia leads to bradycardia.
  • Peripheral chemoreceptors respond to hypoxia associated with apnea.
    • The apnea-associated bradycardia can deteriorate and lead to hemodynamic instability.
    • Atropine can ameliorate the HR number, but will neither fix the hypoxia nor the apnea.
  • Literature suggests that physiologic factors, like hypoxia, play a more important role in causing bradycardia than the stimulation from laryngoscopy.
  • Bradycardia associated with laryngoscopy is an uncommon event.
    • In a study’s population that had low use of succinylcholine, there was only 4% incidence of bradycardia.
  • Bradycardia still can occur in patients who are pretreated with atropine.
    • This is especially true if hypoxia occurs.

MY HUMBLE TAKE ON ATROPINE AND RSI

The decision to intubate any patient is one of the most important that we make as physicians.  It is very complex and hazardous, without question.  With this in mind, we need to focus on the things that will optimize first attempt success:

1. Good positioning and Equipment (ex, suction) set up
2. Excellent pre-oxygenation
3. Selection of appropriate sedative and paralytic
4. Use of continuous apneic oxygenation
5. Excellent technique (possibly with videoscopic tools)
6. Confirmation of successful placement

This is a complicated process, which is not made easier by adding additional medications, especially, when that added medication may lead to a dose calculation error, adverse side effect, or mask of more important causes of bradycardia.  For these reasons, atropine is not be routinely needed as a part of RSI.

It should be handy, especially if intubating an infant (<9-12 months) or if you need to re-dose succinylcholine.

More importantly, if you encounter bradycardia, don’t think “atropine deficiency,” think “oxygen deficiency.”

References