title: Do small doses of atropine (<0.1 mg) cause bradycardia in young children?
abstract: OBJECTIVE
  To determine the heart rate response to atropine (<0.1 mg) in anaesthetised young infants.
  
  
  METHODS
  Prospective, observational and controlled.
  
  
  METHODS
  Elective surgery.
  
  
  METHODS
  Sixty unpremedicated healthy infants less than 15 kg were enrolled. Standard monitoring was applied. Anaesthesia was induced by mask with nitrous oxide (66%) and oxygen (33%) followed by sevoflurane (8%).
  
  
  METHODS
  Intravenous (IV) atropine (5 µg/kg) was flushed into a fast flowing IV. The ECG was recorded continuously from 30 s before the atropine until 5 min afterwards.
  
  
  METHODS
  The incidence of bradycardia and arrhythmias was determined from the ECGs by a blinded observer.
  
  
  RESULTS
  The median (IQR) age was 6.5 (4-12) months and the mean (95% CI) weight was 8.6 (8.1 to 9.1) kg. The mean (95% CI) dose of atropine was 40.9 (37.3 to 44) µg. Bradycardia did not occur. Two infants developed premature atrial contractions and one developed a premature ventricular contraction. When compared with baseline values, heart rate increased by 7% 30 s after atropine, 14% 1 min after atropine and 25% 5 min after atropine. Twenty-nine infants (48%) experienced tachycardia (>20% above baseline rate) after atropine lasting 222.7 s (range 27.9-286). The change in heart rate 5 min after atropine was inversely related to the baseline heart rate.
  
  
  CONCLUSIONS
  The upper 95% CI for the occurrence of bradycardia in the entire population of infants based on a zero incidence in this study is 5%. These results rebut the notion that atropine <0.1 mg IV causes bradycardia in young infants.
  
  
  BACKGROUND
  ClinicalTrials.gov #NCT01819064.
authors.affiliation: Department of Anesthesiology, Women and Children's Hospital of Buffalo, Buffalo, New York, USA.
authors.forename: Lara
authors.initials: L
authors.lastname: Eisa
authors.affiliation: Department of Anesthesiology, Women and Children's Hospital of Buffalo, Buffalo, New York, USA.
authors.forename: Yuvesh
authors.initials: Y
authors.lastname: Passi
authors.affiliation: Department of Anesthesiology, Women and Children's Hospital of Buffalo, Buffalo, New York, USA University of Rochester, Rochester, New York, USA.
authors.forename: Jerrold
authors.initials: J
authors.lastname: Lerman
authors.affiliation: Department of Anesthesiology, Women and Children's Hospital of Buffalo, Buffalo, New York, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Raczka
authors.affiliation: Department of Anesthesiology, Women and Children's Hospital of Buffalo, Buffalo, New York, USA University of Rochester, Rochester, New York, USA Division of Pediatrics, Women and Children's Hospital of Buffalo, Buffalo, New York, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Heard
mesh_terms: D000759:Adjuvants, Anesthesia / Q000008:administration & dosage / Q000009:adverse effects; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001285:Atropine / Q000008:administration & dosage* / Q000009:adverse effects; D001919:Bradycardia / Q000139:chemically induced*; D004334:Drug Administration Schedule; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007262:Infusions, Intravenous; D007430:Intraoperative Care / Q000009:adverse effects / Q000379:methods; D007431:Intraoperative Complications / Q000139:chemically induced*; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods; D011446:Prospective Studies
chemical_list: D000759:Adjuvants, Anesthesia; D000889:Anti-Arrhythmia Agents; D001285:Atropine
keywords: anticholinergic; arrhythmia; atropine; infants; vagal reflex