title: Estimating 'lost heart beats' rather than reductions in heart rate during the intubation of critically-ill children.
abstract: OBJECTIVE
  Reductions in heart rate occur frequently in children during critical care intubation and are currently considered the gold standard for haemodynamic instability. Our objective was to estimate loss of heart beats during intubation and compare this to reduction in heart rate alone whilst testing the impact of atropine pre-medication.
  
  
  METHODS
  Data were extracted from a prospective 2-year cohort study of intubation ECGs from critically ill children in PICU/Paediatric Transport. A three step algorithm was established to exclude variation in pre-intubation heart rate (using a 95%CI limit derived from pre-intubation heart rate variation of the children included), measure the heart rate over time and finally the estimate the numbers of lost beats.
  
  
  RESULTS
  333 intubations in children were eligible for inclusion of which 245 were available for analysis (74%). Intubations where the fall in heart rate was less than 50 bpm were accompanied almost exclusively by less than 25 lost beats (n = 175, median 0 [0-1]). When there was a reduction of >50 bpm there was a poor correlation with numbers of lost beats (n = 70, median 42 [15-83]). During intubation the median number of lost beats was 8 [1]-[32] when atropine was not used compared to 0 [0-0] when atropine was used (p<0.001).
  
  
  CONCLUSIONS
  A reduction in heart rate during intubation of <50 bpm reliably predicted a minimal loss of beats. When the reduction in heart rate was >50 bpm the heart rate was poorly predictive of lost beats. A study looking at the relationship between lost beats and cardiac output needs to be performed. Atropine reduces both fall in heart rate and loss of beats. Similar area-under-the-curve methodology may be useful for estimating risk when biological parameters deviate outside normal range.
authors: Critical Care Group - Portex Unit, Institute of Child Health, University College London, London, United Kingdom ; Paediatric Intensive Care - Réanimation Pédiatrique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France.
authors: Peter
authors: P
authors: Jones
authors: Department of Mathematics, University College London, London, United Kingdom.
authors: Nick
authors: N
authors: Ovenden
authors: Paediatric Intensive Care - Réanimation Pédiatrique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France ; Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors: Stéphane
authors: S
authors: Dauger
authors: Critical Care Group - Portex Unit, Institute of Child Health, University College London, London, United Kingdom.
authors: Mark J
authors: MJ
authors: Peters
mesh_terms: D001285:Atropine / Q000494:pharmacology; D002648:Child; D016638:Critical Illness; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007440:Intubation; D008297:Male
chemical_list: D001285:Atropine