title: The effect of epinephrine by nebulization on measures of airway obstruction in patients with acute severe croup.
abstract: OBJECTIVE
  To demonstrate that tests of pulmonary function applicable to sick infants and small children with acute severe viral croup would provide clear, objective evidence of responsiveness to therapy with nebulized epinephrine.
  
  
  METHODS
  Oesophageal pressure changes and airflows at the mouth were measured in 17 patients with acute severe croup, before and after nebulization with epinephrine.
  
  
  RESULTS
  In 12 of the 17 patients there was a significant improvement in respiratory mechanics following epinephrine nebulization. Six of the 12 patients who responded to adrenaline also received 0.9% saline by nebulization, without improvement. No measures derived from combined flow and volume data showed any statistically significant change following epinephrine nebulization. Measures combining flow and pressure data, specifically inspiratory airway resistance, expiratory airway resistance, work of breathing, rate of work of breathing and volume for effort, showed changes of 26%, 33%, 16%, 16% and 46% respectively. The most statistically significant measures were pressure-rate product, pressure-time integral, oesophageal pressure alone and expiratory resistance. These changes persisted for at least 10 min after inhalation although there was some evidence of decline in pharmacologic effect at that time.
  
  
  CONCLUSIONS
  Nebulized epinephrine results in a short-lived improvement in some but not all patients with croup. This reduction in respiratory effort occurs secondary to a decline in inspiratory and expiratory airway resistance. Oesophageal pressures measured via a feeding tube are satisfactory for quantification of the acute response and may be a useful continuous monitoring device. Flow measurements are unhelpful, and continuous administration of nebulized epinephrine should be investigated.
authors.affiliation: Division of Paediatric Critical Care and Children's Heart Disease, Red Cross War Memorial Children's Hospital and University of Cape Town, Rondebosch, 7700 Cape Town, South Africa. andrew.argent@uct.ac.za
authors.forename: A C
authors.initials: AC
authors.lastname: Argent
authors.forename: M
authors.initials: M
authors.lastname: Hatherill
authors.forename: C J L
authors.initials: CJ
authors.lastname: Newth
authors.forename: M
authors.initials: M
authors.lastname: Klein
mesh_terms: D000402:Airway Obstruction / Q000175:diagnosis*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003440:Croup / Q000188:drug therapy*; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007223:Infant; D009330:Nebulizers and Vaporizers; D010223:Parainfluenza Virus 2, Human; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D013019:South Africa; D016896:Treatment Outcome
chemical_list: D001993:Bronchodilator Agents; D004837:Epinephrine