title: The Effect of Caffeine on Diaphragmatic Activity and Tidal Volume in Preterm Infants.
abstract: OBJECTIVE
  To determine the effect of caffeine on diaphragmatic activity, tidal volume (Vt), and end-expiratory lung volume (EELV) in preterm infants.
  
  
  METHODS
  Using transcutaneous electromyography of the diaphragm (dEMG), we measured diaphragmatic activity from 30 minutes before (baseline) to 3 hours after administration of an intravenous caffeine-base loading dose in 30 spontaneously breathing preterm infants (mean gestational age, 29.1 ± 1.3 weeks), most of whom were on noninvasive respiratory support. Diaphragmatic activity was expressed as the percentage change in dEMG amplitude, area under the curve, respiratory rate, and inspiratory and expiratory times. Using respiratory inductive plethysmography, we measured changes in Vt and EELV from baseline. These outcome variables were calculated at 8 fixed time points after caffeine administration (5, 15, 30, 60, 90, 120, 150, and 180 minutes) and compared with baseline.
  
  
  RESULTS
  Caffeine administration resulted in rapid (within 5 minutes) increases in dEMG amplitude (median, 43%; IQR, 24%-63%; P < .001) and area under the curve (median, 28%; IQR, 14%-48%; P < .001). Vt also increased by a median of 30% (IQR, 7%-48%), and this change was significantly correlated with the change in dEMG amplitude (r = 0.67; P < .001). These effects were relatively stable until 120 minutes after caffeine administration. Caffeine did not consistently impact EELV, respiratory rate, or inspiratory and expiratory times.
  
  
  CONCLUSIONS
  Caffeine treatment results in a rapid and sustained increase in diaphragmatic activity and Vt in preterm infants.
authors.affiliation: Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: j.v.kraaijenga@amc.nl.
authors.forename: Juliette V
authors.initials: JV
authors.lastname: Kraaijenga
authors.affiliation: Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Hutten
authors.affiliation: Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Frans H
authors.initials: FH
authors.lastname: de Jongh
authors.affiliation: Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Anton H
authors.initials: AH
authors.lastname: van Kaam
mesh_terms: D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003964:Diaphragm / Q000187:drug effects*; D004576:Electromyography; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D010991:Plethysmography; D011446:Prospective Studies; D013990:Tidal Volume / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine