title: Monitoring tidal volumes in preterm infants at birth: mask versus endotracheal ventilation.
abstract: OBJECTIVE
  Upper airway distention during mask ventilation could reduce gas volumes entering the lung compared with ventilation via an endotracheal tube. Therefore, respiratory tract volumes were measured in lambs and tidal volumes were compared in preterm infants before and after intubation.
  
  
  METHODS
  In seven preterm lambs, volumes of the airways (oropharynx, trachea, lungs) were assessed. In 10 preterm infants, delta pressures, tidal volumes and leak were measured during ventilation 2 min before (mask ventilation) and 2 min after intubation (endotracheal ventilation). Inflations coinciding with breaths were excluded.
  
  
  METHODS
  Amount of upper airway distention in lambs and differences in inspiratory and expiratory tidal volume before and after intubation.
  
  
  RESULTS
  In lambs, the combined trachea and oropharynx contributed to 14 (12-21) % (median (IQR), whereas the oropharynx contributed to 9 (7-10) % of the total tidal volume measured at the mouth. In preterm infants, inspiratory (11.1 (7.9-22.6) mL/kg vs 5.8 (3.9-9.6) mL/kg (p=0.01)) and expiratory (8.3 (6.8-15.4) mL/kg vs 4.9 (3.9-9.6) mL/kg (p=0.02)) tidal volumes were significantly larger during mask ventilation compared with endotracheal ventilation. Leak was 18.7 (3.3-28.7) % before versus 0 (0-2.3) % after intubation (p<0.0001). Delta pressure was 23.7 (20.8-25.6) cm H2O before versus 24.8 (20.8-26.0) cm H2O after intubation (p>0.05). During mask ventilation, expiratory tidal volume increased from 10.0 (5.4-15.6) mL/kg to 11.3 (7.6-17.0) mL/kg (p=0.01), but remained unchanged during endotracheal ventilation.
  
  
  CONCLUSIONS
  During neonatal mask ventilation, distention of the upper respiratory tract contributes to the tidal volumes measured and should be taken into account when targeting tidal volumes during mask ventilation.
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: van Vonderen
authors.affiliation: The Ritchie Centre, Monash Institute for Medical Research, Monash University, Melbourne, Victoria, Australia.
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Hooper
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Vera B
authors.initials: VB
authors.lastname: Krabbe
authors.affiliation: The Ritchie Centre, Monash Institute for Medical Research, Monash University, Melbourne, Victoria, Australia.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Siew
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Arjan B
authors.initials: AB
authors.lastname: Te Pas
mesh_terms: D000818:Animals; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D007442:Intubation, Intratracheal; D017214:Laryngeal Masks; D008297:Male; D009960:Oropharynx / Q000502:physiology; D012756:Sheep; D014691:Ventilation
keywords: endotracheal ventilation; face mask ventilation; neonate; tidal volume