title: Redesign of an Open-System Oxygen Face Mask With Mainstream Capnometer for Children.
abstract: BACKGROUND
  Partial pressure of end-tidal carbon dioxide (PETCO2) monitoring in children is important to detect apnea or hypopnea early to intervene before hypoxemia develops. Monitoring PETCO2in children without a tracheal tube is challenging. To improve PETCO2measurement accuracy in a commercially available mask with a mainstream CO2detector, we implemented design changes with deform-and-hold shaping technology and anterior-posterior adjustment of the expiratory gas flow cup.
  
  
  METHODS
  Two sizes of redesigned face masks (small for 7-20 kg, medium for 10-40 kg) were evaluated. Initial bench testing used a simulator modeling a spontaneously breathing infant and child with a natural airway. An infant/child manikin head was connected to the breathing lung simulator. A mass flow controller provided expiratory CO2. Mask fit was then evaluated on healthy human subjects to identify anatomical features associated with good fit, defined as square shape capnography waveform during expiration. A 3-dimensional digital scan was used to quantify anatomical features. The gaps between face mask rims and facial surface were manually measured.
  
  
  RESULTS
  Bench testing revealed a PETCO2difference of 3.4 ± 1.5 mm Hg between a measured PETCO2by the redesigned mask and CO2concentration at trachea, as compared with 6.7 ± 6.2 mm Hg between PETCO2measured by nasal cannula and trachea (P < .001). In the human mask fit study, 35 children (13 ± 4 kg) with the small mask and 38 (24 ± 8 kg) with the medium mask were evaluated. Capnography tracing was successfully obtained in 86% of the small and 100% of the medium masks. In children with small-size masks, the gap between the face mask rim and the child's face was not statistically different among those with good mask fit and without (1.0 ± 1.5 mm vs 1.4 ± 1.9 mm, P = .73).
  
  
  CONCLUSIONS
  PETCO2measurement by a redesigned open-system face mask with a mainstream CO2detector was accurate in the bench setting. The redesigned face mask can attain good mask fit and accurate capnography tracings in the majority of infants and children.
authors.affiliation: Respiratory Therapy Department naplitanon@email.chop.edu.
authors.forename: Natalie
authors.initials: N
authors.lastname: Napolitano
authors.affiliation: Division of Anesthesiology and Critical Care Medicine.
authors.forename: Akira
authors.initials: A
authors.lastname: Nishisaki
authors.affiliation: Center for Simulation, Advanced Education and Innovation, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Hayley S
authors.initials: HS
authors.lastname: Buffman
authors.affiliation: Center for Simulation, Advanced Education and Innovation, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Jessica
authors.initials: J
authors.lastname: Leffelman
authors.affiliation: Division of Anesthesiology and Critical Care Medicine.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Maltese
authors.affiliation: Division of Anesthesiology and Critical Care Medicine.|Center for Simulation, Advanced Education and Innovation, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Vinay M
authors.initials: VM
authors.lastname: Nadkarni
mesh_terms: D001944:Breath Tests / Q000295:instrumentation; D019296:Capnography; D002245:Carbon Dioxide / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D004867:Equipment Design; D005260:Female; D006801:Humans; D007223:Infant; D008168:Lung / Q000502:physiology; D008297:Male; D008348:Manikins; D008397:Masks; D008954:Models, Biological; D009666:Nose; D010100:Oxygen / Q000008:administration & dosage*; D010313:Partial Pressure; D012891:Sleep Apnea Syndromes / Q000175:diagnosis; D014132:Trachea
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: capnography; fit; mask; noninvasive; oxygen; pediatrics