title: Does tongue size contribute to risk of airway narrowing in preterm infants sitting in a car safety seat?
abstract: BACKGROUND
  Preterm infants are at risk of narrowing of the upper airway while restrained in infant car seats, leading to secondary apnea. However, some infants are able to maintain a normal airway. We hypothesized that this might reflect relatively smaller tongue size.
  
  
  METHODS
  We retrospectively analyzed previously reported respiration-timed lateral radiographs of the upper airways of 17 preterm infants ready for discharge (32.6 ± 1.0 weeks gestation at birth, and 37.8 ± 9.7 days old at study) taken during sleep, first in a car safety seat with an insert that allowed the head to remain upright, and then without the insert, when the head slumped forward. The presence of air above the tongue was used as an index of relative tongue size.
  
  
  RESULTS
  A smaller airspace around the tongue (relatively larger tongue) was associated with greater narrowing of the upper airway when the head was flexed forward in sleep (p < 0.002). In contrast, there was no significant correlation between baseline airway size and change in airway size (r (2) = 0.16, p = 0.11).
  
  
  CONCLUSIONS
  The present study supports the hypothesis that the vulnerability of preterm infants to airways compromise while restrained in a car safety seat may be in part related to relative tongue size.
authors: Department of Physiology, University of Auckland, Auckland, New Zealand.
authors: S L
authors: SL
authors: Tonkin
authors: Department of Physiology, University of Auckland, Auckland, New Zealand.
authors: C
authors: C
authors: McIntosh
authors: Department of Physiology, University of Auckland, Auckland, New Zealand.
authors: A J
authors: AJ
authors: Gunn
mesh_terms: D000402:Airway Obstruction / Q000000981:diagnostic imaging / Q000209:etiology*; D057207:Child Restraint Systems; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D009929:Organ Size; D010614:Pharynx / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011187:Posture; D011859:Radiography; D012189:Retrospective Studies; D012890:Sleep; D014059:Tongue / Q000033:anatomy & histology* / Q000000981:diagnostic imaging