Shirley L. Tonkin

Neonatal micrognathia is associated with small upper airways on radiographic measurement

In order to determine if infants with clinical micrognathia identified in the newborn period have smaller upper airways than do normal infants, and if their airway size is related to risk of later apnoea, respiration‐timed upper airway radiographic measurements were performed in 21 asymptomatic neonates with clinical micrognathia. Their radiographic measurements were compared with those of a previously reported cohort of 35 normal infants. The micrognathic infants and a control group of 27 infants referred for parental anxiety were followed for 6 mo on home apnoea monitors. Sleep apnoea at home requiring stimulation by the parents occurred in 6 of 7 infants with micrognathia associated with craniofacial anomalies, 9 of 14 (64%) infants with isolated micrognathia, but only 1 of the 27 control infants (p < 0.001). Upper airway measurements at term of the infants with isolated micrognathia who later experienced apnoea were significantly smaller than either those of normal infants (p < 0.01) or of micrognathic infants who did not have apnoea requiring stimulation (p < 0.05). In conclusion, upper airway measurements on timed lateral radiographs in asymptomatic micrognathic infants at term (corrected age) revealed them to be smaller than those of normal infants. Narrower upper airways were associated with increased risk of subsequent apnoea requiring stimulation.

Randomized Controlled Trial of a Car Safety Seat Insert to Reduce Hypoxia in Term Infants

OBJECTIVE: To test the hypothesis that a foam plastic insert that allows the infant head to rest in a neutral position in sleep may prevent obstruction of the upper airway and thus reduce episodes of reduced oxygenation in term infants in car seats. METHODS: Healthy full-term babies were randomized to be studied during sleep while restrained in an infant car safety seat either with or without the insert, with continuous polysomnographic recordings with sleep video. RESULTS: Seventy-eight infants (39 in each group) had polysomnogram recordings at a mean of 8 days of age. Both groups showed a small fall in mean hemoglobin oxygen saturation (SpO2) over the first hour of sleep. There was no difference between insert and no insert in the rate of moderate desaturations (a fall in SpO2 ≥4% lasting for ≥10 seconds, mean ± SEM, 17.0 ± 1.5 vs 17.2 ± 1.5/hour), or mean SpO2 during sleep. The insert was associated with a significant reduction in the rate of obstructive apnea (0.3 ± 0.1 vs 0.9 ± 1.5/hour, P < .03), the severity of desaturation events (minimum SpO2 82% ± 1% vs 74% ± 2%, P < .001), and time with SpO2 <85% (0.6% ± 0.3% vs 1.8% ± 1.4%, P = .03). CONCLUSIONS: In full-term newborn infants, a car seat insert that helps the head to lie in a neutral position was associated with reduced severity of desaturation events but not the overall rate of moderate desaturations.

Effect of pacifier use on mandibular position in preterm infants.

Aim: It has been hypothesized that the association of pacifier use with reduced risk of sudden infant death is mediated by forward movement of the mandible and tongue that helps open the upper airway. Our aim was to examine whether the mandible is moved forward when an infant is sucking on a pacifier, and if so, whether the mandible remains advanced after the pacifier is removed.

Can we reduce episodes of haemoglobin desaturation in full‐term babies restrained in car seats?

Objectives: To determine whether episodes of haemoglobin oxygen (SpO2) desaturation in full‐term infants restrained in car seats can be reduced by a simple foam plastic infant car seat insert designed to push the body forward, with space for the protuberant occiput to lie behind the spine, and so reduce flexion of the infants head on the trunk.

Failure of mouth-to-mouth resuscitation in cases of sudden infant death

We describe two cases of sudden infant death syndrome (SIDS) and one case of apparent life threatening apnoea where resuscitation was attempted by the mouth-to-mouth route. This was associated with evidence of gastric distension, including reflux of milk into the airway in the first two cases. In the second case the mother used mouth-to-mouth breathing after finding that she could not cover her babys nose-and-open-mouth with her mouth. In the last case, the mother went on to try the mouth-to-nose route, with a good outcome. Systematic documentation of the route of resuscitation and its outcome in all cases of SIDS and near-miss SIDS may provide valuable insights into the optimal route for infant resuscitation.

Does tongue size contribute to risk of airway narrowing in preterm infants sitting in a car safety seat

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). CONCLUSION 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.

Upper airway size while sucking on a pacifier in an infant with micrognathia.

Abstract:  In an infant with micrognathia, who was being evaluated after an apparent life‐threatening event, respiration timed lateral radiographs showed an increase in the width of the middle airway space during inspiration from 2 mm without the pacifier to 9 mm while sucking on a pacifier. This observation is consistent with the hypothesis that the well‐documented association between the pacifier use and reduced risk of sudden infant death syndrome may be at least in part related to changes in airway size.

Are baby hammocks safe for sleeping babies? A randomised controlled trial

Two reports of infants found dead after sleeping in baby hammocks have raised international concern about the safety of infant hammocks. We therefore tested whether hammock sleep affected oxygenation in infants, when they were at an age of high risk of sudden, unexpected infant death.

A view from New Zealand: comments on the prolonged QT theory of SIDS causation.

* Abbreviations: ECG = : electrocardiogram • SIDS = : sudden infant death syndrome The article by Schwartz et al1 published in the New England Journal of Medicine reports on electrocardiographic (ECG) measurements made over a period of 18 years on infants on the 3rd day of life. It identifies those infants previously studied who died suddenly and unexpectedly and were diagnosed as having died of sudden infant death syndrome (SIDS), and compares their ECGs with those of the survivors. The idea that SIDS may be related to dysrhythmic events, the predisposing factor being an abnormally long QT interval, is one that at least merits attention. However, there are problems with any investigation whose basis relies on measurement of the QT interval as the authors admit. These problems include the possibility of including U waves in the measurement, the validity of using standard formula to calculate the QTc, and how one should deal with the variation of the QT interval with variation in heart …