Upper airway radiographs in infants with upper airway insufficiency

Upper airway measurements in nine infants considered to be at risk of upper airway insufficiency, six of whom presented after an apnoeic episode, were compared with measurements taken in two age groups of healthy infants. Paired, inspiratory and expiratory, lateral upper airway radiographs were obtained while the infants were awake and breathing quietly. The radiographs of all nine infants demonstrated narrowing in the oropharyngeal portion of the airway during inspiration and in six infants there was ballooning ofthe upper airway during expiration. Seven of the nine infimts subsequently experienced recurrent apnoeic episodes which required vigorous stimulation to restore breathing. Experience suggests that respiratory phase timed radiographs are a useful adjunct to the evaluation of infants who are suspected of having upper airway dysfunction. They provide information regarding both the dimensions and compliance of the upper airway as well as the site of any restriction. (Arch Dis Child 1994; 70: 523-529) Cot Death Association (a division ofthe National Children's Health Research Foundation) and Department of Paediatrics, University ofAuckland, Auckland, New Zealand S L Tonkin S L Davis T R Gunn Correspondence to: Dr S L Tonkin, Cot Death Association, 5 Clonbem Road, PO Box 28177, Auckland, New Zealand. Accepted 12 January 1994 Infants with upper airway dysfunction may be at increased risk for sudden infant death syndrome (SIDS).1 2 To date there has been no reliable way in the neonatal period to identify infants who may subsequently experience significant upper airway obstruction. Clinical signs of inspiratory intercostal and lateral pharyngeal indrawing in infants who are free of pulmonary disease indicate that increased upper airway resistance is likely in such infants. In the obstructive sleep apnoea syndrome of adults and children, airway obstruction results from collapse of the oropharynx during inspiration as shown in studies using flexible fibro-optic endoscopy3 and pharyngeal pressure recordings.4 Partial upper airway obstruction may also be demonstrated by these techniques. Both endoscopy and pressure recordings are invasive procedures and are not available in all paediatric services for the clinical evaluation of infants. In a previous report we have shown that measurement of the upper airway in lateral neck radiographs taken during specific phases of the respiratory cycle is feasible when the x ray machine is triggered by a monitor that detects respiratory movement. In a group of healthy infants the dimensions ofthe upper airway were documented during inspiration and during expiration, in the newborn period and at 6 weeks of age using this method.5 We now report similarly obtained upper airway measurements in nine infants at risk of upper airway insufficiency, seven of whom subsequently demonstrated significant apnoea. Subjects and methods There were nine infants in this study, six were referred after apparent life threatening events (ALTEs). One infant with Pierre Robin syndrome was identified in the neonatal period because he had a very small jaw and the other neonate because of noisy breathing. One older infant was referred for noisy breathing. None of these infants had lower respiratory tract disease. These nine infants who presented with symptoms suggestive of upper airway dysfunction has inspiratory and expiratory lateral upper airway radiographs as in our previous study.5 These were obtained with each infant lying on the side with the head in the lateral position and the line from the infraorbital margin to the external auditory canal at a right angle to the spine. All infants were in a quiet awake or drowsy state after being fed and were unsedated. It is important to note that measurements of radiographs taken during crying fail to demonstrate a difference in airway size between the two respiratory phases. The upper airway from below the larynx to the base of the skull including the nasion was imaged. The film was placed in the bucky with anode to film distance 100 cm. The exposures were timed by the use of a modified Graseby (Graseby Medical Ltd) MR1O apnoea monitor. The capsule of the monitor was taped to the infant's abdomen at the level of the umbilicus. The current pulse to the breath indicator light of the Graseby monitor was used to trigger the x ray machine such that exposure was made at the end of the first 20% of inspiratory movement time for the inspiratory film, and midway between successive inspiratory movements for the expiratory film. The amount ofx radiation exposure per pair of films was equivalent to two chest radiographs. All radiographs were obtained under these standard conditions and measurements were made with no correction for cephalometric readings. Cephalometric measurements made from the films included three distances (nasion to sella, nasion to upper jaw, nasion to lower jaw) and three angles (sella-nasion-upper jaw, sella-nasion-lower jaw, upper jaw-nasionlower jaw) as illustrated in fig 1, the radiograph of the infant with Pierre Robin syndrome (case 2). Upper airway measurements included the distance between anterior and posterior airway walls along the lines, gnathion to anterior sella 523 group.bmj.com on May 3, 2017 Published by http://adc.bmj.com/ Downloaded from