Objective. To determine whether upper airway resistance syndrome (UARS) can be recognized and distinguished from obstructive sleep apnea syndrome (OSAS) in prepubertal children based on clinical evaluations, and, in a subgroup of the population, to compare the efficacy of esophageal pressure (Pes) monitoring to that of transcutaneous carbon dioxide pressure (tcPco2) and expired carbon dioxide (CO2) measurements in identifying UARS in children.
Study Design. A retrospective study was performed on children, 12 years and younger, seen at our clinic since 1985. Children with diagnoses of sleep-disordered breathing were drawn from our database and sorted by age and initial symptoms. Clinical findings, based on interviews and questionnaires, an orocraniofacial scale, and nocturnal polygraphic recordings were tabulated and compared. If the results of the first polygraphic recording were inconclusive, a second night's recording was performed with the addition of Pes monitoring. In addition, simultaneous measurements of tcPco2 and endtidal CO2 with sampling through a catheter were performed on this second night in 76 children. These 76 recordings were used as our gold standard, because they were the most comprehensive. For this group, 1848 apneic events and 7040 abnormal respiratory events were identified based on airflow, thoracoabdominal effort, and Pes recordings. We then analyzed the simultaneously measured tcPCo2 and expired CO2 levels to ascertain their ability to identify these same events.
Results. The first night of polygraphic recording was inconclusive enough to warrant a second recording in 316 of 411 children. Children were identified as having either UARS (n = 259), OSAS (n = 83), or other sleep disorders (n = 69). Children with small triangular chins, retroposition of the mandible, steep mandibular plane, high hard palate, long oval-shaped face, or long soft palate were highly likely to have sleep-disordered breathing of some type. If large tonsils were associated with these features, OSAS was much more frequently noted than UARS. In the 76 gold standard children, Pes, tcPco2, and expired CO2 measurements were in agreement for 1512 of the 1848 apneas and hypopneas that were analyzed. Of the 7040 upper airway resistance events, only 2314 events were consonant in all three measures. tcPco2 identified only 33% of the increased respiratory events identified by Pes; expired CO2 identified only 53% of the same events.
Conclusions. UARS is a subtle form of sleep-disordered breathing that leads to significant clinical symptoms and day and nighttime disturbances. When clinical symptoms suggest abnormal breathing during sleep but obstructive sleep apneas are not found, physicians may, mistakenly, assume an absence of breathing-related sleep problems. Symptoms and orocraniofacial information were not useful in distinguishing UARS from OSAS but were useful in distinguishing sleep-disordered breathing (UARS and OSAS) from other sleep disorders. The analysis of esophageal pressure patterns during sleep was the most revealing of the three techniques used for recognizing abnormal breathing patterns during sleep.
Sleep-disordered breathing and comorbidities: role of the upper airway and craniofacial skeleton
