Assessment of inspiratory flow limitation in children with sleep-disordered breathing by a nasal cannula pressure transducer system

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Abstract
A nasal cannula pressure transducer system identifies inspiratory flow limitation and increased upper airway resistance in adults with sleep‐disordered breathing (SDB). The purpose of this study was to evaluate whether nasal cannula pressure (NCP) detects apneas and hypopneas as well as additional flow‐limited events associated with increased airway resistance in children. We studied NCP in 47 patients (ages 2–14 years) referred for SDB to a university‐based sleep disorders program during nocturnal polysomnography (NPSG). During NPSG, airflow was assessed simultaneously by thermistor and NCP. There was a high correlation between apneas assessed by thermistor (T) and NCP (r = 0.90, P < 0.0001), and for hypopneas using these two methods (r = 0.94, P = 0.0001). Respiratory driving pressure was indirectly measured with an esophageal pressure catheter. Flow‐limited (flattened) NCP waves were associated with significantly higher driving pressure, indicating elevated upper airway resistance, compared to nonflow‐limited (rounded) waves during nonrapid eye movement (NREM) (P = 0.05) and rapid eye movement (REM) (P = 0.01) sleep. Patients were classified as either having obstructive sleep apnea syndrome (OSAS) or primary snoring, based on standard NPSG criteria. NCP identified additional respiratory events with a flattened contour (FC) not detected by thermistor. NCP is a noninvasive device that identifies obstructive apneas and hypopneas as well as additional respiratory events associated with flow limitation in children. Pediatr Pulmonol. 2002; 33:380–387.