Partial upper airway obstruction during sleep. Studies with the static charge-sensitive bed (SCSB)

Nocturnal respiration, the ballistocardiogram, and body movement activity were studied with the static charge-sensitive bed (SCSB) in snorers who represented a wide range of severity of sleep-related upper airway obstruction. The emphasis was to evaluate the performance of the SCSB as a noninvasive tool for assessing nocturnal breathing disturbances. The results show that periodic episodes of obstructive apnea or hypopnea can reliably be monitored with the method. Additional breathing abnormalities suggesting the presence of increased respiratory resistance and increased body motility were frequently observed not only in OSAS patients but also in snorers without apnea. Permanent morphological abnormalities of the upper airways were observed in pharyngeal CT in patients with OSAS but also in subjects with severe partial obstruction without apnea. The findings in the SCSB recordings clearly illustrate that there is a functional continuum from partial to complete upper airway obstruction during sleep. However, the structural differences of the upper airways observed between subjects with partial airway obstruction and with OSAS suggest that partial obstruction without apnea cannot always be considered as heralding the development of the OSAS, but rather as a separate entity, which may produce the same clinical signs and symptoms as in the OSAS. The SCSB turned out to be a simple but sensitive method to detect complete and partial upper airway obstruction during sleep. The SCSB may optimally yield information beyond reach of more complex recording systems. Nonapneic SCSB findings may have particular significance for the evaluation of preclinical stages of sleep-related upper airway obstruction.