Oral Flow Research Articles

Relationship between Oral Flow Patterns, Nasal Obstruction, and Respiratory Events during Sleep.

Sleep breathing patterns are altered by nasal obstruction and respiratory events. This study aimed to describe the relationships between specific sleep oral flow (OF) patterns, nasal airway obstruction, and respiratory events. Nasal flow and OF were measured simultaneously by polysomnography in 85 adults during sleep. OF was measured 2 cm in front of the lips using a pressure sensor. OF could be classified into three patterns: postrespiratory event OF (postevent OF), during-respiratory event OF (during-event OF), and spontaneous arousal-related OF (SpAr-related OF). Postevent OFs begin at the end of airflow reduction, are preceded by respiratory arousal, and are accompanied by postapneic hyperventilation; during-event OFs occur during nasal flow reduction; and SpAr-related OFs to OF begin during stable breathing, and are preceded by spontaneous arousal but are rarely accompanied by apnea/hypopnea. Multivariate regression showed that nasal obstruction was predictive of SpAr-related OF. The relative frequency of SpAr-related OF events was negatively correlated with the apnea-hypopnea index. The fraction of SpAr-related OF duration relative to total OF duration was significantly greater in patients with nasal obstruction than in those without. SpAr-related OF was associated with nasal obstruction, but not respiratory events. This pattern thus functions as a "nasal obstruction bypass", mainly in normal subjects and patients with mild sleep disordered breathing (SDB). By contrast, the other two types were related to respiratory events and were typical patterns seen in patients with moderate and severe SDB.

Relationship between Oral Flow Patterns, Nasal Airway, and Respiratory Events

Objectives: Few investigations have examined oral flow (OF) patterns during sleep. This study aimed to clarify the relationship between OF patterns, nasal airway obstruction, and obstructive respiratory events. Methods: Nasal flow and OF were measured separately by polysomography. OF was measured 2 cm in front of the lips using a pressure sensor. Subjects were categorized into 2 groups: those with nasal obstruction (n = 44) and those without nasal obstruction (n = 41). Results: OF could be divided into 3 patterns: postapneic OF, OF during flow reduction (OF during FR), and spontaneous arousal-induced OF (SpA-induced OF). Postapneic OF refers to OFs that begin at the end of obstructive respiratory events (eg, flow limitation, hypopnea, and apnea), are preceded by respiratory arousals, and are accompanied by postapneic hyperventilation. OF during FR refers to OFs that occur during respiratory event-like nasal flow reduction. SpA-induced OFs are OFs that begin during stable breathing, are preceded by spontaneous arousal but not accompanied by apnea or hypopnea. Multivariate regression analysis showed that nasal obstruction was predictive of SpA-induced OF. Only 1.3% of SpA-induced OF led to apnea or hypopnea. SpA-induced OF showed a negative correlation with the apnea-hypopnea index. Conclusions: Postapneic OF and OF during FR led to apnea or hypopnea and were typical patterns seen in patients with moderate and severe sleep-disordered breathing (SDB). By contrast, SpA-induced OF was not associated with apnea or hypopnea but functioned as a “nasal obstruction bypasser” seen mainly in normal subjects and patients with mild SDB.