Mandibular Movements are a Reliable Noninvasive Alternative to Esophageal Pressure for Measuring Respiratory Effort in Patients with Sleep Apnea Syndrome

Abstract

Purpose Differentiation between obstructive and central apneas and hypopneas requires quantitative measurement of respiratory effort (RE) using esophageal pressure (PES), which is rarely implemented. This study investigated whether the sleep mandibular movements (MM) signal recorded with a tri-axial gyroscopic chin sensor (Sunrise, Namur, Belgium) is a reliable surrogate of PES in patients with suspected obstructive sleep apnea (OSA). Patients and Methods In-laboratory polysomnography (PSG) with PES and concurrent MM monitoring was performed. PSGs were scored manually using AASM 2012 rules. Data blocks (n=8042) were randomly sampled during normal breathing (NB), obstructive or central apnea/hypopnea (OA/OH/CA/CH), respiratory effort-related arousal (RERA), and mixed apnea (MxA). Analyses were evaluation of the similarity and linear correlation between PES and MM using the longest common subsequence (LCSS) algorithm and Pearson’s coefficient; description of signal amplitudes; estimation of the marginal effect for crossing from NB to a respiratory disturbance for a given change in MM signal using a mixed linear-regression. Results Participants (n=38) had mild to severe OSA (median AH index 28.9/h; median arousal index 23.2/h). MM showed a high level of synchronization with concurrent PES signals. Distribution of MM amplitude differed significantly between event types: median (95% confidence interval) values of 0.60 (0.16–2.43) for CA, 0.83 (0.23–4.71) for CH, 1.93 (0.46–12.43) for MxA, 3.23 (0.72–18.09) for OH, and 6.42 (0.88–26.81) for OA. Mixed regression indicated that crossing from NB to central events would decrease MM signal amplitude by –1.23 (CH) and –2.04 (CA) units, while obstructive events would increase MM amplitude by +3.27 (OH) and +6.79 (OA) units (all p<10 −6 ). Conclusion In OSA patients, MM signals facilitated the measurement of specific levels of RE associated with obstructive, central or mixed apneas and/or hypopneas. A high degree of similarity was observed with the PES gold-standard signal.

Respiratory effort during sleep and prevalent hypertension in obstructive sleep apnoea

“…MJM signal automated machine learning algorithms were trained with a large number of fragments obtained from periods of normal breathing and epochs that included the full spectrum of obstructive events (RERAs, obstructive apnoeas, obstructive hypopnoeas and mixed episodes) and central events. Details of absolute values generated by the Sunrise system have been reported previously [ 27 ].…”

“…In-laboratory polysomnography (PSG) was recorded with a digital acquisition system (Somnoscreen Plus, Somnomedics, Rander-sacken, Germany of per hour was sufficient to diagnose OSA, even in the absence of associated symptoms or disorders [30]. The conventional rules for severity grading based on AHI were used to categorize into non-OSA (<5), mild (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), moderate (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and severe OSA (>30) [12].…”

“…We have previously demonstrated that mandibular jaw movements (MJM) during sleep provide powerful information about RE and sleep time spent in increased RE [26,27]. In normal physiological sleep, the mandibular jaw slightly moves a few tenths of a millimetre at the breathing frequency around a fixed position and the mouth is almost closed.…”

“…The lack of data on the cardiovascular impact of increased respiratory effort can be partly explained by the challenge of assessing and measuring the proportion of TST spent with increased respiratory effort. We have previously demonstrated that mandibular jaw movements (MJM) during sleep provide powerful information about respiratory effort and sleep time spent with increased respiratory effort [ 26 , 27 ]. In normal physiological sleep, the mandibular jaw slightly moves a few tenths of a millimetre at the breathing frequency around a fixed position and the mouth is almost closed.…”

“…This sleep physiological displacement is controlled by the respiratory and pre-motor trigeminal nuclei, and reflects respiratory drive and variations in respiratory efforts. MJM therefore reflects respiratory drive level and efforts as a function of variations in upper airway resistance that typically occur during abnormal respiratory events [ 26 , 27 ].…”