The effect of rapid eye movement (REM) sleep on upper airway mechanics in normal human subjects

Abstract

It has been proposed that the upper airway is more compliant during rapid eye movement (REM) sleep than during non‐rapid eye movement (NREM) sleep. The purpose of this study was to test this hypothesis in a group of subjects without sleep‐disordered breathing. On the first night, the effect of sleep stage on the relationship of retropalatal cross‐sectional area (CSA; visualized with a fibre‐optic scope) to pharyngeal pressure (PPH) measured at the soft palate during eupnoeic breathing was studied. Breaths during REM sleep were divided into phasic (associated with eye movements) and tonic (not associated with eye movements). There was a significant decrease in pharyngeal CSA during NREM sleep compared with wakefulness. There was no further decrease observed during either tonic or phasic REM sleep. Pharyngeal compliance, defined as the slope of the regression CSA versus PPH, was significantly increased during NREM sleep compared with wakefulness and REM sleep, with the compliance during both tonic and phasic REM sleep being similar to that observed in wakefulness. On the second night, the effect of sleep stage on pressure‐flow relationships of the upper airway was investigated. There was a trend towards the upper airway resistance being highest in NREM sleep compared with wakefulness and REM sleep. We conclude that the upper airway is stiffer and less compliant during REM sleep than during NREM sleep. We postulate that this difference is secondary to differences in upper airway vascular perfusion between REM and NREM sleep.

Inhibition of ventilatory motor output increases expiratory retro palatal compliance during sleep

“…Our laboratory and others have utilized and validated FOB in multiple studies (Rowley et al, 1998; Rowley et al, 2002; Sankri-Tarbichi et al, 2009). To mitigate these limitations, we determined and fixed the locations of the scope and the catheter to the nasal mask after locating the retro palatal space.…”

“…The absolute value of retro palatal CSA was obtained from five different phases of the respiratory cycle (B I : beginning inspiration, P I : peak inspiration, E I /B E : end inspiration and beginning expiration, P E : peak expiration, E E : end expiration) by manually outlining the retro palatal lumen using computer software (Sigma Scan, Jandel) in mm 2 (Figure 2). The ability to reproduce this technique has been previously validated by our laboratory (Morrell et al, 1998a; Morrell et al, 1998b; Rowley et al, 1998; Rowley et al, 2002). For each image, the scanning software provided an area in pixels.…”

“…For each image, the scanning software provided an area in pixels. We converted these relative areas to absolute areas by using the dimensions of the pressure catheter as a reference (Rowley et al, 1998; Rowley et al, 2002; Sankri-Tarbichi et al, 2009). …”

Sleep & Breathing

“…We also showed that the sleep-related narrowing was greater in patients with obstructive sleep apnoea compared with healthy subjects and in obese relative to thin patients . During REM sleep, the pattern of airway narrowing is similar, although the magnitude of the changes were smaller than those that occurred during non-REM sleep (Rowley et al 1998).…”

“…We also showed that the sleep-related narrowing was greater in patients with obstructive sleep apnoea compared with healthy subjects and in obese relative to thin patients . During REM sleep, the pattern of airway narrowing is similar, although the magnitude of the changes were smaller 68 than those that occurred during non-REM sleep (Rowley et al 1998).Pharyngeal transmural pressure can also be affected by sleep-related changes in extraluminal pressure. In normal subjects and in patients with obstructive sleep apnoea, our group have found that complete pharyngeal occlusion occurred during spontaneous and induced central sleep apnoeas (Badr et al 1995), i.e.…”