Elsevier

American Journal of Otolaryngology

Volume 36, Issue 2, March–April 2015, Pages 173-177
American Journal of Otolaryngology

Original contribution
Middle ear pressure during sleep and the effects of continuous positive airway pressure

https://doi.org/10.1016/j.amjoto.2014.10.024Get rights and content

Abstract

Purpose

Prior studies evaluating Eustachian tube physiology, baseline middle ear pressure (MEP), and the effects of continuous positive airway pressure (CPAP) have been performed on awake patients. No study to date has specifically investigated MEP during sleep despite the fact that the average individual spends a third of their lifetime sleeping. The primary objectives of the current study are to quantify normal physiologic MEP during sleep and to evaluate the effects of escalating CPAP levels.

Materials and methods

Prospective observational study at a tertiary academic referral center evaluating serial tympanometry on sleeping adult patients during polysomnography. MEP was recorded awake, at 1-hour intervals during diagnostic polysomnography, and at all CPAP levels during titration. Changes in MEP with duration of sleep and escalating CPAP levels were analyzed.

Results

Ten adults were included (4 females; 6 males; mean age 58 years). The mean MEP while awake was 3 decapascals (daPa). The mean MEP during sleep without CPAP rose steadily from 14 daPa at 1 hour to 41 daPa at 4 hours (r = 0.52; p < 0.001). The mean MEP during sleep at a CPAP level of 5 cm of water was 54 daPa. The mean MEP rose steadily with increasing CPAP levels, and was 104 daPa at 10 cm of water, (r = 0.82; p < 0.001). The mean MEP during sleep without CPAP was 26 daPa, which was significantly lower than the mean MEP during sleep with CPAP between 5–10 cm H2O (p < 0.01).

Conclusions

MEP naturally increases with duration of sleep. CPAP therapy causes a supraphysiologic elevation in MEP that rises with increasing pressure levels. These findings may help guide future studies examining the safety of CPAP following otologic surgery and the potential therapeutic benefit in patients with chronic middle ear disease.

Introduction

Maintenance of normal middle ear pressure (MEP) by an appropriately functioning eustachian tube (ET) is vital to the health of the middle ear. ET dysfunction resulting in chronic negative MEP has been implicated in many significant otologic conditions including hearing loss, tympanic membrane (TM) retraction, and chronic otitis media. Prior studies evaluating middle ear and ET physiology have been performed on awake patients with normal or negative MEP [1], [2], [3]. To the authors’ knowledge, no study to date has specifically investigated MEPs during sleep despite the fact that the average individual sleeps nearly a third of their lifetime. Many organ systems have normal physiologic changes during sleep. In patients without middle ear disease, studies have shown that MEP is most commonly positive upon waking, but quickly normalizes toward zero after swallowing and chewing maneuvers [1], [2], [3]. These findings suggest that middle ear and ET physiology also change during sleep.

Continuous positive airway pressure (CPAP) therapy, a highly effective treatment for obstructive sleep apnea (OSA), provides a pneumatic stent for the upper airway and prevents apnea during sleep. It is highly plausible that positive pressure may be transmitted to the middle ear through the ET during CPAP use. This can occur during periodic ET opening or when nasopharyngeal airway pressures exceed the resting pressure keeping the ET closed. A recent study demonstrated a linear increase in MEP with increasing CPAP levels in awake patients [4]. We hypothesized that MEP would rise slowly with duration of sleep and that escalating CPAP levels would cause proportional elevations in MEP during sleep.

Section snippets

Materials and methods

Following Institutional Review Board approval (IRB No. 12-005787), adult patients undergoing polysomnography at a tertiary academic referral center were prospectively enrolled. All research subjects were provided informed consent. Study participation was limited to patients without prior middle ear disease or a history of otologic surgery. Each eligible participant was further screened using otomicroscopy and tympanometry (Madsen OTOflex 100; GN Otometrics North America, Schaumburg, IL), and

Results

Ten patients, six men and four women, were included. The mean age at testing was 57.8 years (range 37.7–74.7 yrs). Monaural testing was performed in each patient including six left and four right ears. The mean MEP of all patients before sleep was + 3 daPa [range, − 12 to + 18 daPa; standard deviation (SD), ± 10]. The mean MEP at 1, 2, 3, and 4 hours following sleep onset were + 14 daPa (range, − 15 to + 40 daPa; SD, ± 24), + 22 daPa (range, − 1 to + 64 daPa; SD, ± 23), + 27 daPa (range, − 9 to + 53 daPa; SD, ± 

Discussion

Using a novel method to record MEP during sleep, our results confirm the hypothesis that MEP predictably rises during sleep. We found that the mean MEP after 4 hours of sleep was 41 daPa, which corroborates two earlier studies measuring an average MEP of 29 and 48 daPa immediately upon waking [1], [2]. These values are significantly higher than the mean awake MEP of 3 daPa in the current study.

The mechanism of increased MEP during sleep is likely multifactorial and may result, in part, from

Conclusions

Middle ear pressure rises proportionately with duration of sleep. Furthermore, increasing CPAP levels result in predictable supraphysiologic elevations in MEP. Further research is needed to examine the long-term consequences of CPAP use on the middle ear and the potential therapeutic benefits for patients with tympanic membrane retraction and chronic ear disease.

References (15)

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IRB Approval Number: 12-005787.

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