Mouth Breathing in Obstructive Sleep Apnea prior to and during Nasal Continuous Positive Airway Pressure

Abstract

Background: Patients with obstructive sleep apnea syndrome (OSAS) often complain of dryness of mouth and throat prior to and during nasal continuous positive airway pressure (nCPAP). It is believed that this is due to mouth breathing (MB). However, the association between mouth breathing and apneas/hypopneas and the effect of CPAP on MB has not been studied. Objectives: The purpose of the present study was, therefore, to assess the frequency and duration of episodes of MB prior to and during treatment with nCPAP. Methods: MB was recorded prior to and during nCPAP with a closely fitting mouth mask connected to a pneumotachograph and nasal flow was measured via nasal prongs. MB episodes were expressed as the number of events divided by total sleep time × 60, to give the MB event index per hour of sleep. MB time divided by total sleep time × 60 was calculated in minutes to get the MB time index per hour of sleep. Patients: Eleven male patients with OSAS (mean age 57.9 ± 8.3 years, body mass index 30.2 ± 3.8) were recruited to the study. Results: Prior to nCPAP, the apnea/hypopnea index was 55.8 ± 26 and decreased during nCPAP to 8.0 ± 3.4. The lowest SaO₂ measured was 82.9 ± 4.7%, and increased to 87.5 ± 2.7% under nCPAP. The mean nCPAP was 7.8 ± 1.6 cm H₂O. MB event index per hour of sleep decreased from 35.2 ± 19.7 prior to treatment to 5.0 ± 5.2 under nCPAP (p < 0.01). In 52.2 ± 27.4% of obstructive respiratory events, MB started at the end of an apnea/hypopnea episode, decreasing to 8.5 ± 12.5% with nCPAP treatment. MB time index per hour of sleep was reduced from 13.5 ± 10.2 min prior to treatment to 4.6 ± 5.5 min under nCPAP (p < 0.05). Conclusions: In OSAS patients, MB episodes often appear at the termination of an apnea/hypopnea episode. In many cases, MB episodes can be markedly reduced by nCPAP treatment. When patients on nCPAP complain of dry mouth, appropriate measurements should be performed to verify MB.

Frequency of Upper Airway Symptoms before and during Continuous Positive Airway Pressure Treatment in Patients with Obstructive Sleep Apnea Syndrome

“…Humidity of inhaled air increases to 80–100% as it passes through the nasal cavity [24]. Although breathing during sleep is normally nasal rather than oral [25], OSAS patients often breathe through the mouth and this may cause dryness of the mouth and throat [26]. Exhalation through the mouth prevents the return of humidity from the lower airways back to the nasal mucosa.…”

Quality of life, compliance, sleep and nasopharyngeal side effects during CPAP therapy with and without controlled heated humidification

“…If this occurs frequently, therapy acceptance is impaired [1]. During continuous positive airway pressure (CPAP) the palatal seal, by which the uvula closes the nasopharynx, is not always complete, causing relevant leaks to develop which last several minutes [2]. Since sleep and quality of life (QOL) are affected by the side effects of dryness in the upper respiratory tract associated with CPAP, it is recommended that the humidity and temperature of inspired air should be increased by heated humidification (HH).…”

Oral health in patients treated by positive airway pressure for obstructive sleep apnea: a population-based case–control study

“…In this perspective, mouth breathing associated with OSA may be the mediating factor that predisposes to the development of gingivitis and periodontitis [8]. In CPAP/BiPAP-treated patients, mouth breathing is significantly reduced due to the nasal or mouth mask wearing during sleep [31]. Moreover, CPAP/BiPAP devices with heated humidification and facemask are proved to prevent upper airway dryness during the treatment [32].…”