Effect of Heated Humidification on Adherence to Continuous Positive Airway Pressure Therapy in Subjects With Obstructive Sleep Apnea and Nasopharyngeal Symptoms.

Numerous studies have demonstrated the efficacy of CPAP therapy for reducing symptoms (eg, daytime sleepiness), improving quality of life (QOL), reducing the risk of driving and occupational accidents, and preventing sequelae of obstructive sleep apnea (OSA), such as cardiovascular morbidity and mortality.1-3 Many patients have trouble complying with CPAP therapy even though it is effective.4 As many as 46–73% of patients undergoing nasal CPAP therapy report considerable local persistent side effects, such as congestion, burning, sneezing, or dryness,5,6 which can impair adherence to the therapy.7 As a result, patients perceive that the therapy will cause problems and consequently refuse it. Therefore, interventions to treat these side effects could improve adherence and provide better QOL. Heated humidification was developed for patients undergoing CPAP who experience chronic nasal congestion.4 The palatal seal, by which the uvula closes the nasopharynx, is not always complete during CPAP, leading to leaks.5 Mouth leaks during CPAP therapy seem to be particularly substantial, because use of CPAP can lead to elevated inspiratory air flow across the nasal and oral mucosa, because the nasal mucosa cannot compensate for the water transferred to inspired gases during expiration. Flow of cold air and mouth leaks through the nasal passage during nasal CPAP management generate a subjective sense of nose and mouth dryness, nasal congestion, and enhanced nasal resistance,6 which cause local nerves to secrete leukotrienes and vasoactive amines to increase nasal airway resistance7 leading to mouth breathing, a potent mechanism of oropharyngeal dryness.6 Oral dryness can change the oral flora and increase the risk for aspiration pneumonia.8 Heated humidification breaks the vicious circle produced by mouth leaks during nasal CPAP management in patients complaining of upper airway symptoms.9 Prior research has demonstrated that heated humidification prevents dehydration from CPAP with a nasal mask leak by increasing absolute humidity.7 A clinical consensus has been reached that humidifiers should be used to treat local side effects related to nasal CPAP management to enhance humidity and heat in respired air.6 Consensus statements and guidelines for noninvasive ventilation include contradictory recommendations regarding humidification.10,11 Humidity decreases congestion and dryness in patients with OSA, and heated humidification and cold pass-over humidity are frequently utilized to alleviate these symptoms. However, little is known about the effects of these kinds of humidity on adherence to CPAP therapy or nasal symptoms in patients with OSA. Heated humidification considerably improves daily adherence by 39 min, compared with that of cold pass-over humidification in patients with OSA.12 The greater adherence was due to the relatively high proportion of patients with nasal symptoms (eg, 58% dry throat and 60% nasal congestion before therapy). These crossover studies recommend that adherence to nasal CPAP can be improved if all subjects use heated humidification at the beginning of nasal CPAP treatment. However, only patients with considerable upper airway problems may benefit from heated humidification. Several CPAP studies have been performed with and without heated humidification at the beginning of treatment for 1 or 2 nights13,14; it was concluded that heated humidification offered no added benefit concerning further CPAP adherence. Sleep center clinicians should consider pharyngeal and nasal dryness, because these symptoms can be diminished effectively by heated humidification. Although no consensus has been reached regarding the ideal level of air humidification,15,16 nasal CPAP management using heated humidification has become a standard method. However, heated humidification does not prevent all side effects. Furthermore, supplementing with a humidifier adds considerable cost and difficulty to nasal CPAP treatment and complicates the practical process (hygiene, transport).17 Age strongly predicts the necessity for heated humidification in patients with OSA.18 This is not surprising, because the nose is a highly dynamic organ that undergoes considerable functional alterations during aging. Many agedependent changes in the nose have been identified, inCorrespondence: Harun Karamanlı MD Sanatoryum Avaneu 06280 Kecioren – Ankara, Turkey. E-mail: [email protected].