Role of Humidification In CPAP Therapy

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Obstructive sleep apnea (OSA) occurs when the airway temporarily collapses during sleep, preventing or restricting breathing for up to ten seconds or more. Such events can occur several hundred times a night severely disrupting sleep. Untreated OSA can severely affect quality of life, health and mortality. Clinical research shows that it is linked strongly to a range of serious, even life-threatening, chronic diseases such as stroke, heart failure, hypertension, diabetes, obesity and coronary heart disease. CPAP is short for “continuous positive airway pressure” and is widely accepted across the globe as a highly effective, proven and noninvasive way to treat OSA. This treatment involves wearing a mask or nasal pillows system connected to a small portable airflow generator that delivers air at positive pressure. CPAP works by pushing air from the flow generator through the tubing and mask. The air passes through the nose and into the throat, where the slight pressure keeps the upper airway open.

As a result of CPAP treatment, patients may sometimes experience nasal congestion and dryness of the nose and throat. These symptoms can be severe enough to prevent patients from continuing their treatment. Humidification helps to reduce symptoms of dryness and congestion, improving comfort and compliance. Heated humidification can also prevent the increase in nasal resistance that results in mouth breathing and leaks.

What is humidity?

Humidifying the air from a CPAP device involves connecting a specially designed humidifier to a flow generator. According to studies, up to 40% of CPAP users experience nasal congestion and dryness of the nose and throat¹. These symptoms may make the therapy experience extremely uncomfortable or, even worse, prevent patients from continuing treatment. Fortunately, the solution can be as simple and straightforward as adding a humidifier to your system. While humidification may not be necessary for all patients, it can make therapy more comfortable and resolve symptoms such as nasal congestion, mouth breathing, chronic or seasonal allergies, or post-nasal drip. A humidifier adds moisture to the air delivered by a CPAP device, thereby reducing symptoms of dryness and congestion, and improving patient comfort and compliance.

¹Richards et al. Mouth leak with nasal CPAP increases nasal airway resistance. Am J Respir Crit Care Med 1996; 154(1):182-6

The body’s natural humidification process

The human body has its own humidification process that protects the respiratory system. Every time you take a breath, your nose and upper airway add moisture to the air so that it enters your lungs with the necessary humidity. Your nose is responsible for about two-thirds of this process. As the air passes further into your airway, it becomes warmer and more humid. By the time air reaches your lungs, it is at the ideal temperature and humidity. When you exhale, your nose conserves water by recovering about one-third of the moisture present in each exhaled breath. The moisture is then used to assist in the humidification of your next breath.

Environmental factors

Environmental factors can increase demands on your body’s natural humidification process. People with seasonal allergies or sensitivities to the environment suffer an increase in nasal congestion if placed on CPAP therapy. If you travel to extremely dry or cold climates you may experience a sore throat, nasal congestion and irritated sinuses. The lower humidity in these extreme climates puts an extra burden on your body’s normal balance. While some people adjust quickly enough that the humidity change doesn’t affect them, others may experience temporary discomfort or may feel that they cannot adjust to it at all.

CPAP therapy potential challenges

In essence, CPAP therapy creates a new climate for your nose and upper airway because the increased amount of air is more than the person’s body is used to humidifying. The greater the treatment pressure, the more difficult this task becomes. One’s nose may become tender, dry, or create more mucus to protect its sensitive tissues. These nasal symptoms are common in OSA patients. A humidifier can prevent and even reverse these symptoms by humidifying the air before it reaches the nose.

Nasal congestion

Similarly, CPAP therapy can irritate the nose and cause nasal congestion, which may develop over the first week of treatment. Humidification can make therapy more comfortable by relieving nasal congestion.

Deviated Septum

A person with a deviated septum has a nose where one cavity is larger than the other. The small cavity has to work harder to humidify the air the person is breathing. CPAP therapy can further increase the workload of the nose, leading to noncompliance. Humidification helps relieve the workload placed on the nose.
Mouth breathing (or mouth leak)

Breathing through the mouth during sleep can cause a dry mouth. Therefore, patients may be less comfortable. Humidification helps to relieve the dryness associated with mouth breathing. (See the “Mouth leak and the vicious cycle” section for more information)

Exhaustion and discomfort

You may not receive proper levels of pressure and therapy if you suffer from symptoms of poor humidification as mentioned above. These symptoms can ultimately make CPAP therapy an uncomfortable experience. Therefore, you may not be sleeping as efficiently as possible. If you suffer from these symptoms, humidification is an essential component of comfort and complete compliance.

Mouth leak: a vicious cycle

Studies have shown that positive airway pressure can cause nasal resistance, which can lead to mouth breathing (commonly referred to as mouth leak). When air escapes through your mouth, you miss out on the full benefit of the delivered treatment pressure. Mouth leak is a common problem for both experienced CPAP users or for those completely new to therapy. It can be caused by chronic nasal disease and can be worsened by colds, allergies or alcohol consumption. Mouth leak causes high airflow in one direction, preventing the lung’s moist air from passing through your nose, which results in drying of the skin in your nose, nasal congestion, and flu-like symptoms upon awakening. Mouth leak due to mouth breathing is a significant problem that can potentially compromise your CPAP therapy.

Why is mouth breathing a problem?

The mouth leak cycle: Normally as you breathe, the air flowing in and out through the nose is warmed and moistened. Mouth breathing impedes this normal process, resulting in nasal and mouth dryness. Aggravated by the extra flow of air during therapy, this may lead to nasal inflammation and congestion. A vicious cycle begins where increased nasal resistance forces you to keep breathing through your mouth.

Mouth leak during CPAP therapy lessens the effectiveness of treatment, causing a vicious cycle. By breathing through your mouth, you bypass your nose, which is responsible for two-thirds of humidification. This means that you’ve tripled the humidification workload of your upper airway. If you add CPAP therapy on top of that, you may start to experience stronger symptoms. Even if you’re only exhaling through your mouth, you are still losing valuable moisture because you aren’t allowing your nose to recover the moisture your body invested in the air as you inhaled it. In addition to being uncomfortable, increased nasal symptoms can worsen your sleep apnea and lead to increased nasal airway resistance. This in turn leads to further mouth breathing, thus perpetuating the cycle. The result is loss of therapy effectiveness, discomfort and disrupted sleep.³

³Teschler et al. Eur Respir J 1999 Dec; 14(6):1251-1257.

Compliance with CPAP therapy

When beginning CPAP therapy, the proper treatment pressure, a comfortable system, and good education often mean the difference between success and failure for CPAP users. Compliance is often the primary obstacle to CPAP treatment efficacy. Several issues impact compliance, and studies indicate that the lack of resources for homecare providers presents one of the main factors contributing to low levels of compliance ⁴. In the early ‘90s, many researchers agreed that treatment compliance rates were around 46%⁵. Assuming that appropriate support and education are provided, there are two interventions that have been shown to improve compliance. Humidification is one of them. The results of one particular study demonstrated that “heated humidification significantly improves … CPAP daily rate of use and that its need may be predicted.”⁶

⁴Oppenheimer EA. The American experience. iVUN News 1997; 11(2):8-9.
⁵Kribbs NB et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993; 147:887-95.
⁶Rakotonanahary D et al. Heated humidification significantly improves CPAP daily rate of use. Chest 2001; 460-465

Clinical studies

Among the many clinical studies on humidification, the following published articles support for the benefits of heated humidification with CPAP therapy:

Rakotonanahary D, et al. Predictive factors for the need for additional humidification during nasal continuous positive airway pressure therapy. Chest 2001;119(2):460-465.
This study identifies risk factors that may indicate a need for heated humidification: being older than 60 years; using drying medications; presence of chronic mucosa disease and previous uvulopalatopharyngoplasty (UPPP). It also demonstrated that heated humidification significantly improves CPAP daily use, while cold humidification did little.
Martins De Araujo MT, Vieira SB, Vasquez EC, Fleury B. Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000;117(1):142-147 Comment in: Chest 2000;117(3):617-9.
This study found that the inhalation of dry air during CPAP therapy can be significantly lessened by heated humidification, even during mouth leaks, and can be totally prevented by using a full face mask.
Massie CA, Hart RW, Peraliz K, Richards GN. Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure. Chest 1999;116(2):403-408.
This study found that patients who use heated humidification were more compliant with CPAP and suggests that compliance may be realized sooner if patients are started with heated humidity at CPAP initiation.
Richards GN, Cistulli PA, Ungar RG, Berthon-Jones M, Sullivan CE. Mouth leak with nasal continuous positive airway pressure increases nasal airway resistance. Am J Respir Crit Care Med 1996;154(1):182-186.
This study demonstrated that nasal congestion, dry nose and sore throat affect approximately 40% of patients using nasal CPAP. Results also showed that heated humidification greatly decreased patient symptoms while cold passover did little.

Reimbursement

The Centers for Medicare and Medicare Services (CMS) covers either a non-heated (HCPCS code E0561) or heated (HCPCS code E0562) humidifier when ordered by the treating physician for use with a positive airway pressure device. As long as the Medicare beneficiary meets the criteria for a positive airway pressure device, the humidifier is covered as ordered by the treating physician. Typically, most commercial health plans follow these same criteria. Please check with individual health plans to confirm coverage criteria.

References

Teschler et al. Eur Respir J 1999 Dec; 14(6):1251-1257.
Richards GN, Cistulli PA, Ungar RG, Berthon-Jones M, Sullivan CE. Mouth leak with nasal continuous positive airway pressure increases nasal airway resistance. Am J Respir Crit Care Med 1996;154(1):182-186.
Kribbs NB et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993; 147:887-95.
Oppenheimer EA. The American experience. iVUN News 1997; 11(2):8-9.
Rakotonanahary D et al. Heated humidification significantly improves CPAP daily rate of use. Chest 2001; 460-465.
Meyer TJ, Pressman MR, Benditt J, McCool FD, Millman RP, Natarajan R, Hill NS. Air leaking through the mouth during nocturnal nasal ventilation: effect on sleep quality. Sleep 1997;20(7):561-569.
Rakotonanahary D, Pelletier-Fleury N, Gagnadoux F, Fleury B. Predictive factors for the need for additional humidification during nasal continuous positive airway pressure therapy. Chest 2001;119(2):460-465.
Martins De Araujo MT, Vieira SB, Vasquez EC, Fleury B. Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000;117(1):142-147 Comment in: Chest 2000;117(3):617-9.
Massie CA , Hart RW, Peraliz K, Richards GN. Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure. Chest 1999;116(2):403-408.

Cleaning & Maintenance

Just like your CPAP device, proper cleaning and maintenance of your humidifier is essential in increasing the comfort of your therapy and ensuring it is working properly. It is highly recommended that you use distilled water to maximize the life of your humidifier’s water chamber and reduce mineral deposits. (However, it is ok to occasionally use tap water to clean your humidifier.) Do not use bleach, alcohol, chlorine or ammonia-based solutions; moisturizing, antibacterial or glycerin-based soaps; or water softening and unapproved descaling agents.

You should also change the water in the chamber for each use, even if you do not use it all in one night’s time. We suggest washing your humidifier and tubing daily in warm water using a mild detergent. Rinse them thoroughly with clean water and allow them to dry away from direct sunlight. Inspect the water chamber weekly for wear and deterioration. Replace the water chamber right away if any component has cracked, become cloudy or pitted. If you notice white powder or deposits in the water chamber, follow these steps:

Fill the water chamber to the maximum water level and mark with a solution of one part vinegar to ten parts water.
Let the solution soak for 10 minutes.
Discard the solution and rinse the water chamber with clean water.