Although new treatment options for obstructive sleep apnea continue to be explored, CPAP remains the best treatment to date. Compliance rates can be improved by learning to overcome factors that contribute to poor tolerance.

Obstructive sleep apnea (OSA) in adults is characterized by recurrent airway obstruction that results in oxygen desaturations, carbon dioxide retention, and a disruption of the normal sleep pattern. Those with OSA are at an increased risk for such symptoms as excessive daytime tiredness, lack of concentration, memory impairment, and psychological disturbances.¹ Individuals with OSA complain of having a poor quality of life physically, socially, and emotionally.¹ Furthermore, the symptoms of OSA can lead to an increased risk of automobile and occupation-related accidents.² In addition, increased cardiovascular and cerebrovascular morbidity and mortality1 appear to be associated with OSA. Current estimates indicate that 2% to 20% of the population may experience sleep-related breathing disorders, including up to 60% of the elderly population.^3-5 The demand for proper diagnosis and treatment is soaring in response to the large number of potential OSA patients.

As the field of sleep medicine expands, sleep specialists continue to explore new treatment options for OSA, such as positional training, avoidance of alcohol and sedative drugs, mandibular advancement devices, and upper-airway surgery.¹ CPAP, however, remains the best option for the majority of OSA patients.¹ CPAP was developed in the early 1980s to provide a noninvasive treatment option for OSA. The goal of CPAP is to restore normal breathing patterns and maintain normal sleep while maintaining patient comfort. There remain, however, a number of factors that limit compliance with CPAP. In fact, a study performed by Pepin et al⁶ indicated compliance rates in Europe of 65% to 80%, compared with an even lower effective compliance rate of approximately 46% in the United States. Pepin et al believe that the difference in effective compliance rates between Europe and the United States is due to variations in prescription and technical follow-up care. There are three variables that appear to correlate with increased use of CPAP: female gender, increased age, and reduction of daytime sleepiness scores. The factors limiting effective compliance with CPAP can be divided into three groups: problems with the upper airway and/or the upper-airway mucosa, with mask fit or discomfort, and with equipment. Two other common problems contributing to poor CPAP compliance are poorly trained or inexperienced staff and lack of proper education and training of patients. Compliance rates for CPAP can be improved substantially by overcoming the factors that contribute to poor CPAP tolerance.⁶

When used properly, CPAP is a highly effective tool for restoring normal breathing and sleep patterns in subjects with sleep-related upper-airway resistance or obstruction. The use of CPAP has been beneficial in the treatment of individuals with OSA, chronic lung disease, congestive heart failure, and a number of neuromuscular disorders. Successful CPAP treatment for OSA is established only after an accurate titration of pressure has been performed. Overnight polysomnography (PSG) must be performed while the sleep technician (polysomnographer) adjusts the pressure as needed to eliminate sleep-disordered breathing. CPAP titrations are generally performed as a separate study, although split-night titrations are sometimes performed for severe OSA. Research indicates that split-night CPAP titrations contribute to inadequate pressure settings in up to 49% of patients because insufficient time is spent in titration.⁷ To achieve an optimal pressure level, the technologist must carefully monitor the subject’s response in all sleep stages and positions. A successful titration should include the resolution of obvious obstructive events, the elimination of snoring and residual upper-airway resistance, and the restoration of normal sleep, as evidenced by the electroencephalogram (EEG).⁷

Performing Titration
At the beginning of titration, pressure is kept at a minimum level. Frequently, a ramp feature is used to allow individuals to become accustomed to the pressure slowly. Generally, CPAP is started at 3 to 5 cm H2O. Once sleep has been achieved, the pressure is titrated rapidly until apneas are eliminated and sleep is maintained. After the apneas are eliminated, the pressure should be increased 1 cm H2O at intervals of at least 15 minutes to eliminate residual upper-airway resistance, snoring, arousals, and oxygen desaturations. It is not uncommon for a titration to appear successful, only to have events reappear suddenly. It is important to remember that flow, respiratory tracings, and oximetry alone are not always reliable indicators of obstructed breathing. It is common to reach a pressure level that eliminates respiratory events, only to have events appear again once the patient changes position. In a study of 60 OSA patients conducted by Oksenberg et al,⁷ it was determined that the optimal CPAP pressure required was significantly higher in the supine position than in the lateral position. The pressure level required to eliminate sleep-disordered breathing while the patient was supine was higher without regard for the presence of obesity or rapid–eye-movement (REM) sleep. These authors also determined that the optimal pressure setting was reached once the patient slept supine during REM sleep. Therefore, they suggested that no study should be considered complete without the patient having slept in the supine position during REM sleep.

When CPAP is not tolerated or fails, bi-level positive pressure is often employed. Bi-level support can be an effective therapy for the chronic patient, and is increasingly being used successfully in the acute care setting as well. Bi-level positive-pressure ventilation uses two pressure settings: the expiratory positive airway pressure (EPAP) and higher inspiratory positive airway pressure (IPAP). Generally, the EPAP is titrated along with the IPAP until obstructive apneas have been eliminated. The IPAP is then titrated to eliminate residual upper-airway resistance or snoring. For those suffering from alveolar hypoventilation or chronic lung disorders, increasing the IPAP without increasing the EPAP will increase the tidal volume, improving ventilation and oxygenation in some patients. Bi-level devices are often preferred for individuals with alveolar hypoventilation and chronic lung disorders. A successful pressure titration is essential to eliminating sleep-disordered breathing while maintaining patient comfort.

Making CPAP Work
It is important for the technician performing the titration to identify and resolve problems or complications quickly. For instance, the effective nasal-mask pressure may be adversely affected by factors that increase system resistance, such as long tubing or water condensation.⁸ The pressure also can be affected by dynamic variables such as breathing frequency and tidal volumes.⁸ If the pressure is set too low, the individual may suffer from persistent upper-airway resistance and subsequent EEG arousals. More significantly, subtherapeutic pressures may increase the potential for post-treatment hypoventilation with subsequent carbon dioxide retention and hypoxemia. Conversely, if CPAP pressures are set too high, the subject may experience discomfort resulting in fragmented sleep, frequent awakenings, or oral leaks. Some patients who use high-pressure levels may experience central apneas. Even when a successful titration is performed, many variables remain that can contribute to a patient’s inability to tolerate CPAP.

A common complaint of CPAP users is mask discomfort (from leaks, soreness, or skin irritation). Fortunately, CPAP suppliers have developed more delivery options for CPAP patients. These complaints are usually resolved through mask refitting, improved patient education, or the exchange of worn-out equipment for new equipment. A common practice used to improve compliance and comfort is to fit patients properly and then allow them to sit or lie down while holding their masks in place. This allows them to become accustomed to the mask and pressure while still being able to remove the mask quickly. It also permits them to try different mask styles.

Even with a comfortable mask that fits well and has accurate pressure levels, the CPAP patient may experience problems that could reduce compliance or lead to failure of the therapy. Two of the most common problems experienced are nasal congestion and drying of the airway.^9,10 According to Richards et al,¹⁰ nasal congestion, dry nose, and sore throat affect 40% of individuals using nasal CPAP.¹⁰ It is believed that the unidirectional airflow caused by oral leaks is a primary contributor.^9-11 Rakotonanahary et al¹¹ established that the relative humidity of the air delivered by the CPAP device is approximately 20% lower than that of room air. They noted that drying of the nasal mucosa has been shown to induce the release of vasoactive leukotrienes, leading to increased nasal resistance. The increase in nasal resistance is one of the primary contributors to oral leaks, which lead to the dry-mouth effect from which many patients suffer.^9-11 A study conducted by Martins de Araujo et al⁹ demonstrated that the use of heated humidification increased the relative humidity of inspired air, thus limiting irritation to the nasal mucosa and decreasing nasal airway resistance. A cold pass-over humidifier did not appear to be a significant factor in improving compliance.^9-11 The heated humidifier was found to be effective in reducing or eliminating some of the side effects of CPAP. If heated humidity alone is unable to reduce nasal irritation sufficiently, then a full-face mask should be tried. Martins de Araujo et al⁹ demonstrated that the use of a full-face mask prevented changes in relative humidity that could lead to water loss in the airway whether the mouth was open or closed. A chin strap may be helpful for some individuals, but full-face masks were shown to be the best choice for reducing the problems associated with oral leaks and nasal pathology.⁹ The key to using a full-face mask successfully is determining the proper mask size for the patient. Only headgear designed for that particular mask should be used.

Another common problem that the sleep specialist may encounter is claustrophobia.^12,13 Claustrophobic patients commonly complain about confinement and the inability to breathe through the mouth (which enhances the feeling of confinement). It has been our experience in the General Clinical Research Center at The University of Michigan Medical Center, Ann Arbor, that some patients who complain of claustrophobia do well with full-face masks. A full-face mask is often successful in reducing the feeling of confinement by allowing the individual to breathe orally and eliminating the discomfort caused by the rush of air when the mouth is open. Many sleep laboratories have developed protocols that slowly introduce claustrophobic patients to CPAP. A common method is to provide the patient with the mask of choice and allow him or her to take it home. While at home, the patient gradually increases the amount of time spent wearing the mask (without CPAP) each day, with the goal being comfort with the mask by the time that the patient returns for a CPAP titration.

The Human Factor
Inexperienced or poorly trained staff may contribute to an individual’s lack of CPAP compliance.¹⁴ It is common for some sleep centers to hire personnel with little or no medical background to perform PSGs and CPAP titrations. Even individuals with some medical background may lack the skills needed to perform CPAP/bi-level titrations. The ability to titrate and troubleshoot CPAP or bi-level support effectively will be found among experienced technicians or RCPs who have a thorough understanding of respiratory physiology and anatomy, sleep and respiratory disorders, and sleep or respiratory equipment. There are substantial differences between performing a standard sleep study and performing CPAP/bi-level titrations. The failure of HME companies to educate and follow the patient properly may also contribute to poor compliance rates.¹⁴ In fact, many HME companies employ nonmedical personnel to set up equipment and educate their clients. The follow-up care and reinforcement provided are important factors to increase compliance. For instance, simple telephone reinforcement is somewhat effective,⁶ and Chervin et al¹⁵ determined that written information was slightly more beneficial. Another study¹⁶ suggested that successive CPAP studies and home training of the patient and spouse increased CPAP use from 4.8 to 6.2 hours per night. Clearly, hands-on training and education are important to the success of CPAP. Unfortunately, managed care or poor reimbursement may limit the ability of a sleep laboratory or HME company to provide proper education and follow-up care for CPAP clients. In an attempt to provide adequate information and follow-up care, some sleep laboratories and home care companies sponsor support groups or CPAP clinics that help educate the general population about OSA and that may even improve CPAP compliance.

With the proper training and a strong knowledge of the problems and complications associated with OSA and CPAP, the sleep technician or physician can help the majority of CPAP users not only to sleep better, but to enjoy an enhanced quality of life. The successful treatment of sleep-disordered breathing using CPAP can substantially reduce symptoms of daytime sleepiness that could lead to an increased risk of automobile and occupational accidents. CPAP can reduce the risk of cardiovascular and cerebrovascular health problems related to OSA as well. With the development of new delivery devices, heated humidity, more comfortable masks, and improved education and training for the technician and patient, CPAP compliance can improve.

Megan Rauch, RRT, is a staff RCP and sleep specialist, Mott Children’s Hospital and the General Clinical Research Center, University of Michigan Medical Center, Ann Arbor, and sleep technician, Michigan Institute of Sleep Medicine, Novi.

References
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