Sleep technicians and physicians are helping CPAP users with OSA to not only sleep better, but improve their health and quality of life.
The statistics are staggering. More than 20 million Americans may suffer from obstructive sleep apnea (OSA). Other estimates suggest between 2% and 4% of the adult population and close to 20% of the elderly have OSA. It is also estimated that between 1% and 3% of children suffer from sleep-disordered breathing. Furthermore, the loss of productivity, traffic and occupational accidents, and health care costs related to OSA cost tax payers in excess of $60 billion in the United States alone.1,2 For instance, a study performed at the Sleep Disorders Center, St Boniface General Hospital Research Center, University of Manitoba, Winnipeg, indicated that OSA sufferers use health care resources at twice the rate of controls before being diagnosed. This study also determined that OSA patients were 23 times more likely to remain undiagnosed after visiting their physicians than controls.3 However, with increased awareness, proper screening, and effective treatment, the physical, psychological, and social consequences of OSA can be minimized.
OSA is characterized by recurrent airway obstruction that results in oxygen desaturations, carbon dioxide retention, and a disruption of the normal sleep architecture. It is believed that up to 40% of individuals suffering from essential hypertension and one third of patients with heart failure suffer from undiagnosed and untreated OSA.4,5 Compared with the general US population, OSA patients are three times more likely to suffer ischemic heart disease and have four times the incidence of cerebrovascular disease.4 Furthermore, individuals suffering from OSA experience such symptoms as excessive daytime sleepiness, lack of concentration, memory impairment, and psychological disturbances.2 OSA sufferers frequently complain of having a poor quality of life physically, socially, and emotionally.2 In addition, the daytime somnolence associated with OSA can lead to an increased risk for automobile and occupation-related accidents.2 In fact, the National Sleep Foundation reports that at least 100,000 automobile accidents each year are due to sleepy drivers. These accidents result in approximately 71,000 injuries and 1,500 deaths.6 Some states are actually starting to pass laws to prosecute sleepy drivers involved in accidents. Excessive daytime sleepiness is believed to have been a contributing factor in several large-scale industrial accidents such as Chernobyl, Exxon Valdez, and Bhopal.7 The need for accurate diagnosis and effective treatment for OSA patients is growing.
Does CPAP Work?
Continuous positive airway pressure (CPAP) is the gold standard of treatment for OSA. CPAP is a highly effective tool for restoring normal breathing and sleep architecture in subjects with sleep-related upper-airway resistance or obstruction. CPAP was developed in the early 1980s by Colin E. Sullivan, a professor of medicine at the University of Sidney in Australia who provided a noninvasive treatment option for OSA. The goal of CPAP, by acting as an air splint, is to restore normal breathing patterns and maintain normal sleep architecture while maintaining patient comfort. The use of CPAP has been beneficial in the treatment of individuals with OSA, chronic lung disease, congestive heart failure, and neuromuscular disorders, along with a number of neonatal and pediatric applications.
CPAP has been shown to improve the physiological and psychological effects of OSA.2 The Yale Center for Sleep Disorders, Pulmonary and Critical Care Medicine, performed a study evaluating the impact of CPAP on the quality of life in patients with OSA. The results demonstrate that CPAP improves the physical, emotional, and social functioning of OSA sufferers. The 8-week investigation studied 29 OSA patients to determine what effect CPAP would have on their quality of life index. The results of the study showed a marked improvement in vitality, social functioning, and mental health. The investigators believe the results clearly demonstrate that successful CPAP therapy will improve the quality of life for individuals suffering from OSA.2,4
The results of a recently published study indicate that treating OSA with CPAP may substantially reduce the negative effects of OSA on the cardiovascular system.5,7 In fact, heart function actually improved after treatment with CPAP. The study performed by Toronto General Hospital, University Health Network, Mount Sinai Hospital, and the Toronto Rehabilitation Institute consisted of 24 patients with heart failure and OSA; 12 of the participants received treatment with medication alone and 12 with medication and CPAP. The results indicated that those treated with CPAP demonstrated improved heart function, decreased heart size, decreased blood pressure, and decreased heart rate. The heart function was measured using the left ventricular ejection fraction; a 9% increase was noted after 1 month on CPAP. The group treated with medication alone had no improvement. Furthermore, the size of the heart at the end of a beat decreased an average of 3 millimeters after 1 month on CPAP. The group receiving only medication had no change in heart size.5 In another study performed by Becker et al8 therapeutic CPAP was shown to reduce arterial blood pressure by nearly 10 mm Hg after 9 weeks of usage. Such a drop in pressure is predicted to reduce coronary heart disease event risk by 37% and the risk of a cerebrovascular accident by 56%. More research is needed; how-ever, it appears that with therapeutic CPAP settings, some of the negative effects caused by OSA can be reversed.
Successful CPAP treatment for OSA is established only after an accurate titration of pressure has been performed. To determine the therapeutic pressure level, an overnight polysomnogram (PSG) must be performed while the PSG technician adjusts the pressure as needed to eliminate sleep-disordered breathing. A study performed by Drake et al9 indicates that the degree of long-term compliance with CPAP is directly related to the patients experience with CPAP during the titration night. They also suggested that the more severe the disease, the greater the acceptance of CPAP. Therefore, the importance of an accurate initial titration cannot be underestimated. CPAP titrations are generally performed as a separate study, although split-night titrations are sometimes performed for severe OSA. Although it is important for the technician performing the titration to identify and resolve problems and complications quickly, research indicates that split-night CPAP titrations contribute to inadequate pressure settings in up to 49% of patients because insufficient time is spent performing the titration.10 To achieve an optimal pressure level, the technologist must carefully monitor the subjects response in all sleep stages and positions. A successful titration should include the resolution of obvious obstructive events, elimination of snoring and residual upper-airway resistance, and restoration of normal sleep architecture, as evidenced by the electroencephalogram (EEG).
Inexperienced or poorly trained personnel are more likely to miss many of the factors that contribute to poor compliance or failure of therapy. The ability to titrate and troubleshoot CPAP or bilevel support effectively will be found among experienced PSG technicians or respiratory care practitioners who have a thorough understanding of respiratory physiology and anatomy, sleep and respiratory disorders, and sleep and respiratory equipment. Therefore, the use of a simple, yet detailed flowchart may be helpful for the PSG technician when performing CPAP titrations (Figure, page 39). Even when a successful titration is performed, many variables remain that can contribute to a patients inability to tolerate CPAP.
There are three variables that appear to correlate with increased use of CPAP: female gender, increased age, and reduction of daytime sleepiness scores. Although two of the previous factors cannot be changed, daytime sleepiness scores can. The most common factors contributing to poor CPAP tolerance can be divided into three groups: problems with the upper airway and the upper-airway mucosa, poor mask fit or discomfort, and problems with equipment. Furthermore, CPAP compliance often suffers without proper education and follow-up provided by the home medical equipment companies and sleep laboratories.4
Inaccurate pressure settings are often a primary cause of CPAP intolerance. If the pressure is set too low, the individual may suffer from persistent upper-airway resistance and subsequent arousals documented by EEG. 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. Auto-titrating CPAP machines are being employed in an attempt to help individuals intolerant to CPAP due to the pressure setting; however, an auto-titrating CPAP machine cannot eliminate all of the pressure-related problems. The effective nasal-mask pressure may be adversely affected by factors that increase system resistance, such as long tubing or water condensation.11 The pressure can also be affected by dynamic variables such as breathing frequency and tidal volumes.11
Many CPAP users complain of mask discomfort (from leaks, soreness, or skin irritation). These complaints are usually resolved through mask refitting, improved patient education, or the exchange of worn-out equipment for new equipment. Aside from mask comfort, two of the most common problems experienced are nasal congestion and drying of the airway.12,13 According to Richards et al,13 nasal congestion, dry nose, and sore throat affect 40% of individuals using nasal CPAP. It is believed that the unidirectional airflow caused by oral leaks is a primary contributor.12-14 Rakotonanahary et al14 established that the relative humidity of the air delivered by the CPAP device is approximately 20% lower than that of room air. The authors 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.12-14 A study conducted by Martins de Araujo et al12 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.12-14 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 al12 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 chinstrap 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.12 The key to using a full-face mask successfully is determining the proper mask size for the patient and using only headgear designed for that particular mask.
Another common problem that the sleep specialist may encounter is claustrophobia.15,16 Many sleep laboratories have developed protocols that slowly introduce claustrophobic patients to CPAP. A common method is to provide patients with the mask of choice and allow them 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. 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. By eliminating the discomfort caused by the rush of air when the mouth is open, the patient is more comfortable and able to tolerate CPAP.
More than 20 million Americans are believed to suffer from OSA. The related health care costs are staggering; however, sleep technicians and physicians can help the majority of CPAP users not only to sleep better, but improve their health and enjoy an enhanced quality of life. CPAP usage can be increased with successful titrations and accurate, efficient troubleshooting of potential compliance issues. With proper screening, effective treatment, and improved education, the physical, psychological, social, and financial implications of OSA can diminish.
Megan Rauch, RRT, is a staff respiratory care practitioner and sleep specialist, Mott Childrens Hospital and the General Clinical Research Center, University of Michigan Medical Center, Ann Arbor.
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