Central Sleep Apnea DSM-5 327.21 (G47.31)
DSM-5 Category: Sleep-Wake Disorders
Introduction
A sleep-related disorder in which blood oxygen is reduced due to the interruption of the normal breathing cycle during sleep, central sleep apnea can be divided into three main subtypes, detailed by the DSM-5. These subtypes are, namely, idiopathic central sleep apnea, Cheyne-Stokes breathing (DSM-5 code: 786.04), and central sleep apnea that is comorbid with the use of opioids (DSM-5 code: 780.57). Each of these disorders is characterized by the presence of apneas – or the interruption of breathing cycles while asleep – which can increase the risk of cardiovascular diseases. Idiopathic central sleep apnea is present if there are regular occurrences of apneas and hypopneas while the individual is asleep, and if there is no blockage of the respiratory tract. A common feature of Cheyne-Stokes breathing is the interruption of sleep, along with episodes of rapid breathing that culminate in an apnea. Central sleep apnea may stem from the use of opioids (such as those belonging to the category of pain medication), and it may also occur as a consequence of traveling to regions with relatively high altitudes (Javaheri and Dempsey, 2013).
Two main criteria are employed in the diagnosis of central sleep apnea (American Psychiatric Association, 2013). Firstly, the patient must have more than four central sleep apneas for every hour of sleep. This can be determined through polysomnographs, which are used to detect and diagnose a variety of sleep-related disorders. The second criterion is that the apneas are not caused by some other sleep disorder.
Symptoms of Central Sleep Apnea
There are numerous symptoms that suggest the presence of central sleep apnea. For instance, intermittent cessations of breathing during sleep are indicative of central sleep apnea. The National Institute of Health, as well as the DSM-5, outlines several other symptoms of central sleep apnea. Individuals who experience excessive daytime sleepiness and fatigue may suffer from central sleep apneas. Morning headaches are an additional sign of central sleep apnea, as are difficulties in swallowing, a general feeling of lethargy, and problems in memory.
Detecting Central Sleep Apnea
Several techniques that test for the existence of central sleep apnea have been developed. Magnetic imaging resonance (MRI), for example, can be used to detect morphological features of the brain stem that correspond with central sleep apnea (Duning et al., 2013). Echocardiograms may also be employed to identify and monitor central sleep apnea in a patient. Recently, a novel technology has been proposed to more effectively monitor the condition of sleep apnea patients (Oh et al., 2011), thus bypassing the need for polysomnographs, which are, as the authors state, “expensive, inconvenient, time consuming, and labor intensive” (Oh et al., 2011). Their new system is based on wireless signaling among a monitoring unit, a receiver, and a transmitter. In this way, vital signs associated with sleep apneas can be analyzed and a diagnosis of central sleep apnea can be made.
Comorbidity
There is an increased risk of developing particular complications if an individual has been diagnosed with central sleep apnea. Heart complications are perhaps the most common comorbid afflictions of central sleep apnea, and Muñoz et al. (2012) have shown that there is a higher risk of stroke in patients with central sleep apnea. Bakker et al. (2012) found a statistically significant correlation between mortality rates from congestive heart failure and central sleep apnea. Additionally, congestive heart failure was more common in patients with sleep apneas. In particular, a total of 68% of individuals with congestive heart failure also have sleep apneas. Of this percentage of patients, 15% had central sleep apnea and 53% had obstructive sleep apnea.
Causes
Understanding the physiological basis of central sleep apnea is critical to the development of effective treatment methods of the disorder. The brainstem is known to be a key player in the origin of central sleep apnea (Duning et al., 2013), which is consistent with current knowledge of the anatomical components of the brainstem. The brainstem houses the medulla oblongata, the part of the brainstem responsible for regulation of breathing and heart rate. It is to be expected, then, that faulty functioning of the medulla oblongata would lead to symptoms similar to those seen in central sleep apnea.
There is, moreover, a possible genomic basis for central sleep apnea. Identifying the genes involved in inducing central sleep apnea is difficult since gene knockout experiments are not performed on humans. Nonetheless, knockout experiments can be conducted on model organisms like mice, and in this way the genomic alterations behind central sleep apnea have been explored (see Davis and O’Donnell, 2013). Among the genetic and molecular factors that give rise to central sleep apnea is monoamine serotonin. Heightened levels of monoamine serotonin correspond to large numbers of apneas during sleep, as highlighted by David and O’Donnell (2013), and gene knockouts in mice that targeted the enzyme regulator of monoamine serotonin further demonstrated this.
Treatment for Central Sleep Apnea
Unlike many disorders, central sleep apnea is usually not treated by the administration of pharmacological products. Instead, technological devices are employed to at least minimize the effects of central sleep apnea. One of the primary technologies utilized in the treatment of central sleep apnea is the continuous positive airway pressure (CPAP) system (Troitino et al., 2013), which uses a moderate degree of air pressure to ensure that the patient’s airways always remain open. It is not a foolproof method, however, and Montesi et al. (2013) point out that air leakage during titration of CPAP can generate central sleep apnea symptoms.
Research by Chowdhuri et al. (2012) suggests a technique for treating central sleep apnea does not rely wholly on CPAP. These authors investigated the effectiveness of CPAP, supplemental oxygen, and bilevel positive airway pressure (BPAP). Their findings indicate that the most optimal strategy for treating central sleep apnea was a combination of CPAP and positive airway pressure oxygen gas: of 162 patients who underwent treatment through the various methods mentioned above, CPAP coupled with oxygen was capable of removing central sleep apnea symptoms from 71% of the patients. This protocol is therefore a potent method for countering the effects of central sleep apnea.
References
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.
Bakker, J.P., Campbell, A.J., Neill, A.M. (2012). Increased mortality risk in congestive heart failure patients with comorbid sleep apnoea: 10-year follow up. International Medicine Journal, 42(11), 1264-1268.
Chowdhuri, S., Ghabsha, A., Sinha, P., Kadri, M., Narula, S., Badr, M.S. (2012). Treatment of central sleep apnea in U.S. veterans. Journal of Clinical Sleep Medicine, 8(5), 555-563.
Davis, E.M., O'Donnell, C.P. (2013). Rodent models of sleep apnea. Respiratory Physiology and Neurobiology, 188(3), 355-361.
Duning, T., Deppe, M., Brand, E., Stypmann, J., Becht, C., Heidbreder, A., Young, P. (2013). Brainstem involvement as a cause of central sleep apnea: pattern of microstructural cerebral damage in patients with cerebral microangiopathy. PLoS One, 8(4), doi: 10.1371/journal.pone.0060304.
Javaheri, S., Dempsey, J.A. (2013). Central sleep apnea. Comprehensive Physiology, 3(1), 141-163.
Montesi, S.B., Bakker, J.P., Macdonald, M., Hueser, L., Pittman, S., White, D.P., Malhotra, A. (2013). Air leak during CPAP titration as a risk factor for central apnea. Journal of Clinical Sleep Medicine, 9(11), 1187-1191.
Muñoz, R., Durán-Cantolla, J., Martinez-Vila, E., Gállego, J., Rubio, R., Aizpuru, F., De La Torre, G., Barbé, F. (2012). Central sleep apnea is associated with increased risk of ischemic stroke in the elderly. Acta Neurologica Scandinavica, 126(3), 183-188.
Oh, S., Varadan, V., Kwon, H. (2011). Ubiquitous Health Monitoring System for Diagnosis of Sleep Apnea With Zigbee Network and Wireless LAN. Journal of Nanotechnology in Engineering and Medicine, 2, doi:10.1115/1.4003927.
Troitino, A., Labedi, N., Kufel, T., El-Solh, A.A. (2013). Positive airway pressure therapy in patients with opioid-related central sleep apnea. Sleep and Breathing, Epub ahead of print.
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