Sleep Breathing Disorders – A 21st Century Epidemic?
Upon completion of this article, the reader should be able to:
- recognize the various ways that excess weight can lead to an obstructed airway
- understand the interaction of tonsils within the oropharyngeal spaces
- intelligently discuss the impact that alcohol and drugs can have on the ability to sleep and breathe normally
- explain the why the sleep aid market is booming, and how these aids affect breathing during sleep
- understand why the shift in population demographics has created more sleep breathing disorders
- recognize the effects our changing environment is having on the airways and anatomy of the western world
According to the National Sleep Foundation, over 40 million people in the U.S. suffer from sleep disorders. It is believed that as the U.S. population continues to age, sleep disorders will increase in numbers. By 2050, it is estimated that over 100 million people will suffer from some form of sleep disorder. Insomnia is the leading sleep disorder, but sleep apnea is closing fast, as America continues its current slide down that slippery slope of unhealthy living.
"Sleep disordered breathing in its various manifestations is arguably the number one health problem in the U.S., and probably throughout the world" . This was not a quote by a publicity-seeking sensationalist, but by the "Father of Sleep", William C Dement. Dr. Dement has been working in the field of sleep for more than a half century, and he is more worried now than ever before. What has led him to this state of disquietude?
Is this due to more sophisticated methods of recording sleep? Could it be that we are just getting tired of hearing our bed partners snore, and it's time to speak out? Has our awareness grown because of the proliferation of commercials for sleep aids and solutions for restless leg syndrome? This article points to another reason – one that no one likes to think about. America is sick. Breathlessly sick.
A Weighty Matter
It will come as no surprise that obesity is strongly associated with the presence of sleep disordered breathing . Most of us are acutely aware of the progression of this condition, and this author will not belabor the reasons, but a graphical representation will adequately relate this disturbing phenomenon. The data is supplied by the CDC .
Although some states in 2005 had more than 30% of their citizens listed as obese, this is not as much of a concern as is the dramatic trend we are witnessing. Just ten short years prior, not one state had even 20% of their population marked as obese. This escalation is unhealthy on many fronts, but the concern of this paper is to show the effects it is having on breathing Americans.
Characteristics of obesity that lead to a restricted airway include an associated peripharyngeal infiltration of fat, typically observed in the neck circumference. A 17 inch measurement in men and 15 inches in women are generally viewed as predictive of an obstructed airway. Aside from size, the cricomental space is reduced when excess fat is distributed in the neck. To arrive at this measurement, a cricomental line is drawn between the cricoid cartilage and the inner mentum. This line is bisected, and the perpendicular distance to the skin of the neck is the cricomental space.
When this space is less than 1.5 cms, it becomes more predictive of obstructive sleep apnea . In layman's terms, this is referred to as the turkey gobble.
Another anatomical characteristic seen in the obese is an increase in the size of the soft palate and tongue. When enlarged, they can effect a crowded oropharynx. Lastly, in the overweight individual, excessive pull of gravity while in the supine position creates added pressure on the pharynx, leading to compression and a decrease in air flow.
There are many other ways that excessive weight can indirectly exacerbate the breathing problems, but for purposes here, we are listing only the direct physical impact this weight can have on the airway.
Tonsils – Simply Redundant or Hazardous Waste?
Leaving weight behind, so to speak, let's now look at tonsils. We primarily think of the palatine or faucial tonsils, but there are also lingual, pharyngeal (better known as adenoids), and even tubal tonsils. They are all simply redundant tissue that help make up Waldeyer's Ring, where acute and chronic infections reside. All of this lymphoid tissue is part of the immune system, and it traps infectious agents in a defensive manner. However, when overcome with excessive stimulation from these agents, they become ineffective defensive agents. In effect, they are extra baggage.
There is much controversy concerning need for a tonsillectomy, but the downward trend in removal is significant. There were 1.4 million tonsillectomies performed in America in 1959, but this had dropped to 260,000 by 1987. At an average age of 8 for patients undergoing this procedure, the current age of those undergoing a tonsillectomy in 1959 would be 56. The highest incidence of OSA occurs at age 55 , and over the next 25 years, the number of 55-year old Americans who still own their tonsils will increase.
So, why should this concern us? Obstructive tonsillar hypertrophy can create an occluded airway. This can happen without tonsillitis, and at any age. A tonsillectomy is usually indicated in the presence of recurrent tonsillitis, which alternately is defined as four to seven episodes of acute tonsillitis in one year, five episodes for two consecutive years or three episodes per year for 3 consecutive years.
This inflammatory process is symptomatic to parents and pediatricians, but the hypertrophied tonsils which are not inflamed may not get noticed, and the consequence can be an unhealthy plugged airway. This is a 36-year old male patient with obstructive sleep apnea, whose tonsils are a heavy contributor to his condition.
Another concern with tonsils during childhood is the propensity for abnormal growth patterns in the lower face and jaw. Even if the child did not develop a sleep breathing disorder, this abnormal growth pattern would predispose the patient to obstructive sleep apnea as an adult. It has also been shown that craniofacial deformities can improve significantly with surgical treatment of the airway obstruction.
Alcohol and Drug Abuse
Another risk factor for sleep breathing disorders is the consumption of alcohol. It has been demonstrated to increase nasal and pharyngeal resistance in awake patients , so it is reasonable to assume that the sleeping state sees a like correspondence. In fact, Issa and Sullivan demonstrated that the increased tendency to develop obstructive apnea after alcohol is the result of alcohol-induced oropharyngeal muscle hypotonia, while the increased duration of obstructive apnea is the result of alcohol-induced depression of arousal mechanisms.
In younger age groups, the effects may not be noticed, particularly in the individual not predisposed to sleep breathing disorders due to anatomical handicaps. However, as middle age approaches, and the incidence of obstructive sleep apnea increases, alcohol can take a bigger toll.
Based on SAMHSA's 2002 and 2003 National Surveys on Drug Use & Health (NSDUH) , alcohol abuse among adults 55 years and older increased 19% for men and 24% for women from 1995 to 2002. This disturbing trend has serious consequences for those who are already on the cusp of sleep disorders. However, alcohol consumption is the least of their foibles.
Overall drug abuse increased in this age group by 106% for men and 119% for women during the same time frame, and many of these drugs have negative effects on the respiratory complex. The situation reached a point where a new campaign was hatched for adults called "Do the Right Dose".
The dramatic increase has many implications, but for the purpose of this article, we are specifically concerned with breathing. The most abuse came in the form of opiates, which act directly on the respiratory center in the brainstem, where they cause a slowdown in activity. This results in a decrease in breathing rate. Excessive amounts of an opiate, like heroin, can cause the respiratory centers to shut down breathing altogether.
Americans Can't Sleep
According to an annual poll conducted by the National Sleep Foundation, in 2005 (the 2006 poll concentrated on adolescents), 75 percent of Americans experienced sleeping problems ranging from minor to severe and from transient to chronic. That is a 21% increase since 1999, when the NSF first conducted its poll. Largely due to an increase in advertising, the number of Americans turning to prescription sleep aids for help has increased even more dramatically: nearly 60% during that same time frame.
American pharmacists filled about 42 million sleeping pill prescriptions in 2005. In that same year, drug companies spent more than $300 million on ads for prescription sleep aids, which is more than four times as much as they spent in 2004. The result? Americans spent more than $2.5 billion on sleep aids in 2006.
Sedatives used as sleeping aids decrease pharyngeal muscle tone, much like alcohol and opiates, and can exacerbate obstructive sleep apnea. Knowing this, a report called Pipeline and Commercial Perspectives: Insomnia by LeadDiscovery intoned: "The transient insomnia market is severely under served, and presents an ideal niche for manufacturers. If manufacturers can increase the proportion of individuals using prescription hypnotics at least a few nights a month, to the level of those who use them at least a few times a week, usage of prescription hypnotics could increase by 50%."
With financial incentives in the billions of dollars, is it any wonder what will happen to the airways of the 21st century?
Americans Still Can't Sleep
Even with $2.5 billion worth of drugs ingested, America remains sleep-deprived. Before Thomas Edison invented the light bulb, we were getting an average of 10 hours of sleep each night. Now, we are lucky to get 7. In 2002, we averaged 6.9 hours on weeknights when we need it the most and in the most recent poll by the National Sleep Foundation in 2005 , that dropped to 6.8. In the last 40 years, Americans have cut their average sleep time by almost 2 hours.
The Annals of Internal Medicine in 2004 reported a link between sleep deprivation and hormone changes, specifically leptin and ghrelin. Leptin decreases hunger, so people do not feel hungry when leptin levels are high, while ghrelin increases hunger, so people feel hungry when ghrelin levels are high. Researchers found that after limited sleep, leptin levels decreased and ghrelin levels increased, which brought an increase in hunger, especially for foods with high carbohydrate content. Less sleep = more weight.
Researchers at Columbia University in New York City found that people who slept six hours a night were 23 percent more likely to be obese than people who slept between seven and nine hours. Those who slept five hours were 50 percent more likely and those who slept four hours or less were 73 percent more likely to be obese. As mentioned previously, weight gain is the leading indicator for developing an obstructed airway. As America sleeps less in the 21st century, our nightly breathing is headed the wrong way.
It's a House of Cards
Upon reviewing more than 20 studies on snoring prevalence, it became clear that there has been far too much subjectivity in snoring scores over the past 20 years to show credible data which points to the increase we know to exist. Too many studies were weighted toward subsets which were more predictable, such as middle aged males. There were issues with differences in reporting techniques (self-reporting, observer-reporting and objective reporting or polysomnography). To further muddy comparative studies, there were too many varying levels (often, sometimes, very often, never, rarely, occasionally, light, loud, soft, etc.). In fact, the parameters were so muddled that among 15 studies across a seven year span, the prevalence for snoring ranged from 16 to 89%.
With this in mind, and knowing that America is getting heavier and more allergic to her environment, we must assume that snoring is on the rise. As you might imagine, the actual act of snoring can be quite traumatic for the pharyngeal tissues, specifically as the volume and velocity increase. As a result, the uvula can bloat up to 3 times its original size, and the soft palate can elongate toward the posterior pharyngeal wall. This edema is thought to be precipitated by negative pressure trauma. The resultant swelling of these tissues will create a more constricted airway, leading to an increase in snoring volume, and potentially a more apneic individual. In review, as America snores more, America snores even more.
The Graying of America
America is not getting younger. In 1870, the first census of people in the United States who were 65 years of age or older was conducted. Estimates at the time showed that about 1.2 million people, or 3% of the total population, were "old people." The decades since that first census have seen a remarkable transformation—the graying of America.
The years between 1960 and 1980 saw the most dramatic growth of the "grays". During these years the total population of the United States increased 19%, but the population of people age 65 and older increased by about 35%. By 1980 there were about 25 million "grays", and that increase has not diminished in the years since. In 1999 it was estimated that there were nearly 34 million "gray" Americans, or about 12% of the total population, and that by the year 2030 the number of "old" people may reach 20% of the total population.
Old age is associated with an increase in pharyngeal airway collapsibility during sleep , which leads to a restricted airway and concomitant obstructive sleep apnea. The prevalence of snoring and obstructive sleep apnea increase with advancing age, with a prevalence of 70% of elderly males and 56% of elderly females.
Specifically in post-menopausal women, there is a much greater increase in OSA when compared to their pre-menopausal years. One suggestion for this phenomenon is that menopause could cause a different body fat distribution with an increase of fat in upper parts of the body and, consequently, with an increase of neck circumference. The other theory revolves around progesterone. It is thought that this hormone has a powerful protective effect prior to menopause, and that this protection mechanism may reflect the fact that progesterone increases sensitivity to oxygen and CO2 levels in the blood.
Another anatomical observation during maturation of the adult is the length and thickness of the soft palate. It has been shown that the soft palate both lengthens and thickens as one ages , which would lead to an increased prevalence of obstructive sleep apnea in the elderly.
Becoming Allergic to Our Environment
By all accounts, allergic rhinitis is affecting the western world at a record pace each year. The largest study from Britain showed a threefold increase in men and a fourfold increase among women over a 20-year span at the end of the last century. A study from Sweden showed a twofold increase over a 12-year span from 1979 to 1991. Germany showed a homogenous increase across the spectrum during a 5-year study period. Denmark showed the same over 8 years.
Allergic rhinitis is precipitated by both genetic and environmental catalysts. As there have been no genetic upheavals within the last 30 years, it is safe to assume that these dramatic increases are directly related to environmental changes. I won't pretend to analyze the potential for changes in our environment for the better, but can realistically assume that they are not around the corner.
At the 2006 Annual Meeting of the American College of Allergy, Asthma and Immunology, experts presented the newest data. "There is epidemiological evidence that the prevalence of allergic rhinitis is rising worldwide. Reports indicate that it has increased 100 percent in each of the last three decades in developed countries," said Eli O. Meltzer, M.D., co-director, Allergy & Asthma Medical Group & Research Center, and clinical professor of pediatrics at the University of California in San Diego.
All dimensions of sleep are impaired by allergic rhinitis, and breathing is impacted specifically with an increase in snoring and obstructive sleep apnea. Mouth-breathing secondary to relative or complex obstruction of nose or upper airway leads to abnormal bone growth and underdevelopment of craniofacial structures, and therefore, can adversely affect dental occlusion and natural interaction of upper and lower jaws.
Even if children do not develop a breathing disorder from their allergies early in life, continued nasal obstruction will produce habitual mouth breathing. This leads to a high or vaulted palate, which impinges on the nasal turbinates and closes off the neighboring meatus, effectively closing down the needed nasal airway in adulthood. One study also showed retrognathic mandibles in children who had occluded nasal airways.
Allergic disorders may affect more than 1.4 billion people worldwide, and one study showed that 42% of children had physician-diagnosed allergic rhinitis by 6 years of age. When you consider that these numbers are rising at a significant rate, it's easy to see that sleep breathing disorders will continue to be a significant health concern among every age group.
Not quite. As the air-compromised among us proliferate, it is too new in the evolutionary process to weed out the anatomical characteristics that occlude the airway so efficiently. As previously noted, the pathogenesis of obstructive sleep apnea is related to a reduction in the size of the upper airway. This reduction is secondary to enlargement of the parapharyngeal fat pads, compromises in the craniofacial architecture (smaller mandible, vaulted palate, enlarged turbinates, etc.), redundant pharyngeal tissue (tonsils and adenoids) and enlargement (transient or permanent) of the accompanying soft tissue structures (tongue, lateral pharyngeal walls).
Genetics are thought to be a big player in the determination of these anatomic risk factors for sleep apnea. With successful mapping of the human genome, recent evidence is accumulating about the genetic loci for these structural risk factors that predispose to the development of obstructive sleep apnea. However, this knowledge is rather useless for our purposes here. If we continue the trends discussed above, we will only pass along the anatomical and environmental troubles to our progeny. Maybe it's not an epidemic, but it's most certainly a genetic conundrum we need to decode.
Dement, William C, Koenigsberg, Robert; Impediments to Access to Care; Sleep Review, September, 2006
Young, T., Palta, M., Dempsey, J. et al, The Occurrence of Sleep-Disordered Breathing Among Middle Aged Adults; NEJM Volume 328:1230-1235; April 29, 1993; Number 17
Overweight and Obesity; U.S. Obesity Trends 1985-2005
Advanced Practice in Acute & Critical Care. Acute Care of the Aging Client. 13(1):103-113, February 2002 Obstructive Sleep Apnea: Recognition and Management Considerations for the Aged Patient
2002 publication of New England Journal of Medicine; 2003 study by American Thoracic Society
APMIS. 2004 Apr-May;112(4-5):248-56Macroscopic oropharyngeal signs indicating impaired defensive function of palatine tonsils in adults suffering from recurrent tonsillitis.
Drake, A. Tonsillectomy; EMedicine June 15, 2005
Bixler, E., Vgontzas, A., Ten Have, T., et al; Effects of age on sleep apnea in men; Am. J. Respir. Crit. Care Med., Volume 157, Number 1, January 1998, 144-148
Acta Oto-Laryngologica, Volume 118, Issue 4 1998 , pages 581 - 587Children with Nocturnal Upper Airway Obstruction: Postoperative Orthodontic and Respiratory Improvement
Robinson RW, White DP, Zwillich CW. Moderate alcohol ingestion increases upper airway resistance in normal subjects. Am Rev RespirDis 1985;132:1238–1241.
J Neurol Neurosurg Psychiatry. 1982 Apr;45(4):353-9
Results from the 2005 National Survey on Drug Use and Health; Department of health and Human Services; Substance Abuse and Mental Health Services Administration - Office of Applied Studies
2005 "Sleep in America" poll by the National Sleep Foundation
Lyle D. Victor, M.D. Am Fam Physician 1999;60:2279-86
2005 "Sleep in America" poll by the National Sleep Foundation
Annals of Internal Medicine 7 December 2004 | Volume 141 Issue 11 | Page I-52
Anesth Prog. 2006 Spring;53(1):13-6 Uvular edema secondary to snoring under deep sedation.
Chest. 2007; 131:1702-1709
Paul R. Carney, Richard B. Berry – Clinical Sleep Disorders – 2005
Diabetes Nutr Metab. 2004 Oct;17(5):296-303.
European Journal of Orthodontics – Cephalometric changes in adult pharyngeal morphology21 (1999) 357-362
BMJ. 2000 July 8; 321(7253): 88–92. Intergenerational 20 year trends in the prevalence of asthma and hay fever in adults: the Midspan family study surveys of parents and offspring
Clin Exp Allergy. 1995 Sep;25(9):815-9. Increase of asthma, allergic rhinitis and eczema in Swedish schoolchildren between 1979 and 1991.
Allergy, Volume 58, Number 7, July 2003 , pp. 572-579(8) Are asthma and allergies in children and adolescents increasing? Results from ISAAC phase I and phase III surveys in Münster, Germany
Allergy. 54(11):1194-1198, November 1999. Increasing prevalence of allergic rhinitis symptoms in an adult Danish population
Arch Intern Med. 2006;166:1744-1748. Allergic Rhinitis and Its Consequences on Quality of Sleep
Proffit WR, Field HW. Contemporary-orthodontics. 3rd-ed. Mosby; 2000
The European Journal of Orthodontics 1985 7(2):83-92; doi:10.1093/ejo/7.2.83
Pediatrics. 1994 Dec;94(6 Pt 1):895-901Epidemiology of physician-diagnosed allergic rhinitis in childhood.
Respir Physiol Neurobiol. 2005 Jul 28;147(2-3):289-98 Genetic determinants of upper airway structures that predispose to obstructive sleep apnea.