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Sleep Apnea In The Elderly BY AHMAD YOUNES PROFESSOR OF THORACIC MEDICINE Mansoura Faculty of Medicine. Poor Sleep Behaviors. Primary Sleep Disorders. Medical Illness & Medications. Psychiatric & Neurologic. Circadian Changes. Causes of Disturbed Sleep in Aging. Sleep Problem.
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Sleep Apnea In The Elderly BYAHMAD YOUNESPROFESSOR OF THORACIC MEDICINE Mansoura Faculty of Medicine
Poor Sleep Behaviors Primary Sleep Disorders Medical Illness & Medications Psychiatric & Neurologic Circadian Changes Causes of Disturbed Sleep in Aging Sleep Problem
Prevalence of Primary Sleep Disorders ConditionAll AdultsElderly • Insomnia 10-20% 40-50% • Sleep Apnea 1%-25% 24%-40% • Periodic Limb Movements 2-5% 30%-45% • Restless Leg Syndrome 2%-15% 12%-30% • REM Sleep Behavior 0.5% 0.5%-2%
Definition of sleep apnea • Sleep disordered breathing includes 1- Obstructive sleep apnea syndrome (OSAS) 2-Central sleep apnea syndrome (CSAS) and 3- Sleep hypoventilation syndrome . • Obstructive sleep apnea is defined as 5 or more obstructive respiratory events per hour of sleep accompanied by nocturnal or daytime symptoms, or by 15 or more obstructive respiratory events per hour of sleep without accompanying symptoms. • Central sleep apnea is defined as 5 or more central respiratory events per hour of sleep.
Respiratory events • Respiratory events may be apneas (cessation of airflow for at least 10 seconds) or hypopneas (at least 30% or 50% reduction of airflow lasting 10 seconds, associated with a drop in oxyhemoglobin saturation of 4%, 3 % or arousal respectively ). Respiratory effort related arousal exist when there is a sequence of breaths that lasts at least 10 seconds, is characterized by increasing respiratory effort and leads to an arousal from sleep but does not meet the criteria of an apnea or hypopnea • The apnea–hypopnea index (AHI) is the number of apneas and hypopneas per hour of sleep. • The respiratory disturbance index (RDI) refers to the number of apneas, hypopneas, and respiratory effort-related arousals per hour of sleep. • The severity of sleep apnea is generally classified by the AHI. AHI of < 5 is considered to be normal, AHI 5–15 is mild sleep apnea, AHI 16–30 is moderate sleep apnea, and AHI >30 is severe sleep apnea
Significance of involuntary sleepiness • Daytime sleepiness can be assessed subjectively by questionnaires such as the Epworth Sleepiness Scale (ESS) and objectively by investigation in the sleep laboratory such as the Multiple Sleep Latency Test (MSLT). • Elderly patients with sleep apnea report more sleepiness than elderly subjects without sleep apnea and they report a similar degree of sleepiness as young apneic subjects . • A complaint of daytime sleepiness in the elderly should not be attributed to normal aging, and should prompt further evaluation for an underlying cause including sleep apnea.
Prevalence of sleep apnea • Although the prevalence of OSA is over 4%, only 1.6% had such a diagnosis by their physician, and only 0.6% were actually treated for OSA, indicating under-diagnosis and under-recognition of this important disorder . • In the pediatric population, OSA is estimated to occur in 1–3% of children with a peak age of 2–5 years • The prevalence of OSA is higher in certain groups, such as those with male gender, genetic factors, hormonal disorders (e.g. hypothyroidism), acromegaly, polycystic ovary syndrome, and specific diseases such as renal failure or diabetes. • The prevalence of OSA among obese individuals has been reported to exceed 30% and may reach as high as 50–98% in the morbidly obese population . • The overall prevalence of OSA in the elderly is estimated at roughly 30%
Prevalence of sleep apnea • In a community-based study of subjects aged 30–60 years, 24% of men and 9% of women had sleep apnea, defined as an AHI ≥5; • 2% of women and 4% of men had sleep apnea syndrome, defined as an AHI ≥5 accompanied by complaints of daytime sleepiness. • Elderly have sleep apnea prevalence ranging from 18% to 62%. • The prevalence of sleep apnea increased with advancing age . • The apparent increased prevalence of sleep apnea in the elderly may be largely due to an increased prevalence of central sleep apnea associated with normal aging ,
Prevalence of sleep apnea • The severity of associated hypoxemia decreased with advancing age. • Sleep apnea syndrome (defined as an AHI ≥10 accompanied by daytime symptoms) was highest in the middle-aged group. • This suggests that although sleep apnea is more prevalent in the elderly, it is less likely to be symptomatic and to have physiological consequences such as significant hypoxemia. • This raises the issue of its clinical relevance and whether the criteria for diagnosis of sleep apnea should be different in the elderly than in middle-aged adults.
Pathogenesis of sleep apnea • The underlying mechanisms that promote the development of sleep apnea in the elderly can be classified into: (1) Replication of the patho-physiology of sleep apnea in middle-aged adults (2) Physiological changes that are uniquely associated with aging; and (3) Consequences of chronic medical disorders and/or medications.
Pathophysiology of sleep apnea in middle-aged adults • The predominant cause of obstructive sleep apnea in middle-aged adults is obesity, either through its effects on the pharynx and to a lesser extent on lung volume. • In the Sleep Heart Health Study the strength of the association between sleep apnea and body weight decreased as age increased. • Male gender is a strong risk factor for sleep apnea, with males having approximately twice the prevalence of sleep apnea as females. This increased prevalence in males is still seen in the elderly , despite the fact that after menopause the prevalence of sleep apnea increases significantly in women.
Physiological changes that are unique to aging • The physiological consequences of obstructive apnea are a rise in PaCO2, a fall in PaO2, and an increased ventilatory effort against an occluded airway. • Ultimately, transient arousals from sleep generally occur, which re-establish airway patency and ventilation. • The individual subsequently returns to sleep and the cycle repeats throughout the night. • The principal abnormality in the individual with OSA is an anatomically small pharyngeal airway. • During wakefulness, the individual compensates for the deficient anatomy via reflexive increases in the activity of upper airway muscles that maintain airway patency. • With sleep onset, these protective compensatory reflexes are lost and airway collapse occurs. • Both pharyngeal anatomy and physiology may change with age, resulting in the observed age-related increases in the prevalence of OSA.
Physiological changes that are unique to aging • There are conflicting data on how aging affects the upper airway, the diameter of which has been reported to be larger or smaller in older adults compared to control subjects. • Advancing age is associated with increased pharyngeal collapsibility and increased pharyngeal resistance during sleep , both of which may predispose to the pathogenesis of obstructive sleep apnea and contribute to an increased prevalence of obstructive sleep apnea in the elderly.
Physiological changes that are unique to aging • There are a number of underlying pathophysiological variables (anatomy ,upper airway muscle function, and central ventilatory instability) that may be important in determining apnea status. • In some patients, they may have primarily an anatomical problem, whereas other OSA patients may have primarily a problem with upper airway muscle dysfunction. • Variety of sleep apnea phenotypes exist whereby a particular variable (or group of variables) increases the risk of (or protects from) the development of OSA. • These phenotypic clusters are potentially important since therapies targeting the underlying pathogenesis of the condition are likely to be different for each of these subgroups
UAW anatomy • The upper airway requires stiffness of the soft tissue walls around it and activity of the dilator muscles to maintain patency. • Any reduction in UAW cross sectional area, change in its length, muscle activity, or a combination of these variables, may lead to vulnerability of the UAW to collapse. • Many of these characteristics may be affected by aging. • Upper airway dilator muscle and increased lung volume tend to maintain pharyngeal patency. • A small pharyngeal airway in apnea patients is found compared to controls, with the smallest airway luminal size generally occurring at the level of the velopharynx in both patients and controls .
UAW anatomy • Through upper airway receptormechanisms during wakefulness, there is an increase in the activity of the pharyngeal dilator muscles. However, during sleep, these protective mechanisms fail leading to a fall in activity of the pharyngeal dilator muscles and an increased propensity for loss of upper airway patency. • Aging may compromise upper airway anatomy, and/or neural control of upper airway muscles either through the CNS or through peripheral upper airway receptor mechanisms. • Finally increased end expiratory lung volume can promote upper airway patency, although this mechanism could also be compromised with aging.
UAW anatomy • Sleep apnea patients have increased thickness of the lateral pharyngeal walls . • This finding is helpful in explaining the reduced lateral diameter of the airway lumen in OSA patients as compared to controls. • Using acoustic reflection in 60 men and 54 women with an age range of 16–74 years. All upper airway dimensions, except at the oropharyngeal junction, decreased with increasing age in both healthy men and women. • Another researcher ,Older patients (>63 years) had larger upper airways at all pharyngeal levels than the youngest group of patients (<52 years), using a CT assessment of airway size. • The studies assessing the effects of age on airway anatomy are too sparse and disparate to draw firm conclusions.
UAW length • Since cross-sectional UAW is generally greater in men than women, intrinsic pharyngeal size is an unlikely explanation for the male predisposition to pharyngeal collapse. • Men had a significantly longer UAW than women, independent of body size, so major independent effect of pharyngeal airway length on upper airway collapsibility. • As non-rigid tubes become longer they are increasingly prone to collapse (assuming similar tethering); So airway length is a potentially important mechanism responsible for the increased UAW collapsibility. • A significant positive correlation between RDI and UAW length, which persisted when UAW length was normalized to body height .
UAW length • Airway length may also partially explain the age-related change in the gender predisposition of OSA in children. While in pre-pubertal children the prevalence of OSA is similar between genders, there is a known male predominance in the post-pubertal population and in adults. • Pre-pubertal children UAW length was similar between boys and girls, and even shorter in boys when normalized to body height • The pharyngeal airway became significantly longer in post-pubertal males compared to females (both absolute length and length normalized to body height)
UAW muscle function • Airway patency depends on both UAW anatomy and function, • Manydiseases such as muscular dystrophy and myopathy result in increased risk of OSA, probably secondary to the loss of protecting effect of the UAW dilators. • Three groups of muscles have been investigated in the context of the pathogenesis of OSA: (1) the muscles influencing hyoid bone position (geniohyoid, sternohyoid, etc.); (2) the muscle of the tongue (genioglossus); and (3) the muscles of the palate (tensor palatini, levator palatini). The activity of many of these muscles is increased inspiration (“phasic muscles”) thus stiffening and dilating the upper airway thereby counteracting during the collapsing influence of negative airway pressure
Central ventilatory instability • The term loop gain is used to refer to the intrinsic stability or instability in the ventilatory control system. • A system with high loop gain would be relatively unstable requiring only a minor perturbation to yielding periodic breathing. • A system with low loop gain would be intrinsically stable with a regular breathing pattern persisting despite a major perturbation. • Cyclical oscillations from the central pattern generator in the brainstem could therefore yield upper airway collapse when output to the pharyngeal dilator muscles was at its nadir in an individual who was anatomically predisposed. • Most studies failed to demonstrate a relationship between the higher susceptibility to OSA seen in men or with agingto this ventilatory control instability .
Central ventilatory instability • Since the prevalence of central sleep apnea appears to be increased in the elderly, it is possible that factors which promote the development of central apnea may be enhanced by aging. For example, an increased ventilatory response to hypercapnia can promote the development of sleep apnea by destabilizing the chemical control of breathing. • However, it appears that the ventilatory response to hypercapnia during euoxic wakefulness is not altered by aging. In fact, the sensitivity of the hypercapnic ventilatory response may be reduced during hypoxia in the elderly . • The change in the ventilatory response to hypercapnia during transition from wakefulness to sleep also influences the development of central sleep apnea.
Central ventilatory instability • Normally, the hypercapnic ventilatory response is reduced during this transition, which helps to stabilize breathing during sleep. Loss of this stabilizing response during aging could promote the development of central apnea. • Comparison of loop gain in healthy young and elderly subjects found no significant difference between them . Consequently there is no convincing evidence that aging per se destabilizes the control of breathingand that age-related changes in the control of breathing are responsible for the increased prevalence of sleep apnea in the elderly.
Central ventilatory instability • Termination of the apnea generally requires a transient arousal from sleep thus activating the upper airway muscles and re-establishing airway patency. • Without such an arousal, profound hypoxemia and hypercapnia would likely ensue. • The possible mechanisms leading to arousal, include direct stimulation of peripheral and central chemoreceptors by rising PaCO2 and falling PaO2, afferent CNS input from the lung, chest wall, or upper airway receptors resulting from the increasing ventilatory effort that develops over the course of an apnea, or direct stimulation of the reticular activating system by respiratory neurons activated by the apnea process • Arousal remains an important mechanism by which apneas are terminated, but at the same time arousals may increase the severity of the sleep disordered breathing by promoting greater ventilatory instability
Chronic medical disorders that are associated with sleep apnea • The prevalence of chronic medical disorders increases with advancing age and many of them, such as heart failure, stroke and renal failure, are associated with the development of sleep apnea. • Congestive heart failureover 65 years, 71% of those whose left ventricular ejection fraction was < 40% had sleep apnea, defined as an AHI greater than 10. Forty-three percent of patients had OSA and 28% had Cheyne-Stokes respiration. • The prevalence of sleep apnea is high in patients who have suffered a stroke; 53% of patients with an acute stroke had sleep apnea, reflected by an AHI >10. • The prevalence of sleep apnea in end-stage renal disease has been reported to be atleast 60% in middle-aged patients.
Clinical presentation of sleep apnea • Significant proportion of elderly patients may have asymptomatic sleep apnea, • Elderly patients with sleep apnea can present with typical clinical features such as: 1- Daytime sleepiness. 2-Snoring, 3-Choking or gasping respirations, 4-Witnessed apneas, 5-Morning headaches, 6-Hypertension
Clinical presentation of sleep apnea • it is important to recognize that sleep apnea may also be heralded by atypical symptoms that are unique to this age group. 1- Enuresis may be a consequence of sleep disordered breathing in the elderly , and can be improved with effective treatment of sleep apnea. 2- Nocturnal wandering or confusion may be associated with sleep apnea . 3- Cognitive impairment, measured by Mini-Mental State Examination, delayed verbal recall, and impaired constructional abilities, and even dementia, have all been described in the elderly with sleep apnea. 4- Falls during the day or night-time are associated with sleep disordered breathing , 5- Ocular conditions associated with OSA eg. glaucoma and non arteritic anterior ischemic optic neuropathy (NAION).
Clinical presentation of sleep apnea • In the middle-aged population, anthropomorphic features, such as BMI, neck and waist circumference , history of snoring and nocturnal choking, are significantly associated with the AHI and, hence, are considered predictive of sleep apnea . • One study has demonstrated that these typical anthropomorphic features and symptoms are also predictive of sleep apnea in the elderly.
Clinical presentation of sleep apnea • At age 40 the odds ratio for a positive association between BMI and AHI was 2.0 , but by age 80 it was 1.3. Neck circumference was no longer a significant predictor of AHI by age 80 and waist-to-hip ratio was no longer significant by age 70. • This suggests that anthropomorphic features used to predict sleep apnea in middle aged subjects may not be as robust in the elderly. • In addition, a history of snoring was noted to decrease 1.8-fold from age 50–60 to age 70 and beyond, indicating that typical symptoms of sleep apnea may not be reported as frequently in the elderly.
Diagnosis of sleep apnea • Comprehensive overnight polysomnography in the sleep laboratory is the gold standard for the diagnosis of sleep disordered breathing . • Alternative diagnostic testing includes nocturnal cardiopulmonary monitoring (i.e. without sleep monitoring) and polysomnography at home. • Studies that have evaluated these diagnostic modalities have not included elderly subjects, and consequently we are left to extrapolate from studies on younger subjects. • Cardiopulmonary monitoring in middle-aged subjects has been found to be as effective as polysomnography in predicting which patients will benefit from continuous positive airway pressure therapy .
Diagnosis of sleep apnea • Comparing cardiopulmonary monitoring with polysomnography in selected patients with a high probability of OSA found no difference in their outcome measurements, which included AHI on CPAP, daytime sleepiness, quality of life, and CPAP requirement . • Although these data suggest that cardiopulmonary monitoring may be adequate to diagnose sleep apnea in selected elderly subjects, this needs to be confirmed
Diagnosis of sleep apnea • This suggestion is supported by the fact that the elderly have some unique factors that may confound the accurate interpretation of limited diagnostic testing. For example, the high proportion of central apnea and increased prevalence of periodic limb movements in the elderly may require monitoring of respiratory effort and leg movements, respectively. • Some elderly subjects are not capable of setting up a monitoring system at home either because of infirmity and/or lack of family support; in such cases, attended monitoring in a sleep laboratory may be the best option.
