Section 10 Sleep-Related Breathing Disorders
10.1 Obstructive Sleep Apnea
AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications, pp 45-49.
Polysomnography for sleep breathing disorders: scoring rules for adults (Atlas, p 269; Manual, pp 45-47)
Hypopnea
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A 38-Year-Old Man with a History of Scrotal Edema
The patient is a 38-year-old real estate agent who presents in mid-January with a 15-year history of snoring, a 2-year history of witnessed apnea, and excessive daytime sleepiness. The patient has an Epworth Sleepiness Scale score of 17. Twelve months previously the patient started to notice swelling of his feet and ankles, and during the course of the year he developed severe edema, which peaked on New Year’s Eve when his edema was so severe that it resulted in swelling of his testicles and legs. He was admitted to the hospital and was told that he had heart failure. He was treated with heart failure medications, and he lost 60 pounds by the time of discharge, 1 week later. He was sent for a sleep evaluation immediately after discharge. A fragment from his sleep study is shown in Figure 10.1–1. The top window is a 30-second epoch, the bottom is a 2-minute epoch.
6 The patient is started on treatment after 2 hours of monitoring. A fragment from the PSG is shown in Figure 10.1–2. What does this fragment show? C-flow is mask flow measured by the CPAP unit.
Frantic Call from the Sleep Tech
A 48-year-old patient, complaining of snoring and daytime sleepiness, is in the sleep laboratory having overnight polysomnography. He is on oxycodone for pain. The night tech phones the on-call doctor with concerns that the patient is having a dysrhythmia “issue” and he does not know how to proceed. The tech captures the PSG screen and sends the image file to the on-call doctor by e-mail. The PSG fragment in Figure 10.1–3 shows a 60-second epoch.
A 67-year-old female patient with a BMI of 29 has a history of snoring and insomnia. She is in the hospital for a minor elective orthopedic procedure. In the postanesthesia area she is noted to snore loudly. The surgeon orders a sleep test consisting only of oximetry, which is done by the respiratory therapy department and is interpreted by a pulmonologist who interprets such tests for a company doing home testing. He interprets the test as consistent with mild sleep apnea and prescribes a nasal mask and an autotitrating CPAP machine (pressure range 5-10 cm H2O). The patient was sent home with such a machine, but now she is more fatigued than before and can’t fall asleep on the CPAP. She is then referred to a sleep clinic by her family doctor for a second opinion. She brings in the recording shown in Figure 10.1–4.
11 What might explain the change in the pattern of oximetry that occurs at about 2 hours 20 minutes (the vertical red line in the figure) into the night?
Obstructive Apnea Comorbidities
14 A 38-year-old truck driver with a snoring history is referred to be evaluated for sleep apnea. The patient cannot attend the lab for a sleep study for a week because he will be driving a long-haul tractor-trailer and will be on the road. His Epworth Sleepiness Scale score is 24. What do you advise the patient?
A Because he has obviously had this for some time, advise him not to worry until he can have the test.
15 A 48-year-old female patient with fatigue and insomnia presents to her primary care practitioner. He gives her the Berlin Questionnaire to fill in. This instrument is used to calculate the risk of what condition?
17 A 40-year-old female with a BMI of 50 is being referred to the sleep disorders center to screen for sleep problems prior to bariatric surgery. She is noted to have severe swelling of the ankles. What abnormality most likely would explain the peripheral edema?
18 A 55-year-old woman with a history of obesity (BMI = 35), hypertension, and snoring was found to have OSA with an apnea index of 15. During her titration study (Fig. 10.1–5) the tech notes that she believes that the patient has had an episode of ventricular tachycardia and sent the patient to the emergency room. What is the patient’s cardiac rhythm based on what is seen in the 2-second zoomed window?
Not Just Middle-Aged Obese Men
19 A thin 6-year-old patient is referred to the sleep disorders center with a history of restless sleep. The patient’s exam of his pharynx is pictured in Figure 10.1–6. What do you note in the chart?
22 A 48-year-old woman is referred with a history of excessive daytime sleepiness, difficulty in falling asleep and staying asleep, snoring, and the observation that she stops breathing during sleep. She wakes up quite frequently short of breath. She had a myocardial infarction at age 44 years and has long-standing hypertension and diabetes. She has a BMI of 51, BP of 160/110. Physical examination reveals peripheral edema, severe acne, and excessive facial hair. Severe apnea with an AHI of 70 was documented. What is the likeliest underlying medical problem?
23 A patient with abnormal liver enzymes related to nonalcoholic fatty liver disease is referred for evaluation because of daytime sleepiness. What sleep disorder is likely in this patient?
26 When female and male patients are matched for apnea severity, age, and sleepiness, which statement about clinical presentation of obstructive sleep apnea in women is true?
1 C. The EEG shows sharp waves, but they are very frequent and correspond perfectly with the electrocardiogram trace. Therefore, the EEG channels are contaminated with an EKG artifact. Vertex sharp waves are much less frequent and are a marker of stage NI sleep. Sawtooth waves and rapid eye movements are found in stage REM and are not present in this fragment. Atlas, pp 263, 264, 266, 342
2 B. The snoring channel shows increased activity during the resumption of breathing. Between clusters of increased snoring channel activity there is no activity corresponding to the patient’s being quiet. The movements here correspond to breathing and are not a result of a periodic limb movement because only one movement is seen and that occurs when the patient resumes breathing. Excessive sweating might be noted if the EEG channels demonstrated a sweat artifact, which is noted as very high amplitude low-frequency waves superimposed on the EEG and synchronous with breathing. Atlas, p 343
3 B. This is classic obstructive sleep apnea. There is a marked reduction in air flow while respiratory effort is noted in the thoracic and abdominal belts. Note that both the temperature-sensing channel and nasal pressure channels are markedly reduced or at times zero. By AASM guidelines the air temperature sensor channel (thermistor or thermocouple) is used to document apnea, and nasal pressure is used to document hypopnea. Nasal pressure reads zero when the patient is breathing through the mouth. Thus nasal pressure is not always a reliable indicator of apnea. Atlas, p 283
4 D. The evidence points to cor pulmonale as the most likely cause of this patient’s peripheral edema. This refers to right heart failure secondary to respiratory failure. In the presence of severe hypoxemia, there occurs the development of pulmonary hypertension, which eventually can result in right ventricular failure, increased venous pressure, and the development of peripheral edema. If there had been a Cheyne-Stokes breathing pattern, then left heart failure would likely have been an important contributor as well. Atlas, p 166
5 A. The next step is CPAP titration because obstructive sleep apnea was documented. Adaptive servoventilation would be used if a Cheyne-Stokes breathing pattern or central apneas had been present. Oxygen therapy is not effective in treating obstructive sleep apnea. The patient’s apnea and hypoxemia are too severe for the patient to be considered for therapy with a mandibular advancement device.
6 D. The flattening of the flow trace in the middle of the bottom epoch is evidence for flow limitation. Thus, the airway is still obstructed. Toward the right side, notice that the flow trace now demonstrates a rounded top during unobstructed breathing. Evaluating the shape of the flow trace is very valuable. Figure 10.1–7 is an enlargement of the C-flow trace from the middle of the epoch showing flattening of the top of the trace indicating flow limitation (left) and from later in the epoch showing a rounded top indicating unobstructed breathing (right).
7 A. Because flow limitation has been demonstrated, the next step would be to increase the CPAP pressure. Reducing the pressure would increase flow limitation and obstruction, adaptive servoventilation is not indicated at all, and in the absence of central apnea, bilevel pressure with a backup rate is not indicated.
8 C. Inspiring against an obstructed airway is similar to the Mueller maneuver, which increases vagal tone, which can cause bradycardia or, as in this example, sinus arrest. Atlas, p 315
9 C. Central apnea is present in this fragment because the lack of airflow (monitored by thermal sensor and nasal pressure) occurs when there is no effort to breathe. Central apnea episodes can occur in patients with primarily obstructive apnea, especially if they are using opiate medications. Snoring noises were present when breathing resumed. Atlas, p 299
10 C. This is not a rare finding in OSA patients. Such rhythm abnormalities are usually corrected by CPAP treatment. Inexperienced technologists sometimes send such patients to the emergency room, and pacemakers have been inappropriately inserted in such patients.
11 D. All of the answers are possible. One cannot tell from oximetry alone the accurate severity of this patient’s problem, and if apnea were present, it could not determine apnea type.
12 D. Simply changing the pressure setting is not going to be helpful, because a firm diagnosis has not been established. Stopping the PAP therapy is also the wrong course of action because the patient did have documented significant hypoxemia by oximetry. Prescribing a hypnotic at this point is contraindicated. A subsequent in-lab sleep study showed that the patient had very severe obstructive apnea and very severe periodic limb movement disorder. The latter obviously could not have been detected with oximetry. Ultimately, both sleep disorders were treated and the patient has done well.
13 D. The commonest causes of sleepiness in a university student are sleep deprivation (often caused by delayed sleep phase), sleep apnea, depression, medication use, and narcolepsy, in that order. The MWT is not used to diagnose any of those. An MSLT without a preceding PSG cannot rule out abnormalities during sleep causing the symptom. There is no indication from what has been presented to included epilepsy in the differential diagnosis. The clinical history suggests the features of Hodgkin’s lymphoma. This disease enlarges lymphatic tissue in lymph nodes in the neck and tonsils, and narrowing of the upper airway by any anatomic cause from any cause can lead to obstructive apnea. Imaging studies would be helpful. The correct sleep evaluations in managing this case would be a PSG followed by MSLT if no sleep pathology is found, but this was not one of the choices. Espinosa et al, 1996
14 B. The last question on the Epworth Sleepiness Scale refers to falling asleep while stopped for a few minutes while operating a motor vehicle. Thus the patient is a hazard on the road and answer A is incorrect. Answers C and D are incorrect because the patient would be treated without a diagnosis. This leaves answer B. The patient should be advised not to drive until he has been evaluated and treated. Atlas, p 90
15 A. This is a questionnaire that surveys snoring, sleepiness, and risk factors to yield whether a patient is at risk for having OSA. Atlas, p 90
16 B. Cor pulmonale is right heart failure caused by pulmonary hypertension. The likeliest patients to have this in a sleep clinic are patients with COPD with the overlap syndrome and patients with obesity hypoventilation syndrome. Weitzenblum et al, 2009
17 C. In a patient with morbid obesity and severe swelling of the ankles it is likely that cor pulmonale caused by hypoventilation is present. When CO2 is elevated during the daytime, the term obesity hypoventilation is used. Mokhlesi et al, 2008
18 C. There is not a single cardiac cycle clearly visible in the zoomed window. There are 20 cycles seen in one second. That results in a rate of 1200, which is faster than any known tachyarrhythmia. Paroxysmal ventricular tachycardia has a rate of up to 250, and torsades de pointes and ventricular flutter can be up to 350. Thus in this example, the zoomed window is helpful in determining what the rhythm is not. Obviously, sending the patient to the ER was a very costly error.
19 A. The tonsils are remarkably enlarged and meet in the midline. Tonsils are from 0 (not present) to 4 (meeting in the midline). Mallampati score documents relationship of tongue to the pharyngeal size and ranges from class I (all structures visible) to IV (soft palate not visible). Enlarged tonsils are the most common cause of apnea in children. Atlas, p 159-162
20 B. Children with Prader-Willi syndrome often become morbidly obese; their main sleep complaint is hypersomnia, often with sleep apnea. SOREMPs may be seen on MSLT. Elevated ghrelin might explain the hyperphagia of these patients. Williams, 2008
21 A. In one series, all patients with Prader-Willi syndrome had some form of sleep-disordered breathing. GH secretion is usually decreased in Prader-Willi syndrome. GH therapy has been recommended from early childhood. GH therapy results in height gain and can improve psychomotor development. Obstructive apnea can occur in cases in which there is a rapid increase in the dose of GH. Data are inconsistent on the effect of growth hormone on SDB in Prader-Willi syndrome. Castinetti et al, 2008; Goldstone et al, 2008
22 B. Although sleep apnea can occur with each of the conditions mentioned, the history and findings are classic for polycystic ovary syndrome. The ovaries of these patients have multiple cysts that produce excess androgenic hormone, hence the hirsutism and acne. They are about seven times more likely than controls to have OSA (20% to 50% of cases have OSA), and those with OSA are more likely to have insulin resistance. The history also includes abnormal or absent menstrual cycle and difficulty in becoming pregnant. Atlas, p 245; Tasali, 2008
23 D. About half of patients with nonalcoholic fatty liver disease (NAFLD; also called nonalcoholic steatohepatitis [NASH]) have features of sleep apnea. Research in animals indicates that chronic intermittent hypoxia predisposes to liver injury. The presence of sleep apnea predicts the development of NAFLD and the presence of histologic findings of NAFLD. Singh et al, 2005, Savransky et al, 2007, Campos et al, 2008, Mishra et al, 2008
24 B. The prevalence of sleep apnea in menopausal women is similar to that of age matched male controls. The reasons for the increase in sleep apnea prevalence in women during the menopausal transition are not known. There are many theories, including the withdrawal of estrogen and progesterone and a redistribution of fat. Significant obesity might not be an important factor because the weight gain with menopause is usually modest. There is no known relationship of sleep apnea with hot flushes. Sleep apnea responds as well in women as in men.
25 B. Snoring in pregnancy has been linked statistically with preeclampsia and with smaller-than-expected babies, who have a lower Apgar score than children of nonsnoring women. Sleep apnea in pregnant women should be treated because of the potential negative effect on the developing baby. The most common cause of nocturnal awakenings in pregnancy is nocturia. Atlas, p 245
26 A. Insomnia is much more common in female than male patients with obstructive sleep apnea. Studies comparing the presentation of men and women have shown that women are much more likely to also have a history of depression, antidepressant use, and thyroid disease. In men, caffeine consumption is greater. Shepertycky et al, 2005
27 D. In premenopausal women, obstructive events often tend to cluster in REM sleep compared to men. The reason for this is not well understood. One possible explanation is that in women in the upper airway is less compliant than in men. O’Connor et al, 2000
28 A. Sleep apnea is found in all the conditions, but the most common cause of sleep apnea in children is enlargement of the tonsils and adenoids. Children with sleep apnea present with snoring and observed apnea at times. The presentation is with restless sleep, falling asleep in the classroom, or even with a diagnosis of attention-deficit/hyperactivity disorder.
Summary
Must Read
AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications, pp 45-49.
Pathophysiology
Diagnostic Methods
Polysomnography for sleep breathing disorders: scoring rules for adults (Atlas, p 269; Manual, pp 45-47)
Hypopnea• Definition 1 (Medicare hypopnea): at least 30% drop in nasal pressure amplitude, for at least 90% of the event, with at least a 4% drop in SaO2
