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ABP Sleep Medicine study materials
ABP Sleep Medicine study resources

ABP Sleep Medicine practice questions

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Question 1Normal Sleep and Sleep-Wake Regulation

In a healthy adult, approximately what proportion of total nocturnal sleep time is spent in REM sleep?

  1. About 75%
  2. About 50%
  3. About 20-25% Correct answer.
  4. About 5%

Explanation

In adults, REM sleep typically occupies roughly 20-25% of total sleep time, cycling approximately every 90 minutes across the night. The proportion is higher in infants and declines with age.

Question 2Normal Sleep and Sleep-Wake Regulation

Which EEG pattern is the defining hallmark of stage N2 sleep?

  1. Sleep spindles and K-complexes Correct answer.
  2. Sawtooth waves
  3. Delta waves occupying over 20% of the epoch
  4. Alpha rhythm

Explanation

Stage N2 is defined by the presence of sleep spindles and/or K-complexes in the absence of sufficient slow-wave activity. These transient waveforms distinguish N2 from N1 and N3.

Question 3Normal Sleep and Sleep-Wake Regulation

The circadian pacemaker that generates the body's endogenous ~24-hour rhythm is located in which structure?

  1. Raphe nuclei
  2. Suprachiasmatic nucleus of the hypothalamus Correct answer.
  3. Pineal gland
  4. Locus coeruleus

Explanation

The suprachiasmatic nucleus of the anterior hypothalamus serves as the master circadian clock, entrained primarily by light. It coordinates peripheral clocks and drives rhythms such as melatonin secretion and core temperature.

Question 4Normal Sleep and Sleep-Wake Regulation

Which neurotransmitter is released by neurons of the ventrolateral preoptic nucleus to promote sleep?

  1. Acetylcholine
  2. Histamine
  3. Orexin
  4. GABA Correct answer.

Explanation

Ventrolateral preoptic nucleus neurons are inhibitory and release GABA (and galanin) to suppress wake-promoting arousal systems. This forms the sleep side of the flip-flop switch model of sleep-wake control.

Question 5Normal Sleep and Sleep-Wake Regulation

Arousal from REM sleep is most strongly suppressed by which feature of REM physiology?

  1. Increased heart rate variability
  2. Elevated core temperature
  3. High muscle tone
  4. Skeletal muscle atonia Correct answer.

Explanation

REM sleep is characterized by skeletal muscle atonia mediated by brainstem inhibition of alpha motor neurons, which prevents acting out of dreams. This atonia is a defining feature of REM.

Question 6Normal Sleep and Sleep-Wake Regulation

Which EEG frequency band corresponds to alpha activity seen in relaxed wakefulness with eyes closed?

  1. 0.5-4 Hz
  2. 8-13 Hz Correct answer.
  3. 4-7 Hz
  4. 14-30 Hz

Explanation

Alpha activity is conventionally defined as 8-13 Hz and is prominent over occipital regions during relaxed wakefulness with eyes closed. It attenuates with eye opening or mental activation.

Question 7Normal Sleep and Sleep-Wake Regulation

In a typical adult sleep cycle, which sequence best describes the progression of sleep stages after sleep onset?

  1. N2, then N1, then REM, then N3
  2. REM, then N1, then N2, then N3
  3. N1, then N2, then N3, then REM Correct answer.
  4. N3, then N2, then N1, then REM

Explanation

After sleep onset, adults typically pass from N1 into N2, then into N3 slow-wave sleep, before entering the first REM period. This cycle repeats roughly every 90 minutes through the night.

Question 8Normal Sleep and Sleep-Wake Regulation

Slow-wave sleep (stage N3) predominates during which part of a normal night's sleep?

  1. The middle third of the night
  2. The first third of the night Correct answer.
  3. Evenly distributed across the night
  4. The final third of the night

Explanation

Slow-wave sleep is front-loaded, occurring predominantly in the first third of the night. REM sleep, by contrast, is concentrated in the later part of the night.

Question 9Normal Sleep and Sleep-Wake Regulation

Which of the following best describes the homeostatic sleep drive in the two-process model of sleep regulation?

  1. An accumulating pressure that rises with time awake and dissipates with sleep Correct answer.
  2. A circadian oscillator independent of prior wakefulness
  3. A process driven solely by ambient light exposure
  4. A rhythm that peaks in the early evening

Explanation

Process S, the homeostatic component, builds as a function of prior wakefulness and declines during sleep. It interacts with the circadian process C to determine sleep timing and depth.

Question 10Normal Sleep and Sleep-Wake Regulation

Melatonin secretion from the pineal gland is typically suppressed by which condition?

  1. Reduction in core body temperature
  2. Sleep onset
  3. Prolonged darkness
  4. Exposure to bright light at night Correct answer.

Explanation

Melatonin secretion is suppressed by light exposure, particularly bright light at night, via a retinohypothalamic pathway to the suprachiasmatic nucleus. Darkness permits melatonin release.

Question 11Normal Sleep and Sleep-Wake Regulation

The circadian rhythm of core body temperature in humans normally reaches its minimum at approximately what time?

  1. Around 6 PM
  2. At midday
  3. Immediately after the largest meal
  4. In the late night to early morning, near the habitual wake time Correct answer.

Explanation

Core temperature typically reaches its nadir in the late night or early morning, a few hours before habitual awakening. This temperature minimum is a commonly used circadian phase marker.

Question 12Normal Sleep and Sleep-Wake Regulation

In the standard AASM sleep staging, stage N1 is defined by which EEG finding?

  1. Sleep spindles occupying more than 50% of the epoch
  2. Delta waves occupying more than 20% of the epoch
  3. Alpha rhythm occupying more than 50% of the epoch
  4. Attenuation of alpha rhythm with predominantly low-amplitude mixed-frequency activity Correct answer.

Explanation

N1 is characterized by attenuation of alpha rhythm and replacement with low-amplitude, mixed-frequency EEG activity, often with vertex sharp waves. Alpha occupying over 50% of an epoch indicates wakefulness.

Question 13Normal Sleep and Sleep-Wake Regulation

Which sleep stage is associated with the highest arousal threshold to external stimuli in healthy adults?

  1. Stage N2
  2. Stage REM
  3. Stage N3 Correct answer.
  4. Stage N1

Explanation

Stage N3 slow-wave sleep generally has the highest arousal threshold, meaning stronger stimuli are required to produce awakening. REM has a lower threshold than N3 despite its muscle atonia.

Question 14Normal Sleep and Sleep-Wake Regulation

A person working a rotating night shift develops insomnia and daytime sleepiness. Which circadian phenomenon most directly explains this?

  1. Desynchrony between the endogenous circadian rhythm and the required sleep-wake schedule Correct answer.
  2. Excessive homeostatic sleep drive from too little time in bed
  3. Reduced total REM sleep percentage
  4. Increased slow-wave sleep in the daytime

Explanation

Shift work forces sleep and wakefulness to occur out of phase with the endogenous circadian clock, producing circadian desynchrony. This misalignment drives insomnia and excessive sleepiness.

Question 15Normal Sleep and Sleep-Wake Regulation

Which of the following best characterizes the EEG pattern of REM sleep?

  1. Continuous alpha rhythm
  2. Low-amplitude mixed-frequency activity resembling wakefulness Correct answer.
  3. High-amplitude delta activity with sleep spindles
  4. Frequent K-complexes with slow waves

Explanation

REM sleep EEG is low-amplitude and mixed-frequency, often resembling relaxed wakefulness, which is why it is termed paradoxical sleep. Sawtooth waves may also appear.

Question 16Normal Sleep and Sleep-Wake Regulation

Arousal from sleep is mediated primarily by which ascending system?

  1. The dorsal column-medial lemniscus pathway
  2. The parasympathetic vagal outflow
  3. The ascending reticular activating system and its cholinergic and monoaminergic projections Correct answer.
  4. The corticospinal tract

Explanation

The ascending reticular activating system, with cholinergic and monoaminergic projections to the cortex and thalamus, drives wakefulness and arousal. Its suppression underlies sleep onset.

Question 17Normal Sleep and Sleep-Wake Regulation

In the flip-flop model of sleep-wake regulation, which two mutually inhibitory groups form the core switch?

  1. The suprachiasmatic nucleus and the pineal gland
  2. The thalamus and the cerebellum
  3. Sleep-promoting VLPO neurons and wake-promoting arousal nuclei Correct answer.
  4. The amygdala and the hippocampus

Explanation

The flip-flop model describes mutual inhibition between sleep-promoting VLPO neurons and wake-promoting monoaminergic and orexinergic nuclei. This arrangement produces stable, switch-like transitions between sleep and wake states.

Question 18Normal Sleep and Sleep-Wake Regulation

Which statement about sleep spindles is most accurate?

  1. They are 11-16 Hz bursts lasting at least 0.5 seconds, prominent over central regions Correct answer.
  2. They occur exclusively in REM sleep
  3. They are identical to K-complexes in morphology
  4. They are 1-4 Hz waves prominent over frontal regions

Explanation

Sleep spindles are bursts of 11-16 Hz activity lasting at least 0.5 seconds, maximal over central derivations, and are a defining feature of N2. They are generated by thalamocortical circuits.

Question 19Normal Sleep and Sleep-Wake Regulation

Total sleep time and the proportion of slow-wave sleep typically change with age in which pattern?

  1. Total sleep time and slow-wave sleep both decline from childhood into older adulthood Correct answer.
  2. Total sleep time decreases while slow-wave sleep increases
  3. Both remain constant across the lifespan
  4. Total sleep time increases while slow-wave sleep decreases

Explanation

Across the lifespan, total sleep time and the proportion of slow-wave sleep both decline, with the steepest reductions occurring in early life and continuing into older adulthood. Sleep becomes lighter and more fragmented with age.

Question 20Normal Sleep and Sleep-Wake Regulation

Which finding on polysomnography is most consistent with the transition from wakefulness to stage N1 sleep?

  1. Rapid eye movements with muscle atonia
  2. Slow rolling eye movements and alpha attenuation Correct answer.
  3. Delta waves occupying more than 20% of the epoch
  4. Appearance of sleep spindles

Explanation

The wake-to-N1 transition is marked by alpha attenuation and the emergence of slow rolling eye movements. Vertex sharp waves may follow as sleep deepens.

Question 21Sleep-Related Breathing Disorders

Which apnea-hypopnea index (AHI) threshold defines severe obstructive sleep apnea in adults?

  1. 60 events per hour
  2. 15 events per hour
  3. 5 events per hour
  4. 30 events per hour Correct answer.

Explanation

Adult OSA severity is graded by AHI: 5-14.9 is mild, 15-29.9 is moderate, and 30 or more events per hour is severe.

Question 22Sleep-Related Breathing Disorders

By standard adult scoring criteria, an apnea is defined as a reduction in airflow lasting at least how long?

  1. 5 seconds
  2. 10 seconds Correct answer.
  3. 20 seconds
  4. 30 seconds

Explanation

An apnea requires a drop in peak airflow of at least 90 percent lasting 10 seconds or longer. The 10-second duration is the minimum event length used in adult scoring.

Question 23Sleep-Related Breathing Disorders

Which finding on nocturnal polysomnography most directly identifies an obstructive rather than central apnea?

  1. Presence of continued respiratory effort during airflow cessation Correct answer.
  2. Presence of an arousal at event termination
  3. Absence of respiratory effort during the event
  4. A fall in oxygen saturation during the event

Explanation

Obstructive apneas are characterized by ongoing respiratory effort against a closed or narrowed airway while airflow stops. Central apneas show absent effort.

Question 24Sleep-Related Breathing Disorders

A 55-year-old man with loud snoring, witnessed apneas, and daytime sleepiness undergoes testing. Which test is the reference standard for diagnosing OSA?

  1. Home overnight oximetry alone
  2. Overnight attended polysomnography Correct answer.
  3. Berlin Questionnaire result
  4. Epworth Sleepiness Scale score

Explanation

Attended in-laboratory polysomnography is the reference standard because it quantifies apneas, hypopneas, oxygen saturation, and sleep architecture simultaneously. Questionnaires and oximetry are screening or limited tools.

Question 25Sleep-Related Breathing Disorders

Which of the following is the most common major risk factor for obstructive sleep apnea in adults?

  1. Hypothyroidism
  2. Female sex
  3. Chronic kidney disease
  4. Obesity Correct answer.

Explanation

Obesity, particularly central adiposity, is the strongest and most prevalent modifiable risk factor for adult OSA. Weight gain increases pharyngeal collapsibility and airway fat deposition.

Question 26Sleep-Related Breathing Disorders

Which class of medication is most likely to worsen obstructive sleep apnea by depressing ventilatory drive and relaxing upper airway musculature?

  1. Beta-blockers
  2. Benzodiazepines Correct answer.
  3. Proton pump inhibitors
  4. Inhaled corticosteroids

Explanation

Benzodiazepines and other sedative-hypnotics reduce arousability and upper airway muscle tone, potentially lengthening apneas and worsening hypoventilation. They should be used cautiously in patients with OSA.

Question 27Sleep-Related Breathing Disorders

Which condition is most strongly associated with central sleep apnea in adults?

  1. Chronic sinusitis
  2. Gastroesophageal reflux disease
  3. Asthma
  4. Heart failure with reduced ejection fraction Correct answer.

Explanation

Central sleep apnea, particularly Cheyne-Stokes respiration, is strongly associated with heart failure due to prolonged circulation time and increased chemosensitivity. Loop gain instability drives the periodic breathing pattern.

Question 28Sleep-Related Breathing Disorders

Positive airway pressure therapy for OSA primarily works by which mechanism?

  1. Increasing central respiratory drive
  2. Splinting the upper airway open Correct answer.
  3. Suppressing arousals directly
  4. Reducing body weight

Explanation

CPAP delivers a pneumatic splint that maintains upper airway patency during sleep, preventing collapse. It does not alter central drive or body weight.

Question 29Sleep-Related Breathing Disorders

A patient with OSA has an AHI of 22 events per hour on a diagnostic study. How is severity classified?

  1. Severe
  2. Mild
  3. Normal
  4. Moderate Correct answer.

Explanation

An AHI between 15 and 29.9 events per hour falls in the moderate range. Mild is 5-14.9 and severe is 30 or more.

Question 30Sleep-Related Breathing Disorders

A 48-year-old woman has an AHI of 9 events per hour with daytime sleepiness and hypertension. Which management is most appropriate as initial therapy?

  1. Reassurance without intervention
  2. Immediate tracheostomy
  3. Upper airway stimulation surgery
  4. Weight management and discussion of PAP or oral appliance therapy Correct answer.

Explanation

Mild OSA with symptoms and comorbidity warrants treatment, typically beginning with weight management and PAP or an oral appliance. Tracheostomy and hypoglossal nerve stimulation are reserved for selected cases.

Question 31Sleep-Related Breathing Disorders

A patient on CPAP has a residual AHI of 18 events per hour at a fixed pressure of 10 cm H2O. What is the most appropriate next step?

  1. Switch to a mouth guard without further evaluation
  2. Add supplemental oxygen alone
  3. Discontinue CPAP
  4. Review adherence and consider pressure titration or auto-PAP Correct answer.

Explanation

Persistent events on PAP suggest inadequate pressure or poor adherence. Reviewing usage data and retitrating or using auto-adjusting PAP is the appropriate response.

Question 32Sleep-Related Breathing Disorders

Which finding best distinguishes an obstructive hypopnea from a central hypopnea on polysomnography?

  1. Event duration greater than 10 seconds
  2. Presence of oxygen desaturation
  3. Presence of an arousal
  4. Continued inspiratory effort during the event Correct answer.

Explanation

The effort signal differentiates the two: obstructive hypopneas show ongoing respiratory effort, whereas central hypopneas show reduced or absent effort. Desaturation, arousal, and duration occur with both.

Question 33Sleep-Related Breathing Disorders

A patient with heart failure and Cheyne-Stokes respiration has predominantly central apneas. Which therapy is most appropriate to consider?

  1. Uvulopalatopharyngoplasty
  2. Mandibular advancement device
  3. Adaptive servo-ventilation or optimization of heart failure therapy Correct answer.
  4. Fixed high-pressure CPAP alone

Explanation

Central sleep apnea in heart failure is managed by optimizing cardiac therapy and, in selected patients, adaptive servo-ventilation. Surgical and dental options target obstructive anatomy.

Question 34Sleep-Related Breathing Disorders

Which polysomnographic feature is characteristic of obesity hypoventilation syndrome?

  1. Normal bicarbonate with severe desaturation
  2. Awake hypercapnia with a body mass index of 30 or greater Correct answer.
  3. Isolated central apneas with normal ventilation
  4. Nocturnal hypoxemia with normal awake blood gas

Explanation

Obesity hypoventilation syndrome is defined by awake hypercapnia (PaCO2 above 45 mm Hg) in a patient with obesity (BMI 30 or greater) after other causes are excluded. It often coexists with OSA.

Question 35Sleep-Related Breathing Disorders

A patient reports excessive daytime sleepiness and has a high pretest probability of OSA but no significant cardiopulmonary comorbidity. Which approach is reasonable for diagnosis?

  1. Empiric CPAP without any testing
  2. Home sleep apnea testing with a type 3 device Correct answer.
  3. Awake arterial blood gas analysis
  4. Multiple sleep latency test

Explanation

Home sleep apnea testing is acceptable for adults with a high pretest probability of moderate-to-severe OSA and no significant comorbidity. It is not appropriate for patients with major cardiopulmonary disease or suspected central apnea.

Question 36Sleep-Related Breathing Disorders

Which craniofacial feature increases the risk of obstructive sleep apnea?

  1. Prognathia
  2. High-arched palate alone
  3. Retrognathia Correct answer.
  4. Class I occlusion

Explanation

Retrognathia and micrognathia narrow the posterior airway space and predispose to pharyngeal collapse. This is a well-recognized anatomic risk factor.

Question 37Sleep-Related Breathing Disorders

A patient's polysomnogram shows repetitive events with continued effort, oxygen desaturation, and arousals occurring predominantly in the supine position. What does this suggest?

  1. Positional obstructive sleep apnea Correct answer.
  2. Sleep-related hypoventilation
  3. Central sleep apnea
  4. Narcolepsy

Explanation

Events that occur primarily in the supine position with continued effort indicate positional OSA. Supine AHI is often substantially higher than non-supine AHI in these patients.

Question 38Sleep-Related Breathing Disorders

Which therapy is most appropriate for a patient with severe OSA who cannot tolerate CPAP and has not responded to an oral appliance?

  1. Nasal decongestants
  2. Observation alone
  3. Hypoglossal nerve stimulation in an appropriate candidate Correct answer.
  4. Weight loss alone

Explanation

Hypoglossal nerve stimulation is an option for selected CPAP-intolerant patients with moderate-to-severe OSA who meet anatomic and titration criteria. Other options are inadequate for severe disease.

Question 39Sleep-Related Breathing Disorders

Which finding on a diagnostic study suggests that a patient's OSA is primarily due to upper airway obstruction rather than central causes?

  1. Absent effort with no thoracoabdominal movement
  2. Cheyne-Stokes respiration
  3. Ongoing effort with paradoxical thoracoabdominal motion Correct answer.
  4. Periodic breathing with crescendo-decrescendo pattern

Explanation

Paradoxical thoracoabdominal motion with continued effort reflects obstruction against a closed airway. Absent effort and periodic breathing patterns point toward central mechanisms.

Question 40Sleep-Related Breathing Disorders

What is the primary purpose of a CPAP titration study?

  1. To measure daytime sleepiness objectively
  2. To assess cardiac arrhythmias
  3. To determine the pressure that eliminates respiratory events across sleep stages and positions Correct answer.
  4. To diagnose restless legs syndrome

Explanation

Titration identifies the pressure that abolishes apneas, hypopneas, and desaturations in all sleep stages and positions. It is not a diagnostic test for other sleep disorders.

Question 41Sleep-Related Breathing Disorders

Which statement about oral appliance therapy for OSA is most accurate?

  1. It is contraindicated in all patients with mild OSA
  2. It is equally effective as CPAP for severe OSA
  3. It works by increasing central respiratory drive
  4. It advances the mandible to enlarge the upper airway Correct answer.

Explanation

Mandibular advancement devices reposition the mandible and tongue anteriorly, enlarging the pharyngeal airway. They are generally less effective than CPAP in severe disease but useful in mild-to-moderate OSA or CPAP intolerance.

Question 42Sleep-Related Breathing Disorders

A patient with OSA has a BMI of 38 and reports morning headaches and daytime somnolence. Which additional evaluation is most important?

  1. Assessment for insomnia
  2. Assessment for awake hypercapnia Correct answer.
  3. Assessment for restless legs syndrome
  4. Assessment for narcolepsy

Explanation

Morning headaches and somnolence in a patient with obesity raise concern for obesity hypoventilation syndrome. Measurement of awake arterial blood gases or bicarbonate helps identify hypercapnia.

Question 43Sleep-Related Breathing Disorders

Which mechanism best explains the increased OSA severity in patients with hypothyroidism?

  1. Increased pharyngeal dilator tone
  2. Reduced circulating blood volume
  3. Deposition of mucopolysaccharides in upper airway tissues and reduced ventilatory drive Correct answer.
  4. Enhanced chemoreceptor sensitivity

Explanation

Hypothyroidism can cause myxedematous infiltration of upper airway structures and depress ventilatory drive, worsening obstruction and hypoventilation. Treatment of hypothyroidism may improve but does not always resolve OSA.

Question 44Sleep-Related Breathing Disorders

Which finding on a polysomnogram is most consistent with a mixed apnea?

  1. Absent effort initially followed by resumption of effort without airflow Correct answer.
  2. Normal airflow with paradoxical effort
  3. Continued effort throughout the event
  4. Absent effort throughout the event

Explanation

A mixed apnea begins as a central event with absent effort and transitions to an obstructive component with effort but no airflow. This combination distinguishes it from pure central or obstructive events.

Question 45Sleep-Related Breathing Disorders

A patient on adaptive servo-ventilation for central sleep apnea has worsening symptoms and a history of severe heart failure with reduced ejection fraction. What is the most important consideration?

  1. The device should be switched to fixed CPAP without review
  2. Adaptive servo-ventilation may increase mortality in heart failure with reduced ejection fraction and should be reassessed Correct answer.
  3. Central apnea in heart failure never requires treatment
  4. Adaptive servo-ventilation is always first-line in this population

Explanation

A large trial showed increased mortality with adaptive servo-ventilation in patients with central sleep apnea and heart failure with reduced ejection fraction. Therapy should be reassessed and individualized.

Question 46Sleep-Related Breathing Disorders

Which nocturnal oximetry pattern most strongly suggests obstructive sleep apnea rather than a purely central breathing pattern?

  1. Sawtooth desaturations that terminate with an abrupt rise in oxygen saturation Correct answer.
  2. A single prolonged desaturation lasting most of the night
  3. Cyclic gradual desaturations with a crescendo-decrescendo ventilatory pattern
  4. Stable saturation with occasional isolated dips during REM only

Explanation

Obstructive events typically produce repetitive desaturations that recover abruptly once the airway reopens after an arousal, giving a sawtooth appearance. Central patterns such as Cheyne-Stokes breathing show a gradual crescendo-decrescendo oscillation of breathing and oxygen. A single prolonged desaturation suggests sustained hypoventilation rather than discrete obstructive events.

Question 47Sleep-Related Breathing Disorders

Which measure on a diagnostic polysomnogram is used to define hypopnea when the AASM recommended rule is applied?

  1. A 30% or greater drop in airflow lasting at least 10 seconds with a 3% or greater oxygen desaturation or an arousal Correct answer.
  2. Any visible reduction in airflow lasting at least 5 seconds with snoring
  3. A 50% or greater drop in airflow lasting at least 30 seconds with no desaturation requirement
  4. A complete cessation of airflow lasting at least 10 seconds with continued effort

Explanation

The recommended AASM hypopnea rule requires a reduction in nasal pressure signal excursion of at least 30% from baseline lasting at least 10 seconds, accompanied by a 3% or greater desaturation or an arousal. The alternative acceptable rule uses a 4% desaturation without an arousal criterion. Complete cessation of airflow describes an apnea, not a hypopnea.

Question 48Sleep-Related Breathing Disorders

A 55-year-old man with treated hypertension and a BMI of 33 reports loud snoring and witnessed apneas. He has no daytime sleepiness and no other comorbidities. Which study is most appropriate to establish the diagnosis?

  1. Attended in-laboratory polysomnography
  2. Home sleep apnea test with a type 3 device Correct answer.
  3. Multiple sleep latency test
  4. Overnight pulse oximetry alone

Explanation

A home sleep apnea test is appropriate when there is a high pretest probability of moderate to severe OSA in an adult without significant cardiopulmonary disease, neuromuscular disease, or other sleep disorders. The absence of daytime sleepiness does not by itself mandate in-laboratory testing. Pulse oximetry alone is not diagnostic, and the MSLT assesses daytime sleepiness rather than breathing events.

Question 49Sleep-Related Breathing Disorders

A patient with severe OSA and chronic obstructive pulmonary disease is started on bilevel positive airway pressure with a backup rate because of chronic hypercapnia. Which parameter most directly determines the added minute ventilation from the backup rate?

  1. The difference between inspiratory and expiratory pressure
  2. The inspiratory positive airway pressure
  3. The expiratory positive airway pressure
  4. The backup respiratory rate Correct answer.

Explanation

When a backup rate is set, the device delivers a minimum number of breaths per minute, and that rate largely governs the guaranteed minute ventilation in the absence of spontaneous effort. The pressure difference (inspiratory minus expiratory pressure) determines tidal volume per delivered breath. Together, rate and tidal volume set minute ventilation, but the backup rate is the parameter that ensures a minimum breathing frequency.

Question 50Sleep-Related Breathing Disorders

A 62-year-old man with treated OSA on CPAP develops recurrent apneas with a Cheyne-Stokes pattern and an ejection fraction of 30%. His clinician is considering adaptive servo-ventilation but recalls a major trial result. Which statement best reflects the evidence regarding adaptive servo-ventilation in this population?

  1. It improves exercise tolerance without affecting mortality
  2. It is equivalent to CPAP for all outcomes in heart failure
  3. It increases all-cause and cardiovascular mortality in patients with central sleep apnea and reduced ejection fraction Correct answer.
  4. It is contraindicated in all forms of central sleep apnea

Explanation

The SERVE-HF trial found increased all-cause and cardiovascular mortality with adaptive servo-ventilation in patients who had predominantly central sleep apnea and a reduced left ventricular ejection fraction. As a result, ASV is not recommended in that specific group. It remains an option for central sleep apnea in patients with preserved ejection fraction or other selected contexts.