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Flashcards in 42 Sleep Disordered Breathing Deck (23)
1

Obstructive sleep disordered breathing

  • An obstructive apnea (OSA)
  • An obstructive hypopnea 
  • A variety of methods are available to measure...
    • Airflow cessation (apnea) 
    • Limitation (hypopnea) during sleep
  • The accuracy of measuring airflow limitation can be substantially influenced by...

  • An obstructive apnea (OSA)
    • The lack of airflow measured at the nose and mouth for 10 seconds or longer during sleep despite ongoing effort to breathe
    • Usually associated with a decrease in the oxyhemoglobin saturation and a change in the electroencephalogram (EEG) indicating arousal from sleep
  • An obstructive hypopnea
    • A decrease in airflow (generally > 30%) at the nose and mouth despite ongoing effort to breathe
    • Associated with a decrease in the oxyhemoglobin saturation and a change in the EEG indicating arousal from sleep
  • A variety of methods are available to measure...
    • Airflow cessation (apnea)
      • Apneas in adults are easily identified even with simple monitoring devices such as thermal sensors (thermisters or thermocouples)
    • Limitation (hypopnea) during sleep
      • This is not the case for airflow limitation (i.e. hypopnea)
  • The accuracy of measuring airflow limitation can be substantially influenced by...
    • The method of measurement

2

Obstructive sleep disordered breathing

  • On polysomnography (PSG), both apneas and hypopneas are commonly associated with...
  • In current clinical practice, hypopneas that are accepted as physiologically significant events
  • Apnea / hypopnea index (AHI) to rate syndrome severity
    • Mild OSAH
    • Moderate OSAH 
    • Severe OSAH 
  • Other metrics of sleep apnea 

  • On polysomnography (PSG), both apneas and hypopneas are commonly associated with...
    • Changes on the EEG as a marker of sleep disruption
    • However, the intra- and inter-rater reliability of visually scoring arousals is variable
  • In current clinical practice, hypopneas that are accepted as physiologically significant events
    • > 4 % desaturations, without arousal criteria
  • Apnea / hypopnea index (AHI) to rate syndrome severity
    • Mild OSAH
      • An AHI between 5 and 15 events per hour of sleep
    • Moderate OSAH
      • An AHI of 15 to 30 events per hour of sleep
    • Severe OSAH
      • An AHI of greater than 30 events per hour of sleep
  • Other metrics of sleep apnea
    • Symptoms related to disrupted sleep
    • The degree and severity of oxygen desaturation
    • The presence of concomitant cardiovascular conditions that might be adversely impacted by sleep apnea

3

Epidemiology

  • In predominately Caucasian middle-aged cohorts, the prevalence of OSAH...
  • Gender
  • The prevalence of OSAH in middle aged individuals 
  • Menopause and obesity
  • Race
  • What contributes relatively more to OSAH occurrence than obesity in African Americans
  • Advancing age and increasing weight 
  • Age

  • In predominately Caucasian middle-aged cohorts, the prevalence of OSAH...
    • Defined as AHI > 10 plus symptoms of daytime sleepiness and / or hypertension
    • ~5%
  • Gender
    • Increased risk in men, with a prevalence of 3.3:1 compared to women
  • The prevalence of OSAH in middle aged individuals
    • 4% for men and 2% for women
  • Menopause and obesity
    • Increase the risk of OSAH
  • Race
    • The prevalence of OSAH is higher in African Americans as opposed to the Caucasians
  • What contributes relatively more to OSAH occurrence than obesity in African Americans
    • Facial structure
  • Advancing age and increasing weight
    • Independently increase the risk of OSAH
  • Age
    • The age effect appears to plateau after age 65
    • There may be an increase in mortality in middle age or possibly remission of OSAH in the elderly population

4

Pathophysiology

  • The upper airway in humans is able to perform a variety of complex functions,
    including...
  • This is possible in part, because of...
  • What may cause narrowing (hypopnea) or closure (apnea)
  • What produces snoring sounds
  • The primary cause for airway closure during sleep
  • Major determinants of a small airway in adults
  • Individuals with OSAH: awake vs. asleep
  • The uniform stimulus for resumption of normal breathing 

  • The upper airway in humans is able to perform a variety of complex functions,
    including...
    • Breathing, swallowing, and speaking
  • This is possible in part, because of...
    • The lack of rigid support from bone or cartilaginous tissue in the retro-palatal and retro-lingual airway
  • What may cause narrowing (hypopnea) or closure (apnea)
    • When increased negative intrathoracic pressure results in a suction force applied to a small, compliant, upper airway
  • What produces snoring sounds
    • The vibration of the narrowed airway
  • The primary cause for airway closure during sleep
    • A small airway
  • Major determinants of a small airway in adults
    • Craniofacial structure and function, in addition to obesity
  • Individuals with OSAH: awake vs. asleep
    • Able to maintain airway patency during wakefulness
    • When transition occurs from wake to the sleeping state, muscle tone decreases and snoring, airway narrowing and /or closure may occur in individuals with a “vulnerable airway”
  • The uniform stimulus for resumption of normal breathing
    • A ventilatory related arousal from sleep
    • The arousal can usually be identified on the EEG channel when sleep and breathing are measured in the laboratory
    • The ventilatory related arousal may be precipitated by increased airway resistance (usually associated with snoring), hypopnea, or apnea

5

Pathophysiology:
Other important physiologic perturbations occur in conjunction with the sleep disordered breathing events

  • Struggling against a partially or completely closed airway is associated with...
  • The ensuing arousal is accompanied by...
  • These phenomena have acute and chronic effects on...
  • Intermittent hypoxemia 
  • The ischemia-reperfusion associated with intermittent hypoxemia results in...
  • A number of bio-markers that have been linked to risk and progression of cardiovascular disease in addition to altered metabolic function

  • Struggling against a partially or completely closed airway is associated with...
    • Increased intrathoracic pressure, hypoventilation, and increased vagal tone
  • The ensuing arousal is accompanied by...
    • Augmentation of sympathetic tone
  • These phenomena have acute and chronic effects on cardiovascular function
    • Acute changes are manifest as bradycardia followed by tachycardia (i.e. heart rate variability)
    • Over time, sympathetic tone is upregulated not only nocturnally but also diurnally
  • Intermittent hypoxemia
    • A hallmark of OSAH
  • The ischemia-reperfusion associated with intermittent hypoxemia results in...
    • Transcription and translation of bio-markers of oxidative stress and subsequent endothelial dysfunction
  • A number of bio-markers that have been linked to risk and progression of cardiovascular disease in addition to altered metabolic function
    • C-reactive protein and Interleukin 6

6

Consequences:
OSAH is associated with significant co-morbidities that are the result of the altered nocturnal physiology

  • These co-morbidities can be broadly grouped into three categories 
  • These co-morbidities appear to have...
  • Adequate treatment of OSAH

  • These co-morbidities can be broadly grouped into three categories
    • Cardiovascular
    • Metabolic
    • Neurocognitive 
  • These co-morbidities appear to have...
    • A dose response effect with regard to the severity of OSAH
  • Adequate treatment of OSAH
    • Primarily with positive pressure
    • Favorably impacts these co-morbidities

7

Cardiovascular complications

  • The normal cardiovascular response to sleep
  • Acute and chronic physiological effects related to sleep disordered breathing
  • Risk is increased for...
  • A link between the AHI and cardiovascular complications
  • Relationship between apnea and hypopnea and incident hypertension

  • The normal cardiovascular response to sleep
    • Includes a physiologic decrease in blood pressure and heart rate
    • Negatively impacted in OSAH
  • Acute and chronic physiological effects related to sleep disordered breathing
    • The repetitive bursts of sympathetic activity triggered by the sleep disordered breathing events adversely affect nocturnal blood pressure and heart rate
    • Over time, a profound toll is taken on the cardiovascular system
  • Risk is increased for...
    • Diurnal systemic hypertension, diurnal pulmonary hypertension, atrial dysrhythmias, heart failure (systolic and diastolic), myocardial infarction, and stroke
  • A link between the AHI and cardiovascular complications
    • The best evidence exists for diurnal systemic hypertension
  • Relationship between apnea and hypopnea and incident hypertension
    • After controlling for known confounding risk factors for the development of hypertension (smoking, alcohol weight, age, and sex), a dose response relationship exists

8

Metabolic complications

  • Relationship between AHI and bio-markers of the metabolic syndrome
  • This relationship persists after controlling for...
  • Leptin
  • Obesity and leptin

  • Relationship between AHI and bio-markers of the metabolic syndrome
    • Dose response relationship between the AHI and bio-markers of the metabolic syndrome (serum glucose and insulin sensitivity)
  • This relationship persists after controlling for...
    • Concomitant obesity
  • Leptin
    • An adipokine that appears to play an important role in metabolic and ventilatory control
    • Elevated in OSAH
    • Inhibits the synthesis of neuropeptide Y, a potent stimulator of food intake
  • Obesity and leptin
    • Obese individuals typically have elevated circulating leptin levels suggesting leptin resistance
    • The elevated leptin levels are not explained by obesity alone
    • Leptin levels in patients with OSAH are elevated compared to matched obese controls, suggesting a direct effect of sleep disordered breathing

9

Neurocognitive complications

  • Daytime sleepiness
  • Severity of sleep disordered breathing vs. daytime sleepiness
  • The severity of OSAH also correlates with...

  • Daytime sleepiness
    • One of the defining features of the OSAH syndrome
  • Severity of sleep disordered breathing vs. daytime sleepiness
    • There is a dose response relationship between the severity of sleep disordered breathing and the complaint of daytime sleepiness
  • The severity of OSAH also correlates with...
    • The risk of motor vehicle and occupational accidents
    • After adjusting for a number of confounding variables to include body-mass index, alcohol consumption, eyesight, medications, driving experience, and sleep schedule, subjects with a AHI of > 10 had a 7.2 odds ratio for having a traffic accident
    • The risk for occupational accidents in sleepy snorers was 2.2 times that of the control population

10

Neurocognitive complications

  • Untreated OSAH was associated with...
    • Significant impact on...
    • Negligible impact on...
    • Questionable association between...
  • Sleepiness and impaired cognitive function undoubtedly...

  • Untreated OSAH was associated with...
    • Significant impact on vigilance, executive functioning, and coordination
    • Negligible impact on intellectual and verbal functioning
    • Questionable association between depression and OSAH
  • Sleepiness and impaired cognitive function undoubtedly impact on quality of life

11

Clinical presentation:
Findings on the history and physical associated with the presence of OSA 

  • The signs and symptoms that suggest the diagnosis of OSAH
  • What may be present
  • What may place selected individuals at risk for airway closure during sleep
  • Signs that may be associated with occult OSAH

  • The signs and symptoms that suggest the diagnosis of OSAH
    • Nightly loud snoring
    • Breathing pauses during sleep
    • Snorting
    • Choking
    • Subjective daytime sleepiness
  • What may be present
    • Obesity (particularly upper body obesity)
    • Systemic hypertension
  • What may place selected individuals at risk for airway closure during sleep
    • Craniofacial abnormalities (retro or micrognathia)
    • Soft tissue abnormalities, such as...
      • Enlarged tonsils
      • Lateral narrowing of the airway
      • An elongated soft palate
  • Signs that may be associated with occult OSAH
    • Right sided heart failure in the absence of established heart disease

12

Laboratory testing

  • Standard for confirming a diagnosis of OSAH in the US
  • Sleep stages 
  • Sleep is analyzed by measuring...
  • Cardiopulmonary parameters are measured, including...
  • Sensors are applied to the legs in order to identify...
  • Less intensive (and less expensive) alternatives to laboratory polysomnography 

  • Standard for confirming a diagnosis of OSAH in the US
    • Objective measurement and quantification of sleep and breathing in a sleep laboratory
  • Sleep stages
    • Identified in addition to the degree of sleep disruption that is due to sleep disordered breathing events
  • Sleep is analyzed by measuring...
    • Electoroencephalographic (via a central lead)
    • Bilateral electrooculographic
    • Submental electromyographic (chin) activity
  • Cardiopulmonary parameters are measured, including...
    • Airflow, breathing effort, oximetry, and electrocardiogram
  • Sensors are applied to the legs in order to identify...
    • Periodic leg movements that may be responsible for disrupting sleep
  • Less intensive (and less expensive) alternatives to laboratory polysomnography 
    • Accurate at diagnosing OSAH in patients with a moderate or high pre-test probability for the disease
    • These portable monitor studies include single (or multiple) night continuous measurement of one or more cardiopulmonary parameters, generally pulse oximetry, heart rate, nasal airflow and / or respiratory effort
    • Home sleep tests do not actually measure sleep

13

Lifestyle interventions

  • Relevant lifestyle interventions 
  • Weight loss
  • Alcohol and sedatives 
  • Positioning

  • Relevant lifestyle interventions
    • Positive pressure administered via a mask remains the initial treatment of choice
    • Second line therapy can involve oral appliance therapy and, in selected patients, upper airway surgery
  • Weight loss
    • Obesity is a major risk factor for OSAH
    • Weight loss has been demonstrated to improve both sleep and breathing
    • Avoiding sleep deprivation will not only decrease daytime sleepiness related to sleep debt but also increase upper airway muscle tone
  • Alcohol and sedatives
    • Also negatively affect upper airway muscle tone
    • The magnitude of the impact of sedatives on the unstable upper airway is not well defined
  • Positioning
    • If the patient has clearly has positional OSAH, lateral positioning or head of bed elevation may be helpful

14

Positive pressure therapy

  • Reliably treats...
  • Works primarily by...
  • When a proper positive pressure prescription is performed...
  • Can be applied as...
  • Positive pressure therapy (primarily CPAP) 
    • Has a favorable effect on...
    • CPAP improves...

  • Reliably treats airway closure during sleep
  • Works primarily by “pneumatically splinting” the airway open during sleep
  • When a proper positive pressure prescription is performed, the treatment effect is virtually immediate
  • Can be applied as...
    • Continuous positive airway pressure (CPAP) 
    • Bi-level positive airway pressure (BPAP)
      • The pressure setting during inspiration is higher than expiration, taking advantage of the fact that during inspiration the airway pressure is more negative than during expiration
      • This is accomplished by the machine sensing changes in airflow associated with breathing
    • Both CPAP and BPAP machines are electrically operated and are highly portable, usually weighing less than 10 pounds
  • Positive pressure therapy (primarily CPAP)
    • Has a favorable effect on quality of life, objective daytime function, and blood pressure
    • CPAP improves insulin sensitivity, left ventricular function, pulmonary hypertension, endothelial function, and cardiovascular and overall mortality

15

Positive pressure therapy

  • Despite its effectiveness, objective adherence to therapy is similar to...
  • Acceptance and adherence to positive pressure can be improved with...
  • In general, CPAP or BPAP is delivered via...
  • Patients with OSAH frequently report symptoms of...
  • When the mouth opens, the machine...
  • Heated humidifiers in-line with the CPAP/BPAP unit can frequently...
  • What can occasionally be helpful
  • What can be helpful in patients who are claustrophobic

  • Despite its effectiveness, objective adherence to therapy is similar to...
    • Most medical regimens at approximately 50% without structured educational interventions
  • Acceptance and adherence to positive pressure can be improved with...
    • Patient education
    • Appropriate attention to patient – machine related problems
  • In general, CPAP or BPAP is delivered via...
    • A nasal interface
    • Proper fit is essential
    • Nasal congestion and / or dryness need to be treated
  • Patients with OSAH frequently report symptoms of...
    • Nasal congestion prior to treatment
    • This problem can be exacerbated by positive pressure therapy
    • The airflow through the nose at flow rates of 30 to 60 liters per minute (depending on the seal) can be drying to nasal mucosa
    • This frequently triggers rebound nasal congestion that precipitates mouth breathing
  • When the mouth opens, the machine...
    • Increases the flow to maintain the set pressure exacerbating the congestion
  • Heated humidifiers in-line with the CPAP/BPAP unit can frequently...
    • Improve the nasal dryness and subsequent congestion
  • What can occasionally be helpful
    • A mask that covers both the nose and mouth
  • What can be helpful in patients who are claustrophobic
    • Desensitization

16

Oral appliance therapy

  • The goal of oral appliance therapy (OAP) 
  • Second line therapy for OSAH because...
  • Effectiveness of OAP 
  • When compared to positive pressure, patients frequently prefer...

  • The goal of oral appliance therapy (OAP)
    • To modify the position of the mandible and the tongue in order to increase the upper airway size and favorably affect collapsibility
  • Second line therapy for OSAH because...
    • Effective treatment requires multiple adjustments that require weeks to months to accomplish
    • Treatment is not 100% effective
    • Objective adherence cannot be measured
  • Effectiveness of OAP
    • Subjective sleepiness and sleep disordered breathing are favorably impacted
    • There's a favorable effect on blood pressure
  • When compared to positive pressure, patients frequently prefer...
    • OAP to CPAP/BPAP

17

Oral appliance therapy

  • Tongue retaining devices (TRD) 
    • Mechanism
    • Can be used in...
    • Many patients are bothered by...
  • Mandibular advancement devices (MAD)
    • Pros
    • Cons
    • Optimal therapy is achieved...
    • Patients who respond best

  • Tongue retaining devices (TRD)
    • Apply suction to the anterior portion of the tongue to maintain tongue protrusion and increase in the retrolingual airway
      • A degree of downward rotation of the mandible is achieved
    • Can be used in edentulous patients
    • Many patients are bothered by the bulk of the TRDs, which negatively impacts adherance
  • Mandibular advancement devices (MAD)
    • Adjustable MADs are more comfortable and generally yield better results than nonadjustable “boil and bite” appliances
    • Sequential adjustment requires weeks to accomplish and as a result, limits the utility of MADs in severe OSAH that requires expeditious treatment
    • Optimal therapy is achieved in approximately one third of subjects
    • Patients who respond best are those with mild OSAH, supine-dependent OSAH, and snoring

18

Oral appliance therapy

  • Contraindications and complications associated with MAD treatment
  • Side effects 
  • Common side effects 
  • Other information about MADs

  • Contraindications and complications associated with MAD treatment
    • Insufficient tooth number
    • Substantial tooth mobility
    • Untreated periodontal disease
    • Active temporomandibular joint syndrome
  • Side effects
    • Usually mild and infrequently require intervention
  • Common side effects
    • Mucosal dryness
    • Tooth discomfort
    • Hypersalivation
  • Other information about MADs
    • MADs are known to change occlusion over time
    • Regular dental follow-up is mandatory in patients using these devices long term

19

Upper airway stimulation therapy

  • The onset of apnea and hypopneas is accompanied by...
  • Unilateral stimulation of the hypoglossal nerve has shown promise as...

  • The onset of apnea and hypopneas is accompanied by...
    • A reduction in neural drive to the upper airway muscles
  • Unilateral stimulation of the hypoglossal nerve has shown promise as...
    • A novel therapy for OSAH in highly selected patients
    • A nerve stimulator is implanted along the hypoglossal nerve to produce tongue protrusion
    • A sensing lead is implanted on the chest to detect respiratory effort
    • The patients turn on their upper airway “pacemaker” at bedtime and turn it off in the morning

20

Surgical therapy

  • Surgical therapy 
  • Palatal surgery alone
  • Surgery therapy can be broadly divided into two categories
  • Upper airway reconstruction for OSAH 

  • Surgical therapy
    • Has a small but definite role in the management of OSAH in adults
  • Palatal surgery alone
    • Useful in treating primary snoring
    • Rarely effective in treating OSAH
  • Surgery therapy can be broadly divided into two categories
    • Tracheostomy (bypass of the upper airway)
    • Reconstruction of the upper airway
  • Upper airway reconstruction for OSAH
    • An elective surgery that should be contemplated only after CPAP/BPAP have been tried
    • If there are cosmetic considerations such as retrognathia or micrognathia, particularly in a young adult, this treatment may make good sense

21

Surgical therapy

  • Tracheostomy 
  • Positive pressure therapy 
  • A small group of patients with severe and potentially life-threatening OSAH who are intolerant of CPAP/BPAP 
  • It is important to reassess the patient’s nocturnal oxygen saturation post-tracheostomy because...

  • Tracheostomy
    • The original treatment for OSAH
    • The appearance of the tracheostomy can result in psychological and social morbidity
    • The treatment is well tolerated and results in cure of OSAH
    • Local complications involving the tracheal stoma can occur within the first year post-tracheostomy
  • Positive pressure therapy 
    • Has largely replaced tracheostomy as the treatment of choice for severe OSAH
  • A small group of patients with severe and potentially life-threatening OSAH who are intolerant of CPAP/BPAP
    • Require trachesotomy
  • It is important to reassess the patient’s nocturnal oxygen saturation post-tracheostomy because...
    • The morbidly obese patient can still exhibit significant non-obstructive oxyhemoglobin desaturation in rapid eye movement sleep

22

Surgical therapy

  • Reconstruction of the upper airway 
  • In OSAH, airway closure occurs...
  • In order to effectively treat OSAH, one must consider...
  • A phased approach to upper airway reconstruction
    • Phase I surgery 
    • Phase II surgery 

  • Reconstruction of the upper airway
    • A better option from a cosmetic perspective 
    • Unfortunately is associated with less certain results
  • In OSAH, airway closure occurs...
    • At more than one site during sleep
  • In order to effectively treat OSAH, one must consider...
    • Airway closure involving the palate and the base of the tongue must be considered
  • A phased approach to upper airway reconstruction
    • Phase I surgery
      • Generally involves a palatoplasty and a genioglossal advancement procedure
      • Is associated with low morbidity but less than optimal results ranging from a success of 22% to 60% in the literature
    • Phase II surgery 
      • Involves maxillomandibular advancement
      • Is more effective with reported success rates ranging from 75% to 100%
      • Produce changes in occlusion that invariably require postoperative orthodontics

23

Conclusions

  • Obstructive sleep apnea 
  • Clinical clues that suggest the diagnosis of OSA
  • The diagnosis needs to be confirmed by...
  • Nasal CPAP
  • Selected patients who do not accept or adhere to nasal CPAP may benefit from...

  • Obstructive sleep apnea
    • A common clinical condition that is associated with significant metabolic, cardiovascular, and neurocognitive morbidity and mortality
  • Clinical clues that suggest the diagnosis of OSA
    • Heavy snoring, observed apnea, and daytime sleepiness
  • The diagnosis needs to be confirmed by...
    • An overnight sleep study either in the laboratory or a portable monitor at home
  • Nasal CPAP
    • The initial medical therapy of choice
    • Highly effective in patients with moderate to severe OSA and daytime sleepiness
    • Improve nocturnal cardiovascular function, daytime sleepiness, and quality of life are substantially improved
  • Selected patients who do not accept or adhere to nasal CPAP may benefit from...
    • OAP therapy or surgery
    • Long-term treatment can favorably impact cardiovascular outcomes

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