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Breathing abnormalities induced by sleep—ie, sleep disordered breathing (SDB)—is now recognized as a common condition with serious adverse consequences. “Sleep Apnea” is a term that refers to diminished breathing during sleep. It is a condition associated with a variety of factors and can be very significant to patients with chronic pain. There are two types of sleep apnea: “Central Sleep Apnea” and “Obstructive Sleep Apnea” as well as a combination of the two, termed “Mixed Sleep Apnea.”
Central Sleep Apnea (CSA)
“Central sleep apnea” (CSA) is diminished breathing during sleep that occurs due to reduced respiratory drive as a consequence of a central nervous system disorder, stroke, spinal cord injury or when medications suppress the brain’s drive to make one breathe. There are many medications that suppress the brain’s drive to breathe during sleep including opiates (pain medications like Lorcet, oxycodone, morphine and methadone), benzodiazepines (like Xanax, Valium and Klonopin), sedatives (sleeping pills) and many psychiatric medications (such as antidepressants) , muscle relaxers (especially Soma) and, most importantly, alcohol. It is this suppression of breathing associated with use of these medications and/or alcohol that is why overdosing with these medications causes death.
Obstructive Sleep Apnea (OSA)
The most common form of SDB is obstructive sleep apnea (OSA), diminished breathing during sleep related to airway obstruction that may result from nasal obstruction (such as with deviated nasal septums) and/or throat obstruction (generally manifested as snoring). When a person has significant airway obstruction during sleep, it results in reduced air flow and reduced oxygen in their blood. The increased airway resistance associated with airway obstruction leads to partial (hypopnea) or complete (apnea) upper airway collapse and is characterized by frequent breathing pauses due to sleep-related changes in muscle tone usually related to snoring.
Snoring generally becomes worse during the deep stages of sleep when muscles become most relaxed. When the oxygen levels drop, the brain signals the sleeper to arouse from their deep sleep to light sleep so that breathing becomes more effective and the oxygen levels increase again. After awhile, the person cycles from their light sleep back again to deep sleep until their oxygen levels drop again and they are driven back to light sleep. Deep sleep is necessary for the maintenancy of healthy brain function. When a person repeatedly is disrupted from their deep sleep and cycled back to light sleep (fragment sleep), they become sleep deprived with the consequences noted below.
Prevalence of Sleep Apnea
The estimated prevalence of OSA has increased substantially over the last two decades, most likely due to the obesity epidemic. It is now estimated by some that 26 percent of adults between the ages of 30 and 70 years have sleep apnea whereas other estimates indicate 3-7% in men and 2-5% in women in the general population have sleep apnea. The percentages are much higher (> 50%) in those people with cardiac or metabolic disorders such as obesity or diabetes. Combined with current estimates that 1 out of 5 North Americans suffers from chronic pain and 1 out of 5 of chronic pain patients take chronic opioids for their pain, the number of of people with sleep apnea and pain patients with sleep apnea is staggering. While the incidence of untreated sleep apnea is unknown, it is estimated that more than half the population with sleep apnea are either unaware and/or untreated for their sleep apnea.
Consequences of Untreated OSA
If a person has significant airway obstruction, this cycling back and forth between deep sleep to light sleep can occur literally hundreds of times during a night’s sleep. The end result is that the person never actually gets enough deep sleep. Deep sleep is the time during which we get the most benefits from sleep. Without enough deep sleep we do not feel well rested and we are considered sleep deprived. Those with sleep deprivation tend to suffer from fatigue, daytime drowniness, irritablility, depression, weight gain, increased risk for high blood pressure and diabetes and poor pain control. So it is important to identify those who have significant airway obstruction because it is treatable and those who get treatment will have more energy and less fatigue, better moods, and better pain control.
Those with untreated sleep apnea have double the risk of a work place accident and 15x the likelihood of being involved in a motor vehicle accident. A recent study found that people with severe, untreated sleep apnea had a significant reduction in white matter integrity in multiple brain areas, which was accompanied by impairments to cognition, mood and daytime alertness. One year of CPAP therapy (see below) led to an almost complete reversal of this brain damage.
Risk factors for OSA
People who experience excessive daytime sleepiness who fall asleep easily while sitting inactively, talking with someone or reading or watching TV are at greater risk of having sleep apnea. Risk factors for OSA include: loud snoring, observed periods when breathing stops momentarily during sleep, obesity (especially with BMI >35), males>females, thick necks and age >50 y/o. Other contributing risks include menopause, alcohol and cigarette use, craniofacial structure abnormalities and family history.
Sleep Apnea and Opioids
Identifying and treating sleep apnea in patients with chronic pain is especially important. First, patients with poor quality sleep as a result of their untreated sleep apnea will have greater difficulty tolerating their pain due to their increased fatigue and irritability. But, importantly, patients with chronic pain who take opiates and other medications that suppress breathing may worsen their sleep apnea, especially central sleep apnea and may be less responsive to the drop in oxygen associated with their sleep apnea. This can result in prolonged drops of oxygen resulting in a heart attack or simply not waking up. This is the mechanism believed to be a contributing factor to the recent increased incidence of accidental deaths related to increased use of prescription pain medications.
Who is at Risk with Opioids and When?
Unintentional deaths related to sleep apnea with opioids is likely to affect patients on steady doses of usual medications. They have developed tolerance to their medications and do not appear to be at high risk. However, if one takes extra doses of their medications, adds new medications that may suppress breathing or if they drink alcohol, they may tip into a dangerous situation. Or if their obstructive sleep apnea goes untreated and worsens, thay may get into a dangerous situation. This risk is most worrisome if a patient has surgery and takes more pain medications in their post-operative period.
It is evident that the higher the dose of opioids, the more likely, and the more severe central sleep apnea will occur. Studies are mixed but it is estimated that up to more than 46% of chronic opioid patients may have severe sleep apnea and 71% have moderate sleep apnea. Interestingly, a large study showed that chronic pain patients not taking opioids had a greater incidence of sleep apnea than those taking opioids. Furthermore, the presence of other medications frequently prescribed to chronic pain patients are also thought to potentially contribute to risk for sleep apnea. Most obvious are the benzodiazepines (Xanax, Valium, Klonopin etc.) which are well known to contribute to respiratory depression. Less obvious are the antidepressants, antipsychotics, muscle relaxers and possibly antihistamines as possible contributors to sleep apnea. Studies are needed.
Another risk variable in the case of opioids and sleep apnea may occur when a person undergoes a pain procedure or otherwise experiences an abrupt and significant reduction in pain. It is believed that the presence of pain provides stimulation of respiratory drive and sudden pain reduction can reduce respiratory drive to the point of placing a patient on a steady opioid regimen at risk for respiratory depression. For this reason, it is recommended that a patient reduce their usual opioid dosing, especially routine long-acting opioids, when experiencing a marked reduction in their pain after an interventional pain procedure such as an epidural steroid injection or nerve ablation.
Diagnosis of Sleep Apnea
Ultimately, the guidelines remain unclear as to who should be tested for sleep apnea – should it be based on apparent risk factors, suggestive symptoms or a combination of both? Each clinician will consider obtaining a sleep study on a patient based on their own experience and education. Should you have concerns about sleep apnea, please consult your physician.
Your physician can screen for patients at high risk for sleep apnea and can refer you for a sleep study, or polysomnogram (PSG) to determine if there is a problem. A PSG consists of monitoring various functions while a patient is asleep, usually in a sleep lab with a dedicated technician to perform the monitoring of heart rate and rhythm, oxygen levels, breathing rate and patterns and sleep positioning.
The PSG allows identification and classification of sleep-related apneas and hypopneas. An apnea is defined as the complete cessation of airflow for at least 10 seconds. Apneas are further classified as obstructive, central, or mixed based on whether effort to breathe is present during the event. A hypopnea is defined as a reduction in airflow that is followed by an arousal from sleep or a decrease in oxygen saturation. Commonly used definitions of a hypopnea require a 25% or 50% reduction in airflow associated either with a reduction in oxygen saturation or an arousal from sleep. Sleep apnea severity is typically assessed with the apnea–hypopnea index (AHI), which is the number of apneas and hypopneas per hour of sleep. Mild sleep apnea is commonly defined as 5-15 AHI events/hr, moderate to severe sleep apnea as 15-30 AHI/hr and severe sleep apnea as > 30 AHI/hr. The same classification of central apnea index (CAI) and severity is based on the number of central sleep apnea events/hr.
There is a growing trend to perform PSGs in the comfort of the home by providing test equipment for home use. A diagnostic PSG is simply a PSG performed to establish the presence or absence of sleep apnea. A “split study” PSG means the first part of the PSG is diagnostic, the second part of the PSG is a “titration study” in which upon establishing the presence of sleep apnea in the initial diagnostic study, a treatment protocol is evaluated. A split study generally must be performed in a sleep lab with trained personnel.
Treatment of Sleep Apnea
OSA can be treated with medications, sleep aids (including CPAP or BiPAP, which are pressurized breathing masks (nasal or full facial) are worn during sleep) or surgery, depending on the cause of the obstruction. CSA can be treated by reducing medications that depress respiration but likely will also require a form of pressurized respiration. A relatively new form of Treatment generally results in marked improvement in symptoms, including improved energy, better mood, reduced pain and reduced risk of accidental death. Adaptive Seroventilation (ASV) is another means of providing respiratory support for treating sleep apnea associated with congestive heart failure (CHF) or central sleep apnea associated with medications including opioids. ASV combines CPAP with variable pressures and can be a preferred treatment option. A sleep specialist should be consulted when treating sleep apnea.
Please discuss any concerns with your physician and seek further asssessment when advised.
Sleep Apnea – Overviews
- Sleep Apnea Summary – handout
- SLEEP-DISORDERED BREATHING: National Sleep Disorders Research Plan, 2003, NCSDR, NHLBI, NIH
- Burden of Sleep Apnea – Rationale, Design, and Major Findings of the Wisconsin Sleep Cohort Study – 2009
- The Epidemiology of Adult Obstructive Sleep Apnea – 2008
- Obstructive sleep apnea in adults: epidemiology, clinical presentation, and treatment options. – PubMed – NCBI
- Rising prevalence of sleep apnea in U.S. threatens public health – American Academy of Sleep Medicine (AASM)
Sleep Apnea – Opioids
- Sleep-Disordered Breathing and Chronic Opioid Therapy
- Medium Increased Risk for Central Sleep Apnea but Not Obstructive Sleep Apnea in Long-Term Opioid Users – A Systematic Review and Meta-Analysis – 2016 ML F.
- Sleep Apnea Methadone and Benzodiazepine Therapy
- Assessing Sleep in Opioid Dependence – A Comparison of Subjective Ratings, Sleep Diaries, and Home Polysomnography in Methadone Maintenance Patients
- Obstructive Sleep Apnea is More Common than Central Sleep Apnea in Methadone Maintenance Patients with Subjective Sleep Complaints
- Drugs and Sleep Apneas A review of FPVD
- opioid-induced sleep apnea – is it a Real problem? – 2012
- Hypoxemia in patients on chronic opiate therapy with and without sleep apnea – 2008
- Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use – a comprehensive review – 2008
Sleep Apnea – Atypical Antipsychotics (Seroquel, Risperdal, Zyprexa, Clozaril)
- The impact of atypical antipsychotic use on obstructive sleep apnea – A pilot study and literature review
Sleep Apnea – Panic Disorder
Sleep Apnea – Treatment
Emphasis on Education
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