Obstructive Sleep Apnea and Chronic Opioid Use

Opioids, sleep, analgesia and respiratory depression: Their convergence on Mu (μ)-opioid receptors in the parabrachial area

Opioids provide analgesia, as well as modulate sleep and respiration, all by possibly acting on the μ-opioid receptors (MOR). MOR's are ubiquitously present throughout the brain, posing a challenge for understanding the precise anatomical substrates that mediate opioid induced respiratory depression (OIRD) that ultimately kills most users. Sleep is a major modulator not only of pain perception, but also for changing the efficacy of opioids as analgesics. Therefore, sleep disturbances are major risk factors for developing opioid overuse, withdrawal, poor treatment response for pain, and addiction relapse. Despite challenges to resolve the neural substrates of respiratory malfunctions during opioid overdose, two main areas, the pre-Bötzinger complex (preBötC) in the medulla and the parabrachial (PB) complex have been implicated in regulating respiratory depression. More recent studies suggest that it is mediation by the PB that causes OIRD. The PB also act as a major node in the upper brain stem that not only receives input from the chemosensory areas in medulla, but also receives nociceptive information from spinal cord. We have previously shown that the PB neurons play an important role in mediating arousal from sleep in response to hypercapnia by its projections to the forebrain arousal centers, and it may also act as a major relay for the pain stimuli. However, due to heterogeneity of cells in the PB, their precise roles in regulating, sleep, analgesia, and respiratory depression, needs addressing. This review sheds light on interactions between sleep and pain, along with dissecting the elements that adversely affects respiration.

Chronic Opioid Use and Sleep Disorders

Opioid medications are considered a significant component in the multidisciplinary management of chronic pain. In the past two decades, the use of opioid medications has dramatically risen in part because of an increased awareness by health care providers to treat chronic pain more effectively. In addition, patients are encouraged to seek treatment. The release of a sentinel joint statement in 1997 by the American Academy of Pain Medicine and the American Pain Society in a national effort to increase awareness and support the treatment of chronic pain has undoubtedly contributed to the opioid crisis.

OSA and Chronic Respiratory Disease: Mechanisms and Epidemiology

Obstructive sleep apnea (OSA) is a highly prevalent disorder that has profound implications on the outcomes of patients with chronic lung disease. The hallmark of OSA is a collapse of the oropharynx resulting in a transient reduction in airflow, large intrathoracic pressure swings, and intermittent hypoxia and hypercapnia. The subsequent cytokine-mediated inflammatory cascade, coupled with tractional lung injury, damages the lungs and may worsen several conditions, including chronic obstructive pulmonary disease, asthma, interstitial lung disease, and pulmonary hypertension. Further complicating this is the sleep fragmentation and deterioration of sleep quality that occurs because of OSA, which can compound the fatigue and physical exhaustion often experienced by patients due to their chronic lung disease. For patients with many pulmonary disorders, the available evidence suggests that the prompt recognition and treatment of sleep-disordered breathing improves their quality of life and may also alter the course of their illness. However, more robust studies are needed to truly understand this relationship and the impacts of confounding comorbidities such as obesity and gastroesophageal reflux disease. Clinicians taking care of patients with chronic pulmonary disease should screen and treat patients for OSA, given the complex bidirectional relationship OSA has with chronic lung disease.

Opioids and obstructive sleep apnea

Opioids are widely prescribed for pain management, and it is estimated that 40% of adults in the United States use prescription opioids every year. Opioid misuse leads to high mortality, with respiratory depression as the main cause of death. Animal and human studies indicate that opioid use may lead to sleep-disordered breathing. Opioids affect control of breathing and impair upper airway function, causing central apneas, upper airway obstruction, and hypoxemia during sleep. The presence of obstructive sleep apnea (OSA) increases the risk of opioid-induced respiratory depression. However, even if the relationship between opioids and central sleep apnea is firmly established, the question of whether opioids can aggravate OSA remains unanswered. While several reports have shown a high prevalence of OSA and nocturnal hypoxemia in patients receiving a high dose of opioids, other studies did not find a correlation between opioid use and obstructive events. These differences can be attributed to considerable interindividual variability, divergent effects of opioids on different phenotypic traits of OSA, and wide-ranging methodology. This review will discuss mechanistic insights into the effects of opioids on the upper airway and hypoglossal motor activity and the association of opioid use and obstructive sleep apnea.

CITATION

Freire C, Sennes LU, Polotsky VY. Opioids and obstructive sleep apnea. J Clin Sleep Med. 2022;18(2):647-652.

Chronic Opioid Use and Central Sleep Apnea, Where Are We Now and Where To Go? A State of the Art Review

Opioids are commonly used for pain management, perioperative procedures, and addiction treatment. There is a current opioid epidemic in North America that is paralleled by a marked increase in related deaths. Since 2000, chronic opioid users have been recognized to have significant central sleep apnea (CSA). After heart failure-related Cheyne-Stokes breathing (CSB), opioid-induced CSA is now the second most commonly seen CSA. It occurs in around 24% of chronic opioid users, typically after opioids have been used for more than 2 months, and usually corresponds in magnitude to opioid dose/plasma concentration. Opioid-induced CSA events often mix with episodes of ataxic breathing. The pathophysiology of opioid-induced CSA is based on dysfunction in respiratory rhythm generation and ventilatory chemoreflexes. Opioids have a paradoxical effect on different brain regions, which result in irregular respiratory rhythm. Regarding ventilatory chemoreflexes, chronic opioid use induces hypoxia that appears to stimulate an augmented hypoxic ventilatory response (high loop gain) and cause a narrow CO2 reserve, a combination that promotes respiratory instability. To date, no direct evidence has shown any major clinical consequence from CSA in chronic opioid users. A line of evidence suggested increased morbidity and mortality in overall chronic opioid users. CSA in chronic opioid users is likely to be a compensatory mechanism to avoid opioid injury and is potentially beneficial. The current treatments of CSA in chronic opioid users mainly focus on continuous positive airway pressure (CPAP) and adaptive servo-ventilation (ASV) or adding oxygen. ASV is more effective in reducing CSA events than CPAP. However, a recent ASV trial suggested an increased all-cause and cardiovascular mortality with the removal of CSA/CSB in cardiac failure patients. A major reason could be counteracting of a compensatory mechanism. No similar trial has been conducted for chronic opioid-related CSA. Future studies should focus on (1) investigating the phenotypes and genotypes of opioid-induced CSA that may have different clinical outcomes; (2) determining if CSA in chronic opioid users is beneficial or detrimental; and (3) assessing clinical consequences on different treatment options on opioid-induced CSA.

Opioids and sleep

PURPOSE OF REVIEW

Summarize the effects of opioids on sleep including sleep architecture, sleep disordered breathing (SDB) and restless legs syndrome.

RECENT FINDINGS

Opioids are associated with the development of central sleep apnea (CSA) and ataxic breathing. Recent reports suggest that adaptive servo-ventilation may be an effective treatment for CSA associated with opioids.

SUMMARY

Opioids have multiple effects on sleep, sleep architecture and SDB. Although originally described with methadone use, most commonly used opioids have also been shown to affect sleep. In patients on chronic methadone, sleep architecture changes include decreases in N3 and REM sleep. However, in patients with chronic nonmalignant pain, opioids improve sleep quality and sleep time. Opioids, generally at a morphine equivalent dose more than 100 mg/day, are associated with an increased incidence of CSA and ataxic breathing as well as obstructive sleep apnea. Other risk factors may include concomitant use of other medications such as antidepressants, gabapentinoids and benzodiazepines. Opioid-induced CSA can be potentially treated with adaptive servo-ventilation. Finally, opioids are a potential therapeutic option for restless legs syndrome unresponsive to dopamine agonists and other medications. However, use in patients with restless legs syndrome should proceed with caution, taking into account the risk for dependence and development of SDB.

The relationship between opioid use and obstructive sleep apnea: A systematic review and meta-analysis

We conducted a systematic review to address limited evidence suggesting that opioids may induce or aggravate obstructive sleep apnea (OSA). All clinical trials or observational studies on adults from 1946 to 2018 found through MEDLINE, EMBASE, CINAHL, PsycINFO, Cochrane Databases were eligible. We assessed the quality of the studies using published guidelines. Fifteen studies (six clinical trials and nine observational) with only two of good quality were included. Fourteen studies investigated the impact of opioids on the presence or severity of OSA, four addressed the effects of treatment for OSA  in opioid users, and none explored the consequences of opioid use in individuals with OSA. Eight of 14 studies found no significant relationship between opioid use or dose and apnea-hypopnea index (AHI) or degree of nocturnal desaturation. A random-effects meta-analysis (n = 10) determined the pooled mean change in AHI associated with opioid use of 1.47/h (-2.63-5.57; I² = 65%). Three of the four studies found that continuous positive airway pressure (CPAP) therapy reduced AHI by 17-30/h in opioid users with OSA. Bilevel therapy with a back-up rate and adaptive servo-ventilation (ASV) without mandatory pressure support successfully normalized AHI (≤5) in opioid users. Limited by a paucity of good-quality studies, our review did not show a significant relationship between opioid use and the severity of OSA. There was some evidence that CPAP, Bilevel therapy, and ASV alleviate OSA for opioid users, with higher failure rates observed in patients on CPAP in opioid users.

Chronic non-cancer pain and its association with healthcare use and costs among individuals with obstructive sleep apnea

Aim: To evaluate the impact of chronic non-cancer pain (CNCP) on healthcare use and costs among individuals diagnosed with obstructive sleep apnea (OSA). Materials & methods: Using the IQVIA PharMetrics^® Plus database, we identified individuals (18-64 years old) during 2007-2014, divided into two groups: OSA + CNCP versus OSA-only. Generalized linear models were used to analyze binary and count outcomes. Results: Relative to OSA-only controls, OSA + CNCP cases had increased odds for inpatient and emergency department visits and higher rates for physician office visits, non-physician outpatient visits, and prescription drug fills. Relative to controls, direct healthcare costs for cases were higher, primarily driven by inpatient and non-physician outpatient visit costs. Conclusion: Relative to OSA-only controls, OSA + CNCP cases displayed increased healthcare use and costs across all points of service.

Sleep-disordered breathing in patients on opioids for chronic pain

The past two decades has seen a substantial rise in the use of opioids for chronic pain, along with opioid-related mortality and adverse effects. A contributor to opioid-associated mortality is the high prevalence of moderate/severe sleep-disordered breathing, including central sleep apnea and obstructive sleep apnea, in patients with chronic pain. Although evidence-based treatments are available for sleep-disordered breathing, patients are not frequently assessed for sleep-disordered breathing in pain clinics. To aid healthcare providers in this area of clinical uncertainty, we present evidence on the interaction between opioids and sleep-disordered breathing, and the prevalence and predictive factors for sleep-disordered breathing in patients on opioids for chronic pain. We provide recommendations on how to evaluate patients on opioids for risk of moderate/severe sleep-disordered breathing in clinical care, which could lead to earlier use of therapeutic interventions for opioid-associated sleep-disordered breathing, such as opioid cessation or positive airway pressure therapy. This would improve quality of life and well-being of patients with chronic pain.

The Risk of Prior Opioid Exposure on Future Opioid Use and Comorbidities in Individuals With Non-Acute Musculoskeletal Knee Pain

Objectives

Due to their potentially deleterious effects, minimizing the use of opioids for musculoskeletal pain is a priority for healthcare systems. The objective of this study was to examine the risk of future opioid prescription use based on prior opioid use within a non-surgical cohort with musculoskeletal knee pain. We also examined the risk of pre-existing comorbidities on future opioid use, and the risk of prior opioid use on future comorbidities (sleep, mental health, cardiometabolic disorders).

Methods

Data came from the Military Health System Data Repository for 80 290 consecutive beneficiaries with an initial episode of care for patellofemoral pain from January 1, 2010 through December 31, 2011. Risk was calculated using 2 × 2 tables based on pre- and post-opioid utilization and comorbid diagnosis. Risk ratios, relative and absolute risk increases, and numbers needed to harm were calculated, all with 95% confidence intervals.

Results

Prior opioid use resulted in a risk ratio of 18.0 (95 CI 17.1, 19.0) and an absolute risk increase of 61.6% for future opioid use (numbers needed to harm = 2). The presence of all comorbidities (except cardiometabolic syndrome) were associated with a significant relative risk for future opioid use (RR range 1.2-1.5), but the absolute risk increase was trivial (range 0.7%-2.2%). The relative risk for a chronic pain diagnosis, traumatic brain injury/concussion, insomnia, depression, and PTSD were all significantly higher in those with prior opioid use (1.3-1.6), but absolute risk increase was minimal (1.1%-6.5%).

Discussion

Prior opioid use was a strong risk factor for future opioid use in non-surgical patients with knee pain. These findings show that history of prior opioid use is important when assessing the risk of future opioid use, whereas prior comorbidities may not be as important. Opioid history assessment should be standard practice for all patients with patellofemoral pain in whom an opioid prescription is considered.

Adaptive Servo-Ventilation: A Comprehensive Descriptive Study in the Geneva Lake Area

Background: Use of adaptive servo-ventilation (ASV) has been questioned in patients with central sleep apnea (CSA) and chronic heart failure (CHF). This study aims to detail the present use of ASV in clinical practice.

Methods: Descriptive, cross-sectional, multicentric study of patients undergoing long term (≥3 months) ASV in the Cantons of Geneva or Vaud (1,288,378 inhabitants) followed by public or private hospitals, private practitioners and/or home care providers.

Results: Patients included (458) were mostly male (392; 85.6%), overweight [BMI (median, IQR): 29 kg/m² (26; 33)], comorbid, with a median age of 71 years (59–77); 84% had been treated by CPAP before starting ASV. Indications for ASV were: emergent sleep apnea (ESA; 337; 73.6%), central sleep apnea (CSA; 108; 23.6%), obstructive sleep apnea (7; 1.5%), and overlap syndrome (6; 1.3%). Origin of CSA was cardiac (n = 30), neurological (n = 26), idiopathic (n = 28), or drug-related (n = 22). Among CSA cases, 60 (56%) patients had an echocardiography within the preceding 12 months; median left ventricular ejection fraction (LVEF) was 62.5% (54–65); 11 (18%) had a LVEF ≤45%. Average daily use of ASV was [mean (SD)] 368 (140) min; 13% used their device <3:30 h. Based on ventilator software, apnea-hypopnea index was normalized in 94% of subjects with data available (94% of 428).

Conclusions: Use of ASV has evolved from its original indication (CSA in CHF) to a heterogeneous predominantly male, aged, comorbid, and overweight population with mainly ESA or CSA. CSA in CHF represented only 6.5% of this population. Compliance and correction of respiratory events were satisfactory.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT04054570.

Opioid-Related Sleep-Disordered Breathing: An Update for Clinicians

Opioids are an effective treatment for patients with intractable pain. Long-term administration of opioids for pain relief is being delivered by an increasing number of medical providers in the United States including primary care physicians and nonspecialists. One common complication of chronic opioid use is sleep-disordered breathing which can result in various morbidities as well as an increase in all-cause mortality. It is important for providers to understand the relationship between opioids and sleep-disordered breathing as well as methods to improve diagnosis and strategies for treatment. This review aims to update clinicians on the mechanism, diagnosis, and treatment of opioid-related sleep-disordered breathing in order to improve the quality of care for patients with chronic pain.

Implications of Drug Use Disorders on Spine Surgery

BACKGROUND

The opioid crisis has been declared a "public health emergency." Spine surgeons are treating more patients with substance use disorders (SUDs).

OBJECTIVE

To investigate the outcomes of patients with SUD who undergo spine surgery.

METHODS

A retrospective chart review was performed on patients with SUD who underwent nonelective spine surgery by orthopedic or neurosurgical staff from 2012 to 2017 at a level 1 trauma center and spine referral center. Three elective cases were excluded.

RESULTS

A total of 49 patients undergoing 72 surgeries were reviewed. The most common substances of abuse were opioids (44/49 patients; 90%). Of 31 patients using multisubstances (63%), 29 misused opioids. The most common indications for surgery were infection (26/49, 53%), trauma (13/49, 27%), and myelopathy (7/49, 14%). Fusions (35/49, 71%) and irrigation and debridement surgeries (12/49, 24%) predominated. Twenty-nine percent (14/49) of patients had complications, the most common being hardware failure (7/49, 14%). Twenty percent (10/49) of patients left against medical advice and 22% (11/49) did not follow up after hospital discharge. The average length of hospital stay was 22 days. Forty-five percent (22/49) of patients were known to be in a drug program preoperatively versus 39% (19/49) postoperatively. Sixty-five percent (32/49) were prescribed opioids in the immediate postoperative period and 47% (23/49) continued to abuse drugs postoperatively.

CONCLUSIONS

Patients with SUD are at increased risk of complications and inadequate follow-up. Additional studies are warranted to determine whether additional perioperative education, psychiatry consultations, or prescription of opioid addiction treatment regimens will improve drug use cessation and outcomes.

Central sleep apnea: misunderstood and mistreated!

Central sleep apnea is prevalent in patients with heart failure, healthy individuals at high altitudes, and chronic opiate users and in the initiation of "mixed" (that is, central plus obstructive apneas). This brief review focuses on (a) the causes of repetitive, cyclical central apneas as mediated primarily through enhanced sensitivities in the respiratory control system and (b) treatment of central sleep apnea through modification of key components of neurochemical control as opposed to the current universal use of positive airway pressure.

Daytime sleepiness, functionality, and stress levels in chronic neck pain and effects of physical medicine and rehabilitation therapies on these situations

OBJECTIVE:

To evaluate the relationship between symptom severity, daytime sleepiness, and perceived stress levels and the impact of physical medicine & rehabilitation (PMR) therapies on these situations in chronic neck pain (CNP) conditions.

METHODS:

The study included 54 patients with CNP and 20 healthy control individuals. Patients with CNP were divided into two groups: the PMR therapy group (n=34) and the CNP control group (n=20). The PMR therapy programs of the patients included TENS, hot packs, therapeutic ultrasound, and exercises. Visual analog scale (VAS) at activity and resting for neck pain, Neck Disability Index (NDI), Perceived Stress Scale (PSS), Epworth Sleepiness Scale, chin-manubrium distances (CMD), and tragus-wall distances (TWD) values were evaluated before and after the treatment programs.

RESULTS:

Significant differences were found between the CNP patients and healthy controls regarding PSS, TWD, and CMD values. Furthermore, significant differences were detected between the PMR group and the CNP control group in the final evaluation of the VAS_resting, VAS_activity, PSS, and NDI levels.

CONCLUSION:

Evaluation of CNP from a single point of view can leave clinically missing points. Patients with CNP should be assessed for daytime sleepiness, stress levels, and functionality, and PMR therapies can be effective in relieving pain and psychological stress in patients with CNP.

Sleep, chronic pain, and opioid risk for apnea

Pain is an unwelcome sleep partner. Pain tends to erode sleep quality and alter the sleep restorative process in vulnerable patients. It can contribute to next-day sleepiness and fatigue, affecting cognitive function. Chronic pain and the use of opioid medications can also complicate the management of sleep disorders such as insomnia (difficulty falling and/or staying asleep) and sleep-disordered breathing (sleep apnea). Sleep problems can be related to various types of pain, including sleep headache (hypnic headache, cluster headache, migraine) and morning headache (transient tension type secondary to sleep apnea or to sleep bruxism or tooth grinding) as well as periodic limb movements (leg and arm dysesthesia with pain). Pain and sleep management strategies should be personalized to reflect the patient's history and ongoing complaints. Understanding the pain-sleep interaction requires assessments of: i) sleep quality, ii) potential contributions to fatigue, mood, and/or wake time functioning; iii) potential concomitant sleep-disordered breathing (SDB); and more importantly; iv) opioid use, as central apnea may occur in at-risk patients. Treatments include sleep hygiene advice, cognitive behavioral therapy, physical therapy, breathing devices (continuous positive airway pressure - CPAP, or oral appliance) and medications (sleep facilitators, e.g., zolpidem; or antidepressants, e.g., trazodone, duloxetine, or neuroleptics, e.g., pregabalin). In the presence of opioid-exacerbated SDB, if the dose cannot be reduced and normal breathing restored, servo-ventilation is a promising avenue that nevertheless requires close medical supervision.

Effects of Chronic Opioid Use on Sleep and Wake

Chronic use of opioids negatively affects sleep on 2 levels: sleep architecture and breathing. Patients suffer from a variety of daytime sequelae. There may be a bidirectional relationship between poor sleep quality, sleep-disordered breathing, and daytime function. Opioids are a potential cause of incident depression. The best therapeutic option is withdrawal of opioids, which proves difficult. Positive airway pressure devices are considered first-line treatment for sleep-related breathing disorders. New generation positive pressure servo ventilators are increasingly popular as a treatment option for opioid-induced sleep-disordered breathing. Treatments to improve sleep quality, sleep-related breathing disorders, and quality of life in patients who use opioids chronically are discussed.

Opioids Cause Central and Complex Sleep Apnea in Humans and Reversal With Discontinuation: A Plea for Detoxification

ABSTRACT

Central sleep apnea (CSA) and continuous positive airway pressure (CPAP) emergent CSA are common in patients for whom opioids have been prescribed for chronic pain management. It is not known if opioids are the potential cause of CSA. We report the case of a patient who underwent multiple full nights of polysomnography testing while on opioids, off opioids, and with various positive airway pressure devices. While on opioids, the patient had severe CSA that persisted during both CPAP and bilevel titration but was eliminated with adaptive servoventilation therapy. Some time later, opioid use was discontinued by the patient. Repeat polysomnography showed resolution of the sleep-disordered breathing. Later-while the patient was still off opioids-she had gained weight and become symptomatic; polysomnography showed obstructive sleep apnea without CSA. This time, therapy with CPAP showed elimination of sleep apnea without emergent CSA. These data collectively indicate that opioids were the cause of CSA as well as emergent CSA.

Novel Therapies for the Treatment of Central Sleep Apnea

Neurophysiologically, central apnea is due to a temporary cessation of respiratory rhythmogenesis in medullary respiratory networks. Central apneas occur in several disorders and result in pathophysiological consequences, including arousals and desaturation. The 2 most common causes in adults are congestive heart failure and chronic use of opioids to treat pain. Under such circumstances, diagnosis and treatment of central sleep apnea may improve quality of life, morbidity, and mortality. This article discusses recent developments in the treatment of central sleep apnea in heart failure and opioids use.

Can drugs induce or aggravate sleep apneas? A case-noncase study in VigiBase® , the WHO pharmacovigilance database

The potential favorizing role of drugs in sleep apnea syndrome (SAS) is unknown. This study investigates drugs associated with SAS in a pharmacovigilance database. SAS recorded as adverse drug reactions (ADRs) in VigiBase^® , the WHO pharmacovigilance database (more than 11 million reports), from 1978 to 2015 was selected. The risk of SAS reports was estimated using the case-noncase method, with cases being SAS and noncases all other recorded ADRs. During this 37-year period, 3325 ADRs including the word SAS were registered (0.05% of the database). Mean age was 51.2 ± 16.9 years with 52% men. ADRs were 'serious' in around 82% of cases. The case-noncase study found an association between SAS and exposition with sodium oxybate, rofecoxib, quetiapine, and clozapine for individual drugs and coxibs, antipsychotics, benzodiazepines, and opium alkaloids for drug classes. The potential role of other drugs is discussed. This study suggests that SAS can be associated with some drugs (mainly psychotropics) that are able to reveal or aggravate such a disease. Physicians should take into account the role of drugs in the etiological appraisal and management of SAS.

[Long-term opioid therapy in chronic noncancer pain. A systematic review and meta-analysis of efficacy, tolerability and safety in open-label extension trials with study duration of at least 26 weeks]

BACKGROUND

The efficacy and safety of long-term (≥ 6 months) opioid therapy (LtOT) in chronic noncancer pain (CNCP) is under debate. A systematic review with meta-analysis of the efficacy and harms of opioids in open-label extension studies of randomized controlled trials (RCTs) has not been conducted until now.

METHODS

We screened MEDLINE and clinicaltrials.gov (through to December 2013), as well as reference sections of systematic reviews of long-term RCTs of opioids in CNCP. We included open-label extension trials with a study duration ≥ 26 weeks of RCTs of ≥ 2 weeks duration. Using a random effects model, pooled estimates of event rates for categorical data and standardized mean differences (SMD) for continuous variables were calculated.

RESULTS

We included 11 open-label extension studies with 2445 participants with nociceptive (low back, osteoarthritis) and neuropathic (radicular, polyneuropathy) pain. Median study duration was 26 (range 26-108) weeks. Four studies tested oxycodone, two studies tramadol and buprenorphine; hydromorphone, morphine, oxymorphone and tapentadol were each tested in one study. Of the patients randomized at baseline, 28.5 % (95 % confidence interval, CI, 17.9-39.2 %) finished the open-label period; 53.5 % (95 % CI 38.1-68.2 %) of patients entering the open-label period finished the open-label period. In sum, the total loss was 71.5 % (95 % CI 60.9-83.1 %) of all patients primarily included into the RCT. A total of 4.9 % (95 % CI 2.9-8.2 %) of patients dropped out due lack of efficacy; 16.8 % (95 % CI 11.0-24.8 %) dropped out to due adverse events (AE) in the open-label period and 0.08 % (95 % CI 0.001-0.05 %) of patients died during the open-label period. Only one study systematically assessed aberrant drug behavior of the patients: 5.7 % (95 % CI 3.4-9.6 %) showed aberrant drug behavior in the opinion of the investigators and 2.6 % (95 % CI 1.2-5.8 %) were judged to show aberrant drug behavior by independent expert assessment. There was no significant change (p = 0.50) in pain intensity between the end of the randomized period and the end of open-label phase (SMD 0.19 [- 0.03, 0.41]; six studies with 1360 participants).

CONCLUSION

Only a minority of patients selected for opioid therapy at randomization finished the long-term open-label study. However, sustained effects of pain reduction could be demonstrated in these patients. LtOT can be considered in carefully selected and monitored CNCP patients who experience clinically meaningful pain reduction with at least tolerable AE in short-term opioid therapy. The English full-text version of this article is freely available at SpringerLink (under "Supplementary Material").

Definition, discrimination, diagnosis and treatment of central breathing disturbances during sleep

The complexity of central breathing disturbances during sleep has become increasingly obvious. They present as central sleep apnoeas (CSAs) and hypopnoeas, periodic breathing with apnoeas, or irregular breathing in patients with cardiovascular, other internal or neurological disorders, and can emerge under positive airway pressure treatment or opioid use, or at high altitude. As yet, there is insufficient knowledge on the clinical features, pathophysiological background and consecutive algorithms for stepped-care treatment. Most recently, it has been discussed intensively if CSA in heart failure is a “marker” of disease severity or a “mediator” of disease progression, and if and which type of positive airway pressure therapy is indicated. In addition, disturbances of respiratory drive or the translation of central impulses may result in hypoventilation, associated with cerebral or neuromuscular diseases, or severe diseases of lung or thorax. These statements report the results of an European Respiratory Society Task Force addressing actual diagnostic and therapeutic standards. The statements are based on a systematic review of the literature and a systematic two-step decision process. Although the Task Force does not make recommendations, it describes its current practice of treatment of CSA in heart failure and hypoventilation.

Recognition and response to opioid overdose deaths-New Mexico, 2012

PURPOSE

Drug overdose deaths are epidemic in the U.S. Prescription opioid pain relievers (OPR) and heroin account for the majority of drug overdoses. Preventing death after an opioid overdose by naloxone administration requires the rapid identification of the overdose by witnesses. This study used a state medical examiner database to characterize fatal overdoses, evaluate witness-reported signs of overdose, and identify opportunities for intervention.

METHODS

We reviewed all unintentional drug overdose deaths that occurred in New Mexico during 2012. Data were abstracted from medical examiner records at the New Mexico Office of the Medical Investigator. We compared mutually exclusive groups of OPR and heroin-related deaths.

RESULTS

Of the 489 overdose deaths reviewed, 49.3% involved OPR, 21.7% involved heroin, 4.7% involved a mixture of OPR and heroin, and 24.3% involved only non-opioid substances. The majority of OPR-related deaths occurred in non-Hispanic whites (57.3%), men (58.5%), persons aged 40-59 years (55.2%), and those with chronic medical conditions (89.2%). Most overdose deaths occurred in the home (68.7%) and in the presence of bystanders (67.7%). OPR and heroin deaths did not differ with respect to paramedic dispatch and CPR delivery, however, heroin overdoses received naloxone twice as often (20.8% heroin vs. 10.0% OPR; p<0.01).

CONCLUSION

OPR overdose deaths differed by age, health status, and the presence of bystanders, yet received naloxone less often when compared to heroin overdose deaths. These findings suggest that naloxone education and distribution should be targeted in future prevention efforts.

Ventilation and the Response to Hypercapnia after Morphine in Opioid-naive and Opioid-tolerant Rats

BACKGROUND

Opioid-related deaths are a leading cause of accidental death, with most occurring in patients receiving chronic pain therapy. Respiratory arrest is the usual cause of death, but mechanisms increasing that risk with increased length of treatment remain unclear. Repeated administration produces tolerance to opioid analgesia, prompting increased dosing, but depression of ventilation may not gain tolerance to the same degree. This study addresses differences in the degree to which chronic morphine (1) produces tolerance to ventilatory depression versus analgesia and (2) alters the magnitude and time course of ventilatory depression.

METHODS

Juvenile rats received subcutaneous morphine for 3 days (n = 116) or vehicle control (n = 119) and were then tested on day 4 following one of a range of morphine doses for (a) analgesia by paw withdraw from heat or (b) respiratory parameters by plethysmography-respirometry.

RESULTS

Rats receiving chronic morphine showed significant tolerance to morphine sedation and analgesia (five times increased ED50). When sedation was achieved for all animals in a dose group (lowest effective doses: opioid-tolerant, 15 mg/kg; opioid-naive, 3 mg/kg), the opioid-tolerant showed similar magnitudes of depressed ventilation (-41.4 ± 7.0%, mean ± SD) and hypercapnic response (-80.9 ± 15.7%) as found for morphine-naive (-35.5 ± 16.9% and -67.7 ± 15.1%, respectively). Ventilation recovered due to tidal volume without recovery of respiratory rate or hypercapnic sensitivity and more slowly in morphine-tolerant.

CONCLUSIONS

In rats, gaining tolerance to morphine analgesia does not reduce ventilatory depression effects when sedated and may inhibit recovery of ventilation.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

Medium Increased Risk for Central Sleep Apnea but Not Obstructive Sleep Apnea in Long-Term Opioid Users: A Systematic Review and Meta-Analysis

STUDY OBJECTIVE

Opioids are associated with higher risk for ataxic breathing and sleep apnea. We conducted a systematic literature review and meta-analysis to assess the influence of long-term opioid use on the apnea-hypopnea and central apnea indices (AHI and CAI, respectively).

METHODS

A systematic review protocol (Cochrane Handbook guidelines) was developed for the search and analysis. We searched Embase, Medline, ACP Journal Club, and Cochrane Database up to November 2014 for three topics: (1) narcotics, (2) sleep apnea, and (3) apnea-hypopnea index. The outcome of interest was the variation in AHI and CAI in opioid users versus non-users. Two reviewers performed the data search and extraction, and disagreements were resolved by discussion. Results were combined by standardized mean difference using a random effect model, and heterogeneity was tested by χ(2) and presented as I(2) statistics.

RESULTS

Seven studies met the inclusion criteria, for a total of 803 patients with obstructive sleep apnea (OSA). We compared 2 outcomes: AHI (320 opioid users and 483 non-users) and 790 patients with CAI (315 opioid users and 475 non-users). The absolute effect size for opioid use was a small increased in apnea measured by AHI = 0.25 (95% CI: 0.02-0.49) and a medium for CAI = 0.45 (95% CI: 0.27-0.63). Effect consistency across studies was calculated, showing moderate heterogeneity at I(2) = 59% and 29% for AHI and CAI, respectively.

CONCLUSIONS

The meta-analysis results suggest that long-term opioid use in OSA patients has a medium effect on central sleep apnea.

A novel adaptive servoventilation (ASVAuto) for the treatment of central sleep apnea associated with chronic use of opioids

STUDY OBJECTIVES

To compare the efficacy and patient comfort of a new mode of minute ventilation-targeted adaptive servoventilation (ASVAuto) with auto-titrating expiratory positive airway pressure (EPAP) versus bilevel with back-up respiratory rate (bilevel-ST) in patients with central sleep apnea (CSA) associated with chronic use of opioid medications.

METHODS

Prospective, randomized, crossover polysomnography (PSG) study. Eighteen consecutive patients (age ≥ 18 years) who had been receiving opioid therapy (≥ 6 months), and had sleep disordered breathing with CSA (central apnea index [CAI] ≥ 5) diagnosed during an overnight sleep study or positive airway pressure (PAP) titration were enrolled to undergo 2 PSG studies-one with ASVAuto and one with bilevel-ST. Patients completed 2 questionnaires after each PSG; Morning After Patient Satisfaction Questionnaire and PAP Comfort Questionnaire.

RESULTS

Patients had a mean age of 52.9 ± 15.3 years. PSG prior to randomization showed an apnea hypopnea index (AHI) of 50.3 ± 22.2 and CAI of 13.0 ± 18.7. Titration with ASVAuto versus bilevel-ST showed that there were significant differences with respect to AHI and CAI. The AHI and CAI were significantly lower on ASVAuto than bilevel-ST (2.5 ± 3.5 versus 16.3 ± 20.9 [p = 0.0005], and 0.4 ± 0.8 versus 9.4 ± 18.8 [p = 0.0002], respectively). Respiratory parameters were normalized in 83.3% of patients on ASVAuto versus 33.3% on bilevel-ST. Patients felt more awake and alert on ASVAuto than bilevel-ST based on scores from Morning After Patient Satisfaction Questionnaire (p = 0.0337).

CONCLUSIONS

The ASVAuto was significantly more effective than bilevel-ST for the treatment of CSA associated with chronic opioid use.

Adaptive servoventilation for treatment of opioid-associated central sleep apnea

RATIONALE

Opioids have become part of contemporary treatment in the management of chronic pain. Although severe daytime ventilatory depression is uncommon, chronic use of opioids could be associated with severe central and obstructive sleep apnea.

OBJECTIVES

To determine the acute efficacy, and prolonged use of adaptive servoventilation (ASV) to treat central sleep apnea in patients on chronic opioids.

METHODS

Twenty patients on opioid therapy referred for evaluation of obstructive sleep apnea (OSA) were found to have central sleep apnea (CSA). The first 16 patients underwent continuous positive airway pressure (CPAP) titration, which showed persistent CSA. With the notion that CSA will be eliminated with continued use of CPAP, 4 weeks later, 9 of the 16 patients underwent a second CPAP titration which proved equally ineffective. Therefore, therapy with CPAP was abandoned. All patients underwent ASV titration.

MAIN RESULTS

Diagnostic polysomnography showed an average apnea-hypopnea index (AHI) of 61/h and a central-apnea index (CAI) of 32/h. On CPAP 1, AHI was 34/h and CAI was 20/h. Respective indices on CPAP 2 were AHI 33/h and CAI 19/h. During titration with ASV, CAI was 0/h and the average HI was 11/h on final pressures. With a reduction in AHI, oxyhemoglobin saturation nadir increased from 83% to 90%, and arousal index decreased from 29/h of sleep to 12/h on final ASV pressures. Seventeen patients were followed for a minimum of 9 months and up to 6 years. The mean long-term adherence was 5.1 ± 2.5 hours.

CONCLUSIONS

Chronic use of opioids could be associated with severe CSA which remains resistant to CPAP therapy. ASV device is effective in the treatment of CSA and over the long run, most patients remain compliant with the device. Randomized long-term studies are necessary to determine if treatment of sleep apnea with ASV improves quality of life and the known mortality associated with opioids.

Obstructive sleep apnea and other sleep-related syndromes

Obstructive sleep apnea syndrome (OSAS) is a common disorder characterized by repetitive episodes of breathing cessation due to complete or partial collapse of the upper airway therefore affecting ventilation. It is quite common, with a prevalence of about 2-4%, has a strong genetic component, and creates a proinflammatory state with elevated TNFα and other cytokines. If untreated, OSA can lead to significant neurological problems that include stroke, cognitive decline, depression, headaches, peripheral neuropathy, and nonarteritic ischemic optic neuropathy (NAION). Treatment reverses some of these neurological problems. Treatment includes continuous positive airway pressure and its variants, oral appliances, weight loss, upper airway surgery, and rarely maxillofacial procedures. Other sleep breathing disorders such as hypoventilation, central sleep apnea, complex sleep apnea, and Cheyne-Stokes respiration are less common and are sometimes associated with neuromuscular disorders causing diaphragmatic paralysis, but can also be seen in opiate exposure and severe obesity.

Central sleep apnea

Neurophysiologically, central apnea is due to a temporary failure in the pontomedullary pacemaker generating breathing rhythm. As a polysomnographic finding, central apneas occur in many pathophysiological conditions. Depending on the cause or mechanism, central apneas may not be clinically significant, for example, those that occur normally at sleep onset. In contrast, central apneas occur in a number of disorders and result in pathophysiological consequences. Central apneas occur commonly in high-altitude sojourn, disrupt sleep, and cause desaturation. Central sleep apnea also occurs in number of disorders across all age groups and both genders. Common causes of central sleep apnea in adults are congestive heart failure and chronic use of opioids to treat pain. Under such circumstances, diagnosis and treatment of central sleep apnea may improve quality of life, morbidity, and perhaps mortality. The mechanisms of central sleep apnea have been best studied in congestive heart failure and hypoxic conditions when there is increased CO2 sensitivity below eupnea resulting in lowering eupneic PCO2 below apneic threshold causing cessation of breathing until the PCO2 rises above the apneic threshold when breathing resumes. In many other disorders, the mechanism of central sleep apnea (CSA) remains to be investigated.

Positive airway pressure therapy in patients with opioid-related central sleep apnea

PURPOSE

This study aims to compare treatment response and adherence rate to positive airway pressure (PAP) in patients with opioid-related central sleep apnea (O-CSA) and idiopathic central sleep apnea (I-CSA).

METHODS

We performed a retrospective chart over a 5-year period performed at a VA sleep center. Continuous PAP (CPAP) was prescribed initially for all participants. For those nonresponders (apnea hypopnea index (AHI) of >10/h), bi-level PAP (BiPAP) or adaptive servoventilation (ASV) was instituted upon provider's discretion. Adherence to therapy was checked with the built-in meter.

RESULTS

Thirty-four patients with O-CSA and 61 with I-CSA were included in the analysis. The two groups were comparable with respect to age, body mass index (BMI), Epworth Sleepiness Scale, and burden of comorbidities. The mean daily equivalent dose of morphine in the O-CSA was 168 mg (range 30-1,217 mg). In the O-CSA group, 24% of PAP-naïve patients responded to CPAP compared to 38% in the I-CSA group. BiPAP and ASV were comparable in eliminating central events in both O-CSA (66 versus 60 %) and I-CSA (93 versus 90%), respectively. Eight patients (24%) with O-CSA and six patients (10%) with I-CSA were considered nonresponders. The adherence rate was 48 and 24% in the I-CSA group compared to 23 and 18% in the O-CSA group at 3 and 12 months following initiation of effective treatment (p = 0.04 and p = 0.6).

CONCLUSIONS

The presence of O-CSA does not preclude an adequate response to CPAP. Adherence rate to PAP was poor in both the O-CSA and I-CSA groups. Further studies are needed to define optimal adherence rate and long-term benefits of PAP in CSA.

Sleep-disordered breathing

PURPOSE OF REVIEW

This article introduces readers to the clinical presentation, diagnosis, and treatment of sleep-disordered breathing and reviews the associated risk factors and health consequences.

RECENT FINDINGS

Sleep-disordered breathing is associated with significant impairments in daytime alertness and cognitive function as well as adverse health outcomes. The initial treatment of choice is positive airway pressure. Improvements in technology and mask delivery systems have helped to make this treatment more comfortable and convenient for many patients.

SUMMARY

Sleep-disordered breathing, particularly in the form of obstructive sleep apnea, is highly prevalent in the general population and has important implications for neurology patients. Sleep-disordered breathing is characterized by repetitive periods of cessation in breathing, termed apneas, or reductions in the amplitude of a breath, known as hypopneas, that occur during sleep. These events are frequently associated with fragmentation of sleep, declines in oxygen saturation, and sympathetic nervous system activation with heart rate and blood pressure elevation. Obstructive sleep apnea, which represents cessation of airflow, develops because of factors such as anatomic obstruction of the upper airway related to obesity, excess tissue bulk in the pharynx, and changes in muscle tone and nerve activity during sleep. Central sleep apnea represents cessation of airflow along with absence or significant reduction in respiratory effort during sleep and is more commonly found in the setting of congestive heart failure, neurologic disorders, or cardiopulmonary disease.

The effect of opioid therapy on endocrine function

Opioids are an established option in the analgesic armamentarium for managing moderate-to-severe chronic pain. Long-term opioid use, however, is associated with several potential adverse effects and toxicities, such as peripheral edema, immune suppression, hyperalgesia, sleep apnea, and changes in endocrine function, many of which are not fully appreciated. Opioid endocrinopathy can greatly affect patients, causing reduced sexual function, decreased libido, infertility, mood disorders, osteoporosis, and osteopenia. Furthermore, although opioid endocrinopathy appears to be common, many patients do not report their symptoms, thus causing this adverse effect to go unnoticed and without clinical monitoring, particularly in patients chronically taking the equivalent of ≥ 100 mg of morphine daily. Indeed, diagnosing hypogonadism as opioid-related can be challenged by other influences on endocrine function, such as pain pathophysiology, comorbidities, other drug therapies, and patient age. Management options for opioid endocrinopathy include discontinuing opioid therapy, reducing the opioid dose, switching to a different opioid, and hormone supplementation.