The effect of acute morphine on obstructive sleep apnoea: a randomised double-blind placebo-controlled crossover trial

Australasian Sleep Association position statement on consensus and evidence based treatment for primary snoring

Primary snoring impacts a significant portion of the adult population and has the potential to significantly impair quality of life. The purpose of these guidelines is to provide evidence-based recommendations to assist Australasian practitioners in the management of adult patients who present with primary snoring without significant obstructive sleep apnoea. The Timetable, Methodology and Standards by which this Position Statement has been established is outlined in the Appendix S1. The main recommendations are: Weight loss, and reduced alcohol consumption should be recommended, where appropriate If clinical judgement dictates, benzodiazepine and opioid reduction or avoidance may be advised Positional therapy should be considered in supine dominant snorers In dentate patients, Mandibular advancement devices (MAD) should be recommended as a first line treatment following assessment by both an appropriate Dentist and Sleep physician Continuous positive airway pressure (CPAP) devices may be recommended in patients with primary snoring in those already committed to their use or willing to try Surgical treatment of primary snoring by an appropriately credentialled surgeon may be advised and includes nasal (adjunctive), palatal and other interventions This position statement has been designed based on the best available current evidence and our combined expert clinical experience to facilitate the management of patients who present with primary snoring. It provides clinicians with a series of both non-surgical and surgical options with the aim of achieving optimal symptom control and patient outcomes. This is the first such set of recommendations to be established within Australasia and has also been reviewed and endorsed by the Australasian Sleep Association.

Association Between Race and Opioid-Induced Respiratory Depression: An International Post Hoc Analysis of the Prediction of Opioid-induced Respiratory Depression In Patients Monitored by Capnography Trial

BACKGROUND

Opioid-induced respiratory depression (OIRD) is common on the medical and surgical wards and is associated with increased morbidity and health care costs. While previous studies have investigated risk factors for OIRD, the role of race remains unclear. We aim to investigate the association between race and OIRD occurrence on the medical/surgical ward.

METHODS

This is a post hoc analysis of the PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial; a prospective multinational observational blinded study of 1335 general ward patients who received parenteral opioids and underwent blinded capnography and oximetry monitoring to identify OIRD episodes. For this study, demographic and perioperative data, including race and comorbidities, were analyzed and assessed for potential associations with OIRD. Univariable χ 2 and Mann-Whitney U tests were used. Stepwise selection of all baseline and demographic characteristics was used in the multivariable logistic regression analysis.

RESULTS

A total of 1253 patients had sufficient racial data (317 Asian, 158 Black, 736 White, and 42 other races) for inclusion. The incidence of OIRD was 60% in Asians (N = 190/317), 25% in Blacks (N = 40/158), 43% in Whites (N = 316/736), and 45% (N = 19/42) in other races. Baseline characteristics varied significantly: Asians were older, more opioid naïve, and had higher opioid requirements, while Blacks had higher incidences of heart failure, obesity, and smoking. Stepwise multivariable logistic regression revealed that Asians had increased risk of OIRD compared to Blacks (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.54-4.04; P = .0002) and Whites (OR, 1.38; 95% CI, 1.01-1.87; P = .0432). Whites had a higher risk of OIRD compared to Blacks (OR, 1.81; 95% CI, 1.18-2.78; P = .0067). The model's area under the curve was 0.760 (95% CI, 0.733-0.787), with a Hosmer-Lemeshow goodness-of-fit test P value of .23.

CONCLUSIONS

This post hoc analysis of PRODIGY found a novel association between Asian race and increased OIRD incidence. Further study is required to elucidate its underlying mechanisms and develop targeted care pathways to reduce OIRD in susceptible populations.

Opioid Use Disorder, Sleep Deficiency, and Ventilatory Control: Bidirectional Mechanisms and Therapeutic Targets

Opioid use continues to rise globally. So too do the associated adverse consequences. Opioid use disorder (OUD) is a chronic and relapsing brain disease characterized by loss of control over opioid use and impairments in cognitive function, mood, pain perception, and autonomic activity. Sleep deficiency, a term that encompasses insufficient or disrupted sleep due to multiple potential causes, including sleep disorders, circadian disruption, and poor sleep quality or structure due to other medical conditions and pain, is present in 75% of patients with OUD. Sleep deficiency accompanies OUD across the spectrum of this addiction. The focus of this concise clinical review is to highlight the bidirectional mechanisms between OUD and sleep deficiency and the potential to target sleep deficiency with therapeutic interventions to promote long-term, healthy recovery among patients in OUD treatment. In addition, current knowledge on the effects of opioids on sleep quality, sleep architecture, sleep-disordered breathing, sleep apnea endotypes, ventilatory control, and implications for therapy and clinical practice are highlighted. Finally, an actionable research agenda is provided to evaluate the basic mechanisms of the relationship between sleep deficiency and OUD and the potential for behavioral, pharmacologic, and positive airway pressure treatments targeting sleep deficiency to improve OUD treatment outcomes.

Clinical implications of opioid-induced ventilatory impairment

Opioid-induced ventilatory impairment is the primary mechanism of harm from opioid use. Opioids suppress the activity of the central respiratory centres and are sedating, leading to impairment of alveolar ventilation.Respiratory physiological changes induced with acute opioid use include depression of the hypercapnic ventilatory response and hypoxic ventilatory response. In chronic opioid use a compensatory increase in hypoxic ventilatory response maintains ventilation and contributes to the onset of sleep-disordered breathing patterns of central sleep apnoea and ataxic breathing. Supplemental oxygen use in those at risk of opioid-induced ventilatory impairment requires careful consideration by the clinician to prevent failure to detect hypoventilation, if oximetry is being relied on, and the overriding of hypoxic ventilatory drive. Obstructive sleep apnoea and opioid-induced ventilatory impairment are frequently associated, with this interrelationship being complex and often unpredictable. Monitoring the patient for opioid-induced ventilatory impairment poses challenges in the areas of reliability, avoidance of alarm fatigue, cost, and personnel demands. Many situations remain in which patients cannot be provided effective analgesia without opioids, and for these the clinician requires a comprehensive knowledge of opioid-induced ventilatory impairment.

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.

The Relationship Between Postoperative Opioid Analgesia and Sleep Apnea Severity in Patients Undergoing Hip Arthroplasty: A Randomized, Controlled, Triple-Blinded Trial

PURPOSE

Residual postoperative pain after hip arthroplasty is usually treated with oral opioids. While classic opioids are associated with respiratory depression and worsening of sleep apnea, tramadol has been reported to preserve respiratory function. However, this has not been investigated in a prospective trial using respiratory polygraphy. This randomized controlled triple-blinded trial tested the hypothesis that postoperative treatment with oral opioids such as oxycodone would increase sleep apnea severity, measured with a respiratory polygraphy, compared with oral tramadol.

PATIENTS AND METHODS

Sixty patients undergoing hip arthroplasty under spinal anesthesia with 15 mg isobaric bupivacaine 0.5% were randomized to receive postoperative pain treatment with either oral oxycodone (controlled-release 10 mg every 12 hours and immediate-release 5 mg every 4 hours as needed) or oral tramadol (controlled-release 100 mg every 8 hours and immediate-release 50 mg every 4 hours as needed). Respiratory polygraphy was performed on the first postoperative night. The primary outcome was the apnea-hypopnea index in the supine position. Secondary outcomes included the oxygen desaturation index, postoperative pain scores and intravenous morphine consumption.

RESULTS

Mean supine apnea-hypopnea index on postoperative night 1 was 11.3 events.h^-1 (95% confidence interval, 4.8-17.7) in the oxycodone group and 10.7 (4.6-16.8) events.h^-1 in the tramadol group (p=0.89). There were no significant differences between the oxycodone and tramadol groups with respect to any secondary sleep-related or pain-related outcomes.

CONCLUSION

Oral oxycodone did not increase sleep apnea severity measured using respiratory polygraphy compared with oral tramadol on the first postoperative night after hip arthroplasty.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov - NCT03454217 (date of registration: 05/03/2018).

The influence of acute morphine use on obstructive sleep apnea: A systematic review and meta-analysis

The present study was conducted to systematically evaluate the acute effect of morphine on obstructive sleep apnea (OSA). The PubMed, Embase, Cochrane Library, Clinicaltrials.gov, China National Knowledge Infrastructure (CNKI), and Wan-Fang databases were searched for randomised controlled trials studying the influence of morphine on OSA published up to May 24, 2021. The Cochrane risk of bias tool was used to assess study quality and meta-analysis was performed on the included clinical trial results to quantify the impact of morphine on various sleep and respiratory parameters. Three studies (n = 132 patients) were ultimately examined. There were no significant differences between patients with OSA taking morphine and placebo/non-opioids with respect to the sleep Apnea-Hypopnea Index (mean difference [MD] 1.78, 95% confidence interval [CI] -2.41, 5.98; p > 0.05); Oxygen Desaturation Index (MD 1.49, 95% CI -3.21, 6.19; p > 0.05); Obstructive Sleep Apnea Index (MD 0.83, 95% CI -2.08, 3.75; p > 0.05); Hypopnea Index (MD -0.01, 95% CI -2.64, 2.63; p > 0.05); lowest oxygen saturation (MD 0.68, 95% CI -4.50, 5.86; p > 0.05); or sleep oxygen saturation >90% (MD 0.10, 95% CI -1.14, 1.34; p > 0.05). In conclusion, a single dose of 30 or 40 mg morphine does not have a significant effect on sleep or respiratory outcomes compared to placebo in patients with OSA, challenging the orthodoxy that opioids worsen OSA.

Obesity and Obesity Hypoventilation, Sleep Hypoventilation, and Postoperative Respiratory Failure

Obesity hypoventilation syndrome (OHS) is considered as a diagnosis in obese patients (body mass index [BMI] ≥30 kg/m2) who also have sleep-disordered breathing and awake diurnal hypercapnia in the absence of other causes of hypoventilation. Patients with OHS have a higher burden of medical comorbidities as compared to those with obstructive sleep apnea (OSA). This places patients with OHS at higher risk for adverse postoperative events. Obese patients and those with OSA undergoing elective noncardiac surgery are not routinely screened for OHS. Screening for OHS would require additional preoperative evaluation of morbidly obese patients with severe OSA and suspicion of hypoventilation or resting hypoxemia. Cautious selection of the type of anesthesia, use of apneic oxygenation with high-flow nasal cannula during laryngoscopy, better monitoring in the postanesthesia care unit (PACU) can help minimize adverse perioperative events. Among other risk-reduction strategies are proper patient positioning, especially during intubation and extubation, multimodal analgesia, and cautious use of postoperative supplemental oxygen.

Pharmacologically Induced Ventilatory Depression in the Postoperative Patient: A Sleep-Wake State-Dependent Perspective

Pharmacologically induced ventilatory depression (PIVD) is a common postoperative complication with a spectrum of severity ranging from mild hypoventilation to severe ventilatory depression, potentially leading to anoxic brain injury and death. Recent studies, using continuous monitoring technologies, have revealed alarming rates of previously undetected severe episodes of postoperative ventilatory depression, rendering the recognition of such episodes by the standard intermittent assessment practice, quite problematic. This imprecise description of the epidemiologic landscape of PIVD has thus stymied efforts to understand better its pathophysiology and quantify relevant risk factors for this postoperative complication. The residual effects of various perianesthetic agents on ventilatory control, as well as the multiple interactions of these drugs with patient-related factors and phenotypes, make postoperative recovery of ventilation after surgery and anesthesia a highly complex physiological event. The sleep-wake, state-dependent variation in the control of ventilation seems to play a central role in the mechanisms potentially enhancing the risk for PIVD. Herein, we discuss emerging evidence regarding the epidemiology, risk factors, and potential mechanisms of PIVD.

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.

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.

The effect of acute morphine on sleep in male patients suffering from sleep apnea: Is there a genetic effect? An RCT Study

Questionnaire-based studies have suggested genetic differences in sleep symptoms in chronic opioid users. The present study aims to investigate if there is a genetic effect on sleep architecture and quantitative electroencephalogram (EEG) in response to acute morphine. Under a randomized, double-blind, placebo-controlled, crossover design, 68 men with obstructive sleep apnea undertook two overnight polysomnographic studies conducted at least 1 week apart. Each night they received either 40 mg of controlled-release morphine or placebo. Sleep architecture and quantitative EEG were compared between conditions. Blood was sampled before sleep and on the next morning for genotyping and pharmacokinetic analyses. We analysed three candidate genes (OPRM1 [rs1799971, 118 A > G], ABCB1[rs1045642, 3435 C > T] and HTR3B [rs7103572 C > T]). We found that morphine decreased slow wave sleep and rapid eye movement sleep and increased stage 2 sleep. Those effects were less in subjects with HTR3B CT/TT than in those with CC genotype. Similarly, sleep onset latency was shortened in the ABCB1 CC subgroup compared with the CT/TT subgroup. Total sleep time was significantly increased in ABCB1 CC but not in CT/TT subjects. Sleep apnea and plasma morphine and metabolite concentration were not confounding factors for these genetic differences in sleep. With morphine, patients had significantly more active/unstable EEG (lower delta/alpha ratio) during sleep. No genetic effects on quantitative EEG were detected. In summary, we identified two genes (HTR3B and ABCB1) with significant variation in the sleep architecture response to morphine. Morphine caused a more active/unstable EEG during sleep. Our findings may have relevance for a personalized medicine approach to targeted morphine therapy.

Postoperative Critical Events Associated With Obstructive Sleep Apnea: Results From the Society of Anesthesia and Sleep Medicine Obstructive Sleep Apnea Registry

BACKGROUND

Obstructive sleep apnea (OSA) patients are at increased risk for pulmonary and cardiovascular complications; perioperative mortality risk is unclear. This report analyzes cases submitted to the OSA Death and Near Miss Registry, focusing on factors associated with poor outcomes after an OSA-related event. We hypothesized that more severe outcomes would be associated with OSA severity, less intense monitoring, and higher cumulative opioid doses.

METHODS

Inclusion criteria were age ≥18 years, OSA diagnosed or suspected, event related to OSA, and event occurrence 1992 or later and <30 days postoperatively. Factors associated with death or brain damage versus other critical events were analyzed by tests of association and odds ratios (OR; 95% confidence intervals [CIs]).

RESULTS

Sixty-six cases met inclusion criteria with known OSA diagnosed in 55 (83%). Patients were middle aged (mean = 53, standard deviation [SD] = 15 years), American Society of Anesthesiologists (ASA) III (59%, n = 38), and obese (mean body mass index [BMI] = 38, SD = 9 kg/m); most had inpatient (80%, n = 51) and elective (90%, n = 56) procedures with general anesthesia (88%, n = 58). Most events occurred on the ward (56%, n = 37), and 14 (21%) occurred at home. Most events (76%, n = 50) occurred within 24 hours of anesthesia end. Ninety-seven percent (n = 64) received opioids within the 24 hours before the event, and two-thirds (41 of 62) also received sedatives. Positive airway pressure devices and/or supplemental oxygen were in use at the time of critical events in 7.5% and 52% of cases, respectively. Sixty-five percent (n = 43) of patients died or had brain damage; 35% (n = 23) experienced other critical events. Continuous central respiratory monitoring was in use for 3 of 43 (7%) of cases where death or brain damage resulted. Death or brain damage was (1) less common when the event was witnessed than unwitnessed (OR = 0.036; 95% CI, 0.007-0.181; P < .001); (2) less common with supplemental oxygen in place (OR = 0.227; 95% CI, 0.070-0.740; P = .011); (3) less common with respiratory monitoring versus no monitoring (OR = 0.109; 95% CI, 0.031-0.384; P < .001); and (4) more common in patients who received both opioids and sedatives than opioids alone (OR = 4.133; 95% CI, 1.348-12.672; P = .011). No evidence for an association was observed between outcomes and OSA severity or cumulative opioid dose.

CONCLUSIONS

Death and brain damage were more likely to occur with unwitnessed events, no supplemental oxygen, lack of respiratory monitoring, and coadministration of opioids and sedatives. It is important that efforts be directed at providing more effective monitoring for OSA patients following surgery, and clinicians consider the potentially dangerous effects of opioids and sedatives-especially when combined-when managing OSA patients postoperatively.

Concomitant benzodiazepine and opioids decrease sleep apnoea risk in chronic pain patients

Background

The concurrent use of sedating centrally acting drugs and opioids by chronic pain patients occurs routinely despite concerns of negative impacts on respiration during sleep. The effects of centrally acting drugs and opioids on sleep apnoea have not been well characterised. The objective of this study was to assess the effect of concomitant centrally acting drugs and opioids on the prevalence and severity of sleep apnoea in chronic pain patients.

Methods

We conducted a prospective cohort study at five chronic pain clinics. Each participant underwent an in-laboratory polysomnography and daily morphine milligram equivalents were calculated. Participants were grouped into centrally acting drugs and opioid users versus sole opioid users.

Results

Of the 332 consented participants, 204 underwent polysomnography and 120 (58.8%) had sleep apnoea (72% obstructive, 20% central, and 8% indeterminate sleep apnoea). Overall, 35% (71 of 204) were taking opioids alone, and 65% (133 of 204) were taking centrally acting drugs and opioids. There was a 69% decrease in the odds of having sleep apnoea (apnoea–hypopnoea index ≥5 events·h⁻¹) in participants taking benzodiazepine/opioids versus sole opioid users (OR 0.31, 95% CI:0.12–0.80, p=0.015). Additionally, concomitant benzodiazepine/opioids versus sole opioid use was associated with a decrease in respiratory arousal index scores (p=0.03). Mean overnight S_pO2 was approximately 1% lower in the concomitant benzodiazepine/opioids group versus sole opioid users (93.1±2.5 versus 94.4±2.1%, p=0.01).

Conclusion

In chronic pain patients on opioids, administration of certain benzodiazepine sedatives induced a mild respiratory depression but paradoxically reduced sleep apnoea risk and severity by increasing the respiratory arousal threshold.

There may be potential to reduce sleep apnoea risk and severity in specific chronic pain patients on opioids using certain benzodiazepine sedatives by selecting those with a low respiratory arousal threshold in whom sleep promotion may stabilise breathinghttps://bit.ly/2Zj4WX1

Improvement of Petroselinum crispum on Morphine Toxicity in Prefrontal Cortex in Rats

Background:

Petroselinum crispum (P. Crispum) is an associate of the umbelliferae family with several therapeutic attributes. Morphine is known as a major risk factor in the development of functional disorder of several organs.

Objective:

This study was designed to evaluate the effects of P. Crispum extract against morphine-induced damage to the brain prefrontal cortex (PC) of rats.

Materials and Methods:

In this experimental study, 64 Wistar male rats were randomly assigned to 8 groups: Sham group, Morphine group, P. Crispum groups (50, 100, and 150 mg/kg), and Morphine + P. Crispum groups. Daily intraperitoneal treatment applied for 20 days. Ferric reducing/antioxidant power method was hired to determine the total antioxidant capacity (TAC). The number of dendritic spines was investigated by Golgi staining technique. Cresyl violet staining method was used to determine the number of neurons in the PC region. Furthermore, Griess technique was used to determine the level of serum nitrite oxide.

Results:

Morphine administration increased nitrite oxide levels and decreased TAC, density of neuronal dendritic spines and neurons compared to the sham group significantly (P < 0.05). In whole doses of the P. Crispum and Morphine + P. Crispum groups, the number of neurons and neuronal dendritic spines increased significantly while nitrite oxide level and TAC decreased compared to the morphine group (P < 0.05).

Conclusion:

It seems that the administration of P. Crispum extract protects the animals against oxidative stress and nitrite oxide, also improves some PC parameters including the number of neurons, and dendritic spines because of the morphine application.

Morphine alters respiratory control but not other key obstructive sleep apnoea phenotypes: a randomised trial

Accidental opioid-related deaths are increasing. These often occur during sleep. Opioids such as morphine may worsen obstructive sleep apnoea (OSA). Thus, people with OSA may be at greater risk of harm from morphine. Possible mechanisms include respiratory depression and reductions in drive to the pharyngeal muscles to increase upper airway collapsibility. However, the effects of morphine on the four key phenotypic causes of OSA (upper airway collapsibility (pharyngeal critical closure pressure; Pcrit), pharyngeal muscle responsiveness, respiratory arousal threshold and ventilatory control (loop gain) during sleep) are unknown.

21 males with OSA (apnoea–hypopnoea index range 7–67 events·h−1) were studied on two nights (1-week washout) according to a double-blind, randomised, cross-over design (ACTRN12613000858796). Participants received 40 mg of MS-Contin on one visit and placebo on the other. Brief reductions in continuous positive airway pressure (CPAP) from the therapeutic level were delivered to induce airflow limitation during non-rapid eye movement (REM) sleep to quantify the four phenotypic traits. Carbon dioxide was delivered via nasal mask on therapeutic CPAP to quantify hypercapnic ventilatory responses during non-REM sleep.

Compared to placebo, 40 mg of morphine did not change Pcrit (−0.1±2.4 versus −0.4±2.2 cmH2O, p=0.58), genioglossus muscle responsiveness (−2.2 (−0.87 to −5.4) versus −1.2 (−0.3 to −3.5) μV·cmH2O−1, p=0.22) or arousal threshold (−16.7±6.8 versus −15.4±6.0 cmH2O, p=0.41), but did reduce loop gain (−10.1±2.6 versus −4.4±2.1, p=0.04) and hypercapnic ventilatory responses (7.3±1.2 versus 6.1±1.5 L·min−1, p=0.006).

Concordant with recent clinical findings, 40 mg of MS-Contin does not systematically impair airway collapsibility, pharyngeal muscle responsiveness or the arousal threshold in moderately severe OSA patients. However, consistent with blunted chemosensitivity, ventilatory control is altered.

Association of Opioid and Benzodiazepine Use with Adverse Respiratory Events in Older Adults with Chronic Obstructive Pulmonary Disease

Rationale: Older adults with chronic obstructive pulmonary disease (COPD) are at substantially increased risk for medication-related adverse events. Two frequently prescribed classes of drugs that pose a particular risk to this patient group are opioids and benzodiazepines. Research on this topic has yielded conflicting findings.Objectives: The purpose of this study was to examine, among older adults with COPD, whether: 1) independent or concurrent use of opioid and benzodiazepine medications was associated with hospitalizations for respiratory events, and 2) this association was exacerbated by the presence of obstructive sleep apnea (OSA).Methods: We conducted a case-control study of Medicare beneficiaries aged ≥66 years, who were diagnosed with COPD in 2013, using the 5% national Medicare database. Cases (n = 3,232) were defined as patients hospitalized for a primary COPD-related respiratory diagnosis in 2014 and were matched with up to two control subjects (n = 6,247) on index date, age, sex, socioeconomic status, comorbidity, presence of OSA, COPD medication, and COPD complexity.Results: In comparison to the referent (no opioid or benzodiazepine use), opioid use alone (adjusted odds ratio [aOR], 1.73; 95% confidence interval [CI], 1.52-1.97), benzodiazepine use alone (aOR, 1.42; 95% CI, 1.21-1.66), and concurrent opioid/ benzodiazepine use (aOR, 2.32; 95% CI, 1.94-2.77) in the 30 days before the event/index date were all associated with an increased risk of hospitalization for a respiratory condition. Risk of hospitalization was higher with concurrent opioid and benzodiazepine use when compared with use of either medication alone. There was no statistically significant interaction between OSA and either of the drugs, alone or in combination. However, the adverse respiratory effects of concurrent opioid and benzodiazepine use were increased in patients with a high degree of COPD complexity. All of the above findings persisted using exposure windows that extended to 60 and 90 days before the event/index date.Conclusions: Among older adults with COPD, use of opioid and benzodiazepine medications alone or in combination were associated with increased adverse respiratory events. The adverse effects of these medications were not exacerbated in patients with COPD-OSA overlap syndrome. However, the adverse impact of dual opioid and benzodiazepine was greater in patients with high-complexity COPD.

Effects of morphine on respiratory load detection, load magnitude perception, and tactile sensation in obstructive sleep apnea

Pharyngeal and respiratory sensation is impaired in obstructive sleep apnea (OSA). Opioids may further diminish respiratory sensation. Thus protective pharyngeal neuromuscular and arousal responses to airway occlusion that rely on respiratory sensation could be impaired with opioids to worsen OSA severity. However, little is known about the effects of opioids on upper airway and respiratory sensation in people with OSA. This study was designed to determine the effects of 40 mg of MS-Contin on tactile sensation, respiratory load detection, and respiratory magnitude perception in people with OSA during wakefulness. A double-blind, randomized, crossover design (1 wk washout) was used. Twenty-one men with untreated OSA (apnea/hypopnea index = 26 ± 17 events/h) recruited from a larger clinical study completed the protocol. Tactile sensation using von Frey filaments on the back of the hand, internal mucosa of the cheek, uvula, and posterior pharyngeal wall were not different between placebo and morphine [e.g., median (interquartile range) posterior wall = 0.16 (0.16, 0.4) vs. 0.4 (0.14, 1.8) g, P = 0.261]. Similarly, compared with placebo, morphine did not alter respiratory load detection thresholds for nadir mask pressure detected = −2.05 (−3.37, −1.55) vs. −2.19 (−3.36, −1.41) cmH2O, P = 0.767], or respiratory load magnitude perception [mean ± SD Borg scores during a 5 resistive load (range: 5–126 cmH2O·l−1·s−1) protocol = 4.5 ± 1.6 vs. 4.2 ± 1.2, P = 0.347] but did reduce minute ventilation during quiet breathing (11.4 ± 3.3 vs. 10.7 ± 2.6 l/min, P < 0.01). These findings indicate that 40 mg of MS-Contin does not systematically impair tactile or respiratory sensation in men with mild to moderate, untreated OSA. This suggests that altered respiratory sensation to acute mechanical stimuli is not likely to be a mechanism that contributes to worsening of OSA with a moderate dose of morphine.

NEW & NOTEWORTHY Forty milligrams of MS-Contin does not alter upper airway tactile sensation, respiratory load detection thresholds, or respiratory load magnitude perception in people with obstructive sleep apnea but does decrease breathing compared with placebo during wakefulness. Despite increasing concerns of harm with opioids, the current findings suggest that impaired respiratory sensation to acute mechanical stimuli with this dose of MS-Contin is unlikely to be a direct mechanism contributing to worsening sleep apnea severity in people with mild-to-moderate disease.