Opioids, respiratory depression, and sleep-disordered breathing

Perioperative adverse events in adult patients with obstructive sleep apnea undergoing ambulatory surgery: An updated systematic review and meta-analysis

BACKGROUND

The suitability of ambulatory surgery for patients with obstructive sleep apnea (OSA) remains controversial. This systematic review and meta-analysis aimed to evaluate the odds of perioperative adverse events in patients with OSA undergoing ambulatory surgery, compared to patients without OSA.

METHODS

Four electronic databases were searched for studies published between January 1, 2011 and July 11, 2023. The inclusion criteria were: adult patients with diagnosed or high-risk of OSA undergoing ambulatory surgery; perioperative adverse events; control group included; general and/or regional anesthesia; and publication on/after February 1, 2011. We calculated effect sizes as odds ratios using a random effects model, and additional sensitivity analyses were conducted.

RESULTS

Seventeen studies (375,389 patients) were included. OSA was associated with an increased odds of same-day admission amongst all surgery types (OR 1.94, 95% CI 1.46-2.59, I2:79%, P < 0.00001, 11 studies, n = 347,342), as well as when only orthopedic surgery was considered (OR 2.68, 95% CI 2.05-3.48, I2:41%, P < 0.00001, 6 studies, n = 132,473). Three studies reported that OSA was strongly associated with prolonged post anesthesia care unit (PACU) length of stay (LOS), while one study reported that the association was not statistically significant. In addition, four studies reported that OSA was associated with postoperative respiratory depression/hypoxia, with one large study on shoulder arthroscopy reporting an almost 5-fold increased odds of pulmonary compromise, 5-fold of myocardial infarction, 3-fold of acute renal failure, and 5-fold of intensive care unit (ICU) admission.

CONCLUSIONS

Ambulatory surgical patients with OSA had almost two-fold higher odds of same-day admission compared to non-OSA patients. Multiple large studies also reported an association of OSA with prolonged PACU LOS, respiratory complications, and/or ICU admission. Clinicians should screen preoperatively for OSA, optimize comorbidities, adhere to clinical algorithm-based management perioperatively, and maintain a high degree of vigilance in the postoperative period.

New trends of drug abuse in custodial settings: A systematic review on the misuse of over-the-counter drugs, prescription-only-medications, and new psychoactive substances

The article presents a systematic literature review on the use and the psychiatric implications of over-the-counter drugs (OTC), prescription-only-medications (POM), and new psychoactive substances (NPS) within custodial settings. The searches wer carried out on 2 November 2022 on PubMed, Scopus, and Web of Science in line with PRISMA guidelines. A total of 538 records were identified, of which 37 met the inclusion criteria. Findings showed the most prevalent NPS and OTC and POM classes reported in prisons were synthetic cannabinoids receptor agonists (SCRAs) and opioids, respectively. NPS markets were shown to be in constant evolution following the pace of legislations aimed to reduce their spread. The use of such substances heavily impacts the conditions and rehabilitation of persons in custody, with consequent physical and mental health risks. It is important to raise awareness of the use and misuse of such substances in prisons (i) from an early warning perspective for law enforcement and policy makers (ii) to prompt doctors to cautiously prescribe substances that may be misused (iii) to improve and increase access to treatment provided (iv) to add such substances to routine toxicological screening procedures (v) to improve harm reduction programmes.

Positive Airway Pressure in Surgical Patients with Sleep Apnea: What is the Supporting Evidence?

Obstructive sleep apnea (OSA) is prevalent amongst surgical patients and associated with an increased incidence of perioperative complications. The gold standard treatment for moderate-to-severe OSA is positive airway pressure (PAP) therapy. Practice guidelines by the American Society of Anesthesiologists and the Society of Anesthesia and Sleep Medicine have recommended preoperative screening for OSA and consideration of initiation of PAP therapy for patients with severe OSA. These guidelines, developed mainly by the consensus of experts, highlight the adverse impact of OSA on postoperative outcomes and recommend the use of postoperative PAP in surgical patients with moderate to severe OSA. Since the development of these guidelines, there has been an increase in the number of publications regarding the efficacy of PAP therapy in surgical patients with OSA. Our review provides an update on the existing literature on the efficacy of PAP therapy in surgical patients with OSA. We focus on the postoperative complications associated with OSA, potential mechanisms leading to the increased risk of postoperative adverse events, and summarize the perioperative guidelines for the management of patients with OSA, evidence supporting perioperative PAP therapy, as well as limitations to PAP therapy and alternatives. An update on the existing literature of the efficacy of PAP therapy in surgical patients with OSA is critical to assess the impact of prior guidelines, determine when and how to effectively implement PAP therapy, and target barriers to PAP adherence in the perioperative setting.

Orexin receptor 2 agonist activates diaphragm and genioglossus muscle through stimulating inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons in rodents

Orexin-mediated stimulation of orexin receptors 1/2 (OX[1/2]R) may stimulate the diaphragm and genioglossus muscle via activation of inspiratory neurons in the pre-Bötzinger complex, which are critical for the generation of inspiratory rhythm, and phrenic and hypoglossal motoneurons. Herein, we assessed the effects of OX2R-selective agonists TAK-925 (danavorexton) and OX-201 on respiratory function. In in vitro electrophysiologic analyses using rat medullary slices, danavorexton and OX-201 showed tendency and significant effect, respectively, in increasing the frequency of inspiratory synaptic currents of inspiratory neurons in the pre-Bötzinger complex. In rat medullary slices, both danavorexton and OX-201 significantly increased the frequency of inspiratory synaptic currents of hypoglossal motoneurons. Danavorexton and OX-201 also showed significant effect and tendency, respectively, in increasing the frequency of burst activity recorded from the cervical (C3-C5) ventral root, which contains axons of phrenic motoneurons, in in vitro electrophysiologic analyses from rat isolated brainstem-spinal cord preparations. Electromyogram recordings revealed that intravenous administration of OX-201 increased burst frequency of the diaphragm and burst amplitude of the genioglossus muscle in isoflurane- and urethane-anesthetized rats, respectively. In whole-body plethysmography analyses, oral administration of OX-201 increased respiratory activity in free-moving mice. Overall, these results suggest that OX2R-selective agonists enhance respiratory function via activation of the diaphragm and genioglossus muscle through stimulation of inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons. OX2R-selective agonists could be promising drugs for various conditions with respiratory dysfunction.

Cannabinoid Analgesia in Postoperative Pain Management: From Molecular Mechanisms to Clinical Reality

Postoperative pain (POP) is a challenging clinical phenomenon that affects the majority of surgical patients and demands effective management to mitigate adverse outcomes such as persistent pain. The primary goal of POP management is to alleviate suffering and facilitate a seamless return to normal function for the patient. Despite compelling evidence of its drawbacks, opioid analgesia remains the basis of POP treatment. Novel therapeutic approaches rely on multimodal analgesia, integrating different pharmacological strategies to optimize efficacy while minimizing adverse effects. The recognition of the imperative role of the endocannabinoid system in pain regulation has prompted the investigation of cannabinoid compounds as a new therapeutic avenue. Cannabinoids may serve as adjuvants, enhancing the analgesic effects of other drugs and potentially replacing or at least reducing the dependence on other long-term analgesics in pain management. This narrative review succinctly summarizes pertinent information on the molecular mechanisms, clinical therapeutic benefits, and considerations associated with the plausible use of various cannabinoid compounds in treating POP. According to the available evidence, cannabinoid compounds modulate specific molecular mechanisms intimately involved in POP. However, only two of the eleven clinical trials that evaluated the efficacy of different cannabinoid interventions showed positive results.

Respiratory Depression Following Intraoperative Methadone: A Retrospective Cohort Study

BACKGROUND

Methadone is used as a perioperative analgesic in the management of postoperative pain. Despite positive outcomes from randomized trials favoring methadone, concerns about its safety persist, particularly regarding respiratory depression (RD) and excessive sedation. In this study, we compared the incidence of naloxone administration between patients administered intraoperative methadone and those administered intraoperative morphine as a measure of severe RD. Time spent at the postanesthesia care unit (PACU) was used as a proxy variable for excessive sedation.

METHODS

This was a retrospective cohort study including all patients aged ≥18 years who underwent surgery between March 2019 and March 2023 at Aarhus University Hospital, Denmark. We assessed the association between intraoperative administration of either methadone or morphine and postoperative naloxone administration within the first 24 hours using logistic regression (primary outcome). An analogous linear regression model was used for the secondary outcome of time spent in the PACU after surgery. Patients were weighted using propensity scores to adjust for potential confounding variables.

RESULTS

A total of 14,522 patients were included in the analysis. Among the 2437 patients who received intraoperative methadone, 15 (0.62%) patients received naloxone within the first 24 hours after surgery compared to 68 of 12,0885 (0.56%) who received intraoperative morphine. No statistical difference was observed in the odds of naloxone administration between patients administered methadone or morphine (adjusted odds ratio 95% confidence interval [CI], 1.21 [0.40-2.02]). Patients who were administered intraoperative methadone had a mean PACU length of stay (LOS) of 334 minutes (standard deviation [SD], 382) compared to 195 minutes (SD, 228) for those administered intraoperative morphine. The adjusted PACU LOS of patients administered intraoperative methadone was 26% longer compared to those administered intraoperative morphine (adjusted ratio of the geometric means 95% CI, 1.26 [1.22-1.31]).

CONCLUSIONS

The incidence of naloxone administration to treat severe RD was low. No difference was observed in the odds of naloxone administration to treat severe RD between patients administered intraoperative methadone or intraoperative morphine. Intraoperative methadone was associated with longer stays at the PACU; however, this result should be interpreted with care. Our findings suggest that intraoperative methadone has a safety profile comparable to that of morphine with regard to severe RD.

Opioid-free anesthesia using a combination of ketamine and dexmedetomidine in patients undergoing laparoscopic cholecystectomy: a randomized controlled trial

BACKGROUND

Opioids administered as bolus doses or continuous infusions are widely used for major and daycare surgeries. Opioid-free anesthesia is multimodal anesthesia and analgesia that does not use opioids, benefiting patients from opioid-related adverse effects. We compared the postoperative analgesic requirements of patients scheduled for elective laparoscopic cholecystectomy under opioid-free and opioid-based anesthesia.

METHODS

Study included 88 patients aged 18-60 years with American Society of Anesthesiologists physical status 1 and 2 who underwent elective laparoscopic cholecystectomy. Participants were randomly divided into two groups with 44 in each. The opioid-free group was administered an intravenous bolus of ketamine and dexmedetomidine, whereas fentanyl was used in opioid group. Primary outcome was to compare the total amount of fentanyl consumed by both groups during 6 h postoperative period. Episodes of postoperative nausea and vomiting (PONV) and vital signs were noted throughout the postoperative period to analyze the secondary outcomes.

RESULTS

Both groups had similar demographic characteristics. The opioid-free group required lesser analgesia within the first 2 h (61.4 ± 17.4 vs. 79.0 ± 19.4 of fentanyl, P < 0.001), which was statistically significant. However, fentanyl consumption was comparable between the groups at 6 h (152 ± 28.2 vs. 164 ± 33.4, P = 0.061). Compared with 4.5% of the participants in the opioid-free group, 34% of those in the opioid-based group developed moderate PONV.

CONCLUSIONS

Opioid-free anesthesia in patients undergoing laparoscopic cholecystectomy reduced the requirement of analgesia in first two-hour postoperative period and was associated with decreased PONV.

Challenges of acute pain management in older patients

Adequate management of acute pain in the older population is crucial. However, it is inherently complex because of multiple physiological changes that significantly impact both the pharmacokinetics and pharmacodynamics of medications. Current guidelines promote paracetamol as the first-line analgesic for acute pain in older adults, whereas opioids are advised cautiously for moderate to severe acute pain. However, opioids come with a significant array of side effects, which can be more pronounced in older individuals. Ketamine administered via intranasal (IN) and nebulised inhalation in the emergency department for managing acute pain in older patients shows promising potential for improving pain management and reducing opioid reliance Kampan, Thong-on, Sri-on (2024, Age Ageing, 53, afad255). Nebulised ketamine appears superior in terms of adverse event incidence. However, the adoption of IN or nebulised ketamine in older adult acute pain management remains unclear because of the lack of definitive conclusions and clear guidelines. Nevertheless, these modalities can be valuable options for patients where opioid analgesics are contraindicated or when intravenous morphine titration is impractical or contraindicated. Here, we review these concepts, the latest evidence and propose avenues for research.

Artificial intelligent patient-controlled intravenous analgesia improves the outcomes of older patients with laparoscopic radical resection for colorectal cancer

METHODS

Patients undergoing elective laparoscopic radical resection of colorectal cancer from July 2019 to May 2021 were selected. The patients were assigned to Ai-PCIA group and control group. Ai-PCIA group received postoperative analgesia management and effect evaluation through intelligent wireless analgesia system + postoperative follow-up twice a day, while control group received analgesia management and effect evaluation through ward physician feedback + postoperative follow-up twice a day. The pain numerical score (NRS), Richards-Campbell Sleep Scale (RCSQ), and adverse outcomes were collected and compared.

RESULTS

A total of 60 patients (20 females and 40 males with average (78.26 ± 6.42) years old) were included. The NRS scores at rest and during activity of the Ai-PCA group at 8, 12, and 24 h after the operation were significantly lower than that of the control group (all P < 0.05). The RCSQ score of Ai-PCA group was significantly higher than that of control group on the 1st and 2nd days after operation (all P < 0.05). There were no significant differences in the incidence of dizziness and nausea, vomiting, and myocardial ischemia (all P > 0.05).

CONCLUSIONS

Ai-PCIA can improve the analgesic effect and sleep quality of older patients after laparoscopic radical resection, which may be promoted in clinical analgesia practice.

Association Between Pharmacotherapy and Sleep Quality in Patients with Chronic Orofacial and Chronic Body Pain: A Cross-Sectional Study

Purpose

Sleep impairment is associated with many chronic pain disorders. While there is an association between chronic pain and sleep disturbances, little is known about the influence of pharmacotherapy for chronic pain conditions, particularly chronic opioid therapy, on sleep. This study aimed to 1) compare the sleep quality (SQ) in patients with two different pain conditions-chronic body pain and chronic orofacial pain; 2) assess the correlation of SQ and pain intensity; and 3) evaluate the association between pharmacotherapy and SQ.

Patients and Methods

The Pittsburgh Sleep Quality Index (PSQI) was used to measure the SQ in subjects with 1) chronic body pain (n = 100) and 2) chronic orofacial pain (n = 100). The visual analogue scale was applied for pain intensity rating. All subjects were adults recruited at Massachusetts General Hospital, United States. The subjects' demographic data, pain intensity, diagnosis and concurrent use of medications were extracted from their electronic medical records (EMR). Statistical analyses were performed using T-test and Pearson correlation coefficient.

Results

Among 200 subjects (mean age 51.01 ± 15.52 years), 141 (70.5%) were females. PSQI and pain intensity were statistically significantly different between the two groups (p < 0.05 and p < 0.0001, respectively) and higher in subjects with chronic body pain. There was a positive correlation between PSQI and pain intensity (chronic orofacial pain r = 0.3535, p = 0.0004; chronic body pain: r = 0.2247, p < 0.026). PSQI was higher in chronic orofacial pain subjects utilizing opioids and benzodiazepines (PSQI = 15.25).

Conclusion

Chronic pain impairs SQ, which is noticeably worse in subjects with body pain conditions. In addition, pain intensity was correlated with poorer SQ, which in turn was linked to the concomitant use of opioid and benzodiazepine therapy in chronic orofacial pain.

Ability of the integrated pulmonary index to predict impending respiratory events in the early postoperative period

BACKGROUND

In the early postoperative period, respiratory compromise is a significant problem. Standard-of-care monitoring includes respiratory rate (RR) and pulse oximetry, which are helpful; however, low SpO₂ is often a late sign during decompensation. The FDA-approved Capnostream-20p monitor records four variables (SpO₂, RR, End-tidal CO₂, heart rate), which are combined by fuzzy logic into a single, unit-less value (range 1-10) called the integrated pulmonary index (IPI). No published studies have assessed the performance of a low IPI to predict impending respiratory events.

METHODS

In this investigator-initiated study, adult patients undergoing general anesthesia were monitored with the Capnostream-20p monitor for up to 2 h during their recovery room stay. The study coordinator, who along with clinicians, was blinded to IPI values, recorded the time of any respiratory event, defined a priori as any one of eight respiratory-related interventions/conditions. The primary sensitivity endpoint (early detection success) was defined as at least 80% of events predicted by at least 2 consecutive low IPI (≤ 7) values within 2-15 min before an event occurred. Late detection was defined as low IPI values occurring with 2 min prior to or 2 min after the event occurred.

DISCUSSION

Of 358 patients, ≥ 1 respiratory event occurred in 183 (51.1%) patients. Of 802 total events, 606 were detected early (within 2-15 min prior to the event), and 653 were detected either early or late. Therefore, the sensitivity for early detection was 75.6% (95% confidence interval [CI]: 72.6-78.5%), which differed significantly from the 80% sensitivity goal by 4.4% (p = 0.0016). Sensitivity for total success (early or late) was 81.4% (95% CI: 78.7-84.1%), which was significantly different from the 90% on time sensitivity goal by 8.6% (p < 0.0001).

CONCLUSIONS

A low IPI was 75.6% sensitive for early detection (within 2-15 min) prior to respiratory events but did not achieve our preset threshold of 80% for success.

Perioperative opioids: a narrative review contextualising new avenues to improve prescribing

Opioids have dominated the management of perioperative pain in recent decades with higher doses than ever before used in some circumstances. Through the expanding use of opioids, growing research has highlighted their associated side-effects and the intertwined phenomena of acute withdrawal syndrome, opioid tolerance, and opioid-induced hyperalgesia. With multiple clinical guidelines now endorsing multimodal analgesia, a diverse array of opioid-sparing agents emerges and has been studied to variable degrees, including techniques of opioid-free anaesthesia. It remains unclear to what extent such methods should be adopted, yet current evidence does suggest dependence on opioids as the primary perioperative analgesic might not meet the principles of 'rational prescribing' as described by Maxwell. In this narrative review we describe how, using current evidence, a patient-centred rational-prescribing approach can be applied to opioids in the perioperative period. To contextualise this approach, we discuss the historical adoption of opioids in anaesthesia, our growing understanding of associated side-effects and emerging strategies of opioid-sparing and opioid-free anaesthesia. We discuss avenues and challenges for improving opioid prescribing to limit persistent postoperative opioid use and how these may be incorporated into a rational-prescribing approach.

βγ G-proteins, but not regulators of G-protein signaling 4, modulate opioid-induced respiratory rate depression

Opioid medications are the mainstay of pain management but present substantial side-effects such as respiratory depression which can be lethal with overdose. Most opioid drugs, such as fentanyl, act on opioid receptors such as the G-protein-coupled µ-opioid receptors (MOR). G-protein-coupled receptors activate pertussis toxin-sensitive G-proteins to inhibit neuronal activity. Binding of opioid ligands to MOR and subsequent activation G proteins βγ is modulated by regulator of G-protein signaling (RGS). The roles of G-proteins βγ and RGS in MOR-mediated inhibition of the respiratory network are not known. Using rodent models to pharmacologically modulate G-protein signaling, we aim to determine the roles of βγ G-proteins and RGS4. We showed that inhibition of βγ G-proteins using gallein perfused in the brainstem circuits regulating respiratory depression by opioid drugs results in complete reversal of respiratory depression. Blocking of RGS4 using CCG55014 did not change the respiratory depression induced by MOR activation despite co-expression of RGS4 and MORs in the brainstem. Our results suggest that neuronal inhibition by opioid drugs is mediated by G-proteins, but not by RGS4, which supports the concept that βγ G-proteins could be molecular targets to develop opioid overdose antidotes without the risks of re-narcotization often found with highly potent opioid drugs. On the other hand, RGS4 mediates opioid analgesia, but not respiratory depression, and RGS4 may be molecular targets to develop pain therapies without respiratory liability.

Balancing Safety, Comfort, and Fall Risk: An Intervention to Limit Opioid and Benzodiazepine Prescriptions for Geriatric Patients

Introduction

This study reports on the impact of a clinical decision support tool embedded in the electronic medical record and characterizes the demographics, prescribing patterns, and risk factors associated with opioid and benzodiazepine misuse in the older adult population.

Significance

This study reports on prescribing patterns for patients ≥65 years-old who presented to Emergency Departments (ED) or Urgent Care (UC) facilities across a large healthcare system following a fall (n = 34,334 encounters; n = 25,469 patients). This system implemented a clinical decision support intervention which provides an alert when the patient has an evidence-based risk factor for prescription drug misuse; prescribers can continue, amend or cancel the prescription.

Results

Of older adults presenting with a fall, 31.4% (N = 7986) received an opioid or benzodiazepine prescription. Women and younger patients (65-74) had a higher likelihood of receiving a prescription (P < .0001). 11% had ≥1 risk factor. Women were more likely to receive an early refill (P = .0002) and younger (65-74) men were more likely to have a past positive toxicology (P < .0001). A prescription was initiated in 8,591 encounters, and 946 (9.0%) triggered an alert. In 58 cases, the alert resulted in a prescription modification, and in 80 the prescription was canceled.

Conclusions

Documented risk for opioid misuse in the elderly was 10% among patients presenting to the ED/UC after a fall. The dangers associated with opioid/benzodiazepine use increase with age as does fall risk. Awareness of risk factors is an important first step; more work is needed to address potentially hazardous prescriptions in this population.

Error traps in acute pain management in children

Providing effective acute pain management to hospitalized children can help improve outcomes, decrease length of stay, and increase patient and parental satisfaction. Error traps (circumstances that lead to erroneous actions or undesirable consequences) can result in inadequately controlled pain, unnecessary side effects, and adverse events. This article highlights five error traps encountered when managing acute pain in children. They include failure to appropriately assess pain, optimally utilize regional anesthesia, select suitable systemic analgesics, identify and treat medication-related side effects, and consider patient characteristics when choosing medication or dosing route. These issues are easily addressed when the clinician is cognizant of ways to anticipate, identify, and mitigate or avoid these errors.

Impact of Opioid-Free Anesthesia on Analgesia and Recovery Following Bariatric Surgery: a Meta-Analysis of Randomized Controlled Studies

This meta-analysis aimed at exploring the impact of opioid-free anesthesia (OFA) on pain score and opioid consumption in patients undergoing bariatric surgery (BS). Literature search identified eight eligible trials. Forest plot revealed a significantly lower pain score (mean difference (MD) =  - 0.96, p = 0.0002; 318 patients), but not morphine consumption (MD =  - 5.85 mg, p = 0.1; 318 patients) at postoperative 24 h in patients with OFA than in those without. Pooled analysis also showed a lower pain score (p = 0.002), morphine consumption (p = 0.0003) in the postanesthetic care unit, and risk of postoperative nausea/vomiting (p = 0.0003) in the OFA group compared to the controls. In conclusion, this meta-analysis demonstrated that opioid-free anesthesia improved pain outcomes immediately and at 24 h after surgery without a beneficial impact on opioid consumption at postoperative 24 h. KEY POINTS: • Roles of opioid-free anesthesia (OFA) in bariatric surgery (BS) were investigated. • Outcomes included postoperative pain score, opioid use, and nausea/vomiting risk. • OFA was associated with lower 24-h pain score but not opioid consumption. • Lower pain score and opioid consumption were noted in the postanesthetic care unit. • OFA correlated with a lower risk of postoperative nausea/vomiting.

S-Nitroso-L-Cysteine Stereoselectively Blunts the Deleterious Effects of Fentanyl on Breathing While Augmenting Antinociception in Freely-Moving Rats

Endogenous and exogenously administered S-nitrosothiols modulate the activities of central and peripheral systems that control breathing. We have unpublished data showing that the deleterious effects of morphine on arterial blood-gas chemistry (i.e., pH, pCO2, pO2, and sO2) and Alveolar-arterial gradient (i.e., index of gas exchange) were markedly diminished in anesthetized Sprague Dawley rats that received a continuous intravenous infusion of the endogenous S-nitrosothiol, S-nitroso-L-cysteine. The present study extends these findings by showing that unanesthetized adult male Sprague Dawley rats receiving an intravenous infusion of S-nitroso-L-cysteine (100 or 200 nmol/kg/min) markedly diminished the ability of intravenous injections of the potent synthetic opioid, fentanyl (10, 25, and 50 μg/kg), to depress the frequency of breathing, tidal volume, and minute ventilation. Our study also found that the ability of intravenously injected fentanyl (10, 25, and 50 μg/kg) to disturb eupneic breathing, which was measured as a marked increase of the non-eupneic breathing index, was substantially reduced in unanesthetized rats receiving intravenous infusions of S-nitroso-L-cysteine (100 or 200 nmol/kg/min). In contrast, the deleterious effects of fentanyl (10, 25, and 50 μg/kg) on frequency of breathing, tidal volume, minute ventilation and non-eupneic breathing index were fully expressed in rats receiving continuous infusions (200 nmol/kg/min) of the parent amino acid, L-cysteine, or the D-isomer, namely, S-nitroso-D-cysteine. In addition, the antinociceptive actions of the above doses of fentanyl as monitored by the tail-flick latency assay, were enhanced by S-nitroso-L-cysteine, but not L-cysteine or S-nitroso-D-cysteine. Taken together, these findings add to existing knowledge that S-nitroso-L-cysteine stereoselectively modulates the detrimental effects of opioids on breathing, and opens the door for mechanistic studies designed to establish whether the pharmacological actions of S-nitroso-L-cysteine involve signaling processes that include 1) the activation of plasma membrane ion channels and receptors, 2) selective intracellular entry of S-nitroso-L-cysteine, and/or 3) S-nitrosylation events. Whether alterations in the bioavailability and bioactivity of endogenous S-nitroso-L-cysteine is a key factor in determining the potency/efficacy of fentanyl on breathing is an intriguing question.

Opioid-Use, COVID-19 Infection, and Their Neurological Implications

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an imminent threat to human health and public safety. ACE2 and transmembrane serine protease 2 proteins on host cells provide the viral entry point to SARS-CoV-2. Although SARS-CoV-2 mainly infects the respiratory system, there have been reports of viral neurotropism and central nervous system injury as indicated by plasma biomarkers, including neurofilament light chain protein and glial fibrillary acidic protein. Even with a small proportion of infections leading to neurological manifestation, the overall number remains high. Common neurological manifestations of SARS-CoV-2 infection include anosmia, ageusia, encephalopathy, and stroke, which are not restricted to only the most severe infection cases. Opioids and opioid antagonists bind to the ACE2 receptor and thereby have been hypothesized to have therapeutic potential in treating COVID-19. However, in the case of other neurotropic viral infections such as human immunodeficiency virus (HIV), opioid use has been established to exacerbate HIV-mediated central nervous system pathogenesis. An analysis of electronic health record data from more than 73 million patients shows that people with Substance Use Disorders are at higher risk of contracting COVID-19 and suffer worse consequences then non-users. Our in-vivo and in-vitro unpublished studies show that morphine treatment causes increased expression of ACE2 in murine lung and brain tissue as early as 24 h post treatment. At the same time, we also observed morphine and lipopolysaccharides treatment lead to a synergistic increase in ACE2 expression in the microglial cell line, SIM-A9. This data suggests that opioid treatment may potentially increase neurotropism of SARS-CoV-2 infection. We have previously shown that opioids induce gut microbial dysbiosis. Similarly, gut microbiome alterations have been reported with SARS-CoV-2 infection and may play a role in predicting COVID-19 disease severity. However, there are no studies thus far linking opioid-mediated dysbiosis with the severity of neuron-specific COVID-19 infection.

Shoulder Surgery as an Effective Treatment for Shoulder-Related Sleep Disturbance: A Systematic Review

PURPOSE

The purpose of this systematic review is to evaluate the current literature in an effort to investigate sleep quality and disturbances and the association with clinical outcomes of patients undergoing shoulder surgery.

METHODS

A systematic review of the PubMed, Embase, and Cochrane Library databases was performed according to PRISMA guidelines. All English-language literature reporting clinical outcomes and sleep quality and disturbance after shoulder surgery was reviewed by 2 independent reviewers. Outcomes assessed included patient-reported outcomes (PROs) and sleep quality. Specific PROs included the Pittsburgh Sleep Quality Index (PSQI), Visual Analog Scale (VAS) for pain, Simple Shoulder Test (SST), University of California Los Angeles (UCLA) Shoulder Rating Scale, and American Shoulder and Elbow Surgeons Score (ASES). Study methodology was assessed using the Modified Coleman Methodology Score. Descriptive statistics are presented.

RESULTS

Sixteen studies (11 level IV, 2 level III, 3 level II) with a total of 2748 shoulders were included (age, 12-91 years; follow-up, 0.25-132 months). In total, 2198 shoulders underwent arthroscopic rotator cuff repair (RCR), 131 shoulders underwent arthroscopic capsular release, 372 shoulders underwent total shoulder arthroplasty (TSA), 18 shoulders underwent comprehensive arthroscopic management, and 29 shoulders underwent sternoclavicular joint procedures. All shoulder surgeries improved self-reported sleep and PROs from before to after surgery. In RCR patients, PSQI scores were significantly associated with VAS scores, SST scores (r = 0.453, r = -0.490, P < .05, respectively), but not significantly associated with UCLA Shoulder rating scale or the ASES scores (r = 0.04, r = 0.001, P > .05, respectively). In TSA patients, PSQI scores were significantly associated with ASES scores (r = -0.08, P < .05). All 4 RCR studies and 1 TSA study using PSQI found significant improvements in mean PSQI scores within 6 to 24 months (P < .05).

CONCLUSIONS

Surgical intervention for rotator cuff tear and glenohumeral osteoarthritis significantly improves self-reported sleep in patients with shoulder pain. However, there remains a dearth of available studies assessing the effects of surgical intervention for adhesive capsulitis, sternoclavicular joint instability, and sternoclavicular osteoarthritis on sleep. Future studies should use sleep-specific PROs and quantitative measures of sleep to further elucidate the relationship between sleep and the effect of shoulder surgery.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

A Retrospective Review of Opioid Prescribing Practices for At-Risk Pediatric Populations Undergoing Ambulatory Surgery

OBJECTIVE

Pediatric patients with sleep-disordered breathing (SDB) and obesity are at risk for opioid-induced respiratory depression. Although monitoring in the inpatient setting allows for early recognition of opioid-related adverse events, there is far less vigilance after ambulatory surgery as patients are discharged home. Guidelines for proper opioid dosing in these pediatric subsets have not been established. We sought to determine if at-risk children were more likely to receive doses of opioids outside the recommended range.

METHODS

Baseline opioid prescribing data for all outpatient surgery patients receiving an opioid prescription between January 2019 and June 2020 were retrospectively reviewed. Patients with SDB or obesity were identified. To obtain more information about prescribing practices, we analyzed patient demographics, size descriptors used for calculations, and prescription characteristics (dose, duration, and prescribing surgical service).

RESULTS

A total of 4674 patients received an opioid prescription after outpatient surgery. Of those, 173 patients had SDB and 128 were obese. Surgical subspecialties rendering most of the opioid prescriptions included otolaryngology and orthopedics. Obese patients were more likely (64%) to be prescribed opioids using ideal weight at higher mg/kg doses (>0.05 mg/kg; 83.3%; p < 0.0001). When providers used actual body weight, lower mg/kg doses were more likely to be used (53.7%; p < 0.0001). No prescriptions used lean body mass.

CONCLUSIONS

Overweight/obese children were more likely to receive opioid doses outside the recommended range. Variability in prescribing patterns demonstrates the need for more detailed guidelines to minimize the risk of opioid-induced respiratory complications in vulnerable pediatric populations.

Dynamic Rhythmogenic Network States Drive Differential Opioid Responses in the In Vitro Respiratory Network

Death from opioid overdose is typically caused by opioid-induced respiratory depression (OIRD). A particularly dangerous characteristic of OIRD is its apparent unpredictability. The respiratory consequences of opioids can be surprisingly inconsistent, even within the same individual. Despite significant clinical implications, most studies have focused on average dose-r esponses rather than individual variation, and there remains little insight into the etiology of this apparent unpredictability. The preBötzinger complex (preBötC) in the ventral medulla is an important site for generating the respiratory rhythm and OIRD. Here, using male and female C57-Bl6 mice in vitro, we demonstrate that the preBötC can assume different network states depending on the excitability of the preBötC and the intrinsic membrane properties of preBötC neurons. These network states predict the functional consequences of opioids in the preBötC, and depending on network state, respiratory rhythmogenesis can be either stabilized or suppressed by opioids. We hypothesize that the dynamic nature of preBötC rhythmogenic properties, required to endow breathing with remarkable flexibility, also plays a key role in the dangerous unpredictability of OIRD.SIGNIFICANCE STATEMENT Opioids can cause unpredictable, life-threatening suppression of breathing. This apparent unpredictability makes clinical management of opioids difficult while also making it challenging to define the underlying mechanisms of OIRD. Here, we find in brainstem slices that the preBötC, an opioid-sensitive subregion of the brainstem, has an optimal configuration of cellular and network properties that results in a maximally stable breathing rhythm. These properties are dynamic, and the state of each individual preBötC network relative to the optimal configuration of the network predicts how vulnerable rhythmogenesis is to the effects of opioids. These insights establish a framework for understanding how endogenous and exogenous modulation of the rhythmogenic state of the preBötC can increase or decrease the risk of OIRD.

A new side-effect of sufentanil: increased monocyte-endothelial adhesion

BACKGROUND

Opioids have been identified by the World Health Organization to be 'indispensable for the relief of pain and suffering'. Side-effects, such as nausea, vomiting, postoperative delirium, and effects on breathing, of opioids have been well investigated; however, the influence of opioids on monocyte-endothelial adherence has never been reported. Therefore, we explored the effects of representative opioids, fentanyl, sufentanil, and remifentanil, on monocyte-endothelial adherence and the underlying mechanisms.

METHODS

We built a cell adhesion model with U937 monocytes and human umbilical vein endothelial cells (HUVECs). Two kinds of connexin43 (Cx43) channel inhibitors, 18-α-GA and Gap 27, were used to alter Cx43 channel function in U937 monocytes and HUVECs, respectively, to determine the effects of Cx43 channels on U937-HUVEC adhesion. Subsequently, the effects of fentanyl, sufentanil and remifentanil on Cx43 channel function and U937-HUVEC adhesion were explored.

RESULTS

When fentanyl, sufentanil and remifentanil acted on monocytes or endothelial cells, their effects on monocyte-endothelial adherence differed. When acting on U937 monocytes, sufentanil significantly increased U937-HUVEC adhesion which was associated with reduced release of ATP from Cx43 channels, while fentanyl and remifentanil did not have these influences. Although sufentanil could also inhibit Cx43 channel function in HUVECs, it had no effect on ATP release from HUVECs or U937-HUVECs adhesion.

CONCLUSIONS

We demonstrated that sufentanil application increases monocyte-endothelial adherence which was associated with reduced release of ATP from Cx43 channels in monocytes. This side-effect of sufentanil should be considered seriously by clinicians.

Monitoring postoperative lung recovery using electrical impedance tomography in post anesthesia care unit: an observational study

With electrical impedance tomography (EIT) recruitment and de-recruitment phenomena can be quantified and monitored at bedside. The aim was to examine the feasibility of EIT with respect to monitor atelectasis formation and resolution in the post anesthesia care unit (PACU). In this observational study, 107 postoperative patients were investigated regarding the presence and recovery of atelectasis described by the EIT-derived parameters Global Inhomogeneity Index (GI Index), tidal impedance variation (TIV), and the changes in end-expiratory lung impedance (ΔEELI). We examined whether the presence of obesity (ADP group) has an influence on pulmonary recovery compared to normal weight patients (NWP group). During the stay at PACU, measurements were taken every 15 min. GI Index, TIV, and ΔEELI were calculated for each time point. 107 patients were monitored and EIT-data of 16 patients were excluded for various reasons. EIT-data of 91 patients were analyzed off-line. Their length of stay averaged 80 min (25th and 75th quartile 52–112). The ADP group demonstrated a significantly higher GI Index at PACU arrival (p < 0.001). This finding disappeared during their stay at the PACU. Additionally, the ADP group showed a significant increase in ΔEELI between PACU arrival and discharge (p = 0.025). Furthermore, TIV showed a significantly lower value during the first 90 min of PACU stay as compared to the time period thereafter (p = 0.036). Our findings demonstrate that obesity has an influence on intraoperative atelectasis formation and de-recruitment during PACU stay. The application of EIT in spontaneously breathing PACU patients seems meaningful in monitoring pulmonary recovery.

Simple screening model for identifying the risk of sleep apnea in patients on opioids for chronic pain

BACKGROUND

There is an increased risk of sleep apnea in patients using opioids for chronic pain. We hypothesized that a simple model comprizing of: (1) STOP-Bang questionnaire and resting daytime oxyhemoglobin saturation (SpO₂); and (2) overnight oximetry will identify those at risk of moderate-to-severe sleep apnea in patients with chronic pain.

METHOD

Adults on opioids for chronic pain were recruited from pain clinics. Participants completed the STOP-Bang questionnaire, resting daytime SpO₂, and in-laboratory polysomnography. Overnight oximetry was performed at home to derive the Oxygen Desaturation Index. A STOP-Bang score ≥3 or resting daytime SpO₂ ≤95% were used as thresholds for the first step, and for those identified at risk, overnight oximetry was used for further screening. The Oxygen Desaturation Index from overnight oximetry was validated against the Apnea-Hypopnea Index (≥15 events/hour) from polysomnography.

RESULTS

Of 199 participants (52.5±12.8 years, 58% women), 159 (79.9%) had a STOP-Bang score ≥3 or resting SpO₂ ≤95% and entered the second step (overnight oximetry). Using an Oxygen Desaturation Index ≥5 events/hour, the model had a sensitivity of 86.4% and specificity of 52% for identifying moderate-to-severe sleep apnea. The number of participants who would require diagnostic sleep studies was decreased by 38% from Step 1 to Step 2 of the model.

CONCLUSION

A simple model using STOP-Bang questionnaire and resting daytime SpO₂, followed by overnight oximetry, can identify those at high risk of moderate-to-severe sleep apnea in patients using opioids for chronic pain.

TRIAL REGISTRATION NUMBER

NCT02513836.

Treatment for patients with sleep apnea on opioids for chronic pain: results of the OpSafe trial

STUDY OBJECTIVES

Approximately 20% of North Americans are afflicted with chronic pain with 3% being opioid users. The objective was to determine whether patients on opioids for chronic pain with newly diagnosed sleep apnea attended sleep clinic review and followed treatment recommendations.

METHODS

The study was a post hoc analysis from a multicenter perspective cohort study. Inclusion criteria included adults taking opioid medications for chronic pain for >3 months. Demographic data and daily opioid dose were collected. Sleep apnea was diagnosed via level 1 polysomnography. Patients who attended sleep clinic review were grouped based on the types of treatment they received.

RESULTS

A total of 204 patients completed polysomnography and 58.8% were diagnosed to have sleep apnea (apnea-hypopnea index ≥5 events/h). Of those with sleep apnea, 58% were recommended to have an evaluation by a sleep physician. Body mass index and age were 29.5 ± 6 kg/m² and 56 ± 12 years, respectively. Of those with newly diagnosed sleep apnea, 25% received treatment, with the majority being treated with positive airway pressure therapy, whereas the rest received positional therapy and opioids/sedative reduction. The adherence rate of positive airway pressure therapy was 55% at 1 year. Over 50% of participants on opioids for chronic pain with newly diagnosed sleep apnea declined attendance for sleep clinic review or treatment.

CONCLUSIONS

There was a high refusal rate to attend clinic for treatment. Adherence to positive airway pressure therapy was low at 55%. This sheds light on the high rate of treatment nonadherence and the need for further research.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Opioid Safety Program in Pain Clinics (Op-Safe); URL: https://www.clinicaltrials.gov/ct2/show/NCT02513836; Identifier: NCT02513836.

Predictive Performance of Oximetry to Detect Sleep Apnea in Patients Taking Opioids

BACKGROUND

Long-term use of opioids for treatment of chronic pain is associated with significant risks including worsening unrecognized or untreated sleep apnea that may increase morbidity and mortality. Overnight oximetry has been validated for predicting sleep apnea in surgical and sleep clinic patients. The objective of the study was to assess the predictive accuracy of oxygen desaturation index (ODI 4%) from home overnight oximetry when compared to apnea hypopnea index (AHI) from polysomnography for predicting sleep apnea in patients taking opioids for chronic pain.

METHODS

This was a planned post hoc analysis of a prospective cohort study conducted at 5 pain clinics. Patient characteristics and daily morphine milligram equivalent (MME) dose were recorded. All consented patients underwent home overnight oximetry (PULSOX-300i, Konica Minolta Sensing, Inc, Osaka, Japan) and in-laboratory polysomnography. The predictive performance of ODI 4% from oximetry was assessed against AHI from polysomnography.

RESULTS

Among 332 consented patients, 181 with polysomnography and overnight oximetry data were analyzed. The mean age and body mass index of 181 patients were 52 ± 13 years and 29 ± 6 kg/m2, respectively, with 40% men. The area under the receiver operating curve for ODI to predict moderate-to-severe sleep apnea (AHI ≥15 events/h) and severe sleep apnea (AHI ≥30 events/h) was 0.82 (95% confidence interval [CI], 0.75-0.88) and 0.87 (95% CI, 0.80-0.94). ODI ≥5 events/h had a sensitivity of 85% (95% CI, 74-92) and specificity of 57% (95% CI, 52-61) to predict moderate-to-severe sleep apnea. ODI ≥15 events/h had a sensitivity of 71% (95% CI, 55-83) and specificity of 88% (95% CI, 84-91) to predict severe sleep apnea.

CONCLUSIONS

Overnight home oximetry has a high predictive performance in predicting moderate-to-severe and severe sleep apnea in patients on opioids for chronic pain. It is a useful additional tool for health care providers for the screening of sleep apnea in this high-risk group.

Understanding Buprenorphine for Use in Chronic Pain: Expert Opinion

Objective

An expert panel convened to reach a consensus on common misconceptions surrounding buprenorphine, a Schedule III partial µ-opioid receptor agonist indicated for chronic pain. The panel also provided clinical recommendations on the appropriate use of buprenorphine and conversion strategies for switching to buprenorphine from a full µ-opioid receptor agonist for chronic pain management.

Methods

The consensus panel met on March 25, 2019, to discuss relevant literature and provide recommendations on interpreting buprenorphine as a partial µ-opioid receptor agonist, prescribing buprenorphine before some Schedule II, III, or IV options, perioperative/trauma management of patients taking buprenorphine, and converting patients from a full µ-opioid receptor agonist to buprenorphine.

Results

The panel recommended that buprenorphine’s classification as a partial µ-opioid receptor agonist not be clinically translated to mean partial analgesic efficacy. The panel also recommended that buprenorphine be considered before some Schedule II, III, or IV opioids in patients with a favorable risk/benefit profile on the basis of metabolic factors, abuse potential, and tolerability and that buprenorphine be continued during the perioperative/trauma period. In addition, switching patients from a full µ-opioid receptor agonist to buprenorphine should be considered with no weaning period at starting doses that are based on the previous opioid dose.

Conclusions

These recommendations provide a framework for clinicians to address most clinical scenarios regarding buprenorphine use. The overall consensus of the panel was that buprenorphine is a unique Schedule III opioid with favorable pharmacologic properties and a safety profile that may be desirable for chronic pain management.

Respiratory depression and analgesia by opioid drugs in freely behaving larval zebrafish

An opioid epidemic is spreading in North America with millions of opioid overdoses annually. Opioid drugs, like fentanyl, target the mu opioid receptor system and induce potentially lethal respiratory depression. The challenge in opioid research is to find a safe pain therapy with analgesic properties but no respiratory depression. Current discoveries are limited by lack of amenable animal models to screen candidate drugs. Zebrafish (Danio rerio) is an emerging animal model with high reproduction and fast development, which shares remarkable similarity in their physiology and genome to mammals. However, it is unknown whether zebrafish possesses similar opioid system, respiratory and analgesic responses to opioids than mammals. In freely-behaving larval zebrafish, fentanyl depresses the rate of respiratory mandible movements and induces analgesia, effects reversed by μ-opioid receptor antagonists. Zebrafish presents evolutionary conserved mechanisms of action of opioid drugs, also found in mammals, and constitute amenable models for phenotype-based drug discovery.

When it comes to treating severe pain, a doctor’s arsenal is somewhat limited: synthetic or natural opioids such as morphine, fentanyl or oxycodone are often one of the only options available to relieve patients. Yet these compounds can make breathing slower and shallower, quickly depriving the body of oxygen and causing death. This lethal side-effect is particularly devastating as opioids misuse has reached dangerously high levels in the United States, creating an ‘opioid epidemic’ which has claimed the lives of over 80,000 Americans in 2020. It is therefore crucial to find safer drugs that do not have this effect on breathing, but this research has been slowed down by the lack of animal models in which to study the effect of new compounds.

Zebrafish are small freshwater fish that reproduce and develop fast, yet they are also remarkably genetically similar to mammals and feature a complex nervous system. However, it is not known whether the effect of opioids on zebrafish is comparable to mammals, and therefore whether these animals can be used to test new drugs for pain relief.

To investigate this question, Zaig et al. exposed zebrafish larvae to fentanyl, showing that the fish then exhibited slower lower jaw movements – a sign of decreased breathing. The fish also could also tolerate a painful stimulus for longer, suggesting that this opioid does reduce pain in the animals. Together, these results point towards zebrafish and mammals sharing similar opioid responses, demonstrating that the fish could be used to test potential pain medications. The methods Zaig et al. have developed to establish these results could be harnessed to quickly assess large numbers of drug compounds, as well as decipher how pain emerges and can be stopped.

The Effect of Perioperative Music on Medication Requirement and Hospital Length of Stay: A Meta-analysis

Objective:

To assess and quantify the effect of perioperative music on medication requirement, length of stay and costs in adult surgical patients.

Summary Background Data:

There is an increasing interest in nonpharmacological interventions to decrease opioid analgesics use, as they have significant adverse effects and opioid prescription rates have reached epidemic proportions. Previous studies have reported beneficial outcomes of perioperative music.

Methods:

A systematic literature search of 8 databases was performed from inception date to January 7, 2019. Randomized controlled trials investigating the effect of perioperative music on medication requirement, length of stay or costs in adult surgical patients were eligible. Meta-analysis was performed using random effect models, pooled standardized mean differences (SMD) were calculated with 95% confidence intervals (CI). This study was registered with PROSPERO (CRD42018093140) and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines.

Results:

The literature search yielded 2414 articles, 55 studies (N = 4968 patients) were included. Perioperative music significantly reduced postoperative opioid requirement (pooled SMD −0.31 [95% CI −0.45 to −0.16], P < 0.001, I² = 44.3, N = 1398). Perioperative music also significantly reduced intraoperative propofol (pooled SMD −0.72 [95% CI −1.01 to −0.43], P < 0.00001, I² = 61.1, N = 554) and midazolam requirement (pooled SMD −1.07 [95% CI −1.70 to −0.44], P < 0.001, I² = 73.1, N = 184), while achieving the same sedation level. No significant reduction in length of stay (pooled SMD −0.18 [95% CI −0.43 to 0.067], P = 0.15, I² = 56.0, N = 600) was observed.

Conclusions:

Perioperative music can reduce opioid and sedative medication requirement, potentially improving patient outcome and reducing medical costs as higher opioid dosage is associated with an increased risk of adverse events and chronic opioid abuse.

Intranasal Leptin Prevents Opioid-induced Sleep-disordered Breathing in Obese Mice

Respiratory depression is the main cause of morbidity and mortality associated with opioids. Obesity increases opioid-related mortality, which is mostly related to comorbid obstructive sleep apnea. Naloxone, a μ-opioid receptor blocker, is an effective antidote, but it reverses analgesia. Like humans with obesity, mice with diet-induced obesity hypoventilate during sleep and develop obstructive sleep apnea, which can be treated with intranasal leptin. We hypothesized that intranasal leptin reverses opioid-induced sleep-disordered breathing in obese mice without decreasing analgesia. To test this hypothesis, mice with diet-induced obesity were treated with morphine at 10 mg/kg subcutaneously and with leptin or placebo intranasally. Sleep and breathing were recorded by barometric plethysmography, and pain sensitivity was measured by the tail-flick test. Excitatory postsynaptic currents were recorded in vitro from hypoglossal motor neurons after the application of the μ-opioid receptor agonist [D-Ala², N-MePhe⁴, Gly-ol]-enkephalin and leptin. Morphine dramatically increased the frequency of apneas and greatly increased the severity of hypoventilation and obstructive sleep apnea. Leptin decreased the frequency of apneas, improved obstructive sleep apnea, and completely reversed hypoventilation, whereas morphine analgesia was enhanced. Our in vitro studies demonstrated that [D-Ala², N-MePhe⁴, Gly-ol]-enkephalin reduced the frequency of excitatory postsynaptic currents in hypoglossal motoneurons and that application of leptin restored excitatory synaptic neurotransmission. Our findings suggest that intranasal leptin may prevent opioid respiratory depression during sleep in patients with obesity receiving opioids without reducing analgesia.

Perioperative Care and Medication-related Hypoventilation

Cumulative evidence supports the association of adverse postoperative outcomes with obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS). Although current guidelines recommend preoperative screening for OSA and OHS, the best perioperative management pathways remain unknown. Interventions attempting to prevent complications in the postoperative period largely are consensus based and focused on enhanced monitoring, conservative measures, and specific OSA therapies, such as positive airway pressure. Until further research is available to improve the quality and strength of these recommendations, patients with known or suspected OSA and OHS should be considered at higher risk for perioperative cardiopulmonary complications.

Risk of Postoperative Hyperalgesia in Adult Patients with Preoperative Poor Sleep Quality Undergoing Open-heart Valve Surgery

Purpose

Studies have reported that preoperative poor sleep quality could decrease the pain threshold in patients undergoing noncardiac surgery. However, the risk of postoperative hyperalgesia (HA) in cardiac surgery patients with preoperative poor sleep quality remains unclear.

Patients and Methods

We retrospectively collected clinical data from patients undergoing open-heart valve surgery between May 1 and October 31, 2019, in Fuwai Hospital (Beijing). We assessed preoperative sleep quality and postoperative pain severity using the Pittsburgh sleep quality index (PSQI) and numerical pain rating scale (NPRS), respectively. A PSQI of six or greater was considered to indicate poor sleep quality, and a NPRS of four or greater was considered to indicate HA. Multivariable logistic regression analysis was used to study the risk of postoperative HA in patients with preoperative poor sleep quality.

Results

We divided 214 eligible patients into two groups based on postoperative HA; HA group: n=61 (28.5%) and nonHA group: n=153 (71.5%). Compared with nonHA patients, patients with postoperative HA showed a higher percentage of history of smoking, 17 (11.1%) vs 15 (24.6%) and alcohol abuse, 5 (3.3%) vs 6 (9.8%), higher intraoperative dose of sufentanil (median, 1.02 vs 1.12 μg/kg/h), and longer duration of ventilation with tracheal catheter (median, 760 vs 934 min). Preoperative poor sleep quality was associated independently with an increased risk of postoperative HA (adjusted odds ratio [AOR]: 2.66; 95%CI: 1.31–5.39, P=0.007). Stratification by history of smoking revealed a stronger risk of postoperative HA in nonsmoking patients with preoperative poor sleep quality (AOR: 3.40; 95%CI: 1.51–7.66, P=0.003). No risk was found in patients who had history of smoking (AOR: 0.83; 95%CI: 0.14–4.75, P=0.832).

Conclusion

Preoperative poor sleep quality is an independent risk factor for postoperative HA in adult patients undergoing open-heart valve surgery who had no history of smoking.

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.

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

Postoperative Multimodal Analgesia in Cardiac Surgery

Multimodal pain management of cardiac surgical patients is a paradigm shift in postoperative care. This promising approach features complementary medications and techniques that spare opioids and improves symptomatic and functional recovery. Although the specific elements remain to be defined, the collaboration of the health care team and patient and continuous iterative programmatic improvements are important pillars of this approach.

Anesthesia Management and Postanesthetic Recovery Following Endoscopic Sinus Surgery

OBJECTIVES

Delayed anesthesia recovery following endoscopic sinus surgery (ESS) can be an indicator of immediate complications and negatively impact healthcare efficiency. This study aims to examine clinical factors with a focus on improving clinical practice.

METHODS

Medical records of patients undergoing ESS under general anesthesia from 2014 to 2018 were reviewed. Based on the interquartile range of anesthesia recovery for the cohort, patients in the upper quartile were categorized as "prolonged" and the lowest three quartiles as "goal" recovery. Patient and surgical characteristics were investigated.

RESULTS

Analyzing 416 patients who underwent ESS, the median anesthesia recovery time was 48 [35-66] minutes. Prolonged recovery was associated with higher body mass index (odds ratio 1.50 [95% confidence interval 1.03-2.18] per 10 kg/m² , P = .03) and surgical duration (1.37 [1.10-1.72] per hour, P < .01). Inversely, goal recovery was associated with preoperative acetaminophen (0.61 [0.38-0.98], P = .04) and intraoperative remifentanil (0.55 [0.32-0.93], P = .03). Patients with prolonged recovery had higher rates of severe pain (33 (31.7%) vs. 25 (8.0%), P < .01), respiratory depression (7 [6.7] vs. 2 [0.6], P < .01), oversedation (39 [37.5] vs. 39 [12.5], P < .01), and the need for rescue opioids (52 [50] vs. 71 [22.8], P < .01). In addition to reduced postanesthesia recovery time, patients who were administered preemptive acetaminophen had lower rates of severe pain (OR 0.55 [0.31-0.98], P = .04) and nausea and vomiting (0.39 [0.17-0.87], P = .02).

CONCLUSION

Our findings substantiate the use of acetaminophen and remifentanil in ESS, facilitating anesthesia recovery. Broadly consideration of preemptive acetaminophen could further increase postoperative comfort in ESS.

LEVEL OF EVIDENCE

4 - Retrospective. Laryngoscope, 131:E815-E820, 2021.

Novel Oral Nanoparticle Formulation of Sustained Release Naloxone with Mild Withdrawal Symptoms in Mice

Chronic use of opioids can lead to tolerance, dependence, abuse, and addiction. This in turn can result in dose escalation and opioid overdose. Opioid overdose can be fatal due to severe opioid-induced respiratory depression (OIRD). Naloxone, a nonspecific antagonist of the mu-opioid receptors, is used for the reversal of OIRD. However, one of the major challenges of using naloxone is its short elimination half-life, which is significantly shorter compared to many opioid analgesics. Thus, renarcotization and rapid return to full respiratory depression might occur, specifically in individuals who have taken large doses or long-acting opioid formulations. Additionally, because of the very low oral bioavailability of naloxone, an oral formulation is not currently available. This study examines in mice a novel oral formulation of naloxone based on polymer nanoparticles (NP-naloxone). A single dose of 1 or 5 mg/kg NP-naloxone was highly effective at inhibiting the activating effects of repeated administration of 10 mg/kg morphine for at least up to 24 h. Onset of action was approximately 5 min. Reversal of morphine-induced locomotion was already detected within 1 min and a full effect of returning to baseline activity levels was observed within 5 min. Importantly, at 1 mg/kg, NP-naloxone precipitated very minimal withdrawal behaviors. At the 5 mg/kg dose, NP-naloxone precipitated approximately 40% of the jumping withdrawal behaviors of injectable naloxone. Thus, this study demonstrates that orally administered naloxone based on polymer nanoparticles has high potential to be developed to circumvent OIRD and withdrawal symptoms.

Effects of Intraoperative Ketamine on Post-Operative Recovery in Obstructive Sleep Apnea Patients: A Case-Control Study

Objective

To evaluate the post-operative outcomes of patients with obstructive sleep apnea (OSA) given intraoperative ketamine.

Design: case-control study

A total of 574 patients (287 received ketamine and 287 were matched controls) diagnosed with OSA and body mass index (BMI) > 30 who received general anesthesia were included in this study. Patients given intraoperative ketamine were matched (1:1) with those who did not receive ketamine for age, gender, BMI, ethnicity, anesthesia time, intraoperative fentanyl dose, ketamine dose, and surgery type. A sub-analysis was performed based on the dose of ketamine administered and also on the surgery type. Measured outcomes include post-operative pain scores, post-operative opioid requirements, respiratory status, oxygen use, and duration post-operatively.

Results

Intraoperative ketamine use did not decrease pain scores or post-operative opioid use when compared with the control (no intraoperative ketamine) group. Patients who received high-dose ketamine had significantly higher post-operative pain scores (p=0.048) while in the post-anesthesia care unit (PACU) and required supplemental oxygen for a longer period of time (p = 0.030), pain scores were not significant for patients who underwent orthopedic/spine procedures (p = 0.074), and high-dose ketamine group patients who underwent orthopedic/spine surgery required significantly more opioids in the PACU (p = 0.031). Among patients who received low-dose ketamine, those who underwent head, ear, nose, and throat surgery required significantly more opioids in PACU (p = 0.022).

Conclusions

Low-dose intraoperative ketamine did not decrease pain scores or post-operative opioid use significantly and did not improve standard respiratory recovery parameters for OSA patients after surgery. Neither low- nor high-dose ketamine demonstrated the anticipated benefits of low pain scores and reduced post-operative opioid use. These outcomes will differ depending on the surgery type and dose of ketamine used.

Simultaneous Determination of Parecoxib and Its Metabolite Valdecoxib Concentrations in Beagle Plasma by UPLC-MS/MS and Application for Pharmacokinetics Study

A method for the simultaneous determination of parecoxib and its metabolite valdecoxib in beagle plasma by UPLC-MS/MS was developed and validated. After the plasma was extracted by acetonitrile precipitation, the analytes were separated on an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using acetonitrile-formic acid as the mobile phase in gradient mode. The analytes were monitored by multiple reaction monitoring (MRM) in electrospray negative ion mode. The mass transfer pairs were m/z 368.97→119.01 for parecoxib, m/z 312.89→118.02 for valdecoxib, and m/z 379.98→316.02 for celecoxib (internal standard, IS). The correlation coefficients of parecoxib and valdecoxib ranged from 5 to 4000 ng/mL were greater than 0.9998. The recovery of parecoxib and valdecoxib was greater than 82.54%. The inter- and intra-day precision RSD values were 1.36~3.65% and 2.28~5.91%, respectively. The accuracy of RE values were −1.38%~1.96%. Finally, the matrix effect (ME) and stability were also within acceptable criteria. This method had been successfully applied to the pharmacokinetics of parecoxib and valdecoxib in beagle plasma after injection of parecoxib (1.33 mg/kg, intramuscular injection).

Predictive factors for sleep apnoea in patients on opioids for chronic pain

Background

The risk of death is elevated in patients taking opioids for chronic non-cancer pain. Respiratory depression is the main cause of death due to opioids and sleep apnoea is an important associated risk factor.

Methods

In chronic pain clinics, we assessed the STOP-Bang questionnaire (a screening tool for sleep apnoea; Snoring, Tiredness, Observed apnoea, high blood Pressure, Body mass index, age, neck circumference and male gender), Epworth Sleepiness Scale, thyromental distance, Mallampati classification, daytime oxyhaemoglobin saturation (SpO₂) and calculated daily morphine milligram equivalent (MME) approximations for each participant, and performed an inlaboratory polysomnogram. The primary objective was to determine the predictive factors for sleep apnoea in patients on chronic opioid therapy using multivariable logistic regression models.

Results

Of 332 consented participants, 204 underwent polysomnography, and 120 (58.8%) had sleep apnoea (AHI ≥5) (72% obstructive, 20% central and 8% indeterminate sleep apnoea), with a high prevalence of moderate (23.3%) and severe (30.8%) sleep apnoea. The STOP-Bang questionnaire and SpO₂ are predictive factors for sleep apnoea (AHI ≥15) in patients on opioids for chronic pain. For each one-unit increase in the STOP-Bang score, the odds of moderate-to-severe sleep apnoea (AHI ≥15) increased by 70%, and for each 1% SpO₂ decrease the odds increased by 33%. For each 10 mg MME increase, the odds of Central Apnoea Index ≥5 increased by 3%, and for each 1% SpO₂ decrease the odds increased by 45%.

Conclusion

In patients on opioids for chronic pain, the STOP-Bang questionnaire and daytime SpO₂ are predictive factors for sleep apnoea, and MME and daytime SpO₂ are predictive factors for Central Apnoea Index ≥5.

Trial registration number

NCT02513836

Efficacy and harms of long-term opioid therapy in chronic non-cancer pain: Systematic review and meta-analysis of open-label extension trials with a study duration ≥26 weeks

BACKGROUND AND OBJECTIVE

This updated systematic review evaluated the efficacy, acceptability and safety of long-term opioid therapy (LTOT) for chronic non-cancer pain (CNCP).

DATABASES AND DATA TREATMENT

Clinicaltrials.gov, CENTRAL and MEDLINE until June 2019. We included open-label extension trials with a study duration ≥26 weeks of RCTs with ≥2 weeks duration. Pooled estimates of event rates of categorical data and standardized mean differences (SMD) of continuous variables were calculated using a random effects model.

RESULTS

We added four new studies with 1,154 participants for a total of 15 studies with 3,590 participants. Study duration ranged between 26 and 156 weeks. Studies included patients with low back, osteoarthritis and neuropathic pain. The quality of evidence for every outcome was very low. 31.1% (95% Confidence interval [CI] 23.0%-40.7%) of patients randomized at baseline finished the open label period. 14.1% (95% CI 10.9%-19.4%) of patients dropped out to due adverse events. In 6.3% (95 CI 3.9%-10.1%) of patients serious adverse events and in 2.7% (95% CI 1.5%-4.7%) aberrant drug behaviour were noted. 0.5% (95% CI 0.2%-1.4%) of patients died.

CONCLUSIONS

Within the context of open-label extension studies, opioids maintain reduction of pain and disability and are rather well tolerated and safe. LTOT can be considered in carefully selected and monitored patients with low back, osteoarthritis and neuropathic pain who experience a clinically meaningful pain reduction with at least tolerable adverse events in short-term opioid therapy.

SIGNIFICANCE

There is very low quality evidence of the long-term efficacy, tolerability and safety of opioids for chronic low back, osteoarthritis and diabetic polyneuropathic pain within the context of open-label extension studies of randomized controlled trials. Drop out rate due to adverse events and deaths increase with study duration. One-third of patients profit from LTOT. Long-term opioid therapy can be considered in some carefully selected and monitored patients.

Prevention of Opioid Abuse and Treatment of Opioid Addiction: Current Status and Future Possibilities

Prescription opioid medications have seen a dramatic rise in misuse and abuse, leading regulators and scientists to develop policies and abuse-deterrent technologies to combat the current opioid epidemic. These abuse-deterrent formulations (ADFs) are intended to deter physical and chemical tampering of opioid-based products, while still providing safe and effective delivery for therapeutic purposes. Even though formulations with varying abuse-deterrent technologies have been approved, questions remain about their effectiveness. While these formulations provide a single means to combat the epidemic, a greater emphasis should be placed on formulations for treatment of addiction and overdose to help those struggling with opioid dependence. This article analyzes various ADFs currently in clinical use and explores potential novel systems for treatment of addiction and prevention of overdose.

Increasing Rates of Opioid Misuse Among Older Adults Visiting Emergency Departments

OBJECTIVE

This study sought to investigate factors associated with opioid misuse-related emergency department (ED) visits among older adults and changes in outcomes associated with these visits, using multiple years of nationally representative data.

METHODS

A retrospective analysis of the Nationwide Emergency Department Sample was conducted. Study inclusion was limited to adults aged 65 years and older. Diagnostic codes were used to identify opioid misuse disorder; sampling weights were used to adjust standard estimates of the errors. Descriptive and multivariate procedures were used to describe risk and visit outcomes.

RESULTS

ED visits by older adults with opioid misuse identified in the ED increased sharply from 2006 to 2014, representing a nearly 220% increase over the study period. Opioid misuse was associated with an increased number of chronic conditions, greater injury risk, and higher rates of alcohol dependence and mental health diagnoses.

CONCLUSION

The steep increase in opioid misuse observed among older adult ED visits underscores the critical need for additional research to better understand the national scope and impact of opioid misuse on older adults, as well as to better inform policy responses to meet the needs of this particular age group.