Risk factors for opioid-induced respiratory depression in surgical patients: a systematic review and meta-analyses

Preoperative assessment of patients at risk of postoperative respiratory depression

Respiratory depression during sleep is a major health challenge after surgery. The main cause is reduction in breathing due to opioids, which are commonly used for management of postoperative pain. The consequences are hypoxemia and hypercapnia, which may increase the risk of cardiovascular complications, mortality, and healthcare utilization. Identifying individuals who are at risk of postoperative respiratory depression prior to the surgery can help guide the perioperative care to reduce adverse outcomes. In this project, we developed a risk assessment model to identify individuals at risk of postoperative respiratory depression prior to the surgery, based on the demographics and changes in preoperative overnight oxyhemoglobin saturation (SpO2) levels. To achieve this, we retrospectively analyzed SpO2 signals of 159 patients, which were recorded continuously preoperatively and on the third night after surgery. Respiratory depression was defined as postoperative episodes where SpO2 was ≤85% for more than 3 minutes. From preoperative SpO2 signals, we extracted features to characterize overnight SpO2 and desaturation episodes. We streamlined a systematic process for feature selection and model development using a nested cross-validation pipeline. Our results indicated that random forest, XGBoost, and Naïve bayes demonstrated the highest predictive performance, consistently surpassing the recent available PRODIGY model. These findings suggest that demographics and preoperative SpO2 characteristics can preoperatively identify individuals at high-risk of postoperative respiratory depression, which offers a non-invasive and cost-effective method of monitoring respiratory health.

Risk of hospital inpatient opioid overdose (RHINOO): a review of factors impacting naloxone administration in patients receiving opioids

PURPOSE

Opioid medications remain a common treatment for acute pain in hospitalized patients. This study aims to identify factors contributing to opioid overdose in the inpatient population, addressing the gap in data on which patients are at higher risk for opioid-related adverse events in the hospital setting.

METHODS

A retrospective chart review of inpatients receiving at least one opioid medication was performed at a large academic medical center from January 1, 2022, through December 31, 2022. Patients who received naloxone were designated as the overdose group, while those who received opioids without naloxone served as the control group. Suspected risk factors were included in a multivariable direct logistic regression model to identify patients at higher risk for opioid-related adverse events.

RESULTS

The review included 11,050 admitted patients who received an inpatient opioid, of whom 130 received naloxone. Analysis revealed that patients with creatinine clearance (CrCl) < 60 mL/min, co-administered benzodiazepine, body mass index (BMI) > 30 kg/m2, underlying pulmonary disease, obstructive sleep apnea, chronic opioid use, and/or substance use disorder were at higher risk for requiring naloxone. These factors significantly influenced the likelihood and magnitude of in-hospital opioid overdose.

CONCLUSION

These validated risk factors should be considered when administering opioid analgesics in the inpatient setting. Consideration should be given to reducing the dose and/or frequency of opioids in addition to the use of alternative analgesic modalities for patients with these risk factors to mitigate the risk of opioid-related adverse events. Incorporating these considerations into clinical practice can enhance patient safety and outcomes.

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 use in treated and untreated obstructive sleep apnoea: remifentanil pharmacokinetics and pharmacodynamics in adult volunteers

BACKGROUND

Patients with obstructive sleep apnoea (OSA) are considered more sensitive to opioids and at increased risk of opioid-induced respiratory depression. Nonetheless, whether OSA treatment (continuous positive airway pressure, CPAP; or bilevel positive airway pressure, BIPAP) modifies this risk remains unknown. Greater opioid sensitivity can arise from altered pharmacokinetics or pharmacodynamics. This preplanned analysis of a previous cohort study of remifentanil clinical effects in OSA tested the null hypothesis that the pharmacokinetics, pharmacodynamics, or both of remifentanil, a representative μ-opioid agonist, are not altered in adults with treated or untreated OSA.

METHODS

A single-centre, prospective, open-label, cohort study administered a stepped-dose, target-controlled remifentanil infusion (target effect-site concentrations 0.5, 1, 2, 3, 4 ng ml-1) to awake adult volunteers (median age 52 yr, range 23-70) without OSA (n=20), with untreated OSA (n=33), or with treated OSA (n=21). Type III (in-home) polysomnography verified OSA. Remifentanil plasma concentrations, end-expired CO2, thermal heat tolerance, and pupil diameter (miosis) were assessed. Population pharmacokinetic (clearance, volume of distribution) and pharmacodynamic (miosis, thermal heat tolerance, end-expired CO2) models were developed.

RESULTS

Remifentanil clearance (median) was 147, 143, and 155 L h-1 (P=0.472), and volume of distribution was 19.6, 15.5, and 17.7 L (P=0.473) for subjects without OSA, untreated OSA, or treated OSA, respectively. Total body weight was an influential covariate on both remifentanil clearance and central volume of distribution. There were no statistically or clinically significant differences between the three groups in miosis EC50 or Emax, or the slopes of thermal heat tolerance or end-expired CO2vs remifentanil concentration. At a plasma remifentanil concentration of 4 ng ml-1, in participants without OSA, with untreated OSA, or with treated OSA, respectively, model-estimated pupil area (12%, 13%, and 17% of baseline, P=0.086), thermal heat tolerance (50°C, 51°C, and 51°C, P=0.218), and end-expired CO2 (6.3 kPa, 6.4 kPa, and 6.7 kPa, P=0.257) were not statistically different between groups.

CONCLUSIONS

OSA (untreated or treated) did not influence remifentanil pharmacokinetics or pharmacodynamics (miosis, analgesia, respiratory depression). Results support the null hypothesis that neither pharmacokinetics nor pharmacodynamics of remifentanil, a representative μ-opioid, are altered in adults with treated or untreated OSA. These findings provide a mechanistic explanation for the lack of influence of OSA or OSA treatment on the clinical miotic, sedative, analgesic, or respiratory depressant response to remifentanil in awake adults. The conventional notion that OSA alters sensitivity to the effects of opioids in awake adults is not supported by our findings, such that opioid dosing might not need adjustment for pharmacokinetic or pharmacodynamic considerations.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02898792, https://clinicaltrials.gov/ct2/show/NCT02898792. First Posted: September 13, 2016.

Effect of Intravenous Dexmedetomidine Premedication on Sufentanil Median Effective Concentration During Tracheal Intubation in Obese Patients: A Randomized Controlled Study

Purpose

Sufentanil is a potent opioid analgesic frequently used to suppress the tracheal intubation response. The pathophysiological changes of obesity may affect opioid pharmacokinetics and increase the risk of opioid-induced adverse effects. Dexmedetomidine as an adjunct to anesthetic induction could save the dosage of sufentanil and attenuate hemodynamic response to tracheal intubation. This study was aimed at investigating the effect of intravenous dexmedetomidine premedication on the median effective concentration (EC50) of sufentanil for tracheal intubation in obese patients.

Patients and Methods

Fifty obese patients undergoing elective bariatric or non-bariatric surgery under general anesthesia with tracheal intubation were equally randomized into the dexmedetomidine group and the saline group. Depending on the group, the patients were intravenously premedicated with 1 μg/kg dexmedetomidine or saline before anesthesia induction. Anesthesia was induced with target-controlled infusion of propofol (at 3.5 μg/mL) and sufentanil. The effect-site concentration of sufentanil for the first patient in the two groups was set at 0.4 ng/mL. The concentration of sufentanil for the next patient was determined using Dixon's up-and-down sequential method with an interval of 0.05 ng/mL, according to the responses of the previous patient. Hemodynamic variables and sufentanil dose were recorded. The EC50 and 95% confidence interval (CI) of sufentanil were determined using probit regression analysis.

Results

The EC50 of sufentanil and 95% CI were 0.25 (95% CI, 0.17-0.31) ng/mL in the dexmedetomidine group and 0.43 (95% CI, 0.34-0.46) ng/mL in the saline group (P < 0.05). The dosage of sufentanil was significantly lower in the former than in the latter. The hemodynamics were stable in both groups during the study.

Conclusion

Intravenous premedication with 1 μg/kg dexmedetomidine significantly decreased the EC50 of sufentanil and sufentanil requirement for tracheal intubation in obese patients.

Implementation of Continuous Capnography Protocol in a Postanesthesia Care Unit for Adult Patients at High-risk of Postoperative Respiratory Depression

PURPOSE

This project aimed to implement a continuous capnography protocol in the postanesthesia care unit (PACU) for postoperative adult patients who are at high risk for respiratory failure.

DESIGN

A preintervention and postintervention quality improvement design with retrospective chart reviews evaluated patient demographics (age, weight, body mass index [BMI], perioperative fluid intake and output, use of intraoperative positive-end expiratory pressure), length of surgery, average length of PACU stay, incidence of respiratory events, and adherence to a PACU capnography protocol.

METHODS

Preimplementation data were collected from retrospective chart reviews over a 3-month period. A continuous capnography protocol was implemented for same-day surgery patients with a BMI of 35 kg/m2 or greater and who received general anesthesia. Postimplementation data were collected over 3 months in addition to adherence to the capnography protocol. This was presented using descriptive statistics.

FINDINGS

Age, length of surgery, weight, BMI, perioperative fluid intake and output, and use of positive-end expiratory pressure did not impact PACU length of stay. The average PACU length of stay decreased from 76.76 to 71.82 minutes postimplementation but was not statistically significant (P = .470). The incidence of respiratory events was 6% (n = 3). After the implementation of the continuous capnography protocol, adherence to the continuous capnography monitoring was 86% (n = 43).

CONCLUSIONS

Patients who are at high risk for postoperative respiratory failure may benefit from continuous capnography monitoring in the PACU. Capnography monitoring may decrease PACU length of stay and provide earlier detection of pending respiratory depression or failure than pulse oximetry alone.

Efficacy of nonopioid analgesics and adjuvants in multimodal analgesia for reducing postoperative opioid consumption and complications in obesity: a systematic review and network meta-analysis

BACKGROUND

Managing postoperative pain in patients with obesity is challenging. Although multimodal analgesia has proved effective for pain relief, the specific impacts of different nonopioid i.v. analgesics and adjuvants on these patients are not well-defined. This study aims to assess the effectiveness of nonsteroidal antiinflammatory drugs, paracetamol, ketamine, α-2 adrenergic receptor agonists, lidocaine, magnesium, and oral gabapentinoids in reducing perioperative opioid consumption and, secondarily, in mitigating the occurrence of general and postoperative pulmonary complications (POPCs), nausea, vomiting, PACU length of stay (LOS), and hospital LOS among surgical patients with obesity.

METHODS

A systematic review and network meta-analysis was performed. PubMed, Scopus, Web of Science, CINAHL, and EMBASE were searched. Only English-language RCTs investigating the use of nonopioid analgesics and adjuvants in adult surgical patients with obesity were included. The quality of evidence and certainty were assessed using the RoB 2 tool and GRADE framework, respectively.

RESULTS

In total, 37 RCTs involving 3602 patients were included in the quantitative analysis. Compared with placebo/no intervention or a comparator, dexmedetomidine, ketamine, lidocaine, magnesium, and gabapentin significantly reduced postoperative opioid consumption after surgery. Ketamine/esketamine also significantly reduced POPCs. Ibuprofen, dexmedetomidine, and lidocaine significantly reduced postoperative nausea, whereas dexmedetomidine, either alone or combined with pregabalin, and lidocaine reduced postoperative vomiting. Dexmedetomidine significantly reduced PACU LOS, whereas both paracetamol and lidocaine reduced hospital LOS.

CONCLUSIONS

Intravenous nonopioid analgesics and adjuvants are crucial in multimodal anaesthesia, reducing opioid consumption and enhancing postoperative care in adult surgical patients with obesity.

SYSTEMATIC REVIEW PROTOCOL

CRD42023399373 (PROSPERO).

Safety of Co-Crystal of Tramadol-Celecoxib (CTC) in Patients with Acute Moderate-to-Severe Pain: Pooled Analysis of Three Phase 3 Randomized Trials

INTRODUCTION

Multi-modal analgesia is desirable for the management of acute pain since it can provide effective pain relief at lower doses, thereby aiding tolerability. Co-crystal of tramadol-celecoxib (CTC) provides effective analgesia in models of acute pain. Co-crystallization can alter the pharmacokinetics of individual components, potentially improving tolerability. We sought to better understand the safety and tolerability of CTC in patients with acute postoperative pain.

METHODS

We conducted a pooled analysis of safety data from three phase 3 randomized controlled trials in adults with acute moderate-to-severe pain following oral surgery, bunionectomy, and elective abdominal hysterectomy. We present data for CTC 200 mg twice daily (BID) and its comparators: tramadol 50 mg four times daily (QID) (one trial), tramadol 100 mg QID (two trials), celecoxib 100 mg BID (two trials), and placebo (three trials).

RESULTS

In total, n = 551 patients received CTC 200 mg BID, n = 183 received tramadol 50 mg QID, n = 368 received tramadol 100 mg QID, n = 388 received celecoxib 100 mg BID, and n = 274 received placebo. The prevalence of adverse events (AEs) related to study drug up to 48 h was numerically lower with CTC 200 mg BID (35.9%) than with tramadol 50 mg QID (47.5%) and 100 mg QID (44.8%) but greater than with celecoxib 100 mg BID (12.4%) and placebo (20.4%). The most frequent AEs related to study drug up to 48 h were somnolence, nausea, dizziness, and vomiting, which occurred more frequently in patients receiving tramadol 100 mg QID than in those receiving CTC 200 mg BID.

CONCLUSION

CTC 200 mg BID appears to be better tolerated than tramadol 100 mg QID, possibly because of reduced total exposure to tramadol. This may contribute to a more favorable benefit-risk profile for CTC versus individual components, making it a promising treatment for acute pain.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT03108482, NCT02982161 (EudraCT: 2016-000592-24), NCT03062644 (EudraCT: 2016-000593-38).

The knowledge profile, attitudes, and perioperative management of Chinese anesthesiologists towards patients with obstructive sleep apnea: a cross-sectional survey

BACKGROUNDS

Obstructive sleep apnea syndrome (OSA) is increasingly encountered by anesthesiologists in clinical practice. However, research on managing these patients among anesthesiologists in China is scarce. This study aims to investigate the knowledge, attitudes, and perioperative management strategies for OSA patients among Chinese anesthesiologists.

METHODS

In this cross-sectional study, anesthesiologists from various hospitals across China were invited to complete a thirty-eight-item online questionnaire survey between October 1 and November 1, 2022. The Obstructive Sleep Apnea Knowledge and Attitude (OSAKA) scale was utilized to measure their knowledge and attitudes.

RESULTS

A total of 470 valid participants were recruited for this research, resulting in a valid response rate of 73.3%. (1) While the majority of participants acknowledged the importance of identifying OSA during perioperative management, only 58.3% felt confident in managing OSA patients; (2) Anesthesiologists with higher professional titles and longer work experience exhibited greater confidence in managing OSA patients; (3) Just under half of the participants were familiar with the STOP-Bang and Berlin questionnaires. Anesthesiologists with over 20 years of work experience were more likely to use the STOP-Bang and Berlin questionnaires compared to those with less than 10 years of work experience (OR = 3.166, P < 0.001); (4) 71.1% of participants expressed approval regarding the preparation of sugammadex for muscle relaxation reversal, while only 32.8% approved the safety of opioid use for postoperative analgesia in OSA patients.

CONCLUSION

The study displayed that Chinese anesthesiologists have inadequate knowledge and perioperative management of OSA than expected. However, they have positive attitudes towards the assessment and management of OSA. The study highlights the need for high-quality training to identify and manage OSA among Chinese anesthesiologists.

Quality improvement initiative: use of the STOP-BANG score and monitoring to reduce adverse events in hospitalised patients at risk of obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea increases risk of respiratory depression with administration of sedatives, narcotics or anxiolytics. To reduce adverse events during hospital admission, we implemented STOP-BANG screening to prompt respiratory monitoring for inpatients receiving these medications. This study reports on protocol development, implementation and an initial analysis over 5 years to evaluate implementation success and outcomes.

INTERVENTION

The STOP-BANG measure was embedded in the nurse navigator at admission. If the score was ≥3 and sedatives, narcotics and/or anxiolytics were ordered, the provider was prompted to monitor patients with continuous pulse oximetry and/or capnography.

METHODS

We assessed the impact of the intervention using a retrospective pre-post design. Preprotocol data from all adult inpatients over a 2.5-year period, and postprotocol data from all adult inpatients from over a 5-year period, were extracted from the electronic health record. Outcomes included use of monitoring; adverse events during hospitalisation were included to evaluate the effects of the intervention: mortality, rate of rapid response team events, reversal and/or rescue, intensive care unit admission and orders for positive airway pressure equipment.

RESULTS

The combined preprotocol and postprotocol sample included 254 121 patients. After protocol implementation, overall mortality for patients receiving sedatives, narcotics or anxiolytics decreased slightly from 2.1% to 1.9% (p<0.001). In the postprotocol cohort only (n=193 744), monitored patients had a higher probability of experiencing all adverse events. Among monitored patients, mortality was lowest in the high-risk group (STOP-BANG≥5).

DISCUSSION

Triaging by STOP-BANG coupled with monitoring appeared to be helpful for patients at highest risk of obstructive sleep apnoea. Given the complexity of obstructive sleep apnoea, further pursuit of subphenotypes is warranted.

Efficacy of an mHealth intervention to support pain self-management and improve analgesia in patients with rib fractures: protocol for a randomised controlled trial

INTRODUCTION

In light of the risks of over-reliance on opioid analgesia during recovery from rib fractures, there is increased interest in the efficacy of non-pharmacological approaches to pain management. This paper describes the protocol for a double-blind randomised controlled trial to evaluate the efficacy of an mHealth intervention for reducing pain intensity, pain-related distress and opioid use during early recovery from rib fractures.

METHODS AND ANALYSIS

Adults (N=120) with isolated rib fractures will be recruited within 24 hours of admission to a large public hospital in Sydney, Australia (single site), and randomised (1:1 allocation) to an intervention or active control group. Clinicians, participants and statisticians will be blind to participants' group allocation. The intervention (PainSupport) consists of a brief pain self-management educational video, followed by twice daily supportive Short Message Service (SMS) text messages for 14 days. Participants in the active control group receive the same video but not the supportive text messages. Participants in both groups continue to receive usual care throughout the trial. The primary outcome will be self-reported pain intensity on respiration measured using a Numerical Rating Scale. Secondary outcomes will include opioid use, pain-related distress, adherence to behavioural pain management strategies and the acceptability and feasibility of the intervention. Participants will complete questionnaires at baseline and then on days 1-7 and day 14 of the trial. A feedback survey will be completed at the end of the trial (day 15). Linear mixed models will be used to evaluate the main effect of the group on the primary and secondary outcomes and to explore differences between outcome trends recorded over the trial. Analyses will be based on the intention-to-treat principle to minimise bias secondary to missing data or dropouts.

ETHICS AND DISSEMINATION

The study protocol has been reviewed and approved by the Northern Sydney Local Health District Human Research Ethics Committee (Australia). Informed consent is a requirement for participation in the study. Study results will be published in peer-reviewed journals and presented at scientific and professional meetings.

TRIAL REGISTRATION NUMBER

ACTRN12623000006640.

Effect of multimodal opioid-sparing anesthesia on intestinal function and prognosis of elderly patients with hypertension after colorectal cancer surgery

PURPOSE

Colorectal cancer (CRC) surgery in elderly patients with hypertension poses challenges due to potential complications and prolonged recovery. This study aimed to assess the impact of multimodal opioid-sparing anesthesia on intestinal function and prognosis of elderly hypertension patients undergoing CRC surgery.

METHODS

A total of 80 elderly hypertension patients who underwent open surgery for CRC in the People's Hospital of Xinjiang Uygur Autonomous Region from October 2020 to October 2022 were selected and randomly divided into two group (A and B, n = 40) through the random number table method. Group A received multimodal opioid-sparing anesthesia, defined as low-dose opioid general anesthesia combined with a transversus abdominis plane block, incision infiltration with local anesthetics, and postoperative analgesia via a patient-controlled analgesia (PCA) pump, with the remifentanil dose set at one-third (± 10%) of the conventional group's dose. Group B received conventional opioid anesthesia, involving standard general anesthesia maintained with remifentanil at 0.4-0.5 µg/(kg·min), incision infiltration with local anesthetics, and postoperative PCA. Primary outcomes included mean arterial pressure (MAP) and heart rate (HR), changes in albumin, C-reactive protein (CRP) and white blood cell (WBC), indicators of intestinal function recovery (the recovery time of bowel sounds, the first exhaust time, the first defecation time and the feeding recovery time), and visual analogue scale (VAS) pain scores. Second outcomes included postoperative complications and total hospital stays.

RESULTS

After excluding 8 patients, 72 were included in the final analysis. Compared with patients in the B group, patients in the A group exhibited shorter recovery time of bowel sounds, first exhaust time and feeding recovery time (P < 0.05), higher levels of postoperative albumin, and lower levels of CRP and WBC (P < 0.05). Moreover, the incidence of nausea and vomiting was lower and the total hospital stays were fewer in the A group than in the B group (P < 0.05).

CONCLUSION

Multimodal opioid-sparing anesthesia contributes to rapid recovery of postoperative intestinal function and reduction of postoperative adverse reactions. Therefore, it is safe and feasible to apply multimodal opioid-sparing anesthesia to elderly hypertension patients receiving open surgery for CRC.

Extubation-Related Complications

Extubation represents an essential component of airway management. While being a common procedure in anesthesiology and critical care medicine, it is accompanied by a significant risk of morbidity and mortality. Safe extubation requires considerable skills, risk stratification and advanced planning. It is important to emphasize that intentional extubation is always an elective procedure, and as such should only be executed when conditions are optimal. The purpose of this review is to discuss the complications associated with planned extubation in the adult patient, including risk factors and management strategies, mainly focusing on the postoperative setting.

A machine learning algorithm for detecting abnormal patterns in continuous capnography and pulse oximetry monitoring

Continuous capnography monitors patient ventilation but can be susceptible to artifact, resulting in alarm fatigue. Development of smart algorithms may facilitate accurate detection of abnormal ventilation, allowing intervention before patient deterioration. The objective of this analysis was to use machine learning (ML) to classify combined waveforms of continuous capnography and pulse oximetry as normal or abnormal. We used data collected during the observational, prospective PRODIGY trial, in which patients receiving parenteral opioids underwent continuous capnography and pulse oximetry monitoring while on the general care floor [1]. Abnormal ventilation segments in the data stream were reviewed by nine experts and inter-rater agreement was assessed. Abnormal segments were defined as the time series 60s before and 30s after an abnormal pattern was detected. Normal segments (90s continuous monitoring) were randomly sampled and filtered to discard sequences with missing values. Five ML models were trained on extracted features and optimized towards an Fβ score with β = 2. The results show a high inter-rater agreement (> 87%), allowing 7,858 sequences (2,944 abnormal) to be used for model development. Data were divided into 80% training and 20% test sequences. The XGBoost model had the highest Fβ score of 0.94 (with β = 2), showcasing an impressive recall of 0.98 against a precision of 0.83. This study presents a promising advancement in respiratory monitoring, focusing on reducing false alarms and enhancing accuracy of alarm systems. Our algorithm reliably distinguishes normal from abnormal waveforms. More research is needed to define patterns to distinguish abnormal ventilation from artifacts.

Continuous Intra-Incisional Bupivacaine for Postoperative Analgesia after Hip Nailing Surgery: A Randomized Clinical Trial

Background

The effectiveness of continuous wound infiltration (CWI) as a postoperative pain-control technique has been shown in many surgical procedures. This study investigates the effect of CWI of local anesthetic on postoperative pain control in intertrochanteric fracture patients undergoing hip nailing surgery.

Methods

In this randomized clinical trial, 48 patients who were scheduled for hip nailing surgery were randomly assigned to receive (n = 24) or not receive (n = 24) bupivacaine infusion through a catheter inside the surgical wound, postoperatively. Pain intensity (NRS), required dose of morphine, and drug-related complications within 24 hours of the intervention were assessed and compared.

Results

Pain intensity was significantly lower in the bupivacaine group both during the recovery room stay and in the ward in the first 24 hours after the procedure (P < 0.001). In the recovery room, the control group patients had a higher morphine consumption compared to the bupivacaine group (P < 0.001) and requested it earlier than the bupivacaine group (60 (45-60) vs. 360 (195-480) minutes) (P < 0.001). In the ward, all control group patients used the PCA morphine pump, while only 54% of the bupivacaine group self-administered morphine through the pump, with a significantly lower total morphine consumption (1 (0-2) vs. 10 (5-14) mg, P < 0.001). None of the patients in the bupivacaine group required additional morphine, while 37.5% of the control requested additional morphine (P=0.002). Altogether, the control group had a higher total morphine consumption compared to the bupivacaine group in the first 24 hours (10.5 (6-15.5) vs. 1 (0-2) mg, P < 0.001).

Conclusion

CWI of bupivacaine helps better pain reduction during the early postoperative hours while it reduces opioid consumption, minimizes nausea and vomiting, and improves patient satisfaction.

Measures of overnight oxygen saturation to characterize sleep apnea severity and predict postoperative respiratory depression

BACKGROUND

Sleep apnea syndrome, characterized by recurrent cessation (apnea) or reduction (hypopnea) of breathing during sleep, is a major risk factor for postoperative respiratory depression. Challenges in sleep apnea assessment have led to the proposal of alternative metrics derived from oxyhemoglobin saturation (SpO2), such as oxygen desaturation index (ODI) and percentage of cumulative sleep time spent with SpO2 below 90% (CT90), as predictors of postoperative respiratory depression. However, their performance has been limited with area under the curve of 0.60 for ODI and 0.59 for CT90. Our objective was to propose novel features from preoperative overnight SpO2 which are correlated with sleep apnea severity and predictive of postoperative respiratory depression.

METHODS

Preoperative SpO2 signals from 235 surgical patients were retrospectively analyzed to derive seven features to characterize the sleep apnea severity. The features included entropy and standard deviation of SpO2 signal; below average burden characterizing the area under the average SpO2; average, standard deviation, and entropy of desaturation burdens; and overall nocturnal desaturation burden. The association between the extracted features and sleep apnea severity was assessed using Pearson correlation analysis. Logistic regression was employed to evaluate the predictive performance of the features in identifying postoperative respiratory depression.

RESULTS

Our findings indicated a similar performance of the proposed features to the conventional apnea-hypopnea index (AHI) for assessing sleep apnea severity, with average area under the curve ranging from 0.77 to 0.81. Notably, entropy and standard deviation of overnight SpO2 signal and below average burden showed comparable predictive capability to AHI but with minimal computational requirements and individuals' burden, making them promising for screening purposes. Our sex-based analysis revealed that compared to entropy and standard deviation, below average burden exhibited higher sensitivity in detecting respiratory depression in women than men.

CONCLUSION

This study underscores the potential of preoperative SpO2 features as alternative metrics to AHI in predicting postoperative respiratory.

Continuous Capnography for Early Detection of Respiratory Compromise During Gastroenterological Procedural Sedation and Analgesia

Gastroenterology nurses working across a variety of clinical settings are responsible for periprocedural monitoring during moderate to deep procedural sedation and analgesia (PSA) to identify signs of respiratory compromise and intervene to prevent cardiorespiratory events. Pulse oximetry is the standard of care for respiratory monitoring, but it may delay or fail to detect abnormal ventilation during PSA. Continuous capnography, which measures end-tidal CO2 as a marker of alveolar ventilation, has been endorsed by a number of clinical guidelines. Large clinical trials have demonstrated that the addition of continuous capnography to pulse oximetry during PSA for various gastroenterological procedures reduces the incidence of hypoxemia, severe hypoxemia, and apnea. Studies have shown that the cost of adding continuous capnography is offset by the reduction in adverse events and hospital length of stay. In the postanesthesia care unit, continuous capnography is being evaluated for monitoring opioid-induced respiratory depression and to guide artificial airway removal. Studies are also examining the utility of continuous capnography to predict the risk of opioid-induced respiratory depression among patients receiving opioids for primary analgesia. Continuous capnography monitoring has become an essential tool to detect early signs of respiratory compromise in patients receiving PSA during gastroenterological procedures. When combined with pulse oximetry, it can help reduce cardiorespiratory adverse events, improve patient outcomes and safety, and reduce health care costs.

Effect of an opioid-free anesthetic on postoperative opioid consumption after laparoscopic bariatric surgery: a prospective, single-blinded, randomized controlled trial

INTRODUCTION

Opioid administration has the benefit of providing perioperative analgesia but is also associated with adverse effects. Opioid-free anesthesia (OFA) may reduce postoperative opioid consumption and adverse effects after laparoscopic bariatric surgery. In this randomized controlled study, we hypothesized that an opioid-free anesthetic using lidocaine, ketamine, and dexmedetomidine would result in a clinically significant reduction in 24-hour postoperative opioid consumption when compared with an opioid-inclusive technique.

METHODS

Subjects presenting for laparoscopic or robotic bariatric surgery were randomized in a 1:1 ratio to receive either standard opioid-inclusive anesthesia (group A: control) or OFA (group B: OFA). The primary outcome was opioid consumption in the first 24 hours postoperatively in oral morphine equivalents (OMEs). Secondary outcomes included postoperative pain scores, patient-reported incidence of opioid-related adverse effects, hospital length of stay, patient satisfaction, and ongoing opioid use at 1 and 3 months after hospital discharge.

RESULTS

181 subjects, 86 from the control group and 95 from the OFA group, completed the study per protocol. Analysis of the primary outcome showed no significant difference in total opioid consumption at 24 hours between the two treatment groups (control: 52 OMEs vs OFA: 55 OMEs, p=0.49). No secondary outcomes showed statistically significant differences between groups.

CONCLUSIONS

This study demonstrates that an OFA protocol using dexmedetomidine, ketamine, and lidocaine for laparoscopic or robotic bariatric surgery was not associated with a reduction in 24-hour postoperative opioid consumption when compared with an opioid-inclusive technique using fentanyl.

The Development and Implementation of the Fast-Pace Assessment Framework and Tiered Analgesic Orders for Opioid Optimization

BACKGROUND

Within the context of the opioid epidemic, changes needed to be made in the prescription and administration of analgesics. The purpose of this paper is to describe the development and implementation of a project that utilized a holistic pain assessment framework and introduced new order sets to guide the integration of nonopioid, opioid, and co-analgesics in a quaternary care medical center.

METHODS

An interdisciplinary team updated policies and procedures for pain assessment and opioid administration and created new analgesic order sets for both adult and pediatric patients. Following requisite approvals, these order sets were integrated into the electronic health record. Education of clinicians, patients, and caregivers was provided to facilitate implementation of these new clinical practices.

RESULTS

Prescribers' levels of adherence with the use of the pain order sets ranged from 80% to 90% and no adverse effects were reported. Education of nursing staff was incorporated into hospital orientation. Ongoing evaluations are providing insights into how the new policies and procedures can be optimized to ensure reliable, safe, and effective pain management.

CONCLUSIONS

Since the implementation of the opioid optimization project, adherence with the tiered, multimodal approach to analgesic prescribing is high. Next steps include both qualitative and quantitative evaluations of the benefits and challenges associated with this practice change. For example, systems will be developed to monitor nurses' adherence with the implementation of the pain order sets and the use of both pharmacologic and nonpharmacologic pain management interventions.

Opioid-Free Anesthesia in Bariatric Surgery: Is It the One and Only? A Comprehensive Review of the Current Literature

Opioid-free anesthesia (OFA) is a heterogeneous group of general anesthesia techniques in which the intraoperative use of opioids is eliminated. This strategy aims to decrease the risk of complications and improve the patient's safety and comfort. Such potential advantages are particularly beneficial for selected groups of patients, among them obese patients undergoing laparoscopic bariatric surgery. Opioids have been traditionally used as an element of balanced anesthesia, and replacing them requires using a combination of coanalgesics and various types of local and regional anesthesia, which also have their side effects, limitations, and potential disadvantages. Moreover, despite the growing amount of evidence, the empirical data on the superiority of OFA compared to standard anesthesia with multimodal analgesia are contradictory, and potential benefits in many studies are being questioned. Additionally, little is known about the long-term sequelae of such a strategy. Considering the above-mentioned issues, this study aims to present the potential benefits, risks, and difficulties of implementing OFA in bariatric surgery, considering the current state of knowledge and literature.

Pro-Con Debate: Universal Versus Selective Continuous Monitoring of Postoperative Patients

In this Pro-Con commentary article, we discuss use of continuous physiologic monitoring for clinical deterioration, specifically respiratory depression in the postoperative population. The Pro position advocates for 24/7 continuous surveillance monitoring of all patients starting in the postanesthesia care unit until discharge from the hospital. The strongest arguments for universal monitoring relate to inadequate assessment and algorithms for patient risk. We argue that the need for hospitalization in and of itself is a sufficient predictor of an individual's risk for unexpected respiratory deterioration. In addition, general care units carry the added risk that even the most severe respiratory events will not be recognized in a timely fashion, largely due to higher patient to nurse staffing ratios and limited intermittent vital signs assessments (e.g., every 4 hours). Continuous monitoring configured properly using a "surveillance model" can adequately detect patients' respiratory deterioration while minimizing alarm fatigue and the costs of the surveillance systems. The Con position advocates for a mixed approach of time-limited continuous pulse oximetry monitoring for all patients receiving opioids, with additional remote pulse oximetry monitoring for patients identified as having a high risk of respiratory depression. Alarm fatigue, clinical resource limitations, and cost are the strongest arguments for selective monitoring, which is a more targeted approach. The proponents of the con position acknowledge that postoperative respiratory monitoring is certainly indicated for all patients, but not all patients need the same level of monitoring. The analysis and discussion of each point of view describes who, when, where, and how continuous monitoring should be implemented. Consideration of various system-level factors are addressed, including clinical resource availability, alarm design, system costs, patient and staff acceptance, risk-assessment algorithms, and respiratory event detection. Literature is reviewed, findings are described, and recommendations for design of monitoring systems and implementation of monitoring are described for the pro and con positions.

Intraoperative Music to Promote Patient Outcome (IMPROMPTU): A Double-Blind Randomized Controlled Trial

INTRODUCTION

Perioperative music can have beneficial effects on postoperative pain, anxiety, opioid requirement, and the physiological stress response to surgery. The aim was to assess the effects of intraoperative music during general anesthesia in patients undergoing surgery for esophagogastric cancer.

MATERIALS AND METHODS

The IMPROMPTU study was a double-blind, placebo-controlled, randomized multicenter trial. Adult patients undergoing surgery for stage II-III esophagogastric cancer were eligible. Exclusion criteria were a hearing impairment, insufficient Dutch language knowledge, corticosteroids use, or objection to hearing unknown music. Patients wore active noise-cancelling headphones intraoperatively with preselected instrumental classical music (intervention) or no music (control). Computerized randomization with centralized allocation, stratified according to surgical procedure using variable block sizes, was employed. Primary endpoint was postoperative pain on the first postoperative day. Secondary endpoints were postoperative pain during the first postoperative week, postoperative opioid requirement, intraoperative medication requirement, the stress response to surgery, postoperative complication rate, length of stay, and mortality, with follow-up lasting 30 d.

RESULTS

From November 2018 to September 2020, 145 patients were assessed and 83 randomized. Seventy patients (music n = 31, control n = 39) were analyzed. Median age was 70 [IQR 63-70], and 48 patients (69%) were male. Music did not reduce postoperative pain (numeric rating scale 1.8 (SD0.94) versus 2.0 (1.0), mean difference -0.28 [95% CI -0.76-0.19], P = 0.236). No statistically significant differences were seen in medication requirement, stress response, complication rate, or length of stay.

CONCLUSIONS

Intraoperative, preselected, classical music during esophagogastric cancer surgery did not significantly improve postoperative outcome and recovery when compared to no music using noise-cancelling headphones.

Successful Anesthetic Management for Obese Patients with Interstitial Lung Disease Undergoing Laparoscopic Sleeve Gastrectomy: A Bridge to Improved Lung Transplant Eligibility

BACKGROUND Patients with obesity with interstitial lung diseases (ILD) are encouraged to lose weight, as it improves lung function and lung transplant eligibility. As exercise tolerance in these patients is low and weight gain is a common adverse effect of corticosteroids, bariatric surgery can be an effective method for the management of obesity in this patient group. However, perioperative complications in such high-risk patients remain a concern. Therefore, we aimed to demonstrate successful anesthetic management for obese patients with ILD, which may be practically utilized to reduce perioperative pulmonary complications and improve outcomes. CASE REPORT Our case report presents a 42-year-old man with ILD who underwent laparoscopic sleeve gastrectomy (LSG). Preoperative studies revealed severe restrictive disease, right ventricular overload with assessed intermediate risk of pulmonary hypertension, and heart failure, with preserved left ventricle fraction but with poor exercise tolerance. Patient had opioid-free anesthesia (OFA) and postoperative multimodal analgesia. Following a 24-h stay in the Post-Anesthesia Care Unit, the patient was transferred to the ward and ultimately discharged home 2 days thereafter. At the 1-year follow-up, the patient reduced his weight by 40 kg and reported a significant improvement in physical capacity. CONCLUSIONS Our record demonstrates that OFA can be successfully used in high-risk patients with ILD undergoing LSG. In a period of a year, the patient improved so much that he no longer required lung transplantation, which may encourage clinicians to provide bariatric surgery using the OFA technique in the population of patients with obesity and severe respiratory illness.

Trends in pain undertreatment among lung cancer patients at the EOL: Analysis of urban city medical insurance data in China

BACKGROUND

Cancer-related pain is one of the common priority symptoms in advanced lung cancer patients at the end-of-life (EOL). Alleviating pain is undoubtedly a critical component of palliative care in lung cancer. Our study was initiated to examined trends in opioid prescription-level outcomes as potential indicators of undertreated pain in China.

METHODS

This study used data on 1330 patients diagnosed with lung cancer of urban city medical insurance in China who died between 2014 and 2017. Opioid prescription-level outcomes were determined by annual trends of the proportion of patients filling an opioid prescription, the total dose of opioids filled by decedents, and morphine milligram equivalents per day (MMED) at the EOL (defined as the 60 days before death). We further analyzed monthly changes in the number of opioid prescriptions filled, MMED, and mean daily dose of opioids per prescription (MDDP) of the last 60 days of life by year at death and age, respectively.

RESULTS

A total of 959 patients with exact dates of death were included, with 432 cases (45.06%; 95% CI: 44.36%-45.77%) receiving at least one opioid prescription at the EOL. The declining trends were shown in the proportion of patients filling any opioid prescription, the total dose of opioids filled by decedents and MMED, with an annual decrease of 0.341% (p = 0.01), 104.23 mg (p = 0.011) and 2.84 mg (p = 0.014), respectively. Within the 31-60 days to the 0-30 days of life, the MMED declined 6.08 mg (95% CI: -7.14 to -5.03; p = 0.000351), while the number of opioid prescriptions rose 0.66 (95% CI: 0.160-1.16; p = 0.025). Like the MMED, the MDDP fell 4.11 mg (95% CI: -5.86 to -2.37; p = 0.005) within the last month before death compared to the previous month.

CONCLUSION

Terminal lung cancer populations in urban China have experienced reduced access to opioids at the EOL. The clinicians did not prescribe a satisfactory dose of opioids per prescription, while the patients suffered increasing pain in the last 30 days of life. Sufficient opioid analgesic administration should be advocated for lung cancer patients during the EOL period.

Trends, outcomes, and factors associated with in-hospital opioid overdose following major surgery

Background

With the growing opioid epidemic across the US, in-hospital utilization of opioids has garnered increasing attention. Using a national cohort, this study sought to characterize trends, outcomes, and factors associated with in-hospital opioid overdose (OD) following major elective operations.

Methods

We identified all adult (≥18 years) hospitalizations entailing select elective procedures in the 2016-2020 National Inpatient Sample. Patients who experienced in-hospital opioid overdose were characterized as OD (others: Non-OD). The primary outcome of interest was in-hospital OD. Multivariable logistic and linear regression models were developed to evaluate the association between in-hospital OD and mortality, length of stay (LOS), hospitalization costs, and non-home discharge.

Results

Of an estimated 11,096,064 hospitalizations meeting study criteria, 5375 (0.05 %) experienced a perioperative OD. Compared to others, OD were older (66 [57-73] vs 64 [54-72] years, p < 0.001), more commonly female (66.3 vs 56.7 %, p < 0.001), and in the lowest income quartile (26.4 vs 23.2 %, p < 0.001). After adjustment, female sex (Adjusted Odds Ratio [AOR] 1.68, 95 % Confidence Interval [CI] 1.47-1.91, p < 0.001), White race (AOR 1.19, CI 1.01-1.42, p = 0.04), and history of substance use disorder (AOR 2.51, CI 1.87-3.37, p < 0.001) were associated with greater likelihood of OD. Finally, OD was associated with increased LOS (β +1.91 days, CI [1.60-2.21], p < 0.001), hospitalization costs (β +$7500, CI [5900-9100], p < 0.001), and greater odds of non-home discharge (AOR 2.00, CI 1.61-2.48, p < 0.001).

Conclusion

Perioperative OD remains a rare but costly complication after elective surgery. While pain control remains a priority postoperatively, protocols and recovery pathways must be re-examined to ensure patient safety.

Considerations for Functional Nasal Surgery in the Obstructive Sleep Apnea Population

Obstructive sleep apnea (OSA) and nasal obstruction are common in the general population and frequently treated by otolaryngologists and facial plastic surgeons. Understanding the appropriate pre-, peri-, and postoperative management of OSA patients undergoing functional nasal surgery is important. OSA patients should be appropriately counseled in the preoperative period on their increased anesthetic risk. In OSA patients who are continuous positive airway pressure (CPAP) intolerant, the role of drug-induced sleep endoscopy should be discussed with the patient, and depending on the surgeon's practice may prompt referral to a sleep specialist. Should multilevel airway surgery be indicated, it can safely be performed in most OSA patients. Surgeons should communicate with the anesthesiologist regarding an airway plan given this patient population's higher propensity for having a difficult airway. Given their increased risk of postoperative respiratory depression, extended recovery time should be given to these patients and the use of opioids as well as sedatives should be minimized. During surgery, one can consider using local nerve blocks to reduce postoperative pain and analgesic use. After surgery, clinicians can consider opioid alternatives such as nonsteroidal anti-inflammatory agents. Neuropathic agents, such as gabapentin, require further research in their indications for managing postoperative pain. CPAP is typically held for a period of time after functional rhinoplasty. The decision on when to restart CPAP should be individualized to the patient based on their comorbidities, OSA severity, and surgical maneuvers performed. More research would provide further guidance in this patient population to shape more specific recommendations regarding their perioperative and intraoperative course.

Anesthetic challenges of pregnant obesity women

Obesity causes significant morbidity and increases the mortality risk for both mother and fetus. With an increasing projected prevalence, it is vital that the obstetric anesthetist is equipped with the knowledge and tools to manage these women. A multi-disciplinary team approach and early planning is required. Neuraxial analgesia for labor helps to negate the need for general anesthesia, which is associated with increased risk in this subset of women. Catheter techniques for neuraxial anesthesia allow for titration, manipulation, and prolongation of the anesthetic block to reduce the risk of conversion to general anesthesia.

Identifying Early Opioid-Induced Respiratory Depression and Rapid Response Team Activation

BACKGROUND

Opioids can cause respiratory depression, which could lead to patient harm. The project site noted a gap in identifying and monitoring postsurgical thoracic patients at risk for opioid-induced respiratory depression (OIRD), so an evidence-based solution was sought.

AIMS

The purpose of this quality improvement project was to determine if translating the research by Khanna et al. (2020) on implementing the prediction of opioid-induced respiratory depression in patients monitored by capnography (PRODIGY) risk prediction tool would affect rapid response team (RRT) activation among postsurgical thoracic patients in a cardiovascular and thoracic care unit (CVTCU) at John Muir Medical Center, Concord Campus over four weeks.

METHODS

The four-week quantitative quasi-experimental project had a total sample size of 29 participants. Pulse oximetry was used to identify OIRD in the comparison group (n = 12). The implementation group consisted of patients identified as at-risk for OIRD by the PRODIGY risk prediction tool and were monitored with pulse oximetry and capnography (n = 17).

RESULTS

A χ2 analysis showed χ2 (1, n = 29) = .73, p = .393 for activation of the RRT using the PRODIGY risk prediction tool, which was not statistically significant. However, clinical significance was supported by a 5.9% increase in RRT activations.

CONCLUSION

Based on the results, implementing the PRODIGY risk prediction tool and capnography monitoring on at-risk patients may affect RRT activation in this population.

Preoperative risk evaluation and perioperative management of patients with obstructive sleep apnea: a narrative review

Obstructive sleep apnea (OSA) is a common sleep-breathing disorder associated with significant comorbidities and perioperative complications. This narrative review is aimed at comprehensively overviewing preoperative risk evaluation and perioperative management strategies for patients with OSA. OSA is characterized by recurrent episodes of upper airway obstruction during sleep leading to hypoxemia and arousal. Anatomical features, such as upper airway narrowing and obesity, contribute to the development of OSA. OSA can be diagnosed based on polysomnography findings, and positive airway pressure therapy is the mainstay of treatment. However, alternative therapies, such as oral appliances or upper airway surgery, can be considered for patients with intolerance. Patients with OSA face perioperative challenges due to difficult airway management, comorbidities, and effects of sedatives and analgesics. Anatomical changes, reduced upper airway muscle tone, and obesity increase the risks of airway obstruction, and difficulties in intubation and mask ventilation. OSA-related comorbidities, such as cardiovascular and respiratory disorders, further increase perioperative risks. Sedatives and opioids can exacerbate respiratory depression and compromise airway patency. Therefore, careful consideration of alternative pain management options is necessary. Although the association between OSA and postoperative mortality remains controversial, concerns exist regarding adverse outcomes in patients with OSA. Understanding the pathophysiology of OSA, implementing appropriate preoperative evaluations, and tailoring perioperative management strategies are vital to ensure patient safety and optimize surgical outcomes.

Practice Advisory for Preoperative and Intraoperative Pain Management of Cardiac Surgical Patients: Part 2

Pain after cardiac surgery is of moderate to severe intensity, which increases postoperative distress and health care costs, and affects functional recovery. Opioids have been central agents in treating pain after cardiac surgery for decades. The use of multimodal analgesic strategies can promote effective postoperative pain control and help mitigate opioid exposure. This Practice Advisory is part of a series developed by the Society of Cardiovascular Anesthesiologists (SCA) Quality, Safety, and Leadership (QSL) Committee's Opioid Working Group. It is a systematic review of existing literature for various interventions related to the preoperative and intraoperative pain management of cardiac surgical patients. This Practice Advisory provides recommendations for providers caring for patients undergoing cardiac surgery. This entails developing customized pain management strategies for patients, including preoperative patient evaluation, pain management, and opioid use-focused education as well as perioperative use of multimodal analgesics and regional techniques for various cardiac surgical procedures. The literature related to this field is emerging, and future studies will provide additional guidance on ways to improve clinically meaningful patient outcomes.

The Performance of Opioid-Free Anesthesia for Bariatric Surgery in Clinical Practice

PURPOSE

Opioid-free anesthesia (OFA) is an alternative to conventional opioid-based anesthesia (OBA) in patients undergoing bariatric surgery. Several small studies and a meta-analysis have suggested advantages of OFA for bariatric surgery, but current evidence is still contradictory, and a universally accepted concept has not yet been established. The purpose of this study was to determine whether patients undergoing bariatric surgery experience less postoperative pain and better postoperative recovery when anesthetized with an OFA regimen than with an OBA regimen.

MATERIALS AND METHODS

This prospective observational cohort study, conducted between October 2020 and July 2021, compared patients receiving OFA with patients receiving OBA. Patients were visited 24 and 48 h after the surgical procedure and asked about their postoperative pain using the visual analogue scale (VAS). Additionally, the quality of recovery-40 questionnaire (QoR-40) and the postoperative opioid requirements were recorded.

RESULTS

Ninety-nine patients were included and analyzed in this study (OFA: N = 50; OBA: N = 49). The OFA cohort exhibited less postoperative pain than the OBA cohort within 24 h (VAS median [interquartile range (IQR)]: 2.2 [1-4.4] vs. 4.1 [2-6.5]; P ≤ 0.001) and 48 h (VAS median [IQR]: 1.9 [0.4-4.1] vs. 3.1 [1.4-5.8]; P ≤ 0.001) postoperatively. Additionally, the OFA cohort had higher QoR-40 scores and required less opioid therapy postoperatively.

CONCLUSION

Based on our results the use of OFA for bariatric surgery results in less pain, reduced opioid requirements, and improved postoperative recovery-adding additional evidence regarding the use of OFA in everyday clinical practice.

Can Opioid-Free Anaesthesia Be Personalised? A Narrative Review

Background: A significant amount of evidence suggests that Opioid-Free Anaesthesia (OFA) may provide better outcomes for patients undergoing surgery, sparing patients who are particularly vulnerable to adverse side effects of opioids. However, to what extent personalizing OFA is feasible and beneficial has not been adequately described. Methods: We conducted a narrative literature review aiming to provide a comprehensive understanding of nociception and pain and its context within the field of OFA. Physiological (including monitoring), pharmacological, procedural (type of surgery), genetical and phenotypical (including patients’ conditions) were considered. Results: We did not find any monitoring robustly associated with improved outcomes. However, we found evidence supporting particular OFA indications, such as bariatric and cancer surgery. We found that vulnerable patients may benefit more from OFA, with an interesting field of research in patients suffering from vascular disease. We found a variety of techniques and medications making it impossible to consider OFA as a single technique. Our findings suggest that a vast field of research remains unexplored. In particular, a deeper understanding of nociception with an interest in its genetic and acquired contributors would be an excellent starting point paving the way for personalised OFA. Conclusion: Recent developments in OFA may present a more holistic approach, challenging the use of opioids. Understanding better nociception, given the variety of OFA techniques, may help to maximize their potential in different contexts and potential indications.

Nocturnal respiratory abnormalities among ward-level postoperative patients as detected by the Capnostream 20p monitor: A blinded observational study

PURPOSE

This prospective observational study aimed to establish the frequency of postoperative nocturnal respiratory abnormalities among patients undergoing major surgery who received ward-level care. These abnormalities may have implications for postoperative pulmonary complications (PPCs).

METHODS

Eligible patients underwent blinded noninvasive continuous capnography with pulse oximetry using the Capnostream™ 20p monitor over the first postoperative night. All patients received oxygen supplementation and patient-controlled opioid analgesia. The primary outcome was the number of prolonged apnea events (PAEs), defined as end-tidal carbon dioxide (EtCO2) ≤5 mmHg for 30-120 seconds or EtCO2 ≤5 mmHg for >120 seconds with oxygen saturation (SpO2) <85%. Secondary outcomes were the proportion of recorded time that physiological indices were aberrant, including the apnea index (AI), oxygen desaturation index (ODI), integrated pulmonary index (IPI), and SpO2. Exploratory analysis was conducted to assess the associations between PAEs, PPCs, and pre-defined factors.

RESULTS

Among 125 patients who had sufficient data for analysis, a total of 1800 PAEs occurred in 67 (53.4%) patients. The highest quartile accounted for 89.1% of all events. Amongst patients who experienced any PAEs, the median (IQR) number of PAE/patient was four (2-12). As proportions of recorded time (median (IQR)), AI, ODI, and IPI were aberrant for 12.4% (0-43.2%), 19.1% (2.0-57.1%), and 11.5% (3.1-33.3%) respectively. Only age, ARISCAT, and opioid consumption/kg were associated with PPCs.

CONCLUSIONS

PAE and aberrant indices were frequently detected on the first postoperative night. However, they did not correlate with PPCs. Future research should investigate the significance of detected aberrations.

Respiratory Monitoring after Opioid-Sparing Bariatric Surgery in Patients with Obstructive Sleep Apnea (OSA)

Introduction with Aim: Postoperative respiratory depression can complicate a patient’s recovery after surgery. A predictive score (PRODIGY) was recently proposed to evaluate the risk of opioid-induced postoperative respiratory depression. For the first time, we applied this score to a cohort of patients receiving bariatric surgery, stratified by Obstructive Sleep Apnea (OSA) status. In addition, we recorded continuous postoperative capnography to evaluate respiratory depression and apnea episodes (Respiratory Events, RE). Materials and Methods: The present study was approved by our IRB and comprised continuous surveillance of respiratory variables during postoperative recovery (in PACU) after robotic bariatric surgery. We utilized continuous capnography and pulse oximetry (Capnostream 35, Medtronic Inc., and Profox Respiratory Oximetry software). Preoperative preparation included OSA evaluation for all bariatric patients, additional sleep studies for severe OSA grades, and evaluation of risk for respiratory depression (low, intermediate, or high) using the published PRODIGY score. In addition, we evaluated patients by OSA status. All patients received multimodal intraoperative non-opioid anesthesia from the same team. After surgery, all patients received continuous respiratory surveillance in PACU (average duration exceeding 140 min). Respiratory depression events were scored using a modified list of the five standard published categories. Events were measured according to analysis of continuously recorded tracing of the compiled respiratory variables by observers kept blind from the study patient’s group. Results: Of the 80 patients evaluated (18 male), 56 had obstructive sleep apnea and were using CPAP at home (OSA); 24 did not. OSA patients received CPAP via an oronasal mask or a nasal pillow pressure support immediately after arriving in PACU, utilizing their at-home settings. We encountered 115 respiratory depression events across 48 patients. The most frequent respiratory event recorded was a transient desaturation (as low as 85%), which usually lasted 20–30 sec and resolved spontaneously in 3 to 5 min; most episodes followed small boluses of IV opioid analgesia administered during recovery, on demand. All episodes resolved spontaneously without any nursing or medical intervention. OSA patients had significantly more events than non-OSA patients (1.84 (1.78–1.9) mean events vs. 0.50 (0.43–0.57) for non-OSA, p = 0.0002). The level of PRODIGY score (low, intermediate, or high), instead, was not predictive of the number of events when we treated this variable as continuous (p = 0.39) or categorical (high vs. low, p = 0.65, and intermediate vs. low, p = 0.17). Conclusions: We attribute these novel results, showing a lack of respiratory events requiring intervention, to opioid-free anesthesia, early CPAP utilization, and head-up positioning on admission to PACU. Furthermore, all these patients had light postoperative narcotic requirements. Finally, an elevated PRODIGY score in our patients did not sufficiently predict respiratory events, but OSA status alone did. Key Points Summary: We investigated the incidence of Respiratory Events (RE) in Obstructive Sleep Apnea patients after surgery (56 patients) and compared them to similar patients without OSA (24 patients). All patients received identical robotic-assisted surgery and low- or no-opiate anesthesia. Patients were pre-screened with the standard published PRODIGY scores and were monitored after PACU arrival with continuous oximetry and capnography (Capnostream 35 and Profox analysis). OSA patients showed more RE than non-OSA (1.8 vs. 0.5, p = −0.0002). However, patients with elevated PRODIGY scores did not develop more frequent RE compared to patients with low scores. We attribute these novel results to opioid-sparing anesthesia/analgesia and immediate CPAP utilization on admission to PACU.

Review of Postoperative Respiratory Depression: From Recovery Room to General Care Unit

Contemporary evidence suggests that episodes of respiratory depression during anesthesia recovery are associated with subsequent respiratory complications in general care units.

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.

Developing a risk stratification tool for predicting opioid-related respiratory depression after non-cardiac surgery: a retrospective study

OBJECTIVES

Accurately assessing the probability of significant respiratory depression following opioid administration can potentially enhance perioperative risk assessment and pain management. We developed and validated a risk prediction tool to estimate the probability of significant respiratory depression (indexed by naloxone administration) in patients undergoing noncardiac surgery.

DESIGN

Retrospective cohort study.

SETTING

Single academic centre.

PARTICIPANTS

We studied n=63 084 patients (mean age 47.1±18.2 years; 50% men) who underwent emergency or elective non-cardiac surgery between 1 January 2007 and 30 October 2017.

INTERVENTIONS

A derivation subsample reflecting two-thirds of available patients (n=42 082) was randomly selected for model development, and associations were identified between predictor variables and naloxone administration occurring within 5 days following surgery. The resulting probability model for predicting naloxone administration was then cross-validated in a separate validation cohort reflecting the remaining one-third of patients (n=21 002).

RESULTS

The rate of naloxone administration was identical in the derivation (n=2720 (6.5%)) and validation (n=1360 (6.5%)) cohorts. The risk prediction model identified female sex (OR: 3.01; 95% CI: 2.73 to 3.32), high-risk surgical procedures (OR: 4.16; 95% CI: 3.78 to 4.58), history of drug abuse (OR: 1.81; 95% CI: 1.52 to 2.16) and any opioids being administered on a scheduled rather than as-needed basis (OR: 8.31; 95% CI: 7.26 to 9.51) as risk factors for naloxone administration. Advanced age (OR: 0.971; 95% CI: 0.968 to 0.973), opioids administered via patient-controlled analgesia pump (OR: 0.55; 95% CI: 0.49 to 0.62) and any scheduled non-opioids (OR: 0.63; 95% CI: 0.58 to 0.69) were associated with decreased risk of naloxone administration. An overall risk prediction model incorporating the common clinically available variables above displayed excellent discriminative ability in both the derivation and validation cohorts (c-index=0.820 and 0.814, respectively).

CONCLUSION

Our cross-validated clinical predictive model accurately estimates the risk of serious opioid-related respiratory depression requiring naloxone administration in postoperative patients.

Risk factors for opioid toxicity requiring naloxone rescue in adults: a case-control study

BACKGROUND

Opioid-induced sedation and respiratory depression (OSRD) is a potentially life-threatening side effect of opioid analgesia. However, little is known about the individual and clinical-related factors associated with OSRD in the New Zealand context.

AIM

To identify risk factors for OSRD in patients admitted to a large regional health board in New Zealand-Auckland District Health Board (ADHB).

METHOD

A retrospective matched case-control study design was undertaken among adults who were admitted to ADHB and prescribed opioids in hospital between August 2015 and April 2020. Those who were prescribed opioids and received naloxone for OSRD were defined as cases, whereas those who received opioids but did not experience OSRD were identified as controls. Cases and controls were matched on a 1:1 basis by age (± 10 years). Data were retrieved from the electronic medical records of ADHB. A conditional logistic regression model was used to identify the risk factors for OSRD.

RESULTS

We identified 51 cases, and these were matched with 51 control patients. The odds of experiencing OSRD were four times higher among opioid-naïve patients compared to those exposed to opioids prior to hospital admission (OR  4.113; 95% CI 1.14-14.89). Increased risk of OSRD was also associated with higher serum creatinine level prior to OSRD episode (OR 1.015; 95% CI 1.01-1.03) and a higher oral morphine milligram equivalent (OME) (OR 1.023; 95% CI 1.01-1.04).

CONCLUSION

Increased risk of OSRD was associated with a higher OME, a higher serum creatinine level prior to OSRD episode, and opioid naivety. Our findings can inform policies that aim to prevent serious adverse effects related to opioids.

Morphine-3-Glucuronide, Physiology and Behavior

Morphine remains the gold standard painkiller available to date to relieve severe pain. Morphine metabolism leads to the production of two predominant metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). This metabolism involves uridine 5'-diphospho-glucuronosyltransferases (UGTs), which catalyze the addition of a glucuronide moiety onto the C3 or C6 position of morphine. Interestingly, M3G and M6G have been shown to be biologically active. On the one hand, M6G produces potent analgesia in rodents and humans. On the other hand, M3G provokes a state of strong excitation in rodents, characterized by thermal hyperalgesia and tactile allodynia. Its coadministration with morphine or M6G also reduces the resulting analgesia. Although these behavioral effects show quite consistency in rodents, M3G effects are much more debated in humans and the identity of the receptor(s) on which M3G acts remains unclear. Indeed, M3G has little affinity for mu opioid receptor (MOR) (on which morphine binds) and its effects are retained in the presence of naloxone or naltrexone, two non-selective MOR antagonists. Paradoxically, MOR seems to be essential to M3G effects. In contrast, several studies proposed that TLR4 could mediate M3G effects since this receptor also appears to be essential to M3G-induced hyperalgesia. This review summarizes M3G's behavioral effects and potential targets in the central nervous system, as well as the mechanisms by which it might oppose analgesia.

OSA and Chronic Respiratory Disease: Mechanisms and Epidemiology

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

The effect of continuous intercostal nerve block vs. single shot on analgesic outcomes and hospital stays in minimally invasive direct coronary artery bypass surgery: a retrospective cohort study

BACKGROUND

Minimally invasive direct coronary artery bypass (MIDCAB) grafting surgery is accompanied by severe pain. Although continuous intercostal nerve block (CINB) has become one of the multimodal analgesic techniques in single port thoracoscopic surgery, its effects on MIDCAB are unclear. The purpose of this study was to compare the effects of CINB and single shot on analgesic outcomes and hospital stays in patients undergoing MIDCAB in a real-world setting.

METHODS

A retrospective cohort study was carried out at Peking University Third Hospital, China. Two hundred and sixteen patients undergoing MIDCAB were divided into two groups: a CINB group and a single block (SI) group. The primary outcome was postoperative maximal visual analog scale (VAS); secondary outcomes included the number of patients with maximal VAS ≤ 3, the demand for and consumed doses of pethidine and tramadol, and the length of intensive care unit (ICU) and hospital stays. The above data and the area under the VAS curve in the 70 h after extubation for the two subgroups (No. of grafts = 1) were also compared.

RESULTS

The maximum VAS was lower in the CINB group, and there were more cases with maximum VAS ≤ 3 in the CINB group: CINB 52 (40%) vs. SI 17 (20%), P = 0.002. The percentage of cases requiring tramadol and pethidine was less in CINB, P = 0.001. Among all patients, drug doses were significantly lower in the CINB group [tramadol: CINB 0 (0-100) mg vs. SI 100 (0-225) mg, P = 0.0001; pethidine: CINB 0 (0-25) mg vs. SI 25 (0-50) mg, P = 0.0004]. Further subgroup analysis showed that the area under the VAS curve in CINB was smaller: 28.05 in CINB vs. 30.41 in SI, P = 0.002. Finally, the length of ICU stay was shorter in CINB than in SI: 20.5 (11.3-26.0) h vs. 22.0 (19.0-45.0) h, P = 0.011.

CONCLUSIONS

CINB is associated with decreased demand for rescue analgesics and shorter length of ICU stay when compared to single shot intercostal nerve block. Additional randomized controlled trial (RCT) is needed to support these findings.

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.

Current Issues in the Use of Opioids for the Management of Postoperative Pain: A Review

Importance

Uncontrolled and indiscriminate prescribing of opioids has led to an opioid crisis that started in North America and spread throughout high-income countries. The aim of this narrative review was to explore some of the current issues surrounding the use of opioids in the perioperative period, focusing on drivers that led to escalation of use, patient harms, the move away from using self-reported pain scores alone to assess adequacy of analgesia, concerns about the routine use of controlled-release opioids for the management of acute pain, opioid-free anesthesia and analgesia, and prescription of opioids on discharge from hospital.

Observations

The origins of the opioid crisis are multifactorial and may include good intentions to keep patients pain free in the postoperative period. Assessment of patient function may be better than unidimensional numerical pain scores to help guide postoperative analgesia. Immediate-release opioids can be titrated more easily to match analgesic requirements. There is currently no good evidence to show that opioid-free anesthesia and analgesia affects opioid prescribing practices or the risk of persistent postoperative opioid use. Attention should be paid to discharge opioid prescribing as repeat and refill prescriptions are risk-factors for persistent postoperative opioid use. Opioid stewardship is paramount, and many governments are passing legislation, while statutory bodies and professional societies are providing advice and guidance to help mitigate the harm caused by opioids.

Conclusions and Relevance

Opioids remain a crucial part of many patients' journey from surgery to full recovery. The last few decades have shown that unfettered opioid use puts patients and societies at risk, so caution is needed to mitigate those dangers. Opioid stewardship provides a multilayered structure to allow continued safe use of opioids as part of broad pain management strategies for those patients who benefit from them most.

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.