Multimodal Analgesic Therapy With Gabapentin and Its Association With Postoperative Respiratory Depression

Perioperative Management of the Patient With Obstructive Sleep Apnea: A Narrative Review

The prevalence of obstructive sleep apnea (OSA) has reached 1 billion people worldwide, implying significant risk for the perioperative setting as patients are vulnerable to cardiopulmonary complications, critical care requirement, and unexpected death. This review summarizes main aspects and considerations for the perioperative management of OSA, a condition of public health concern. Critical determinants of perioperative risk include OSA-related changes in upper airway anatomy with augmented collapsibility, diminished capability of upper airway dilator muscles to respond to airway obstruction, disparities in hypoxemia and hypercarbia arousal thresholds, and instability of ventilatory control. Preoperative OSA screening to identify patients at increased risk has therefore been implemented in many institutions. Experts recommend that in the absence of severe symptoms or additional compounding health risks, patients may nevertheless proceed to surgery, while heightened awareness and the adjustment of postoperative care is required. Perioperative caregivers should anticipate difficult airway management in OSA and be prepared for airway complications. Anesthetic and sedative drug agents worsen upper airway collapsibility and depress central respiratory activity, while the risk for postoperative respiratory compromise is further increased with the utilization of neuromuscular blockade. Consistently, opioid analgesia has proven to be complex in OSA, as patients are particularly prone to opioid-induced respiratory depression. Moreover, basic features of OSA, including intermittent hypoxemia and repetitive sleep fragmentation, gradually precipitate a higher sensitivity to opioid analgesic potency along with an increased perception of pain. Hence, regional anesthesia by blockade of neural pathways directly at the site of surgical trauma as well as multimodal analgesia by facilitating additive and synergistic analgesic effects are both strongly supported in the literature as interventions that may reduce perioperative complication risk. Health care institutions are increasingly allocating resources, including those of postoperative enhanced monitoring, in an effort to increase patient safety. The implementation of evidence-based perioperative management strategies is however burdened by the rising prevalence of OSA, the large heterogeneity in disease severity, and the lack of evidence on the efficacy of costly perioperative measures. Screening and monitoring algorithms, as well as reliable risk predictors, are urgently needed to identify OSA patients that are truly in need of extended postoperative surveillance and care. The perioperative community is therefore challenged to develop feasible pathways and measures that can confer increased patient safety and prevent complications in patients with OSA.

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

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

Association of gabapentinoid utilization with postoperative pulmonary complications in gynecologic surgery: a retrospective cohort study

OBJECTIVE

To investigate gabapentinoid utilization and association with postoperative pulmonary complications after gynecologic surgery.

METHODS

After Institutional Review Board approval, we performed this retrospective cohort study using the Premier Healthcare Database. We used ICD-10 and charge codes to identify adults who underwent elective gynecologic surgery from 2015 to 2018 and received either gabapentin or pregabalin on the day of surgery. Our primary outcome was a composite of pulmonary complications: respiratory failure, pneumonia, reintubation, pulmonary edema, and non-invasive or invasive ventilation. Secondary outcomes included mortality, intensive care unit admission, mechanical or non-invasive ventilation, hospital length of stay, re-admission within 30 days, opioid consumption and antiemetic use. Multivariable generalized linear mixed models were utilized to examine the associations between gabapentinoids and our outcome measures, adjusted for all covariates.

RESULTS

Data from 253,013 patients were analyzed, with 19,121 (7.6%) receiving gabapentinoids. Gabapentinoid utilization increased from 3.9% in 2015 to 12.3% in 2018, and was associated with increased pulmonary complications (OR 1.19; 95% CI 1.03-1.38), non-invasive ventilation (odds ratio [OR] 1.53; 95% CI 1.29-1.81), duration of hospital stay (% change 1.75; 95% CI 0.92-2.59), daily antiemetic doses on day of surgery (mean difference [MD] 1.37; 95% CI 1.26-1.49) and subsequently (MD 1.61; 95% CI 1.30-1.99), and higher daily average (MD 4.59 mg; 95% CI 3.55-5.63) and total (MD 8.74 mg; 95% CI 6.83-10.62) parenteral morphine equivalents.

CONCLUSIONS

Gabapentinoid utilization in gynecologic surgery is increasing and is associated with postoperative pulmonary complications.

Perioperative Opioid Administration

Opioids form an important component of general anesthesia and perioperative analgesia. Discharge opioid prescriptions are identified as a contributor for persistent opioid use and diversion. In parallel, there is increased enthusiasm to advocate opioid-free strategies, which include a combination of known analgesics and adjuvants, many of which are in the form of continuous infusions. This article critically reviews perioperative opioid use, especially in view of opioid-sparing versus opioid-free strategies. The data indicate that opioid-free strategies, however noble in their cause, do not fully acknowledge the limitations and gaps within the existing evidence and clinical practice considerations. Moreover, they do not allow analgesic titration based on patient needs; are unclear about optimal components and their role in different surgical settings and perioperative phases; and do not serve to decrease the risk of persistent opioid use, thereby distracting us from optimizing pain and minimizing realistic long-term harms.

Respiratory depression in the post-anesthesia care unit: Mayo Clinic experience

The anesthesia recovery is a complex physiologic process as systems recover from the effects of surgery and anesthesia. Inadequate recovery of respiratory physiology can lead to severe hypoxemia-induced end-organ damage and even death. Emerging evidence suggests that signs of respiratory depression during early anesthesia recovery may portend increased risk for future severe adverse events. This article briefly reviews the Mayo Clinic research experience and advances in clinical practice. From the implementation of a step-down model of discharge criteria in the post-anesthesia care unit (PACU), consisting of PACU nurses monitoring patients in predetermined periods for signs of respiratory depression, and delaying PACU discharge for patients who exhibit signs of respiratory depression, and early intervention in high-risk patients. Subsequent studies found that even a single episode of respiratory depression in the PACU was strongly associated with subsequent respiratory complications. Further, patient baseline characteristics found to be associated with respiratory depression included obstructive sleep apnea and low body weight, and surgical factors associated with increased risk included the use of preoperative sustained-release opioids, perioperative gabapentinoid use, higher intraoperative opioids, isoflurane as the volatile anesthetic, and longer surgical duration. Based in part of Mayo Clinic research, the FDA issued a warning in 2019 on gabapentinoids use and respiratory complications, increasing the recommended level of respiratory vigilance in patients using this medication. Understanding the complex nature of postoperative respiratory events requires a range of translational and clinical research and constant update of practice.

An international multidisciplinary consensus statement on the prevention of opioid-related harm in adult surgical patients

This international multidisciplinary consensus statement was developed to provide balanced guidance on the safe peri-operative use of opioids in adults. An international panel of healthcare professionals evaluated the literature relating to postoperative opioid-related harm, including persistent postoperative opioid use; opioid-induced ventilatory impairment; non-medical opioid use; opioid diversion and dependence; and driving under the influence of prescription opioids. Recommended strategies to reduce harm include pre-operative assessment of the risk of persistent postoperative opioid use; use of an assessment of patient function rather than unidimensional pain scores alone to guide adequacy of analgesia; avoidance of long-acting (modified-release and transdermal patches) opioid formulations and combination analgesics; limiting the number of tablets prescribed at discharge; providing deprescribing advice; avoidance of automatic prescription refills; safe disposal of unused medicines; reducing the risk of opioid diversion; and better education of healthcare professionals, patients and carers. This consensus statement provides a framework for better prescribing practices that could help reduce the risk of postoperative opioid-related harm in adults.

Safety of treatment options available for postoperative pain

IntroductionPostoperative pain is one of the most common adverse events after surgery and has been shown to increase the risk of other complications. On the other hand, liberal opioid use in the perioperative period is also associated with risk of adverse events. The current consensus is therefore to provide multimodal, opioid minimizing analgesia after surgery.Areas CoveredIn this review, we will discuss the benefits and risks associated with non-opioid analgesics, including non-steroidal anti-inflammatory drugs, gabapentinoids, ketamine, α-2 agonists, and corticosteroids. In addition, we will discuss the general and block-specific risks associated with regional anesthestic techniques.Expert OpinionAdverse events associated with non-opioid analgesics are rare outside their specific contraindicated patient groups, especially when dosed appropriately. α-2 agonists can cause transient hypotension and bradycardia, and gabapentinoids may cause sedation in higher risk patient populations. Regional anesthesia techniques are generally safe when done by an experienced practitioner. We therefore encourage the development of standardized multimodal analgesic protocols, which may facilitate opioid minimization and lead to better patient outcomes.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

Reduction in Opiate Use, Pain, Nausea, and Length of Stay After Implementation of a Bariatric Enhanced Recovery After Surgery Protocol

PURPOSE

Evaluate adherence to bariatric surgery enhanced recovery after surgery (ERAS) protocols in pre-operative, operative, and post-operative phases, and to compare opiate use, nausea control, and length of stay (LOS) versus historical controls.

MATERIALS AND METHODS

A retrospective, observational cohort study was conducted to evaluate adherence to ERAS protocols and compare opiate and antiemetic use, pain intensity, and LOS versus those of traditional care (TC) patients preceding protocol implementation at Erie County Medical Center, a community-based hospital in Buffalo, NY, USA.

RESULTS

One hundred ERAS and TC patients were compared. Patients were similar in age (42.5 years), gender (female, ~ 80%), race (~ 80 white), and BMI (47 kg/m²). The primary procedure performed was sleeve gastrectomy (89% ERAS, 86% TC). Protocol adherence was high for ERAS phases: prior to admission (85-98%), pre-operative (96-100%), operative (93-99%), post-anesthesia care unit (PACU) (55-61%), and floor (86-98%). Opiate morphine milligram equivalent (MME) was reduced in ERAS vs. TC in hospital by 73% (43.5 ± 42.4 vs. 160 ± 116; p < 0.001), discharge prescribing by 53% (34.8 ± 38.2 vs. 74 ± 125 MME; p = 0.003), and in total by 69% (78.3 ± 67.5 vs. 252 ± 160; p < 0.001). Despite lower opiate use, ERAS had lower pain intensity entering PACU (1.1 ± 1.8 vs. 1.9 ± 2.6; p < 0.011), leaving PACU (1.7 ± 1.5 vs. 2.9 ± 1.5; p < 0.001), and floor day 0 (5.0 ± 2.1 vs. 5.9 ± 1.8; p < 0.001). Fewer ERAS required antiemetic day 0 (63% vs. 94%; p < 0.001). ERAS were discharged in fewer hours than TC (41.1 ± 15.5 vs. 52.1 ± 18.9 h; p < 0.001).

CONCLUSIONS

Bariatric surgery ERAS protocols were implemented with a high rate of adherence and yielded profound reduction in operative and post-operative opiate use while improving pain control and nausea management in hospital and decreasing LOS.

Trends in new prescription of gabapentinoids and of coprescription with opioids in the 4 nations of the UK, 1993-2017

We explored potential differences in time trends of gabapentinoid prescription and of opioid coprescription between 1993 and 2017 in the 4 UK nations using the Clinical Practice Research Datalink, a UK primary care database. There were distinct trends in annual rates of new gabapentin and pregabalin prescriptions in Northern Ireland. The rate of new gabapentin prescriptions rapidly increased after 2010 and exceeded that of the other nations by 2017 (rate of 836 [95% confidence interval: 787-887] per 100 000 person-years). Additionally, the rate of new pregabalin prescriptions was higher during the entire study period, reaching a peak of 1139 (95% confidence interval: 1088-1193) per 100 000 person-years in 2010, 5-fold higher than the other nations. Findings in Northern Ireland may be partly attributable to the high burden of anxiety disorders, an indication for pregabalin. Further exploration of reasons for discrepancies in gabapentinoid prescribing between UK nations is warranted.

PROSPECT guideline for elective caesarean section: updated systematic review and procedure-specific postoperative pain management recommendations

Caesarean section is associated with moderate‐to‐severe postoperative pain, which can influence postoperative recovery and patient satisfaction as well as breastfeeding success and mother‐child bonding. The aim of this systematic review was to update the available literature and develop recommendations for optimal pain management after elective caesarean section under neuraxial anaesthesia. A systematic review utilising procedure‐specific postoperative pain management (PROSPECT) methodology was undertaken. Randomised controlled trials published in the English language between 1 May 2014 and 22 October 2020 evaluating the effects of analgesic, anaesthetic and surgical interventions were retrieved from MEDLINE, Embase and Cochrane databases. Studies evaluating pain management for emergency or unplanned operative deliveries or caesarean section performed under general anaesthesia were excluded. A total of 145 studies met the inclusion criteria. For patients undergoing elective caesarean section performed under neuraxial anaesthesia, recommendations include intrathecal morphine 50–100 µg or diamorphine 300 µg administered pre‐operatively; paracetamol; non‐steroidal anti‐inflammatory drugs; and intravenous dexamethasone administered after delivery. If intrathecal opioid was not administered, single‐injection local anaesthetic wound infiltration; continuous wound local anaesthetic infusion; and/or fascial plane blocks such as transversus abdominis plane or quadratus lumborum blocks are recommended. The postoperative regimen should include regular paracetamol and non‐steroidal anti‐inflammatory drugs with opioids used for rescue. The surgical technique should include a Joel‐Cohen incision; non‐closure of the peritoneum; and abdominal binders. Transcutaneous electrical nerve stimulation could be used as analgesic adjunct. Some of the interventions, although effective, carry risks, and consequentially were omitted from the recommendations. Some interventions were not recommended due to insufficient, inconsistent or lack of evidence. Of note, these recommendations may not be applicable to unplanned deliveries or caesarean section performed under general anaesthesia.

Association of Gabapentinoids With the Risk of Opioid-Related Adverse Events in Surgical Patients in the United States

IMPORTANCE

The use of gabapentinoids in multimodal postoperative analgesia is increasing; however, when coadministered with opioids, these drugs may potentiate central nervous system and respiratory depression.

OBJECTIVE

To evaluate the association between perioperative coadministration of gabapentinoids and opioids with inpatient opioid-related adverse events in surgical patients.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used propensity score trimming, stratification, and weighting of adults admitted for a major surgery between October 2007 and December 2017 who were treated with opioids on the day of surgery and included in the Premier Research database. Data analysis was conducted from February to April 2020.

EXPOSURE

Gabapentinoids (gabapentin or pregabalin) coadministered with opioids starting the day of surgery vs opioid therapy without gabapentinoids.

MAIN OUTCOMES AND MEASURES

Primary outcome was opioid overdose. Secondary outcomes included respiratory complications, unspecified adverse effects of opioid use, and a composite of these 3 outcomes. Patients were followed up for as long as 30 days from the day of surgery until deviation from the initial treatment regimen or discharge.

RESULTS

Gabapentinoids with opioids were administered to 892 484 of 5 547 667 eligible admissions (16.1%; mean [SD] age, 63.5 [11.8] years; 353 315 [39.6%] men). Among the 4 655 183 patients who received opioids only, the mean (SD) age was 63.7 (14.7) years, and 1 913 284 (41.1%) were men. Overall, 441 overdose events were identified, with absolute risks of 1.4 per 10 000 patients with gabapentinoid exposure and 0.7 per 10 000 patients receiving opioids only. Following propensity score trimming, the cohort included 737 383 patients exposed to gabapentinoids and 3 002 480 patients receiving opioids only. The primary analysis yielded the adjusted hazard ratio of 1.95 (95% CI, 1.49-2.55), and the number needed to treat for an additional overdose to occur was 16 914 patients (95% CI, 11 556-31 537 patients). Adjusted hazard ratios for secondary outcomes were 1.68 (95% CI, 1.59-1.78) for respiratory complications, 1.77 (95% CI, 1.61-1.93) for unspecified adverse effects of opioids, and 1.70 (95% CI, 1.62-1.79) for the composite outcome. The results were consistent across sensitivity analyses and subgroups identified by key clinical factors.

CONCLUSIONS AND RELEVANCE

In this real-world cohort study of patients who underwent major surgery, concomitant use of gabapentinoids with opioids was associated with increased risk of opioid overdose and other opioid-related adverse events; however, the absolute risk of adverse events was low.

Methadone and a Clinical Pathway in Adolescent Idiopathic Scoliosis Surgery: A Historically Controlled Study

STUDY DESIGN

Historically controlled clinical trial.

OBJECTIVES

Patients presenting for correction of adolescent idiopathic scoliosis (AIS) by posterior spinal fusion may benefit from structured clinical pathways. We studied the effects of implementing a published clinical pathway for the perioperative care of patients with AIS that required intraoperative use of methadone at our institution.

METHODS

We performed a historically controlled clinical trial of patients undergoing posterior spinal fusion for AIS by comparing a retrospectively collected control group of 25 patients with a prospective experimental group of 14 patients receiving methadone, gabapentin, propofol, and remifentanil as part of a new clinical pathway.

RESULTS

Use of the pathway decreased average pain scores evaluated by the Numeric Rating Scale in the 24 hours following surgery (4.8 [4-6] to 3.4 [2-4], P = .03 [-2.6 to -0.2; t = -2.3]) and postoperative opioid consumption by 76% (41 [29-51] mg to 10 [4-17] mg, P < .001 [-45 to -15; Welch's t = 4.9]) during the same period. Improved analgesia and reduced reliance on opioids facilitated other postoperative elements of the clinical pathway and shortened the average hospital length of stay by 1 day (4 [3-6] days to 3 [3-5] days, P = .001 [-2 to -1; U = 67, Z = -3.3]).

CONCLUSIONS

Multimodal analgesia and a clinical pathway add value in the perioperative care of patients undergoing posterior spinal fusion for AIS by improving analgesia and shortening hospitalization. The prospective arm of the trial was registered at clinicaltrials.gov under NCT02481570.

Optimizing Perioperative Use of Opioids: A Multimodal Approach

Purpose of Review

The main purpose of this article is to review recent literature regarding multimodal analgesia medications, citing their recommended doses, efficacy, and side effects. The second part of this report will provide a description of drugs in different stages of development which have novel mechanisms with less side effects such as tolerance and addiction.

Recent Findings

Multimodal analgesia is a technique that facilitates perioperative pain management by employing two or more systemic analgesics along with regional anesthesia, when possible. Even though opioids and non-opioid analgesics remain the most common medication used for acute pain management after surgery, they have many undesirable side effects including the potential for misuse. Newer analgesics including peripheral acting opioids, nitric oxide inhibitors, calcitonin gene-related peptide receptor antagonists, interleukin-6 receptor antagonists and gene therapy are under intensive investigation.

Summary

A patient's first exposure to opioids is often in the perioperative setting, a vulnerable time when multimodal therapy can play a large role in decreasing opioid exposure. Additionally, the current shift towards faster recovery times, fewer post-operative complications and improved cost-effectiveness during the perioperative period has made multimodal analgesia a central pillar of Enhanced Recovery After Surgery (ERAS) protocols.

Multimorbidity and Critical Care Neurosurgery: Minimizing Major Perioperative Cardiopulmonary Complications

With increasing prevalence of chronic diseases, multimorbid patients have become commonplace in the neurosurgical intensive care unit (neuro-ICU), offering unique management challenges. By reducing physiological reserve and interacting with one another, chronic comorbidities pose a greatly enhanced risk of major postoperative medical complications, especially cardiopulmonary complications, which ultimately exert a negative impact on neurosurgical outcomes. These premises underscore the importance of perioperative optimization, in turn requiring a thorough preoperative risk stratification, a basic understanding of a multimorbid patient’s deranged physiology and a proper appreciation of the potential of surgery, anesthesia and neurocritical care interventions to exacerbate comorbid pathophysiologies. This knowledge enables neurosurgeons, neuroanesthesiologists and neurointensivists to function with a heightened level of vigilance in the care of these high-risk patients and can inform the perioperative neuro-ICU management with individualized strategies able to minimize the risk of untoward outcomes. This review highlights potential pitfalls in the intra- and postoperative neuro-ICU period, describes common preoperative risk stratification tools and discusses tailored perioperative ICU management strategies in multimorbid neurosurgical patients, with a special focus on approaches geared toward the minimization of postoperative cardiopulmonary complications and unplanned reintubation.

Pain Management in Breast Surgery: Recommendations of a Multidisciplinary Expert Panel-The American Society of Breast Surgeons

Opioid overdose accounted for more than 47,000 deaths in the United States in 2018. The risk of new persistent opioid use following breast cancer surgery is significant, with up to 10% of patients continuing to fill opioid prescriptions one year after surgery. Over prescription of opioids is far too common. A recent study suggested that up to 80% of patients receiving a prescription for opioids post-operatively do not need them (either do not fill the prescription or do not use the medication). In order to address this important issue, The American Society of Breast Surgeons empaneled an inter-disciplinary committee to develop a consensus statement on pain control for patients undergoing breast surgery. Representatives were nominated by the American College of Surgeons, the Society of Surgical Oncology, The American Society of Plastic Surgeons, and The American Society of Anesthesiologists. A broad literature review followed by a more focused review was performed by the inter-disciplinary panel which was comprised of 14 experts in the fields of breast surgery, anesthesiology, plastic surgery, rehabilitation medicine, and addiction medicine. Through a process of multiple revisions, a consensus was developed, resulting in the outline for decreased opioid use in patients undergoing breast surgery presented in this manuscript. The final document was reviewed and approved by the Board of Directors of the American Society of Breast Surgeons.

Frequency of Concomitant Use of Gabapentinoids and Opioids among Patients with Cancer-Related Pain at an Outpatient Palliative Care Clinic

Background: Patients with cancer-related pain use opioids for nociceptive pain, while gabapentinoids are common to treat neuropathic pain. The simultaneous use of opioids with gabapentinoids has been associated with an increased risk of opioid-related death. Objectives: Determine the frequency of combined use of gabapentinoids among patients receiving opioids for cancer-related pain. We also examined if concomitant use of opioids and gabapentinoids together was associated with increased scores of fatigue and drowsiness on the Edmonton Symptom Assessment Scale (ESAS) compared to patients on opioids. Design: Retrospective study of patients on opioids and opioids plus gabapentinoids at their third visit to the outpatient Supportive Care Center. Results: We found that 48% (508/1059) of patients were on opioids. Of these patients, 51% (257/508) were on opioids only, and 49% (251/508) were on opioids plus gabapentinoids. The median (interquartile range [IQR]) morphine equivalent daily dose for patients on opioids was 75 (45, 138) mg, and opioids plus gabapentinoids was 68 (38, 150) mg (p = 0.94). The median (IQR) gabapentinoid equivalent daily dose was 900 (300, 1200) mg. The median (IQR) for ESAS-fatigue in patients on opioids was 5 (3, 7), and opioids plus gabapentinoids was 5 (3, 7) (p = 0.27). The median (IQR) for ESAS-drowsiness in patients on opioids was 3 (0, 5), and opioids plus gabapentinoids was 3 (0, 6) (p = 0.11). Conclusion: Almost 50% of advanced cancer patients receiving opioids for pain were exposed to gabapentinoids. Maximal efforts should be made to minimize potential complications from the concomitant use of opioids with gabapentinoids.

Multimodal Pain Management and Postoperative Outcomes in Lumbar Spine Fusion Surgery: A Population-based Cohort Study

STUDY DESIGN

Retrospective population-based cohort analysis.

OBJECTIVE

Given the lack of large-scale data on the use and efficacy of multimodal analgesia in spine fusion surgery, we conducted a population-based analysis utilizing the nationwide claims-based Premier Healthcare database.

SUMMARY OF BACKGROUND DATA

Multimodal analgesia, combining different pain signaling pathways to achieve additive and synergistic effects, is increasingly emerging as the standard of care.

METHODS

Cases of posterior lumbar fusion surgery were extracted (2006-2016). Opioid-only analgesia was compared to multimodal analgesia, that is, systemic opioid analgesia + either acetaminophen, steroids, gabapentinoids, ketamine, nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, or neuraxial anesthesia (categorized into 1, 2, or >2 additional analgesic modes). Mixed-effects models measured associations between multimodal analgesia categories and outcomes, including opioid prescription dose, cost/length of hospitalization, and opioid-related complications. Odds ratios (ORs, or % change) and 95% confidence intervals (CIs) are reported.

RESULTS

Among 265,538 patients the incidence of multimodal analgesia was 61.1% (162,156); multimodal pain management-specifically when adding NSAIDs/COX-2 inhibitors to opioids-was associated with reduced opioid prescription (-13.3% CI -16.7 to -9.7%), cost (-2.9% CI -3.9 to -1.8%) and length of hospitalization (-7.3% CI -8.5 to -6.1%). Multimodal analgesia in general was associated with stepwise decreased odds for gastrointestinal complications (OR 0.95, 95% CI 0.88-1.04; OR 0.84, CI 0.75-0.95; OR 0.78, 95% CI 0.64-0.96), whereas odds were increased for postoperative delirium (OR 1.14, 95% CI 1.00-1.32; OR 1.33, 95% CI 1.11-1.59; OR 1.31, 95% CI 0.99-1.74), and counterintuitively- naloxone administration (OR 1.25, 95% CI 1.13-1.38; OR 1.56, 95% CI 1.37-1.77; OR 1.84, 95% CI 1.52-2.23) with increasing analgesic modes used: one, two, or more additional analgesic modes, respectively. Post-hoc analysis revealed that specifically gabapentinoid use increased odds of naloxone requirement by about 50%, regardless of concurrent opioid dose (P < 0.001).

CONCLUSION

Although multimodal analgesia was not consistently implemented in spine fusion surgery, particularly NSAIDs and COX-2 inhibitors demonstrated opioid sparing effects. Moreover, results suggest a synergistic interaction between gabapentinoids and opioids, the former potentiating opioid effects resulting in greater naloxone requirement.

LEVEL OF EVIDENCE

3.

Anesthesia for TORS for Oropharyngeal Carcinoma: Factors Associated with Prolonged Phase I Postanesthesia Recovery

OBJECTIVES

Clinical variables affecting anesthetic recovery following transoral robotic surgery (TORS) to resect oropharyngeal squamous cell carcinoma have not been described. We aimed to explore risk factors associated with prolonged postanesthesia recovery following TORS.

STUDY DESIGN

Retrospective case-control study.

SETTING

Tertiary referral center, January 2010 to November 2016.

SUBJECTS AND METHODS

Patients included adults undergoing primary TORS ± neck dissection for oropharyngeal squamous cell carcinoma. Patients were categorized by phase I recovery time into the "goal" recovery group (75th percentile [lower 3 quartiles], n = 272) and the "prolonged" recovery group (n = 91). Univariate and multivariate logistic regression analyses were performed to assess the associations between clinical characteristics and prolonged phase I recovery.

RESULTS

A total of 363 patients were included. Median (interquartile range) duration of postanesthesia recovery was 1.5 hours (1.0-2.0). Prolonged recovery was associated with isoflurane (odds ratio, 2.83 [95% CI, 1.56-5.14], P < .001), midazolam (2.77 [1.50-5.12], P = .001), and larger opioid doses (1.26 [1.01-1.58] per 10-mg intravenous morphine equivalents, P = .040) and inversely associated with multimodal antiemetic therapy (0.34 [0.15-0.78], P = .011). Prolonged cases had higher rates of postoperative nausea and vomiting (n = 43 [47.2%] vs 86 [31.6%], P = .008), respiratory depression (28 [30.8%] vs 12 [4.4%], P < .001), sedation (Richmond Agitation-Sedation Scale < -2; 26 [28.6%] vs 35 [12.9%], P = .001), severe pain (numeric rating score ≥7; 31 [34.4%] vs 45 [17.2%], P = .001), and longer hospital stays (4 vs 3 days, P < .001).

CONCLUSIONS

Several anesthetic factors are associated with anesthesia recovery duration, which may be shortened by efforts to reduce postoperative sedation, severe pain, and nausea/vomiting. Shortened anesthesia recovery time may reduce hospital stay.

Preoperative cognitive impairment associated with oversedation during recovery from anesthesia

PURPOSE

Our objective was to examine the association between preoperative cognitive status and postoperative recovery from anesthesia.

METHODS

We included patients (70-91 years old) from the Mayo Clinic Study of Aging who received general anesthesia and were admitted to the postanesthesia care unit from January 1, 2010 through April 30, 2018. Procedures were categorized according to patient's preoperative cognitive status: cognitive impaired (CI) and cognitive unimpaired (CU). Perioperative records were reviewed and analyses were performed with generalized estimating equations.

RESULTS

A total of 896 procedures from 611 patients were included, with 203 (22.7%) procedures in the CI group. Compared to CU procedures, CI procedures had higher rates of moderate-deep sedation during anesthesia recovery (52 [25.6%] vs. 103 [14.9%]; odds ratio [OR], 1.91; 95% CI, 1.30-2.80; P  < 0.01), postoperative pulmonary complications (22 [10.8%] vs. 34 [4.9%]; OR, 2.36[1.22-4.54]; P  =  0.01), and postoperative delirium (32 [16.2%] vs. 24 [3.5%]; OR, 5.33 [2.88-9.86]; P  <  0.01). When moderate-deep sedation during anesthesia recovery was a covariate, both CI (OR, 3.02[1.60-5.70]; P  <  0.01) and moderate-deep sedation (OR, 3.94[2.19-7.11]; P  <  0.01) were associated with delirium. In multivariable analysis, postoperative pulmonary complications were associated with moderate-deep sedation (OR, 2.14[1.18-3.87]; P  = 0 .01) but not with CI (OR, 1.49 [0.76-2.92]; P  = 0 .25).

CONCLUSIONS

Cognitive impairment was associated with higher rates of moderate-deep residual sedation during anesthesia recovery and delirium, while moderate-deep sedation was associated with higher rates of pulmonary complications and delirium. We speculate that tailoring the anesthetic to facilitate faster emergence for CI patients could improve complication rates.

Effects of Acetaminophen, NSAIDs, Gabapentinoids, and Their Combinations on Postoperative Pulmonary Complications After Total Hip or Knee Arthroplasty

Objective

Multimodal analgesia has gained popularity in total hip arthroplasty (THA) and total knee arthroplasty (TKA), but large multicenter studies evaluating specific analgesic combinations are lacking.

Design

A retrospective study using the Premier Healthcare Database (2009–2014).

Subjects

Adults who underwent elective primary THA or TKA.

Methods

We categorized day-of-surgery analgesic exposure using eight mutually exclusive categories: acetaminophen (Ac), nonsteroidal anti-inflammatory drugs (Ns), gabapentinoids (Ga; gabapentin or pregabalin), Ac+Ns, Ac+Ga, Ns+Ga, Ac+Ns+Ga, and none of the three drugs. Multilevel models measured associations of the analgesic categories with a composite of postoperative pulmonary complications (PPCs).

Results

Among 863,139 patients, 75.2% received at least one of the three drugs. In multilevel models, compared with none of the three drugs, Ga use was associated with increased odds of PPCs when used alone (adjusted odds ratio [aOR] = 1.35, 95% confidence interval [CI] = 1.27 to 1.44), combined with Ac (aOR = 1.16, 95% CI = 1.08 to 1.26), or combined with Ns (aOR = 1.28, 95% CI = 1.21 to 1.34). In contrast, the Ac+Ns pair was associated with decreased odds of PPCs (OR = 0.86, 95% CI = 0.83 to 0.90) and lower opioid consumption. Ac+Ns+Ga was not associated with PPCs, whereas it was associated with the lowest opioid consumption on the day of surgery.

Conclusions

Gabapentinoids, alone and in single combination with either acetaminophen or nonsteroidal anti-inflammatory drugs, were associated with higher PPCs, whereas the Ac+Ns pair was associated with fewer PPCs and an opioid-sparing effect. Ac+Ns+Ga was not associated with PPCs, whereas it was associated with the lowest opioid consumption on the day of surgery.

Postoperative nausea and vomiting after bariatric surgery and dexmedetomidine anesthetic: a propensity-weighted analysis

BACKGROUND

Patients undergoing laparoscopic bariatric surgery have high rates of postoperative nausea and vomiting (PONV). Dexmedetomidine based anesthetic could reduce PONV rates.

OBJECTIVES

To determine if PONV rates differ in patients undergoing laparoscopic bariatric surgery with anesthesia primarily based on dexmedetomidine or standard anesthetic management with inhalational agents and opioids.

SETTING

University hospital.

METHODS

From January 2014 to April 2018, 487 patients underwent laparoscopic bariatric surgery and met inclusion criteria (dexmedetomidine, n = 174 and standard anesthetic, n = 313 patients). In both groups, patients received preoperative PONV prophylaxis. We analyzed rates of PONV and moderate-to-deep sedation. A propensity score was calculated and outcomes were assessed using generalized estimating equations with inverse probability of treatment weighting.

RESULTS

Perioperative opioids and volatile anesthetics were reduced in dexmedetomidine patients. During anesthesia recovery the incidence of PONV was similar between dexmedetomidine and standard anesthetic patients (n = 37 [21.3%] versus n = 61 [19.5%], respectively; inverse probability of treatment weighting odds ratio = 1.35; 95% confidence interval .78-2.32, P = .281), and the incidence of sedation higher in dexmedetomidine patients (n = 86 [49.4%] versus n = 75 [24.0%]; inverse probability of treatment weighting odds ratio = 2.43; 95% confidence interval 1.47-4.03, P < 0.001). Rates of PONV and sedation were similar during the remainder of the hospital stay. A secondary sensitivity analysis was performed limited to dexmedetomidine patients who did not receive volatile and results were similar.

CONCLUSIONS

While dexmedetomidine-based anesthesia was associated with reduced opioid and volatile agents use, it was not associated with a reduction of PONV. The higher rates of moderate-to-deep sedation during anesthesia recovery observed with dexmedetomidine may be undesirable in morbidly obese patients.

Dose-Dependent Association of Gabapentinoids with Pulmonary Complications After Total Hip and Knee Arthroplasties

BACKGROUND

Gabapentinoids are commonly prescribed in perioperative multimodal analgesia protocols. Despite widespread use, the optimal dose to reduce opioid consumption while minimizing risks is unknown. We assessed dose-dependent effects of gabapentinoids on opioid consumption and postoperative pulmonary complications following total hip or knee arthroplasty (THA or TKA). We hypothesized that use of a gabapentinoid on the day of THA or TKA is associated with an increased risk of postoperative pulmonary complications in a dose-response fashion compared with the risk for patients who did not receive the drug.

METHODS

Using the Premier Database, we identified adults who underwent elective primary THA or TKA from 2009 to 2014. The exposure was receipt of a gabapentinoid (gabapentin or pregabalin) on the day of surgery. Gabapentin dose was categorized into 5 groups: none, 1 to 350, 351 to 700, 701 to 1,050, and >1,050 mg per day. Pregabalin dose was categorized into 4 groups: none, 1 to 110, 111 to 250, and >250 mg per day. The primary outcome was a composite of postoperative pulmonary complications, defined as respiratory failure, pneumonia, reintubation, pulmonary edema, noninvasive ventilation, or invasive mechanical ventilation.

RESULTS

Of 858,306 patients who underwent THA or TKA, 11.0% received gabapentin and 10.2% received pregabalin. The mean age (and standard deviation) of the patients was 65.6 ± 10.7 years, 39.6% were male, 78.2% were Caucasian, and 55.2% were covered by Medicare. In multilevel regression analysis, receipt of gabapentinoid at any dose on the day of surgery was associated with increased odds of postoperative pulmonary complications. Compared with no exposure to the drug being used by the particular group, all dose ranges of gabapentin and pregabalin were associated with greater odds of postoperative pulmonary complications (odds ratio, 95% confidence interval = 1.51, 1.40 to 1.63, for >1,050 mg of gabapentin and 1.81, 1.57 to 2.09, for >250 mg of pregabalin). We found no clinically meaningful associations between exposure to either gabapentin or pregabalin and perioperative opioid consumption or the length of the hospital stay.

CONCLUSIONS

Exposure to gabapentinoids at any dose on the day of THA or TKA was associated with increased odds of postoperative pulmonary complications in a dose-response fashion, with minimal effects on perioperative opioid consumption.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Postoperative pulmonary complications in contemporary cohort of patients with pulmonary hypertension

Patients with pulmonary hypertension are at increased risk for postoperative pulmonary complications (PPCs). Herein, we review PPCs in pulmonary hypertension patients undergoing non-cardiac procedures under general anesthesia. The medical records of pulmonary hypertension patients who underwent surgery with general anesthesia between 2010 and 2017 were reviewed for PPCs. In addition we reviewed nursing-documented respiratory depressive episodes in the post-anesthesia care unit to assess the associations between these episodes and later PPCs. There were 20 PPCs among 128 patients who underwent 197 procedures (10.2 per 100 surgeries) [95% CI 6.7-15.2]. Of these, 5 occurred during anesthesia recovery and 15 following anesthesia recovery. Three-quarters of the PPCs occurred within 24 postoperative hours. All the PPCs were severe. The frequency of PPCs was significantly higher in those who experienced respiratory depression during anesthesia recovery vs. in those who did not (5/17, 29% vs. 10/175, 6%; odds ratio 5.15, 95% CI 1.58-16.81, p = 0.007). Increased PPC rates were observed among patients who were current/previous smokers and who routinely use benzodiazepines, and among those undergoing emergent surgery. With treatment, all PPCs resolved. The rate of PPCs in the population of contemporary surgical pulmonary hypertension patients was 10.2%, and three-quarters occurred during first 24 postoperative hours. Patients who had respiratory depression during anesthesia recovery were 5-fold more likely to experience later PPCs.

Effect of Perioperative Gabapentin on Postoperative Pain Resolution and Opioid Cessation in a Mixed Surgical Cohort: A Randomized Clinical Trial

Importance

Guidelines recommend using gabapentin to decrease postoperative pain and opioid use, but significant variation exists in clinical practice.

Objective

To determine the effect of perioperative gabapentin on remote postoperative time to pain resolution and opioid cessation.

Design, Setting, and Participants

A randomized, double-blind, placebo-controlled trial of perioperative gabapentin was conducted at a single-center, tertiary referral teaching hospital. A total of 1805 patients aged 18 to 75 years scheduled for surgery (thoracotomy, video-assisted thoracoscopic surgery, total hip replacement, total knee replacement, mastectomy, breast lumpectomy, hand surgery, carpal tunnel surgery, knee arthroscopy, shoulder arthroplasty, and shoulder arthroscopy) were screened. Participants were enrolled from May 25, 2010, to July 25, 2014, and followed up for 2 years postoperatively. Intention-to-treat analysis was used in evaluation of the findings.

Interventions

Gabapentin, 1200 mg, preoperatively and 600 mg, 3 times a day postoperatively or active placebo (lorazepam, 0.5 mg) preoperatively followed by inactive placebo postoperatively for 72 hours.

Main Outcomes and Measures

Primary outcome was time to pain resolution (5 consecutive reports of 0 of 10 possible levels of average pain at the surgical site on the numeric rating scale of pain). Secondary outcomes were time to opioid cessation (5 consecutive reports of no opioid use) and the proportion of participants with continued pain or opioid use at 6 months and 1 year.

Results

Of 1805 patients screened for enrollment, 1383 were excluded, including 926 who did not meet inclusion criteria and 273 who declined to participate. Overall, 8% of patients randomized were lost to follow-up. A total of 202 patients were randomized to active placebo and 208 patients were randomized to gabapentin in the intention-to-treat analysis (mean [SD] age, 56.7 [11.7] years; 256 (62.4%) women and 154 (37.6%) men). Baseline characteristics of the groups were similar. Perioperative gabapentin did not affect time to pain cessation (hazard ratio [HR], 1.04; 95% CI, 0.82-1.33; P = .73) in the intention-to-treat analysis. However, participants receiving gabapentin had a 24% increase in the rate of opioid cessation after surgery (HR, 1.24; 95% CI, 1.00-1.54; P = .05). No significant differences were noted in the number of adverse events as well as the rate of medication discontinuation due to sedation or dizziness (placebo, 42 of 202 [20.8%]; gabapentin, 52 of 208 [25.0%]).

Conclusions and Relevance

Perioperative administration of gabapentin had no effect on postoperative pain resolution, but it had a modest effect on promoting opioid cessation after surgery. The routine use of perioperative gabapentin may be warranted to promote opioid cessation and prevent chronic opioid use. Optimal dosing and timing of perioperative gabapentin in the context of specific operations to decrease opioid use should be addressed in further research.

Trial Registration

clinicaltrials.gov Identifier: NCT01067144.

Acute Pain in Older Adults: Recommendations for Assessment and Treatment

The management of acute pain in older adults (age 65 or greater) requires special attention due to various physiologic, cognitive, functional, and social issues that may change with aging. Especially in the postoperative setting, there are significant complications that can occur if pain is not treated adequately for elderly patients. In this article, the authors describe these changes in detail and discuss how pain should be assessed appropriately in older patients. In addition, the authors detail the unique risks and benefits of several mainstream analgesic medications as well as interventional treatments for elderly patients. The authors' goal is to provide recommendations for health care providers on appropriately recognizing and treating pain in a safe, effective manner for aging patients.

Effects of Sugammadex on Time of First Postoperative Bowel Movement: A Retrospective Analysis

Objective

To determine whether time to first postoperative bowel movement after intraperitoneal surgery differs among neuromuscular blockade reversal with either anticholinesterase/anticholinergic combination vs sugammadex.

Patients and Methods

Sugammadex was introduced to our practice in October 2016. Patients were identified who underwent intraperitoneal surgery between January 1, through June 30, 2016, and January 1 through June 30, 2017, and received aminosteroid neuromuscular blockade for paralysis. Reversal was initiated with neostigmine, coadministered with glycopyrrolate (neostigmine/glycopyrrolate) for control participants and sugammadex for patients. Time to first bowel movement was determined from nursing documentation for study cohorts (2016 and 2017). We compared times to first bowel movement between cases and controls using raw and inverse probability of treatment weighting (IPTW) analyses.

Results

In the 2016 cohort, 2583 received neostigmine/glycopyrrolate. Of 2750 patients in 2017, sugammadex reversal technique was administered to 1500 patients and neostigmine/glycopyrrolate to 1250 participants. Without weighting, the groups were relatively balanced for most baseline characteristics, and after IPTW, all standardized differences were <0.035. In comparison with the 2016 and 2017 controls, sugammadex treatment was associated with faster occurrence of first bowel movement. For 2016, unweighted hazard ratio (HR) (95% confidence interval [CI]) was 1.35 (1.21-1.51) (P<.001). After IPTW, HR (95% CI) was 1.27 (1.12-1.43) (P<.001). For 2017, unweighted HR (95% CI) was 1.51 (1.31-1.72) (P<.001); after IPTW, it was 1.25 (1.08-1.45) (P =.003).

Conclusion

Patients undergoing intraperitoneal surgery who had aminosteroid neuromuscular blockade reversal with sugammadex had earlier first postoperative bowel movement than patients with reversal through neostigmine/glycopyrrolate.

Characterization of respiratory compromise and the potential clinical utility of capnography in the post-anesthesia care unit: a blinded observational trial

The utility of capnography to detect early respiratory compromise in surgical patients after anesthesia is unclear due to limited prospective data. The purpose of this trial was to determine the frequency and duration of capnography-detected respiratory adverse events in the post-anesthesia care unit (PACU). In this prospective observational trial, 250 consenting patients undergoing elective surgery with general anesthesia were monitored by standard monitoring together with blinded capnography and pulse oximetry monitoring. The capnography notification settings were adjusted to match nursing (Level II) and physician (Level I) alarm thresholds. 163 (95%) patients had a Level II notification and 135 (78%) had a Level I notification during standard monitoring. The most common events detected by the capnography monitor included hypocapnia, apnea, tachypnea, bradypnea and hypoxemia, with silent notification duration for these events ranging from 17 ± 13 to 189 ± 127 s. During standard monitoring, 15 respiratory adverse events were reported, with 8 events occurring when valid blinded/silenced capnography and pulse oximetry data was collected simultaneously. Capnography and the Integrated Pulmonary Index™ algorithm (IPI) detected respiratory adverse events earlier than standard monitoring in 75% and 88% of cases, respectively, with an average early warning time of 8 ± 11 min. Three patients’ blinded capnography was unblinded to facilitate clinical care. Respiratory adverse events are frequent in the PACU, and the addition of capnography and IPI to current standard monitoring provides potentially clinically relevant information on respiratory status, including early warning of some respiratory adverse events.

Trial registration ClinialTrials.gov Identifier NCT02707003 (https://clinicaltrials.gov/ct2/show/NCT02707003).

Respiratory Depression Following Ambulatory Urogynecologic Procedures

Objective

To assess the rate of postanesthesia respiratory depression (RD) and test for potential associations with clinical characteristics of patients undergoing urogynecologic procedures at ambulatory surgical centers (ASCs). Postanesthesia RD is poorly characterized for patients undergoing urogynecologic procedures in ASCs.

Patients and Methods

Health records of adult patients undergoing urogynecologic procedures at an ASC from July 1, 2010, through December 31, 2015, were abstracted. Cases complicated by RD were identified, and analyses of risk factors were performed with generalized estimating equations (GEE).

Results

During the study time frame, 9105 patients underwent 9141 procedures, of which RD complicated 221 cases (mean [95% confidence interval (CI)] complication rate per 100 cases, 2.4 [2.1-2.8]). Risk increased with advancing age, male sex, obstructive sleep apnea (OSA), morbid obesity, and use of volatile anesthetics and airway secured. Patients with RD had longer anesthesia recovery (median [interquartile range], 135 [110-166] vs 105 [80-138] minutes; P<.001). Within 48 postprocedural hours, 290 ED visits or hospitalizations occurred, but this risk was not increased by RD (adjusted odds ratio [95% CI], 0.62 [0.30-1.26]; P=.12).

Conclusion

Postanesthesia RD after ambulatory urogynecologic procedures delay anesthesia recovery but are not associated with later complications. Patients with OSA or having other conditions related to OSA, or both, are at higher risk for RD.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

Gabapentin increases expression of δ subunit-containing GABAA receptors

BACKGROUND

Gabapentin is a structural analog of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Its anticonvulsant, analgesic and anxiolytic properties suggest that it increases GABAergic inhibition; however, the molecular basis for these effects is unknown as gabapentin does not directly modify GABA type A (GABA_A) receptor function, nor does it modify synaptic inhibition. Here, we postulated that gabapentin increases expression of δ subunit-containing GABA_A (δGABA_A) receptors that generate a tonic inhibitory conductance in multiple brain regions including the cerebellum and hippocampus.

METHODS

Cell-surface biotinylation, Western blotting, electrophysiologic recordings, behavioral assays, high-performance liquid chromatography and gas chromatography-mass spectrometry studies were performed using mouse models.

FINDINGS

Gabapentin enhanced expression of δGABA_A receptors and increased a tonic inhibitory conductance in neurons. This increased expression likely contributes to GABAergic effects as gabapentin caused ataxia and anxiolysis in wild-type mice but not δ subunit null-mutant mice. In contrast, the antinociceptive properties of gabapentin were observed in both genotypes. Levels of GABA_A receptor agonists and neurosteroids in the brain were not altered by gabapentin.

INTERPRETATION

These results provide compelling evidence to account for the GABAergic properties of gabapentin. Since reduced expression of δGABA_A receptor occurs in several disorders, gabapentin may have much broader therapeutic applications than is currently recognized. FUND: Supported by a Foundation Grant (FDN-154312) from the Canadian Institutes of Health Research (to B.A.O.); a NSERC Discovery Grant (RGPIN-2016-05538), a Canada Research Chair in Sensory Plasticity and Reconsolidation, and funding from the University of Toronto Centre for the Study of Pain (to R.P.B.).

Pain Management in Enhanced Recovery after Surgery (ERAS) Protocols

Pain control is an integral part of Enhanced Recovery after Surgery (ERAS) protocols for colorectal surgery. While opioid therapy remains the mainstay of therapy for postsurgical pain, opioids have undesired side effects including delayed recovery of bowel function, respiratory depression, and postoperative nausea and vomiting. A variety of nonopioid systemic medical therapies as well as regional and neuraxial techniques have been described as improving pain control while reducing opioid use. Multimodal and preemptive analgesia as part of an ERAS protocol facilitates early mobility and early return of bowel function and decreases postoperative morbidity. In this review, we examine several multimodal therapies and their impact on postoperative analgesia, opioid use, and recovery for patients undergoing colorectal surgery.