Intraoperative Use of Remifentanil for TIVA: Postoperative Pain, Acute Tolerance, and Opioid-Induced Hyperalgesia

Remifentanil-induced hyperalgesia: the current state of affairs

Remifentanil-induced hyperalgesia (RIH) is a part of a general opioid-induced hyperalgesia (OIH) syndrome, seemingly resulting from abrupt cessation of continuous remifentanil infusion at rates equal or exceeding 0.3 mcg/kg/min. The intricate mechanisms of its development are still not completely understood. However, hyperactivation of the N -methyl d -aspartate receptor system, descending spinal facilitation and increased concentration of dynorphin (a κ-opioid ligand) are commonly proposed as possible mechanisms. Several ways of prevention and management have been suggested, such as slow withdrawal of remifentanil infusion, the addition of propofol, pretreatment with or concomitant administration of ketamine, buprenorphine, cyclooxygenase-2 inhibitors (NSAIDs), methadone, dexmedetomidine. In clinical and animal studies, these strategies exhibited varying success, and many are still being investigated.

The effect of pre-emptive oral pregabalin on opioid consumption in patients undergoing laparoscopic sleeve gastrectomy with an analysis of intraoperative hemodynamic stability and quality of recovery: study protocol for a randomized, prospective, double-blind study

BACKGROUND

Obese patients undergoing laparoscopic sleeve gastrectomy (LSG) are particularly at risk of opioid-related side effects. To reduce patient exposure to opioids, multimodal analgesia, which involves the use of drugs of different classes, may be utilized. One of the drugs under consideration is pregabalin. Despite an opioid-sparing potential, few studies assess the role of pregabalin as an element of multimodal analgesia in LSG. Considering the limited number and inconsistent results of available studies, we decided to conduct a randomized, prospective study on the effect of preemptive pregabalin administration in obese patients on opioid consumption, pain scores, the incidence of opioid side effects, and hemodynamical stability.

METHODS

The study is designed as a prospective randomized controlled trial with double-blinding. Randomization will be performed in a block with a parallel 1:1 allocation. The intervention will involve receiving a pregabalin 150 mg capsule 1-2 h before the surgery, whereas the control group will receive an identically looking placebo. The primary outcome measure will be total oxycodone consumption in the first 24 h following surgery. Secondary outcome measures will be pain severity assessed using the Numerical Rating Scale (NRS) 1, 6, 12, and 24 h after surgery, postoperative sedation on the Ramsay scale, PONV impact scale, the incidence of desaturation episodes < 94%, and episodes of blurred vision at 1, 6, 12, and 24 h after surgery, intraoperative hemodynamic parameters such as heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), total fluid volume, and total ephedrine dose. Patient comfort will be additionally assessed using the QoR-40 questionnaire at discharge.

DISCUSSION

The study will explore the efficacy and safety of preemptive pregabalin in a dose of 150 mg as a co-analgesic used in multimodal analgesia for LSG. As studies on opioid-sparing regimes concern the safety of obese patients, we aim to contribute objective data with a relatively large study sample size. The result of the present clinical trial may support the reassessment of recommendations to use pregabalin in the studied population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05804591. Registered on 07.04.2023.

Remifentanil-induced hyperalgesia in healthy volunteers: a systematic review and meta-analysis of randomized controlled trials

ABSTRACT

Recent literature suggests that the withdrawal of remifentanil (RF) infusion can be associated with hyperalgesia in clinical and nonclinical settings. We performed a systematic review and a meta-analysis of randomized controlled trials with cross-over design, to assess the effect of discontinuing RF infusion on pain intensity and areas of hyperalgesia and allodynia in healthy volunteers. Nine studies were included. The intervention treatment consisted in RF infusion that was compared with placebo (saline solution). The primary outcome was pain intensity assessment at 30 ± 15 minutes after RF or placebo discontinuation, assessed by any pain scale and using any quantitative sensory testing. Moreover, postwithdrawal pain scores were compared with baseline scores in each treatment. Secondary outcomes included the areas (% of basal values) of hyperalgesia and allodynia. Subjects during RF treatment reported higher pain scores after discontinuation than during treatment with placebo [standardized mean difference (SMD): 0.50, 95% confidence interval (CI): 0.03-0.97; P = 0.04, I 2 = 71%]. A significant decrease in pain scores, compared with baseline values, was found in the placebo treatment (SMD: -0.87, 95% CI: -1.61 to -0.13; P = 0.02, I 2 = 87%), but not in the RF treatment (SMD: -0.28, 95% CI: -1.18 to 0.62; P = 0.54, I 2 = 91%). The area of hyperalgesia was larger after RF withdrawal (SMD: 0.55; 95% CI: 0.27-0.84; P = 0.001; I 2 = 0%). The area of allodynia did not vary between treatments. These findings suggest that the withdrawal of RF induces a mild but nonclinically relevant degree of hyperalgesia in HVs, likely linked to a reduced pain threshold.

Error traps and preventative strategies for adolescent idiopathic scoliosis spinal surgery

Anesthesia for posterior spinal fusion for adolescent idiopathic scoliosis remains one of the most common surgeries performed in adolescents. These procedures have the potential for significant intraprocedural and postoperative complications. The potential for pressure injuries related to prone positioning must be understood and addressed. Additionally, neuromonitoring remains a mainstay for patient care in order to adequately assess patient neurologic integrity and alert the providers to a reversible action. As such, causes of neuromonitoring signal loss must be well understood, and the provider should have a systematic approach to signal loss. Further, anesthetic design must facilitate intraoperative wake-up to allow for a definitive assessment of neurologic function. Perioperative bleeding risk is high in posterior spinal fusion due to the extensive surgical exposure and potentially lengthy operative time, so the provider should undertake strategies to reduce blood loss and avoid coagulopathy. Pain management for adolescents undergoing spinal fusion is also challenging, and inadequate analgesia can delay recovery, impede patient/family satisfaction, increase the risk of chronic postsurgical pain/disability, and lead to prolonged opioid use. Many of the significant complications associated with this procedure, however, can be avoided with intentional and evidence-based approaches covered in this review.

Can Electroacupuncture Be Useful in Opioid-Induced Hyperalgesia? A Case Report

Opioid-induced hyperalgesia (OIH) is characterized by a paradoxical increase in pain sensitivity following opioid exposure. Although animal models indicate that electroacupuncture (EA) is effective against pain sensitization, there are no reports of its clinical application in OIH treatment. This case report involves an adult patient with osteomalacia complicated by multiple vertebral fragility fractures. The patient developed OIH following the use of oxycodone to treat severe disabling lower back pain that was refractory to nonsteroidal anti-inflammatory drugs. After hospitalization and treatment with low EA-frequency (2-10 Hz) sessions, the patient exhibited significant pain reduction and functional recovery after the first session, which was accompanied by steady progressive improvement as the treatment continued. This case report illustrates the clinical efficacy of EA in OIH treatment and indicates that EA, which has multiple modes of action on the neurobiology of chronic pain, has potential applications in the management of complex and difficult-to-manage conditions, such as OIH.

Effect of peripheral nerve block versus general anesthesia on the hemodynamics and prognosis of diabetic patients undergoing diabetic foot Surgery

BACKGROUND

Diabetic foot ulcers (DFUs) represent a significant foot-related concern for patients with multiple co-morbidities, and surgical intervention is often employed. Notably, peripheral nerve block anesthesia (PNB) has emerged as a new approach for the surgical management of DFUs, providing sustained hemodynamic stability and superior postoperative pain control compared to general anesthesia (GEA).

METHODS

The present study utilized a retrospective analysis of hospitalized patients who met the inclusion criteria for DFUs over a period of 7 years. Patients were categorized into two groups based on the type of anesthesia employed during the procedure: GEA or PNB. Extensive patient information was gathered and analyzed, such as demographics, intraoperative hemodynamic parameters, numeric rating scale (NRS) scores, and healing outcomes. The preliminary results assessed in this study were intraoperative hemodynamic stability and postoperative analgesic efficacy.

RESULTS

During the study period, 117 patients received surgical therapy based on GEA, while 145 patients received PNB. Notably, the mean intraoperative blood pressure was significantly lower in the GEA group, and this difference remained statistically significant even after Bonferroni adjustment using linear mixed models. Additionally, the frequency of hypotensive episodes was higher in the GEA group (P < 0.05). Furthermore, the perioperative transfusion volume, overall intraoperative fluid input, and intraoperative bleeding volume were significantly more significant in the GEA group than in the PNB group. The postoperative pain NRS scores differed considerably between the two groups (Bonferroni corrected P < 0.01), with the GEA group exhibiting higher opioid consumption on the day of surgery and the first postoperative day when using patient-controlled intravenous analgesia (PCIA). Supplemental analgesic medication was more significant in the GEA group 24 h postoperatively. However, the two groups had no difference in hospital stay or treatment outcomes. There was no difference between the two groups regarding secondary surgery and amputation procedures. Although the 5-year mortality rate is 30.5%, no significant difference in mortality rates between the two groups was observed.

CONCLUSIONS

Compared to GEA, PNB is a safe and effective alternative therapy for managing DFUs. Our findings suggest that PNB administration during surgical intervention for this condition results in more stable intraoperative hemodynamics and superior postoperative analgesic effects, despite no significant difference in overall treatment outcomes between the two groups. The two groups did not differ in re-surgery, amputation, or 5-year mortality.

Perioperative analgesia in the elderly

The administration of analgesic drugs in elderly patients should take into account age-related physiological changes, loss of efficiency of homeostatic mechanisms, and pharmacological interactions with chronic therapies. Underestimation of pain in patients with impaired cognition is often linked to difficulties in pain assessment. In the preoperative phase, it is essential to assess the physical status, cognitive reserve, and previous chronic pain conditions to plan effective analgesia. Furthermore, an accurate pharmacological history of the patient must be collected to establish any possible interaction with the whole perioperative analgesic plan. The use of analgesic drugs with different mechanisms of action for pain relief in the intraoperative phase is a crucial step to achieve adequate postoperative pain control in older adults. The combined multimodal and opioid-sparing strategy is strongly recommended to reduce side effects. The use of various adjuvants is also preferable. Moreover, the implementation of non-pharmacological approaches may lead to faster recovery. High-quality postoperative analgesia in older patients can be achieved only with a collaborative interdisciplinary team. The aim of this review is to highlight the perioperative pain management strategies in the elderly with a special focus on intraoperative pharmacological interventions.

Paralysis Versus Non-Paralysis Anesthesia for Operative Laryngoscopy: A Randomized Controlled Trial

OBJECTIVE

To compare outcomes between two standard-of-care anesthesia regimens for operative laryngoscopy: general anesthesia with a neuromuscular blocking agent (NMBA) versus remifentanil and propofol (non-NMBA).

METHODS

This was a prospective, single-blinded, randomized controlled trial at a tertiary care center. Patients were randomized to either anesthesia using rocuronium (NMBA) or with remifentanil/propofol infusion alone (non-NMBA). Intraoperative impressions, anesthesia data, and post-operative patient surveys were collected.

RESULTS

Sixty-one patients who underwent suspension laryngoscopy from 2020 to 2022 were included (25 female, 36 male, ranging 20-81 years). Thirty patients were enrolled in the NMBA arm and 31 patients in the non-NMBA arm. Heart rate and mean arterial pressure were higher in the NMBA (p < 0.01). Patients in the non-NMBA group were more likely to require vasopressors (p = 0.04, RR = 3.08 [0.86-11.05]). Surgeons were more frequently satisfied with conditions in the NMBA group (86.7%) compared to the non-NMBA group (58.1%, p < 0.01). Procedures were more likely to be paused due to movement in the non-NMBA group (45.1%) compared to the NMBA group (16.6%, p < 0.03, RR = 2.26 [1.02-4.99]). Patients in the non-NMBA group were more likely to endorse myalgia the week after surgery (44%) compared to the NMBA group (8.3%, p < 0.01) and reported higher average pain levels on a 0-10 pain scale (3.7) compared to the paralysis group (2.0).

CONCLUSIONS

Anesthesia with rocuronium was associated with better intraoperative conditions and postoperative pain compared to anesthesia with remifentanil/propofol. Remifentanil/propofol were associated with lower blood pressure and suppression of laryngoscopy-associated tachycardia.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:2654-2664, 2023.

Efficacy and safety of flurbiprofen‑axetil combined with nalbuphine pretreatment on remifentanil‑induced postoperative hyperalgesia: A randomized clinical trial

Remifentanil-induced hyperalgesia (RIH) is a common and complicated issue in patients undergoing laparoscopic cholecystectomy (LC), which significantly reduces patient satisfaction. The present trial was designed to clarify the individual and combined effects of flurbiprofen-axetil and nalbuphine on remifentanil-induced hyperalgesia. This randomized double-blind clinical trial included 120 adult patients who underwent LC at The Second People's Hospital of Wuhu. The individuals were randomized into a flurbiprofen-axetil group (F group), nalbuphine group (N group), flurbiprofen-axetil combined with nalbuphine group (FN group) and saline group (S group). The four groups were given flurbiprofen-axetil (50 mg, iv.), nalbuphine (0.1 mg/kg, iv.), flurbiprofen-axetil (50 mg, iv.) combined with nalbuphine (0.1 mg/kg, iv.) or normal saline respectively prior to skin incision. The primary outcome was the postoperative mechanical pain thresholds at the inner forearm and peri-incisional area. The secondary outcomes were the visual analog scale (VAS) and Ramsay sedation scale at 0.5, 1, 4 and 24 h after surgery, and any other adverse events. The pain threshold of the medial forearm in the FN group did not differ from that in the F and N groups at 24 h after surgery (P=0.310 and P=0.910, respectively). However, the pain threshold around the incision in FN group was significantly lower than that in F and N groups 24 h after surgery (P=0.001). The VAS of the F group, N group and FN group were all significantly lower than that in the S group at 0.5, 1 and 24 h after surgery (P<0.001). No significant differences were observed in the incidence of adverse events between the four groups. Single flurbiprofen-axetil and single nalbuphine effectively prevented RIH 24 h after surgery in LC. The combination of the two analgesic drugs, with different mechanisms of action, was not superior to single therapy. The present study was registered with the Chinese Clinical Trial Registry (registration no. ChiCTR2100045347).

Association between intraoperative remifentanil use and postoperative hyperalgesia in adolescent idiopathic scoliosis surgery: a retrospective study

BACKGROUND

The liberal use of remifentanil in spine surgery has been associated with an increased incidence of postoperative hyperalgesia. Nevertheless, controversies remain as the existing evidence is inconclusive to determine the relationship between remifentanil use and the development of opioid-induced hyperalgesia. We hypothesized that intraoperative infusion of higher dose remifentanil during scoliosis surgery is associated with postoperative hyperalgesia, manifesting clinically as greater postoperative morphine consumption and pain scores.

METHODS

Ninety-seven patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion surgery at a single tertiary institution from March 2019 until June 2020 were enrolled in this retrospective study. Anesthesia was maintained using a target-controlled infusion of remifentanil combined with volatile anesthetic desflurane in 92 patients, while five patients received it as part of total intravenous anesthesia. Intravenous ketamine, paracetamol, and fentanyl were administered as multimodal analgesia. All patients received patient-controlled analgesia (PCA) morphine postoperatively. Pain scores at rest and on movement, assessed using the numerical rating scale, and the cumulative PCA morphine consumption were collected at a six-hourly interval for up to 48 h. According to the median intraoperative remifentanil dose usage of 0.215 µg/kg/min, patients were divided into two groups: low dose and high dose group.

RESULTS

There were no significant differences in the pain score and cumulative PCA morphine consumption between the low and high dose remifentanil group. The mean duration of remifentanil infusion was 134.9 ± 22.0 and 123.4 ± 23.7 min, respectively.

CONCLUSION

Intraoperative use of remifentanil as an adjuvant in AIS patients undergoing posterior spinal fusion surgery was not associated with postoperative hyperalgesia.

Surgeon-Specific Treatment Selection Bias and Heterogeneous Perioperative Practices in an Observational Spine Surgery Study. A Statistical Tutorial with Implications for Analysis of Observational Studies of Perioperative Interventions

BACKGROUND

It is essential that treatment effects reported from retrospective observational studies are as reliable as possible. In a retrospective analysis of spine surgery patients, we obtained a spurious result: tranexamic acid (TXA) had no effect on intraoperative blood loss. This statistical tutorial explains how this result occurred and why statistical analyses of observational studies must consider the effects of individual surgeons.

METHODS

We used an observational database of 580 elective adult spine surgery patients, supplemented with a review of perioperative medication records. We tested whether common statistical methods (multivariable regression or propensity score-based methods) could adjust for surgeons' selection bias in TXA administration.

RESULTS

Because TXA administration (frequency, timing, and dose) and surgeon were linked (collinear), estimating and testing the independent effect of TXA on outcome using multivariable regression without including surgeon as a variable would provide biased (spurious) results. Likewise, because of surgeon/TXA linkage, assumptions of propensity score-based analysis were violated, statistical methods to improve comparability between groups failed, and spurious blood loss results were worsened. Others numerous differences among surgeons existed in intraoperative and postoperative practices and outcomes.

CONCLUSIONS

In observational studies in which individual surgeons determine whether their patients receive the treatment of interest, consideration must be given to inclusion of surgeon as an independent variable in all analyses. Failure to include the surgeon in an analysis of observational data carries a substantial risk of obtaining spurious results, either creating a spurious treatment effect or failing to detect a true treatment effect.

Efficacy of Dexmedetomidine vs. Remifentanil for Postoperative Analgesia and Opioid-Related Side Effects after Gynecological Laparoscopy: A Prospective Randomized Controlled Trial

Remifentanil is widely used for intraoperative analgesia, but often causes remifentanil-induced hyperalgesia (RIH) and related side effects. Dexmedetomidine, a non-opioid analgesic, has been used as an alternative to remifentanil to prevent RIH. We aimed to investigate the effect of dexmedetomidine on postoperative recovery after gynecological laparoscopy. Ninety-six adult patients undergoing elective gynecological laparoscopy were randomly assigned to the dexmedetomidine or remifentanil groups. The primary outcome was the pain score at 30 min after surgery. The secondary outcomes were intraoperative adverse events (hypotension and bradycardia) and postoperative opioid-related side effects (nausea, vomiting, requirement for rescue analgesics, and shivering). We also performed an ancillary cytokine study to evaluate oxidative stress, one of the causes of RIH. Compared with the remifentanil group, the dexmedetomidine group had lower pain scores at 30 min after surgery (4.0 ± 1.9 vs. 6.1 ± 2.0, mean ± SD, p < 0.001) and lower incidence of intraoperative hypotension and postoperative nausea, vomiting, and shivering. Furthermore, the proportion of patients requiring rescue analgesics was significantly lower in the dexmedetomidine than in the remifentanil group (25% vs. 66.7%, p < 0.001). Cytokine levels did not differ between the groups. Dexmedetomidine showed a better analgesic effect with minimal opioid-related side effects and is considered superior to remifentanil for intraoperative analgesia.

Intravenous diclofenac and orphenadrine for the treatment of postoperative pain after remifentanil-based anesthesia : A double-blinded, randomized, placebo-controlled study

BACKGROUND

Postoperative intravenous diclofenac reduces patient opioid demand and is commonly used in surgical units. Orphenadrine is mainly used in combination with diclofenac for musculoskeletal injuries and postoperative pain control. The objective of this study was to compare the analgesic efficacy of diclofenac-orphenadrine, diclofenac alone and saline.

METHODS

We performed a double-blind, randomized, placebo-controlled, parallel-group, single-center clinical study investigating the opioid-sparing effect of a combination of diclofenac and orphenadrine versus diclofenac alone versus isotonic saline solution. Initially 72 patients were included and received total intravenous anesthesia during cruciate ligament surgery. All patients were postoperatively treated with a patient-controlled analgesia (PCA) device containing hydromorphone. Pharmacological safety was assessed by laboratory parameters, vital signs, and delirium detection scores.

RESULTS

There was no significant difference between the groups in cumulative dose of PCA analgesics required after 24 h postsurgery, with 5.90 mg (SD ± 2.90 mg) in the placebo group, 5.73 mg (SD ± 4.75 mg) in the diclofenac group, and 4.13 mg (SD ± 2.57 mg) in the diclofenac-orphenadrine group. Furthermore, there was no significant difference between the groups in cumulative dose of PCA analgesics required 2 h postsurgery (n = 65). Mean dose of hydromorphone required after 2 h was 1.54 mg (SD ± 0.57 mg) in the placebo group, 1.56 mg (SD ± 1.19 mg) in the diclofenac-only group, and 1.37 mg (SD ± 0.78 mg) in the diclofenac-orphenadrine group. However, when comparing the diclofenac-orphenadrine group and the diclofenac group combined to placebo there was a significant reduction in PCA usage in the first 24 h postsurgery. In total, there were 25 adverse events reported, none of which were rated as severe.

CONCLUSION

Orphenadrine-diclofenac failed to significantly reduce postoperative opioid requirements. However, in an exploratory post hoc analysis the diclofenac-orphenadrine and the diclofenac group combined versus placebo showed a tendency to reduce opioid demand in postoperative pain control. Further research is required to determine the value of orphenadrine as an adjuvant in a multimodal approach for postoperative pain management.

Usefulness of Analgesia Nociception Index for guiding intraoperative opioid administration: a systematic review and meta-analysis

INTRODUCTION

This study primarily aimed at investigating the efficacy of Analgesia Nociception Index (ANI) for guiding intraoperative opioid administration in patients receiving surgery under general anesthesia.

EVIDENCE ACQUISITION

The Medline, Embase, Google scholar, and the Cochrane Library databases were searched from inception to April 2022 for randomized controlled trials. The primary outcome was intraoperative opioid administration, while the secondary outcomes included postoperative opioid consumption, pain score, emergency time, risk of nausea/vomiting (PONV), and Postanesthesia Care Unit (PACU) stay.

EVIDENCE SYNTHESIS

Six studies including 399 participants (published from 2015 to 2022) focused on non-cardiac surgery, including spine surgery (two trials), breast surgery (two trials), gynecologic surgery (one trial), and laparoscopic cholecystectomy (one trial) were included. Meta-analysis revealed no difference in intraoperative opioid administration with the use of ANI-guided analgesia compared to the control group that used conventional clinical measurements (e.g., heart rate) to guide opioid use [standardized mean difference (SMD)=-0.17, 95% CI: -0.56 to 0.22, P=0.39, I²=72%, six trials, 399 participants]. Gender-based subgroup analysis showed effectiveness of ANI for reducing opioid administration in female patients (SMD=-0.53, P=0.02). There were no differences in postoperative recovery characteristics including pain score [Mean difference (MD): -0.03, P=0.79], opioid consumption (SMD: -0.34, P=0.08), emergence time (MD=1.12, P=0.47), length of stay in the PACU (MD: -0.56, P=0.83), and risk of PONV [risk ratio(RR): 0.75, P=0.46] between the two groups.

CONCLUSIONS

Analgesia nociception index-guided analgesia was unable to reduce intraoperative opioid administration compared to monitoring using conventional clinical parameters. Further studies are required to support our findings.

Effect of remifentanil on post-operative analgesic consumption in patients undergoing shoulder arthroplasty after interscalene brachial plexus block: a randomized controlled trial

PURPOSE

Remifentanil is useful in balanced anesthesia; however, there is concern regarding opioid-induced hyperalgesia. The effect of remifentanil on rebound pain, characterized by hyperalgesia after peripheral nerve block has rarely been studied. This study evaluated whether intraoperative remifentanil infusion may increase postoperative analgesic requirement in patients receiving preoperative interscalene brachial plexus block (IBP).

METHODS

Sixty-eight patients undergoing arthroscopic shoulder surgery under general anesthesia were randomly allocated to remifentanil (R) or control (C) group. Preoperative IBP with 0.5% ropivacaine 15 mL was performed in all patients. Intraoperative remifentanil was administered only in the R group. Postoperative pain was controlled using intravenous patient-controlled analgesia (IV-PCA) and rescue analgesics. The primary outcome was the dosage of fentanyl-nefopam IV-PCA infused over 24 h postoperatively. The secondary outcomes included the numeric rating scale (NRS) score recorded at 4-h intervals over 24 h, amount of rescue analgesics and total postoperative analgesics used over 24 h, occurrence of intraoperative hypotension, postoperative nausea and vomiting (PONV) and delirium.

RESULTS

The dosage of fentanyl-nefopam IV-PCA was significantly less in C group than R group for postoperative 24 h. Fentanyl 101 [63-158] (median [interquartile range]) µg was used in the C group, while fentanyl 161 [103-285] µg was used in the R group (median difference 64 µg, 95% CI 10-121 µg, P = 0.02). Nefopam 8.1 [5.0-12.6] mg was used in the C group, while nefopam 12.9 [8.2-22.8] mg was used in the R group (median difference 5.1 mg, 95% CI 0.8-9.7 mg, P = 0.02). The total analgesic consumption: the sum of PCA consumption and administered rescue analgesic dose, converted to morphine milligram equivalents, was higher in the R group than C group (median difference 10.9 mg, 95% CI 3.0-19.0 mg, P = 0.01). The average NRS score, the incidence of PONV and delirium, were similar in both groups. The incidence of intraoperative hypotension was higher in R group than C group (47.1% vs. 20.6%, P = 0.005).

CONCLUSIONS

Remifentanil administration during arthroscopic shoulder surgery in patients undergoing preoperative IBP increased postoperative analgesic consumption.

Impact of Opioid-Free Anesthesia after video-assisted thoracic surgery: a propensity score study

BACKGROUND

Adequate postoperative morphine consumption and pain management after thoracic surgery are major issues in the prevention of respiratory complications. Opioid-free anesthesia (OFA) may decrease morphine consumption and postoperative pain. The objective of this study was to evaluate the impact of OFA on the consumption of morphine and pain after video or robot-assisted thoracic surgery (VATS or RATS).

METHODS

The main objective of this retrospective study with propensity score analysis (PSA) was to compare the cumulative postoperative morphine consumption at 48 hours between a group receiving dexmedetomidine, lidocaine, ketamine (OFA group), and a group receiving remifentanil plus morphine (opioid anesthesia-group (OA)). Postoperative pain at 24 and 48 hours and respiratory and hemodynamics complications were also assessed.

RESULTS

81 patients were included: 48 in the OFA group and 33 in the OA group. The cumulative postoperative morphine consumption at 48 hours was lower in the OFA group than in the OA group (28.50 [0-62.25] mg vs. 55 [34-79.50] mg, P=0.002, with PSA; OFA: -27.67 [-46;-11.50 ] mg, P=0.002). The postoperative pain score was significantly lower in the OFA group compared to the OA group at 24 hours (2 [0-4] vs. 3 [2-5], P=0.064, with PSA; OFA: -1.40 [-2.47;-0.33], P=0.0088) and 48 hours (0 [0-3] vs. 2.5 [0-5], P=0.034, with PSA; OFA:-1.87 [-3.45;-0.28], P=0.021). There were no differences between groups concerning respiratory or hemodynamic complications.

CONCLUSIONS

Our results suggest that OFA after VATS or RATS is safe and is associated with less postoperative morphine cumulative consumption and pain at 48 hours.

Tapentadol versus oxycodone analgesia and side effects after laparoscopic hysterectomy: A randomised controlled trial

BACKGROUND

Tapentadol is an opioid, which acts as a μ-opioid receptor agonist and inhibits noradrenaline reuptake in the central nervous system. This dual mechanism of action results in synergistic analgesic effects and potentially less side effects. This has been shown in treatment of chronic pain but postoperative studies are sparse.

OBJECTIVES

The main aim was to compare the analgesic effect of tapentadol with oxycodone after laparoscopic hysterectomy. Opioid side effects were recorded as secondary outcomes.

DESIGN

Randomised, blinded trial.

SETTING

Single-centre, Oslo University Hospital, Norway, December 2017 to February 2019.

PATIENTS

Eighty-six opioid-naïve American Society of Anesthesiologists physical status 1 to 3 women undergoing laparoscopic hysterectomy for nonmalignant conditions.

INTERVENTION

The patients received either oral tapentadol (group T) or oxycodone (group O) as part of multimodal pain treatment. Extended-release study medicine was administered 1 h preoperatively and after 12 h. Immediate-release study medicine was used as rescue analgesia.

MAIN OUTCOME MEASURES

Pain scores, opioid consumption and opioid-induced side effects were evaluated during the first 24 h after surgery.

RESULTS

The groups scored similarly for pain at rest using a numerical rating scale (NRS) 1 h postoperatively (group T 4.4, 95% CI, 3.8 to 5.0, group O 4.6, 95% CI, 3.8 to 5.3). No statistically significant differences were found between the groups for NRS at rest or while coughing during the 24-h follow-up period (P = 0.857 and P = 0.973). Mean dose of oral rescue medicine was similar for the groups (P = 0.914). Group T had significantly lower odds for nausea at 2 and 3 h postoperatively (P = 0.040, P = 0.020) and less need for antiemetics than group O. No differences were found for respiratory depression, vomiting, dizziness, pruritus, headache or sedation.

CONCLUSION

We found tapentadol to be similar in analgesic efficacy to oxycodone during the first 24 h after hysterectomy, but with significantly less nausea.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03314792.

Postoperative Drip-Infusion of Remifentanil Reduces Postoperative Pain-A Retrospective Observative Study

Development of remifentanil-induced hyperalgesia (RIH) postoperatively is an unpleasant experience that requires further treatment. This study assessed the effects of gradual withdrawal combined with drip infusion of remifentanil on postoperative pain and the requirement for rescue analgesics. A total of 559 patients receiving total intravenous anesthesia with propofol and remifentanil were enrolled. All patients either underwent gradual withdrawal of remifentanil (GWR) or gradual withdrawal combined with drip infusion (GWDR) with a dose of 1 mcg·kg⁻¹ for 30 min after extubation. The numeric rating scale (NRS) and the requirement of rescue analgesics were assessed. The requirement for rescue analgesics was significantly lower in the GWDR group than in the GWR group (13.2% vs. 35.7%; p < 0.001). At the post-anesthetic care unit (PACU), patients in the GWDR group had a lower NRS pain score (p < 0.001). In addition, in the postoperative 2nd hour, patients in the GWDR group had a significantly lower NRS than the GWR group (beta, −0.31; p = 0.003). No remifentanil-related adverse effects were observed. We found that gradual withdrawal combined with drip infusion of remifentanil required less rescue analgesics and reduced pain scores. The new way of remifentanil administration may be effective to prevent RIH.

Persistent Pain After Cardiac Surgery: Prevention and Management

Persistent postoperative pain (PPP) after cardiac surgery is a significant complication that negatively affects patient quality of life and increases health care system burden. However, there are no standards or guidelines to inform how to mitigate these effects. Therefore, in this review, we will discuss strategies to prevent and manage PPP after cardiac surgery. Adequate perioperative analgesia may prove instrumental in the prevention of PPP. Although opioids have historically been the primary analgesic approach to cardiac surgery, an opioid-sparing strategy may prove advantageous in reducing side effects, avoiding secondary hyperalgesia, and decreasing risk of PPP. Implementing a multimodal analgesic plan using alternative medications and regional anesthetic techniques may offer superior efficacy while reducing adverse effects.

Seven-year follow-up of persistent postsurgical pain in cardiac surgery patients: A prospective observational study of prevalence and risk factors

BACKGROUND

Our aim was to describe the long-term prevalence, risk factors and impact on quality of life of persistent postsurgical pain (PPP) following cardiac surgery.

METHODS

All patients undergoing sternotomy in a single centre over 6 months were prospectively interviewed by telephone at six months and seven years following surgery.

RESULTS

We analysed data from 174 patients at six months and 146 patients at seven years following surgery, revealing a PPP prevalence of 39.7% (n = 69) and 9.6% (n = 14) respectively. At six post-operative months, younger age, higher acute pain score, intraoperative remifentanil infusion and more prolonged surgery were associated with sternotomy-site PPP. These variables, in combination, predict PPP in this study group with area under the receiver operating curve of 0.91 (95% CI 0.86-0.94) at 6 months and 0.74 (95% CI 0.57-0.86) at 7 years. Quality of life scores were significantly lower with PPP (median change in EQ-5D score = -0.23 [-0.57, -0.09] compared to 0.00 [0-0.24] without PPP at 7 years, p < 0.001). At7 years, younger age, prolonged surgery and intraoperative remifentanil infusion were associated with sternotomy-site PPP.

CONCLUSIONS

To the best of our knowledge, this is the longest follow-up of PPP across all surgical specialities and certainly within cardiac surgery. Prevalence of PPP and impact on QOL after cardiac surgery are high and associated with young age, high acute pain score, use of remifentanil and long operative time. We present a predictive score to highlight patients at risk of developing PPP.

SIGNIFICANCE

Seven years after cardiac surgery, almost 10% of patients in this cohort described persistent pain in and around the incision. While higher than previous reports in the literature (limited to up to five post-operative years), this assessment was made following three maximal coughs and therefore is movement or function evoked. High incident of persistent postsurgical pain may adversely affect long-term quality of life which is measured using a validated tool.

Effect of dexmedetomidine on Nociception Level Index-guided remifentanil antinociception: A randomised controlled trial

BACKGROUND

The effect of dexmedetomidine on Nociception Level Index-guided (Medasense, Israel) antinociception to reduce intra-operative opioid requirements has not been previously investigated.

OBJECTIVE

We aimed to determine if low-dose dexmedetomidine would reduce remifentanil requirements during Nociception Level Index-guided antinociception without increasing complications associated with dexmedetomidine.

DESIGN

Double-blind randomised controlled trial.

SETTING

Two university teaching hospitals in Brussels, Belgium.

PATIENTS

American Society of Anesthesiologists 1 and 2 patients (n = 58) undergoing maxillofacial or cervicofacial surgery under propofol--remifentanil target-controlled infusion anaesthesia.

INTERVENTIONS

A 30 min infusion of dexmedetomidine, or equal volume of 0.9% NaCl, was infused at 1.2 μg kg-1 h-1 immediately preceding induction and then decreased to 0.6 μg kg-1 h-1 until 30 min before ending surgery. Nociception Level Index and frontal electroencephalogram guided the remifentanil and propofol infusions, respectively.

MAIN OUTCOMES

The primary outcome was the remifentanil requirement. Other outcomes included the propofol requirement, cardiovascular status and postoperative outcome.

RESULTS

Mean ± SD remifentanil (3.96 ± 1.95 vs. 4.42 ± 2.04 ng ml-1; P = 0.0024) and propofol (2.78 ± 1.36 vs. 3.06 ± 1.29 μg ml-1; P = 0.0046) TCI effect site concentrations were lower in the dexmedetomidine group at 30 min postincision and remained lower throughout surgery. When remifentanil (0.133 ± 0.085 vs. 0.198 ± 0.086 μg kg-1 min-1; P = 0.0074) and propofol (5.7 ± 2.72 vs. 7.4 ± 2.80 mg kg-1 h-1; P = 0.0228) requirements are represented as infusion rates, this effect became statistically significant at 2 h postincision.

CONCLUSION

In ASA 1 and 2 patients receiving Nociception Level Index-guided antinociception, dexmedetomidine decreases intra-operative remifentanil requirements. Combined frontal electroencephalogram and Nociception Level Index monitoring can measure dexmedetomidine's hypnotic and opioid-sparing effects during remifentanil-propofol target-controlled infusion anaesthesia.

TRIAL REGISTRATIONS

Clinicaltrials.gov: NCT03912740, EudraCT: 2018-004512-22.

Opioid Use Patterns After Primary Total Knee Replacement

Orthopedic surgeries are associated with the prescription of more narcotics than any other surgical specialty, particularly for total knee replacement (TKR) surgery. The authors examined controlled substance prescriptions following TKR surgery in a sample of 560 TKR patients. Results indicated that of all the 5164 prescriptions documented on the controlled substance monitoring database, 64% were for opioid medications. More than half of the patients received controlled substances from both the surgery site provider and a nonsurgery site provider in the year following surgery. The authors recommend that providers consider the possibility of outside prescribing when prescribing opioid analgesic.

Effects of pupillary reflex dilation-guided opioid administration on remifentanil and morphine consumption during laparoscopic surgery: A randomised controlled trial

BACKGROUND

Analysis of pupillary reflex dilation (PRD) assesses the balance of nociception--antinociception. Laparoscopic surgery induces haemodynamic variations that are misleading. During laparoscopy, PRD guidance helps differentiate haemodynamic changes because of excess nociception from secondary changes related to the reflex release of endocrine factors.

OBJECTIVE

The present study evaluated the effect of PRD-guided antinociception on the administration of intra-operative remifentanil and immediate postoperative morphine consumption in patients undergoing elective laparoscopic surgery.

DESIGN

The study was a single-blind, randomised controlled trial.

SETTING

The study took place at two sites at the University Hospital of Nancy from March 2014 to November 2017.

PATIENTS

A total of 100 patients who underwent scheduled laparoscopic surgery were included.

INTERVENTIONS

Patients were randomly given remifentanil guided by PRD (PRD-guided) or standard anaesthesia care (control).

MAIN OUTCOME MEASURES

The primary outcome was intra-operative remifentanil consumption. Secondary outcomes included morphine consumption in the immediate postoperative period and the number of intra-operative haemodynamic events.

RESULTS

Data from 95 patients were analysed. Intraoperative remifentanil consumption was lower in the PRD-guided group than in the control group: median [IQR], 0.09 [0.07 to 0.11] vs. 0.14 [0.12 to 0.16] μg kg min, with a mean difference (95% confidence Interval, CI) of 0.048 (0.035 to 0.060) μg kg min; P < 0.0001. Morphine consumption was 0.13 [0.1 to 0.5] vs. 0.15 [0.11 to 0.4] mg kg (P = 0.52) in the PRD-guided and control groups, respectively. The number of hypertensive and tachycardia events was greater in the PRD-guided group than in the control group: Hypertensive events 60.4 vs. 32.6%, relative risk 1.85 (95% CI, 1.24 to 2.84), P = 0.004; tachycardia events 31.6% vs. 4.3%, relative risk 2.09 (95% CI, 1.45 to 2.84), P < 0.001.

CONCLUSIONS

When PRD is used to differentiate between haemodynamic events arising from noxious stimuli and those events because of other nonsurgical stimuli, then intra-operative remifentanil administration is reduced intra-operatively during laparoscopic surgery but there was no change in postoperative morphine consumption.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02116868.

Pathway for enhanced recovery after spinal surgery-a systematic review of evidence for use of individual components

Background

Enhanced recovery in spinal surgery (ERSS) has shown promising improvements in clinical and economical outcomes. We have proposed an ERSS pathway based on available evidence. We aimed to delineate the clinical efficacy of individual pathway components in ERSS through a systematic narrative review.

Methods

We included systematic reviews and meta-analysis, randomized controlled trials, non-randomized controlled studies, and observational studies in adults and pediatric patients evaluating any one of the 22 pre-defined components. Our primary outcomes included all-cause mortality, morbidity outcomes (e.g., pulmonary, cardiac, renal, surgical complications), patient-reported outcomes and experiences (e.g., pain, quality of care experience), and health services outcomes (e.g., length of stay and costs). Following databases (1990 onwards) were searched: MEDLINE, EMBASE, and Cochrane Library (Cochrane Database of Systematic Reviews and CENTRAL). Two authors screened the citations, full-text articles, and extracted data. A narrative synthesis was provided. We constructed Evidence Profile (EP) tables for each component of the pathway, where appropriate information was available. Due to clinical and methodological heterogeneity, we did not conduct a meta-analyses. GRADE system was used to classify confidence in cumulative evidence for each component of the pathway.

Results

We identified 5423 relevant studies excluding duplicates as relating to the 22 pre-defined components of enhanced recovery in spinal surgery. We included 664 studies in the systematic review. We identified specific evidence within the context of spinal surgery for 14/22 proposed components. Evidence was summarized in EP tables where suitable. We performed thematic synthesis without EP for 6/22 elements. We identified appropriate societal guidelines for the remainder of the components.

Conclusions

We identified the following components with high quality of evidence as per GRADE system: pre-emptive analgesia, peri-operative blood conservation (antifibrinolytic use), surgical site preparation and antibiotic prophylaxis. There was moderate level of evidence for implementation of prehabilitation, minimally invasive surgery, multimodal perioperative analgesia, intravenous lignocaine and ketamine use as well as early mobilization. This review allows for the first formalized evidence-based unified protocol in the field of ERSS.

Further studies validating the multimodal ERSS framework are essential to guide the future evolution of care in patients undergoing spinal surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01281-1.

Predicting Acute Pain After Surgery: A Multivariate Analysis

OBJECTIVES

To identify perioperative practice patterns that predictably impact postoperative pain.

BACKGROUND

Despite significant advances in perioperative medicine, a significant portion of patients still experience severe pain after major surgery. Postoperative pain is associated with serious adverse outcomes that are costly to patients and society.

METHODS

The presented analysis took advantage of a unique observational data set providing unprecedented detailed pharmacological information. The data were collected by PAIN OUT, a multinational registry project established by the European Commission to improve postoperative pain outcomes. A multivariate approach was used to derive and validate a model predictive of pain on postoperative day 1 (POD1) in 1008 patients undergoing back surgery.

RESULTS

The predictive and validated model was highly significant (P = 8.9E-15) and identified modifiable practice patterns. Importantly, the number of nonopioid analgesic drug classes administered during surgery predicted decreased pain on POD1. At least 2 different nonopioid analgesic drug classes (cyclooxygenase inhibitors, acetaminophen, nefopam, or metamizol) were required to provide meaningful pain relief (>30%). However, only a quarter of patients received at least 2 nonanalgesic drug classes during surgery. In addition, the use of very short-acting opioids predicted increased pain on POD1, suggesting room for improvement in the perioperative management of these patients. Although the model was highly significant, it only accounted for a relatively small fraction of the observed variance.

CONCLUSION

The presented analysis offers detailed insight into current practice patterns and reveals modifications that can be implemented in today's clinical practice. Our results also suggest that parameters other than those currently studied are relevant for postoperative pain including biological and psychological variables.

Intraoperative Remifentanil Infusion and Postoperative Pain Outcomes After Cardiac Surgery-Results from Secondary Analysis of a Randomized, Open-Label Clinical Trial

DESIGN

Report of secondary pain outcomes from a prospective, randomized, open-label clinical trial that compared remifentanil and fentanyl on perioperative hyperglycemic response in cardiac surgery.

SETTING

Single institution, tertiary university hospital.

PARTICIPANTS

The study comprised 116 adult elective cardiac surgical patients.

INTERVENTIONS

Participants were randomly assigned to receive either intermittent fentanyl boluses (F) or continuous remifentanil infusion (R) intraoperatively.

MEASUREMENTS AND MAIN RESULTS

Postoperative pain was evaluated with pain scores every 6 hours for 48 hours. Pain threshold to mechanical stimuli was measured around the sternotomy incision at 48 and 96 hours. The development of chronic pain was assessed using the numeric rating scale at 1, 3, 6, and 12 months after discharge. The final analysis included 106 patients. Pain scores and wound hyperalgesia were not significantly different postoperatively between the groups. The incidence of chronic pain at 3 months was comparable in both groups (61% in group F v 58% in group R; p = 0.79). Pain of more-than-mild degree was seen in 13 (32%) patients in group F and 8 (19%) in group R (p = 0.25) at 3 months. Median pain scores were not significantly different between the groups at 1, 3, 6, and 12 months after discharge from the hospital.

CONCLUSIONS

The present study's findings suggested that intraoperative remifentanil infusion does not significantly worsen pain outcomes in patients undergoing elective cardiac surgery.

Soft drugs in anesthesia: remifentanil as prototype to modern anesthetic drug development

PURPOSE OF REVIEW

The unique demands of modern anesthesia practice require that medications be effective, well tolerated, and efficient. These attributes are increasingly achieved with the soft drug approach, wherein novel active compounds are specifically designed to be susceptible to rapid biotransformation to inactive metabolites. The present review summarizes the historical background and recent trends in soft drug development in anesthesiology.

RECENT FINDINGS

Soft drug development programs for propranadid, etomidate, and benzodiazepine analogues have been undertaken in recent years. Although all three drugs advanced into human trials, neuro-excitatory adverse effects hampered the propranadid and etomidate analogue projects. Remimazolam, the soft benzodiazepine analogue, is at an advanced stage of development, having already received regulatory approval or review in several countries.

SUMMARY

With succinylcholine as the historical forerunner and remifentanil as the modern prototype, the soft drug paradigm continues to hold promise for the future of anesthesia drug development.

Preemptive analgesia with a single low dose of intrathecal morphine in multilevel posterior lumbar interbody fusion surgery: a double-blind, randomized, controlled trial

BACKGROUND CONTEXT

Patients undergoing lumbar spinal surgery may experience considerable pain in the early postoperative period, and poor pain control after multilevel lumbar spinal fusion surgery is frequently associated with multiple complications and delayed discharge from hospital.

PURPOSE

The current study evaluated the efficacy and safety of preemptive analgesia with intrathecal morphine (ITM) in patients undergoing multilevel posterior lumbar spinal fusion surgery.

STUDY DESIGN

Double-blinded, randomized, controlled trial.

PATIENT SAMPLE

Ninety-two patients aged between 18 and 80 years who were scheduled to undergo elective lumbar laminectomy (L3-S1) and dual-level fusions.

OUTCOME MEASURES

The primary endpoint was the degree of postoperative pain at rest and during movement evaluated using a 10-point visual analogue scale. The secondary outcomes included the consumption of analgesics, the patient-assessed postoperative and satisfaction scores, adverse effects, time to first ambulation, and length of hospital stay.

METHODS

Patients were randomly allocated to either the ITM group that received 0.2 mg of ITM or the control (CON) group that received 2 ml of 0.9% saline as a skin infiltration 30 minutes prior to anesthesia induction.

RESULTS

The ITM group had a significantly lower visual analogue scale score than the CON group during the first 3 days postoperatively (at rest, P=0.000, during movement, P=0.000). The ITM group used significantly less sufentanil than the CON group in the first 3 days postoperatively (p=.000) in patient-controlled intravenous analgesia, as well as in supplemental analgesic demands. The ITM group reported a greater degree of satisfaction with the whole hospitalization experience than the CON group (2.4±0.6 vs. 1.9±0.6, p=.000). The two groups did not significantly differ regarding adverse effects, length of hospital stay, and time taken to regain the ability to walk without support.

CONCLUSIONS

Preemptive analgesia with ITM results in significantly improved early postoperative pain control and decreased postoperative patient-controlled intravenous analgesia consumption, with no increase in adverse effects.

Persistent pain in intensive care survivors: a systematic review

BACKGROUND

According to earlier studies where the main aim has been quality of life, there is growing evidence of increased levels of persistent pain in survivors of critical illness. The cause of admission and several factors during intensive care may have associated risk factors for pain persistence. This systematic review aims to determine the incidence or prevalence of persistent pain after critical illness and to identify risk factors for it.

METHODS

Six databases were searched, and eventually nine studies were included in the final systematic process. The validity of observational and cross-sectional studies was analysed using the National Institute of Health 'Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies'.

RESULTS

The incidence of persistent pain after intensive care varied from 28% to 77%. Risk factors for persistent pain were acute pain at discharge from ICU, higher thoracic trauma score, surgery, pre-existing pain, organ failure, longer length of ventilator or hospital stay, and sepsis. No difference in incidence between medical and surgical patients was found.

CONCLUSIONS

New systematic, observational studies are warranted to identify persistent pain-related factors in intensive care to improve pain management protocols and thereby diminish the risk of persistent pain after ICU stay.

Comparison between total intravenous anesthesia and balanced anesthesia on postoperative opioid consumption in patients who underwent laparoscopic-assisted distal gastrectomy

Remifentanil is the most frequently prescribed opioid for total intravenous anesthesia (TIVA) or balanced anesthesia (BA), due to its favorable pharmacological properties. However, several studies have reported opioid-induced hyperalgesia and/or acute tolerance after intraoperatively using remifentanil. In addition, it is imperative to control postoperative pain with lower doses of opioid anesthetic agents. Therefore, we compared the amount of opioid consumption between TIVA with propofol-remifentanil and BA with desflurane-remifentanil, to control postoperative pain in patients who underwent laparoscopic-assisted distal gastrectomy (LADG) with gastroduodenostomy.We retrospectively evaluated demographic variables (age, gender, height, weight, and smoking habits), the duration of general anesthesia (GA), and intraoperatively administered remifentanil consumption through the electronic medical records of patients who underwent LADG with gastroduodenostomy due to early stomach cancer. The primary outcome was postoperative opioid consumption during postoperative day (POD) 2. The secondary outcomes were the incidence of any rescue opioid analgesics administered, numeric rating scale, and various adverse effects during POD 2. We categorized the data in 2 patient groups to compare TIVA with propofol-remifentanil (TIVA group) to BA with desflurane-remifentanil (BA group) on the postoperative opioid analgesic consumption.We divided 114 patients into the TIVA (46 patients) and BA (68 patients) groups. Opioid consumption as a primary outcome was significantly higher in the BA group than in the TIVA group during POD 2 except in the post-anesthesia care unit. The cumulative opioid consumption was significantly higher in the BA than in the TIVA group. The incidence of rescue analgesic at POD 2 was higher in the BA than in the TIVA group. In the TIVA group, remifentanil consumption was higher, and the duration of GA was shorter than that in the BA group. No statistically significant differences were observed when comparing other variables.Our results indicated that the maintenance of GA with TIVA (propofol-remifentanil) reduces opioid consumption for postoperative pain control compared to BA (desflurane-remifentanil) in patients undergoing LADG with gastroduodenostomy.

Lack of Efficacy: When Opioids Do Not Achieve Analgesia from the Beginning of Treatment in Cancer Patients

Introduction

Opioids are often used to relieve moderate to severe pain, but their analgesic response may vary. We focused on the absolute lack of analgesic response immediately after beginning opioid treatment, quantifying the proportion of patients with unchanged or worse pain on day 3 (defined as early non-responders (ENRs)) and day 7.

Methods

This is a post-hoc analysis from a randomized controlled trial involving 498 cancer patients with pain, starting to receive WHO step III opioids. On days 1, 3 and 7 pain intensity (PI) was measured.

Results

On day 3, 68 (13.7%) patients were ENRs, 53 no change and 15 greater PI compared to baseline. The relationships between pain and clinical characteristics showed no significant differences between ENRs and Early responders (ERs), except for PI at baseline, which was significantly lower in ENRs. ENRs on day 3 were re-assessed on day 7 to explore the patterns of analgesic response: 31.7% of patients remained NRs, 48.3% had become responders, and 20.0% were poor responders. Adverse drug reactions were similar in ERs and ENRs at each visit.

Discussion

The complete lack of early response to opioids in cancer patients is clinically important and more frequent than expected. Better definition of the mechanism will allow better pain management in cancer and non-cancer patients.

Pain and Its Long-term Interference of Daily Life After Critical Illness

BACKGROUND

Persistent pain likely interferes with quality of life in survivors of critical illness, but data are limited on its prevalence and risk factors. We sought to determine the prevalence of persistent pain after critical illness and its interference with daily life. Additionally, we sought to determine if intensive care unit (ICU) opioid exposure is a risk factor for its development.

METHODS

In a cohort of adult medical and surgical ICU survivors, we used the brief pain inventory (BPI) to assess pain intensity and pain interference of daily life at 3 and 12 months after hospital discharge. We used proportional odds logistic regression with Bonferroni correction to evaluate the independent association of ICU opioid exposure with BPI scores, adjusting for potential confounders including age, preadmission opioid use, frailty, surgery, severity of illness, and durations of delirium and sepsis while in the ICU.

RESULTS

We obtained BPI outcomes in 295 patients overall. At 3 and 12 months, 77% and 74% of patients reported persistent pain symptoms, respectively. The median (interquartile range) pain intensity score was 3 (1, 5) at both 3 and 12 months. Pain interference with daily life was reported in 59% and 62% of patients at 3 and 12 months, respectively. The median overall pain interference score was 2 (0, 5) at both 3 and 12 months. ICU opioid exposure was not associated with increased pain intensity at 3 months (odds ratio [OR; 95% confidence interval], 2.12 [0.92-4.93]; P = .18) or 12 months (OR, 2.58 [1.26-5.29]; P = .04). ICU opioid exposure was not associated with increased pain interference of daily life at 3 months (OR, 1.48 [0.65-3.38]; P = .64) or 12 months (OR, 1.46 [0.72-2.96]; P = .58).

CONCLUSIONS

Persistent pain is prevalent after critical illness and frequently interferes with daily life. Increased ICU opioid exposure was not associated with worse pain symptoms. Further studies are needed to identify modifiable risk factors for persistent pain in the critically ill and the effects of ICU opioids on patients with and without chronic pain.

Remifentanil-Sparing Effect of Pectoral Nerve Block Type II in Breast Surgery under Surgical Pleth Index-Guided Analgesia during Total Intravenous Anesthesia

The pectoral nerve block type II (Pecs II block) can provide adequate perioperative analgesia in breast surgery. The surgical pleth index (SPI) is used to monitor the nociception balance using pulse oximetry. We investigated the remifentanil-sparing effect of Pecs II block under SPI guided analgesia during total intravenous anesthesia (TIVA). Thirty-nine patients undergoing breast surgery under remifentanil-propofol anesthesia were randomly assigned to the intervention (Pecs group, n = 20) or control group (n = 19). Remifentanil and propofol concentrations were adjusted to maintain an SPI of 20–50 and a bispectral index of 40–60, respectively. The Pecs group received an ultrasound-guided Pecs II block preoperatively using 30 mL of 0.5% ropivacaine. Total infused remifentanil during the surgery was significantly less in the Pecs group than in the control group (6.8 ± 2.2 μg/kg/h vs. 10.1 ± 3.7 μg/kg/h, p = 0.001). Pain scores on arrival at the postanesthetic care unit (PACU) (3 (2–5) vs. 5 (4–7)) and the rescue analgesic requirement in the PACU (9 vs. 2) was significantly lower in the Pecs group than in the control group. In conclusion, Pecs II block was able to reduce the intraoperative remifentanil consumption by approximately 30% and improve the postoperative pain in PACU in patients undergoing breast surgery under SPI-guided analgesia during TIVA.

Preemptive oxycodone is superior to equal dose of sufentanil to reduce visceral pain and inflammatory markers after surgery: a randomized controlled trail

Background

Postoperative visceral pain is common after surgery and previous studies have demonstrated that oxycodone is an effective treatment. In this study, we compared the effects of preemptive oxycodone to equal dose of sufentanil on postoperative pain and serum level of inflammatory factors (TNF-α, IL-6, IL-10) after laparoscopic cholecystectomy.

Methods

Forty patients undergoing laparoscopic cholecystectomy were randomized into preemptive oxycodone group or preemptive sufentanil group.

Patients were given either oxycodone 0.1 mg/kg (oxycodone group, n = 20) or sufentanil 0.1 μg/kg (sufentanil group, n = 20) for preemptive analgesia. We evaluated pain/sedation scores at 0 h, 0.5 h, 2 h, 4 h, 6 h, 8 h and 24 h after surgery and measured serum concentrations of TNF-α, IL-6 and IL-10 before surgery and at 0 h, 6 h and 24 h after surgery.

Results

Twenty patients were recruited in each group. Numerical rating scale (NRS) of visceral pain in the oxycodone group at 2 h when resting (0.5(0,2.75) vs 3(2,4), P = 0.008) and moving (0.5(0,3) vs 3(2.25,4), P = 0.015) and 4 h when moving (2(0,3) vs 3(0,4.75), P = 0.043) after surgery were significantly lower than the sufentanil group. Serum concentrations of TNF-α at 6 h (38.68 ± 10.49 vs 73.02 ± 16.27, P<0.001) and 24 h (43.12 ± 8.40 vs 74.00 ± 21.30, P<0.001) in the oxycodone group were lower than the sufentanil group.

Conclusions

Preemptive oxycodone 0.1 mg/kg administration could effectively suppress visceral pain at 2 h and 4 h after surgery and had lower inflammatory marker, serum TNF-α, level when compared to equal dose of sufentanil.

Trial registration

Clinical trials registration number: ChiCTR-IOR-17013738http://www.chictr.org.cn/showproj.aspx?proj=17346. Date of registration: 6th December 2017.

Intensity of Withdrawal Symptoms During Opioid Taper in Patients with Chronic Pain—Individualized or Fixed Starting Dosage?

Objective

Controlled opioid withdrawal is recommended for patients with chronic noncancer pain (CNCP) with insufficient pain reduction or intolerable side effects while on opioid treatment. Few studies have investigated the management of opioid withdrawal (OW). Most common are protocols with an individualized starting dosage (ISD), calculated from the last opioid intake. After two cases of overdose, we introduced a novel withdrawal protocol using a low fixed starting dosage (FSD) for safety reasons. The present study compares the intensity of withdrawal symptoms using the Subjective Opioid Withdrawal Scale (SOWS) and incidences of serious adverse events (SAE) and dropouts in each taper schedule in 195 CNCP patients with OW in an inpatient facility.

Methods

Two protocols were compared: FSD (2014–2016): N = 68, starting dose: 90 mg morphine/d; and ISD (2010–2014): N = 127, starting dose: 70% of the patient’s daily morphine equivalent dose (MED). Outcome criteria: primary: mean daily SOWS score during the first 10 days (16 questions, daily score 0–64); secondary: change in pain intensity on a numeric rating scale (0–10), rate of dropouts and SAEs. Statistics: Student test, Mann-Whitney U test, chi-square test, analysis of variance, P &lt; 0.05.

Results

The mean daily SOWS score was lower in the FSD group (14.9 ± 9.4 vs 16.1 ± 10, P &lt; 0.05) due to a lower rate of high-intensity withdrawal symptoms (12.4% vs 17.6%, P &lt; 0.01), particularly in patients on &gt;180 mg MED (9.7% vs 18.4%, P &lt; 0.01). Pain intensity decreased after withdrawal, and the incidence of SAEs and dropouts was low in both groups.

Conclusions

The FSD protocol provides a lesser burden of withdrawal symptoms and equal patient safety. It can be recommended for OW in CNCP patients.

Effects of low-dose ketamine infusion on remifentanil-induced acute opioid tolerance and the inflammatory response in patients undergoing orthognathic surgery

Purpose

Remifentanil is associated with acute opioid tolerance that can lead to increased postoperative consumption of opioid analgesics. The purpose of this study was to determine whether a low dose of ketamine prevents remifentanil-induced acute opioid tolerance and affects the neutrophil–lymphocyte ratio (NLR), a newly recognized biomarker of inflammation.

Materials and methods

Forty patients undergoing orthognathic surgery were enrolled in this prospective, randomized, double-blind study and randomly assigned to intraoperative administration of one of the following anesthetic regimens: high-dose remifentanil (0.6 µg/kg/minute); low-dose remifentanil (0.2 µg/kg/minute); or high-dose remifentanil with ketamine (remifentanil 0.6 µg/kg/minute with 0.5 mg/kg ketamine just after induction followed by an intraoperative infusion of ketamine 5 µg/kg/minute until wound closure). Fentanyl by intravenous patient-controlled analgesia was used for postoperative pain control. Visual Analog Scale pain scores and fentanyl consumption were recorded in the first 24 hours postoperatively. Perioperative serum C-reactive protein level and NLR were also determined.

Results

Baseline characteristics were similar in the three study groups. There were no between-group differences in Visual Analog Scale pain scores during the study period. The high-dose remifentanil group had a significantly higher requirement for fentanyl than the other two groups. Addition of ketamine did not affect the C-reactive protein level but increased the NLR; this increase was associated with decreased fentanyl consumption.

Conclusion

High-dose intraoperative remifentanil induced postoperative acute opioid tolerance that was prevented by infusion of low-dose ketamine. Ketamine increased the postoperative NLR associated with decreased fentanyl requirement for postoperative pain control.

Excessive remifentanil during total intravenous anesthesia is associated with increased risk of pain after robotic thyroid surgery

The widespread use of remifentanil during total intravenous anesthesia (TIVA) has raised concerns about the risk of postoperative remifentanil-associated pain. Although a recent meta-analysis suggests that remifentanil-associated pain is unlikely to occur in patients with TIVA because of the protective effect of co-administered propofol, the evidence is not conclusive. We retrospectively assessed 635 patients who received robotic thyroid surgery under TIVA to evaluate the risk of remifentanil-associated pain. Postoperative pain was evaluated using 11-point numeric rating scale (NRS). Time dependent Cox proportional hazards regression analysis was used to determine the risk factors of treatment-requiring pain (NRS > 4) during the first 48 postoperative hours. Postoperative pain rapidly decreased, and treatment-requiring pain remained in 12.8% (81 out of 635) of patients at 48 hours postoperatively. After adjusting for the time-dependent analgesic consumption, intraoperative use of remifentanil > 0.2 mcg/kg/min was a positive predictor of postoperative pain with a hazard ratio of 1.296 (95% C.I., 1.014–1.656, P = 0.039) during 48 hours after surgery. In conclusion, excessive use of remifentanil during TIVA was associated with increased risk of pain after robotic thyroid surgery. Prospective trials are required to confirm these results and determine whether decreasing remifentanil consumption below the threshold can reduce postoperative pain.

The influence of high-dose intraoperative remifentanil on postoperative sore throat: a prospective randomized study: A CONSORT compliant article

BACKGROUND

Endotracheal intubation for general anesthesia causes postoperative sore throat (POST). This study is designed to evaluate the effect of high-dose remifentanil on the incidence of POST in patients after general anesthesia.

METHODS

Ninety-two patients scheduled for orthopedic lower extremity surgery under general anesthesia were randomly assigned into 1 of 2 groups. In the high-dose remifentanil (HR) group (n = 46), remifentanil was infused at a rate of 0.25 μg/kg/min and subsequently increased or decreased by 0.05 μg/kg/min per clinical demand. In the low-dose remifentanil (LR) group (n = 46), remifentanil was infused at a rate of 0.05 μg/kg/min. The incidence of POST was monitored at 0, 2, 4, and 24 hours postoperatively. Complications regarding opioids were compared between groups.

RESULTS

The overall incidence of POST was higher in the HR group compared with that in the LR group [33 (72%) vs 18 (39%), P = .022]. The incidence of POST at 0, 2, and 24 hours after surgery was higher in the HR group compared with that in the LR group (P < .001, P = .001, and P = .001, respectively). The incidence of postoperative nausea, vomiting, drowsiness, and headache was similar between the groups. The incidence of postoperative shivering was higher in the HR group than in the LR group [10 (22%) vs 2 (4%), difference 17%, 95% CI 2%-33%, P = .027].

CONCLUSION

A relatively large dose of intraoperative remifentanil increased the incidence of POST in patients for orthopedic surgery under general anesthesia.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT03173339.

Scheduled Intravenous Acetaminophen Improves Patient Satisfaction With Postcraniotomy Pain Management: A Prospective, Randomized, Placebo-controlled, Double-blind Study

BACKGROUND

Postcraniotomy pain can be difficult to manage with opioids due to opioid-related side effects, including drowsiness, nausea/vomiting, confusion, and pupillary changes, potentially masking the signs of postoperative neurological deterioration. Intravenous (IV) acetaminophen, a nonopioid analgesic, has been reported to have opioid-sparing effects after abdominal and orthopedic surgeries. This study investigates whether IV acetaminophen has similar effects after craniotomy.

MATERIALS AND METHODS

In this prospective, randomized, placebo-controlled, double-blind clinical trial, 100 adult patients scheduled to undergo supratentorial craniotomy for excision of a brain mass were randomized to receive either IV acetaminophen or placebo preincision and then every 6 hours for a total of 24 hours after surgery. Total 24-hour opioid consumption, pain scores, satisfaction with overall pain management, time to meet postanesthesia care unit discharge criteria, and incidence of opioid-related side effects were compared.

RESULTS

There was no difference in the 24-hour postoperative opioid consumption in morphine equivalents between the IV acetaminophen group (median, 11 mg; n=45) and the placebo group (median, 10.1 mg; n=41). No statistically significant difference of visual analog scale pain score was observed between 2 treatment groups. Patient satisfaction with overall postoperative pain management was significantly higher in the IV acetaminophen group than the placebo group on a 1 to 10 scale (8.1±0.4 vs. 6.9±0.4; P=0.03). There was no significant difference in secondary outcomes, including the incidence of opioid-related side effects.

CONCLUSIONS

IV acetaminophen, as adjunctive therapy for craniotomy procedures, did not show an opioid-sparing effect in patients for the 24 hours after craniotomy; however, it was associated with improved patient satisfaction regarding overall pain control.

New concepts in opioid analgesia

INTRODUCTION

Opioids are the oldest and most potent drugs for the treatment of severe pain, but they are burdened by detrimental side effects such as respiratory depression, addiction, sedation, nausea, and constipation. Their clinical application is undisputed in acute (e.g. perioperative) and cancer pain, but their long-term use in chronic pain has met increasing scrutiny and has contributed to the current 'opioid crisis.'

AREAS COVERED

This article reviews pharmacological principles and research strategies aiming at novel opioids with reduced side effects. Basic mechanisms underlying pain, opioid analgesia, and other opioid actions are outlined. To illustrate the clinical situation and medical needs, plasticity of opioid receptors, intracellular signaling pathways, endogenous and exogenous opioid receptor ligands, central and peripheral sites of analgesic, and side effects are discussed.

EXPERT OPINION

The epidemic of opioid misuse has taught us that there is a lack of fundamental knowledge about the characteristics and management of chronic pain, that conflicts of interest and validity of models must be considered in the context of drug development, and that novel analgesics with less abuse liability are badly needed. Currently, the most promising perspectives appear to be augmenting endogenous opioid actions and selectively targeting pathological conformations of peripheral opioid receptors.

The increased release of amino acid neurotransmitters of the primary somatosensory cortical area in rats contributes to remifentanil-induced hyperalgesia and its inhibition by lidocaine

Background

Studies have confirmed that activation of the neurons of primary somatosensory cortex (S1) is involved in the process of remifentanil (Remi)-induced hyperalgesia (RIH), which can be suppressed by lidocaine (Lido). A total intravenous anesthesia model of rats mimicking clinical Remi-based anesthesia was set up to explore the release of amino acid neurotransmitters of S1 cortex in RIH and its inhibition by Lido in this study.

Materials and methods

Sprague Dawley rats were randomly divided into the following four groups: propofol (Pro), Remi, Remi combined Lido, and Lido groups. Mechanical hyperalgesia was evaluated by von Frey test; the amino acid neurotransmitters in the microdialysates of S1 area were detected by high-performance liquid chromatography (HPLC)-fluorescence, and conventional protein kinase C (cPKC)γ levels in the whole-cell lysates and membrane lipid rafts (MLRs) were determined by Western blotting.

Results

The von Frey test showed that co-administration of Lido significantly inhibited a Remi-induced decrease in the threshold of the paw withdrawal response in Remi group at 2 h postinfusion. Meanwhile, the Remi-induced increases in both the excitatory and inhibitory amino acid releases in S1 were suppressed by co-administrating Lido within 5 h postinfusion. Western blotting showed that the increased cPKCγ level in the membrane lipid rafts (MLR) induced by Remi was also inhibited by Lido.

Conclusion

The increased release of amino acid neurotransmitters and the translocation of cPKCγ in MLR suggest the activation of S1 neurons, which may be one of the mechanisms underlying RIH. Lido reduces the release of amino acid neurotransmitters in S1 neurons and the translocation of cPKCγ in MLRs after stopping Remi, which may be one of its antihyperalgesic mechanisms.

Opioid-induced hyperalgesia in clinical anesthesia practice: what has remained from theoretical concepts and experimental studies?

PURPOSE OF REVIEW

This article reviews the phenomenon of opioid-induced hyperalgesia (OIH) and its implications for clinical anesthesia. The goal of this review is to give an update on perioperative prevention and treatment strategies, based on findings in preclinical and clinical research.

RECENT FINDINGS

Several systems have been suggested to be involved in the pathophysiology of OIH with a focus on the glutaminergic system. Very recently preclinical data revealed that peripheral μ-opioid receptors (MORs) are key players in the development of OIH and acute opioid tolerance (AOT). Peripheral MOR antagonists could, thus, become a new prevention/treatment option of OIH in the perioperative setting. Although the impact of OIH on postoperative pain seems to be moderate, recent evidence suggests that increased hyperalgesia following opioid treatment correlates with the risk of developing persistent pain after surgery. In clinical practice, distinction among OIH, AOT and acute opioid withdrawal remains difficult, especially because a specific quantitative sensory test to diagnose OIH has not been validated yet.

SUMMARY

Since the immediate postoperative period is not ideal to initiate long-term treatment for OIH, the best strategy is to prevent its occurrence. A multimodal approach, including choice of opioid, dose limitations and addition of nonopioid analgesics, is recommended.