Remifentanil for abdominal surgery is associated with unexpectedly unfavorable outcomes

Dexmedetomidine Alleviates Remifentanil-Induced Hyperalgesia in Rats by Modulating the P2 X 4/BDNF Pathway

In the clinical settings, patients often develop opioid-induced hyperalgesia (OIH) after utilization of high dose intra-operative remifentanil. It is widely considered that systemic α2 agonists, including dexmedetomidine (DEX), have the potential to mitigate postoperative pain and minimize the needs for opioid, thus leading to a decrease in the incidence of hyperalgesia. However, the regulating method remains ambiguous. Recent studies have shown that DEX can alleviate spinal nerve injury via regulating P2 X 4. Although the effects of DEX on remifentanil-induced hyperalgesia (RIH) have been previously reported, the specific mechanisms remain to be fully elucidated. The objective of our study was to investigate the potential of intraperitoneal injections of DEX in attenuate RIH in rats through the modulation of P2 X 4Rs and brain-derived neurotrophic factor (BDNF) in spinal cord. The findings of this study indicate that intraperitoneal administration of DEX at a dosage of 50 µg/kg could alleviate mechanical allodynia and thermal hyperalgesia, as demonstrated through a behavioral test. Moreover, DEX suppressed the enhancement of P2 X 4 and BDNF expression induced by RIH. Furthermore, the structure of synaptic clefts caused by RIH showed improvement to a certain extent after DEX treatment, as shown using TEM transmission electron microscopy. In summary, we examined the protective effect of DEX on remifentanil-induced hyperalgesia. The findings indicates that the reduced expression of P2 X 4 and decreased synthesis and release of BDNF may be responsible for the analgesic processes. This study would provide a new perspective and strategy for the pharmacological treatment on RIH.

Opioid-Free Using Ketamine versus Opioid-Sparing Anesthesia during the Intraoperative Period in Video-Assisted Thoracoscopic Surgery: A Randomized Controlled Trial

Opioids effectively manage perioperative pain but have numerous adverse effects. Opioid-free anesthesia (OFA) eliminates intraoperative opioid use; however, evidence for its use in video-assisted thoracoscopic surgery (VATS) is limited. This study assessed the effect of OFA using ketamine in VATS patients compared to opioid-sparing anesthesia (OSA). A total of 91 patients undergoing VATS lobectomy or segmentectomy were randomized to either the OFA group (ketamine) or the OSA group (remifentanil). The primary outcome was the quality of recovery (QoR) on postoperative day (POD) 1, measured with the QoR-40 questionnaire. Secondary outcomes included postoperative pain scores and adverse events. Both groups had comparable baseline and surgical characteristics. On POD 1, the QoR-40 score was higher in the OFA group than in the OSA group (164.3 ± 10.8 vs. 158.7 ± 10.6; mean difference: 5.6, 95% CI: 1.1, 10.0; p = 0.015), though this did not meet the pre-specified minimal clinically important difference of 6.3. The visual analog scale score was lower in the OFA group as compared to the OSA group at 0-1 h (4.2 ± 2.3 vs. 6.2 ± 2.1; p < 0.001) and 1-4 h after surgery (3.4 ± 1.8 vs. 4.6 ± 1.9; p = 0.003). The OFA group had a lower incidence of PONV (2 [4.4%] vs. 9 [19.6%]; p = 0.049) and postoperative shivering (4 [8.9%] vs. 13 [28.3%]; p = 0.030) than the OSA group at 0-1 h after surgery. Using OFA with ketamine proved feasible, as indicated by the stable intraoperative hemodynamics and absence of intraoperative awareness. Patients undergoing VATS with OFA using ketamine showed a statistically significant, but clinically insignificant, QoR improvement compared to those receiving OSA with remifentanil.

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.

Persistent Postpartum Pain - A Somatic and Psychologic Perfect Storm

Persistent postpartum pain is common and has a complex etiology. It has both somatic and psychosocial provoking factors and has both functional and psychological ramifications following childbirth. Pain that limits the functional capacity of a person who has the daunting task to take care of all the demands of managing a growing newborn and infant can have debilitating consequences for several people simultaneously. We will review the incidence of persistent postpartum pain, analyze the risk factors, and discuss obstetric, anesthetic, and psychological tools for prevention and management. Based on the current knowledge, early antenatal screening and management is described as the most likely measure to identify patients at risk for persistent postpartum pain. Such antenatal management should be based on the close collaboration between obstetricians, anesthesiologists, and psychologists to tailor peripartum pain management and psychological support-based individual needs.

The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac

Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.

Opioid infusions at different times of the day produce varying degrees of opioid-induced hyperalgesia

BACKGROUND

Opioids are metabolised by enzymes the activities of which vary with the circadian rhythm. We examined whether opioid infusions administered at different times of the day produce varying degrees of opioid-induced hyperalgesia (OIH) in animal experiments and clinical studies.

METHODS

Male Sprague-Dawley rats received remifentanil infusions (1 μg kg-1·min-1 for 1 h) at Zeitgeber times (ZT) 0, 4, 8, 12, 16, or 20 h. Rhythmicity of mechanical hypersensitivity was assayed after the infusion. Mechanical hypersensitivity, drug concentration, and metabolic enzyme activity of Wistar rats that received sufentanil (10 μg kg-1; four consecutive i.p. injections at 15-min intervals) or remifentanil infusion at ZT0 or ZT8 were assayed. Sixty patients who underwent abdominal laparoscopic surgery under general anaesthesia received remifentanil infusion (0.15 μg kg-1 min-1) and sufentanil injection (0.2 μg kg-1) at induction and skin incision, respectively. Postoperative pressure pain sensitivity, pain Numeric Rating Scale (NRS), drug concentrations, and nonspecific esterase activity were assessed.

RESULTS

Sprague-Dawley rats that received remifentanil infusion exhibited a robust rhythmic paw withdrawal threshold (JTK_CYCLE: P=0.001, Q=0.001, Phase=26). Wistar rats infused with remifentanil or sufentanil at ZT8 exhibited greater OIH (P<0.001) than those infused at ZT0, with higher blood concentrations (P<0.001) and lower metabolic enzyme activities (P=0.026 and P=0.028, respectively). Patients in the afternoon group exhibited higher pressure pain sensitivity at forearm (P=0.002), higher NRS (P<0.05), higher drug concentrations (sufentanil: P=0.037, remifentanil: P=0.005), and lower nonspecific esterase activity (P=0.024) than the morning group.

CONCLUSIONS

Opioid infusions administered at different times of day produced varying degrees of OIH, possibly related to circadian rhythms of metabolic enzyme activities.

CLINICAL TRIAL REGISTRATION

NCT05234697.

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.

Intra-articular remifentanil on postoperative pain in knee arthroscopic surgery; a double blind randomized clinical trial

BACKGROUND

We aimed to assess the efficacy of intra-articular remifentanil in relieving postoperative pain after knee arthroscopy.

METHODS

We conducted a double-blind randomized clinical trial study on 60 patients. Patients were divided into two equal groups. The control group received 25 ml of intra-articular normal saline, and the intervention group received 200 μg of remifentanil dissolved in 25 ml of saline. We evaluated at rest postoperative pain at 1, 3, 6, 12, 18, and 24 h after the surgery using the Visual Analog Scale (VAS). Patients with VAS scores of 4 or more received meperidine (pethidine). The first time meperidine was requested and the total amount of meperidine consumed was recorded.

RESULTS

Out of 60 patients, 49 were male (81.6%), and the mean age of participants was 32.71 (7.02) years. An hour after the surgery, the control group showed a mean VAS score of 8.66 (1.26), and decreased to 2.53 (1.67) at the end of 24 h. The intervention group started with a mean VAS score of 2.23 (1.81) and ended at 0.10 (0.305). All patients in the control group and 11 (36.7%) patients in the intervention group asked for analgesics during follow-up. The mean total meperidine dose in the control and intervention groups was 108.33 (23.97) mg and 13.33 (19.40) mg, respectively (P < 0.001; 95% confidence interval of the difference 83.72 to 106.27).

CONCLUSIONS

Intra-articular remifentanil may decrease postoperative pain and analgesic requirements in patients undergoing knee arthroscopy.

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

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

Remifentanil does not affect human microglial immune activation in response to pro-inflammatory cytokines

Remifentanil is a potent ultra-short acting μ-opioid analgesic drug, frequently used in anaesthesia due to its favorable pharmacodynamic and pharmacokinetic profile. It may be associated with the occurrence of hyperalgesia. Preclinical studies suggest a potential role of microglia, although the molecular mechanisms have not been fully elucidated. Considering the role of microglia in brain inflammation and the relevant differences among species, the effects of remifentanil were studied on the human microglial C20 cells. The drug was tested at clinically relevant concentrations under basal and inflammatory conditions. In the C20 cells, the expression and secretion of interleukin 6, interleukin 8 and the monocyte chemotactic protein 1 were rapidly induced by a mixture of pro-inflammatory cytokines. This stimulatory effect was sustained up to 24 h. Remifentanil did not exert any toxic effect nor modify the production of these inflammatory mediators, thus suggesting the lack of direct immune modulatory actions on human microglia.

Predictors of Postoperative Nausea and Vomiting After Same-Day Surgery: A Retrospective Study

PURPOSE

Postoperative nausea and vomiting (PONV) are main issues after same-day surgery. This study aimed to retrospectively evaluate the electronic medical records of patients who underwent same-day operations under general anesthesia to identify the potential risk factors for PONV.

METHODS

Records of 7759 adult patients who received general anesthesia with remifentanil were reviewed. The patients were assessed for the incidence and severity of PONV. Multiple logistic regression was used to identify risk factors for PONV. A nomogram was established to predict PONV after same-day operations.

FINDINGS

Of 7759 patients, 2317 (29.9%) experienced PONV. In multiple logistic regression analysis, female sex, nonsmoker status, history of motion sickness or nausea, high body mass index (BMI), long surgical duration, laparoscopic procedure, and preoperative analgesic intake within 30 days were independent risk factors for PONV. No correlation was found between the severity of PONV and remifentanil exposure (odds ratio = 1.018; 95% CI, 0.861-1.204; P = 0.834) or remifentanil dose (odds ratio = 1.294; 95% CI, 0.760-2.205; P = 0.343). For the nomogram, which involved sex, laparoscopic procedure, BMI, history of nausea or motion sickness, and analgesic intake within 30 days, the receiver operating characteristic analysis revealed that the AUC values in the training and validation cohorts were 0.81 and 0.83, respectively.

IMPLICATIONS

Predictors for PONV in same-day surgery include female sex, nonsmoker, history of motion sickness or nausea, high BMI, surgical duration >1 hour, laparoscopic procedure, and preoperative analgesic intake within 30 days. A new predictive model is feasible for predicting the incidence of PONV based on the preoperative and intraoperative predictors.

Real-world data and evidence in pain research: a qualitative systematic review of methods in current practice

The use of routinely collected health data (real-world data, RWD) to generate real-world evidence (RWE) for research purposes is a growing field. Computerized search methods, large electronic databases, and the development of novel statistical methods allow for valid analysis of data outside its primary clinical purpose. Here, we systematically reviewed the methodology used for RWE studies in pain research. We searched 3 databases (PubMed, EMBASE, and Web of Science) for studies using retrospective data sources comparing multiple groups or treatments. The protocol was registered under the DOI:10.17605/OSF.IO/KGVRM. A total of 65 studies were included. Of those, only 4 compared pharmacological interventions, whereas 49 investigated differences in surgical procedures, with the remaining studying alternative or psychological interventions or epidemiological factors. Most 39 studies reported significant results in their primary comparison, and an additional 12 reported comparable effectiveness. Fifty-eight studies used propensity scores to account for group differences, 38 of them using 1:1 case:control matching. Only 17 of 65 studies provided sensitivity analyses to show robustness of their findings, and only 4 studies provided links to publicly accessible protocols. RWE is a relevant construct that can provide evidence complementary to randomized controlled trials (RCTs), especially in scenarios where RCTs are difficult to conduct. The high proportion of studies reporting significant differences between groups or comparable effectiveness could imply a relevant degree of publication bias. RWD provides a potentially important resource to expand high-quality evidence beyond clinical trials, but rigorous quality standards need to be set to maximize the validity of RWE studies.

Factors associated with unfavorable outcomes in patients with acute abdominal pain visiting the emergency department

BACKGROUND

Unfavorable outcomes occur in patients with acute abdominal pain who visit the emergency department (ED). We aimed to determine the factors associated with unfavorable outcomes in patients with acute abdominal pain visiting the ED.

METHODS

This retrospective cohort study was conducted from July 1, 2015 to June 30, 2016. The inclusion criterion was patients aged older than 18 years who presented to the ED with acute abdominal pain. Significant factors associated with unfavorable outcomes were examined using univariate and multivariate logistic regression analyses.

RESULTS

A total of 951 patients were included in the study. Multivariate logistic regression analysis showed that the ED length of stay (EDLOS) > 4 h (adjusted odds ratio (AOR) 2.62, 95% confidence interval [CI]: 1.33-5.14; p = 0.005), diastolic blood pressure (DBP) < 80 mmHg (AOR 3.31, 95% CI: 1.71-6.4; p ≤ 0.001), respiratory rate ≥ 24 breaths/min (AOR 2.03, 95% CI: 1.07-3.86; p ≤ 0.031), right lower quadrant (RLQ) tenderness (AOR 3.72, 95% CI: 1.89-7.32; p ≤ 0.001), abdominal distension (AOR 2.91, 95% CI: 1.29-6.57; p = 0.010), hypoactive bowel sounds (AOR 2.89, 95% CI: 1.09-7.67; p = 0.033), presence of specific abdominal signs (AOR 2.07, 95% CI: 1.1-3.88; p = 0.024), white blood cell count ≥ 12,000 cells/mm³ (AOR 2.37, 95% CI: 1.22-4.6; p = 0.011), and absolute neutrophil count (ANC) > 75% (AOR 2.83, 95% CI: 1.39-5.75; p = 0.004) were revealed as significant factors associated with unfavorable outcomes.

CONCLUSIONS

The present study revealed that the significant clinical signs associated with the occurrence of unfavorable outcomes were DBP < 80 mmHg, tachypnea (≥ 24 breaths/min), RLQ tenderness, abdominal distension, hypoactive bowel sounds, and presence of specific abdominal signs. Moreover, the associated laboratory results identified in this study were leukocytosis and ANC > 75%. Additionally, patients with abdominal pain visiting the ED who had an EDLOS longer than 4 h were associated with unfavorable outcomes.

Lessons from the Analysis of a Retrospective Cohort of Patients Who Underwent Large Open Abdominal Surgery Under Total Intravenous Opioid-Free Anesthesia

Background

Opioid-free anesthesia (OFA) is a new method of anesthesia based on a paradigm shift. Under general anesthesia, the physiology and/or the pathophysiological variations clinically observed are more a reflection of a systemic reaction to the stress (surgical and anesthesia stresses) than a true reflection of pain.

Objective

To report the results of a large monocenter, retrospective, non-interventional observational study of all consecutive patients who received a total intravenous (IV)-OFA protocol for the surgical management of major open abdominal and urological surgery.

Patients and Methods

We retrospectively extracted the anesthesia files of 311 consecutive patients (regional anesthesia excluded). No opioids were administered to any of these patients during the surgery. IV morphine administered in the recovery room was the primary endpoint of the study. The secondary endpoints included the amount of opioid required during the first two postoperative days, as well as the maximum pain intensity.

Results

Only very small doses of IV morphine were administered. The mean total morphine titration was 2 mg (1.9 ± 2.9 mg), corresponding to control of the maximal level of pain to 2.1 ± 2.6 as evaluated with a numerical scale in the postoperative care unit. Similarly, we observed a very low level of morphine consumption during the first two postoperative days.

Conclusions

These results highlight the safety and the feasibility of our total IV-OFA protocol, thus confirming this new paradigm. Under general anesthesia, the cardiovascular and inflammatory response to the stress could be reliably managed through a multimodal approach without a need for opioids. In the postoperative period, very low doses of opioids were required.

Electronic supplementary material

The online version of this article (10.1007/s40801-020-00218-3) contains supplementary material, which is available to authorized users.

Opioid free anesthesia: evidence for short and long-term outcome

The introduction of synthetic opioids in clinical practice played a major role in the history of anesthesiology. For years, anesthesiologists have been thinking that opioids are needed for intraoperative anesthesia. However, we now know that opioids (especially synthetic short-acting molecules) are definitely not ideal analgesics and may even be counterproductive, increasing postoperative pain. As well, opioids have revealed important drawbacks associated to poor perioperative outcomes. As a matter of fact, efforts in postoperative pain management in the last 30 years were driven by the idea of reducing/eliminating opioids from the postoperative period. However, a modern concept of anesthesia should eliminate opioids already intra-operatively towards a balanced, opioid-free approach (opioid-free anesthesia - OFA). In OFA drugs and techniques historically proven for their efficacy are combined in rational and defined protocols. They include ketamine, alpha-2 agonists, lidocaine, magnesium, anti-inflammatory drugs and regional anesthesia. Promising results have been obtained on perioperative outcome. For sure, analgesia is not reduced with OFA, but it is effective and with less opioid-related side effects. These benefits may be of particular importance in some high-risk patients, like OSAS, obese and chronic opioid-users/abusers. OFA may also increase patient-reported outcomes; despite it is difficult to specifically rule out the effect of intraoperative opioids. Finally, few data are available on long-term outcomes (persistent pain and opioid abuse, cancer outcome). New studies and data are required to elaborate the optimal approach for each patient/surgery, but interest and publication are increasing and may open the road to the wider adoption of OFA.