Remifentanil

Remifentanil stabilizes hemodynamics with modulating subthalamic beta oscillation during deep brain stimulation

General anesthesia is a promising method for advanced Parkinson's disease patients unable to tolerate awake deep brain stimulation (DBS) surgery. However, anesthetic agents must be kept at relatively low levels to preserve the quality of intraoperative microelectrode recordings, which can lead to unstable hemodynamic conditions. Remifentanil, with its sedative and analgesic properties, could offer a solution. This study retrospectively analyzed microelectrode recordings of the subthamic nucleus (STN) and hemodynamic responses in patients with Parkinson's disease who received deep brain stimulation surgery under controlled volatile anesthesia with/without remifentanil infusion. From October 2017 to June 2019, 24 patients with Parkinson's disease who received bilateral subthalamic deep brain stimulation surgery in Hualien Tzu Chi Hospital with (n = 12) or without remifentanil infusion (n = 12) were enrolled in this study. We conducted a comprehensive spike analysis, examining frequency, inter-spike interval properties, modified burst index, modified pause index, and modified pause ratio. Additionally, we performed spike frequency spectrum analysis to investigate oscillatory activity in high-frequency, multi-unit, and single-unit neuronal activity. Our findings revealed no differences in STN firing characteristics, while a significant decrease in high beta power was observed in multi-unit activity in the remifentanil group. Notably, nine patients in the non-remifentanil group required additional nicardipine, whereas none in the remifentanil group did. Conclusively, for patients with advanced Parkinson's disease sensitive to external stimulation at low minimum alveolar concentration, remifentanil co-administration is an option to avoid unstable hemodynamic conditions during subthalamic deep brain stimulation surgery.

Local Anesthesia and Enhanced Recovery after Transcarotid Artery Revascularization

BACKGROUND

Transcarotid artery revascularization (TCAR) is a minimally invasive surgical treatment for carotid artery stenosis. This study describes a 10-year institutional experience of TCAR and the concurrent development of enhanced recovery protocols.

METHODS

Standardized practices were implemented at a single institution for patients undergoing TCAR. This included protocolized preoperative imaging and medical optimization, intraoperative workflow, and postoperative care. Additionally, vascular anesthesiology protocols were established for managing local and general anesthesia. A retrospective review of patients undergoing TCAR was subsequently conducted. Data on patient demographics, procedural details, and outcomes were analyzed from a prospectively maintained institutional database.

RESULTS

Across 321 patients, the median hospital stay after TCAR was 1.0 days with low-postoperative complications, most notably a 1.9% perioperative stroke-death rate.

CONCLUSION

Multidisciplinary collaboration is necessary to develop sustainable and effective enhanced recovery protocols. Implementation of these care pathways can improve patient outcomes and efficiency of care.

Anesthetic Effect on the Subthalamic Nucleus in Microelectrode Recording and Local Field Potential of Parkinson's Disease

OBJECTIVES

Anesthetic agents used during deep brain stimulation (DBS) surgery might interfere with microelectrode recording (MER) and local field potential (LFP) and thus affect the accuracy of surgical target localization. This review aimed to identify the effects of different anesthetic agents on neuronal activity of the subthalamic nucleus (STN) during the MER procedure.

MATERIALS AND METHODS

We used Medical Subject Heading terms to search the PubMed, EMBASE, EBSCO, and ScienceDirect data bases. MER characteristics were sorted into quantitative and qualitative data types. Quantitative data included the burst index, pause index, firing rate (FR), and interspike interval. Qualitative data included background activity, burst discharge (BD), and anesthetic agent effect. We also categorized the reviewed manuscripts into those describing local anesthesia with sedation (LAWS) and those describing general anesthesia (GA) and compiled the effects of anesthetic agents on MER and LFP characteristics.

RESULTS

In total, 26 studies on MER were identified, of which 12 used LAWS and 14 used GA. Three studies on LFP also were identified. We found that the FR was preserved under LAWS but tended to be lower under GA, and BD was reduced in both groups. Individually, propofol enhanced BD but was better used for sedation, or the dosage should be minimized in GA. Similarly, low-dose dexmedetomidine sedation did not disturb MER. Opioids could be used as adjunctive anesthetic agents. Volatile anesthesia had the least adverse effect on MER under GA, with minimal alveolar concentration at 0.5. Dexmedetomidine anesthesia did not affect LFP, whereas propofol interfered with the power of LFP.

CONCLUSIONS

The effects of the tested anesthetics on the STN in MER and LFP of Parkinson's disease varied; however, identifying the STN and achieving a good clinical outcome are possible under controlled anesthetic conditions. For patient comfort, anesthesia should be considered in STN-DBS.

Comparison of postoperative awakening between ciprofol and propofol in elderly patients undergoing hip replacement surgery: a single-blind, randomized, controlled trial

BACKGROUND

The aim of this paper was to compare the impact of continuous infusion of ciprofol versus propofol on postoperative awakening in elderly patients following hip replacement surgery.

METHODS

Patients were randomized into two groups (N.=45 each): the ciprofol group and the propofol group. The ciprofol group received ciprofol for anesthesia induction and maintenance, while the propofol group underwent anesthesia induction and maintenance using propofol. The primary outcome was awakening time. Secondary outcomes included spontaneous breathing recovery time, extubation time, time to modified Aldrete Score ≥9, modified observer's assessment of alertness/sedation (MOAA/S) scores, anesthetic dosage, volume of fluid replacement, urine output and administration of vasoactive drugs.

RESULTS

The Ciprofol group exhibited a significantly prolonged awakening time (11.0±6.4 min vs. 7.4±4.3 min, P=0.003), spontaneous breathing recovery time (9.9±6.3 min vs. 5.9±4.3 min, P=0.001), and extubation time (12.0 [8.0-16.0] min vs. 8.5 [6.0-11.0] min, P=0.005), and reduced requirement for intraoperative fluid replacement (728.9±254.2 mL vs. 908.3±287.5 mL, P=0.003), increased urine output (235.1±102.1 mL vs. 173.5±106.2 mL, P=0.007), decreased likelihood of vasoactive drug administration (15/30 vs. 28/14, P=0.002). No significant differences were observed between the two groups in terms of reaching a modified Aldrete Score ≥9, MOAA/S scores at 0, 5, 15, or 30 minutes post-extubation, or occurrence of adverse reactions (P>0.05). The dosage of remifentanil was significantly higher in the ciprofol group [5.4 (2.7-7.4) μg·kg-1·h-1 vs. 3.4 (1.9-4.3) μg·kg-1·h-1, P=0.004], with a mean maintenance dose of ciprofol at 0.8 mg·kg-1·h-1 (range: 0.5 to 1.2 mg·kg-1·h-1).

CONCLUSIONS

Compared to propofol, the administration of ciprofol in elderly patients following hip replacement surgery is associated with prolonged awakening time, spontaneous breathing recovery time, and extubation. The average intravenous maintenance dosage of ciprofol in geriatric patients under general anesthesia was 0.8 mg·kg-1·h-1.

An automated dispensing cabinet alert influences anesthesia provider medication preparation in a remifentanil waste reduction initiative

STUDY OBJECTIVE

To decrease the occurrence of remifentanil waste of 1 mg or more (1 full vial) by 25 % in our surgical division while maintaining satisfaction of 60 % of providers by using a remifentanil mixing workflow.

DESIGN

A time series-design quality improvement initiative targeted preventable remifentanil waste. A period of active interventions, followed by a pause and reinstatement of a system intervention, was used to validate its effectiveness.

SETTING

An academic medical center in the US with 1219 inpatient beds, performing 144,418 surgical cases in 2019 and 127,341 surgical cases in 2020, in 148 operating rooms.

INTERVENTIONS

Individual- and system-level interventions provided education on the issues of preventable waste, access to a remifentanil dose calculator, and an automated dispensing cabinet (ADC) alert to halt wasteful practice.

MEASUREMENTS

Preventable remifentanil waste was identified as disposing of intravenous infusion bags containing 1 mg or more or 1 full vial or more of unused medication. Data were retrieved from ADC reports. A preimplementation and postimplementation survey of anesthesia providers assessed workflow attitudes, perceptions, and satisfaction surrounding remifentanil mixing.

MAIN RESULTS

Preventable remifentanil waste (≥1 mg or ≥ 1 full vial) decreased significantly from 22.0 % of cases using remifentanil at baseline to 16.7 % of cases using remifentanil (odds ratio, 0.71; 95 % CI, 0.60-0.84; P < .001) during the final data collection. Individual-level interventions of education, remifentanil dose calculator, and practice champions did not significantly affect waste while unpaired from the system intervention of the ADC alert.

CONCLUSIONS

The implementation of an ADC alert reduced preventable remifentanil waste among anesthesia providers.

A randomized controlled trial of propofol-remifentanil total intravenous anesthesia and sevoflurane-fentanyl anesthesia on early postoperative fatigue in patients undergoing laparoscopic colorectal surgery

PURPOSE

Even after uncomplicated surgery, postoperative fatigue prevalence has been reported to be 30-80% for various surgeries. We evaluated postoperative fatigue according to anesthetic technique in patients who underwent colorectal surgery.

METHODS

One hundred thirty patients who underwent colorectal surgery were randomly assigned to either propofol-remifentanil total intravenous anesthesia (propofol-remifentanil group, n = 65) or sevoflurane-fentanyl anesthesia (sevoflurane-fentanyl group, n = 65). The primary outcome was the prevalence of postoperative fatigue, as defined by the Chalder Fatigue Questionnaire (total score ≥ 16), at 24 h postoperatively. Secondary outcomes were early postoperative complications during hospitalization and laboratory examination.

RESULTS

The final analyses included 127 patients. The prevalence of postoperative fatigue on the 1st postoperative day was lower in the propofol-remifentanil group than the sevoflurane-fentanyl group: 56.3% (36/64) in the propofol-remifentanil group and 73.0% (46/63) in the sevoflurane-fentanyl group (relative risk [RR] = 0.77, 95% confidence interval [CI] 0.59-1.00; P = 0.048). However, there was no difference between the two groups in postoperative fatigue at postoperative day 3. Other postoperative outcomes including the severity of pain and the incidence of nausea/vomiting were not different between the two groups, but postoperative atelectasis on chest X-ray was higher in the sevoflurane-fentanyl group (2/64 [3.1%] vs. 9/63 [14.3%], P = 0.025). C-reactive protein change from preoperative to postoperative day 1 and 5 was significantly lower in the propofol-remifentanil group (P = 0.044).

CONCLUSION

Propofol-remifentanil total intravenous anesthesia was associated with reduced postoperative fatigue at the 1st postoperative day compared with sevoflurane-fentanyl anesthesia. Clinical trial The Korean Clinical Research Registry (study identifier: KCT0006917, principal investigator's name: MiHye Park, date of registration: January 12, 2022).

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.

The effects of the administration sequence and the type of hypnotics on the development of remifentanil-induced chest wall rigidity: a randomized controlled trial

BACKGROUND

Research on remifentanil-induced chest wall rigidity is limited. Furthermore, its incidence is unknown, and the clinical factors influencing its development remain unclear. This prospective, double-blind, randomized controlled trial aimed to investigate the effects of the administration sequence of hypnotics and remifentanil as well as the type of hypnotic administered on the development of remifentanil-induced chest wall rigidity.

METHODS

A total of 125 older patients aged [Formula: see text] 65 years, who were scheduled to undergo elective surgery under general anesthesia, were enrolled in this study. Participants were randomly assigned to one of four groups; Thio-Remi, Pro-Remi, Remi-Thio, or Remi-Pro. After confirming the loss of consciousness and achieving a target effect-site concentration of 3 ng/mL remifentanil, the development of remifentanil-induced chest wall rigidity was evaluated.

RESULTS

The incidence of chest wall rigidity was significantly higher in the remifentanil-hypnotic group than in the hypnotic-remifentanil (opposite sequence) group (55.0% vs. 21.7%, P < 0.001). Logistic regression analysis revealed that remifentanil-hypnotic administration was a significant predictor of the development of chest wall rigidity (crude odds ratio 4.42, 95% confidence interval 1.99; 9.81, P < 0.001).

CONCLUSIONS

Pretreatment with hypnotics potentially reduces the development of chest wall rigidity during the induction of balanced anesthesia with remifentanil in older patients.

TRIAL REGISTRATION

This article was registered at WHO International Clinical Trials Registry Platform (Trial number: KCT0006542).

A pharmacologically pre-contracted smooth muscle bowel model for the study of highly-potent opioid receptor agonists and antagonists

Isolated organ models are a versatile tool for pharmacological and toxicological research. Small bowel has been used to assess the inhibition of smooth muscle contraction by opioids. In the present study, we set out to establish a pharmacologically stimulated rat bowel model. The effects of carfentanil, remifentanil and the new synthetic opioid U-48800 and their respective antagonists naloxone, nalmefene and naltrexone were studied in a small bowel model in rats. The IC₅₀ values of the tested opioids were as follows: carfentanil (IC₅₀ = 0.02 µmol/L, CI 0.02-0.03 µmol/L) ≫ remifentanil (IC₅₀ = 0.51 µmol/L, CI 0.40-0.66 µmol/L) ≫ U-48800 (IC₅₀ = 1.36 µmol/L, CI 1.20-1.54 µmol/L). The administration of the opioid receptor antagonists naloxone, naltrexone and nalmefene led to progressive, parallel rightward shifts of the dose-response curves. Naltrexone was most potent in antagonizing the effects of U-48800, whereas naltrexone and nalmefene were most effective in antagonizing the effects of carfentanil. In summary, the current model seems to be a robust tool to study opioid effects in a small bowel model without the necessity of using electrical stimulation.

Distinct Profiles of Desensitization of µ-Opioid Receptors Caused by Remifentanil or Fentanyl: In Vitro Assay with Cells and Three-Dimensional Structural Analyses

Remifentanil (REM) and fentanyl (FEN) are commonly used analgesics that act by activating a µ-opioid receptor (MOR). Although optimal concentrations of REM can be easily maintained during surgery, it is sometimes switched to FEN for optimal pain regulation. However, standards for this switching protocol remain unclear. Opioid anesthetic efficacy is decided in part by MOR desensitization; thus, in this study, we investigated the desensitization profiles of REM and FEN to MOR. The efficacy and potency during the 1st administration of REM or FEN in activating the MOR were almost equal. Similarly, in β arrestin recruitment, which determines desensitization processes, they showed no significant differences. In contrast, the 2nd administration of FEN resulted in a stronger MOR desensitization potency than that of REM, whereas REM showed a higher internalization potency than FEN. These results suggest that different β arrestin-mediated signaling caused by FEN or REM led to their distinct desensitization and internalization processes. Our three-dimensional analysis, with in silico binding of REM and FEN to MOR models, highlighted that REM and FEN bound to similar but distinct sites of MOR and led to distinct β arrestin-mediated profiles, suggesting that distinct binding profiles to MOR may alter β arrestin activity, which accounts for MOR desensitization and internalization.

Effects of remifentanil on brain responses to noxious stimuli during deep propofol sedation

BACKGROUND

The safety of anaesthesia has improved as a result of better control of anaesthetic depth. However, conventional monitoring does not inform on the nature of nociceptive processes during unconsciousness. A means of inferring the quality of potentially painful experiences could derive from analysis of brain activity using neuroimaging. We have evaluated the dose effects of remifentanil on brain response to noxious stimuli during deep sedation and spontaneous breathing.

METHODS

Optimal data were obtained in 26 healthy subjects. Pressure stimulation that proved to be moderately painful before the experiment was applied to the thumbnail. Functional MRI was acquired in 4-min periods at low (0.5 ng ml^-1), medium (1 ng ml^-1), and high (1.5 ng ml^-1) target plasma concentrations of remifentanil at a stable background infusion of propofol adjusted to induce a state of light unconsciousness.

RESULTS

At low remifentanil doses, we observed partial activation in brain areas processing sensory-discriminative and emotional-affective aspects of pain. At medium doses, relevant changes were identified in structures highly sensitive to general brain arousal, including the brainstem, cerebellum, thalamus, auditory and visual cortices, and the frontal lobe. At high doses, no significant activation was observed.

CONCLUSIONS

The response to moderately intense focal pressure in pain-related brain networks is effectively eliminated with safe remifentanil doses. However, the safety margin in deep sedation-analgesia would be narrowed in minimising not only nociceptive responses, but also arousal-related biological stress.

Sufentanil target controlled infusion (TCI) versus remifentanil TCI for monitored anaesthesia care for patients with severe tracheal stenosis undergoing fiberoptic bronchoscopy: protocol for a prospective, randomised, controlled study

INTRODUCTION

The use of monitored anaesthesia care (MAC) is necessary and ubiquitous for fiberoptic bronchoscopy. Anaesthetic management of patients with severe tracheal stenosis has always been a challenge. The efficacy and safety of the MAC with sufentanil target controlled infusion (TCI) and remifentanil TCI in patients with severe tracheal stenosis are still unknown.

METHODS ANALYSIS

This study is a prospective, investigator-initiated, two-arm, randomised control trial to compare the efficacy and safety of sufentanil TCI with remifentanil TCI in patients with severe tracheal stenosis undergoing fiberoptic bronchoscopy. 270 patients will be randomly assigned to the sufentanil TCI group or remifentanil TCI group, with a 1:1 ratio in two groups. The primary outcome is the incidence of hypoxaemia (an oxygen saturation of <90%). The secondary outcome investigates the severity of hypoxaemia, cough severity, haemodynamic variables, sedation scores and satisfaction scores.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Ethics Committee of Shanghai Pulmonary Hospital (approval No. K19-122). The results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ChiCTR2100043380.

Structural Modification in Anesthetic Drug Development for Prodrugs and Soft Drugs

Among the advancements in drug structural modifications, the increased focus on drug metabolic and pharmacokinetic properties in the anesthetic drug design process has led to significant developments. Drug metabolism also plays a key role in optimizing the pharmacokinetics, pharmacodynamics, and safety of drug molecules. Thus, in the field of anesthesiology, the applications of pharmacokinetic strategies are discussed in the context of sedatives, analgesics, and muscle relaxants. In this review, we summarize two approaches for structural optimization to develop anesthetic drugs, by designing prodrugs and soft drugs. Drugs that both failed and succeeded during the developmental stage are highlighted to illustrate how drug metabolism and pharmacokinetic optimization strategies may help improve their physical and chemical properties.

Pre-procedural Preparation and Sedation for Gastrointestinal Endoscopy in Patients with Advanced Liver Disease

Gastrointestinal endoscopy in patients with advanced liver disease poses various challenges, a major one being procedural sedation and its associated considerations. While sedation during endoscopy can improve patient comfort, decrease anxiety, and facilitate procedural completion, in patients with advanced liver disease, it is also associated with substantial and unique risks due to alterations in drug metabolism and other factors. As such, the choice of sedative agent(s) and related logistics may require careful inter-disciplinary planning and individualized considerations. Furthermore, a large proportion of agents require dose reductions and particular monitoring of the vital signs, level of consciousness, and other indices. In the present review, we provide a contemporary overview of procedural sedation considerations, commonly used intravenous sedatives, and second-line as well as novel sedatives for gastrointestinal endoscopy in patients with advanced liver disease.

Global sensitivity analysis in physiologically-based pharmacokinetic/pharmacodynamic models of inhaled and opioids anesthetics and its application to generate virtual populations

The integration between physiologically-based pharmacokinetics (PBPK) models and pharmacodynamics (PD) models makes it possible to describe the absorption, distribution, metabolism and excretion processes of drugs, together with the concentration-response relationship, being a fundamental framework with wide applications in pharmacology. Nevertheless, the enormous complexity of PBPK models and the large number of parameters that define them leads to the need to study and understand how the uncertainty of the parameters affects the variability of the models output. To study this issue, this paper proposes a global sensitivity analysis (GSA) to identify the parameters that have the greatest influence on the response of the model. It has been selected as study cases the PBPK models of an inhaled anesthetic and an analgesic, along with two PD interaction models that describe two relevant clinical effects, hypnosis and analgesia during general anesthesia. The subset of the most relevant parameters found adequately with the GSA method has been optimized for the generation of a virtual population that represents the theoretical output variability of various model responses. The generated virtual population has the potential to be used for the design, development and evaluation of physiological closed-loop control systems.

Effect of GOAL-Directed ANalgesia using ANI (Analgesia/Nociception Index) during general anesthesia on immediate postoperative pain and intraoperative hemodynamics in adult patients (GOALDAN study): a study protocol for randomized, controlled, multicenter trial

Background

Severe postoperative pain remains a major problem that is seen in 20 to 40% of patients. The Analgesia/Nociception Index (ANI) is a 0–100 index reflecting the relative parasympathetic activity allowing for intraoperative analgesia monitoring. We have previously shown that an ANI value < 50 immediately before extubation may predict the occurrence of immediate postoperative pain with good performance. We hypothesized that GOAL-Directed ANalgesia may provide reduced immediate postoperative pain and optimized intraoperative remifentanil administration (GOLDAN study).

Methods

The GOALDAN study is an international, multicenter, simple-blind, parallel, prospective, randomized, controlled, two-armed trial. Patients are randomly assigned in a 1:1 ratio in the control group or in the experimental group. Patients will be randomly allocated to either the intervention group (ANI) or the control group (standard care only). In the ANI group, the administration of remifentanil will be goal-directed targeting a 50–80 ANI range, with a prophylactic injection of morphine immediately after extubation if the case of ANI < 50. Our primary objective was to determine whether the prophylactic administration of morphine at the end of the procedure in patients at risk of immediate postoperative pain (ANI < 50 immediately before extubation) could reduce the incidence of the latter by 50% in the post-anesthetic care unit. Our secondary objective was to determine whether the intraoperative use of goal-directed analgesia with an ANI target of 50 to 80 could improve intraoperative hemodynamics and postoperative outcome.

Discussion

Because of the paucity of well-conducted trials, the authors believe that a randomized-controlled trial will improve the evidence for using analgesia monitoring during general anesthesia and strengthen current recommendations for intraoperative analgesia management.

Trial registration

ClinicalTrials.gov NCT03618082. Registered on 7 August 2018

Brain-based measures of nociception during general anesthesia with remifentanil: A randomized controlled trial

BACKGROUND

Catheter radiofrequency (RF) ablation for cardiac arrhythmias is a painful procedure. Prior work using functional near-infrared spectroscopy (fNIRS) in patients under general anesthesia has indicated that ablation results in activity in pain-related cortical regions, presumably due to inadequate blockade of afferent nociceptors originating within the cardiac system. Having an objective brain-based measure for nociception and analgesia may in the future allow for enhanced analgesic control during surgical procedures. Hence, the primary aim of this study is to demonstrate that the administration of remifentanil, an opioid widely used during surgery, can attenuate the fNIRS cortical responses to cardiac ablation.

METHODS AND FINDINGS

We investigated the effects of continuous remifentanil on cortical hemodynamics during cardiac ablation under anesthesia. In a randomized, double-blinded, placebo (PL)-controlled trial, we examined 32 pediatric patients (mean age of 15.8 years,16 females) undergoing catheter ablation for cardiac arrhythmias at the Cardiology Department of Boston Children's Hospital from October 2016 to March 2020; 9 received 0.9% NaCl, 12 received low-dose (LD) remifentanil (0.25 mcg/kg/min), and 11 received high-dose (HD) remifentanil (0.5 mcg/kg/min). The hemodynamic changes of primary somatosensory and prefrontal cortices were recorded during surgery using a continuous wave fNIRS system. The primary outcome measures were the changes in oxyhemoglobin concentration (NadirHbO, i.e., lowest oxyhemoglobin concentration and PeakHbO, i.e., peak change and area under the curve) of medial frontopolar cortex (mFPC), lateral prefrontal cortex (lPFC) and primary somatosensory cortex (S1) to ablation in PL versus remifentanil groups. Secondary measures included the fNIRS response to an auditory control condition. The data analysis was performed on an intention-to-treat (ITT) basis. Remifentanil group (dosage subgroups combined) was compared with PL, and a post hoc analysis was performed to identify dose effects. There were no adverse events. The groups were comparable in age, sex, and number of ablations. Results comparing remifentanil versus PL show that PL group exhibit greater NadirHbO in inferior mFPC (mean difference (MD) = 1.229, 95% confidence interval [CI] = 0.334, 2.124, p < 0.001) and superior mFPC (MD = 1.206, 95% CI = 0.303, 2.109, p = 0.001) and greater PeakHbO in inferior mFPC (MD = -1.138, 95% CI = -2.062, -0.214, p = 0.002) and superior mFPC (MD = -0.999, 95% CI = -1.961, -0.036, p = 0.008) in response to ablation. S1 activation from ablation was greatest in PL, then LD, and HD groups, but failed to reach significance, whereas lPFC activation to ablation was similar in all groups. Ablation versus auditory stimuli resulted in higher PeakHbO in inferior mFPC (MD = 0.053, 95% CI = 0.004, 0.101, p = 0.004) and superior mFPC (MD = 0.052, 95% CI = 0.013, 0.091, p < 0.001) and higher NadirHbO in posterior superior S1 (Pos. SS1; MD = -0.342, 95% CI = -0.680, -0.004, p = 0.007) during ablation of all patients. Remifentanil group had smaller NadirHbO in inferior mFPC (MD = 0.098, 95% CI = 0.009, 0.130, p = 0.003) and superior mFPC (MD = 0.096, 95% CI = 0.008, 0.116, p = 0.003) and smaller PeakHbO in superior mFPC (MD = -0.092, 95% CI = -0.680, -0.004, p = 0.007) during both the stimuli. Study limitations were small sample size, motion from surgery, indirect measure of nociception, and shallow penetration depth of fNIRS only allowing access to superficial cortical layers.

CONCLUSIONS

We observed cortical activity related to nociception during cardiac ablation under general anesthesia with remifentanil. It highlights the potential of fNIRS to provide an objective pain measure in unconscious patients, where cortical-based measures may be more accurate than current evaluation methods. Future research may expand on this application to produce a real-time indication of pain that will aid clinicians in providing immediate and adequate pain treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02703090.

Aspiration pneumonia and anesthesia techniques in hip fracture surgery in elderly patients: A retrospective cohort study using administrative data

Purpose: Aspiration pneumonia is a critical issue. General anesthesia may suppress the airway's protective reflex. However, aspiration pneumonia is also observed in patients who undergo hip fracture surgery under spinal anesthesia. The aim of this study was to investigate the relationship between anesthesia methods and aspiration pneumonia as well as the predictive factors of aspiration pneumonia in elderly patients undergoing hip fracture surgery. Methods: The medical records of 19,809 patients aged ≥60 years who underwent hip fracture surgery under general or spinal anesthesia were reviewed. After propensity score matching, the anesthesia methods affecting the occurrences of aspiration pneumonia and other complications were investigated via logistic regression and instrumental variable analyses. Predictive factors of aspiration pneumonia were also investigated in all subjects using a multivariable logistic regression analysis. Results: Among the 11,673 general anesthesia patients and 8136 spinal anesthesia patients, aspiration pneumonia occurred in 356 patients (1.8%). Post-propensity score matching the incidences of aspiration pneumonia with general and spinal anesthesia were 1.8% and 1.5%, respectively (p = 0.158); other pulmonary complications were 1.5% and 1.5%, respectively (p = 0.893); and the mortality rates were 1.4% and 1.2%, respectively (p = 0.219). The predictive factors of aspiration pneumonia were advanced age, male sex, lean body, cerebrovascular disease, dementia, and dependency for activities of daily living (eating). Conclusion: Spinal and general anesthesia showed similar incidences of aspiration pneumonia in elderly hip fracture surgery. Regardless of the anesthesia method, great care should be taken, especially in elderly patients with the identified predictive factors.

Synthetic opioids: a review and clinical update

The term 'opioids' refers to both the natural compounds ('opiates') which are extracted from the opium poppy plant (Papaver somniferum) and their semi-synthetic and synthetic derivatives. They all possess relatively similar biochemical profiles and interact with the opioid receptors within the human body to produce a wide range of physiological effects. They have historically been used for medicinal purposes, their analgesic and sedative effects, and in the management of chronic and severe pain. They have also been used for non-medicinal and recreational purposes to produce feelings of relaxation, euphoria and well-being. Over the last decade, the emergence of an illegal market in new synthetic opioids has become a major global public health issue, associated with a substantial increase in unintentional overdoses and drug-related deaths. Synthetic opioids include fentanyl, its analogues and emerging non-fentanyl opioids. Their popularity relates to changes in criminal markets, pricing, potency, availability compared to classic opioids, ease of transport and use, rapid effect and lack of detection by conventional testing technologies. This article expands on our previous review on new psychoactive substances. We now provide a more in-depth review on synthetic opioids and explore the current challenges faced by people who use drugs, healthcare professionals, and global public health systems.

Impact of intraoperative intravenous magnesium on spine surgery: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The effectiveness and safety of intraoperative intravenous magnesium (IIM) on spine surgery remain uncertain, as recent randomized controlled trials (RCTs) yielded conflicting results. The purpose of this study was to determine the impact of IIM on spine surgery.

METHODS

A literature search was performed on multiple electronic databases, ClinicalTrial.gov and Google Scholar on July 12th 2021, and reference lists were examined. We selected RCTs comparing the effects of IIM with placebo treatment on spine surgery. We calculated pooled standard mean difference (SMD) or risk ratio (RR) with 95% confident interval (CI) under a random-effect model. We assessed risk of bias using Cochrane risk-of-bias tool and Jadad score was applied to assess the quality of each included trial. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to determine the confidence in effect estimates. Sensitivity analysis was conducted by omitting each included study one by one from the pooled analysis. PROSPERO Registration: CRD42021266170.

FINDINGS

Fourteen trials of 781 participants were included. Low- to moderate-quality evidence suggested that IIM reduces postoperative morphine consumption at 24 h (SMD: -1·61 mg, 95% CI: -2·63 to -0·58) and intraoperative remifentanil requirement (SMD: -2·09 ug/h, 95% CI: -3·38 to -0·81). High-quality evidence suggested that IIM reduces the risk of postoperative nausea and vomiting compared with placebo (RR: 0·43, 95% CI: 0·26 to 0·71). Besides, moderate-quality evidence suggested that recovery orientation time in the IIM group is longer than control group (SMD: 1·13 min, 95% CI: 0·83 to 1·43).

INTERPRETATION

IIM as adjuvant analgesics showed overall benefits on spine surgery in terms of reducing analgesic requirement and postoperative nausea and vomiting; however, potential risks of IIM, such as delayed anesthetic awakening, should not be ignored. Future evidence will inform the optimal strategy of IIM administration for patients undergoing spine surgery.

FUNDING

This study was funded by Beijing Municipal Natural Science Foundation (Grant No :7212117).

Opioid-induced analgesia among persons with opioid use disorder receiving methadone or buprenorphine: A systematic review of experimental pain studies

BACKGROUND

Treating acute pain among persons with opioid use disorder (OUD) on opioid agonist therapy (OAT) is complex, and the therapeutic benefits of opioids remain unclear when weighted against their abuse potential and respiratory depressant effects.

METHODS

We conducted a systematic review of experimental pain studies examining opioid-induced analgesia among persons with OUD on OAT. We searched multiple databases from inception to July 30, 2021. Study quality was assessed by previously established validity measures.

RESULTS

Nine studies were identified, with a total of 225 participants, of whom 63% were male, and 37% were female. Six studies included methadone-maintained persons with OUD; four studies included buprenorphine-maintained persons with OUD; and three studies included healthy persons as comparison groups. Either additional doses of OAT or other opioids - morphine, oxycodone, hydromorphone, or remifentanil - were administered. In seven studies, persons with OUD on OAT did not experience analgesia, despite receiving opioid doses up to 20 times greater than those clinically used to treat severe pain among the opioid naïve. Conversely, in two studies, high-potency opioids did produce analgesia, albeit with greater abuse potential. Notably, persons with OUD on OAT remained vulnerable to respiratory depression.

CONCLUSIONS

Although persons with OUD on OAT can derive analgesic effects from opioids, high-potency compounds may be required to achieve clinically significant pain relief. Further, persons with OUD on OAT may remain vulnerable to opioid-induced abuse potential and respiratory depression. Together, these finding have clinical, methodological, and mechanistic implications for the treatment of acute pain in the context of OAT.

The effects of chronic estradiol treatment on opioid self-administration in intact female rats

Heroin intake decreases significantly during proestrus in normally cycling female rats, and this effect is mediated by endogenous estradiol but not endogenous progesterone. The purpose of this study was to determine whether chronic administration of exogenous estradiol decreases intake of the semi-synthetic opioid, heroin, and the fully synthetic opioid, remifentanil, in intact female rats. Normally cycling female rats were implanted with intravenous catheters and trained to self-administer heroin on a fixed ratio (FR1) schedule of reinforcement. Rats were treated chronically with daily administration of either a low dose of estradiol (0.5 mcg, sc), a high dose of estradiol (5.0 mcg, sc), or vehicle (peanut oil, sc). After two weeks of heroin self-administration training, dose-effect curves were determined for both heroin and remifentanil. Chronic administration of estradiol non-significantly decreased heroin intake and significantly decreased remifentanil intake. Estradiol-induced decreases in remifentanil intake were dose-dependent, characterized by large effect sizes, and greatest in rats treated with the high dose of estradiol. These data indicate that chronic estradiol administration decreases opioid intake in intact female rats with medium to large effect sizes across opioids. These findings suggest that estrogen-based pharmacotherapies may represent a novel treatment approach for women with opioid use disorder.

Remifentanil up-regulates HIF1α expression to ameliorate hepatic ischaemia/reperfusion injury via the ZEB1/LIF axis

Ischaemia/reperfusion (I/R)-induced hepatic injury is regarded as a main reason of hepatic failure after transplantation or lobectomy. The current study aimed to investigate how the opioid analgesic remifentanil treatment affects I/R-induced hepatic injury and explore the possible mechanisms related to HIF1α. Initially, an I/R-induced hepatic injury animal model was established in C57BL/6 mice, and an in vitro hypoxia-reoxygenation model was constructed in NCTC-1469 cells, followed by remifentanil treatment and HIF1α silencing treatment. The levels of blood glucose, lipids, alanine transaminase (ALT) and aspartate transaminase (AST) in mouse serum were measured using automatic chemistry analyser, while the viability and apoptosis of cells were detected using CCK8 assay and flow cytometry. Our results revealed that mice with I/R-induced hepatic injury showed higher serum levels of blood glucose, lipids, ALT and AST and leukaemia inhibitory factor (LIF) expression, and lower HIF1α and ZEB1 expression (P < .05), which were reversed after remifentanil treatment (P < .05). Besides, HIF1α silencing increased the serum levels of blood glucose, lipids, ALT and AST (P < .05). Furthermore, hypoxia-induced NCTC-1469 cells exhibited decreased HIF1α and ZEB1 expression, reduced cell viability, as well as increased LIF expression and cell apoptosis (P < .05), which were reversed by remifentanil treatment (P < .05). Moreover, HIF1α silencing down-regulated ZEB1 expression, decreased cell viability, and increased cell apoptosis (P < .05). ZEB1 was identified to bind to the promoter region of LIF and inhibit its expression. In summary, remifentanil protects against hepatic I/R injury through HIF1α and downstream effectors.

Total Intravenous Anesthesia in Joubert Syndrome Patient for Otorhinolaryngology Surgery: A Case Report and Mini Review of the Literature

BACKGROUND Joubert syndrome is a rare autosomal recessive disorder first described in 1969, with an estimated prevalence of 1 in 100 000. Joubert syndrome is characterized by partial or complete agenesis of the cerebellar vermis - the structure that connects both parts of the cerebellum. This results in the main clinical symptoms, such as muscular hypotonia, ataxia, mental retardation, abnormal eye movements, and a central apnea breathing pattern. Joubert syndrome can combine neurological signs with variable multi-organ involvement, mainly of the retina, kidneys, liver, and musculoskeletal system. CASE REPORT A 13-year-old boy presenting with recurrent otitis media, fever, respiratory infections, and tonsillar hyperplasia needed surgery. At the otorhinolaryngology outpatient clinic, the indication for surgical paracentesis, adenoidectomy, and tonsillectomy under general anesthesia (first in his life) was set. We performed a total intravenous anesthesia (TIVA) using propofol (described as safe) and remifentanil (organ-independent metabolism) without any side-effects. For postoperative pain therapy we used metamizole instead of paracetamol in order to avoid liver injury. CONCLUSIONS Due to the possible facial dysmorphism we recommend a critical evaluation of the airway to assess a potential difficult airway preoperatively. Our case underlines that TIVA, with the medications used in this case, is safe. We refrained from premedication in order not to trigger central apnea. For safety reasons, all preparatory procedures were carried out in the recovery room under monitor surveillance and with audio-visual distraction for the patient in order to reduce the stress level. For postoperative pain therapy, we recommend the use of metamizole.

Do All Opioid Drugs Share the Same Immunomodulatory Properties? A Review From Animal and Human Studies

Suppression of the immune system has been constantly reported in the last years as a classical side effect of opioid drugs. Most of the studies on the immunological properties of opioids refer to morphine. Although morphine remains the "reference molecule," other semisynthetic and synthetic opioids are frequently used in the clinical practice. The primary objective of this review is to analyze the available literature on the immunomodulating properties of opioid drugs different from morphine in preclinical models and in the human. A search strategy was conducted in PubMed, Embase, and the Cochrane databases using the terms "immunosuppression," "immune system," "opioids," "Natural killer cells," "cytokines," and "lymphocytes." The results achieved concerning the effects of fentanyl, methadone, oxycodone, buprenorphine, remifentanil, tramadol, and tapentadol on immune responses in animal studies, in healthy volunteers and in patients are reported. With some limitations due to the different methods used to measure immune system parameters, the large range of opioid doses and the relatively scarce number of participants in the available studies, we conclude that it is not correct to generalize immunosuppression as a common side effect of all opioid molecules.

Opioids in the immune system: from experimental studies to clinical practice

INTRODUCTION

Opioids interact with both innate and adaptive immune systems and have direct effects on opioid receptors located on immune cells. Research on this topic has provided evidence of the opioid influence on the immune response associated with surgical stress. The immunological effects of opioids are currently being investigated, particularly whether they influence the outcome of surgery or the underlying disease regarding important aspects like infection or cancer progression. This review addresses background research related to the influence of the opioid receptor on the immune system, the immunosuppressive effect associated with major opioids during the perioperative period, and their clinical relevance. The objective of the study was to review the effects of opioids on the immune system.

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.

Comparison of dexmedetomidine vs. remifentanil combined with sevoflurane during radiofrequency ablation of hepatocellular carcinoma: a randomized controlled trial

BACKGROUND

Remifentanil is widely used for ultrasound-guided percutaneous radiofrequency ablation (RFA) of small hepatocellular carcinoma (HCC). We determined whether dexmedetomidine could be an alternative to remifentanil for RFA of HCC under general anesthesia with sevoflurane.

METHODS

We prospectively randomized patients scheduled to undergo RFA for HCC to a dexmedetomidine (DEX) group or remifentanil (REMI) group (47 patients each). In the DEX group, a bolus infusion (0.4 μg kg^- 1) was started 15 min before anesthesia induction and continued at 0.2 μg kg^- 1 h^- 1 until 10 min before the end of surgery. In the REMI group, 3 μg kg^- 1 h^- 1 of remifentanil was administered from 15 min before anesthesia induction to the end of the surgery. The primary endpoint was postoperative pain intensity. Secondary endpoints included analgesic requirement, postoperative liver function, patient comfort, and hemodynamic changes. Group allocation was concealed from patients and data analysts but not from anesthesiologists.

RESULTS

Postoperative pain intensity, analgesic consumption, comfort, liver function, and time to emergence and extubation did not differ between the two groups. Heart rate, but not mean arterial pressure, was significantly lower in the DEX group than in the REMI group, at 1 min after intubation and from 30 min after the start of the surgery until anesthesia recovery. Sevoflurane concentration and dosage were significantly lower in the DEX group than in the REMI group.

CONCLUSION

During RFA for HCC, low-dose dexmedetomidine reduced the heart rate and need for inhalational anesthetics, without exacerbating postoperative discomfort or liver dysfunction. Although it did not exhibit outstanding advantages over remifentanil in terms of pain management, dexmedetomidine could be a safe alternative adjuvant for RFA under sevoflurane anesthesia.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-OPC-15006613 . Registered on 16 June 2015.

A comparison of risk of hypotension using standard doses of remifentanil versus dexmedetomidine infusions in adult patients undergoing surgery under general anaesthesia at the Aga Khan University Hospital, Nairobi

Background

Remifentanil and dexmedetomidine are common agents used in general anaesthesia, monitored anaesthesia care and critical care. When combined with inhaled or intravenous anaesthetic agents intra-operatively, they provide analgesia, lower general anaesthetic requirements and provide sedation and analgesia in the peri-operative period if indicated. Pharmacodynamically, they cause hypotension and bradycardia which are reversible if well managed. Past studies of these drugs have shown a significant proportion of patients with hypotension when compared with similar agents or in isolation. This study compares these two drugs on the effect of hypotension when used as adjuncts to general anaesthesia at low dose standard rate of infusions.

Objective

To compare the proportion of hypotension episodes in a group of adult patients receiving dexmedetomidine infusion at 0.4mcg/kg/hr versus a group receiving remifentanil infusion at 0.2mcg/kg/min, severity of hypotension and physician interventions in each group.

Methods

One hundred and four patients scheduled for elective surgery under general anaesthesia were randomized into two groups: Control group; received remifentanil infusion at 0.2mcg/kg/min

Intervention group; received dexmedetomidine at 0.4mcg/kg/hr.

General anaesthesia was standardized in both groups. The patients were blinded to the study. Baseline blood pressures of all patients were determined prior to induction. The patient's demographic characteristics were recorded. The number of patients who developed hypotension, the frequency of hypotension and the physician interventions were recorded and analysed.

Results

The age and gender characteristics were different between the two groups (p values <0.023 and 0.05 respectively) however they did not affect the proportion of patients with hypotension. The weight, baseline pressures and ASA status of the patients within the groups were similar. The operative procedures varied within the groups. General surgery did not influence the outcome of hypotension in both arms. The duration of surgery in remifentanil group exceeded that of Dexmedetomidine p value<0.0005 however the time to the first episode of hypotension was similar between the groups. The episodes of hypotension were fewer in the dexmedetomidine arm and the proportion of patients with hypotension were higher in the remifentanil arm, p value<0.001, R.R 0. = 0.5938, 95% C.I= 0.329–0.819 The physician interventions administered were similar between the two groups except the use of ephedrine between the groups.

Conclusion

Among this population, at standard infusion rates, the proportion of patients that risk hypotension was greater in those undergoing elective surgery receiving remifentanil at 0.2mcg/kg/min than in dexmedetomidine at 0.4mcg/kg/hr under isoflurane based anaesthesia.

Effect of remifentanil on pre-osteoclast cell differentiation in vitro

BACKGROUND

The structure and function of bone tissue is maintained through a constant remodeling process, which is maintained by the balance between osteoblasts and osteoclasts. The failure of bone remodeling can lead to pathological conditions of bone structure and function. Remifentanil is currently used as a narcotic analgesic agent in general anesthesia and sedation. However, the effect of remifentanil on osteoclasts has not been studied. Therefore, we investigated the effect of remifentanil on pre-osteoclast (pre-OCs) differentiation and the mechanism of osteoclast differentiation in the absence of specific stimulus.

METHODS

Pre-OCs were obtained by culturing bone marrow-derived macrophages (BMMs) in osteoclastogenic medium for 2 days and then treated with various concentration of remifentanil. The mRNA expression of NFATc1 and c-fos was examined by using real-time PCR. We also examined the effect of remifentanil on the osteoclast-specific genes TRAP, cathepsin K, calcitonin receptor, and DC-STAMP. Finally, we examined the influence of remifentanil on the migration of pre-OCs by using the Boyden chamber assay.

RESULTS

Remifentanil increased pre-OC differentiation and osteoclast size, but did not affect the mRNA expression of NFATc1 and c-fos or significantly affect the expression of TRAP, cathepsin K, calcitonin receptor, and DC-STAMP. However, remifentanil increased the migration of pre-OCs.

CONCLUSIONS

This study suggested that remifentanil promotes the differentiation of pre-OCs and induces maturation, such as increasing osteoclast size. In addition, the increase in osteoclast size was mediated by the enhancement of pre-OC migration and cell fusion.

Effects of different doses of remifentanil on hemodynamic response to anesthesia induction in healthy elderly patients

OBJECTIVE

We compared the effects of three different doses of remifentanil infusion, which were performed for the induction of anesthesia in elder patients, on cardiovascular response.

RESEARCH DESIGN AND METHODS

The present study was designed as a randomized, prospective and double-blind study. A total of 90 ASA I-II patients over the age of 65 years were enrolled. The patients were randomly (by lot) assigned to receive one of the three doses of remifentanil infusion (0.1, 0.2 or 0.3 μg/kg/min) for two minutes. Subsequently, 0.5 mg/kg propofol was administered via IV route and 0.5 mg/kg rocuronium was administered via IV route at the time eyelash reflex disappeared. Intubation was performed after 2 minutes. Patients who had an allergy against opioids, were chronic substance users, were obese, expected to have difficult airway, had hypertension, or were receiving any drug influencing the cardiovascular system were excluded.

MAIN OUTCOME MEASURES

In this study after recording baseline values of heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP), these values were recorded at the 1st, 2nd, 3rd, 4th and 5th minutes of induction.

RESULTS

A significant increase was observed in heart rate at the 1st and 2nd minutes of induction versus baseline in the Remi 0.1 group and at the 2nd minute of induction versus baseline in the Remi 0.2 group, with no additional significant change in heart rate. A significant decrease was determined in the systolic, diastolic and mean arterial pressures in all groups from the 1st minute of induction of anesthesia to the pre-intubation period compared to baseline (p < .05).

CONCLUSIONS

It was determined that each dose of remifentanil used was quite high for patients of this age-group. ClinicalTrials.gov trial number: NCT02763098.

Propofol versus sevoflurane: Bleeding in endoscopic sinus surgery

OBJECTIVE: Reduction of intraoperative bleeding is desirable to improve intraoperative visibility and to avoid complications.

STUDY DESIGN: Prospective, controlled, randomized, double-blinded study.

SETTING: Inclusion criteria were chronic rhinosinusitis with nasal polyps that involved all paranasal sinuses, Lund-CT score ≤ 12, and double-blind preoperative randomization of narcotics. Exclusion criteria included abnormal coagulation, perioperative blood pressure outside the range of 70 to 140 mmHg systolic and 50 to 90 mmHg diastolic and perioperative medication. Total blood loss (mL), blood loss per minute (mL/min), platelet function, and parameter for endoscopic vision were evaluated.

RESULTS: Forty-six patients (22 sedated with sevoflurane/fentanyl, 24 sedated with propofol/fentanyl) completed the study. Total blood loss (300.1 ± 168.5 mL/276.9 ± 201.3 mL), blood loss per minute, and endoscopic vision showed no group difference. Platelet function was significantly impaired 45 minutes after onset of surgery in both groups, but more pronounced after propofol anesthesia.

CONCLUSION: Under conditions of balanced circulatory parameter, equal blood loss and endoscopic vision can be achieved with both tested anesthetic regimens. During extended operations demonstrated thrombocyte impairment by propofol may become clinically relevant.

© 2007 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved.

The influence of propofol and sevoflurane on intestinal motility during laparoscopic surgery

BACKGROUND

Volatile anaesthetics have an influence on small bowel peristalsis during laparoscopic surgery. A recent study concluded that desflurane increased intestinal motility compared to sevoflurane. Hence, a desflurane-based anaesthesia protocol may reduce surgical exposure during intestinal suturing or stapling due to small bowel hyperperistalsis. The effect of propofol on intestinal motility is not well studied. We tested the hypothesis that a propofol-remifentanil anaesthesia increases intestinal contractions in comparison with a sevoflurane-remifentanil anaesthesia.

METHODS

Patients scheduled for laparoscopic gastric bypass surgery were randomized in this single blind randomized controlled trial to receive remifentanil combined with sevoflurane or propofol (ISRCTN 12921661). Bispectral index monitoring was used to guide depth of anaesthesia. Visual observation of peristaltic waves was performed during 1 min at the planned site of the jejunostomy. Statistical analysis was performed using Wilcoxon two-sample test.

RESULTS

After obtaining written informed consent 50 patients were included. Groups were similar for demographic variables, and depth of anaesthesia during the observations. The median number of peristaltic waves was lower in the sevoflurane-remifentanil group compared to the propofol-remifentanil group (0 vs. 6, P < 0.001).

CONCLUSION

Propofol-remifentanil increases intestinal motility compared with sevoflurane-remifentanil during laparoscopic gastric bypass surgery. A sevoflurane-based protocol can help to avoid disturbing peristalsis.

Randomized double-blind comparison of remifentanil and alfentanil in patients undergoing laparoscopic cholecystectomy using total intravenous anesthesia

BACKGROUND AND AIMS

To compare the use of remifentanil and alfentanil to suppress intraoperative adrenergic response of pain and the influence of these drugs on the recovery profile in patients undergoing laparoscopic cholecystectomy using a total intravenous anesthesia (TIVA) technique.

MATERIAL AND METHODS

One hundred patients undergoing elective laparoscopic cholecystectomy were randomized to be managed with either remifentanil (group R) or alfentanil (group A). During general anesthesia, we evaluated adrenergic responses to intubation to first surgical incision and over the surgical procedure. We also recorded time to first spontaneous breathing, time to successful ventilation, time to respond to verbal orders, and time to extubation.

RESULTS

The R group reported a significantly lower number of responses to intubation and responses to first surgical incision (14% vs. 30%; P = 0.013 and 8% vs. 18%; P = 0,037, respectively). The event of one or more responses during the surgical procedure was also lower in the R group (56% vs. 70%; P = 0.017). Hypertensive response to surgical stimuli during the procedure was lower in the R group as well as a lower frequency of tachycardia episodes in this group (34% vs. 56%; P = 0.033 and 28% vs. 44%; P = 0.041, respectively). No differences were found between groups relating to the percentage of hypotensive episodes and no episodes of bradycardia were appreciated. Both groups were similar relating to recovery times: time to the first spontaneous breathing, time to successful ventilation, time to respond to verbal orders, and time to extubation.

CONCLUSION

Remifentanil showed a more stable hemodynamic response during the surgery compared with the use of alfentanil in anesthetized patients undergoing laparoscopic cholecystectomy using TIVA. Both opioids, alfentanil and remifentanil, have a similar recovery profile, and they do not delay time to awakening.

Successful intubation of a difficult airway due to a large obstructive vocal cord polyp augmented by the delivery of a transtracheal injection of local anaesthetic

We describe a case of a very difficult intubation which was safely navigated through careful planning. Our patient presented initially with increasing hoarseness and shortness of breath over a 6-month period. This was investigated and the patient was found to have a large vocal cord mass and was referred for urgent microlaryngoscopy and vocal cord polypectomy. On the day of surgery the obstruction was noted and awake fiberoptic bronchoscopy was used with a remifentanil infusion. Given the mass was large and increased in size with expiration, the time frame to pass the tube was extremely short. We delivered a transtracheal injection of local anaesthesia. This approach allowed for safe passage of the endotracheal tube. In patients such as this it may be worth considering the use of a transtracheal injection in the first instance.

Infraorbital and infratrochlear nerve blocks combined with general anaesthesia for outpatient rhinoseptoplasty: A prospective randomised, double-blind, placebo-controlled study

INTRODUCTION

We conducted a study to determine the efficacy of bilateral extraoral infraorbital and infratrochlear nerve blocks during outpatient rhinoseptoplasty under general anaesthesia.

PATIENTS AND METHODS

In this prospective, double-blind, randomised, controlled trial, 40 adult patients undergoing outpatient rhinoseptoplasty under general anaesthesia were assigned to receive bilateral infraorbital and infratrochlear nerve blocks with either 10mL of 0.25% levobupivacaine (Group LB) or isotonic saline (control group). Patients in Group LB received 0.1mL/kg of isotonic saline as a placebo and patients in the control group received 0.1mL/kg of morphine. The primary endpoint was total perioperative morphine consumption (intraoperative and in the post-anaesthesia care unit). The secondary endpoints were pain scores, time spent in the post-anaesthesia care unit and the outpatient ward, block-related complications and patient satisfaction.

RESULTS

The total dose of perioperative morphine was lower in Group LB than in the control group (2.5±2.8mg versus 9.5±3.5mg, respectively, P<0.001). The mean±SD or median [IQR] times spent in the post-anaesthesia care unit (60±10min and 78±33min, respectively, P<0.03) and in the outpatient ward (210 [178-223] min versus 275 [250-300] min, respectively, P<0.001) were lower in Group LB than in the control group. There were no differences between groups for other endpoints.

CONCLUSION

Bilateral extraoral infraorbital and infratrochlear nerve blocks performed with 0.25% levobupivacaine during general anaesthesia combining remifentanil and desflurane reduce the perioperative dose of morphine and the time spent in the post-anaesthesia care unit and the outpatient ward in adult patients undergoing outpatient rhinoseptoplasty.

Neuron-restrictive silencer factor in periaqueductal gray contributes to remifentanil-induced postoperative hyperalgesia via repression of the mu-opioid receptor

BACKGROUND

The ultra-short-acting mu-opioid receptor (MOR) agonist remifentanil induces postoperative hyperalgesia both in preclinical and clinical research studies. However, the precise mechanisms remain unclear, although changes in opioid receptor expression might be a correlative feature. Neuron-restrictive silencer factor (NRSF) functions as a crucial regulator of MOR expression in specific neuronal cells. Using a mouse model of incisional postoperative pain, we assessed the expression of MOR and NRSF and investigated whether disruption of NRSF expression could prevent the postoperative nociceptive sensitization induced by surgical incision and subcutaneous infusion of remifentanil.

METHODS

Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were independently used to assess mechanical allodynia and thermal hyperalgesia after surgery and cerebral ventricle injection of NRSF antisense oligonucleotide. Western blotting analyses were preformed to assess the expression levels of MOR and NRSF.

RESULTS

NRSF expression levels were enhanced after intraoperative infusion of remifentanil, resulting in repression of MOR expression in the periaqueductal gray (PAG). NRSF blockade with an NRSF antisense oligonucleotide significantly enhanced the expression levels of MOR and alleviated mechanical allodynia and thermal hyperalgesia induced by intraoperative infusion of remifentanil.

CONCLUSION

NRSF functions as a negative regulator of MOR in PAG and contributes to remifentanil-induced postoperative hyperalgesia. NRSF in PAG may be a potential target for this pain therapy.

Remifentanil, fentanyl, or the combination in surgical procedures in the United States: predictors of use in patients with organ impairment or obesity

INTRODUCTION

Remifentanil has a rapid onset and short duration of action, predictable pharmacokinetic/pharmacodynamic profile, and unlike fentanyl, does not accumulate with repeated or prolonged administration. This study evaluated predictors of remifentanil use in surgical patients with renal or hepatic impairment, or obesity in the United States who received remifentanil, fentanyl, or the combination.

METHODS

Data (2010) from the US Healthcare National Inpatient Database, State Inpatient Database, State Ambulatory Surgery Database, and private hospital and Medicaid databases were used in this analysis. Patients included had presence of hepatic or renal disease, and/or obesity and were >5 and ≤80 years of age.

RESULTS

In 2010, 9,274 patients with renal impairment, 1,896 with hepatic impairment, and 6,278 with obesity were identified. The percentage of surgical patients diagnosed with renal disease, hepatic disease, or obesity who received remifentanil was 41, 28, and 35%, respectively; 29, 17, and 22% received both remifentanil and fentanyl, and 30, 55, and 43% received fentanyl alone, respectively. In patients with renal or hepatic disease the probability of remifentanil use was greater for persons aged >50 years, with Medicare as primary payer, or who were diagnosed with obesity (p < 0.05 all comparisons). In obese patients, the probability of remifentanil use was greater for persons aged >50 years or female (both p < 0.05). For all 3 disease states, the probability of remifentanil use was lower for those receiving epidural anesthesia or with Medicaid as primary payer (p < 0.05 all comparisons).

CONCLUSION

Remifentanil in combination with fentanyl is used less than fentanyl in surgical patients with hepatic impairment or obesity. This is inconsistent with the fact that the pharmacokinetic/pharmacodynamic features of remifentanil suggest it is the preferred intraoperative opioid in these patients. Predictors of remifentanil use in patients with renal or hepatic impairment, or obesity include older age, obesity, and Medicare as primary payer. Remifentanil in combination with fentanyl was significantly less utilized than fentanyl in persons with Medicaid as primary payer even though there was a disproportionate enrollment of beneficiaries with renal or hepatic disease, or obesity in state Medicaid programs.

The efficacy of sevolflurane inhalation alone or its combination with intravenous remifentanil against withdrawal movements on rocuronium injection in children

Background

The aims of this study were to compare the efficacy of sevoflurane inhalation alone, intravenous remifentanil alone, and the combination of sevoflurane inhalation and remifentanil as pretreatment for the prevention of rocuronium-induced withdrawal movement in pediatric patients.

Methods

In this prospective, randomized study, 90 American Society of Anesthesiologists physical status I or II pediatric patients aged 3 to 10 years were randomly allocated to one of three treatment groups: The Group S comprising the patients receiving sevoflurane inhalation, the Group R comprising those doing intravenous remifentanil 0.5 µg/kg and the Group C comprising those doing sevoflurane inhalation+intravenous remifentanil 0.5 µg/kg. The response of the patients was graded based on a 4-point scale.

Results

The overall incidence of withdrawal movement on rocuronium injection was 54% (16/30) in the Group S, 57% (17/30) in the Group R and 17% (5/30) in the Group C. There was no significant difference in the incidence of withdrawal movements on rocuronium injection between the Group S and Group R. In addition, the incidence of withdrawal movements and generalized movement on rocuronium injection was significantly lower in the Group C as compared with the Group S and R (P < 0.05).

Conclusions

Our results indicate not only that there was no significant difference in the degree of the effect in lowering the incidence of withdrawal movements on rocuronium injection between sevoflurane inhalation and intravenous remifentanil but also that it was significantly higher when combined with intravenous remifentanil as compared with the single use of sevoflurane inhalation or intravenous remifentanil.

EC50 and EC95 of remifentanil to prevent rocuronium-induced withdrawal movements in children

Background

Intravenous administration of rocuronium induces intense pain in most patients (60-100%). This could be harmful during anesthesia induction because of the unintended reflex movement of an unconscious patient in response to the pain. Previous studies have reported that remifentanil effectively reduces rocuronium-induced pain and withdrawal movements. This study was designed to evaluate the EC₅₀ and EC₉₅ of remifentanil to prevent withdrawal movements in children.

Methods

We enrolled a total of 171 pediatric patients scheduled for general anesthesia in this study. Remifentanil was administrated by target-controlled infusion. Effect-site target concentrations ranged from 0.5 to 3.0 ng/ml. At each concentration, experiments were repeated in 10-20 patients. Propofol 2 mg/kg and rocuronium 0.9 mg/kg were administrated after equilibration of plasma and effect-site target remifentanil concentration. The withdrawal movements were graded on a 4-point scale. The EC₅₀ and EC₉₅ of remifentanil to prevent rocuronium-induced withdrawal movements were determined by using a logistic regression model.

Results

The logistic regression model showed that the probability of preventing rocuronium-induced withdrawal movement was as follows: exp (-3.49 + 2.07 × remifentanil concentration) / (1 + exp [-3.49 + 2.07 × remifentanil concentration]). EC₅₀ and EC₉₅ were 1.69 ng/ml (95% confidence intervals [CIs], 1.42-1.87) and 3.11 ng/ml (95% CIs, 2.79-3.72), respectively.

Conclusions

Administration of remifentanil at an effect-site target concentration of 3.1 ng/ml could effectively prevent rocuronium-induced withdrawal movements.

Direct effects of morphine but not of fentanyl-type opioids on human 5-HT3A receptors in outside-out patch-clamp studies

BACKGROUND

The alkaloid morphine is historically the oldest opiate, yet still today it has clinically important uses in analgesic therapies. The main analgesic effect of opioids, including synthetic opioids belonging to the family of 4-anilidopiperidines, is mediated via activation of opioid receptors spread throughout the peripheral and central nervous system. However, morphine acting as a 'dirty' drug also exhibits effects on other receptor systems, e.g., the serotonergic system and its 5-HT3 receptor. Therefore, this study focuses on the interaction of morphine and fentanyl-type opioids (alfentanil, remifentanil and sufentanil) with 5-HT3A receptors.

METHODS

Excised outside-out patches from human embryonic kidney-293 cells, stably transfected with the human 5-HT3A receptor cDNA, were used to determine the opioid effects using the patch-clamp technique.

RESULTS

Within clinical concentrations, the effects of morphine are concentration-dependent. Morphine reduced current amplitudes, as well as activation and decay time constants. These effects were not competitive. Contrary to these results, all fentanyl-type opioids only exerted effects far above their clinical concentration ranges. These effects were not homogenous but varying.

CONCLUSIONS

Morphine is an opioid compound exhibiting special antagonistic interaction with 5-HT3A receptors. This interaction is not shared by the newer synthetic derivatives of the fentanyl-type opioids in the clinical relevant concentration range.

Fentanyl-related compounds and derivatives: current status and future prospects for pharmaceutical applications

Fentanyl and its analogs have been mainstays for the treatment of severe to moderate pain for many years. In this review, we outline the structural and corresponding synthetic strategies that have been used to understand the structure-biological activity relationship in fentanyl-related compounds and derivatives and their biological activity profiles. We discuss how changes in the scaffold structure can change biological and pharmacological activities. Finally, recent efforts to design and synthesize novel multivalent ligands that act as mu and delta opioid receptors and NK-1 receptors are discussed.

Considerations for the use of short-acting opioids in general anesthesia

Anesthesiologists play a critical role in facilitating a positive perioperative experience and early recovery for patients. Depending on the kind of procedure or surgery, a wide variety of agents and techniques are currently available to anesthesiologists to administer safe and efficacious anesthesia. Notably, the fast-track or ambulatory surgery environment requires the use of agents that enable rapid induction, maintenance, and emergence combined with minimal adverse effects. Short-acting opioids demonstrate a safe and rapid onset/offset of effect; that short effect is both predictable and precise. It also ensures easier titration and reduced or rapidly reversed side effects. Due to their distinct pharmacokinetic and pharmacodynamic properties, and, in one case, rapid extra-hepatic clearance of remifentanil, these agents have several applications in general anesthesia.

Interaction between postoperative shivering and hyperalgesia caused by high-dose remifentanil

BACKGROUND

High-dose remifentanil-based anesthesia is associated with opioid-induced hyperalgesia (OIH) and postanesthetic shivering (PAS). These effects can be prevented by N-methyl-d-aspartate (NMDA) receptor antagonists. This study aimed to investigate correlations between OIH and PAS caused by high-dose remifentanil and the effects of low-dose ketamine on OIH and PAS.

METHODS

Seventy-five patients scheduled for single-port laparoscopic gynecologic surgery were randomly allocated into three groups, each of which received intraoperative remifentanil: group L at 0.1 µg/kg/min; group H at 0.3 µg/kg/min; and group HK at 0.3 µg/kg/min plus 0.25 mg/kg ketamine just before incision, followed by a continuous infusion of 5 µg/kg/min ketamine until skin closure.

RESULTS

PAS, postoperative tactile pain threshold, and the extent of hyperalgesia in group H were significantly different (P < 0.05) than in the other two groups. PAS was significantly correlated with OIH, including mechanically evoked pain such as postoperative tactile pain threshold (r = -0.529, P = 0.01) (r = -0.458, P = 0.021) and the extent of hyperalgesia (r = 0.537, P = 0.002) (r = 0.384, P = 0.031), respectively, in group H and group HK. Notably, both groups were treated with high-dose remifentanil. Tympanic membrane temperature, time to first postoperative analgesic requirement, postoperative pain scores, analgesic consumption, and cumulative patient-controlled analgesia volume containing morphine were comparable in all three groups.

CONCLUSIONS

OIH, including the enhanced perception of pain, and PAS were both associated with high-dose remifentanil, were significantly correlated and were attenuated by a low dose of ketamine. This suggests that a common mechanism in part mediated through activation of the central glutamatergic system (e.g., NMDA receptors), underlies the two effects caused by high doses of remifentanil.