Effect of A118G (rs1799971) single-nucleotide polymorphism of the μ-opioid receptor OPRM1 gene on intraoperative remifentanil requirements in Japanese women undergoing laparoscopic gynecological surgery

AIM

Abundant data are available on the effect of the A118G (rs1799971) single-nucleotide polymorphism (SNP) of the μ-opioid receptor OPRM1 gene on morphine and fentanyl requirements for pain control. However, data on the effect of this SNP on intraoperative remifentanil requirements remain limited. We investigated the effect of this SNP on intraoperative remifentanil requirements.

METHODS

We investigated 333 Japanese women, aged 21-69 years, who underwent laparoscopic gynecological surgery for benign gynecological disease under total intravenous anesthesia at Juntendo University Hospital. Average infusion rates of propofol and remifentanil during anesthesia and the average bispectral index (BIS) during surgery were recorded. Associations among genotypes of the A118G and phenotypes were examined with the Mann-Whitney U test.

RESULTS

The average propofol infusion rate was not different between patients with different genotypes. The average remifentanil infusion rate was significantly higher in patients with the AG or GG genotype than the AA genotype (p = 0.028). The average intraoperative BIS was significantly higher in patients with the GG genotype than the AA or AG genotype (p = 0.039).

CONCLUSIONS

The G allele of the A118G SNP was associated with higher intraoperative remifentanil requirements and higher intraoperative BIS values but was not associated with propofol requirements. Given that remifentanil and propofol act synergistically on the BIS, these results suggest that the G allele of the A118G SNP is associated with lower effects of remifentanil in achieving adequate intraoperative analgesia and in potentiating the sedative effect of propofol on the BIS.

Effect of Remimazolam Supplementation on Propofol Requirements During Hysteroscopy: A Double-Blind, Dose-Response Study

BACKGROUND

Propofol is commonly used for procedural sedation but may increase side effects in a dose-dependent manner. Remimazolam, an ultrashort-acting benzodiazepine, has been approved for procedural sedation but may delay awakening. This study tested the hypothesis that remimazolam as a supplement reduces effect-site propofol concentration (Ceprop) required to suppress response to cervical dilation in patients undergoing hysteroscopy.

METHODS

One hundred and fifty patients who were scheduled for hysteroscopy were randomized to receive 0, 0.05, 0.1, 0.15, or 0.2 mg·kg-1 intravenous remimazolam, followed by a bolus of sufentanil 0.15 μg⋅kg-1, and a target-controlled propofol infusion. The initial target Ceprop was 3.5 μg·mL-1 and was increased or decreased in subsequent patients by steps of 0.5 μg·mL-1 according to whether there was loss of response to cervical dilation in the previous patient. We used up-down sequential analysis to determine values of Ceprop that suppressed response to cervical dilation in 50% of patients (EC50).

RESULTS

The EC50 of propofol for suppressing response to cervical dilation was lower in patients given 0.1 mg·kg-1 (2.08 [95% confidence interval, CI, 1.88-2.28] μg·mL-1), 0.15 mg⋅kg-1 (1.83 [1.56-2.10] μg·mL-1), and 0.2 mg⋅kg-1 (1.43 [1.27-1.58] μg·mL-1) remimazolam than those given 0 mg⋅kg-1 (3.67 [3.49-3.86] μg·mL-1) or 0.05 mg⋅kg-1 (3.47 [3.28-3.67] μg·mL-1) remimazolam (all were P < .005). Remimazolam at doses of 0.1, 0.15, and 0.2 mg·kg-1 decreased EC50 of propofol by 43.3% (95% CI, 41.3%-45.5%), 50.3% (48.0%-52.8%), and 61.2% (58.7%-63.8%), respectively, from baseline (remimazolam 0 mg⋅kg-1). Propofol consumption was lower in patients given 0.1 mg⋅kg-1 (4.15 [3.51-5.44] mg·kg-1), 0.15 mg⋅kg-1 (3.54 [3.16-4.46] mg·kg-1), and 0.2 mg⋅kg-1 (2.74 [1.73-4.01] mg·kg-1) remimazolam than those given 0 mg⋅kg-1 (6.09 [4.99-7.35] mg·kg-1) remimazolam (all were P < .005). Time to anesthesia emergence did not differ significantly among the 5 groups.

CONCLUSIONS

For women undergoing hysteroscopic procedures, remimazolam at doses from 0.1 to 0.2 mg·kg-1 reduced the EC50 of propofol inhibiting response to cervical dilation and the total propofol requirement. Whether the combination could improve perioperative outcomes deserves further investigation.

Dexmedetomidine Pretreatment Confers Myocardial Protection and Reduces Mechanical Ventilation Duration for Patients Undergoing Cardiac Valve Replacement under Cardiopulmonary Bypass

PURPOSE

The study aims to assess the effects of dexmedetomidine (Dex) pretreatment on patients during cardiac valve replacement under cardiopulmonary bypass.

METHODS

For patients in the Dex group (n = 52), 0.5 μg/kg Dex was given before anesthesia induction, followed by 0.5 μg/kg/h pumping injection before aortic occlusion. For patients in the control group (n = 52), 0.125 ml/kg normal saline was given instead of Dex.

RESULTS

The patients in the Dex group had longer time to first dose of rescue propofol than the control group (P = 0.003). The Dex group required less total dosage of propofol than the control group (P = 0.0001). The levels of cardiac troponin I (cTnI), creatine kinase isoenzyme MB (CK-MB), malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) were lower in the Dex group than the control group at T4, 8 h after the operation (T5), and 24 h after the operation (T6) (P <0.01). The Dex group required less time for mechanical ventilation than the control group (P = 0.003).

CONCLUSION

The study suggests that 0.50 µg/kg Dex pretreatment could reduce propofol use and the duration of mechanical ventilation, and confer myocardial protection without increased adverse events during cardiac valve replacement.

Opioids in COVID-19: Two Sides of a Coin

Introduction: The treatment of most severe COVID-19 patients included the large-scale use of sedatives and analgesics-possibly in higher doses than usual-which was reported in the literature. The use of drugs that decrease mortality is necessary and opioids are important agents in procedures such as orotracheal intubation. However, these drugs seem to have been overestimated in the COVID-19 pandemic. We performed a review of the PubMed-Medline database to evaluate the use of opioids during this period. The following descriptors were used to enhance the search for papers: "Opioids", "COVID-19," "COVID-19 pandemic," "SARS-CoV-2," "Opioid use disorder," "Opioid dependence" and the names of the drugs used. We also evaluated the distribution of COVID-19 patients in Brazil and the applicability of opioids in our country during the COVID-19 pandemic. Results: Several positive points were found in the use of opioids in the COVID-19 pandemic, for instance, they can be used for analgesia in orotracheal intubation, for chronic pain management, and as coadjutant in the management of acute intensification of pain. However, high doses of opioids might exacerbate the respiratory depression found in COVID-19 patients, their chronic use can trigger opioid tolerance and the higher doses used during the pandemic might result in greater adverse effects. Unfortunately, the pandemic also affected individuals with opioid use disorder, not only those individuals are at higher risk of mortality, hospitalization and need for ventilatory support, but measures taken to decrease the SARS-CoV-2 spread such as social isolation, might negatively affect the treatment for opioid use disorder. In Brazil, only morphine, remifentanil and fentanyl are available in the basic health care system for the treatment of COVID-19 patients. Out of the 5,273,598 opioid units used in this period all over the country, morphine, fentanyl, and remifentanil, accounted for, respectively, 559,270 (10.6%), 4,624,328 (87.6%), and 90,000 (1.8%) units. Many Brazilian regions with high number of confirmed cases of COVID-19 had few units of opioids available, as the Southeast region, with a 0.23 units of opioids per confirmed COVID-19 case, and the South region, with 0.05 units. In the COVID-19 pandemic scenario, positive points related to opioids were mainly the occurrence of analgesia, to facilitate intubation and their use as coadjutants in the management of acute intensification of pain, whereas the negative points were indiscriminate use, the presence of human immunosuppressor response and increased adverse effects due to higher doses of the drug. Conclusion: The importance of rational and individualized use of analgesic hypnotics and sedative anesthetics should be considered at all times, especially in situations of high demand such as the COVID-19 pandemic.

Comparison of the effects of target-controlled infusion-remifentanil/midazolam and manual fentanyl/midazolam administration on patient parameters in dental procedures

Background

Moderate sedation is an integral part of dental care delivery. Target-controlled infusion (TCI) has the potential to improve patient safety and outcome. We compared the effects of using TCI to administer remifentanil/manual bolus midazolam with manual bolus fentanyl/midazolam administration on patient safety parameters, drug administration times, and patient recovery times.

Methods

In this retrospective chart review, records of patients who underwent moderate intravenous sedation over 12 months in a private dental clinic were assessed. Patient indicators (pre-, intra-, and post-procedure noninvasive systolic and diastolic blood pressure, respiration, and heart rate) were compared using independent t-test analysis. Patient recovery time, procedure length, and midazolam dosage required were also compared between the two groups.

Results

Eighty-five patient charts were included in the final analysis: 47 received TCI-remifentanil/midazolam sedation, and 38 received manual fentanyl/midazolam sedation. Among the physiological parameters, diastolic blood pressure showed slightly higher changes in the fentanyl group (P = 0.049), respiratory rate changes showed higher changes in the fentanyl group (P = 0.032), and the average EtCO₂ was slightly higher in the remifentanil group (P = 0.041). There was no significant difference in the minimum SpO₂ levels and average procedure length between the fentanyl and remifentanil TCI pump groups (P > 0.05). However, a significant difference was observed in the time required for discharge from the chair (P = 0.048), indicating that patients who received remifentanil required less time for discharge from the chair than those who received fentanyl. The dosage of midazolam used in the fentanyl group was 0.487 mg more than that in the remifentanil group; however, the difference was not significant (P > 0.05).

Conclusion

The combination of TCI administered remifentanil combined with manual administered midazolam has the potential to shorten the recovery time and reduce respiration rate changes when compared to manual administration of fentanyl/midazolam. This is possibly due to either the lower midazolam dosage required with TCI remifentanil administration or achieving a stable, steady-state low dose remifentanil concentration for the duration of the procedure.

Incidence of Adverse Effects of Propofol for Procedural Sedation/Anesthesia in the Pediatric Emergency Population: A Systematic Review and Meta-Analysis

BACKGROUND

To investigate the incidence of adverse effects of propofol among pediatric population for sedation or anesthesia.

METHODS

We performed Cochrane Library, PubMed, CNKI, VIP, and Wanfang databases to research relevant literature. We did sensitivity analysis to assess the incidence of adverse effects of propofol among pediatric population for sedation or anesthesia.

RESULTS

In 132 studies, eight RCTs were included in this analysis. The result showed that adverse events (bradypnea, hypotension, hypertension, and apnea) were significantly improved in the pediatric emergency population in the propofol group, but it had no effect on the incidence of cough attacks, desaturation, agitation, stridor, and laryngospasm. Furthermore, the subgroup analysis showed that those who received propofol for had decreased adverse effects compared with the patients who received ketamine treatment (SMD = 0.44, 95%CI = [0.28, 0.67], I 2 = 0%, and P = 0.0002), which demonstrated that propofol could decrease the incidence of adverse effects compared with ketamine and ketofol.

CONCLUSIONS

The study demonstrated that propofol may decrease the incidence of bradypnea, hypotension, hypertension, and apnea, but it had no effect on the incidence of cough attacks, desaturation, agitation, stridor, and laryngospasm. Furthermore, more large RCTs are needed to assess incidence of adverse effects of propofol among pediatric population.

Semimechanistic models to relate noxious stimulation, movement, and pupillary dilation responses in the presence of opioids

Intraoperative targeting of the analgesic effect still lacks an optimal solution. Opioids are currently the main drug used to achieve antinociception, and although underdosing can lead to an increased stress response, overdose can also lead to undesirable adverse effects. To better understand how to achieve the optimal analgesic effect of opioids, we studied the influence of remifentanil on the pupillary reflex dilation (PRD) and its relationship with the reflex movement response to a standardized noxious stimulus. The main objective was to generate population pharmacodynamic models relating remifentanil predicted concentrations to movement and to pupillary dilation during general anesthesia. A total of 78 patients undergoing gynecological surgery under general anesthesia were recruited for the study. PRD and movement response to a tetanic stimulus were measured multiple times before and after surgery. We used nonlinear mixed effects modeling to generate a population pharmacodynamic model to describe both the time profiles of PRD and movement responses to noxious stimulation. Our model demonstrated that movement and PRD are equally depressed by remifentanil. Using the developed model, we changed the intensity of stimulation and simulated remifentanil predicted concentrations maximizing the probability of absence of movement response. An estimated effect site concentration of 2 ng/ml of remifentanil was found to inhibit movement to a tetanic stimulation with a probability of 81%.

Induction and maintenance of procedural sedation in adults: focus on remimazolam injection

Introduction: Procedural sedation (PS) is a humane way to help patients get through painful medical procedures by the administration of sedative drugs combined with analgesics. However, each of the currently used medications has certain shortcomings, urging the search for a new drug. Remimazolam, a novel benzodiazepine, is an ultra-short-acting hypnotic agent invented out of the 'soft drug' development.Areas covered: This presented review provides an overview of the drugs used in clinical practice for the induction and maintenance of procedural sedation in adults, focusing on the newly investigated benzodiazepine remimazolam. Literature search was conducted using the MEDLINE and ClinicalTrial.gov databases from January 2007 to December 2020.Expert opinion: Based on the reported clinical trials so far, remimazolam has demonstrated its effectiveness and safety with promising properties including rapid onset, short duration of action, predictable and consistent recovery profile, metabolism almost unaffected by liver or renal function, with non or minimal cardiorespiratory depression, and availability with a reversal drug. With marketing approval received recently, remimazolam is expected to have a place in the practice for procedural sedation in the near future if its efficacy and safety are further confirmed by more clinical trials and post-market analyses.

Regulatory mechanisms and therapeutic potential of microglial inhibitors in neuropathic pain and morphine tolerance

Microglia are important cells involved in the regulation of neuropathic pain (NPP) and morphine tolerance. Information on their plasticity and polarity has been elucidated after determining their physiological structure, but there is still much to learn about the role of this type of cell in NPP and morphine tolerance. Microglia mediate multiple functions in health and disease by controlling damage in the central nervous system (CNS) and endogenous immune responses to disease. Microglial activation can result in altered opioid system activity, and NPP is characterized by resistance to morphine. Here we investigate the regulatory mechanisms of microglia and review the potential of microglial inhibitors for modulating NPP and morphine tolerance. Targeted inhibition of glial activation is a clinically promising approach to the treatment of NPP and the prevention of morphine tolerance. Finally, we suggest directions for future research on microglial inhibitors.

A comparison of ventilation with a non-invasive ventilator versus standard O2 with a nasal cannula for colonoscopy with moderate sedation using propofol

The aim of this study was to test the effects of CPAP on moderately sedated patients undergoing colonoscopy. Our hypothesis was that CPAP can reduce the incidence and duration of obstructive apnea and hemoglobin oxygen desaturation in patients undergoing procedural sedation for colonoscopy. Two groups of consenting adult patients scheduled to undergo routine colonoscopy procedures and sedated with propofol and fentanyl were monitored in this study: control and intervention. Patients in the intervention group were connected via a facemask to a ventilator that delivered supplemental oxygen (100%) through a standard air-cushion mask. The mask had a built-in leak to facilitate CO₂ clearance during CPAP. Patients in the control group received 2-10 L/min of oxygen via nasal cannula or non-rebreather mask. Subjects in the control group were collected in a prior study and used as historical controls. The primary outcome measures were the number of apneic events and the cumulative duration of apneic events. An apneic event was defined as a period longer than 10 s without respiration. The secondary outcome was the area under the curve (AUC) for the arterial oxygen saturation less than 90% versus time during sedative and analgesic administration (time (s) below threshold multiplied by percent below threshold). A desaturation event was defined as a period of time during which arterial oxygen saturation was less than 90%. 29 patients were enrolled in the intervention group and 156 patients were previously enrolled in the control group as part of an earlier study. The median number of apneic events in the control group was 7 compared to 0 in the intervention group. The intervention group experienced apnea less than 1% of the total procedure time compared to 17% in the control group (p < 0.001). There were no desaturation events observed in the 29 patients in the intervention group. In contrast, 27 out of 156 patients in the control group experienced a desaturation event. Average AUC of patients in the control group was 70%-s (time (s) * oxygen saturation below < 90%) (95% CI 32.34-108.60%) whereas the average AUC in intervention group patients was 0%-s (% time (s) * oxygen saturation < 90%) (95% CI 0-0%), p = 0.01. This preliminary study found that CPAP via a tight-fitting mask may be an effective tool to reduce the incidence and duration of obstructive apneic events as well as hemoglobin oxygen desaturation during lower endoscopy procedures that use propofol and fentanyl for sedation.Clinical Trial Registration ClinicalTrials.gov ID: NCT02623270. https://clinicaltrials.gov/ct2/show/NCT02623270 .

The use of remifentanil in critically ill patients undergoing percutaneous dilatational tracheostomy: A prospective randomized-controlled trial

Remifentanil was a μ-agonist, with a rapid onset, a powerful narcotic analgesic activity and a fast nonspecific esterases hydrolyzation and theoretically an ideal opioid for percutaneous dilatational tracheostomy (PDT). The present study discussed use of remifentanil in critically ill patients undergoing PDT. Ninety-nine patients were randomly assigned to the propofol/remifentanil group (PR group, n = 49) or the propofol group (P group, n = 50). Two patients (one in P group and one in PR group) were excluded and transferred to surgical way of tracheostomy because of uncontrolled bleeding. The primary outcomes were critical care pain observation (CPOT) scores during PDT; hemodynamic response and side effects, such as bleeding and muscle rigidity (MR). CPOT scores in P group were significantly higher than in PR group during incision and dilation stages (P < 0.05 and P < 0.01). Systolic blood pressure had a significant drop after a bolus of remifentanil in PR group compared with patients in P group (P < 0.056). The incidence of MR was significantly higher in PR group than in P group (P < 0.05). Recovery time in PR group was significantly shorter than in P group (P < 0.05). The occurrence of tachycardia, bleeding, vomiting, and nausea had no statistically differences in both groups. Patients in PR group were undergoing shorter recovery time and better experience of pain in PDT compared with patients in P group, but MR seemed to be higher in PR group. Remifentanil seemed to be a safe and effective opioid used in critically ill patients undergoing PDT.

Curative effect of remifentanil on labor analgesia in newborns

Objective: To investigate the curative effect of remifentanil on analgesia in newborns.Patients and methods: One hundred and twenty full-term puerperae from January 2013 to December 2013 were selected and randomly divided into three groups: remifentanil patient-controlled intravenous labor analgesia group (Group A, n = 40), patient-controlled epidural analgesia (PCEA) group (Group B, n = 40), and spontaneous labor group (Group C, n = 40). General conditions, visual analogue scale (VAS) score, labor stage, bleeding, delivery mode, neonatal asphyxia rate, oxyhemoglobin saturation in puerpera, and umbilical arterial blood gas analysis indexes of the fetus were measured. In addition, complications and adverse reactions were recorded.Results: VAS scores in Group A and B were significantly lower than that in Group C at each time point after analgesic intervention (p < .05), without differences at 30 min and 1 h after analgesia between Group A and B (p > .05). However, VAS scores in Group A were significantly higher than those in Group B at the full opening of the uterine orifice and fetal delivery (p < .05). The active phases in the first stage of labor in Group A and B were significantly shorter than that in Group C (p <.05). There were no significant differences in general conditions, VAS score before analgesia, the second and third stages of labor, delivery mode, bleeding, neonatal asphyxia rate, oxyhemoglobin saturation, pH value, partial pressure of oxygen (PO₂), and partial pressure of carbon dioxide (PCO₂) among three groups (p > .05).Conclusions: Remifentanil intravenous labor analgesia is not superior to PCEA, but does not increase adverse effects, suggesting it might be a supplementary method of PCEA.

Acute presentation of a partially obstructing laryngeal tumour: adjuvant agents to gaseous induction of anaesthesia

We present the case of a 53-year-old man who attended our emergency department with stridor. He had recently undergone investigation for possible glottic cancer. We discuss the airway management of such a case. We believe this to be the first description of propofol target controlled infusion and clonidine to supplement a sevoflurane gas induction, in order to obtund response to intubation while maintaining spontaneous ventilation. We also consider how airway interventions may impact prognosis and need to be considered.

Anesthesia in the Electrophysiology Laboratory

The electrophysiology suite is a foreign location to many anesthesiologists. The initial experience was with shorter procedures under conscious sedation, and the value of greater tailoring of the sedation/anesthesia by anesthesiologists was not perceived until practice patterns had already been established. Although better control of ventilation with general anesthesia may be expected, suppression of arrhythmias, blunting of the hemodynamic adaptation to induced arrhythmias, and interference by muscle relaxants with identification of the phrenic nerve may be seen. We review a range of electrophysiology procedures and discuss anesthetic approaches that balance patient safety and favorable outcomes.