Preliminary pharmacokinetics and pharmacodynamics of an ultra-short-acting opioid: remifentanil (GI87084B)

Efficacy, safety, and pharmacokinetics of MR13A11A, a generic of remifentanil, for pain management of Japanese patients in the intensive care unit: a double-blinded, fentanyl-controlled, randomized, non-inferiority phase 3 study

BACKGROUND

The aims of this study were to evaluate the efficacy, safety, and pharmacokinetics (PK) of continuous intravenous administration of remifentanil in mechanically ventilated patients in the intensive care unit (ICU).

METHODS

This was a multicenter, randomized, double-blinded, fentanyl-controlled, non-inferiority phase 3 study. Patients aged ≥ 20 years requiring 6 h to 10 days mechanical ventilation in an ICU and requiring pain relief were randomly assigned in a 1:1 ratio to receive either remifentanil (n = 98) or fentanyl (n = 98). Dose was titrated from an infusion rate of 1 mL/h (remifentanil: 0.025 µg/kg/min, fentanyl: 0.1 µg/kg/h) until the target level of analgesia (behavioral pain scale [BPS] ≤ 5 or numerical rating score [NRS] ≤ 3) was achieved by escalating the dose in 1 mL/h increasing. Administration was then adjusted to maintain the target level of analgesia until weaning from the ventilator. The primary endpoint was the proportion of patients who did not require rescue fentanyl. Safety was assessed according to standard procedures. PK of remifentanil in the arterial blood was assessed in 24 patients.

RESULTS

The proportion of patients achieving the primary endpoint in the remifentanil and fentanyl groups was 100% (92/92) and 97.8% (88/90), respectively. The difference between the groups was 2.2% (95% confidence interval, - 0.8-5.3) and non-inferiority of remifentanil to fentanyl was verified (p < 0.0001). The incidences of any adverse events in the remifentanil and fentanyl groups was 34 of 92 patients (37.0%) and 34 of 90 patients (37.8%), respectively. Adverse drug reactions was 12 in 92 patients (13.0%) and 15 in 90 patients (16.7%), respectively. In the PK analysis, blood remifentanil concentration decreased within 10 min to almost 50% of the end of administration, suggesting rapid offset of action following discontinuation of remifentanil.

CONCLUSIONS

Remifentanil can be used safely for pain management in mechanically ventilated Japanese patients in the ICU.

TRIAL REGISTRATION

Japan Registry of Clinical Trials, jRCT2080224954. Registered 20 November 2019, https://jrct.niph.go.jp/latest-detail/jRCT2080224954 .

The effect-site concentration of remifentanil blunting endotracheal intubation responses during anesthesia induction with etomidate: a dose-finding study

BACKGROUND

Remifentanil can inhibit the hemodynamic responses caused by endotracheal intubation, but the effect-site concentration of it required to control intubation responses when combined with etomidate has not been demonstrated. The purpose of this study was to determine the effect-site concentration of remifentanil blunting tracheal intubation responses in 50% and 95% of patients (EC₅₀ and EC₉₅) during etomidate anesthesia.

METHODS

American Society of Anesthesiologists physical status (ASA) I-II elective surgical patients receiving target-controlled infusion (TCI) of remifentanil, followed by etomidate and rocuronium for anesthesia were enrolled. The Belive Drive A2 monitor was used to calculate the MGRSSI (Maygreen Sedative state index) of hypnotic effect and the MGRNOX (Maygreen Nociception index) of nociception. The MGRSSI and the MGRNOX value were generated every 1 s. Mean arterial pressure (MAP) and heart rate (HR) were measured every minute, noninvasively. Using the modified Dixon's up-and-down method, the concentration of remifentanil was determined based on the intubation response of the previous patient. The cardiovascular response during endotracheal intubation was defined as positive when MAP or HR is 20% higher than the pre-intubation value. A probit analysis was used for calculating EC₅₀, EC₉₅ and 95% confidence interval (CI).

RESULTS

The EC₅₀ and EC₉₅ of remifentanil blunting tracheal intubation responses were found to be 7.731 ng/ml (95%CI: 7.212-8.278 ng/ml) and 8.701 ng/ml (95%CI: 8.199-11.834 ng/ml). There were statistically significant increases in HR, MGRSSI and MGRNOX value to tracheal intubation in the positive responses group compared to the negative group. The most common adverse event was postoperative nausea and vomiting, which occurred in 3 patients.

CONCLUSION

Remifentanil effect-site concentration of 7.731 ng/ml is effective in blunting sympathetic responses to tracheal intubation in 50% of patients when combined with etomidate anesthesia.

TRIAL REGISTRATION

The trial was registered at the Chinese Clinical Trials Registry ( www.chictr.org.cn , registration number: ChiCTR2100054565, date of registration: 20/12/2021).

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.

Comparison of clinical safety and efficacy of dexmedetomidine, remifentanil, and propofol in patients who cannot tolerate non-invasive mechanical ventilation: A prospective, randomized, cohort study

Background and objectives

Non-invasive ventilation (NIV) is used in intensive care units (ICUs) to treat of respiratory failure. Sedation and analgesia are effective and safe for improving compliance in patients intolerant to NIV. Our study aimed to evaluate the effects of dexmedetomidine, remifentanil, and propofol on the clinical outcomes in NIV intolerant patients.

Methods

This prospective randomized cohort study was conducted in a tertiary ICU, between December 2018 and December 2019. We divided a total of 120 patients into five groups (DEXL, DEXH, REML, REMH, PRO). IBM SPSS Statistics 20 (IBM Corporation, Armonk, New York, USA) was used to conduct the statistical analyses.

Results

The DEXL, DEXH, REML, and REMH groups consisted of 23 patients each while the PRO group consisted of 28 patients. Seventy-five patients (62.5%) became tolerant of NIV after starting the drugs. The NIV time, IMV time, ICU LOS, hospital LOS, intubation rate, side effects, and mortality were significantly different among the five groups (P = 0.05). In the groups that were given dexmedetomidine (DEXL, and DEXH), NIV failure, mortality, ICU LOS, and hospital LOS were lower than in the other groups.

Conclusion

In this prospective study, we compared the results of three drugs (propofol, dexmedetomidine, and remifentanil) in patients with NIV intolerance. The use of sedation increased NIV success in patients with NIV intolerance. NIV failure, mortality, ICU LOS, IMV time, and hospital LOS were found to be lower with dexmedetomidine.

Effects of Short-Acting Opioids on Intraocular Pressure during General Anesthesia: Systematic Review and Network Meta-Analysis

Intraocular pressure (IOP) is crucial to the well-being of eyes. During anesthesia, the administration of succinylcholine and endotracheal intubation are associated with an increase in IOP, which may be attenuated by short-acting opioids. However, the drug of choice among the commonly used short-acting opioids is unclear. This study aimed to evaluate the effects of fentanyl, sufentanil, alfentanil, and remifentanil on IOP measured after the administration of succinylcholine and after endotracheal intubation in patients undergoing general anesthesia. Five databases were searched. Randomized controlled trials (RCTs) that compared short-acting opioids and reported at least one of the clinical outcomes of interest were included. Nine RCTs with 357 patients were included. Remifentanil (1 μg kg⁻¹) more effectively alleviated the increase in IOP than the placebo after the administration of succinylcholine [mean difference (MD) of IOP, −3.64; confidence interval (CI), −5.47 to −1.81 and after endotracheal intubation (MD, −9.71; CI, −11.91 to −7.51). Remifentanil (1 μg kg⁻¹) ranked the best in terms of both attenuating the increase in IOP after the administration of succinylcholine [surface under the cumulative ranking curve (SUCRA), 0.91; normalized entropy (NE), 0.47; and after endotracheal intubation (SUCRA, 0.89; NE, 0.54) among all of the treatments. Remifentanil (1 μg kg⁻¹) should be considered the drug of choice in the circumstances where increased IOP is a great concern.

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.

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.

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%.

A Narrative Overview of Current Anesthetic Drugs in Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is a definitive treatment for patients with psychiatric disorders that are severe, acute, or refractory to pharmacologic therapy. Providing anesthesia for ECT is challenging, as the effect of drugs on hemodynamics, seizure duration, comfort, and recovery must be considered. We highlight and aim to review the common anesthetics used in ECT and related evidence. While drugs such as methohexital, succinylcholine, and etomidate have been used in the past, other drugs such as dexmedetomidine, ketamine, and remifentanil may provide a more balanced anesthetic with a greater safety profile in select populations. Overall, it is essential to consider the patient’s co-morbidities and associated risks when deciding on an anesthetic drug.

P2Y1 Purinergic Receptor Contributes to Remifentanil-Induced Cold Hyperalgesia via Transient Receptor Potential Melastatin 8-Dependent Regulation of N-methyl-d-aspartate Receptor Phosphorylation in Dorsal Root Ganglion

BACKGROUND

Remifentanil can induce postinfusion cold hyperalgesia. N-methyl-d-aspartate receptor (NMDAR) activation and upregulation of transient receptor potential melastatin 8 (TRPM8) membrane trafficking in dorsal root ganglion (DRG) are critical to cold hyperalgesia derived from neuropathic pain, and TRPM8 activation causes NMDAR-dependent cold response. Contribution of P2Y1 purinergic receptor (P2Y1R) activation in DRG to cold pain hypersensitivity and NMDAR activation induced by P2Y1R upregulation in neurons are also unraveled. This study explores whether P2Y1R contributes to remifentanil-induced cold hyperalgesia via TRPM8-dependent regulation of NMDAR phosphorylation in DRG.

METHODS

Rats with remifentanil-induced cold hyperalgesia were injected with TRPM8 antagonist or P2Y1R antagonist at 10 minutes before remifentanil infusion. Cold hyperalgesia (paw lift number and withdrawal duration on cold plate) was measured at -24, 2, 6, 24, and 48 hours following remifentanil infusion. After the last behavioral test, P2Y1R expression, TRPM8 expression and membrane trafficking, and NMDAR subunit (NR1 and NR2B) expression and phosphorylation in DRG were detected by western blot, and colocalization of P2Y1R with TRPM8 was determined by double-labeling immunofluorescence. Two-way repeated measures analysis of variance (ANOVA) or 2 × 2 factorial design ANOVA with repeated measures was used to analyze behavioral data of cold hyperalgesia. One-way ANOVA followed by Bonferroni post hoc comparisons was used to analyze the data in western blot and immunofluorescence.

RESULTS

Remifentanil infusion (1 μg·kg-1·min-1 for 60 minutes) induced cold hyperalgesia (hyperalgesia versus control, paw lift number and withdrawal duration on cold plate at 2-48 hours, P < .0001) with upregulated NR1 (hyperalgesia versus naive, 48 hours, mean ± standard deviation [SD], 114.00% ± 12.48% vs 41.75% ± 5.20%, P < .005) and NR2B subunits expression (104.13% ± 8.37% vs 24.63% ± 4.87%, P < .005), NR1 phosphorylation at Ser896 (91.88% ± 7.08% vs 52.00% ± 7.31%, P < .005) and NR2B phosphorylation at Tyr1472 (115.75% ± 8.68% vs 59.75% ± 7.78%, P < .005), TRPM8 expression (115.38% ± 9.27% vs 40.50% ± 4.07%, P < .005) and membrane trafficking (112.88% ± 5.62% vs 48.88% ± 6.49%, P < .005), and P2Y1R expression (128.25% ± 14.86% vs 45.13% ± 7.97%, P < .005) in DRG. Both TRPM8 and P2Y1R antagonists attenuated remifentanil-induced cold hyperalgesia and downregulated increased NR1 and NR2B expression and phosphorylation induced by remifentanil (remifentanil + RQ-00203078 versus remifentanil + saline, NR1 phosphorylation, 69.38% ± 3.66% vs 92.13% ± 4.85%; NR2B phosphorylation, 72.25% ± 6.43% vs 111.75% ± 11.00%, P < .0001). NMDAR activation abolished inhibition of TRPM8 and P2Y1R antagonists on remifentanil-induced cold hyperalgesia. P2Y1R antagonist inhibited remifentanil-evoked elevations in TRPM8 expression and membrane trafficking and P2Y1R-TRPM8 coexpression (remifentanil + 2'-deoxy-N6-methyl adenosine 3',5'-diphosphate [MRS2179] versus remifentanil + saline, coexpression, 8.33% ± 1.33% vs 22.19% ± 2.15%, P < .0001).

CONCLUSIONS

Attenuation of remifentanil-induced cold hyperalgesia by P2Y1R inhibition is attributed to downregulations in NMDAR expression and phosphorylation via diminishing TRPM8 expression and membrane trafficking in DRG.

Quantifying value-based determinants of drug and non-drug decision dynamics

RATIONALE

A growing body of research suggests that substance use disorder (SUD) may be characterized as disorders of decision making. However, drug choice studies assessing drug-associated decision making often lack more complex and dynamic conditions that better approximate contexts outside the laboratory and may lead to incomplete conclusions regarding the nature of drug-associated value.

OBJECTIVES

The current study assessed isomorphic (choice between identical food options) and allomorphic (choice between remifentanil [REMI] and food) choice across dynamically changing reward probabilities, magnitudes, and differentially reward-predictive stimuli in male rats to better understand determinants of drug value. Choice data were analyzed at aggregate and choice-by-choice levels using quantitative matching and reinforcement learning (RL) models, respectively.

RESULTS

Reductions in reward probability or magnitude independently reduced preferences for food and REMI commodities. Inclusion of reward-predictive cues significantly increased preference for food and REMI rewards. Model comparisons revealed that reward-predictive stimuli significantly altered the economic substitutability of food and REMI rewards at both levels of analysis. Furthermore, model comparisons supported the reformulation of reward value updating in RL models from independent terms to a shared, relative term, more akin to matching models.

CONCLUSIONS

The results indicate that value-based quantitative choice models can accurately capture choice determinants within complex decision-making contexts and corroborate drug choice as a multidimensional valuation process. Collectively, the present study indicates commonalities in decision-making for drug and non-drug rewards, validates the use of economic-based SUD therapies (e.g., contingency management), and implicates the neurobehavioral processes underlying drug-associated decision-making as a potential avenue for future SUD treatment.

Effect of continuous infusion of dexmedetomidine on blood loss in orthognathic surgery: a retrospective study

BACKGROUND

Patients with maxillofacial deformities require orthognathic surgeries to correct occlusion. The surgical procedure may lead to massive bleeding, which is associated with haematoma, respiratory obstruction, and asphyxia. Dexmedetomidine has been used in controlled hypotension and may reduce blood loss in orthognathic surgery. We conducted a retrospective cohort study to evaluate the effect of dexmedetomidine on blood loss in orthognathic surgeries.

METHODS

The primary outcome examined was blood loss, and secondary outcomes were postoperative haemoglobin level; intraoperative heart rate and blood pressure (T1: at incision; T2: 30 min after incision; T3: 60 min after incision; T4: 120 min after incision); dosage of fentanyl, remifentanil, urapidil, and esmolol; operation time; and incidence of allogeneic blood transfusion.

RESULTS

A total of 1247 patients were included in this study, and 540 patient pairs were matched via propensity score matching. There were significant decreases in mean blood loss, heart rate at T1-T4, blood pressure at T1, and remifentanil and esmolol dosage in the dexmedetomidine group compared with those in the control group. There was also a significant increase in the postoperative haemoglobin level of the dexmedetomidine group.

CONCLUSIONS

Continuous infusion of dexmedetomidine can decrease blood loss in orthognathic surgery.

TRIAL REGISTRATION

ChiCTR1800018794 (retrospectively registered) Name of registry: Chinese Clinical Trial Registry Date of registration: 2018/10/09 URL: www.chictr.org.cn/showproj.aspx?proj=30612.

Effect and Safety of Remifentanil Patient-Controlled Analgesia Compared with Epidural Analgesia in Labor: An Updated Meta-Analysis of Randomized Controlled Trials

PURPOSE

The study was aimed to systematically assess the effect and safety of remifentanil patient-controlled analgesia (rPCA) versus epidural analgesia (EA) during labor.

METHODS

Eligible trials were retrieved from PubMed, EMBASE, ScienceDirect, and Cochrane Library before April 2020. The primary outcomes were patient satisfaction with pain relief and average visual analog scale (VAS) pain scores during labor; the secondary outcomes were rate of spontaneous delivery, oxygen desaturation, maternal hyperthermia, and neonatal Apgar scores <7 at 1 and 5 min.

RESULTS

Eleven studies involving 3,039 parturients were included. We found that parturients receiving rPCA were similarly satisfied with pain relief compared to those receiving EA (standardized mean difference: -0.19; 95% confidence interval [CI]: -0.57, 0.18), though had significantly higher VAS pain scores during labor (weighted mean difference: 1.41; 95% CI: 0.32, 2.50). The rate of spontaneous delivery was comparable. rPCA increased the risk of maternal oxygen desaturation (risk ratio [RR]:3.23, 95% CI: 1.98, 5.30). There was no statistical significance regarding hyperthermia (RR: 0.49, 95% CI: 0.24, 1.01). No significant difference was found for neonatal Apgar scores <7 at 1 and 5 min.

CONCLUSION

rPCA could be an optional alternative for pain relief to EA without worsening maternal satisfaction with pain relief, delivery modes, or neonatal morbidity. However, rPCA was associated with higher pain intensity during labor and higher incidence of maternal oxygen desaturation. The routine use of rPCA in labor must be armed with close respiratory monitoring. Continued well-designed studies are required to provide more robust evidence.

Fentanyl versus Remifentanil for Cough Suppression and Recovery after Video-Assisted Thoracic Surgery

Background

Various methods have been used to reduce postoperative pain after thoracic surgery. However, these methods may affect the patient's respiratory response and delay recovery from anesthesia. We aimed to evaluate the effects of fentanyl and remifentanil during extubation after video-assisted thoracic surgery (VATS).

Methods

This study included 45 randomly-selected male patients who underwent VATS for pneumothorax between July 2011 and August 2012. We divided the participants into 3 groups: the F group, which received a bolus injection of 1.0 μg/kg of fentanyl; the R1 group, which received a 0.04 μg/kg/min remifentanil infusion; and the R2 group, which received a 0.08 μg/kg/min remifentanil infusion. Hemodynamics, pain, cough, consciousness level, and nausea were assessed for each group.

Results

The number and severity of coughs were lower in the R1 and R2 groups than in the F group, and there were no differences between the R1 and R2 groups. Respiratory depression and loss of consciousness were not observed in any of the patients, and there were no differences in hemodynamics.

Conclusion

In comparison with fentanyl, remifentanil did not result in a wide fluctuation of blood pressure and heart rate upon emergence from general anesthesia. Moreover, remifentanil contributed to cough suppression and postoperative pain control. Remifentanil seems to be a safe and effective analgesic after VATS.

Efficacy of different dose of dexmedetomidine combined with remifentanil in colonoscopy: a randomized controlled trial

Background

Dexmedetomidine has advantages during colonoscopy as it allows the patient to cooperate during the procedure. Few studies examined the dexmedetomidine-remifentanil combination. This study was to evaluate the effects of different doses of the dexmedetomidine-remifentanil combination in colonoscopy.

Methods

This was a prospective trial carried out at the Fourth Hospital of Hebei Medical University between 02/2018 and 10/2018. The patients were randomized: group I (dexmedetomidine 0.2 μg·kg^− 1), group II (dexmedetomidine 0.3 μg·kg^− 1), and group III (dexmedetomidine 0.4 μg·kg^− 1), all combined with remifentanil. The primary outcomes were the patient’s body movements during the procedure and adverse events.

Results

Compared with at admission (T₀), the SBP, HR, and RR at immediately after giving DEX (T₁), at the beginning of the examination (T₂), 5 min after the beginning of the examination (T₃), 10 min after the beginning of the examination (T₄), and at the end of the examination (T₅) in the three groups were all reduced (all P < 0.05), but all were within the clinically normal range. SpO₂ remained > 98% in all patients during the examination. Compared with T₀, the BIS values of the three groups were decreased at T₁ and T₂ (all P < 0.05). There were no significant differences in BIS among the three groups (all P > 0.05). The minimum BIS value in group III was lower than in groups I and II (P < 0.05). The degree of satisfaction with the anesthesia effect was higher in groups II and III that in group I (P < 0.05). No hypotension occurred, seven patients had bradycardia, and four patients had nausea/vomiting.

Conclusions

Dexmedetomidine 0.3 μg·kg^− 1 combined with remifentanil was effective for colonoscopy and had few adverse reactions.

Chinese Clinical Trial Registry: ChiCTR2000029105, Registered 13 January 2020 - Retrospectively registered.

Comparison of sedation between dexmedetomidine and propofol during transesophageal echocardiography: A randomized controlled trial

Background:

This study aimed to compare sedation characteristics of dexmedetomidine (Dex) and propofol during transesophageal echocardiography (TEE) in cardiac patients.

Methods:

This clinical trial was conducted on 65 cardiac patients, who underwent TEE in a referral heart hospital. The patients were randomly divided into two groups: Dex (n = 34) and propofol (n = 31). The depth of sedation in the patients was assessed at 5-min intervals until the end of the TEE examination. The patient, physicians’ satisfaction was recorded. Furthermore, blood pressure, heart and respiratory rates, peripheral oxygen saturation, and the bispectral index (BIS) of the patients were measured. The occurrence of apnea, hypotension or bradycardia was documented.

Results:

Demographic variables were similar in both groups. Time from the beginning of sedation to the start of TEE was significantly longer in the Dex group (P = 0.01). Duration of the TEE examination was not different between the two groups. Interestingly, the recovery time was shorter in the Dex group than in the propofol group. There were no significant differences regarding patient and physician satisfaction with sedation quality. Hemodynamic profile was mainly similar in both groups. There was a significantly lower BIS level in the Dex group. There was no significant difference in the incidence of apnea or hypotension between the groups.

Conclusions:

Time from the beginning of sedation with Dex was longer than that with propofol. However, Dex was able to provide satisfactory sedation levels, hemodynamic stability, short recovery time, and acceptable patient and practitioner satisfaction during TEE in our cardiac patients.

Effectiveness Comparison of Dexmedetomidine and Remifentanil for Perioperative Management in Patients Undergoing Endoscopic Sinus Surgery

BACKGROUND

For patients undergoing endoscopic sinus surgery, intranasal injection of epinephrine can cause acute increases in heart rate and blood pressure.

OBJECTIVE

Among the drugs for reducing hyperdynamic effects, dexmedetomidine and remifentanil are expected to blunt the acute hemodynamic responses after intranasal injection of epinephrine. Our study compared a difference in the 2 drugs in their abilities to blunt the hemodynamic responses in intraoperative period and postoperative profile.

METHODS

In this study, the patients were randomly divided into the dexmedetomidine and remifentanil groups. During the intraoperative period, the hemodynamic values were recorded. The surgical condition was assessed by a single surgeon. During the postoperative period, hemodynamic values, sedation scale score, and pain score were recorded.

RESULT

No significant differences in hemodynamic variables were found between the groups before and after intranasal injection of epinephrine. Comparison of the group mean values before endotracheal intubation revealed that the blood pressure values in the remifentanil group were significantly lower than those in the dexmedetomidine group. At 2 minutes after endotracheal intubation, blood pressure and heart rate values in the remifentanil group were significantly lower than those in the dexmedetomidine group. The sedation score was significantly lower in the dexmedetomidine group on arrival and at 30 minutes after arrival at the postanesthetic care unit (P < .001 and P = .001, respectively). At 30 and 60 minutes after the operation, the pain scores were significantly lower in the dexmedetomidine group (P = .015 and P = .001, respectively).

CONCLUSION

Dexmedetomidine had better postoperative sedative and analgesic effects than remifentanil for patients undergoing endoscopic sinus surgery in this study. Remifentanil and dexmedetomidine attenuated acute hemodynamic responses to be within normal ranges after intranasal injection of epinephrine, and no significant differences in terms of hemodynamic variables. Remifentanil was superior to dexmedetomidine in inducing hypotension during endotracheal intubation.

Dextromethorphan and bupropion reduces high level remifentanil self-administration in rats

Opiate addiction has risen substantially during the past decade. New treatments to combat opiate addiction are sorely needed. The current study was conducted to determine the acute individual and interactive effects of bupropion and dextromethorphan in a rat model of opiate self-administration using the short-acting synthetic opioid remifentanil. Both of these drugs have been found to reduce self-administration of nicotine. Bupropion and dextromethorphan and their combination had differential effects depending on whether the rats showed higher or lower baseline remifentanil self-administration. The rats with higher initial remifentanil self-administration showed a significant decrease in remifentanil self-administration with bupropion or dextromethorphan treatment, compared to the vehicle control condition. This decrease in self-remifentanil administration was most pronounced when combination of the higher doses of bupropion and dextromethorphan were administered. In contrast, the rats with lower baseline remifentanil self-administration showed the opposite effect of drug treatment with an increase in remifentanil self-administration with bupropion treatment compared to the vehicle control condition. Dextromethorphan had no significant effect inthis group. This study shows that combination bupropion and dextromethorphan affects remifentanil self-administration in a complex fashion with differential effects on low and high baseline responders. In subjects with high baseline remifentanil self-administration, bupropion and dextromethorphan treatment significantly reduced self-administration, whereas in subjects with low baseline remifentanil self-administration, bupropion increased remifentanil self-administration and dextromethorphan had no discernible effect. This finding suggests that combination bupropion-dextromethorphan should be tested in humans, with a focus on treating people with high-level opiate use.

Implementation of a Reduced Opioid Utilization Protocol for Radical Cystectomy

BACKGROUND: Radical cystectomy (RC) often requires a prolonged course of opioid medications for postoperative pain management. We implemented a Reduced Opioid Utilization (ROU) protocol to decrease exposure to opioid medications. OBJECTIVE: To determine the impact of the ROU protocol on opioid exposure, pain control, inpatient recovery, and complication rates among patients who underwent RC. METHODS: The ROU protocol includes standardized recovery pathways, a multimodal opioid-sparing pain regimen, and improved patient and provider education regarding non-opioid medications. Opioid exposure was calculated as morphine equivalent dose (MED), and was compared between RC patients following the ROU protocol and patients who previously followed our traditional pathway. Opioid-related adverse drug events (ORADEs), pain scores, length of stay, and 90-day complications, readmission, and mortality were also compared between cohorts. RESULTS: 104 patients underwent RC, 54 (52%) of whom followed the ROU protocol. ROU patients experienced a statistically significant decrease in opioid exposure in the post-anesthesia care unit (p = 0.003) and during their postoperative recovery (85.7±21.0 MED vs 352.6±34.4 MED, p < 0.001). The ROU protocol was associated with a statistically significant decrease in ORADEs after surgery. There was no significant difference in average pain scores, length of stay, readmissions, or 90-day complication or mortality rates. CONCLUSIONS: The ROU protocol decreased opioid use by 77% without compromising pain control or increasing the rate of complications. This study demonstrates the efficacy of non-opioid medications in controlling postoperative pain, and highlights the role providers can play to decrease patient exposure to opioids after RC surgery.

Total intravenous anaesthesia in ambulatory care

PURPOSE OF REVIEW

The purpose of this article is to review the use of total intravenous anaesthesia (TIVA) in ambulatory care.

RECENT FINDINGS

The number of ambulatory surgery cases is likely to increase in coming years. Recent meta-analyses suggest that TIVA offers decreased postoperative nausea and vomiting (PONV) and decreased pain scores in the postanaesthesia care unit (PACU) in day case/ambulatory surgery patients when compared with volatile anaesthesia. Particular improvements have also been shown in endoscopic nasal surgery in terms of decreased blood loss. TIVA consistently scores higher than volatile techniques in patient satisfaction surveys. Surveys of anesthetists suggest that TIVA is not in widespread use. This may be because of the perceived lack of training or confidence in the technique, therefore, recent internationally agreed guidelines aimed at formalizing its practice are welcome. There is also some recent evidence to suggest that intraoperative dexmedetomidine is superior to remifentanil with respect to postoperative pain and speed of recovery, and that intraoperative lignocaine infusion may reduce chronic pain incidence in breast surgery.

SUMMARY

Review of recent evidence of TIVA's use in ambulatory surgery and summary of new international guidelines on its use.

Effect of remifentanil infusion on the hemodynamic response during induction of anesthesia in hypertensive and normotensive patients: a prospective observational study

Background

The induction of general anesthesia may cause hemodynamic instability. Remifentanil is often administered to suppress the hemodynamic response. We aimed to evaluate the effect of remifentanil infusion on the hemodynamic response to induction of anesthesia in hypertensive and normotensive patients.

Methods

Patients were divided into two groups: Group H (n = 102) were hypertensive patients and Group C (n = 107) were normotensive patients. During induction, all patients received 1 µg/kg of remifentanil as a loading dose over 2 minutes, followed by a continuous infusion at 0.05 µg/kg/minute. We analyzed the systolic, diastolic, and mean pressures and heart rate pre-induction, pre-intubation, immediately post-intubation, and at 2, 4, 6, 8, and 10 minutes after intubation.

Results

The systolic, diastolic, and mean pressures before induction were significantly higher in group H compared with group C, but there was no significant difference between the two groups immediately after intubation. Blood pressures immediately after intubation were similar to the pre-induction blood pressure. There was no significant difference in heart rate between the two groups at any time point.

Conclusions

Remifentanil infusion effectively attenuates the hemodynamic response to induction of general anesthesia in hypertensive and normotensive patients.

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.

Comparison of the efficacy and safety of remifentanil versus different pharmacological approaches on prevention of etomidate-induced myoclonus: a meta-analysis of randomized controlled trials

Objective: Myoclonus was considered as one conundrum in etomidate induction, which led to multiple risks during clinical anesthesia. The present study was conducted to compare the efficacy of pretreatment with remifentanil to different pharmacological approaches on reducing etomidate-induced myoclonus.

Methods: We searched PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure from the inception to October 2018. Randomized controlled trials comparing remifentanil versus other pharmacological approaches in reducing etomidate-induced myoclonus were eligible to be analyzed.

Results: Overall, 13 trials with 1,392 patients met with the inclusion criteria. 1) Pretreatment with remifentanil could reduce the incidence of etomidate-induced myoclonus compared to placebo and fentanyl; few differences were found between the use of remifentanil and the use of midazolam: (incidence of myoclonus: 5.56% with remifentanil vs 71.65% with saline, RR=0.08, with 95% CI [0.05, 0.12], P<0.0001; 3.80% with remifentanil vs 13.33% with fentanyl, RR with 95% 0.31 [0.11, 0.86], P=0.02; 46.00% with remifentanil vs 55.45% with midazolam, RR=0.82, with 95% CI [0.64, 1.06], P=0.13). 2) Compared with placebo, pretreatment with remifentanil could reduce the incidence of mild, moderate, and severe myoclonus; compared with midazolam, patients receiving remifentanil experienced lower occurrence of severe myoclonus; compared with fentanyl, pretreatment with remifentanil associated with significant low occurrence of moderate and severe myoclonus. 3) The outcomes also indicated that pretreatment with remifentanil could prevent excessive hemodynamic changes after endotracheal intubation compared to fentanyl.

Conclusions: Pretreatment with remifentanil could be considered as one operative option to reduce both incidence and severity of etomidate-induced myoclonus. Compared with fentanyl, it also provides efficacy in preventing excessive hemodynamic changes after endotracheal intubation. However, the best treatment and the proper prophylactic dosage calls for more high quality evidence with large sample size.

Evidence-based clinical guidelines on analgesia and sedation in newborn infants undergoing assisted ventilation and endotracheal intubation

AIM

This review informed pain control guidelines for clinicians performing mechanical ventilation, nasal continuous positive airway pressure and endotracheal intubation on term and preterm newborn infants.

METHODS

We reviewed literature published between 1986 and June 2017 on analgesia and sedation during assisted ventilation and before endotracheal intubation in newborn infants admitted to neonatal intensive care units. The subsequent guidelines were developed using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Our review produced five strong standard of care recommendations. One, reduce neonatal stress and use nonpharmacological analgesia during invasive ventilation. Two, favour intermittent boluses of opioids, administered after pain scores and before invasive procedures, during short expected periods of mechanical ventilation, mainly in preterm infants affected by respiratory distress syndrome. Three, do not use morphine infusion in preterm infants under 27 gestational weeks. Four, always use algometric scores to titrate analgesic drugs doses. Five, use premedication before endotracheal intubation for a more rapid, less painful, less traumatic and safer manoeuvre. We also developed 30 conditional recommendations on therapeutic options.

CONCLUSION

Our review produced 35 recommendations on standard care and therapeutic options relating to the analgesia and sedation of newborn infants during ventilation and before endotracheal intubation.

Optimal effective-site concentration of remifentanil for sedation during plate removal of maxilla

Background

Removal of the plate following Le Fort I osteotomy and BSSO (bilateral sagittal split osteotomy) is a common procedure. However, patients who undergo plate removal experience intense pain and discomfort. This study investigated the half-maximal effective concentration (Ce₅₀) of remifentanil in the prevention of plate removal pain under sedation using dexmedetomidine.

Methods

The study evaluated 18 patients, between 18 and 35 years of age, scheduled for elective surgery. Remifentanil infusion was initiated after sedation using dexmedetomidine, and started at a dose of 1.5 ng/mL on the first patient via target-controlled infusion (TCI). Patients received a loading dose of 1.0 µg/kg dexmedetomidine over 10 min, followed by a maintenance dose of 0.7 µg/kg/h. When the surgeon removed the plate, the patient Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score was observed.

Results

The Ce of remifentanil ranged from 0.9 to 2.1 ng/mL for the patients evaluated. The estimated effect-site concentrations of remifentanil associated with a 50% and 95% probability of reaching MOAA/S score of 3 were 1.28 and 2.51 ng/mL, respectively.

Conclusions

Plate removal of maxilla can be successfully performed without any pain or adverse effects by using the optimal remifentanil effect-site concentration (Ce₅₀, 1.28 ng/mL; Ce₉₅, 2.51 ng/mL) combined with sedation using dexmedetomidine.

Optimal neuromuscular blocking effects of remifentanil during tracheal intubation under general anesthesia

Objective

This study was performed to determine the effect of the remifentanil dose on the onset time of rocuronium with electromyography.

Methods

This retrospective comparative study included 75 patients undergoing general anesthesia for elective surgery. Patients received lidocaine (40 mg) and propofol (2 mg/kg) followed by rocuronium (0.6 mg/kg) with either saline infusion (Group S), remifentanil at 0.5 µg/kg/minute (Group R 0.5), or remifentanil at 1.0 µg/kg/minute (Group R 1.0). Neuromuscular block was monitored by train-of-four (TOF) electromyography, and the times taken to reach TOF 0 and TOF ratio (TOFR) 25% were recorded.

Results

The times taken to reach TOF 0 and TOFR 25% were significantly higher in Groups R 0.5 and R 1.0 than in Group S. The time taken to reach TOF 0 was 130.0 ± 6.4 s in Group S, 142.6 ± 6.0 s in Group R 0.5, and 183.0 ± 11.6 s in Group R 1.0. The time taken to reach TOFR 25% was also higher in Groups R 0.5 and R 1.0 than in Group S.

Conclusions

As the remifentanil dose increases, the intubation time required to reach TOF 0 also increases. Remifentanil has an effect on the onset of rocuronium.

Anesthetic Management of Narcolepsy Patients During Surgery: A Systematic Review

BACKGROUND

Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness, sleep paralysis, and/or hypnagogic/hypnopompic hallucinations, and in some cases cataplexy. The response to anesthetic medications and possible interactions in narcolepsy patients is unclear in the perioperative period. In this systematic review, we aim to evaluate the current evidence on the perioperative outcomes and anesthetic considerations in narcolepsy patients.

METHODS

Electronic literature search of Medline, Medline in-process, Embase, Cochrane Database of Systematic Reviews databases, international conference proceedings, and abstracts was conducted in November 2015 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols guideline. A total of 3757 articles were screened using a 2-stage strategy (title-abstract followed by full text). We included case studies/series, cohort studies, and randomized controlled trials of narcolepsy patients undergoing surgical procedures under anesthesia or sedation. Preoperative narcolepsy symptoms and sleep study data, anesthetic technique, and perioperative complications were extracted. Screening of articles, data extraction, and compilation were conducted by 2 independent reviewers and any conflict was resolved by the senior author.

RESULTS

A total of 19 studies including 16 case reports and 3 case series were included and evaluated. The majority of these patients received general anesthesia, whereas a small percentage of patients received regional anesthesia. Reported complications of narcolepsy patients undergoing surgeries were mainly related to autonomic dysregulation, or worsening of narcolepsy symptoms intra/postoperatively. Narcolepsy symptoms worsened only in those patient populations where the preoperative medications were either discontinued or reduced (mainly in obstetric patients). In narcolepsy patients, use of depth of anesthesia monitoring and total intravenous technique may have some advantage in terms of safety profile. Several patients undergoing neurosurgery involving the hypothalamus or third or four ventricles developed new-onset narcolepsy.

CONCLUSIONS

We found a paucity of prospective clinical trials in this patient population, as most of the studies were case reports or observational studies. Continuation of preoperative medications, depth of anesthesia monitoring, use of multimodal analgesia with short-acting agents and regional anesthesia techniques were associated with favorable outcomes. Obstetric patients may be at greater risk for worsening narcolepsy symptoms, possibly related to a reduction or discontinuation of medications. For neurosurgical procedures involving the hypothalamus or third and fourth ventricle, postoperative considerations should include monitoring for symptoms of narcolepsy. Future studies are needed to better define perioperative risks associated with anesthesia and surgery in this population of patients.

Efficacy and safety of remifentanil for analgesia in cesarean delivery

BACKGROUND

This study aimed to assess the efficacy and safety of remifentanil as a general anesthetic during cesarean delivery.

MATERIAL AND METHODS

Fifty women with singleton pregnancies undergoing cesarean delivery were randomly divided into intervention and control groups, each group containing 25 subjects. Participants in the intervention group received remifentanil (infused at 2 μg/kg/h), whereas subjects in the control group were given dexmedetomidine (infused at 0.4 μg/kg/h). Outcome measurements included mean arterial blood pressure (MAP), heart rate (HR), bispectral index (BIS), Apgar scores at 1 and 5 minutes, and the pH, PCO2, PO2, and base excess (BE) of umbilical venous and arterial blood.

RESULTS

Forty-four participants completed the study. Patients in the intervention group did not experience greater effect and safety than those in the control group (P > .05), although MAP and BIS values decreased significantly immediately before laryngoscopy (P < .05). In addition, BIS values were reduced significantly at the time of skin incision, at uterine incision, and immediately after fetal delivery when compared with baseline values in both groups (P < .01).

CONCLUSION

This study concluded that remifentanil and dexmedetomidine exhibited similar efficacy and safety during general anesthesia for cesarean delivery.

Population pharmacokinetics of remifentanil in critically ill patients receiving extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is associated with pharmacokinetic (PK) changes of drugs. It presents considerable challenges to providing optimal dosing regimens for patients receiving ECMO. We aimed to describe the population PK of remifentanil in critically ill adult patients receiving venoartrial extracorporeal membrane oxygenation (VA-ECMO) and to identify determinants associated with altered remifentanil concentrations. The population PK model of remifentanil was developed using nonlinear mixed effects modelling (NONMEM). Fifteen adult patients who received a continuous infusion of remifentanil during VA-ECMO participated in the study. The PK of remifentanil was best described by a one-compartment model with additive and proportional residual errors. Remifentanil concentrations were affected by sex and ECMO pump speed. The final PK model included the effect of sex and ECMO pump speed on clearance is developed as followed: clearance (L/h) = 366 × 0.502sex × (ECMO pump speed/2350)2.04 and volume (L) = 41. Remifentanil volume and clearance were increased in adult patients on VA-ECMO compared with previously reported patients not on ECMO. We suggest that clinicians should consider an increased remifentanil dosing to achieve the desired level of sedation and provide a dosing regimen according to sex and ECMO pump speed.

Effect-site concentration of remifentanil required to blunt haemodynamic responses during tracheal intubation: A randomized comparison between single- and double-lumen tubes

Objective

To investigate the effect-site concentration of remifentanil required to blunt haemodynamic responses during tracheal intubation with a single-lumen tube (SLT) or a double-lumen tube (DLT).

Methods

Patients scheduled for thoracic surgery requiring one-lung ventilation were randomly allocated to either the SLT or DLT group. All patients received a target-controlled infusion of propofol and a predetermined concentration of remifentanil. Haemodynamic parameters during intubation were recorded. The effect-site concentration of remifentanil was determined using a delayed up-and-down sequential allocation method.

Results

A total of 92 patients were enrolled in the study. The effective effect-site concentrations of remifentanil required to blunt haemodynamic responses in 50% of patients (EC₅₀) estimated by isotonic regression with bootstrapping was higher in the DLT than the SLT group (8.5 ng/ml [95% confidence interval (CI) 8.0–9.5 ng/ml] versus 6.5 ng/ml [95% CI 5.6–6.7 ng/ml], respectively). Similarly, the effective effect-site concentrations of remifentanil in 95% of patients in the DLT group was higher than the SLT group (9.9 ng/ml [95% CI 9.8–10.0 ng/ml] versus 7.0 ng/ml [95% CI 6.9–7.0 ng/ml], respectively).

Conclusions

This study demonstrated that a DLT requires a 30% higher EC₅₀ of remifentanil than does an SLT to blunt haemodynamic responses during tracheal intubation when combined with a target-controlled infusion of propofol.

Trial registration

Clinicaltrials.gov identifier: NCT01542099.

Application of calibrated forceps for assessing mechanical nociception with high time resolution in mice

In order to investigate the basic physiological mechanisms of pain and the anti-nociceptive effects of analgesics, development of pain assays in mice is critical due to the advances of genetic manipulation techniques. The von Frey hairs/Semmes-Weinstein monofilaments test (von Frey test) has long been applied to examine mechanical nociception in mice. Though the von Frey test is a well-established and standardized method, it is inappropriate to assess a rapid change in the nociceptive threshold because voluntary resting/sleeping states are necessary to examine the response. In this study, we assessed the effectiveness of calibrated forceps to determine the mechanical nociceptive threshold in mice. Repeated daily measurements of the threshold over 5 days indicated that the device obtained stable and reliable values. Furthermore, repeated measurements with 5 minute intervals revealed that the device detected the rapid change of the threshold induced by remifentanil, a short-acting μ-receptor agonist. These results indicate that the calibrated forceps are well-suited for measuring the mechanical nociceptive threshold in mice, and are useful in assessing the effects of short-acting analgesics on mechanical nociception.

Safety of remifentanil in transsphenoidal surgery: A single-center analysis of 540 patients

Although some studies have examined the efficacy and safety of remifentanil in patients undergoing neurosurgical procedures, none has examined its safety in transsphenoidal operations specifically. In this study, all transsphenoidal operations performed by a single author from 2008 to 2015 were retrospectively reviewed to evaluate the safety of remifentanil in a consecutive series of patients. During the study period, 540 transsphenoidal operations were identified. Of these, 443 (82.0%) patients received remifentanil intra-operatively; 97 (18.0%) did not. The two groups were well-matched with regard to demographic categories, comorbidities, and pre-operative medications (p>0.05), except pre-operative tobacco use (p=0.021). Patients were also well-matched with regard to radiographic features and surgical techniques. Patients who received remifentanil were more likely to harbor a macroadenoma (78.1% vs. 67.0%, p=0.025), and had slightly longer anesthesia time on average (269.2minvs. 239.4min, p=0.024). All pathologic diagnoses were well-matched between the two groups, except that patients receiving remifentanil were more likely to harbor a non-functioning adenoma (46.5% vs. 26.8%, p<0.001). Analysis of post-operative complications showed no significant difference between patients who received remifentanil and those who did not, and length of stay and prevalence of ICU stay did not differ between the two groups. In a well-matched series of 540 patients undergoing transsphenoidal surgery, remifentanil was found to be a safe anesthetic adjunct. There were no significant differences in post-operative hospital course or complications in patients who did and did not receive intra-operative remifentanil.

Remifentanil in electroconvulsive therapy: a systematic review and meta-analysis of randomized controlled trials

In electroconvulsive therapy (ECT), remifentanil is often used concurrently with anesthetics. The objective of this study was to provide an up-to-date and comprehensive review on how the addition of remifentanil to anesthetics affects seizure duration and circulatory dynamics in mECT. We performed a meta-analysis of RCTs that investigated seizure duration and circulatory dynamics in patients treated with ECT using anesthetics alone (non-remifentanil group) and with anesthetics plus remifentanil (remifentanil group). A total of 13 RCTs (380 patients and 1024 ECT sessions) were included. The remifentanil group showed a significantly prolonged seizure duration during ECT compared to the non-remifentanil group [motor: 9 studies, SMD = 1.25, 95 % CI (0.21, 2.29), p = 0.02; electroencephalogram: 8 studies, SMD = 0.98, 95 % CI (0.14, 1.82), p = 0.02]. The maximum systolic blood pressure (SBP) was significantly reduced in the remifentanil group compared to the non-remifentanil group [7 studies, SMD = -0.36, 95 % CI (-0.65, 0.07), p = 0.02]. Substantial heterogeneity was observed for meta-analyses for seizure durations, but a pre-planned subgroup analysis revealed that seizure duration was prolonged only when the use of the anesthetic dose was reduced in the remifentanil group. The results of our study suggest that addition of remifentanil to anesthesia in ECT may lead to prolonged seizure duration when it allows the use of reduced anesthetic doses. Further, the addition of remifentanil was associated with reduced maximum SBP.

Pharmacogenomics and pharmacogenetics for the intensive care unit: a narrative review

PURPOSE

Knowledge of how alterations in pharmacogenomics and pharmacogenetics may affect drug therapy in the intensive care unit (ICU) has received little study. We review the clinically relevant application of pharmacogenetics and pharmacogenomics to drugs and conditions encountered in the ICU.

SOURCE

We selected relevant literature to illustrate the important concepts contained within.

PRINCIPAL FINDINGS

Two main approaches have been used to identify genetic abnormalities - the candidate gene approach and the genome-wide approach. Genetic variability in response to drugs may occur as a result of alterations of drug-metabolizing (cytochrome P [CYP]) enzymes, receptors, and transport proteins leading to enhancement or delay in the therapeutic response. Of relevance to the ICU, genetic variation in CYP-450 isoenzymes results in altered effects of midazolam, fentanyl, morphine, codeine, phenytoin, clopidogrel, warfarin, carvedilol, metoprolol, HMG-CoA reductase inhibitors, calcineurin inhibitors, non-steroidal anti-inflammatory agents, proton pump inhibitors, and ondansetron. Changes in cholinesterase enzyme function may affect the disposition of succinylcholine, benzylisoquinoline muscle relaxants, remifentanil, and hydralazine. Genetic variation in transport proteins leads to differences in the response to opioids and clopidogrel. Polymorphisms in drug receptors result in altered effects of β-blockers, catecholamines, antipsychotic agents, and opioids. Genetic variation also contributes to the diversity and incidence of diseases and conditions such as sepsis, malignant hyperthermia, drug-induced hypersensitivity reactions, cardiac channelopathies, thromboembolic disease, and congestive heart failure.

CONCLUSION

Application of pharmacogenetics and pharmacogenomics has seen improvements in drug therapy. Ongoing study and incorporation of these concepts into clinical decision making in the ICU has the potential to affect patient outcomes.

Accidental administration of the remifentanil formulation Ultiva™ into the epidural space and the complete time course of its consequences: a case report

Background

Ultiva™ contains the potent short-acting μ-opioid receptor agonist remifentanil hydrochloride, and it is commonly administered intravenously during general anesthesia. It is not approved for epidural or intrathecal use in clinical practice because it contains glycine as an acidic buffer. However, at this moment, very limited information is available on epidural administration of Ultiva™.

Case presentation

We report the accidental administration of 300 μg of remifentanil and 2.25 mg of glycine into the epidural space after emergence from general anesthesia for distal pancreatectomy and the complete time course of its consequences. The respiratory depression occurred at 5 min after the administration, and complete loss of consciousness was observed at 8 min. The patient was re-intubated and underwent mechanical respiration. At 45 min (33 min after re-intubation), spontaneous respiration resumed, she was responsive to commands, and her orientation returned. She was extubated successfully.

Conclusions

These consequences might have resulted from the diffusion of the components of Ultiva™ into not only systemic circulation but also the cerebrospinal fluid. Moreover, the complex pathophysiology might be associated with remifentanil, as well as glycine present in Ultiva™.

Distinct Hypnotic Recoveries After Infusions of Methoxycarbonyl Etomidate and Cyclopropyl Methoxycarbonyl Metomidate: The Role of the Metabolite

BACKGROUND

Methoxycarbonyl etomidate (MOC-etomidate) and cyclopropyl methoxycarbonyl metomidate (CPMM) are rapidly metabolized "soft" etomidate analogs. CPMM's duration of hypnotic effect is context insensitive, whereas MOC-etomidate's is not. In this study, we tested the hypothesis that CPMM's effect is context insensitive because, unlike MOC-etomidate, its metabolite fails to reach physiologically important concentrations in vivo even with prolonged continuous infusion.

METHODS

We compared the potencies with which MOC-etomidate and CPMM activate α1(L264T)β3γ2 γ-aminobutyric acid type A receptors and induce loss-of-righting reflexes (i.e., produce hypnosis) in tadpoles with those of their metabolites (MOC-etomidate's carboxylic acid metabolite [MOC-ECA] and CPMM's carboxylic acid metabolite [CPMM-CA], respectively). We measured metabolite concentrations in the blood and cerebrospinal fluid of Sprague-Dawley rats on CPMM infusion and compared them with those achieved with MOC-etomidate infusion. We measured the rates with which brain tissue from Sprague-Dawley rats metabolize MOC-etomidate and CPMM.

RESULTS

Both analogs and their metabolites enhanced γ-aminobutyric acid type A receptor function and induced loss-of-righting reflexes in a concentration-dependent manner. However, in these 2 assays, CPMM-CA's potency relative to its parent hypnotic was approximately 1:4900 and 1:1900, respectively, whereas MOC-ECA's was only approximately 1:415 and 1:390, respectively. With 2-hour CPMM infusions, CPMM-CA reached respective concentrations in the blood and cerebrospinal fluid that were 2 and >3 orders of magnitude lower than that which produced hypnosis. CPMM was metabolized by the brain tissue at a rate that is approximately 1/15th that of MOC-etomidate.

CONCLUSIONS

Hypnotic recovery after CPMM administration is context insensitive because its metabolite does not accumulate to hypnotic levels in the central nervous system. This reflects the very large potency ratio between CPMM and CPMM-CA and the resistance of CPMM to metabolism by esterases present in the brain.