Intraoperative Remifentanil Infusion Research Articles

Comparison of the effects of intraoperative remifentanil and sufentanil infusion on postoperative pain management in robotic gynecological surgery: a retrospective cohort study.

Remifentanil and sufentanil are potent short-acting synthetic opioid analgesics. The administration of remifentanil has been associated with the incidence of opioid-induced hyperalgesia. Opioid-induced hyperalgesia may be alleviated when opioids, such as morphine, are switched to sufentanil. Therefore, this retrospective observational study aimed to compare the effects of remifentanil and sufentanil on postoperative pain in patients undergoing robotic gynecological surgery. We retrospectively analyzed the electronic medical records of patients who underwent elective robotic gynecological surgery between January 2016 and February 2021. The patients were classified into sufentanil (n = 159) or remifentanil (n = 359) groups according to the opioids administered continuously during anesthesia. The primary outcome assessed in this study was the postoperative pain score measured using the numeric rating scale (NRS). The secondary outcomes assessed included the recovery time (from discontinuation of opioid infusion to extubation) and frequency of rescue analgesic administration in the post-anesthesia care unit (PACU). The recovery time did not differ significantly between the two groups. The NRS score for pain (median [1Q, 3Q]) in the PACU was significantly lower in the sufentanil group than in the remifentanil group (2 [2, 3] vs. 4 [3, 7], P < 0.001). The frequency of rescue analgesic administration in the PACU was 6.3% and 35.4% in the sufentanil and remifentanil groups, respectively (P < 0.001). Sufentanil, as an adjunct to sevoflurane anesthesia is more advantageous than remifentanil in terms of postoperative pain control during robotic gynecological surgery.

The Effects of Intraoperative Remifentanil Infusion on Postoperative Opioid Consumption in Patients Who Underwent Total Knee Arthroplasty with Femoral Nerve Block.

(1) Background: Remifentanil is used for intraoperative pain control; however, it has several side effects, such as hypotension and opioid-induced hyperalgesia. We aimed to determine whether an intraoperative remifentanil infusion may increase postoperative opioid consumption in patients undergoing total knee arthroscopy (TKA) under femoral nerve block (FNB) in addition to general anesthesia. (2) Methods: We randomly assigned 66 patients who underwent total knee arthroplasty to the remifentanil (R) and control (C) groups. All patients underwent FNB and popliteal artery and posterior capsule of the knee (iPACK) block in addition to sevoflurane-based general anesthesia. Postoperative pain control was achieved using intravenous patient-controlled analgesia (IV-PCA) fentanyl. We recorded IV-PCA fentanyl consumption at various postoperative timepoints, numerical rating scale (NRS) scores, intraoperative changes in vital signs and index of nociception (qNOX), ephedrine consumption, postoperative side effects, satisfaction, and sleep quality. (3) Results: The primary outcome (the cumulative IV-PCA fentanyl usage within 48 h postoperatively) was significantly lower in the C group (541.1 ± 294.5 µg) than in the R group (717.5 ± 224.0 µg) (p < 0.001). The secondary outcome (the cumulative IV-PCA fentanyl usage within 12, 24, and 72 h) was lower in the C group than in the R group and the mean arterial pressure was lower in the R group than in the C group from immediately after tourniquet on to immediately after tourniquet off. The heart rate was lower in the R group from immediately after incision to immediately after irrigation. There was no significant between-group difference in the perioperative qNOX and NRS scores at rest and activity except for NRS scores at 72 h postoperatively. Ephedrine use was higher in the R group than in the C group (p = 0.003). There was no significant between-group difference in the incidence of postoperative nausea and vomiting, nor in the postoperative satisfaction and sleep quality. (4) Conclusions: Avoiding intraoperative remifentanil infusion may reduce total opioid consumption in patients undergoing FNB before TKA.

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

BackgroundThe liberal use of remifentanil in spine surgery has been associated with an increased incidence of postoperative hyperalgesia. Nevertheless, controversies remain as the existing evidence is inconclusive to determine the relationship between remifentanil use and the development of opioid-induced hyperalgesia. We hypothesized that intraoperative infusion of higher dose remifentanil during scoliosis surgery is associated with postoperative hyperalgesia, manifesting clinically as greater postoperative morphine consumption and pain scores.MethodsNinety-seven patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion surgery at a single tertiary institution from March 2019 until June 2020 were enrolled in this retrospective study. Anesthesia was maintained using a target-controlled infusion of remifentanil combined with volatile anesthetic desflurane in 92 patients, while five patients received it as part of total intravenous anesthesia. Intravenous ketamine, paracetamol, and fentanyl were administered as multimodal analgesia. All patients received patient-controlled analgesia (PCA) morphine postoperatively. Pain scores at rest and on movement, assessed using the numerical rating scale, and the cumulative PCA morphine consumption were collected at a six-hourly interval for up to 48 h. According to the median intraoperative remifentanil dose usage of 0.215 µg/kg/min, patients were divided into two groups: low dose and high dose group.ResultsThere were no significant differences in the pain score and cumulative PCA morphine consumption between the low and high dose remifentanil group. The mean duration of remifentanil infusion was 134.9 ± 22.0 and 123.4 ± 23.7 min, respectively.ConclusionIntraoperative use of remifentanil as an adjuvant in AIS patients undergoing posterior spinal fusion surgery was not associated with postoperative hyperalgesia.

Nalmefene vs. dexmedetomidine for prevention of postoperative hyperalgesia in patients undergoing laparoscopic gynecological surgery with remifentanil infusion: A randomized double-blind controlled trial.

Intraoperative remifentanil infusion may paradoxically induce post-surgical hyperalgesia. Dexmedetomidine reportedly reduces opioid-induced hyperalgesia. Nalmefene selectively reverses several side-effects of opioids without impairing analgesia. Herein, this randomized, double-blind controlled trial investigated whether nalmefene, dexmedetomidine, and both drugs combined prevent remifentanil-induced hyperalgesia. One hundred and fifty patients undergoing elective laparoscopic gynecological surgery under desflurane anesthesia randomly received either intraoperative sufentanil 0.20μgkg-1 (Group S), or remifentanil 0.20μgkg-1min-1 (Group R), or remifentanil and pre-anesthesia nalmefene 0.20μgkg-1 (Group N), or remifentanil and pre-anesthesia dexmedetomidine 0.50μgkg-1 (Group D), or remifentanil and the combination of dexmedetomidine 0.25μgkg-1 and nalmefene 0.10μgkg-1 (Group DN). The threshold of postoperative mechanical hyperalgesia (primary outcome) was measured with von Frey filaments. We also recorded pain intensity, analgesic consumptions, hyperalgesic area, and side-effects for 24h postoperatively. Compared with Group S, remifentanil reduced hyperalgesic threshold on the forearm [mean 89.4 (SD 13.7) vs. 62.2 (10.7) g, p < 0.001] at postoperative 24h. Pain threshold on the forearm at postoperative 24h was significantly lower in Group R than in Groups N, D and DN [62.2 (10.7) vs. 71.1 (12.3), 72.4 (12.9) and 78.0 (13.8)g]. Compared with Group R, Postoperative pain intensity, analgesic consumption and hyperalgesic area were lower likewise in Groups D and DN. However, the incidence of intraoperative bradycardia was lower and post-anesthesia recovery time was shorter in Group DN than Group D. Preoperative therapy of dexmedetomidine and nalmefene combined attenuates postoperative hyperalgesia in patients undergoing laparoscopic gynecological surgery under desflurane-remifentanil anesthesia.

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

Remifentanil is useful in balanced anesthesia; however, there is concern regarding opioid-induced hyperalgesia. The effect of remifentanil on rebound pain, characterized by hyperalgesia after peripheral nerve block has rarely been studied. This study evaluated whether intraoperative remifentanil infusion may increase postoperative analgesic requirement in patients receiving preoperative interscalene brachial plexus block (IBP). Sixty-eight patients undergoing arthroscopic shoulder surgery under general anesthesia were randomly allocated to remifentanil (R) or control (C) group. Preoperative IBP with 0.5% ropivacaine 15mL was performed in all patients. Intraoperative remifentanil was administered only in the R group. Postoperative pain was controlled using intravenous patient-controlled analgesia (IV-PCA) and rescue analgesics. The primary outcome was the dosage of fentanyl-nefopam IV-PCA infused over 24h postoperatively. The secondary outcomes included the numeric rating scale (NRS) score recorded at 4-h intervals over 24h, amount of rescue analgesics and total postoperative analgesics used over 24h, occurrence of intraoperative hypotension, postoperative nausea and vomiting (PONV) and delirium. The dosage of fentanyl-nefopam IV-PCA was significantly less in C group than R group for postoperative 24h. Fentanyl 101 [63-158] (median [interquartile range]) µg was used in the C group, while fentanyl 161 [103-285] µg was used in the R group (median difference 64µg, 95% CI 10-121µg, P = 0.02). Nefopam 8.1 [5.0-12.6] mg was used in the C group, while nefopam 12.9 [8.2-22.8] mg was used in the R group (median difference 5.1mg, 95% CI 0.8-9.7mg, P = 0.02). The total analgesic consumption: the sum of PCA consumption and administered rescue analgesic dose, converted to morphine milligram equivalents, was higher in the R group than C group (median difference 10.9mg, 95% CI 3.0-19.0mg, P = 0.01). The average NRS score, the incidence of PONV and delirium, were similar in both groups. The incidence of intraoperative hypotension was higher in R group than C group (47.1% vs. 20.6%, P = 0.005). Remifentanil administration during arthroscopic shoulder surgery in patients undergoing preoperative IBP increased postoperative analgesic consumption.

Is intraoperative remifentanil infusion associated with early postoperative hypertension in intracranial tumor surgery?

Hemodynamic instability may cause serious complications such as intracranial hemorrhage, stroke, and brain edema in the postoperative period in intracranial tumor surgery. This study investigated the relationship between remifentanil infusion used for anesthesia maintenance in intracranial tumor surgery and postoperative early hypertension. Hemodynamic parameters were recorded in the first 24 hours after intracranial tumor surgery in the postoperative intensive care unit. Hypertension rate, causes, and treatment methods of hypertension in our clinic were compared with the literature. The study included 113 patients. In 83 patients (73.4%), hypertension was detected in the first 24-hour period during the intensive care follow-up. The hypertensive attack was controlled with intravenous opioids administered in 69 (83.1%) of 83 patients with hypertension, and with additional intravenous antihypertensive in 14 (16.9%) patients. Analgesia use was higher in hypertensive patients in the first 24 hours postoperatively (83.1% vs. 30%, P&lt;.01). Ultra-short-acting remifentanil infusion used for maintenance of anesthesia may cause hypertensive episodes in the early postoperative period.

Opioid-free anesthesia versus opioid-inclusive anesthesia for breast cancer surgery: a retrospective study

BackgroundBreast cancer surgery is usually managed using opioid-inclusive anesthesia (OIA), although opioids are associated with several adverse events, including nausea, vomiting, and constipation. Multimodal opioid-free anesthesia (OFA) has been introduced to reduce the incidence of these side effects. In this single-center retrospective study, we investigated whether ketamine, combined with magnesium and clonidine, could effectively control postoperative pain in patients undergoing quadrantectomy, while reducing postoperative nausea and vomiting (PONV).ResultsA total of 89 patients submitted to quadrantectomy were included and divided into an OFA group (38 patients) and an OIA group (51 patients) according to the received anesthetic technique. Analgesia in the OIA group was based on an intraoperative infusion of remifentanil, and analgesia in the OFA consisted of an intraoperative infusion of ketamine and magnesium sulfate. Postoperative pain in both groups was managed with nonsteroidal anti-inflammatory drugs (NSAIDs) and paracetamol. Postoperative pain, assessed with the numeric rating scale (NRS), requirements for additional analgesics, the incidence of PONV, and patient satisfaction evaluated using a QoR-40 questionnaire were compared between the two groups. Levels of pain at 30 min and 6, 12, and 24 h after surgery; number of paracetamol rescue doses; and the incidence of PONV were lower in the OFA group (p <0.05). Patient satisfaction was comparable in the two groups.ConclusionsA combination of ketamine, magnesium, and clonidine could be more effective than opioid-based analgesia in reducing postoperative pain and lowering PONV occurrence after quadrantectomy for breast cancer.

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

Our aim was to describe the long-term prevalence, risk factors and impact on quality of life of persistent postsurgical pain (PPP) following cardiac surgery. All patients undergoing sternotomy in a single centre over 6months were prospectively interviewed by telephone at six months and seven years following surgery. We analysed data from 174 patients at six months and 146 patients at seven years following surgery, revealing a PPP prevalence of 39.7% (n = 69) and 9.6% (n = 14) respectively. At six post-operative months, younger age, higher acute pain score, intraoperative remifentanil infusion and more prolonged surgery were associated with sternotomy-site PPP. These variables, in combination, predict PPP in this study group with area under the receiver operating curve of 0.91 (95% CI 0.86-0.94) at 6months and 0.74 (95% CI 0.57-0.86) at 7years. Quality of life scores were significantly lower with PPP (median change in EQ-5D score=-0.23 [-0.57, -0.09] compared to 0.00 [0-0.24] without PPP at 7years, p<0.001). At7 years, younger age, prolonged surgery and intraoperative remifentanil infusion were associated with sternotomy-site PPP. To the best of our knowledge, this is the longest follow-up of PPP across all surgical specialities and certainly within cardiac surgery. Prevalence of PPP and impact on QOL after cardiac surgery are high and associated with young age, high acute pain score, use of remifentanil and long operative time. We present a predictive score to highlight patients at risk of developing PPP. Seven years after cardiac surgery, almost 10% of patients in this cohort described persistent pain in and around the incision. While higher than previous reports in the literature (limited to up to five post-operative years), this assessment was made following three maximal coughs and therefore is movement or function evoked. High incident of persistent postsurgical pain may adversely affect long-term quality of life which is measured using a validated tool.

Comparison of analgesic efficacy between rectus sheath blockade, intrathecal morphine with bupivacaine, and intravenous patient-controlled analgesia in patients undergoing robot-assisted laparoscopic prostatectomy: a prospective, observational clinical study

BackgroundWe explored the analgesic outcomes on postoperative day (POD) 1 in patients undergoing robot-assisted laparoscopic prostatectomy (RALP) who received intravenous patient-controlled analgesia (IV-PCA), rectus sheath bupivacaine block (RSB), or intrathecal morphine with bupivacaine block (ITMB).MethodsThis was a prospective, observational clinical trial. Patients were divided into three groups: IV-PCA (n = 30), RSB (n = 30), and ITMB (n = 30). Peak pain scores at rest and with coughing, cumulative IV-PCA drug consumption, the need for IV rescue opioids, and Quality of Recovery-15 (QoR-15) questionnaire scores collected on POD 1 were compared among the groups.ResultsThe preoperative and intraoperative findings were comparable among the groups; the ITMB group required the least remifentanil of all groups. During POD 1, the ITMB group reported lower levels of pain at rest and with coughing, compared with the other two groups. During POD 1, incidences of severe pain at rest (10.0% vs. 23.3% vs. 40.0%) and with coughing (16.7% vs. 36.7% vs. 66.7%) were the lowest in the ITMB group compared with the RSB and IV-PCA groups, respectively. After adjustment for age, body mass index, diabetes mellitus, hypertension, and intraoperative remifentanil infusion, severe pain at rest was 0.167-fold less common in the ITMB group than in the IV-PCA group, while pain with coughing was 0.1-fold lower in the ITMB group and 0.306-fold lower in the RSB group, compared with the IV-PCA group. The ITMB group required lower cumulative IV-PCA drug infusions and less IV rescue opioids, while exhibiting a better QoR-15 global score, compared with the other two groups. Complications (nausea and pruritus) were significantly more common in the ITMB group than in the other two groups; however, we noted no ITMB- or RSB-related anesthetic complications (respiratory depression, post-dural headache, nerve injury, or puncture site hematoma or infection), and all patients were assessed as Clavien-Dindo grade I or II during the hospital stay.ConclusionAlthough ITMB induced complications of nausea and pruritus, this analgesic technique provided appropriate pain relief that enhanced patient perception related to early postoperative recovery.Trial registrationClinical Research Information Service, Republic of Korea, (approval number: KCT0005040) on May 20, 2020

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

Report of secondary pain outcomes from a prospective, randomized, open-label clinical trial that compared remifentanil and fentanyl on perioperative hyperglycemic response in cardiac surgery. Single institution, tertiary university hospital. The study comprised 116 adult elective cardiac surgical patients. Participants were randomly assigned to receive either intermittent fentanyl boluses (F) or continuous remifentanil infusion (R) intraoperatively. Postoperative pain was evaluated with pain scores every 6 hours for 48 hours. Pain threshold to mechanical stimuli was measured around the sternotomy incision at 48 and 96 hours. The development of chronic pain was assessed using the numeric rating scale at 1, 3, 6, and 12 months after discharge. The final analysis included 106 patients. Pain scores and wound hyperalgesia were not significantly different postoperatively between the groups. The incidence of chronic pain at 3 months was comparable in both groups (61% in group F v 58% in group R; p = 0.79). Pain of more-than-mild degree was seen in 13 (32%) patients in group F and 8 (19%) in group R (p = 0.25) at 3 months. Median pain scores were not significantly different between the groups at 1, 3, 6, and 12 months after discharge from the hospital. The present study's findings suggested that intraoperative remifentanil infusion does not significantly worsen pain outcomes in patients undergoing elective cardiac surgery.

Acceptance of a propofol and remifentanil infusion dosing algorithm to optimize postoperative emergence and analgesia.

We implemented a pharmacokinetic/pharmacodynamic (PK/PD) based optimization algorithm recommending intraoperative Remifentanil and Propofol infusion rates to minimize time to emergence and maximize the duration of analgesia in a clinical setting. This feasibility study tested the clinical acceptance of the optimization algorithm's recommendations during scoliosis surgical repair for 14 patients. Anesthesiologist accepted 359/394 (91%) of the recommendations given on the basis of the optimization algorithm. While following the optimization's recommendations the anesthesiologist decreased Propofol infusions from an average of 164-135mcg/kg/min [p = 0.002] and increased Remifentanil infusions from an average of 0.22-0.30mcg/kg/min [p = 0.004]. The anesthesiologists appeared to accept and follow the recommendations from a PK/PD based optimization algorithm.

Optimizing intraoperative administration of propofol, remifentanil, and fentanyl through pharmacokinetic and pharmacodynamic simulations to increase the postoperative duration of analgesia.

Titrating an intraoperative anesthetic to achieve the postoperative goals of rapid emergence and prolonged analgesia can be difficult because of inter-patient variability and the need to provide intraoperative sedation and analgesia. Modeling pharmacokinetics and pharmacodynamics of anesthetic administrations estimates drug concentrations and predicted responses to stimuli during anesthesia. With utility of these PK/PD models we created an algorithm to optimize the intraoperative dosing regimen. We hypothesized the optimization algorithm would find a dosing regimen that would increase the postoperative duration of analgesia, not increase the time to emergence, and meet the intraoperative requirements of sedation and analgesia. To evaluate these hypotheses we performed a simulation study on previously collected anesthesia data. We developed an algorithm to recommend different intraoperative dosing regimens for improved post-operative results. To test the post-operative results of the algorithm we tested it on previously collected anesthesia data. An anesthetic dataset of 21 patients was obtained from a previous study from an anesthetic database at the University of Utah. Using the anesthetic records from these surgeries we modeled 21 patients using the same patient demographics and anesthetic requirements as the dataset. The anesthetic was simulated for each of the 21 patients with three different dosing regimens. The three dosing regimens are: from the anesthesiologist as recorded in the dataset (control group), from the algorithm in the clinical scenario one (test group), and from the algorithm in the clinical scenario two (test group). We created two clinical scenarios for the optimization algorithm to perform; one with normal general anesthesia constraints and goals, and a second condition where a delayed time to emergence is allowed to further maximize the duration of analgesia. The algorithm was evaluated by comparing the post-operative results of the control group to each of the test groups. Comparing results between the clinical scenario 1 dosing to the actual dosing showed a median increase in the duration of analgesia by 6min and the time to emergence by 0.3min. This was achieved by decreasing the intraoperative remifentanil infusion rate, increased the fentanyl dosing regimen, and not changing the propofol infusion rate. Comparing results between the clinical scenario 2 dosing to the actual dosing showed a median increase in the duration of analgesia by 26min and emergence by 1.5min. To dosing regimen from clinical scenario 2 greatly increased the fentanyl dosing regimen and greatly decreased the remifentanil infusion rate with no change to the propofol infusion rate. The results from this preliminary analysis of the optimization algorithm appear to imply that it can operate as intended. However a clinical study is warranted to determine to what extent the optimization algorithm determined optimal dosing regimens can maximize the postoperative duration of analgesia without delaying the time to emergence in a clinical setting.

High-dose intraoperative remifentanil infusion increases early postoperative analgesic consumption: a prospective, randomized, double-blind controlled study.

The purpose of this study was to determine whether intraoperative infusion of remifentanil induces acute tolerance to opioids, and compare the postoperative pain and opioid consumption by the effect site concentrations of remifentanil. One hundred and ninety-eight patients undergoing gastrectomy were randomly assigned to maintain target effect site concentrations of remifentanil at 0 (Group 1, n = 39), 2 (Group 2, n = 40), 4 (Group 3, n = 39), 8 (Group 4, n = 40), or 12ng/ml (Group 5, n = 40) during operation. Postoperative pain intensities and fentanyl requirement were recorded at postoperative 2, 6, 24, and 48h. Fentanyl requirement for postoperative 2h was significantly greater in Group 5 compared to Group 1 (376 ± 116 vs. 283 ± 129µg, P = 0.03). However, there were no differences in fentanyl requirements among the groups after postoperative 2h. Also, total fentanyl consumption for 48h was similar in all groups (Group 1; 3106 ± 629, Group 2; 2970 ± 705, Group 3; 3017 ± 555, Group 4; 3151 ± 606, and Group 5; 2984 ± 443 µg, P = 0.717). Pain scores at rest and during deep breathing were comparable in all groups at the time of each examination. Intraoperative infusion of remifentanil with 12ng/ml of effect site concentration in patients undergoing gastrectomy increases early postoperative fentanyl requirement. Acute opioid tolerance would be developed by higher concentration of remifentanil than dosage of common anesthetic practice.

Attenuation of Remifentanil-Induced Hyperalgesia by Betulinic Acid Associates with Inhibiting Oxidative Stress and Inflammation in Spinal Dorsal Horn

Remifentanil-induced hyperalgesia (RIH) is known to be associated with oxidative stress and inflammation. Betulinic acid (BA) was reported to reduce visceral pain owing to its anti-oxidative and anti-inflammatory potential. Here, we ­explored whether BA can attenuate RIH through inhibiting oxidative stress and inflammation in spinal dorsal horn. Sprague-Dawley rats were randomly divided into 4 groups: Control, Incision, RIH, and RIH pre-treated with BA. After pretreated with BA (25 mg/kg, i.g.) for 7 days, rats were subcutaneously infused with remifentanil (40 μg/kg) for 30 min during right plantar incision surgery to induce RIH. The paw withdrawal mechanical threshold (PWMT), paw withdrawal thermal latency (PWTL), spinal oxidative stress and inflammatory mediators were determined. Intraoperative remifentanil infusion induced postoperative hyperalgesia, as evidenced by the significant decrease in PWMT and PWTL (p < 0.01), and the significant increase in oxidative stress and inflammation evidenced by up-regulations of malondialdehyde, 3-nitrotyrosine, interleukin-1β and tumour necrosis factor-α (p < 0.01) in spinal dorsal horn and matrix metalloproteinase-9 (MMP-9) activity (p < 0.01) in dorsal root ganglion, as well as a decrease in manganese superoxide ­dismutase activity (p < 0.01) compared with control and ­incision groups. All these results mentioned above were markedly reversed by pre-treatment with BA (p < 0.01) compared with RIH group. These findings demonstrated that BA can effectively attenuate RIH, which associates with potentially inhibiting oxidative stress and subsequently down-regulating MMP-9-related pro-inflammatory cyokines in spinal dorsal horn.

Effects of remifentanil maintenance during recovery on emergence delirium in children with sevoflurane anesthesia.

Emergence delirium is a common complication of sevoflurane anesthesia in children. We examined the effects of maintaining remifentanil infusion during the recovery period on the incidence of emergence delirium in preschool-age children undergoing strabismus surgery under sevoflurane anesthesia. Eighty children (aged 3-7years) were randomly assigned to either the control group (group C; intraoperative remifentanil infusion) or the intervention group (group R; intraoperative remifentanil infusion followed by remifentanil maintenance during the recovery phase). Intraoperative remifentanil infusion (0.2μg/kg/min) was discontinued upon surgery completion in the group C, and was maintained until the discharge criteria were met at a dose of 0.05μg/kg/min in the group R. The incidence of emergence delirium was assessed using a five-point agitation scale and the Pediatric Anesthesia Emergence Delirium scale after arrival in the postanesthesia care unit. Postoperative pain was assessed using the Children's Hospital of Eastern Ontario Pain Scale. The incidence of emergence delirium according to the five-point agitation scale (scores≥4) was lower in the group R (33.3%) compared to the group C (68.3%) (odds ratio 0.206; 95% CI 0.080 to 0.531; P=0.002). Similar results were obtained using the Pediatric Anesthesia Emergence Delirium scale (scores>12), with an incidence of 5.1% in the group R and 34.0% in the control group (odds ratio 0.104; 95% CI 0.022 to 0.497; P=0.001). The Children's Hospital of Eastern Ontario Pain Scale scores and occurrence of postoperative adverse events including laryngospasm, desaturation, nausea, and vomiting were similar between the two groups. Maintaining a low dose of remifentanil (0.05μg/kg/min) throughout the recovery phase attenuated the incidence of emergence delirium in children undergoing strabismus surgery under sevoflurane anesthesia.

Comparative analysis of remifentanil versus dexmedetomidine in the incidence of pain in a post-anesthesia care unit after bariatric surgery

ABSTRACT BACKGROUND AND OBJECTIVES: Compare anesthesia techniques with sufentanil and intraoperative infusion of remifentanil or dexmedetomidine, and to then analyze their associations with the incidence of pain and other complications in the post-anesthesia care unit. METHODS: A retrospective analytical observational study conducted in a reference center for bariatric surgery in Sao Paulo, Sao Paulo State, Brazil. Patients (n=120) included in the study were randomly selected using this site’s anesthesia records for bariatric surgery. Four 30-patient groups were established: G1 - induction with 0.5 µg.kg-1 sufentanil associated with the continuous infusion of remifentanil; G2 - induction with 0.7 µg.kg-1 sufentanil associated with the continuous infusion of remifentanil; G3 - induction with 0.5 µg.kg-1 sufentanil associated with the continuous infusion of dexmedetomidine; and G4 - induction with 0.7 µg.kg-1 sufentanil associated with the continuous infusion of dexmedetomidine. Significance was set at p G3=G4; p<0.05). The occurrence of respiratory complications did not differ significantly between the groups. CONCLUSION: The use of dexmedetomidine proved to be better for analgesia in the post-anesthesia care unit, and it did not increase the risk of respiratory complications when compared to the continuous infusion of remifentanil, regardless of the sufentanil dose used for induction.

Effect of remifentanil on the recovery profile after head and neck surgeries: A prospective study

Background and Aims:Development of opioid tolerance in the perioperative period due to remifentanil remains controversial. We evaluated occurrence of opioid tolerance and other adverse effects due to remifentanil in patients undergoing head and neck surgery.Material and Methods:We recruited adult participants with ASA status I to III who received general anesthesia for approximately 2 h for elective head and neck procedures. Remifentanil infusion was used in one group and intermittent boluses of morphine or fentanyl were administered in another group. Postoperative pain was treated with intermittent boluses of morphine and fentanyl in post-anaesthesia care unit (PACU) to achieve a numerical rating scale score of 3. Opioid requirement was assessed as an indicator of opioid tolerance. Patients were also evaluated for time to discharge from PACU.Results:We studied 222 adults aged between 21 and 80 years. One hundred and eleven patients received a combination of remifentanil infusion and morphine boluses, and another 111 patients received only fentanyl and/or morphine boluses intraoperatively. Fifty-one patients in the remifentanil group and 25 in the fentanyl/morphine group required opioids in the PACU. Opioid requirement were significantly more (mean ± SD, 44.98 ± 59.7 Vs 20.23 ± 46.66 mcg.kg−1; P = 0.001) and required longer time to discharge from PACU in the remifentanil group compared to the fentanyl/morphine group (Mean ± SD, 88.6 ± 39.5 min Vs 73.1 ± 38.4 min; P < 0.001). No difference in the incidence of adverse effects in two groups was noted.Conclusion:At clinically relevant doses, intraoperative remifentanil infusion appears to increase opioid consumption in the immediate postoperative period. This can result in delayed discharge from PACU for patients undergoing elective head and neck procedures.

Analgesia nociception index (ani) monitoring in patients with thoracic paravertebral block: a randomized controlled study.

The goal of the study was to evaluate the effectiveness of analgesia nociception index (ANI) monitoring during intraoperative period for patients with thoracic paravertebral block (TPVB) undergoing breast surgery under general anesthesia. This prospective randomized trial was performed after receiving ethics committee approval in 44 patients who were scheduled to undergo breast surgery under general anesthesia. TPVB was performed in the preoperative period using 20mL of bupivacaine 0.25% at T4 level. Anesthesia maintenance was provided with sevoflurane in O2: air mixture and remifentanil infusion. Intraoperative concentration of sevoflurane was adjusted according to BIS monitoring keeping the values between 40-60. In a randomized manner patients were divided into two groups. In Group control (n:22) intraoperative remifentanil infusion rate was regulated according to hemodynamic parameters, in Group ANI (n:22) remifentanil infusion rate was titrated to keep ANI monitoring values between 50-70. Total remifentanil consumption was recorded as micrograms. Demographic data, anesthesia and surgery time, intraoperative hemodynamic parameters, post-anesthesia recovery time and requirement of additional analgesic in the recovery drug were recorded. There were no significant difference in demographic data, intraoperative hemodynamic parameters, post-anesthesia recovery time and requirement of additional analgesic drug. There was a statistically significant difference between groups in total remifentanil consumption (Group ANI: 629.6 ± 422.4mcg, Group control: 965.2 ± 543.6mcg) (p = 0.027). In patients under general anesthesia ANI monitorisation can help optimisation of opioid consumption and provide data about nociception/antinociception intraoperatively but further experimental and clinical trials in a large scale are needed.

Remifentanil Tolerance and Hyperalgesia

Summary The unique pharmacology of remifentanil makes it a popular intra-operative analgesic. Short-acting opioids like remifentanil have been associated with acute opioid tolerance and/or opioid-induced hyperalgesia, two phenomena which have different mechanisms and are pharmacologically distinct. Clinical studies show heterogeneity of remifentanil infusion regimens, durations of infusion, maintenance of anaesthesia, cumulative dose of remifentanil and pain measures, which makes it difficult to draw conclusions about the incidence of acute tolerance or hyperalgesia. However, it appears that intra-operative remifentanil infusion rates of above 0.25 μg.kg−1.min−1 are associated with higher postoperative opioid consumption, suggesting tolerance. Infusion rates greater than 0.2 μg.kg−1.min−1 are characterised by lower mechanical/pressure/cold/pain thresholds, which suggests hyperalgesia. The use of concurrent multimodal analgesia, especially N-methyl-D-aspartate receptor antagonists, may be an effective preventive strategy. The clinical significance and long-term consequences of these entities is still uncertain.

Remifentanil tolerance and hyperalgesia: short-term gain, long-term pain?

The unique pharmacology of remifentanil makes it a popular intra-operative analgesic. Short-acting opioids like remifentanil have been associated with acute opioid tolerance and/or opioid-induced hyperalgesia, two phenomena which have different mechanisms and are pharmacologically distinct. Clinical studies show heterogeneity of remifentanil infusion regimens, durations of infusion, maintenance of anaesthesia, cumulative dose of remifentanil and pain measures, which makes it difficult to draw conclusions about the incidence of acute tolerance or hyperalgesia. However, it appears that intra-operative remifentanil infusion rates of above 0.25μg.kg-1 .min-1 are associated with higher postoperative opioid consumption, suggesting tolerance. Infusion rates greater than 0.2μg.kg-1 .min-1 are characterised by lower mechanical/pressure/cold/pain thresholds, which suggests hyperalgesia. The use of concurrent multimodal analgesia, especially N-methyl-D-aspartate receptor antagonists, may be an effective preventive strategy. The clinical significance and long-term consequences of these entities is still uncertain.