Nociception Monitoring Research Articles

Progress in the validation of nociception monitoring in guiding intraoperative analgesic therapy.

This article summarizes the current level of validation for several nociception monitors using a categorized validation process to facilitate the comparison of performance. Nociception monitors improve the detection of a shift in the nociception and antinociception balance during anesthesia, guiding perioperative analgesic therapy. A clear overview and comparison of the validation process for these monitors is missing. Within a 2-year time-frame, we identified validation studies for four monitors [analgesia nociception index (ANI), nociception level monitor (NOL), surgical pleth index (SPI), and pupillometry]. We categorized these studies in one out of six mandatory validation steps: developmental studies, clinical validation studies, pharmacological validation studies, clinical utility studies, outcome improvement studies and economical evaluation studies. The current level of validation for most monitors is mainly focused on the first three categories, whereas ANI, NOL, and SPI advanced most in the availability of clinical utility studies and provide confirmation of a clinical outcome improvement. Analysis of economical value for public health effects is not yet publicly available for the studied monitors. This review proposes a stepwise structure for validation of new monitoring technology, which facilitates comparison between the level of validation of different devices and identifies the need for future research questions.

Evaluation of the Surgical Pleth Index (SPI) for the monitoring of the nociception-antinociception balance in dogs undergoing castration: A prospective clinical trial

The aim of this prospective clinical study was to evaluate the efficacy of the Surgical Pleth Index (SPI), a validated nociception monitor in human anaesthesia, in dogs. The technology uses a plethysmographic signal from a specific pulse oximetry probe to analyse pulse wave amplitudes and heartbeat intervals. Twenty-six healthy dogs anaesthetised for castration were included. SPI, invasive mean arterial pressure (MAP) and heart rate (HR) were continuously monitored. The occurrence or resolution of a haemodynamic reaction (HDR), defined as a > 20% increase in HR and/or MAP, was assessed at predefined times: cutaneous incision, testicles' exteriorization, cutaneous suture, and fentanyl administration. Following nociceptive events, the dogs presenting a HDR showed a significant 8% and 10% increase in SPI at 3 and 5 min respectively, whereas after fentanyl administration, a 13% and 16% significant decrease in SPI were noted. Receiver operating characteristic curves analysis indicated a moderate performance for the dynamic variations of SPI over 1 min to predict a HDR (AUC: 0.68, threshold value: +15%) or its resolution after fentanyl administration (AUC of 0.72, threshold value: −15%) within 3 min. The SPI varied according to perioperative nociceptive events and analgesic treatment; however, its performance to anticipate a HDR was limited with high specificity but low sensivity. Refinement of the algorithm to specifically accommodate for the canine species may be warranted. Further studies are required to evaluate the influence of other factors on the performance of this index.

Nociception monitoring using the Surgical Pleth Index in anaesthetized dogs

Nociception monitoring using the Surgical Pleth Index in anaesthetized dogs

Effects of anesthetics on nociceptive sensory evoked potentials by intraepidermal noxious electrical stimulation of A-δ fibers.

Generation of nociceptive sensory evoked potentials (NEPs) by selective stimulation of nociceptive intraepidermal nerve fibers is a simple technique which could be used as intraoperative nociception monitor. We evaluated the effects of remifentanil, propofol and sevoflurane on NEPs by this technique. Patients undergoing general anesthesia were assigned to groups in two studies. A-δ fiber selective NEPs were recorded. Study 1: NEPs were recorded at control, under anesthetics administration: remifentanil at an effect-site concentration (Ce) of 1.0ng/mL (n = 10), propofol at Ce of 0.5µg/mL (n = 10), or sevoflurane at 0.2 minimum alveolar concentration (MAC) (n = 10), and recovery from the anesthetics. Study 2: NEPs were recorded at control and under administration of higher dose anesthetics: propofol at Ce of 0.5 and 1.0µg/mL (n = 10) or sevoflurane at 0.2 and 0.5 MAC (n = 10). A P-value < 0.016 was considered statistically significant in multiple analyses. Study 1: Remifentanil at Ce of 1.0ng/mL significantly suppressed the amplitude of NEPs (mean amplitude (standard deviation) of control vs. remifentanil administration: 16.8µV (3.8) vs. 10.1µV (2.5), P < 0.001). Propofol and sevoflurane did not suppress the amplitude significantly. Study 2: Propofol at Ce of 0.5 and 1.0µg/mL and sevoflurane at 0.2 and 0.5 MAC did not suppress the amplitude significantly. The amplitude of A-δ fiber selective NEPs was suppressed by remifentanil but not propofol or sevoflurane. NEPs with intraepidermal electrical stimulation can assess the analgesic effect of anesthetics. UMIN000038214 REGISTRY URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043328.

Effect of analgesia nociception index monitor-based nociception control on perioperative stress responses during laparoscopic surgery in Trendelenburg position: a randomized controlled trial.

The analgesia nociception index (ANI) monitor is a nociception monitoring device based on heart rate variability. We aimed to determine the effect of ANI monitor-based intraoperative nociception control on the perioperative stress response during laparoscopic surgery in the Trendelenburg position. Altogether, 72 female patients who underwent total laparoscopic hysterectomy were randomized to either the control or ANI group. Intraoperative nociception was controlled by remifentanil administration in a conventional manner (based on blood pressure and heart rate) in the control group and by ANI monitoring in the ANI group. Perioperative stress responses were estimated by measuring the levels of serum catecholamines and catabolic stress hormones at three timepoints: after loss of consciousness, at the end of surgery, and 1 h after the end of surgery. The serum cortisol level at the end of surgery was significantly higher in the ANI group than in the control group (p < 0.001), although more remifentanil was administered in the ANI group than in the control group (p < 0.001). Changes in the other estimators' levels were comparable between groups during the perioperative period. The hemodynamic profiles during surgery were also significantly different between the two groups. Phenylephrine use to treat hypotension was more common in the ANI group than in the control group (p = 0.005). However, postoperative clinical outcomes such as pain and nausea/vomiting did not differ between groups. ANI monitor-based nociception control in laparoscopic surgery in the Trendelenburg position did not improve perioperative stress responses, intraoperative opioid consumption, or postoperative clinical outcomes.Clinical trial registration: ClinicalTrials.gov (NCT04343638).

Generalizability of nociception level as a measure of intraoperative nociceptive stimulation: A retrospective analysis.

Nociception-guided intraoperative opioid administration might help reduce postoperative pain. A commonly used and validated nociception monitor system is nociception level (NOL), which provides the nociception index, ranging from 0 to 100, with 0 representing no nociception and 100 representing extreme nociception. We tested the hypothesis that NOL responses are similar in men and women given remifentanil and fentanyl, across various types of anesthesia, as a function of American Society of Anesthesiologists physical status designations, and over a range of ages and body morphologies. We conducted a retrospective cohort analysis of trial data from eight prospective NOL validation studies. Among 522 noncardiac surgical patients enrolled in these studies, 447 were included in our analysis. We assessed NOL responses to various noxious and non-noxious stimuli. The average NOL in response to 315 noxious stimuli was 47 ± 15 (95% CI = 45-49). The average NOL in response to 361 non-noxious stimuli was 10 ± 12 (95% CI = 9-11). NOL responses were similar in men and women, in patients given remifentanil and fentanyl, across various types of anesthesia, as a function of American Society of Anesthesiologists physical status designations, and over a range of ages and body morphologies. Nociception level appears to provide accurate estimates of intraoperative nociception over a broad range of patients and anesthetic conditions.

Surgical pleth index monitoring in perioperative pain management: usefulness and limitations.

Surgical pleth index (SPI) monitoring is a representative, objective nociception-monitoring device that measures nociception using photoplethysmographic signals. It is easy to apply to patients and the numerical calculation formula is intuitively easy to understand; therefore, its clinical interpretation is simple. Several studies have demonstrated its efficacy and utility. Compared with hemodynamic parameters, the SPI can detect the degree of nociception during surgery under general anesthesia with greater accuracy, and therefore can provide better guidance for the administration of various opioids, including remifentanil, fentanyl, and sufentanil. Indeed, SPI-guided analgesia is associated with lower intraoperative opioid consumption, faster patient recovery, and comparable or lower levels of postoperative pain and rates of adverse events compared with conventional analgesia. In addition, SPI monitoring allows for the degree of postoperative pain and analgesic requirements to be predicted through the SPI values immediately before patient arousal. However, because patient age, effective circulating volume, position, concomitant medication and anesthetic regimen and level of consciousness may be confounding factors in SPI monitoring, clinicians must be careful when interpreting SPI values. In addition, as SPI values can differ depending on anesthetic and analgesic regimens and the underlying disease, an awareness of the effects of these variables with an understanding of the advantages and disadvantages of SPI monitoring compared to other nociception monitoring devices is essential. Therefore, this review aimed to help clinicians perform optimal SPI-guided analgesia and to assist with the establishment of future research designs through clarifying current usefulness and limitations of SPI monitoring in perioperative pain management.

Real-time evaluation of the independent analgesic efficacy of dexmedetomidine

BackgroundDexmedetomidine has analgesic properties, but the intraoperative analgesic effect of dexmedetomidine is often masked by the effects of other general anaesthetics. Therefore, the degree to which it reduces intraoperative pain intensity remains unclear. The objective of this double-blind, randomised controlled trial was to evaluate the independent intraoperative analgesic efficacy of dexmedetomidine in real-time.MethodsThis single-centre study enrolled 181 patients who were hospitalised for below-knee orthopaedic surgeries between 19 January 2021 to 3 August 2021 were eligible for this is single-centre study. Peripheral neural block was performed on patients scheduled for below-knee orthopaedic surgeries. Patients were randomly assigned to the dexmedetomidine or midazolam group and were intravenously administered with 1.5 µg kg−1 h−1 dexmedetomidine or 50 µg kg−1 h−1 midazolam, respectively. The analgesic efficacy was evaluated using the real-time non-invasive nociception monitoring. The primary endpoint was the attainment rate of the nociception index target. The secondary endpoints included the occurrence of intraoperative hypoxemia, haemodynamic parameters, the consciousness index, electromyography and patient outcomes.ResultsOn Kaplan–Meier survival analysis, the defined nociception index target was attained in 95.45% and 40.91% of patients receiving dexmedetomidine and midazolam, respectively. Log-rank analysis revealed that the dexmedetomidine group attained the nociception index target significantly faster and the median attainment time of the nociception index target in the dexmedetomidine group was 15 min. Dexmedetomidine group was associated with a significantly lower incidence of hypoxemia. There was no significant difference in blood pressure between the dexmedetomidine and midazolam groups. Further, the dexmedetomidine group had a lower maximum visual analogue scale score and lower analgesic consumption postoperatively.ConclusionsDexmedetomidine has independent analgesia and systemically administered as an adjuvant agent has better analgesic efficacy than midazolam without severe side effects.Trial registrationclinicaltrial.gov Registry Identifier: NCT-04675372.Registered on 19/12 /2020.

Nociception level response to calibrated stimulations in children: First assessment of the nociception level index in pediatric anesthesia

IntroductionIntraoperative monitoring of nociception has made great progress in adult anesthesia. However, pediatric data are scarce. The Nociception Level (NOL) is one of the most recent indexes of nociception. Its originality is that it provides a multiparametric assessment of nociception. In adults, NOL monitoring allowed lower perioperative opioid requirements, hemodynamic stability, and qualitative postoperative analgesia. So far, the NOL has never been used in children. Our objective was to validate the ability of NOL to provide a quantitative assessment of nociception in anesthetized children. MethodsIn 5–12 years old children anesthetized with sevoflurane and alfentanil (10 µg kg−1), before surgical incision, we performed three standardized tetanic stimulations (5 s, 100 Hz) of different intensities (10−30–60 mA) in a randomized order. NOL, heart rate, blood pressure and Analgesia-Nociception Index variations were assessed after each stimulation. ResultsThirty children were included. Data were analyzed with a covariance pattern linear mixed regression model. NOL increased after the stimulations (p < 0.05 at each intensity). NOL response was influenced by stimulation intensity (p < 0.001). Heart rate and blood pressure were barely modified by the stimulations. Analgesia-Nociception Index decreased after the stimulations (p < 0.001 at each intensity). Analgesia-Nociception index response was not influenced by stimulation intensity (p = 0.064). NOL and Analgesia-Nociception Index responses were significantly correlated (Pearson r = 0.47; p < 0.001). ConclusionsNOL allows a quantitative assessment of nociception under anesthesia in 5–12 years-old children. This study provides a solid basis for all future investigations on NOL monitoring in pediatric anesthesia. RegistrationNCT05233449.

Nosisepsiyonun Monitörizasyonu

Tissue damage and inflammation-induced nociception during surgery are the primary reasons for administering general anesthesia to the patient. During general anesthesia, analgesics inhibit autonomic and somatic responses, hypnotic agents prevent awareness, and neuromuscular blocking agents inhibit reflex movements. Careful monitoring of the effects of general anesthesia is necessary to avoid over- or under-dosing of anesthetics and thus to prevent associated complications and adverse effects. In general, hemodynamic parameters have been used to guide the intraoperative administration of analgesics such as opioids, but hemodynamic parameters are not standardized and cannot always provide a clear assessment. There is growing interest in techniques that can objectively monitor the analgesic component of anesthesia to achieve an appropriate balance of nociception and anti-nociception and to guide analgesic administration. The purpose of this review is to provide information about nociception monitoring techniques, which are increasingly used in clinical practice. Keywords: General anesthesia, nociception, anti-nociception, monitoring

Personalised Pain Treatment in Intensive Care Units - Monitoring of Nociception

Personalised Pain Treatment in Intensive Care Units - Monitoring of Nociception

Opioid-free anesthesia with nociception monitoring in bariatric surgery: Is it effective enough?

Opioid-free anesthesia with nociception monitoring in bariatric surgery: Is it effective enough?

Lower dose of sufentanil was associated with higher plasmatic level of cortisol in patients undergoing elective cardiac surgery at the same depth of anaesthesia: a prospective randomised pilot study. Do we overlook ''stress under the surface''?

Objective monitoring of per-operative nociception remains an unanswered challenge. Anaesthetists still mostly rely on signs of activation of the sympathetic nervous system, e.g., an increase in heart rate and blood pressure. These signs can be often blurred in cardiac surgery because of medication influencing heart rate and blood pressure or by severe hemodynamic disturbances. Such conditions create the potential for incompletely checked nociception which can lead to unrecognised “under the surface” stress reaction. We decided to investigate whether patients undergoing cardiac surgery maintained at the same level of monitored depth of anaesthesia would express differences in plasmatic level of stress hormone cortisol when given a different dose of opioid sufentanil. Nineteen patients undergoing elective cardiac surgery were included in our prospective randomised trial. All patients were anaesthetised by a standardised protocol (using midazolam, propofol, sevoflurane, sufentanil and rocuronium) and were maintained within the same range of anaesthetic depth monitored by monitor Conox (qCON 30–50). Patients were randomised in two groups. Group LS (lower sufentanil), n = 9, recieved TCI (target controlled infusion) sufentanil in dose of 0.25 ng/mL, group HS (higher sufentanil), n = 10, in dose of 0.75 ng/mL. 15 minutes after sternotomy we took blood samples for analysis of plasmatic levels of cortisol. Group LS had significantly higher plasmatic cortisol levels, median 700 nm/L, than HS, median 328 nm/L (p = 0.006). We conclude that a lower dose of sufentanil was associated with higher plasmatic level of cortisol and thus more significant activation of hypothalamic–pituitary–adrenal axis stress response. We emphasise that activation of stress response can be underestimated during cardiac surgery. Our result supports the need for developing an objective monitoring method of per-operative nociception.

Can nociception monitors be used to titrate remifentanil with a stable low noxious stimulation response index (NSRI)?

Purpose: Opioids blunt autonomic nervous system (ANS) responses to noxious stimuli. Nociception monitors analyze the same ANS responses and thus might prove useful to guide opioid dosing. However, concomitantly administered hypnotics also blunt ANS responses and may thus jeopardize the usefulness of nociception monitors to guide intra-operative opioid dosing. We therefore studied the PK (prediction probability) of 3 nociception monitors (NOL index, qNOX and SPI) for the prevailing opioid concentration while maintaining the NSRI (noxious stimulus response index) at a low constant value with a range of opioids and inhaled agent combinations. Methods: In 24 consenting ASA I-II patients undergoing robotic assisted radical prostatectomy, anesthesia was maintained with desflurane in O2/air and remifentanil (target controlled infusion). During the dissection phase, the remifentanil effect site concentration (Ce) in each patient was maintained at 1, 3, or 5 ng/mL for 20 min while the end-expired desflurane concentration (FET) was adjusted to keep the noxious stimulus response index (NSRI) at 5; the sequence in which each patient received each of the three remifentanil Ce was randomized. After stabilization, during each 20 min study period, the following data were collected: NSRI, NOL Index, SPI, qNOX, and FETdes. For each parameter, the prediction probability (PK) for Ce remifentanil was calculated. Results: All patients remained hemodynamically stable. Surgery was finished before the last data collection period in 5 patients with a remifentanil Ce = 5 ng/mL, and in 1 patient with a remifentanil Ce = 1 ng/mL. All other data have been included in the data analysis. The prediction probability (PK) calculated for NOL Index, qNOX and SPI for Ce remifentanil was 0.519, 0.470, and 0.477, respectively. Conclusion: Nociception monitoring becomes useless to titrate opioids when the concomitantly administered hypnotic is adjusted to maintain a low NSRI, presumably because suppression of movement to laryngoscopy also ensures suppression of the sympathetic nervous system response to the noxious stimulus present during intra-abdominal resection of the prostate. Both the hypnotic/opioid ratio and stimulus intensity of the stimulus/response pair need to be considered when attempting to use nociception to guide opioid administration.

Electroencephalogram-based prediction and detection of responsiveness to noxious stimulation in critical care patients: a retrospective single-centre analysis

BackgroundMonitoring of pain and nociception in critical care patients unable to self-report pain remains a challenge, as clinical signs are neither sensitive nor specific. Available technical approaches are limited by various constraints. We investigated the electroencephalogram (EEG) for correlates that precede or coincide with behavioural nociceptive responses to noxious stimulation. MethodsIn this retrospective study, we analysed frontal EEG recordings of 64 critical care patients who were tracheally intubated and ventilated before, during, and after tracheal suctioning. We investigated EEG power bands for correlates preceding or coinciding with behavioural responses (Behavioural Pain Scale ≥7). We applied the Mann–Whitney U-test to calculate corresponding P-values. ResultsStrong behavioural responses were preceded by higher normalised power in the 2.5–5 Hz band (+17.1%; P<0.001) and lower normalised power in the 0.1–1.5 Hz band (–10.5%; P=0.029). After the intervention, strong behavioural responses were associated with higher normalised EEG power in the 2.5–5 Hz band (+16.6%; P=0.021) and lower normalised power in the 8–12 Hz band (–51.2%; P=0.037) ConclusionsWe observed correlates in EEG band power that precede and coincide with behavioural responses to noxious stimulation. Based on previous findings, some of the power bands could be linked to processing of nociception, arousal, or sedation effects. The power bands more closely related to nociception and arousal could be used to improve monitoring of nociception and to optimise analgesic management in critical care patients. Clinical trial registrationDRKS00011206.

Novel insights on association and reactivity of Bispectral Index, frontal electromyogram, and autonomic responses in nociception-sedation monitoring of critical care patients

BackgroundAssessing nociception and sedation in mechanically ventilated patients in the ICU is challenging, with few reliable methods available for continuous monitoring. Measurable cardiovascular and neurophysiological signals, such as frontal EEG, frontal EMG, heart rate, and blood pressure, have potential in sedation and nociception monitoring. The hypothesis of this explorative study is that derived variables from the aforementioned signals predict the level of sedation, as described by the Richmond Agitation-Sedation score (RASS), and respond to painful stimuli during critical care.MethodsThirty adult postoperative ICU patients on mechanical ventilation and receiving intravenous sedation, excluding patients with primary neurological disorders, head injury, or need for continuous neuromuscular blockage. Bispectral Index (BIS), EMG power (EMG), EMG-derived Responsiveness Index (RI), and averaged blood pressure variability (ARV) were tested against RASS measurements. The aforementioned variables together with blood pressure and Surgical Pleth Index (SPI) were explored before and after painful stimuli (for example bronchoscopy, or pleural puncture) at varying RASS levels, to test variable responsiveness.ResultsBIS, EMG, and RI predicted RASS levels with a prediction probability (PK) of 0.776 for BIS, 0.761 for EMG, and 0.763 for RI. In addition, BIS, EMG, and ARV demonstrated responsiveness to painful stimuli during deep sedation (RASS score ≤ -3).ConclusionVariables derived from EEG and EMG are associated with sedation levels, as described by the RASS score. Furthermore, these variables, along with ARV, react with consistency to painful stimuli during deep sedation (RASS -5 to -3), offering novel tools for nociception-sedation monitoring of mechanically ventilated ICU patients requiring deep sedation.

Intraoperative Assessment of Surgical Stress Response Using Nociception Monitor under General Anesthesia and Postoperative Complications: A Narrative Review.

We present a narrative review focusing on the new role of nociception monitor in intraoperative anesthetic management. Higher invasiveness of surgery elicits a higher degree of surgical stress responses including neuroendocrine-metabolic and inflammatory-immune responses, which are associated with the occurrence of major postoperative complications. Conversely, anesthetic management mitigates these responses. Furthermore, improper attenuation of nociceptive input and related autonomic effects may induce increased stress response that may adversely influence outcome even in minimally invasive surgeries. The original role of nociception monitor, which is to assess a balance between nociception caused by surgical trauma and anti-nociception due to anesthesia, may allow an assessment of surgical stress response. The goal of this review is to inform healthcare professionals providing anesthetic management that nociception monitors may provide intraoperative data associated with surgical stress responses, and to inspire new research into the effects of nociception monitor-guided anesthesia on postoperative complications.

Analgesia as a Component of General Anesthesia: A Problem of Terminology?

The state of general anesthesia is often presented with its analgesic component included. An example of this can be found in one of the classic definitions of the anesthetic state by Dr. Edmond Eger.1 He describes analgesia as an “unmeasurable component (the anesthetized patients cannot tell an investigator that he/she hurts or does not hurt)”; in addition, he states that “surrogate measures (increases in breathing, blood pressure and heart rate with surgery) suggest that some pain is perceived.” This description reflects two problems that have became obvious with new developments in our understanding of pain and nociception.The first is related to the analgesic properties of general anesthetics. Does the blockade of a nocifensive response produced by an anesthetic increment in an unconscious patient represent analgesic action? If the answer is yes, it contradicts the 2020 definition of pain accepted by the International Association for the Study of Pain, which states: “An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.” A note associated with this definition indicates that “Pain and nociception are different phenomena. Pain cannot be inferred solely from activity in sensory neurons.”2 Pain is described as both a sensory and an emotional experience. To fit the definition of pain, the term “analgesic action,” in conjunction with general anesthetics, should be applied only when consciousness is present. An anesthetized, unarousable subject responding to noxious stimuli with movement or an increase in heart rate does not have “unpleasant sensory and emotional experience.” It is impossible to determine precisely when—during the induction of anesthesia—nocifensive responses are already not indicative of pain. In an anesthetized patient, the presence of pain, at least as it is required by the International Association of the Study of Pain definition, is not certain. Therefore, the suppression of a nociceptive response by general anesthetics beyond the state of any degree of unconsciousness probably should be regarded as an antinociceptive effect, not an analgesic one.The second problem is associated with the previously mentioned indication that some pain may be perceived during the state of general anesthesia. What is the appropriate term for this phenomenon? I believe that such terminology is already in use—for the quantification of nociception in unconscious subjects during anesthesia, such as “nociception monitoring.”3,4 Nociception is not a subjective feeling, but the physiologic encoding and processing of nociceptive stimuli through the sensory system. It is the reaction to nociception that is being used for the purpose of nociception monitoring.3 The most frequently utilized response is an increase in sympathetic activity (increased heart rate, peripheral vasoconstriction, pupillary dilatation, an increase in galvanic skin conduction, among others). Various nociception monitors are already available, and others are being developed. They estimate nociception during anesthesia and can be used to optimize the administration of antinociceptive agents. Although some nociception monitors show promising results, no clear conclusions on anesthesia-related outcome can be drawn. Various categories of drugs are used as antinociceptive agents in general anesthesia.5 Differential antinociceptive effects of drugs used for anesthesia were most clearly illustrated by Prys-Roberts.6 He showed that the depth of anesthesia can be defined by suppression of the clinically relevant responses to noxious stimuli. He divided autonomic responses into four categories—breathing, hemodynamic, sudomotor, and hormonal—and showed that they can be altered differentially by drug and dose. A strategy for choosing a combination of agents that act at different targets in the nociceptive system to control nociception in anesthetized patients was recently presented by Brown et al.5When discussing general anesthetics, the term “analgesic effect” should be used only when consciousness is present; if not, “antinociceptive effect” is the better term to apply.Support was provided solely from institutional and/or departmental sources.The author declares no competing interests.

Reduced postoperative pain in patients receiving nociception monitor guided analgesia during elective major abdominal surgery: a randomized, controlled trial

The Nociception Level index (NOL™) is a multiparameter index, based on artificial intelligence for the monitoring of nociception during anesthesia. We studied the influence of NOL-guided analgesia on postoperative pain scores in patients undergoing major abdominal surgery during sevoflurane/fentanyl anesthesia. This study was designed as a single-center, prospective randomized, controlled study. After Institutional Review Board approval and written informed consent, 75 ASA 1–3 adult patients undergoing major abdominal surgery, were randomized to NOL-guided fentanyl dosing (NOL) or standard care (SOC) and completed the study. The sevoflurane target MAC range was 0.8–1.2. In the NOL-guided group (N = 36), when NOL values were > 25 for at least 1 min, a weight adjusted fentanyl bolus was administered. In the control group (N = 39) fentanyl administration was based on hemodynamic indices and clinician judgement. After surgery, pain, was evaluated using the Numerical Rating Scale (NRS) pain scale, ranging from 0 to 10, at 15 min intervals for 180 min or until patient discharge from the PACU. Median postoperative pain scores reported were 3.0 [interquartile range 0.0–5.0] and 5.0 [3.0–6.0] at 90 min in NOL-guided and control groups respectively (Bootstrap corrected actual difference 1.5, 95% confidence interval 0.4–2.6). There was no difference in postoperative morphine consumption or intraoperative fentanyl consumption. Postoperative pain scores were significantly improved in nociception level index-guided patients. We attribute this to more objective fentanyl dosing when timed to actual nociceptive stimuli during anesthesia, contributing to lower levels of sympathetic activation and surgical stress. Clinicaltrials.gov identifier: NCT03970291 date of registration May 31, 2019.

Quantitative assessment of a pediatric nociception monitor in children under sevoflurane anesthesia

IntroductionIntraoperative monitoring of nociception has recently made substantial progress in adult anesthesia. In contrast, pediatric data are scarce. Newborn-Infant Parasympathetic Evaluation (NIPE index, Mdoloris Medical Systems, Loos, France) is the...