Nociception Index Research Articles

Когнитивный дефицит как следствие общего обезболивания в офтальмохирургии у послеоперационных пациентов

В этом исследовании рассматривалось влияние выбранного метода анестезии на когнитивные функции в послеоперационном периоде. Анализ когнитивного статуса проведен при помощи нейропсихологического тестирования: шкала лобных дисфункций (Frontal Assessment Battery, FAB), краткая шкала оценки психического статуса (Mini-Mental State Examination, MMSE). Оценивание проводилось в три этапа: накануне оперативного вмешательства, через 6 часов после него и на 21-й день послеоперационного периода. Пациенты были распределены на две группы: больные группы d получали общую анестезию с применением дексмедетомидина за 40 минут до операции, поддержание анестезии — севофлурано-кислородная смесь на малом потоке газа; в группе b общая анестезия была дополнена блокадой крылонебной ямки за 20 минут до вмешательства. Группы были статистически сопоставимы по возрасту и полу. Оценка глубины анальгезии контролировалась при помощи показателя индекса анальгезии при ноцицептивном воздействии (Аnalgesia Nociception Index, ANI), оценка глубины анестезии — по биспектральному индексу (Bispectral index, BIS). Результаты проведенного исследования показали, что согласно данным нейропсихологического тестирования по шкалам MMSE и FAB показатели были более низкими в послеоперационном периоде в группе с использованием общего обезболивания в комбинации с блокадой крылонебной ямки, чем в группе с использованием дексмедетомидина как компонента мультимодального обезболивания (p < 0,001). При оценке результата через 6 часов после оперативного вмешательства в группе b по шкале MMSE показатели снизились на 20,8 %, по шкале FAB — на 28,6 % от начального уровня. При проведении анализа результатов в группе d через 6 часов после оперативного вмешательства показатели когнитивного состояния по шкале MMSE были ниже исходного уровня на 8,3 %, по шкале FAB — на 13,3 %. Нейропсихологическое тестирование на 21-е сутки по шкалам MMSE и FAB зафиксировало восстановление состояния когнитивных функций в обеих группах. Вывод. Когнитивное состояние у офтальмохирургических пациентов после сквозной кератопластики согласно шкалам MMSE и FAB при обоих видах обезболивания существенно отличалось на втором этапе исследования (через 6 часов), а со временем (через 21 день) различия между группами с использованием блокады крылонебной ямки и применением дексмедетомидина стали незначительными (p > 0,05).

The experience of using dexmedetomidine as an adjuvant of anesthesia in ophthalmic surgery

Various techniques are applied to reduce the severity of postoperative pain and discomfort in patients. The purpose of this research work was to evaluate the effectiveness and safety of Dexmedetomidine as an adjuvant of anesthesia in ophthalmic surgery. The study included 80 patients who underwent corneal transplantation on the basis of Dnepropetrovsk Regional Clinical Ophthalmologic Hospital. Patients were divided into 2 groups: control (group K) – 30 men and main (group D) – 50 ones. Multicomponent balanced anesthesia was applied in both groups. Sibazone was administered as the sedative medicine in the group K, Dexmedetomedin was administered in the group D. The main criteria for evaluating the research results were hallmarked: hemodynamic stability during surgery, the amount of administered opiates, the severity of intraoperative pain syndrome by evaluating the ANI index (ANI – analgesia nociception index), the severity of postoperative pain syndrome and the frequency of postoperative nausea and vomiting (PONV). Both schemes of anesthesia allowed avoiding pronounced fluctuations in hemodynamic parameters and gas exchange at all stages of the study. Analyzing the severity of intraoperative pain, we found that in group K pain relief could be considered insufficient during the first 7 minutes of the most traumatic stage of the surgery, while in group D the ANI index did not fall below 50. Statistically significant differences were obtained on minute 1, 2, 5, 6, and 7 of the surgery. The number of episodes of insufficient anesthesia during the most traumatic stage of the surgery in group K was statistically significantly higher than in group D. Analyzing the quality of pain relief in the postoperative period it was determined, that the level of pain on the Visual Analog Scale (VAS) after awakening in both groups was equal to 0. At the next three stages of the study (2 hours, 6 hours after surgery, and the next morning), the level of pain in group K was significantly higher than in group D. In addition, it was determined that the need for narcotic analgesics and the number of episodes of postoperative nausea and vomiting in group K was statistically significantly higher than in group D. These given data allow us to conclude that Dexmedetomedin is the effective adjuvant of the anesthesia for corneal transplantation.

Is the heart rate variability monitoring using the analgesia nociception index a predictor of illness severity and mortality in critically ill patients with COVID-19? A pilot study.

IntroductionThe analysis of heart rate variability (HRV) has proven to be an important tool for the management of autonomous nerve system in both surgical and critically ill patients. We conducted this study to show the different spectral frequency and time domain parameters of HRV as a prospective predictor for critically ill patients, and in particular for COVID-19 patients who are on mechanical ventilation. The hypothesis is that most severely ill COVID-19 patients have a depletion of the sympathetic nervous system and a predominance of parasympathetic activity reflecting the remaining compensatory anti-inflammatory response.Materials and methodsA single-center, prospective, observational pilot study which included COVID-19 patients admitted to the Surgical Intensive Care Unit was conducted. The normalized high-frequency component (HFnu), i.e. ANIm, and the standard deviation of RR intervals (SDNN), i.e. Energy, were recorded using the analgesia nociception index monitor (ANI). To estimate the severity and mortality we used the SOFA score and the date of discharge or date of death.ResultsA total of fourteen patients were finally included in the study. ANIm were higher in the non-survivor group (p = 0.003) and were correlated with higher IL-6 levels (p = 0.020). Energy was inversely correlated with SOFA (p = 0.039) and fewer survival days (p = 0.046). A limit value at 80 of ANIm, predicted mortalities with a sensitivity of 100% and specificity of 85.7%. In the case of Energy, a limit value of 0.41 ms predicted mortality with all predictive values of 71.4%.ConclusionA low autonomic nervous system activity, i.e. low SDNN or Energy, and a predominance of the parasympathetic system, i.e. low HFnu or ANIm, due to the sympathetic depletion in COVID-19 patients are associated with a worse prognosis, higher mortality, and higher IL-6 levels.

FEATURES OF COGNITIVE STATUS OF OPHTHALMIC PATIENTS AS A PREDICTOR OF POSTOPERATIVE COGNITIVE DYSFUNCTIONS

The influence of the chosen method of anesthesia on cognitive functions in the postoperative period is investigated in the article. Cognitive status analysis was performed using neuropsychological testing: Frontal Assessment Battery (FAB), short-term mental status assessment scale (Mini-MentalStateExamination - MMSE). The evaluation was performed in 3 stages: on the eve of surgery, 7 days after it and on the 21st day of the postoperative period. Patients were divided into two groups: group k - patients received general anesthesia with narcotic analgesics and benzodiazepines in premedication for 40 minutes, maintenance of anesthesia - sevoflurano - oxygen mixture on a low gas stream. minutes before surgery. Estimation of the depth of analgesia was monitored using ANI (Analgesia Nociception Index, index of analgesia with nociceptive effect), evaluation of the depth of sedation - by BIS (Bispectral index, Bispectral index). Patients in both groups were statistically comparable by gender and age. Given the comparative analysis of changes in neuropsychological testing on the FAB scale, the average in the group using dexmedetomidine increased by 13.3% relative to baseline. After a comparative analysis of neuropsychological testing on the MMSE scale, the indicators in the group using dexmedetomid while in the group with the "classical" method of anesthesia, they did not change significantly. Based on the data obtained, it can be argued that the use of dexmedetomidine, as a component of multimodal analgesia, has a positive effect on the state of cognitive functions in the post-anesthetic period.

Performance of the Surgical Pleth Index and Analgesia Nociception Index in Healthy Volunteers and Parturients.

Various commercially available nociception devices have been developed to quantify intraoperative pain. The Surgical Pleth Index (SPI) and Analgesia Nociception Index (ANI) are among the analgesic indices that have been widely used for the evaluation of surgical patients. This study aimed to evaluate the clinical performance of the SPI and ANI in conscious healthy volunteers and parturients. Ten healthy volunteers and 10 parturients participated in this study. An algometer was used to induce bone pain in the volunteers until they rated their pain as five on the numerical rating scale (NRS); this procedure was repeated during the administration of remifentanil or normal saline. The study comprised two periods, and the volunteers were infused with different solutions in each period: normal saline during one period and remifentanil during the other in a randomized order. The parturients’ SPI and ANI data were collected for 2 min when they rated their pain levels as 0, 5, and 7 on the NRS, respectively. Both the SPI and ANI values differed significantly between NRS 0 and NRS 5 (P < 0.001) in the volunteers, irrespective of the solution administered (remifentanil or normal saline). At NRS 5, the SPI showed similar values, irrespective of remifentanil administration, while the ANI showed significantly lower values on remifentanil administration (P = 0.028). The SPI and ANI values at NRS 5 and NRS 7 did not differ significantly in the parturients (P = 0.101 for SPI, P = 0.687 for ANI). Thus, the SPI and ANI were effective indices for detecting pain in healthy volunteers and parturients.

Comparative study of analgesia nociception index (ANI) vs. standard pharmacokinetic pattern for guiding intraoperative fentanyl administration among mastectomy patients

BackgroundThe Analgesia Nociception Index (ANI) has been suggested as a non-invasive guide for analgesia. Our objective was to compare the efficacy of ANI vs. standard pharmacokinetic pattern for guiding intraoperative fentanyl administration.MethodsThis was a prospective, randomized, controlled study of adult female patients undergoing elective mastectomy under general anesthesia. The patients were randomized to the ANI-guided group receiving a loading dose of 75 μg of fentanyl followed by 25 μg when the ANI score was under 50. The Control group received the same loading dose followed by 25 μg every 30 min with additional doses when there were signs of inadequate analgesia (viz., tachycardia or hypertension).ResultsSixty patients—30 in each group—were recruited. Although the actual mean ANI score was higher in the ANI-guided than in the Control group (mean difference 2.2; 95% CI: 0.3 to 4.0, P = 0.022), there was no difference in the primary outcome—i.e., intraoperative fentanyl consumption (mean difference − 4.2 μg; 95% CI: − 24.7 to 16.4, P = 0.686 and − 0.14 μg·kg− 1·h− 1; 95% CI: − 0.31 to 0.03, P = 0.105). No difference between groups was shown for either intraoperative blood pressure and heart rate, or for postoperative outcomes (i.e., pain scores, morphine consumption, or sedation scores) in the postanesthesia care unit.ConclusionsIntraoperative fentanyl administration guided by ANI was equivalent to that guided by a modified pharmacologic pattern. In a surgical model of mastectomy, the ANI-guided intraoperative administration of fentanyl had no impact on clinical outcomes.Trial registrationThe study was registered with ClinicalTrials.gov (NCT03716453) on 21/10/2018.

Assessing the antinociceptive effect of nitrous oxide to tetanic stimulation in anaesthetised patients with new intra-operative nociception monitors: An observational study.

Nitrous oxide (N2O) has been used since the 19th century for its analgesic, antinociceptive and anxiolytic effects during surgical procedures in awake and anaesthetised patients. However, quantification of noxious stimuli that occur under general anaesthesia is a constant challenge for anaesthesiologists, and recently two new indices have been developed to assess intra-operative nociception. The aim of this study was to quantify with new indices as well as with more classical clinical parameters the antinociceptive effect of N2O during general anaesthesia. Prospective, open label, patient-blinded, observational and descriptive trial. Single-centre academic hospital. Forty American Society of Anesthesiologists' physical status 1 to 3 patients undergoing general anaesthesia for elective abdominal surgery via laparotomy were recruited. Intra-operative pain was assessed using a standardised electrical stimulation of the forearm (tetanic stimulation at 70 mA, 100 Hz for 30 s), at 0, 25 and 50% inhaled N2O/O2. Heart rate (HR), mean arterial blood pressure, bispectral index, the analgesia nociception index and the nociception level (NOL) index were used to evaluate intra-operative nociception before and after each standardised tetanic stimulation. There was a 16% reduction of the analgesia nociception index reaction, a 31% reduction of the NOL reaction and a 51% reduction of the HR reaction to a standardised electrical tetanic nociceptive stimulation during administration of 50% N2O. Administration of 50 or 25% inhaled N2O produced the same quality of antinociception based on HR and NOL index analyses. HR and the NOL index were the best parameters to identify the antinociceptive effect of intra-operatively administered N2O. In anaesthetised patients, our study demonstrated clinically significant antinociceptive properties of N2O. Our results showed that low concentrations of N2O (25%) are as effective as higher concentrations (50%) to achieve a significant antinociceptive effect. These findings may help decrease negative effects of using higher concentrations of N2O, including its side effects and its environmental pollution. ClinicalTrials.gov registration identifier: NCT02701478.

Trance-it to the Future

Trance-it to the Future

Application of bispectral index and analgesia nociception index monitoring during laparoscopic cholecystectomy

The study provides a theoretical generalization and substantive solution to the scientific and practical problem of increasing the efficiency of anesthesia for surgical interventions, such as laparoscopic cholecystectomy, under individualized anesthetic support. This study also presents the peculiar courses of various anesthetic methods during the perioperative period in 120 patients with cholelithiasis who underwent laparoscopic cholecystectomy. Anesthesia types included total intravenous anesthesia using propofol and inhalation anesthesia with sevoflurane. Monitoring the bispectral index and analgesia and nociception index has been widely performed to assess the adequacy of various anesthetic options. These indices were also monitored to assess hemodynamic and autonomic regulation parameters in real time and to predict changes in these parameters intraoperatively. The results suggested the broad possibilities of monitoring, controlling, and minimizing the effect anesthesia on the cardiovascular system in conditions associated with a transient increase in the intra-abdominal pressure.

Machine learning techniques for computer-based decision systems in the operating theatre: application to analgesia delivery

Abstract This work focuses on the application of machine learning techniques to assist the clinicians in the administration of analgesic drug during general anaesthesia. Specifically, the main objective is to propose the basis of an intelligent system capable of making decisions to guide the opioid dose changes based on a new nociception monitor, the analgesia nociception index (ANI). Clinical data were obtained from 15 patients undergoing cholecystectomy surgery. By means of an off-line study, machine learning techniques were applied to analyse the possible relationship between the analgesic dose changes performed by the physician due to the hemodynamic activity of the patients and the evolution of the ANI. After training different classifiers and testing the results under cross validation, a preliminary relationship between the evolution of ANI and the dosage of remifentanil was found. These results evidence the potential of the ANI as a promising index to guide the infusion of analgesia.

Hybrid Intelligent Model to Predict the Remifentanil Infusion Rate in Patients Under General Anesthesia

Abstract Automatic control of physiological variables is one of the most active areas in biomedical engineering. This paper is centered in the prediction of the analgesic variables evolution in patients undergoing surgery. The proposal is based on the use of hybrid intelligent modelling methods. The study considers the Analgesia Nociception Index (ANI) to assess the pain in the patient and remifentanil as intravenous analgesic. The model proposed is able to make a one-step-ahead prediction of the remifentanil dose corresponding to the current state of the patient. The input information is the previous remifentanil dose, the ANI variable and the electromyogram signal. Modelling techniques used are Artificial Neural Networks and Support Vector machines for Regression combined with clustering methods. Both training and validation were done with a real dataset from different patients. Results obtained show the potential of this methodology to calculate the drug dose corresponding to a given analgesic state of the patient.

Effect of combinations of morphine, dexmedetomidine and maropitant on the electroencephalogram in response to acute electrical stimulation in anaesthetized dogs.

This study was conducted to compare the efficacy of combinations of morphine, dexmedetomidine and maropitant in preventing the changes in electroencephalographic (EEG) indices of nociception in anaesthetized dogs subjected to a noxious electrical stimulus. In a crossover study, eight healthy adult dogs were randomly allocated to four groups: Mor: morphine 0.6mg/kg; Dex+Mor: morphine 0.3mg/kg+dexmedetomidine 5μg/kg; Maro+Mor: morphine 0.3mg/kg+maropitant 1mg/kg; and Dex+Maro+Mor: morphine 0.2mg/kg+dexmedetomidine 3μg/kg+maropitant 0.7mg/kg. Following intramuscular administration of test drugs in a minimal anaesthesia model, a supramaximal electrical stimulus (50V at 50Hz for 2s) was applied and the EEG data were recorded. There were significant increases (p<.05) in the poststimulus median frequency (F50) only in groups Mor and Maro+Mor. Dex+Mor group had a significantly lower change in F50 and F95 compared to all other treatment groups. There was no correlation of the changes in EEG frequencies with blood plasma concentration of the drugs during and after noxious stimulation. Combination of dexmedetomidine and morphine was most effective in abolishing the changes in EEG indices in response to a noxious stimulus indicating a supra-additive interaction between these two drugs.

Performance of the nasal photoplethysmographic index as an analgesic index during surgery under general anaesthesia

In a previous study, we developed a new analgesic index using nasal photoplethysmography (nasal photoplethysmographic index, NPI) and showed that the NPI was superior to the surgical pleth index (SPI) in distinguishing pain above numerical rating scale 3. Because the NPI was developed using data obtained from conscious patients with pain, we evaluated the performance of NPI in comparison with the SPI and the analgesia nociception index (ANI) in patients under general anaesthesia with target-controlled infusion of propofol and remifentanil. The time of nociception occurrence was defined as when the signs of inadequate anaesthesia occurred. The median values of NPI, SPI, and ANI for 1 minute from the time of the sign of inadequate anaesthesia were determined as the value of each analgesic index that represents inadequate anaesthesia. The time of no nociception was determined as 2 minutes before the onset of skin incision, and the median value for 1 minute from that time was defined as the baseline value. In total, 81 patients were included in the analysis. NPI showed good performance in distinguishing inadequate anaesthesia during propofol-remifentanil based general anaesthesia. NPI had the highest value in terms of area under the receiver operating characteristic curve, albeit without statistical significance (NPI: 0.733, SPI: 0.722, ANI: 0.668). The coefficient of variations of baseline values of NPI, SPI, and ANI were 27.5, 47.2, and 26.1, respectively. Thus, the NPI was effective for detecting inadequate anaesthesia, showing similar performance with both indices and less baseline inter-individual variability than the SPI.

The Association Between Pain Relief Using Video Games and an Increase in Vagal Tone in Children With Cancer: Analytic Observational Study With a Quasi-Experimental Pre/Posttest Methodology.

BackgroundPatients with secondary pain due to mucositis after chemotherapy require treatment with morphine. Use of electronic video games (EVGs) has been shown to be an effective method of analgesia in other clinical settings.ObjectiveThe main objective of this study was to assess the association between the use of EVGs and the intensity of pain caused by chemotherapy-induced mucositis in pediatric patients with cancer. The secondary objective was to assess the association between changes in pain intensity and sympathetic-parasympathetic balance in this sample of pediatric patients.MethodsClinical records were compared between the day prior to the use of EVGs and the day after the use of EVGs. The variables were variations in pupil size measured using the AlgiScan video pupilometer (IDMed, Marseille, France), heart rate variability measured using the Analgesia Nociception Index (ANI) monitor (Mdoloris Medical Systems, Loos, France), intensity of pain measured using the Numerical Rating Scale (score 0-10), and self-administered morphine pump parameters.ResultsTwenty patients (11 girls and nine boys; mean age 11.5 years, SD 4.5 years; mean weight 41.5 kg, SD 20.7 kg) who met all the inclusion criteria were recruited. EVGs were played for a mean of 2.3 (SD 1.3) hours per day, resulting in statistically significant changes. After playing EVGs, there was significantly lower daily morphine use (before vs after playing EVGs: 35.9 vs 28.6 µg/kg/day, P=.003), lower demand for additional pain relief medication (17 vs 9.6 boluses in 24 hours, P=.001), lower scores of incidental pain intensity (7.7 vs 5.4, P=.001), lower scores of resting pain (4.8 vs 3.2, P=.01), and higher basal parasympathetic tone as measured using the ANI monitor (61.8 vs 71.9, P=.009). No variation in pupil size was observed with the use of EVGs.ConclusionsThe use of EVGs in pediatric patients with chemotherapy-induced mucositis has a considerable analgesic effect, which is associated physiologically with an increase in parasympathetic vagal tone despite lower consumption of morphine.

Analgesia nociception index as a tool to predict hypotension after spinal anaesthesia for elective caesarean section

Arterial hypotension is the main disadvantage of spinal anaesthesia (SA) for caesarean delivery with deleterious effects on maternal–foetal outcomes. Recently, a non-invasive device ‘analgesia nociception index’ (ANI) has been developed to evaluate the parasympathetic component of the nervous autonomous system. The aim of this study was to evaluate the ability of ANI to predict the risk of hypotension after SA for elective caesarean section. One hundred patients scheduled for elective caesarean delivery under SA were recruited in this observational prospective study. Hemodynamic and ANI parameters were recorded in supine position (TB), in sitting position (T0), after induction of SA (T1) and then every three minutes (T2, T3, Tn) until the end of surgery or having resort to ephedrine. After SA, women were classified into two groups according to occurrence of hypotension (group H, n = 80) or not (group C, n = 20). The variations of ANI between T2 and T0 were significantly higher in the group H as compared to the control group. A threshold of 4.5 points decrease in instantaneous ANI value could predict maternal hypotension. ANI is a simple and effective tool in predicting the risk of SA-related hypotension. Impact statement What is already known on this subject? Arterial hypotension is the main disadvantage of spinal anaesthesia for caesarean delivery with deleterious effects on maternal-foetal outcomes. The balance between the sympathic and parasympathic systems could be used to predict the onset of hypotension following spinal anaesthesia. Analgesia nociception index (ANI) is an index calculated based on heart rate variability HRV analysis, designed originally to evaluate the antinociception/Nociception balance. What do the results of this study add? We have shown that the analysis of HRV with ANI was a predictor of maternal hypotension after spinal anaesthesia. What are the implications of these findings for clinical practice and/or further research? ANI is an effective tool in predicting the risk of spinal anaesthesia-related hypotension. These findings are of potential clinical importance in the obstetrical anaesthesia setting. Further studies are required in order to implement this simple tool and optimise prophylactic measures especially vasopressors.

Association between intraoperative nociception and surgical invasiveness in patients undergoing non-cardiac surgery under general anesthesia: a retrospective cohort study.

There are several indexes of intraoperative nociception during surgery under general anesthesia. Although a higher degree of surgical invasiveness increases intraoperative nociception, an association between the index of intraoperative nociception and severity of surgical invasiveness has not been reported. We hypothesized that there is associations between averaged values of nociceptive response (NR) throughout surgery (mean NR), as the index of intraoperative nociception, and surgical severity codes in the Surgical outcome risk tool (SORT) or procedure risk codes in the Surgical mortality probability model (S-MPM). The primary outcome was the association between mean NR and severity scores of surgical procedure. Hence, a single institutional retrospective cohort study was performed in consecutive patients undergoing non-cardiac surgery under general anesthesia from June 2018 to May 2019. There were significant increases in the three categories of procedure risk in the S-MPM corresponding to the increase in mean NR values in 5090 patients. In the SORT, the highest intensity in the four categories of surgical severity also significantly correlated with the increase in mean NR values. Increasing intensity of intraoperative nociception is likely associated with higher severity codes of surgical invasiveness in prediction models for postoperative morbidity and mortality.

Usefulness of ANI (analgesia nociception index) monitoring for outpatient saphenectomy surgery outcomes: an observational study

The Analgesia Nociception Index (ANI), derived from heart rate variability is a proposed guide to obtain an adequate control of the analgesic component during anaesthesia. This single blind observational study was designed to evaluate the relationship between intraoperative ANI values and length of stay in Day Surgery Units (DSU) in patients undergoing varicose vein intervention. 131 patients (ASA I-II) scheduled for elective varicose vein surgery were studied. A propofol closed-loop TCI was used to maintain a specific level of BIS. To control analgesia, a remifentanil TCI was used, modifying the target according to hemodynamic changes. Patients were included in the ANI > 50 sub-group or in the ANI < 50 sub-group depending on whether the ANI value was greater than 50 for at least 60% of the anaesthesia maintenance period (AMP) or not. The primary endpoint was the length of stay in DSU. Other variables studied were ANI values, duration of the AMP, remifentanil TCI target average, postoperative pain, rescue-analgesia needs and postoperative nausea and vomiting (PONV) were analysed. Statistical analysis of length of stay in DSU was performed with Mann-Whitney test. ANI > 50 sub-group showed a lower length of stay in the DSU [165min (118-212) vs 186.5min (119-254), p = 0.0425]. Discharge timing from DSU was statistically different among study sub-groups (p = 0.005). An adequate nociception level measured by ANI during varicose vein surgery might reduce the length of stay at DSU. Further studies are needed to assess the usefulness of ANI in other anaesthesia conditions.

Machine learning based method for the evaluation of the Analgesia Nociception Index in the assessment of general anesthesia

Measuring the level of analgesia to adapt the opioids infusion during anesthesia to the real needs of the patient is still a challenge. This is a consequence of the absence of a specific measure capable of quantifying the nociception level of the patients. Unlike existing proposals, this paper aims to evaluate the suitability of the Analgesia Nociception Index (ANI) as a guidance variable to replicate the decisions made by the experts when a modification of the opioid infusion rate is required. To this end, different machine learning classifiers were trained with several sets of clinical features. Data for training were captured from 17 patients undergoing cholecystectomy surgery. Satisfactory results were obtained when including information about minimum values of ANI for predicting a change of dose. Specifically, a higher efficiency of the Support Vector Machine (SVM) classifier was observed compared with the situation in which the ANI index was not included: accuracy: 86.21% (83.62%–87.93%), precision: 86.11% (83.78%–88.57%), recall: 91.18% (88.24%–91.18%), specificity: 79.17% (75%–83.33%), AUC: 0.89 (0.87–0.90) and kappa index: 0.71 (0.66–0.75). The results of this research evidenced that including information about the minimum values of ANI together with the hemodynamic information outperformed the decisions made regarding only non-specific traditional signs such as heart rate and blood pressure. In addition, the analysis of the results showed that including the ANI monitor in the decision making process may anticipate a dose change to prevent hemodynamic events. Finally, the SVM was able to perform accurate predictions when making different decisions commonly observed in the clinical practice.

Effectiveness of the Analgesia Nociception Index Monitoring in Patients Who Undergo Colonoscopy with Sedo-Analgesia.

ObjectiveThe objective of this study was to improve the patient comfort and safety during procedures done under anaesthesia and sedation. The analgesia nociception index (ANI) noninvasively provides information on the nociception-antinociception balance, and it can be used to assess analgesia objectively. We aimed to compare the effects of analgesia management with conventional methods and with ANI monitoring on total opioid consumption, sedation and analgesia levels in patients who underwent colonoscopy using sedo-analgesia.MethodsAdult patients (n=102), scheduled for procedural sedation, were prospectively analysed. After the induction with propofol and ketamine, infusions of propofol (2 mg kg−1 h−1) and remifentanil (0.05 mcg kg−1 min−1) were started. In Group A, remifentanil infusions were titrated to maintain the ANI value between 50 and 70, whereas in Group C, analgesic requirements were met according to the attending anaesthetist’s intention. The heart rate, blood pressure, respiratory rate, SpO2, BIS, Numeric Rating Scale (NRS) and Ramsay Sedation Scale were monitored. Complications, analgesics consumption, duration of the procedure, demographic information, NRS and the Modified Aldrete Score were evaluated.ResultsA total remifentanil amount used in Group A was 66.51±47.87 mcg and 90.15±58.17 mcg in Group C (p=0.011); there was no difference in total amounts of ketamine and propofol given. There was a negative correlation between ANI and NRS scores of Group A patients at Minute 0 at the level of 0.402, which was significant statistically (p=0.003).ConclusionOpioid consumption was diminished when ANI monitoring was used, and thus the patient safety was improved. Further studies with longer procedure times and with a greater number of patients are required to demonstrate whether there is a difference in side effects and recovery times.

Ability of Changes in Analgesia Nociception Index to Assess the Stroke Volume Effects of a Volume Expansion of 250ml of Crystalloid in the Operating Room

Ability of Changes in Analgesia Nociception Index to Assess the Stroke Volume Effects of a Volume Expansion of 250ml of Crystalloid in the Operating Room