Preventing Postoperative Catheter-Related Bladder Discomfort (CRBD) with Bladder Irrigation Using 0.05% Lidocaine Saline Solution: Monitoring with Analgesia Nociception Index (ANI) after Transurethral Surgery.

(1) Background and Objectives: Catheter-related bladder discomfort (CRBD), a common and distressing consequence of indwelling urinary catheters, can significantly impact postoperative recovery. This study aimed to determine the effectiveness of bladder irrigation with a 0.05% lidocaine normal saline solution for the prevention of CRBD following transurethral surgery. (2) Materials and Methods: In this randomized, double-blind, placebo-controlled trial, patients were assigned to either a control group receiving normal saline or a treatment group receiving 0.05% lidocaine (2% lidocaine 25 mL in 1000 mL saline) for bladder irrigation. Both groups were administered fentanyl (1 µg/kg) for analgesia at the end of the procedure. The primary endpoint was the assessment of the incidence and severity of CRBD upon awakening within the first 6 h postoperatively, using a four-grade scale based on the patients' reports of discomfort. (3) Results: Out of 79 patients completing the study, the incidence of moderate to severe CRBD was significantly lower in the lidocaine group (5.1%, 2/39) compared to the control group (25%, 10/40) at 10 min after waking from anesthesia (p = 0.014). Furthermore, the lidocaine group experienced significantly less CRBD at 1 and 2 h postoperative (2.6% and 0%, respectively) compared to the control group (20% and 10%, respectively) (p = 0.015, p = 0.043), with no significant differences at 6 h (p = 0.317). (4) Conclusions: The results suggest that bladder irrigation with 0.05% lidocaine reduces the occurrence of moderate to severe CRBD by nearly 80% in the initial 2 h postoperative period after transurethral surgery.

High frequency variability index in predicting postoperative pain in video/robotic-assisted thoracoscopic surgery under combined general anesthesia and peripheral nerve block: an observational study.

The high frequency variability index (HFVI)/analgesia nociception index (ANI) is purported to assess the balance between nociception and analgesia in patients under general anesthesia. This observational study investigated whether intraoperative HFVI/ANI correlates with postoperative pain in patients performed with nerve block under general anesthesia in video/robotic-assisted thoracoscopic surgery (VATS/RATS). We investigated whether maximum postoperative pain at rest and postoperative morphine consumption are associated with HFVI/ANI just before extubation, mean HFVI/ANI during anesthesia, the difference in HFVI/ANI between before and 5 min after the start of surgery, and the difference in HFVI/ANI between before and 5 min after the nerve block. Data obtained from 48 patients were analyzed. We found no significant association between HFVI/ANI just before extubation and postoperative Numerical Rating Scale (NRS) score. Receiver operating characteristic curve analysis revealed that moderate (NRS > 3) or severe (NRS > 7) postoperative pain could not be predicted by HFVI/ANI just before extubation. In addition, there were no associations between postoperative morphine consumption and HFVI/ANI at any time points. The present study demonstrated that it is difficult to predict the degree of postoperative pain in patients undergoing VATS/RATS under general anesthesia combined with peripheral nerve block, by using HFVI/ANI obtained at multiple time points during general anesthesia.

Comparison of analgesia nociception index, surgical pleth index and hemodynamic parameters between patients receiving fentanyl versus dexmedetomidine analgesia for supratentorial craniotomy - an open label active-controlled randomized trial.

Dexmedetomidine decreases heart rate (HR) and increases high frequency (HF) component of HR variability (HRV). Analgesia Nociception Index (ANI) measures nociception by analyzing the influence of respiration on HF component of HRV while surgical pleth index (SPI) derives this information from photoplethymographic signals of finger arterioles. Therefore, during administration of dexmedetomidine, reliability of ANI may vary. This study compared the changes in ANI, SPI and hemodynamics (HR and mean arterial pressure [MAP]) during various noxious stimuli with fentanyl and dexmedetomidine intraoperative analgesia. In this trial, patients undergoing elective supratentorial surgery under general anesthesia were randomized to receive either fentanyl or dexmedetomidine infusion for intraoperative analgesia. ANI (instantaneous and mean), SPI, HR and MAP were compared before and after noxious stimuli (intubation, skull pin insertion, skin incision and craniotomy) with respect to magnitude of maximum change in the variable and the time taken for the maximal change (defined as response time) between the groups. A total of 58 patients, 29 in each group were recruited into the study. At intubation, SPI changed significantly more in the fentanyl group compared to dexmedetomidine group (37 versus 20 units, p = 0.007). At skull pinning, ANI values (both instantaneous and mean) changed more in dexmedetomidine group (p = 0.024 and 0.009) with significantly longer response time (p = 0.039). There was no difference between the groups with respect to any of the variables at skin incision and craniotomy. ANI during use of dexmedetomidine and SPI while using fentanyl, might be the better choices as intraoperative nociception monitors.

Analgesia nociception index is an indicator of laparoscopic trocar insertion-induced transient nociceptive stimuli.

Objective: This study aimed to investigate whether analgesia nociception index (ANI) could be an indicator of perioperative pain during laparoscopic trocar insertion. Methods: A total of 280 participants of anesthesia receiving laparoscopic surgery were enrolled. Anesthesia induction and maintenance were performed using the Marsh model for target propofol and the Minto model for remifentanil. Systolic blood pressure (SBP), heart rate (HR), and ANI were recorded at skin incision, the first-, second, the last-trocar insertion, and 5 min after the last trocar insertion. Results: ANI was significantly different among the five groups in the last four time points (all P < 0.05). Pearson's correlation showed that ANI was negatively correlated with SBP (r = -0.114, P = 0.077) and HR (r = -0.247, P < 0.001). The area under the curve of ANI was positively correlated with those of SBP (r = 0.493, P < 0.001) and HR (r = -0.420, P < 0.001). Multivariate logistic regression showed that the ANI was an independent factor associated with intraoperative hemodynamic adverse events only at 5 min after the last trocar insertion. Conclusions: Under general anesthesia, the change in ANI was consistent with changes in the balance between analgesia and nociceptive stimuli. The ANI can reflect the extent of transient pain but had a poor predictive performance for hemodynamic adverse events.

Predicting the optimal concentration of remifentanil for skull pin fixation with hemodynamic and analgesia nociception index monitoring.

Inadequate antinociception during skull pin fixation may cause hemodynamic instability in intracranial surgery. The optimal concentration of remifentanil to provide adequate antinociception and stable hemodynamics during skull pin fixation under analgesia nociception index monitoring is unknown. This study is to assess the 90% effective concentration of remifentanil for skull pin fixation under hemodynamic and analgesia nociception index monitoring. Twenty-six patients were enrolled for intracranial surgery, anesthesia was induced and maintained under total intravenous anesthesia using target-controlled infusion for remifentanil and propofol under analgesia nociception index and bispectral index monitoring. Skull pin fixation was performed at different effect-site concentrations of remifentanil required for Dixon's up-and-down method with a step size of 0.5 ng/ml under bispectral index 40-60. Inadequate antinociception is defined when either ANI < 30 or > 20% in hemodynamic changes from baseline (e.g. heart rate > 100 beats/min, or blood pressure > 180/100 mmHg) and the effect-site concentration of remifentanil is considered as failure. It is considered success as ANI > 30 and < 20% hemodynamic changes from baseline simultaneously. Seven pairs of failure/success were used for probit analysis. The 90% effective concentration of remifentanil for skull pin fixation with adequate antinociception and hemodynamic stability was 4.7 ng/ml.

Pain Assessment Using the Analgesia Nociception Index (ANI) in Patients Undergoing General Anesthesia: A Systematic Review and Meta-Analysis.

The analgesia nociception index (ANI) has emerged as a potential measurement for objective pain assessment during general anesthesia. This systematic review and meta-analysis aimed to evaluate the accuracy and effectiveness of ANI in assessing intra- and post-operative pain in patients undergoing general anesthesia. We conducted a comprehensive search of Ovid-MEDLINE, Ovid-EMBASE, Cochrane Central Register of Controlled Trials, Google Scholar, public clinical trial databases (ClinicalTrials and Clinical Research Information Service), and OpenSIGLE to identify relevant studies published prior to May 2023 and included studies that evaluated the accuracy and effectiveness of ANI for intra- or post-operative pain assessment during general anesthesia. Among the 962 studies identified, 30 met the eligibility criteria and were included in the systematic review, and 17 were included in the meta-analysis. For predicting intra-operative pain, pooled sensitivity, specificity, diagnostic odds ratio (DOR), and area under curve of ANI were 0.81 (95% confidence interval [CI] = 0.79-0.83; I2 = 68.2%), 0.93 (95% CI = 0.92-0.93; I2 = 99.8%), 2.32 (95% CI = 1.33-3.30; I2 = 61.7%), and 0.77 (95% CI = 0.76-0.78; I2 = 87.4%), respectively. ANI values and changes in intra-operative hemodynamic variables showed statistically significant correlations. For predicting post-operative pain, pooled sensitivity, specificity, and DOR of ANI were 0.90 (95% CI = 0.87-0.93; I2 = 58.7%), 0.51 (95% CI = 0.49-0.52; I2 = 99.9%), and 3.38 (95% CI = 2.87-3.88; I2 = 81.2%), respectively. ANI monitoring in patients undergoing surgery under general anesthesia is a valuable measurement for predicting intra- and post-operative pain. It reduces the use of intra-operative opioids and aids in pain management throughout the perioperative period.

The validity and applications of the analgesia nociception index: a narrative review.

Pain refers to the subjective, unpleasant experience that is related to illness or injury. In contrast to pain, nociception refers to the physiological neural processing of noxious stimuli, such as intra-operative surgical stimuli. One novel device, the Analgesia Nociception Index (ANI), aims to objectively measure intra-operative nociception by analyzing the heart rate variability in patients undergoing surgery. Through this method of nociceptive monitoring, the ANI device aims to provide an objective, continuous evaluation of patient comfort levels and allow anesthesiologists to better manage surgical stress and patient analgesia, perhaps with even better efficacy than current practices used to assess nociception. Additionally, ANI may have clinical application in settings outside of the operating room, such as in the intensive care unit. In this narrative review, we compiled and summarized the findings of many studies that have investigated ANI's validity and applications in different clinical settings. Currently, the literature appears mostly supportive of ANI's ability to detect nociception in both surgical and non-surgical settings. However, the ability for ANI to provide clinical benefits, such as decreased intra-operative opioid use, post-operative opioid use, and post-operative pain compared to standard practices appear controversial. Because of the wide variety of methodology, clinical settings, patient populations, and limitations in these studies, more investigation of ANI is needed before any firm conclusions can be drawn on its clinical benefits.

Evaluation of the effectiveness of analgesia nociception index (ANI) predictability for surgical stimuli under personal analgesic sufficiency status (PASS) measured by pre-tetanus-induced ANI: a pilot study.

The Analgesia Nociception Index (ANI) is a promising monitor to evaluate the balance of nociception and anti-nociception based on heart rate variability. This prospective, interventional, monocentric pilot study aimed to verify the effectiveness of the personal analgesic sufficiency status (PASS) measured by pre-tetanus-induced ANI variation for surgical stimuli. After Ethics approval and informed consent, participants were anesthetized with sevoflurane and increased effect-site concentrations of remifentanil step by step (2, 4, 6 ng ml-1). At each concentration, a standardized tetanic stimulus was applied (5 s, 60 mA, 50 Hz) with no other noxious stimuli presented. Through all the concentrations, defined the lowest concentration when ANI ≥ 50 as the PASS after tetanic stimuli. The surgical stimulus was conducted under at least 5-min of PASS. Thirty-two participants were analyzed. ANI, systolic blood pressure (SBP), and Heart rate (HR) except the Bispectral Index (BIS) were significantly changed at 2 ng ml-1 after tetanic stimuli, only ANI and SBP were significantly altered at 4 and 6 ng ml-1. ANI could predict inadequate analgesia status (an increase in SBP or HR of more than 20% from the baseline) at 2 and 4 ng ml-1 (P = 0.044, P = 0.049, respectively), but not at 6 ng ml-1. The PASS under pre-tetanus-induced ANI identification didn't meet the analgesic needs under surgical stimuli. Further investigations are required to provide a reliable prediction of individualized analgesia by objective nociception monitors.Trial registration NCT05063461.

Ability of the Analgesia Nociception Index variations to identify a response to a volume expansion of 250 mL of crystalloids in the operating room (REVANI): a prospective observational study.

BACKGROUND: Analgesia Nociception Index (ANI) is a device based on analysis of the R-R interval and respiratory sinus arrhythmia to assess the balance between sympathetic and parasympathetic activity. The autonomic system is directly affected by load changes. Therefore, monitoring sympathetic tone and its change could theoretically allow tracking of load changes during volume expansion. The aim of the present study was to determine whether changes in ANI are able to track the increase in stroke volume caused by volume expansion (SV). METHODS: This prospective observational study included mechanically ventilated patients undergoing neurosurgery and benefiting from SV monitoring. Exclusion criteria were cardiac dysfunction, arrhythmias, beta-blockade therapy, and dysautonomia. SV was optimized by fluid administration of 250 ml of crystalloid fluid. A positive fluid increase was defined as a SV increase of 10% or more from baseline. Changes in SV and medium ANI (ANIm) were recorded before and 4 to 5 min after volume expansion. RESULTS: Sixty-nine patients had 104 fluid challenges (36 positive and 68 negative). Volume expansion resulted in a greater ANI increase in responders than in nonresponders. The change in ANIm > 5 predicted fluid responsiveness with a sensitivity of 68.4% (95% CI: 67.4% to 69.5%) and a specificity of 51.2% (95% CI: 50.1% to 52.3%). The area under the receiver operating characteristic curve was 0.546 (95% CI: 0.544 to 0.549) and appeared to be affected by remifentanil dose and baseline ANI. CONCLUSION: Changes in ANIm induced by fluid challenge is not able to predict fluid responsiveness in mechanically ventilated patients undergoing neurosurgery. TRIAL REGISTRATION: Clinical trial registration: NCT04223414.

Analgesia Nociception Index Monitoring in the Evaluation of Postoperative Pain in Children: A Prospective Observational Pilot Study.

PURPOSE: In this study, we aimed to evaluate the relationship between the analgesia nociception index (ANI) device and pain scales used in the postoperative pain assessment of pediatric patients who underwent laparoscopic appendectomy. DESIGN: The study was designed as a correlation observational pilot study. METHODS: Postoperative pain was evaluated using pediatric pain scales (face, legs, arms, cry, consolability scale; numerical rating scale; Wong-Baker scale) and ANI device in school-aged children and adolescents. RESULTS: The mean age of the children was 14.00 ± 1.63 years, and the mean BMI was 22.52. We found a statistically significant positive correlation between the pain scale scores and a statistically significant negative relationship between the pain scale score and the ANI. CONCLUSIONS: The ANI device can be used safely and constantly for the objective assessment of postoperative pain in pediatric patients.

Peri-operative multimodal monitoring: a real need or a luxury?

The present case of a patient with several co-morbidities undergoing complex vitrectomy under peribulbar block and sedation with Target Controlled Infusion (TCI of propofol and dexmedetomidine with EEG and Analgesia Nociception Index (ANI) monitoring illustrates the benefits of multimodal monitoring to differentiate the effect of hypnotic and antinociceptive drugs.It is highlighted the delta-alpha electroencephalographic pattern showing adequate sedation, the beta arousal pattern in the EEG concommitant to decrease in the ANI translating insufficient anti-nociception.

Analgesia nociception index and high frequency variability index: promising indicators of relative parasympathetic tone.

At present, there is no objective and absolute measure of nociception, although various monitoring techniques have been developed. One such technique is the Analgesia Nociception Index (ANI), which is calculated from heart rate variability that reflects the relative parasympathetic tone. ANI is expressed on a non-unit scale of 0-100 (100 indicates maximal relative parasympathetic tone). Several studies indicated that ANI-guided anesthesia may help reduce intraoperative opioid use. The usefulness of ANI in the intensive care unit (ICU) and during surgery has also been reported. However, some limitations of ANI have also been reported; for example, ANI is affected by emotions and some drugs. In 2022, a high frequency variability index (HFVI), which was renamed from ANI and uses the same algorithm as ANI, was commercialized; therefore, ANI/HFVI are currently in the spotlight. Unlike ANI, HFVI can be displayed along with other biometric information on the Root® monitor. ANI/HFVI monitoring may affect the prognosis of not only patients in the perioperative period but those in ICU, those who receive home medical care, or outpatients. In this article, we present an updated review on ANI that has been published in the last decade, introduce HFVI, and discuss the outlooks of ANI/HFVI.

Nociception monitors vs. standard practice for titration of opioid administration in general anesthesia: A meta-analysis of randomized controlled trials.

Background: Nociception monitors are being increasingly used during surgery, but their effectiveness in guiding intraoperative opioid administration is still uncertain. This meta-analysis of randomized controlled trials (RCTs) aimed to compare the effectiveness of nociception monitors vs. standard practice for opioid administration titration during general anesthesia. Methods: We searched the electronic databases of PubMed, EMBASE, Cochrane Library, Clinical Trial, and Web of Science from inception up to August 1, 2021, to identify relevant articles, and extracted the relevant data. Intraoperative opioid administration, extubation time, postoperative pain score, postoperative opioid consumption and postoperative nausea and vomiting (PONV) were compared between patients receiving nociception monitoring guidance and patients receiving standard management. The standardized mean difference (SMD), with 95% confidence interval (CI), was used to assess the significance of differences. The risk ratio (RR), with 95% CI, was used to assess the difference in incidence of PONV. Heterogeneity among the included trials was evaluated by the I 2 test. RevMan 5.3 software was used for statistical analysis. Results: A total of 21 RCTs (with 1957 patients) were included in the meta-analysis. Intraoperative opioid administration was significantly lower in patients receiving nociception monitor-guided analgesia than in patients receiving standard management (SMD, -0.71; 95% CI, -1.07 to -0.36; P < 0.001). However, pain scores and postoperative opioid consumption were not significantly higher in the former group. Considerable heterogeneity was found among the studies (92%). Extubation time was significantly shorter (SMD, -0.22; 95% CI, -0.41 to -0.03; P = 0.02) and the incidence of PONV significantly lower (RR, 0.78; 95% CI, 0.61 to 1.00; P = 0.05) in patients receiving nociception monitoring guidance. Conclusions: Intraoperative nociception monitoring guidance may reduce intraoperative opioid administration and appears to be a viable strategy for intraoperative titration of opioids. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=273619, identifier: CRD42019129776.

Comparison of Deep Learning Algorithms in Predicting Expert Assessments of Pain Scores during Surgical Operations Using Analgesia Nociception Index.

There are many surgical operations performed daily in operation rooms worldwide. Adequate anesthesia is needed during an operation. Besides hypnosis, adequate analgesia is critical to prevent autonomic reactions. Clinical experience and vital signs are usually used to adjust the dosage of analgesics. Analgesia nociception index (ANI), which ranges from 0 to 100, is derived from heart rate variability (HRV) via electrocardiogram (ECG) signals, for pain evaluation in a non-invasive manner. It represents parasympathetic activity. In this study, we compared the performance of multilayer perceptron (MLP) and long short-term memory (LSTM) algorithms in predicting expert assessment of pain score (EAPS) based on patient's HRV during surgery. The objective of this study was to analyze how deep learning models differed from the medical doctors' predictions of EAPS. As the input and output features of the deep learning models, the opposites of ANI and EAPS were used. This study included 80 patients who underwent operations at National Taiwan University Hospital. Using MLP and LSTM, a holdout method was first applied to 60 training patients, 10 validation patients, and 10 testing patients. As compared to the LSTM model, which had a testing mean absolute error (MAE) of 2.633 ± 0.542, the MLP model had a testing MAE of 2.490 ± 0.522, with a more appropriate shape of its prediction curves. The model based on MLP was selected as the best. Using MLP, a seven-fold cross validation method was then applied. The first fold had the lowest testing MAE of 2.460 ± 0.634, while the overall MAE for the seven-fold cross validation method was 2.848 ± 0.308. In conclusion, HRV analysis using MLP algorithm had a good correlation with EAPS; therefore, it can play role as a continuous monitor to predict intraoperative pain levels, to assist physicians in adjusting analgesic agent dosage. Further studies may consider obtaining more input features, such as photoplethysmography (PPG) and other kinds of continuous variable, to improve the prediction performance.

Exactitud diagnóstica del índice de nocicepción analgesia para la evaluación del dolor en pacientes críticos / Diagnostic accuracy of analgesia nociception index for pain assessment in critically ill patients / Precisão diagnóstica do índice de analgesia nocicepção para avaliação da dor em pacientes críticos

Resumen: La evaluación de la presencia de dolor en el enfermo sometido a sedación profunda y ventilación mecánica es posible a través de escalas que se basan en datos clínicos indirectos. El índice de nocicepción analgesia (ANI) es utilizado en enfermos anestesiados en la sala quirúrgica. La información sobre su eficacia en los enfermos críticos es escasa. Este trabajo prospectivo, observacional y analítico evalúa el rendimiento diagnóstico de ANI para detectar dolor en los enfermos críticos en ventilación mecánica, sedados con RASS de -3 a -1. Como estándar se utilizaron dos escalas clínicas (BPS y CPOT) aplicadas por médicos y enfermeras de manera simultánea a la medición de ANI, en cuatro ocasiones durante un periodo de 12 minutos. En 23 enfermos y 224 mediciones, la capacidad discriminativa medida a través de áreas por debajo de curvas ROC osciló entre 0.779 y 0.817. El puntaje de ANI con mejor capacidad diagnóstica osciló entre 52 y 55. Utilizando el valor umbral de 50, la sensibilidad osciló entre 0.418 y 0.524, la especificidad entre 0.910 y 0.980. Se reportan los valores predictivos y las razones de verosimilitud. Los cambios en ANI y las escalas, originados por procedimientos durante la medición, tuvieron una concordancia que osciló entre 28 y 41%. Los resultados identifican una tecnología con potencial para su utilización en el enfermo crítico. Son necesarios más estudios que corroboren nuestros resultados.

Abstract: The assessment of pain in patients undergoing deep sedation and mechanical ventilation is possible through scales that are based on indirect clinical data. The Analgesia Nociception Index (ANI) is used in anesthetized patients in the operating room. Information on its efficacy in critically ill patients is scarce. This prospective, observational and analytical study evaluates the diagnostic performance of ANI to detect pain in critically ill patients on mechanical ventilation and sedated (RASS from -3 to -1). Two clinical scales (BPS and CPOT) were used as standard, applied by doctors and nurses simultaneously to the ANI measurement, on four occasions during a 12-minute period. In 23 patients and 224 measurements, the discriminative capacity measured through ROC curve areas ranged between 0.779 and 0.817. The ANI score with the best diagnostic capacity ranged between 52 and 55. Using the threshold value of 50, the sensitivity ranged between 0.418 and 0.524, the specificity between 0.910 and 0.980. Predictive values and likelihood ratios are reported. The changes in ANI and the scales, originated by procedures during the measurement, had a concordance that ranged between 28 and 41%. The results identify a technology with potential for use in the critically ill. More studies are needed to corroborate our results.

Resumo: A avaliação da presença de dor em pacientes submetidos à sedação profunda e ventilação mecânica é possível por meio de escalas baseadas em dados clínicos indiretos. O índice de analgesia nocicepção (ANI) é utilizado em pacientes anestesiados na sala de cirurgia. As informações sobre sua eficácia em pacientes críticos são escassas. Este estudo prospectivo, observacional e analítico avalia o desempenho diagnóstico do ANI para detectar dor em pacientes críticos em ventilação mecânica, sedados com RASS de -3 a -1. Como padrão, foram utilizadas duas escalas clínicas (BPS e CPOT) aplicadas por médicos e enfermeiros simultaneamente à medida do ANI, em quatro ocasiões durante um período de 12 minutos. Em 23 pacientes e 224 medidas, a capacidade discriminativa medida através das áreas sob as curvas ROC variou entre 0.779 e 0.817. O escore ANI com melhor capacidade diagnóstica variou entre 52 e 55. Utilizando o valor limite de 50, a sensibilidade variou entre 0.418 e 0.524, a especificidade entre 0.910 e 0.980. Relatam-se valores preditivos e razões de verossimilhança. As alterações no ANI e nas escalas, causadas por procedimentos durante a medição, tiveram uma concordância que variou entre 28 e 41%. Os resultados identificam uma tecnologia com potencial para uso em pacientes críticos. Mais estudos são necessários para corroborar nossos resultados.

Analgesia Nociception Index-Guided Remifentanil versus Standard Care during Propofol Anesthesia: A Randomized Controlled Trial.

The clinical benefits to be expected from intraoperative nociception monitors are currently under investigation. Among these devices, the Analgesia Nociception-Index (ANI) has shown promising results under sevoflurane anesthesia. Our study investigated ANI-guided remifentanil administration under propofol anesthesia. We hypothesized that ANI guidance would result in reduced remifentanil consumption compared with standard management. This prospective, randomized, controlled, single-blinded, bi-centric study included women undergoing elective gynecologic surgery under target-controlled infusion of propofol and remifentanil. Patients were randomly assigned to an ANI or Standard group. In the ANI group, remifentanil target concentration was adjusted by 0.5 ng mL-1 steps every 5 min according to the ANI value. In the Standard group, remifentanil was managed according to standard practice. Our primary objective was to compare remifentanil consumption between the groups. Our secondary objectives were to compare the quality of anesthesia, postoperative analgesia and the incidence of chronic pain. Eighty patients were included. Remifentanil consumption was lower in the ANI group: 4.4 (3.3; 5.7) vs. 5.8 (4.9; 7.1) µg kg-1 h-1 (difference = -1.4 (95% CI, -2.6 to -0.2), p = 0.0026). Propofol consumption was not different between the groups. Postoperative pain scores were low in both groups. There was no difference in morphine consumption 24 h after surgery. The proportion of patients reporting pain 3 months after surgery was 18.8% in the ANI group and 30.8% in the Standard group (difference = -12.0 (95% CI, -32.2 to 9.2)). ANI guidance resulted in lower remifentanil consumption compared with standard practice under propofol anesthesia. There was no difference in short- or long-term postoperative analgesia.

Prediction of reactivity during tracheal intubation by pre-laryngoscopy tetanus-induced ANI variation.

The ANI is a nociception monitor based on the high frequency parts of heart rate variability. Tracheal intubation may induce potentially deleterious hemodynamic disturbances or motor reactions if analgesia is inadequate. We investigated whether ANI modification generated by a standardized moderate short tetanic stimulation performed before laryngoscopy could predict hemodynamic or somatic reactions to subsequent intubation. We designed a prospective, interventional, monocentric, pilot study. Regional ethics board approved the study, written informed consent was obtained from each participant. Before laryngoscopy, under steady-state total intravenous anaesthesia with propofol and remifentanil, the ulnar nerve was stimulated with a 5 s tetanus (70 mA, 50 Hz). After another steady-state period, orotracheal intubation was performed. ANI variation, hemodynamic parameters and somatic reactions associated with tetanus and intubation were collected. To assess the predictability of hemodynamic or somatic reaction during laryngoscopy by tetanus-induced ANI variation, we calculated the area under the corresponding Receiver Operating Characteristic curve (AUCROC) and the 95% confidence intervals. Thirty-five patients were analyzed. ANI decreased by 21 ± 17 after tetanus. Regarding the ability of tetanus-induced ANI variation to predict hemodynamic or somatic reactions during subsequent intubation, the AUCROCs [95% CI] were 0.61 [0.41-0.81] and 0.52 [0.31-0.72] respectively. ANI varied after a short moderate tetanic stimulation performed before laryngoscopy but this variation was not predictive of a hemodynamic or somatic reaction during intubation.Trial registration NCT04354311, April 20th 2020, retrospectively registered.

Evaluation of the Analgesia Nociception Index and videopupillometry to predict post-tonsillectomy morphine requirements in children: a single-centre, prospective interventional study.

Background: Tonsil surgery causes significant and challenging postoperative pain. The Analgesia Nociception Index (ANI) and videopupillometry are two techniques of interest to monitor nociception in adults and may predict postoperative morphine requirements. We hypothesised that these techniques could predict the need for morphine after tonsillectomy in children. The main objective was to assess the prognostic significance of ANI and videopupillometry, measured at the end of surgery, on morphine consumption determined by a Face, Legs, Activity, Cry, Consolability (FLACC) scale score >3 in the Post Anesthesia Care Unit (PACU). Methods: A single-centre, prospective, interventional study evaluating children between 2 and 7 yr old undergoing tonsil surgery was performed. ANI and videopupillometry with tetanic stimulation were measured under general anaesthesia 4 min after the end of the surgical procedure. Each child was evaluated every 10 min by a nurse using the FLACC scale in the PACU and blinded to the measurements performed in the operating theatre. Results: Eighty-nine children were analysed and 39 (44%) received morphine in the PACU. Neither ANI values nor videopupillometry values were predictive of postoperative morphine consumption (areas under the receiver operating characteristic curve 0.54, 95% confidence interval [CI; 0.42-0.65], and P=0.57; and 0.52, 95% CI [0.41-0.63], and P=0.69, respectively). Neither ANI values nor videopupillometry values were correlated to the maximum FLACC scale score in the PACU with ρ=0.04 (P=0.71) and ρ=0.06 (P=0.57), respectively. Conclusions: Neither ANI nor videopupillometry performed at the end of surgery can predict morphine consumption in the PACU in children undergoing tonsillectomy.