Heart rate variability analysis for arterial hypertension etiological diagnosis during surgical procedures under tourniquet

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.

Comparison of Three Normalization Methods in Monitoring Analgesic Depth with Photoplethysmographic Diastolic Interval

The purpose of the present study was to investigate the ability of three different normalization methods, namely root mean square (RMS) value, mean value, and maximum which referred to pulse beat interval (PBI), based on photoplethysmographic diastolic interval (DI) in response to laryngeal mask airway (LMA) insertion under various remifentanil concentrations during general anesthesia. Sixty patients were randomly allocated to one of the four groups to receive a possible remifentanil effect-compartment target concentration (Ce_remi) of 0, 1, 3, or 5 ng/ml, and an effect-compartment target controlled infusion of propofol to maintain the state entropy (SE) at 40~60. Three normalized measures DI_RMS, DI_Mean, and DIPBI were compared with the DI values without normalization. Before LMA insertion, only DI showed a considerable correlation with remifentanil concentrations. DI_RMS and DI_Mean performed better than DI in discriminating 'insufficient' concentrations (0 and 1 ng/ml) from 'sufficient' concentrations (3 and 5 ng/ml). DIRMS was superior to all other variables in grading analgesic depth after nociceptive event occurred with PK value of 0.836. These results demonstrate that the normalization using RMS value, compared to using mean value and maximum, seems to provide a more effective approach for signal pre-processing.

Analgesia Nociception Index: Heart Rate Variability Analysis of Emotional Status

Background

Analgesia nociception index (ANI) has been developed for real-time pain measurement during a surgical procedure under general anesthesia. The index is based on heart rate variability and constitutes a measure of parasympathetic tone. In this paper, we hypothesized that this index could be used as a tool to investigate the process of emotional regulation of a human subject.

Materials and methods

Twenty adult volunteers were recruited for the study, wherein ANI response to the emotional stimulus was evaluated. An emotional stimulus was obtained through a 60-second music sound record from the song “Ala Gözlerini Sevdiğim Dilber,” performed by the Turkish rock band Badem. ANI measurements were obtained before the song presentation (T_pre), at the end of the record presentation (T0), and each minute thereafter until the end of the five-minute observation (T1-T5).

Results

Twenty participants were investigated; 10 males and 10 females. The mean age of the participants was 17.0 ± 0.9 (min: 16, max: 20). ANI measurements were significantly lower in T0 and T3 compared with T_pre (P = 0.009). The differences between other values were not statistically significant.

Conclusion

ANI can be used for assessment of parasympathetic changes related to the emotional state of conscious patients.

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

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

Automated analgesic drugs delivery guided by vagal tone evaluation: interest of the Analgesia Nociception Index (ANI)

Analgesic drugs delivery optimization constitutes one of the main objectives of modern anesthesia. Indeed, their over or under determination constitutes a risk for anesthetized patient in terms of hemodynamic reactivity or post-operative hyperalgesia. Nowadays, new physiological indexes allow anesthesiologists to evaluate the balance between the analgesia level and the noxious stimulus importance. ANI is an index related to the autonomic nervous system activity based on heart rate variability analysis. Its ability for the analgesia / nociception balance evaluation has been established bringing evidences about its helpfulness for analgesic drug delivery. In this article, we describe a device for automatic analgesic drugs administration based on the ANI evolution during surgical procedures under general anesthesia. We hypothesized that such a device could improve the quality and safety of anesthesia by reducing adverse cardiovascular events and delivered analgesic drugs doses.

Evaluation of techniques for estimating the power spectral density of RR-intervals under paced respiration conditions

Heart rate variability (HRV) analysis is increasingly used in anaesthesia and intensive care monitoring of spontaneous breathing and mechanical ventilated patients. In the frequency domain, different estimation methods of the power spectral density (PSD) of RR-intervals lead to different results. Therefore, we investigated the PSD estimates of fast Fourier transform (FFT), autoregressive modeling (AR) and Lomb-Scargle periodogram (LSP) for 25 young healthy subjects subjected to metronomic breathing. The optimum method for determination of HRV spectral parameters under paced respiration was identified by evaluating the relative error (RE) and the root mean square relative error (RMSRE) for each breathing frequency (BF) and spectral estimation method. Additionally, the sympathovagal balance was investigated by calculating the low frequency/high frequency (LF/HF) ratio. Above 7 breaths per minute, all methods showed a significant increase in LF/HF ratio with increasing BF. On average, the RMSRE of FFT was lower than for LSP and AR. Therefore, under paced respiration conditions, estimating RR-interval PSD using FFT is recommend.