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

Using the nociception level index to compare the intraoperative antinociceptive effect of propofol and sevoflurane during clinical and experimental noxious stimulus in patients under general anesthesia

STUDY

Propofol and sevoflurane are two anesthetic agents widely used to induce and maintain general anesthesia (GA). Their intrinsic antinociceptive properties remain unclear and are still debated.

OBJECTIVE

To determine whether propofol presents stronger antinociceptive properties than sevoflurane using intraoperative clinical and experimental noxious stimulations and evaluating postoperative pain outcomes.

DESIGN

A prospective randomized monocentric trial.

SETTING

Perioperative care.

PATIENTS

60 adult patients with ASA status I to III who underwent elective abdominal laparoscopic surgery under GA were randomized either in propofol or sevoflurane group to induce and maintain GA.

INTERVENTIONS

We used clinical and experimental noxious stimulations (intubation, tetanic stimulation) to assess the antinociceptive properties of propofol and sevoflurane in patients under GA and monitored using the NOL index, BIS index, heart rate, and mean arterial blood pressure.

MEASUREMENTS

We measured the difference in the NOL index alterations after intubation and tetanic stimulation during either intravenous anesthesia (propofol) or inhaled anesthesia (sevoflurane). We also intraoperatively measured the NOL index and remifentanil consumption and recorded postoperative pain scores and opioid consumption in the post-anesthesia care unit. Intraoperative management was standardized by targeting similar values of depth of anesthesia (BIS index), hemodynamic (HR and MAP), NOL index values (below the threshold of 20), same multimodal analgesia and type of surgery.

MAIN RESULTS

We found the antinociceptive properties of propofol and sevoflurane similar. The only minor difference was after tetanic stimulation: the delta NOL was higher in the sevoflurane group (39 ± 13 for the propofol group versus 47 ± 15 for sevoflurane; P = 0.04). Intraoperative and postoperative pain outcomes and opioid consumption were similar between groups.

CONCLUSIONS

Despite a precise intraoperative experimental and clinical protocol using the NOL index, propofol does not provide a higher level of antinociception during anesthesia or analgesia after surgery when compared to sevoflurane. Anesthesiologists may prefer propofol over sevoflurane to reduce PONV or anesthesia-related pollution, but not for superior antinociceptive properties.

Does heart rate variability using the Newborn Infant Parasympathetic Evaluation index identify postsurgical pain levels and emergence delirium in toddlers? A prospective observational study

PURPOSE

Children recovering from anesthesia commonly experience early postoperative negative behaviour, caused by pain and emergence delirium. Differentiating the two is challenging in young children. Perioperative pain influences the heart rate variability-derived Newborn Infant Parasympathetic Evaluation (NIPE) index and may also affect emergence delirium. We sought to investigate whether the perioperative NIPE index can discriminate between mild, moderate, or severe pain levels and can detect emergence delirium.

METHODS

This prospective observational study enrolled children aged three years or younger undergoing elective adenotonsillectomy, tonsillectomy, or adenoidectomy. The NIPE index, the Faces, Legs, Activity, Cry, Consolability (FLACC) score, and the Pediatric Anesthesia Emergence Delirium (PAED) score were recorded in the postanesthesia care unit (PACU). The primary aim was to investigate the relationship between the postoperative NIPE index and postoperative pain severity. The secondary aims were to evaluate the association between the NIPE index and emergence delirium (PAED ≥ 10) and its delirium-specific (ED-I) and pain-specific (ED-II) components.

RESULTS

Sixty-nine children were recruited. In the PACU, the mean (standard deviation [SD]) NIPE values in children experiencing moderate and severe pain were 50 (12) and 49 (14), respectively. These values were significantly lower than the mean (SD) value of 64 (13) observed in children with mild pain (mean difference moderate vs no/mild pain, -14; 95% confidence interval [CI], -17 to -11; P < 0.001, and mean difference severe vs no/mild pain, -17; 95% CI, -20 to -14; P < 0.001, respectively). The NIPE index was significantly lower in children experiencing pain-specific ED-II (mean [SD] NIPE instantaneous [NIPEi] for ED-II 49 [10] vs no ED-II 55 [13]; mean difference, -6; 95% CI, -11 to -2; P = 0.009). The NIPE index was unable to detect emergence delirium (mean [SD] NIPEi for ED, 54 [15] vs no ED, 51 [10]; mean difference, 3; 95% CI, -2 to 8; P = 0.23) or the delirium-specific component ED-I (mean [SD] NIPEi for ED-I, 55 [15] vs no ED-I, 51 [11]; mean difference, 4; 95% CI, 0 to 8; P = 0.06).

CONCLUSION

The NIPE index can identify moderate and severe postoperative pain after adenotonsillectomy but not emergence delirium in children aged three years and younger. This discrimination can be valuable in the early postoperative phase when the differentiation between pain and emergence delirium is difficult.

STUDY REGISTRATION

ClinicalTrials.gov ( NCT04909060 ); first submitted 26 May 2021.

Fine-tuning the needle: analysis of acupuncturist response to alarming events during gynecological oncology surgery

OBJECTIVE

Examining an intra-operative acupuncture/acupressure setting, with real-time "fine-tuning" in response to alarming events (AEvs) during gynecological oncology surgery.

METHODS

Narratives of acupuncturists providing intraoperative acupuncture during gynecological oncology surgery were qualitatively analyzed. These described real time "fine-tuning" in response to AEvs during surgery, identified through hemodynamic changes (e.g., systolic/diastolic arterial pressure); bispectral index (BIS) elevation; and feedback from surgeons and anesthesiologists. Documentation of acupuncturist responses to AEvs was addressed as well.

RESULTS

Of the 48 patients in the cohort, 33 had at least one intraoperative AEv (69%), of which 30 were undergoing laparoscopic surgery and 18 laparotomies. A total of 77 AEvs were documented throughout surgery (range 1-7; mean: 2.3 events per patient), identified through increased (63 events) or decreased (8) mean arterial pressure (MAP); increased BIS levels (2), or other hemodynamic parameters (4). Integrative oncology interventions implemented in response to AEs included acupressure alone (59); combining acupressure with acupuncture (10); or acupuncture alone (4). In 54 (70%) events, documentation was provided from beginning to conclusion of the AEv, with a mean duration of 9.7 min, with 32 events including a documented anesthesiologist intervention.

CONCLUSION

The present study demonstrated the feasibility of intraoperative acupuncture with acupressure, with ongoing "fine-tuning" to AEvs identified through objective pain-related parameters (MAP, heart rate and BIS) and real-time input from surgeons and anesthesiologists. Documentation of the intraoperative IO practitioner's response to these AEvs is important, and should be addressed in future research of the innovative integrative model of care.

TRIAL REGISTRATION NUMBER

CMC-18-0037 (Carmel Medical Center, June 11, 2018).

Depth of Anesthesia and Nociception Monitoring: Current State and Vision For 2050

Anesthesia objectives have evolved into combining hypnosis, amnesia, analgesia, paralysis, and suppression of the sympathetic autonomic nervous system. Technological improvements have led to new monitoring strategies, aimed at translating a qualitative physiological state into quantitative metrics, but the optimal strategies for depth of anesthesia (DoA) and analgesia monitoring continue to stimulate debate. Historically, DoA monitoring used patient's movement as a surrogate of awareness. Pharmacokinetic models and metrics, including minimum alveolar concentration for inhaled anesthetics and target-controlled infusion models for intravenous anesthesia, provided further insights to clinicians, but electroencephalography and its derivatives (processed EEG; pEEG) offer the potential for personalization of anesthesia care. Current studies appear to affirm that pEEG monitoring decreases the quantity of anesthetics administered, diminishes postanesthesia care unit duration, and may reduce the occurrence of postoperative delirium (notwithstanding the difficulties of defining this condition). Major trials are underway to further elucidate the impact on postoperative cognitive dysfunction. In this manuscript, we discuss the Bispectral (BIS) index, Narcotrend monitor, Patient State Index, entropy-based monitoring, and Neurosense monitor, as well as middle latency evoked auditory potential, before exploring how these technologies could evolve in the upcoming years. In contrast to developments in pEEG monitors, nociception monitors remain by comparison underdeveloped and underutilized. Just as with anesthetic agents, excessive analgesia can lead to harmful side effects, whereas inadequate analgesia is associated with increased stress response, poorer hemodynamic conditions and coagulation, metabolic, and immune system dysregulation. Broadly, 3 distinct monitoring strategies have emerged: motor reflex, central nervous system, and autonomic nervous system monitoring. Generally, nociceptive monitors outperform basic clinical vital sign monitoring in reducing perioperative opioid use. This manuscript describes pupillometry, surgical pleth index, analgesia nociception index, and nociception level index, and suggest how future developments could impact their use. The final section of this review explores the profound implications of future monitoring technologies on anesthesiology practice and envisages 3 transformative scenarios: helping in creation of an optimal analgesic drug, the advent of bidirectional neuron-microelectronic interfaces, and the synergistic combination of hypnosis and virtual reality.

Effect of the Location of Tetanic Stimulation on Autonomic Responses: A Randomized Cross-Over Pilot Study

Background

Tetanic stimuli are used as standardized noxious inputs to investigate nociception. Previous studies have applied tetanic stimuli to various anatomical locations without validating that the resulting physiological responses were independent of the location where tetanic stimuli were applied. Our aim was to investigate the effects of three anatomical tetanic stimulus application sites on physiological variables reflecting autonomic nervous system responses as measured by photoplethysmography (PPG).

Methods

Under general anesthesia, a five second, 100 hertz, 70 milliamp tetanic stimulus was applied to the ulnar nerve, medial side of the tibia, and thorax (T5 dermatome) (N=12). The effect of tetanic stimuli on PPG-derived variables (AC, DC, and ACDC) and pulse rate at each stimulus location was determined using repeated-measures analysis of variance (ANOVA) followed by Dunnett's post hoc test. Maximum tetanic stimulus-induced changes in PPG-derived variables and pulse rates were compared among the three stimulus locations using ANOVA.

Results

AC and ACDC values of PPG decreased, and the DC values of PPG increased in response to tetanic stimuli-induced vasoconstriction at each location (p<0.001 for all). The maximum changes in the AC, ACDC, and DC values did not differ between locations (p=NS). There were no significant changes in pulse rate (p=NS).

Conclusion

The results showed that tetanic stimulation at either of these three locations provides the same autonomic nervous system responses, as measured by PPG.

Clinical Trial Registration

ClinicalTrials.gov; NCT03648853.

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.

A randomized-controlled trial assessing the effect of intraoperative acupuncture on anesthesia-related parameters during gynecological oncology surgery

CONTEXT AND OBJECTIVES

The present study examined the impact of intraoperative acupuncture on anesthesia-related parameters in patients undergoing gynecological oncology surgery.

METHODS

Participants underwent preoperative integrative oncology (IO) touch/relaxation treatments, followed by intraoperative acupuncture (Group A); preoperative IO treatments without acupuncture (Group B); or standard care only (Group C). Mean arterial pressure (MAP), heart rate (HR), MAP variability (mean of MAP standard deviation), bispectral index (BIS), and calculated blood pressure Average Real Variability (ARV) were measured intraoperatively.

RESULTS

A total of 91 patients participated: Group A, 41; Group B, 24; Group C, 26. Among patients undergoing open laparotomy, Group A showed lower and more stable MAP and HR compared to Group B, (MAP, p = 0.026; HR, p = 0.029) and Group C (MAP, p = 0.025). Mean BIS, from incision to suture closing, was lower in Group A (vs. controls, p = 0.024). In patients undergoing laparoscopic surgery, MAP was elevated within Group A (p = 0.026) throughout surgery, with MAP variability significantly higher in Group A (P = 0.023) and Group B (P = 0.013) 10 min post-incision (vs. pre-incision). All groups showed similar intraoperative and post-anesthesia use of analgesic medication.

CONCLUSION

Intraoperative acupuncture was shown to reduce and stabilize MAP and HR, and reduce BIS in gynecology oncology patients undergoing laparotomy, with no impact on perioperative analgesic medication use. In the laparoscopic setting, intraoperative acupuncture was associated with elevated MAP. Further research is needed to explore the hemodynamic and BIS-associated benefits and risks of intraoperative acupuncture, and the impact on the use of analgesic drugs in response to these changes.