Daily Anesthesiology Research Analysis
Three anesthesiology studies stand out today: a randomized trial shows remimazolam produces distinct EEG signatures and slower recovery versus propofol, a double-blind RCT finds perineural dexamethasone in an adductor canal block lowers persistent postsurgical pain after ACL reconstruction, and an EEG-monitor benchmarking study demonstrates depth-of-anesthesia indices reflect emergence trajectories linked to postoperative neurocognitive risk. Together, they advance precision neuro-monitoring and
Summary
Three anesthesiology studies stand out today: a randomized trial shows remimazolam produces distinct EEG signatures and slower recovery versus propofol, a double-blind RCT finds perineural dexamethasone in an adductor canal block lowers persistent postsurgical pain after ACL reconstruction, and an EEG-monitor benchmarking study demonstrates depth-of-anesthesia indices reflect emergence trajectories linked to postoperative neurocognitive risk. Together, they advance precision neuro-monitoring and multimodal analgesia strategies.
Research Themes
- Precision EEG monitoring to predict recovery and neurocognitive risk
- Regional anesthesia adjuvants to prevent persistent postsurgical pain
- Translating spectral EEG trajectories into actionable depth-of-anesthesia indices
Selected Articles
1. Electroencephalogram Correlates of Delayed Emergence After Remimazolam-Induced Anesthesia Compared to Propofol.
In a randomized comparison of 48 patients, remimazolam produced higher theta/alpha EEG power, lower PLE/PLI connectivity, lower PACU PSI values, and a significantly slower time to Aldrete 9 than propofol. Time to recovery correlated strongly with alpha-band PLE (r = −0.78) and PLI (r = 0.69), indicating EEG signatures that track delayed emergence under remimazolam.
Impact: This RCT reveals mechanistic EEG markers linked to delayed emergence with remimazolam, informing agent selection and real-time monitoring strategies for safe recovery.
Clinical Implications: When using remimazolam, anticipate slower emergence and consider EEG-informed titration and recovery planning; integrating PLE/PLI and PSI trends may improve early detection of delayed recovery and guide PACU resource allocation.
Key Findings
- Remimazolam showed higher theta (EO) and alpha (EC/EO) EEG power during emergence than propofol (P ≤ .018 to <.001).
- Functional connectivity (PLE) in alpha/beta bands was lower with remimazolam (P ≤ .016), indicating altered network dynamics.
- PACU PSI values were lower with remimazolam (EC 65.1 vs 82.4; EO 72.35 vs 83.53) and time to Aldrete 9 was significantly longer (median difference 17.5 min, P < .001).
- Recovery time under remimazolam correlated with alpha-band PLE (r = −0.78) and PLI (r = 0.69).
Methodological Strengths
- Randomized drug assignment with standardized surgery (laparoscopic cholecystectomy).
- Multimodal EEG analysis (power spectra, PLE/PLI) with clinical correlation (PSI, Aldrete).
Limitations
- Single-center, small sample size (n=48) limits generalizability.
- Prefrontal EEG only; long-term neurocognitive outcomes were not assessed.
Future Directions: Validate EEG-derived recovery markers in larger multicenter trials, assess dose-response and adjunct reversal strategies, and link intraoperative EEG dynamics to postoperative neurocognitive outcomes.
BACKGROUND: Delayed emergence from anesthesia presents clinical challenges, including prolonged stays in the postanesthesia care unit (PACU). The neurobiological mechanisms underlying delayed emergence, particularly in remimazolam-induced anesthesia, remain poorly understood. This study aimed to explore patterns of brain electrical activity of delayed emergence in remimazolam-induced anesthesia by comparing dynamic changes in electroencephalogram (EEG) activity under various anesthesia states of remimazolam and propofol, focusing on the prefrontal region. METHODS: Forty-eight patients (age >18) who underwent laparoscopic cholecystectomy randomly received remimazolam- or propofol-induced general anesthesia. Power spectrogram analysis and functional connectivity measures, phase lag entropy (PLE) and phase lag index (PLI), were used to the prefrontal EEG data collected at baseline, unconsciousness, and emergence. Correlation between EEG measures and Patient State Index (PSI) at PACU, as well as time to Aldrete 9, were compared. RESULTS: During emergence from anesthesia, EEG power revealed that the remimazolam group had higher powers than the propofol group in theta band during eyes-open (EO) (mean of 2.933 [standard deviation of 5.762] vs -2.342 [4.869]; P-value of 0.018 with independent 2-sample t test), and in the alpha band during eyes-closed (EC) (5.821 [7.35] vs -2.399 [4.53]; P < .001) and EO (4.84 [6.411] vs -3.613 [4.556]; P < .001). Conversely, the functional connectivity result showed lower PLE in the alpha band during EC (0.619 [0.0338] vs 0.684 [0.0392]; P < .0001) and EO (0.651 [0.0358] vs 0.692 [0.0428]; P = .015), and in the beta band during EC (0.682 [0.0308] vs 0.712 [0.0236]; P = .016) and EO (0.695 [0.0236] vs 0.725 [0.0195]; P < .001). In line with this, the remimazolam group had lower PSI values at PACU during EC (65.10 [14.67] vs 82.40 [6.678]; P < .0001) and EO (72.35 [12.55] vs 83.53 [6.632]; P = .006) and were slower to reach Aldrete score of 9 (median difference of 17.5; interquartile range of [0.0-21.0]; P < .001). Delayed consciousness recovery (time to Aldrete 9) under remimazolam was significantly correlated with PLE (Pearson's correlation = -.78, P < .0001) and PLI (Pearson's correlation =.69, P = .028) in the alpha band during deep anesthesia. CONCLUSIONS: Dynamic changes in prefrontal EEG during recovery and the correlation analyses show the potential of EEG in reflecting distinct consciousness recovery profiles between 2 drugs-slower recovery under remimazolam anesthesia. This suggests an association of EEG parameters with a unique behavioral profile of remimazolam, especially reflecting progressive changes in cerebral activity during recovery.
2. Dexamethasone as an additive to bupivacaine in an ultrasound-guided adductor canal block for the management of persistent pain after arthroscopic reconstruction of the anterior cruciate ligament: a randomized, double-blind study.
In a double-blind RCT of 90 ACL reconstruction patients, adding 8 mg perineural dexamethasone to 0.25% bupivacaine in an adductor canal block prolonged analgesia (10 h vs 6 h), reduced 24 h meperidine use, lowered 6–12 h pain scores, and decreased the 3‑month PPSP incidence (20% vs 33%) and severity.
Impact: Targets a clinically meaningful endpoint—persistent postsurgical pain—demonstrating a practical, low-cost intervention with measurable benefits in recovery and opioid stewardship.
Clinical Implications: Consider perineural dexamethasone as an adjuvant in adductor canal blocks for ACL reconstruction to extend analgesia, reduce early opioid consumption, and lower the risk of 3‑month PPSP.
Key Findings
- Analgesia duration increased from 6 ± 1 h to 10 ± 3 h with perineural dexamethasone.
- 24-hour meperidine consumption decreased (65 ± 23 mg vs 104 ± 27 mg).
- Pain scores at 6 and 12 hours were lower in the dexamethasone group.
- PPSP incidence at 3 months decreased (20% vs 33%), with lower severity and codeine use.
Methodological Strengths
- Randomized, double-blind design with ultrasound-guided standardized block technique.
- Clinically meaningful outcomes including 3-month PPSP and opioid consumption.
Limitations
- Single-center study; generalizability across practices and analgesic formularies may vary.
- Use of meperidine and codeine may not reflect all contemporary opioid protocols.
Future Directions: Replicate in multicenter trials, compare steroid doses and alternatives, and assess functional recovery, neuropathic features, and long-term quality of life.
BACKGROUND: Pain is a protective response to noxious stimuli to prevent further damage. The surgical incision results in several events that lead to pain that outlasts its benefits. Persistent postsurgical pain (PPSP) is defined as "pain that persists for three months after surgical intervention. OBJECTIVES: To investigate the effect of dexamethasone as an adjuvant to adductor canal block on persistent postsurgical pain after ACL reconstruction. PATIENTS AND METHODS: Ninety patients who underwent arthroscopic reconstruction of the anterior cruciate ligament and who completed the study were randomly allocated into two groups. Forty-five patients in each group received ultrasound-guided adductor canal block at the end of surgery. G I (Dexa group): Forty-five patients received a 20 ml mixture of 0.25% bupivacaine and 8 mg dexamethasone (2 ml). G II (control group): Patients received a 20 ml mixture of 0.25% bupivacaine and 2 ml of normal saline. RESULTS: No significant differences in demographic data, intraoperative hemodynamics or surgery duration were detected between the two groups. The duration of postoperative analgesia was significantly longer in the dexamethasone group (10 h ± 3 vs. 6 h ± 1) than in the control group. Additionally, 24 h postoperative consumption of meperidine was significantly lower in the dexamethasone group (65 ± 23 vs. 104 ± 27) than in the control group. Postoperative VAS scores at 6 and 12 h were also lower in the dexamethasone group than in the control group. Three-month follow-up revealed a significantly lower incidence of PPSP in the dexamethasone group (20% versus 33% in the control group). Moreover, the severity of PPSP was significantly lower in the dexamethasone group than in the control group. Additionally, Codeine consumption was significantly lower in the dexamethasone group than in the control group. CONCLUSION: Perineural dexamethasone in ultrasound-guided adductor canal block reduced the severity of PPSP and opioid analgesia consumption in the first three months following arthroscopic reconstruction of the ACL. CLINICAL TRIAL REGISTRATION: The study was registered on clinical trial registration (NCT04631822) in October 2020.
3. The Effect of Electroencephalographic Trajectory During Anesthesia Emergence on the Indices Monitoring the Hypnotic Component.
Replaying 59 emergence EEGs into four commercial monitors showed that index trajectories (SE, PSI, qCON, BIS) mirror spectral EEG emergence patterns. SE/PSI differentiated Traj Ref vs Abrupt, while qCON/PSI/BIS distinguished Ref vs High, supporting practical identification of PND‑linked emergence trajectories at the bedside.
Impact: Bridges mechanistic EEG trajectories with widely used clinical indices, enabling risk-aware emergence monitoring without specialized spectral analysis.
Clinical Implications: Monitoring the shape and timing of index trajectories (SE/PSI/qCON/BIS) during emergence may flag high-risk PND trajectories (Abrupt/High) and prompt mitigation strategies before PACU transfer.
Key Findings
- SE and PSI significantly differentiated Traj Ref vs Traj Abrupt across much of emergence (linear rise vs dip-then-jump pattern).
- qCON, PSI, and BIS significantly differentiated Traj Ref vs Traj High, particularly early in emergence, due to high starting indices in nSWA.
- Index courses across devices reflected underlying spectral EEG patterns tied to PND risk in prior work.
Methodological Strengths
- Device-agnostic EEG replay enabling standardized comparison across four commercial monitors.
- Predefined trajectory groups grounded in prior PND-associated spectral classifications.
Limitations
- Non-random selection by trajectory and modest sample size (n=59).
- Offline EEG replay; no direct PND outcomes assessed in this study.
Future Directions: Prospective validation linking index trajectories to PND incidence and testing trajectory-guided emergence protocols across devices and patient populations.
BACKGROUND: Postoperative neurocognitive disorders (PNDs) are frequent and serious complications that cause an enormous social and economic burden. A previous study demonstrated that certain electroencephalographic (EEG) patterns during emergence from general anesthesia are associated with a higher risk for PND. Compared to patients demonstrating the most favorable trajectory (Traj Ref: delta-dominant slow-wave anesthesia (ddSWA)→spindle-dominant SWA (sdSWA)→non-SWA (nSWA)→wake), patients presenting Traj Abrupt (ddSWA→wake) had 4-fold increased odds to develop PND and patients with Traj High (nSWA→wake) had 8-fold increased odds of developing PND. We hypothesized that commonly used neuromonitoring devices (state entropy [SE], quantium consciousness index [qCON], bispectral index [BIS], and Patient State Index [PSI]) can differentiate between the various trajectories. METHODS: From the original database of the study by Hesse et al, we analyzed 59 EEGs from patients emerging from general anesthesia. They were selected according to their trajectory. We included 19 patients who had shown the most favorable trajectory (Traj Ref), 20 who had demonstrated Traj Abrupt, and 20 who had followed Traj High. To evaluate the performance of the neuromonitoring devices, we replayed the patients' EEGs to the monitors using an EEG player. We compared the index values for the 3 different trajectories (Traj Ref, Traj Abrupt, and Traj High) generated by the different monitoring devices, respectively. Additionally, we evaluated the correlation between the monitoring devices. RESULTS: SE and PSI were able to resolve significant differences between Traj Ref and Traj Abrupt during a major part of emergence. Traj Ref showed an almost linear increase of index values, whereas Traj Abrupt led to an episode of low index values followed by a sudden increase. However, when comparing Traj Ref vs Traj High, qCON, PSI, and BIS were the indices showing significant differences, especially at the beginning of emergence. Patients representing Traj Ref patterns had significantly lower index values than those depicting Traj High. Due to the Traj High cases starting in nSWA, their indices were already high at the start of emergence. CONCLUSIONS: Our analysis revealed that the course of the different indices reflects spectral EEG patterns during the emergence from general anesthesia. Considering certain emergence trajectories associated with a higher risk of developing PND, our approach might enable the anesthetist to identify patients particularly susceptible to PND by observing the course of index values before admission to the postanesthesia care unit.