Daily Anesthesiology Research Analysis
Analyzed 95 papers and selected 3 impactful papers.
Summary
Three impactful anesthesiology studies stand out today: a high-density EEG cohort identifies peak alpha frequency and spectral exponent as plausible biomarkers and mechanistic readouts for postoperative delirium; a large ICU cohort links esketamine exposure to secondary sclerosing cholangitis with dose-dependence; and a 57,000-patient audit finds higher aspiration incidence under a liberal clear-fluid fasting policy. Together, these data inform neurophysiology-driven monitoring, sedative risk stewardship, and perioperative fasting decisions.
Research Themes
- Neurophysiological biomarkers for postoperative delirium
- Sedative safety signals and ICU hepatobiliary complications
- Perioperative fasting policies and aspiration risk
Selected Articles
1. Peak alpha frequency and spectral exponent in postoperative delirium: a high-density EEG cohort study.
In 202 older adults undergoing major surgery with perioperative high-density EEG, postoperative delirium was associated with slower peak alpha frequency and a steeper spectral exponent relative to preoperative and 1-year values. These markers correlated with delirium severity, executive dysfunction, and inflammatory changes, supporting impaired excitatory–inhibitory balance as a mechanism.
Impact: Provides mechanistically grounded, noninvasive EEG biomarkers (PAF, SE) that track delirium dynamics and link to inflammation and cognition, enabling risk stratification and monitoring.
Clinical Implications: Incorporating PAF and SE into perioperative EEG monitoring could aid early delirium detection and mechanistic phenotyping, informing preventive strategies and trials targeting excitatory–inhibitory balance.
Key Findings
- Postoperative delirium showed slower peak alpha frequency and steeper spectral exponent versus preoperative and 1-year measurements.
- EEG changes correlated with delirium severity scales, executive function (TMT-B), and perioperative cytokine levels.
- Findings support increased inhibitory tone and slowed neuronal dynamics as mechanistic substrates of delirium.
Methodological Strengths
- High-density 256-channel EEG with longitudinal (pre-, post-, 1-year) acquisition
- Standardized delirium assessments and mixed-effects modeling linking EEG to cognitive and inflammatory measures
Limitations
- Single-center cohort with modest delirium cases (n=33) limits external generalizability
- Causality cannot be inferred; potential confounding by anesthesia type and perioperative factors
Future Directions: Prospective multicenter validation, integration with real-time EEG monitoring workflows, and interventional trials targeting excitatory–inhibitory balance based on PAF/SE phenotypes.
BACKGROUND: Present concepts around the neurophysiology of delirium suggest impairments in excitatory/inhibitory balance, leading to EEG slowing, altered synaptic activity and integration of information. We aim to clarify the mechanisms involved, hypothesising that, in postoperative delirium, the EEG peak alpha frequency (PAF; decreased peak frequency indicating slowing in alpha frequency) would slow and the spectral exponent (SE; a higher slope indicating an increased neural inhibitory tone) would be steeper compared with a baseline collected before surgery. The primary aim was to determine the association of PAF and SE with postoperative delirium. The secondary aim was to determine the association of perioperative changes in inflammation and executive function with PAF and SE. METHODS: High-density 256-channel EEG data were collected perioperatively (i.e. obtained pre-, post-, after 1-yr post-surgery) in a cohort study of 202 patients aged >65 yr undergoing major surgery conducted from 2015 to 2025 at a major quaternary care hospital. Thirty-three participants experienced postoperative delirium, 169 participants did not, with 113 participants followed up at the 1-yr interval. Linear mixed-effects modelling was conducted for PAF and SE estimates. Further analyses tested associations of PAF and SE with the Delirium Rating Scale, Trail Making Test-B (TMT-B) and plasma cytokine levels. RESULTS: After surgery, mean PAF was significantly slower and mean SE was significantly steeper compared with preoperative and 1-yr postoperative values ( CONCLUSIONS: Lower mean PAF and steeper SE are consistent with slower neuronal repolarisation and increased inhibition in delirium. PAF and SE estimates provide new information about delirium pathophysiology and could be further explored as noninvasive EEG biomarkers of detection and monitoring of delirium state.
2. Association of esketamine exposure with secondary sclerosing cholangitis in critically ill patients: a retrospective cohort analysis of 20,000 ICU cases.
In a 20,973-patient ICU cohort, esketamine exposure was independently and dose-dependently associated with secondary sclerosing cholangitis, alongside ICU length and COVID-19 status. A cholestasis-first screening approach also identified potentially unrecognized cases.
Impact: Identifies a plausible medication-related, dose-dependent harm signal for a devastating ICU cholangiopathy and proposes a pragmatic detection strategy.
Clinical Implications: Consider minimizing or avoiding ketamine/esketamine in high-risk ICU patients; implement cholestasis-first screening and early hepatobiliary imaging when cumulative esketamine doses accrue or cholestasis emerges.
Key Findings
- Esketamine exposure was independently associated with SSC-CIP with dose-dependency (OR 1.021 per gram).
- COVID-19 status (OR 20.6) and ICU duration (OR 1.031/day) were additional independent predictors.
- A cholestasis-first screening identified both confirmed and likely undiagnosed SSC-CIP cases.
Methodological Strengths
- Very large ICU cohort with multivariable adjustment and dose-response analysis
- Novel cholestasis-first screening strategy to capture undiagnosed cases
Limitations
- Single-center retrospective design limits causal inference and external validity
- Potential residual confounding by illness severity, concomitant drugs, and ICU practices
Future Directions: Prospective multicenter validation and randomized evaluations of ketamine-sparing sedation bundles in populations at risk for SSC-CIP.
BACKGROUND: Secondary sclerosing cholangitis in critically ill patients (SSC-CIP) is a severe cholangiopathy with high mortality observed in ICU survivors. While prolonged mechanical ventilation and COVID-19-associated acute respiratory distress syndrome (ARDS) are established risk factors, the impact of ketamine, a commonly used sedative, remains controversial. METHODS: This retrospective study included 20,973 ICU patients admitted between January 2014 and February 2022 at a tertiary university hospital. Patients with severe cholestasis were preselected (n = 532) and reviewed for SSC-CIP diagnosis or likelihood of SSC-CIP. Multivariate logistic regression was used to evaluate Esketamine exposure and dose dependency while controlling for other risk factors. RESULTS: SSC-CIP was confirmed in 0.11% of patients; 0.20% had clinical profiles compatible with undiagnosed SSC-CIP. Among COVID-19 ICU patients, the incidence was 3.24%. Esketamine administration was significantly associated with SSC-CIP (70% of SSC cases vs. 7% controls). In a multivariate analysis, cumulative Esketamine dose (OR 1.021 per gram), ICU duration (OR 1.031/day), and COVID-19 status (OR 20.6) were independent predictors. CONCLUSION: Esketamine exposure was associated with SSC-CIP in a dose-dependent manner, highlighting the need for judicious sedative use in critically ill patients. Our cholestasis-first screening strategy also demonstrates a novel approach for detecting previously unrecognized SSC-CIP cases. Future prospective trials should evaluate the benefits of ketamine-free sedation strategies in high-risk populations.
3. Effect of a liberal fluid fasting policy before surgery on the incidence of aspiration: a single centre retrospective observational study.
In 56,995 adults under anesthesia following implementation of a liberal clear-fluid fasting policy (median 63 minutes), recognized pulmonary aspiration occurred at 3.7 per 10,000 cases, higher than historical rates reported with 2-hour fasting. Regurgitation and aspiration pneumonia were 25 and 2.1 per 10,000, respectively.
Impact: Largest real-world assessment to date linking liberalized clear-fluid fasting with a higher observed aspiration incidence, directly informing perioperative fasting policy debates.
Clinical Implications: Reassess liberal fasting policies, especially in high-risk patients; shared decision-making should weigh patient comfort against a potentially higher aspiration risk, and consider targeted mitigation (e.g., risk stratification, airway plans).
Key Findings
- Pulmonary aspiration incidence under a liberal clear-fluid policy was 3.7 per 10,000 cases.
- Regurgitation and aspiration pneumonia incidences were 25 and 2.1 per 10,000, respectively.
- Median clear-fluid fasting time was 63 minutes, substantially shorter than traditional 2-hour guidance.
Methodological Strengths
- Very large cohort with standardized aspiration definition based on direct visualization
- Assessment of regurgitation and aspiration pneumonia with logistic regression to explore risk factors
Limitations
- Single-center retrospective design; absence of a contemporaneous 2-hour fasting control group
- Potential documentation bias and unmeasured confounding
Future Directions: Prospective, multicenter comparative studies of liberal versus standard fasting with stratification by aspiration risk and procedure type; implementation trials testing targeted mitigation strategies.
BACKGROUND: In adults undergoing anaesthetic procedures, a preoperative fasting duration of 2 h for clear fluids is advised to minimise pulmonary aspiration risk. This fasting duration is under debate, because a shorter duration has been shown to improve patient wellbeing and seems not markedly to increase the aspiration risk. Although some hospitals already have adopted such a policy, large-scale studies addressing safety of this strategy are lacking. Therefore, the primary aim of this study was to assess the incidence of aspiration after implementation of a liberal fluid fasting policy. METHODS: This observational single-centre cohort study was performed in a Dutch tertiary referral hospital after implementation of a liberal fluid fasting policy and included adults undergoing elective and urgent procedures under anaesthesia. The primary outcome was pulmonary aspiration, defined as documented visualisation of gastric content in the tracheobronchial tree below the vocal cords as seen by laryngoscopy, bronchoscopy, after tracheal suctioning with or without signs of respiratory distress or both. Secondary outcomes were regurgitation (visualisation of gastric content in the oral cavity or pharynx) or aspiration pneumonia. Risk factors for aspiration were identified using logistic regression analysis. RESULTS: Between June 2019 and February 2025, 56 995 patients were evaluated with a recognised aspiration incidence of 3.7 (95% confidence interval [CI] 2.4-5.6) per 10 000 patients. The incidence of regurgitation was 25 (95% CI 21-29) per 10 000, and aspiration pneumonia occurred in 2.1 (95% CI 1.2-3.7) per 10 000. Median fasting duration for clear fluids was 63 min (inter-quartile range 24-116 min). CONCLUSIONS: A liberal fasting policy for clear fluids before elective and urgent surgery in adults had a higher associated incidence of aspiration compared with the previously reported incidence using a standard 2-h fasting policy. Because a liberal fasting policy has been shown to improve patient wellbeing, this study could contribute to the discussion among patients and clinicians to balance the benefits and risks of such a liberal policy.