Daily ReportSep 20, 2026
Anesthesiology, September 20 edition
We read 5 papers and selected 3.
Summary
Today's most impactful studies span mechanistic anesthetic neurobiology, airway safety during pediatric induction, and perioperative neurologic diagnosis. The strongest evidence comes from a prospective randomized trial showing that apneic oxygenation prevents intubation-associated desaturation in children, while a sophisticated mouse study provides a circuit-level explanation for S-ketamine-induced hallucination-like behavior.
Research Themes
- Circuit mechanisms of anesthetic-induced perceptual and behavioral disruption
- Prevention of peri-intubation hypoxemia in children
- Recognition and differential diagnosis of perioperative neurologic deficits
Selected Articles
1. A circuit dissection of perception-action decoupling in S-ketamine-induced hallucination-like states.
This multimodal mouse study separated perceptual false alarms from disorganized behavioral expression during S-ketamine exposure. The basolateral amygdala-to-caudal striatum pathway promoted salience-weighted false auditory threat responses, whereas the medial prefrontal cortex-to-caudal striatum pathway shaped disorganized actions. Dexmedetomidine restored pathway-level temporal dynamics and reorganized striatal network coupling without merely suppressing neuronal activity.
Impact: The study provides a mechanistic framework for dissociating perception from behavioral output in an anesthetic-related hallucination model. Its pathway-specific findings also offer a biologically grounded rationale for investigating dexmedetomidine as a strategy to mitigate ketamine-associated perceptual and behavioral disruption.
Clinical Implications: The findings support further translational studies of dexmedetomidine for managing ketamine-related hallucination-like or behavioral disturbances, particularly in anesthetic and procedural settings. Direct clinical application remains premature because the evidence derives from mice and an experimental S-ketamine paradigm.
Key Findings
- The basolateral amygdala-to-caudal striatum pathway promoted S-ketamine-induced false auditory threat responses.
- The medial prefrontal cortex-to-caudal striatum pathway primarily generated disorganized action patterns.
- Dexmedetomidine restored striatal pathway timing and network coupling without simply suppressing overall activity.
Methodological Strengths
- Integrated behavioral analysis, AI-based pose tracking, fiber photometry, single-cell calcium imaging, and pathway-specific causal manipulations.
- Used bidirectional chemogenetic manipulation and dexmedetomidine intervention to test circuit causality and reversibility.
Limitations
- The study used a mouse model, so the relationship to human hallucinations and perioperative symptoms remains uncertain.
- The abstract does not provide the number of animals, and the experimental S-ketamine paradigm may not capture the full clinical variability of ketamine exposure.
Future Directions: Future work should validate these pathway mechanisms in human neuroimaging or translational models, define dose- and state-dependent effects of dexmedetomidine, and test whether the circuit signatures predict emergence delirium or ketamine-related perceptual disturbances.
Hallucinations are a core feature of several psychiatric disorders, but the circuit mechanisms that separate perception from behavioral output remain poorly defined. Here, we combined an auditory discrimination task with AI-based pose analysis to quantify S-ketamine-induced false auditory threat responses and behavioral disorganization in mice. Control assays, including sucrose preference, loss of righting reflex, and prepulse inhibition, indicated that these effects were not explained by anhedonia, anesthesia, or basic auditory deficits. Using in vivo fiber photometry, single-cell miniscope calcium imaging, and pathway-specific chemogenetic and optogenetic manipulations, we identified dissociable circuit contributions within convergent striatal pathways.
2. Effectiveness of Apneic Oxygenation During Induction of General Anesthesia in Children Undergoing Adenotonsillectomy: A Prospective Randomized Controlled Study.
In 140 children undergoing adenotonsillectomy, nasal apneic oxygenation at 0.2 L/kg/min significantly improved the lowest peripheral oxygen saturation during intubation compared with standard care. No child in the apneic oxygenation group desaturated, whereas 21.43% of controls reached 95% or lower and 7.14% reached below 92%. Intubation time, attempts, and bradycardia rates were similar between groups.
Impact: This randomized trial addresses a common and clinically important airway-safety problem in a high-risk pediatric population. The large absolute reduction in clinically relevant desaturation supports apneic oxygenation as a simple, low-complexity intervention worthy of broader evaluation and protocol consideration.
Clinical Implications: During pediatric adenotonsillectomy induction, nasal apneic oxygenation may reduce peri-intubation hypoxemia without prolonging intubation or increasing bradycardia. Clinicians should still individualize flow rates, monitor for gastric insufflation and airway obstruction, and confirm these findings in broader pediatric populations and different airway-management protocols.
Key Findings
- Lowest SpO2 during intubation was higher with apneic oxygenation than with standard intubation: 99.91% versus 97.40%, P < 0.001.
- No apneic oxygenation participant desaturated, compared with 21.43% of controls reaching SpO2 of 95% or lower.
- Severe desaturation below 92% occurred in 7.14% of controls and in none of the apneic oxygenation participants, without differences in intubation efficiency or bradycardia.
Methodological Strengths
- Prospective randomized controlled design with a clearly defined primary oxygenation outcome.
- Balanced groups of 70 children each and assessment of both efficacy and procedural safety outcomes.
Limitations
- The study was single-blinded and conducted in children undergoing a specific adenotonsillectomy procedure, which may limit generalizability.
- The abstract does not describe allocation concealment, protocol registration, or longer-term postoperative respiratory outcomes.
Future Directions: Larger multicenter trials should evaluate apneic oxygenation across diverse pediatric airway procedures, compare different oxygen flow rates and interfaces, and assess adverse effects such as gastric insufflation, hyperoxia, and postoperative respiratory complications.
BACKGROUND: Children undergoing adenotonsillectomy often have partial airway obstruction due to hypertrophic tonsils and adenoids, increasing their risk of oxygen desaturation during anesthesia induction. OBJECTIVES: This study aimed to evaluate whether apneic oxygenation via nasal cannula prevents oxygen desaturation during tracheal intubation in children aged 3 - 10 years undergoing adenotonsillectomy while assessing its effects on intubation conditions and hemodynamic stability. METHODS: In this prospective, single-blinded, randomized controlled trial, 140 children scheduled for adenotonsillectomy were allocated to either standard intubation (group A, n = 70) or apneic oxygenation (group B, n = 70; 0.2 L/kg/min via nasal cannula).
3. Post-Stroke Recrudescence During the Perioperative Period: Potential Roles of Anesthetic and Sedative Agents.
This narrative review synthesizes the perioperative diagnostic problem of post-stroke recrudescence, in which prior focal deficits transiently reappear without a new infarct. Human evidence is strongest for midazolam and benzodiazepines, whereas evidence for opioids, propofol, volatile anesthetics, and dexmedetomidine is limited or indirect. The review emphasizes that recrudescence is a diagnosis of exclusion and must not delay urgent evaluation for acute stroke.
Impact: The review addresses a high-stakes perioperative diagnostic dilemma that can lead either to missed acute stroke or unnecessary alarm. Its careful separation of medication-associated evidence from concurrent surgical stressors provides a clinically useful framework while explicitly identifying the lack of causal prospective data.
Clinical Implications: Clinicians should document preoperative neurologic deficits, compare postoperative findings with the prior stroke pattern, correct systemic triggers, and involve neurology early. Suspected post-stroke recrudescence should never substitute for prompt stroke evaluation or diffusion-weighted brain imaging when clinically indicated.
Key Findings
- Post-stroke recrudescence reproduces prior stroke deficits transiently without a new diffusion-weighted imaging lesion.
- Human evidence implicates midazolam and benzodiazepines more strongly than opioids, propofol, volatile anesthetics, or dexmedetomidine.
- Hypotension, hypoxemia, infection, electrolyte abnormalities, pain, and sleep disruption complicate attribution to any single anesthetic or sedative agent.
Methodological Strengths
- Clearly distinguishes post-stroke recrudescence from acute ischemic stroke, residual anesthesia, seizure, and delirium.
- Appropriately grades the evidence for individual anesthetic and sedative classes and highlights confounding perioperative stressors.
Limitations
- As a narrative review, the search strategy, study selection process, and risk-of-bias assessment may not be reproducible or comprehensive.
- The underlying human literature is limited, heterogeneous, and largely unable to establish independent causal effects of specific medications.
Future Directions: Prospective perioperative registries should record specific agents, doses, timing, hemodynamic and respiratory stressors, imaging findings, baseline neurologic status, and outcomes. Standardized diagnostic criteria and multicenter studies are needed to quantify medication-specific risk and distinguish recrudescence from new stroke.
Post-stroke recrudescence (PSR) is the transient reappearance of previously recovered focal neurologic deficits after a systemic or pharmacologic stressor, without evidence of a new cerebral infarction. In the perioperative setting, PSR can closely resemble acute ischemic stroke, residual anesthetic effects, seizure, or delirium, creating a significant diagnostic challenge. This narrative review examines the proposed mechanisms of PSR and evaluates the available evidence regarding anesthetic, sedative, and analgesic agents as potential triggers. Previously injured neural networks may remain vulnerable to disruptions in excitatory-inhibitory balance despite apparent clinical recovery. Human evidence is strongest for midazolam and broader benzodiazepine exposure, while evidence involving opioids, propofol, volatile anesthetics, and dexmedetomidine remains limited or indirect.