Daily Anesthesiology Research Analysis
A randomized trial shows high-flow nasal oxygen can safely replace laryngeal mask ventilation for short general anesthesia without neuromuscular blockade, though hypercarbia requires vigilance. A mechanistic study validates the recruitment-to-inflation ratio as a bedside indicator of recruitability to personalize PEEP. A nationwide ICU registry analysis from Japan challenges Western concepts of persistent critical illness onset, suggesting health system and cultural effects.
Summary
A randomized trial shows high-flow nasal oxygen can safely replace laryngeal mask ventilation for short general anesthesia without neuromuscular blockade, though hypercarbia requires vigilance. A mechanistic study validates the recruitment-to-inflation ratio as a bedside indicator of recruitability to personalize PEEP. A nationwide ICU registry analysis from Japan challenges Western concepts of persistent critical illness onset, suggesting health system and cultural effects.
Research Themes
- Intraoperative respiratory support strategies
- Personalized ventilation and recruitability metrics
- ICU outcomes and health-system variation
Selected Articles
1. High-Flow Nasal Oxygen versus Mechanical Ventilation Through a Laryngeal Mask During General Anesthesia Without Muscle Paralysis: A Randomized Clinical Trial.
In 180 ASA I–II patients undergoing 30-minute propofol anesthesia without paralysis, high-flow nasal oxygen achieved a 99% success rate, noninferior to laryngeal mask ventilation. HFNO reduced postoperative respiratory symptoms (2% vs 19%) but increased intraoperative hypercarbia (43% with TcCO2 >55 mm Hg).
Impact: This pragmatic RCT directly informs intraoperative airway strategy in short procedures, showing HFNO can obviate supraglottic devices while improving patient-reported respiratory outcomes.
Clinical Implications: HFNO is a viable alternative to laryngeal mask ventilation for short general anesthesia without neuromuscular blockade, potentially reducing postoperative throat/airway symptoms. However, clinicians must monitor for hypercarbia and select patients carefully (e.g., avoid those with limited CO2 reserve).
Key Findings
- Primary noninferiority outcome met: 99% intraoperative support success in both HFNO and LMA groups.
- Postoperative respiratory symptoms were significantly lower with HFNO (2% vs 19%).
- HFNO led to higher intraoperative transcutaneous CO2, with 43% >55 mm Hg.
Methodological Strengths
- Randomized noninferiority design with clear, objective primary endpoint.
- Complete follow-up of all 180 randomized patients and prespecified secondary outcomes.
Limitations
- Single-center study in operative hysteroscopy with 30-minute anesthesia, limiting generalizability.
- Exclusion of neuromuscular blockade; findings may not apply to longer or more complex surgeries.
Future Directions: Multicenter trials across varied surgical populations and anesthetic durations should evaluate HFNO protocols, CO2 monitoring strategies, and thresholds for rescue ventilation.
2. Evaluation of the Potential for Lung Recruitment with the Recruitment-to-Inflation Ratio during General Anesthesia.
In a prospective physiologic study of 20 patients, the recruitment-to-inflation ratio correlated strongly with recruitable volume by electrical impedance tomography (r=0.82). Patients with R/I>0.40 benefited from higher PEEP with reduced dead space, collapse, and dynamic strain, supporting R/I as a bedside metric to individualize PEEP.
Impact: Provides a practical, equipment-free ventilator-derived index to gauge recruitability under general anesthesia, advancing personalized ventilation strategies.
Clinical Implications: Anesthesiologists can consider using a single-breath PEEP-release maneuver to calculate R/I and tailor PEEP—particularly when R/I >0.4—to minimize collapse and overdistension.
Key Findings
- R/I correlated strongly with EIT-derived recruitable volume (r=0.82) and moderately with gas-dilution metrics.
- Patients with R/I >0.40 required higher optimal PEEP (median 10 vs 8 cmH2O; P=0.03).
- Higher PEEP in high R/I patients reduced dead space (−2% vs +3%), collapse (−44% vs −30%), and dynamic lung strain (−0.06 vs −0.04).
Methodological Strengths
- Comprehensive multimodal physiology (EIT, nitrogen dilution, gas exchange, mechanics).
- Standardized protocol with within-patient comparisons across PEEP steps.
Limitations
- Small single-center sample (n=20) limits external validity.
- Short-term physiologic endpoints without clinical outcomes; open abdominal surgery only.
Future Directions: Validate R/I-guided PEEP strategies in larger, diverse surgical cohorts with clinical outcomes (oxygenation failure, postoperative pulmonary complications).
3. Timing of onset of persistent critical illness in Japan: a nationwide registry study.
Analyzing 285,567 ICU patients in Japan, the AUROC for acute illness consistently exceeded antecedent characteristics through day 28, indicating no identifiable onset of persistent critical illness. This contrasts with Western reports and implies system-level differences in ICU trajectories and end-of-life practices.
Impact: A very large, multicenter registry challenges a widely cited ICU paradigm, reframing how we conceptualize and measure transitions to persistent critical illness in different health systems.
Clinical Implications: Risk stratification tools and resource planning based on Western PerCI timing may not generalize to Japan; local validation is essential for palliative triggers, staffing, and rehabilitation pathways.
Key Findings
- In 285,567 ICU admissions, acute illness AUROC remained higher than antecedent characteristics through day 28.
- No crossover point indicating PerCI onset was observed; overall in-hospital mortality was 8.2%.
- Findings suggest health-system and cultural factors may influence ICU trajectories and PerCI definitions.
Methodological Strengths
- Nationwide, multicenter registry with very large sample size and predefined AUROC-based framework.
- Robust multivariable logistic models assessed daily from ICU day 1 to day 28.
Limitations
- Observational design cannot establish causality; unmeasured confounding may persist.
- Findings may be specific to Japan’s ICU practices; external validation is needed.
Future Directions: Cross-national comparative analyses using harmonized methods could clarify how end-of-life policies, rehabilitation timing, and ICU discharge practices shape PerCI onset.