Anesthesiology, September 10 edition

In 185,455 adults undergoing noncardiac surgery, in-hospital mortality was 0.85%. Lower intraoperative ETCO₂ showed a nonlinear association with mortality, with an adjusted odds ratio of 1.63 for every 5-mmHg decrease from the median, independent of minute ventilation and intraoperative hypotension.

Impact: This is a very large perioperative cohort demonstrating that ETCO₂ may capture clinically important risk information not explained by blood pressure or ventilation alone. The finding could support development of intraoperative warning systems and postoperative risk stratification, although causality is not established.

Clinical Implications: Persistently low intraoperative ETCO₂ should prompt assessment of ventilation, cardiac output, perfusion, pulmonary vascular status, anesthetic depth, and surgical factors rather than being interpreted solely as a ventilation target. ETCO₂ may become an additional component of perioperative risk surveillance, but intervention thresholds require prospective validation.

Future Directions: Prospective multicenter studies should determine whether ETCO₂-guided interventions improve outcomes and should evaluate causal pathways linking low ETCO₂ to mortality. Dynamic thresholds incorporating patient characteristics, surgical context, cardiac output, and perfusion markers may be more useful than a single universal cutoff.

This single-blind randomized trial included 100 adults undergoing tubeless microlaryngoscopic vocal fold polyp surgery. Adding jet ventilation to THRIVE produced a markedly smaller increase in transcutaneous carbon dioxide than THRIVE alone without increasing perioperative adverse events.

Impact: The study addresses a central limitation of tubeless airway anesthesia: oxygenation can be maintained while carbon dioxide clearance remains inadequate. A simple combined ventilation strategy may expand the safety margin for selected microlaryngoscopic procedures.

Clinical Implications: For selected tubeless microlaryngoscopic procedures, THRIVE combined with jet ventilation may reduce hypercapnia while preserving an unobstructed surgical field. Implementation requires experienced airway teams, continuous carbon dioxide monitoring, careful attention to barotrauma risk, and patient-specific selection.

Future Directions: Larger multicenter trials should evaluate procedure duration, arterial blood gas outcomes, airway pressure, barotrauma, postoperative recovery, and patient-centered outcomes. Studies should also define the optimal jet ventilation settings and identify procedures and patients most likely to benefit.

In 200 patients requiring general anesthesia, preoxygenation with 80% inspired oxygen achieved the target-based preoxygenation endpoint in a median of 95 seconds versus 99.5 seconds with 100% oxygen. The reported results supported non-inferiority of 80% oxygen for time to adequate preoxygenation, suggesting that routine use of 100% oxygen may not be necessary for every patient.

Impact: This pragmatic randomized study tests a low-cost strategy that could reduce absorption atelectasis and unnecessary oxygen exposure without delaying adequate preoxygenation. The finding is particularly relevant to routine general anesthesia, although safety in patients with limited pulmonary reserve requires further study.

Clinical Implications: An 80% oxygen strategy may be considered for preoxygenation in appropriately selected patients when target end-tidal oxygen monitoring is available. Clinicians should individualize the approach for patients with hypoxemia, difficult airway, reduced functional residual capacity, pregnancy, or anticipated prolonged apnea.

Future Directions: Future trials should include high-risk populations and evaluate absorption atelectasis, arterial oxygenation, postoperative pulmonary complications, and patient-centered recovery outcomes. Protocols should define when 80% oxygen is insufficient and whether target-based titration can reduce oxygen exposure safely across different preoxygenation devices.