Weekly Anesthesiology Research Analysis
This week’s anesthesiology literature emphasized precision perioperative management, persistent implementation gaps in routine practice, and practical diagnostic workarounds for critical care. A machine‑learning secondary analysis of STOP-or-NOT shows heterogeneous hypotension risk with continued RAAS inhibitors and enables CATE-based individualized decisions. Large multicountry data reveal pervasive over‑fasting before anesthesia, and a systematic review provides practical SF→PF conversion equa
Summary
This week’s anesthesiology literature emphasized precision perioperative management, persistent implementation gaps in routine practice, and practical diagnostic workarounds for critical care. A machine‑learning secondary analysis of STOP-or-NOT shows heterogeneous hypotension risk with continued RAAS inhibitors and enables CATE-based individualized decisions. Large multicountry data reveal pervasive over‑fasting before anesthesia, and a systematic review provides practical SF→PF conversion equations to aid respiratory assessment when ABGs are unavailable.
Selected Articles
1. Impact of continuing renin-angiotensin-aldosterone system inhibitors before surgery on intraoperative hypotensive events: a secondary analysis of the STOP-or-NOT Trial.
Secondary analysis of the STOP‑or‑NOT RCT (n=2007) used CATE machine‑learning methods to show significant heterogeneity in intraoperative hypotension risk when RAAS inhibitors are continued before major noncardiac surgery. A high‑risk subgroup (top 20%)—younger and with higher BMI—had the largest absolute increase in hypotension requiring vasopressors, while a low‑risk subgroup had minimal impact.
Impact: Operationalizes precision perioperative medication management by quantifying who is at increased hypotension risk from continuing RAAS inhibitors, enabling selective withholding rather than blanket policies.
Clinical Implications: Incorporate HTE/CATE-informed risk stratification into preoperative medication reconciliation: consider withholding RAAS inhibitors for patients identified as high‑risk (e.g., younger, higher BMI) and continue in low‑risk patients to avoid unnecessary cardiac risk.
Key Findings
- Demonstrated significant heterogeneity of treatment effect for intraoperative hypotension with RAASi continuation across 2007 patients.
- High‑risk subgroup (top 20%) had a CATE risk difference ≈0.172 and tended to be younger with higher BMI.
- Machine‑learning CATE stratification enabled splitting patients into high/medium/low risk for individualized decisions.
2. Preoperative liquid fasting practices in twelve European countries: A prospective multicentre cohort study (Thirst study).
Prospective cohort across 46 centers and 12 countries (n=5100) found median preoperative clear‑liquid fasting was 12 hours and 95% fasted beyond 4 hours; only 0.8% drank within the guideline‑recommended 2 hours. The study quantifies a large, modifiable implementation gap with implications for patient comfort and perioperative outcomes.
Impact: Large, contemporary multicountry evidence quantifying widespread nonadherence to fasting guidelines; directly actionable for quality improvement and patient‑centered fasting protocols.
Clinical Implications: Implement protocols to permit clear liquids up to 2 hours pre‑anesthesia, audit fasting instructions and scheduling, and deploy nurse‑led hydration pathways and EHR prompts to reduce unnecessary prolonged fasting.
Key Findings
- Median preoperative clear‑liquid fasting was 12 hours [IQR 10–14.6] (n=5100).
- 95% of patients fasted longer than 4 hours; only 0.8% drank within 2 hours before anesthesia.
- Excessive fasting was consistent across countries and procedure types, highlighting implementation failure.
3. Approaches to Converting Spo2/Fio2 Ratio to Pao2/Fio2 Ratio for Assessment of Respiratory Failure in Critically Ill Patients: A Systematic Review.
Systematic review of 45 observational studies (measurement counts up to ~141,000) found strong SF–PF correlations overall but degradation of conversion accuracy when SpO2 ≥97%. Authors prioritize four practical equations (including a simple linear model) for bedside use and recommend caution at high SpO2.
Impact: Delivers immediately applicable conversion tools to estimate PaO2/FiO2 from noninvasive SpO2/FiO2 at the bedside, filling a practical gap when ABGs are delayed or unavailable in critical care and anesthesiology settings.
Clinical Implications: Adopt prioritized linear SF→PF equations in protocols and EHR calculators to approximate oxygenation severity quickly, but avoid relying on conversions when SpO2 ≥97%; prospectively validate equations for device calibration.
Key Findings
- SF→PF correlation strong across studies; conversion accuracy worsens when SpO2 ≥97%.
- No single universally superior equation, but four practical equations (one linear, one log-linear, two nonlinear) prioritized for bedside use.
- SF ratio may have prognostic value comparable to PF in certain settings.