Weekly Anesthesiology Research Analysis
This week’s anesthesiology literature emphasized pragmatic perioperative strategies and translational mechanisms. High-quality syntheses clarified transfusion thresholds and steroid dosing in critical care, a large multicenter RCT (PHOENICS) resolved safety concerns about in‑label 6% HES in major surgery, and a mechanistic preclinical study identified microglia-mediated perineuronal net loss as a pathway linking neonatal sevoflurane to social memory deficits. Together these studies affect fluid
Summary
This week’s anesthesiology literature emphasized pragmatic perioperative strategies and translational mechanisms. High-quality syntheses clarified transfusion thresholds and steroid dosing in critical care, a large multicenter RCT (PHOENICS) resolved safety concerns about in‑label 6% HES in major surgery, and a mechanistic preclinical study identified microglia-mediated perineuronal net loss as a pathway linking neonatal sevoflurane to social memory deficits. Together these studies affect fluid and transfusion stewardship, perioperative neuroprotection research priorities, and reinforce targeted individualized care pathways.
Selected Articles
1. Transfusion thresholds and other strategies for guiding red blood cell transfusion.
A Cochrane review of 61 trials (27,639 participants) found that restrictive transfusion thresholds (Hb ≈7–8 g/dL) reduced red cell exposure by ~42% without increasing 30‑day mortality overall. Subgroup analyses revealed context-specific effects: restrictive strategies were favorable in GI bleeding, whereas liberal strategies improved longer‑term neurologic outcomes in neurocritical patients. Transfusion reactions were less frequent with restrictive approaches.
Impact: This high-quality synthesis consolidates definitive evidence to guide transfusion stewardship across perioperative and critical care settings, clarifying where restrictive policies are safe and where context-specific liberal thresholds remain warranted.
Clinical Implications: Adopt restrictive transfusion thresholds (Hb ~7–8 g/dL) for most adult perioperative patients to minimize exposure and reactions, while individualizing thresholds in neurocritical care and some bleeding contexts; integrate physiologic triggers where appropriate.
Key Findings
- Restrictive strategy reduced receipt of ≥1 RBC unit by 42% across 61 trials (RR 0.58).
- No overall difference in 30‑day mortality between restrictive and liberal thresholds.
- Contextual exceptions: benefit for restrictive in GI bleeding; potential advantage for liberal strategy on longer‑term neurologic outcomes in neurocritical patients.
2. Safety and efficacy of 6% hydroxyethyl starch in patients undergoing major surgery: The randomised controlled PHOENICS trial.
PHOENICS, a multicenter double‑blind RCT (n=1,985), demonstrated that in‑label perioperative use of 6% HES 130/0.4 was noninferior to crystalloids regarding short‑term cystatin C–based eGFR decline and a 90‑day composite of mortality and major complications. No clinically relevant differences in 90‑day renal function or 1‑year mortality were observed, supporting safe, protocolized HES use in major abdominal surgery.
Impact: Addresses a long‑standing controversy with a rigorous, large, double‑blind RCT, providing actionable evidence to inform perioperative fluid choices and institutional fluid stewardship policies.
Clinical Implications: Within labeled dosing and protocolized monitoring, 6% HES 130/0.4 can be considered as an alternative to crystalloids for volume therapy in major abdominal surgery; institutions should update fluid stewardship and patient selection criteria accordingly.
Key Findings
- eGFR decline noninferior for HES vs crystalloids over first 3 postoperative days.
- Composite 90‑day mortality/major complications identical between groups (35%).
- No clinically relevant differences in safety endpoints including 90‑day renal function and 1‑year mortality.
3. Microglia-mediated Perineuronal nets loss contributes to social memory deficit in male mice after repeated neonatal sevoflurane exposure.
A mechanistic preclinical study found that repeated neonatal sevoflurane exposure (P7–9) in male mice caused social memory deficits by P28, coupled with prefrontal perineuronal net (PNN) loss, PV interneuron hyperexcitability, and increased inhibitory input to pyramidal cells. Microglia showed elevated phagocytosis of PNNs, and depletion/repopulation via PLX5622 rescued PNN integrity and social memory, demonstrating a causal microglia–PNN pathway.
Impact: Provides a cellularly resolved, causal mechanism linking early anesthetic exposure to neurodevelopmental deficits, identifying microglial activity and PNN preservation as potential intervention targets and informing safety science in pediatric anesthesia.
Clinical Implications: Although preclinical, findings justify cautious minimization of unnecessary neonatal exposures, motivate biomarker and neurodevelopmental follow‑up strategies, and prioritize translational work on microglial modulators or PNN-stabilizing agents before clinical application.
Key Findings
- Repeated neonatal sevoflurane (P7–9) produced social memory deficits in male mice by P28.
- Loss of prefrontal perineuronal nets with PV interneuron hyperexcitability and increased inhibitory input to pyramidal neurons.
- Microglial phagocytosis of PNNs increased; PLX5622-mediated microglial depletion and repopulation rescued PNNs and behavior.