Daily Anesthesiology Research Analysis
Three studies stand out today in anesthesiology: a global analysis shows a 27% reduction in greenhouse gas impact from volatile anesthetics driven by desflurane declines; high-precision LC/MS pharmacokinetics reveal intranasal oxytocin has extremely low bioavailability (~0.7%), with a public dosing simulator provided; and a prospective cardiac surgery cohort identifies actionable renal NIRS rSO2 thresholds predicting acute kidney injury.
Summary
Three studies stand out today in anesthesiology: a global analysis shows a 27% reduction in greenhouse gas impact from volatile anesthetics driven by desflurane declines; high-precision LC/MS pharmacokinetics reveal intranasal oxytocin has extremely low bioavailability (~0.7%), with a public dosing simulator provided; and a prospective cardiac surgery cohort identifies actionable renal NIRS rSO2 thresholds predicting acute kidney injury.
Research Themes
- Sustainable anesthesia and climate action
- Translational perioperative pharmacology and dosing
- Perioperative organ protection and monitoring
Selected Articles
1. Plasma pharmacokinetics of intravenous and intranasal oxytocin in nonpregnant adults.
Using LC/MS, the authors showed that intravenous oxytocin follows a robust two-compartment model, whereas intranasal oxytocin has very low bioavailability (~0.7%) and high intersubject variability. LC/MS concentrations exceeded ELISA, and a public simulator was released to inform dosing in future studies.
Impact: This work resolves long-standing uncertainty around intranasal oxytocin by providing specific, LC/MS-based PK and an open simulator, likely redirecting clinical and translational research. It challenges assumptions about intranasal efficacy and supports more reliable dosing strategies.
Clinical Implications: Intranasal oxytocin is unlikely to achieve therapeutic systemic levels; trials and clinical use should reconsider this route or adjust expectations. Intravenous dosing can be modeled more reliably, and the simulator can guide future dosing strategies.
Key Findings
- Intravenous oxytocin PK is well described by a two-compartment model (0% bias; 18% median inaccuracy).
- Intranasal oxytocin shows very low bioavailability (~0.7%) with substantial intersubject variability (47% median inaccuracy).
- LC/MS yields systematically higher oxytocin concentrations than ELISA in simultaneous samples.
- A publicly available dosing simulator was created to inform future oxytocin studies.
Methodological Strengths
- Sensitive and specific LC/MS assay with NONMEM population PK modeling
- Registered prospective studies with dual-assay comparison (LC/MS vs ELISA)
Limitations
- Small sample size of healthy, nonpregnant adults limits generalizability
- Intranasal PK characterized by high variability; mechanism of low absorption not fully elucidated
Future Directions: Define mechanistic barriers to nasal absorption, evaluate alternative delivery systems or dosing strategies, and test PK–PD links in target populations with the simulator.
2. Greenhouse gas impact from medical emissions of halogenated anaesthetic agents: a sales-based estimate.
Using global sales data (2014–2023) from 91 countries, the authors estimate a 27% reduction in carbon dioxide–equivalent impact from halogenated anesthetics, driven largely by decreased desflurane use in high-income countries. The work highlights rising desflurane use in some middle-income settings and identifies replacement with sevoflurane as a major mitigation lever.
Impact: Provides the first comprehensive, global, longitudinal estimate of climate impact from anesthetic volatiles, directly informing policy, procurement, and clinical practice changes toward low-impact agents.
Clinical Implications: Supports eliminating desflurane formularies, favoring sevoflurane or TIVA where feasible, adopting low-flow anesthesia, and targeting education and policy in middle-income regions to curb rising desflurane use.
Key Findings
- Global greenhouse gas impact from halogenated anesthetics fell by 27% over 2014–2023.
- Decreased desflurane use in high-income countries largely drove the decline.
- Some middle-income countries showed increased desflurane use, suggesting targeted mitigation needs.
- Replacing desflurane/isoflurane with sevoflurane could markedly reduce climate impact.
Methodological Strengths
- Large, multinational dataset covering 80% of the global population
- Consistent 10-year time series with standardized conversion to CO2-equivalents
Limitations
- Sales data are proxies for use and may not perfectly reflect actual emissions
- Coverage excludes some countries; assumptions in conversion factors may introduce uncertainty
Future Directions: Link sales/use to measured waste gas emissions, expand coverage to 100% of countries, and evaluate impacts of low-flow protocols and alternative techniques (e.g., TIVA) on real-world emissions.
3. Intraoperative Renal Near-Infrared Spectroscopy Monitoring as a Predictor of Renal Outcomes in Cardiac Surgery.
In a prospective cohort of 357 CPB patients, intraoperative renal rSO2 time below 80%, 70%, and 60% thresholds strongly predicted postoperative AKI. Notably, >30 minutes with rSO2 <60% yielded 96.5% specificity and 86.4% sensitivity, suggesting actionable thresholds for intraoperative management.
Impact: Provides practical intraoperative thresholds for renal rSO2 that stratify AKI risk with high diagnostic performance, enabling targeted hemodynamic and renal-protective interventions.
Clinical Implications: Consider continuous renal NIRS in high-risk cardiac surgery; avoid >30 min with rSO2 <60% through fluid optimization, vasopressor support, and perfusion management; prioritize postoperative surveillance in patients breaching thresholds.
Key Findings
- Postoperative AKI occurred in 12.3% (44/357) of CPB patients and was associated with older age, longer surgery/CPB/cross-clamp times, and greater transfusion/IABP use.
- Time with renal rSO2 below 80%, 70%, and 60% robustly predicted AKI; >30 minutes below 60% predicted AKI with 96.5% specificity and 86.4% sensitivity.
- AKI patients had significantly longer ICU stays, underscoring clinical impact.
Methodological Strengths
- Prospective design with continuous intraoperative rSO2 monitoring and KDIGO-defined AKI
- ROC analysis with clear, actionable thresholds demonstrating high specificity and sensitivity
Limitations
- Single-center, observational design limits causal inference and generalizability
- No randomized intervention testing whether threshold-guided management reduces AKI
Future Directions: Multicenter validation and randomized trials testing threshold-guided hemodynamic/renal-protective strategies to reduce AKI incidence.