Daily Anesthesiology Research Analysis
Three studies stand out in anesthesiology and critical care: a large causal-inference analysis links median mechanical power to worse ventilator-free days and rejects universal thresholds; a pragmatic, registered before–after study shows that simply removing desflurane vaporizers plus staff education rapidly and substantially cuts anesthesia-related greenhouse emissions; and a 5,025-patient cardiac ICU analysis finds central/mixed venous oxygen saturation and lactate are weakly related to hemogl
Summary
Three studies stand out in anesthesiology and critical care: a large causal-inference analysis links median mechanical power to worse ventilator-free days and rejects universal thresholds; a pragmatic, registered before–after study shows that simply removing desflurane vaporizers plus staff education rapidly and substantially cuts anesthesia-related greenhouse emissions; and a 5,025-patient cardiac ICU analysis finds central/mixed venous oxygen saturation and lactate are weakly related to hemoglobin and minimally responsive to transfusion, challenging physiologic transfusion triggers.
Research Themes
- Personalized mechanical ventilation and causal inference
- Sustainable anesthesia and greenhouse gas reduction
- Transfusion decision-making in cardiac anesthesia/ICU
Selected Articles
1. Elucidating the causal relationship of mechanical power and lung injury: a dynamic approach to ventilator management.
Across 11,110 ICU admissions, median mechanical power had a significant negative causal effect on ventilator-free days at day 28, whereas maximal/minimal MP did not. Effects were stronger in medical patients, and simulations demonstrated no universal MP threshold, supporting individualized MP targets.
Impact: Defines a causal, patient-specific relationship between ventilator energy load and clinical outcomes, challenging threshold-based protocols and advancing personalized ventilation strategies.
Clinical Implications: Prioritize minimizing median mechanical power and avoid one-size-fits-all thresholds; adjust MP dynamically to patient condition (especially in medical ICU cohorts) to improve ventilator-free days.
Key Findings
- Median mechanical power showed a significant negative causal effect on VFD28 (ATE −0.135; 95% CI −0.15 to −0.121).
- No similar causal effect was observed for maximal or minimal mechanical power.
- Effects were stronger in medical patients (CATE −0.173; 95% CI −0.197 to −0.143), and simulations indicated no universal MP threshold.
Methodological Strengths
- Large real-world ICU cohort (n=11,110) with causal inference methods (ATE/CATE, backdoor regression).
- Simulation analyses to test threshold generalizability across conditions.
Limitations
- Retrospective database design with potential residual confounding.
- Single database; external generalizability and bedside implementation require prospective validation.
Future Directions: Prospective interventional trials that titrate mechanical power to individualized targets and assess patient-centered outcomes; development of bedside tools integrating MP with lung mechanics and disease trajectory.
BACKGROUND: Mechanical power (MP) serves as a crucial predictive indicator for ventilator-induced lung injury and plays a pivotal role in tailoring the management of mechanical ventilation. However, its application across different diseases and stages remains nuanced. METHODS: Using AmsterdamUMCdb, we conducted a retrospective study to analyze the causal relationship between MP and outcomes of invasive mechanical ventilation, specifically SpO RESULTS: In the study, we included 11,110 unique admissions into analysis, of which 58.3% (6391) were surgical admissions. We revealed a negative and significant causal effect of median MP on VFD28, with estimated ATEs of -0.135 (95% confidence interval [CI]: -0.15 to -0.121). The similar effect was not observed in Maximal MP and minimal MP. The effect of MP was more pronounced in the medical subgroup, with a CATE of -0.173 (95% CI: -0.197 to -0.143) determined through backdoor linear regression. Patients with cardio, respiratory, and infection diagnoses, who required long-term intubation, sustained higher impact on CATEs across various admission diagnoses. Our simulations showed that there is no single MP threshold that can be applied to all patients, as the optimal threshold varies depending on the patient's condition. CONCLUSION: Our study underscores the importance of tailoring MP adjustments on an individualized basis in ventilator management. This approach opens up new avenues for personalized treatment strategies and provides fresh insights into the real-time impact of MP in diverse clinical scenarios. It highlights the significance of median MP while acknowledging the absence of universally applicable thresholds.
2. Minimising the usage of desflurane only by education and removal of the vaporisers - a before-and-after-trial.
At a large German teaching hospital, removing desflurane vaporizers and educating staff enabled a rapid, significant reduction of anesthesia-related greenhouse emissions without formal restrictions and likely reduced costs.
Impact: Provides a simple, scalable, systems-level intervention to decarbonize anesthesia practice with immediate environmental and financial benefits.
Clinical Implications: Hospitals can phase out desflurane by physically removing vaporizers and delivering targeted education, shifting to lower-GWP alternatives and total intravenous anesthesia where appropriate.
Key Findings
- A before–after intervention (vaporizer removal plus staff education) achieved rapid, significant reductions in anesthesia-related greenhouse gas emissions.
- The approach did not rely on formal usage restrictions and may also reduce costs.
- Trial was prospectively registered (DRKS00024973), supporting transparency and replicability.
Methodological Strengths
- Prospective before–after design at an entire hospital service with 12-month observation.
- Pragmatic, simple intervention with clear systems-level relevance; trial registration.
Limitations
- Nonrandomized single-center design susceptible to secular trends and co-interventions.
- Abstract does not report detailed quantitative CO2e metrics in this excerpt.
Future Directions: Multicenter implementation with full quantitative GHG accounting and cost analyses; behavioral nudges and dashboards to sustain low-emission practices; evaluation of patient outcomes and workflow effects.
BACKGROUND: By exceeding planetary environmental boundaries, multiple global crises have become imminent in the 21st century. The healthcare system is a contributor to the climate crisis, accounting for approximately 5% of greenhouse gas emissions in Western countries. In anaesthetic clinics, desflurane, a highly potent greenhouse gas and volatile anaesthetic with no compelling indications, accounts for up to two thirds of total emissions. Its use can be drastically reduced using simple measures. In the present study, we investigated whether a relevant and timely reduction in use could be achieved by dismounting desflurane vaporisers and providing information to the team without restricting its use. METHODS: The study was conducted in a German university hospital with approximately 1250 beds, over a 12-month period between 2021 and 2022, with a comparison to the corresponding periods of the previous years up to 2017. The interventions were, first, the removal of desflurane vaporisers, and second, staff education on the climate impact of volatile anaesthetics. The primary outcome variable was the reduction of hypnotic-related emissions in CO RESULTS: Prospective data collection and interventions were conducted from 28 March 2021 to 27 March 2022. The amount of CO CONCLUSIONS: Removal of desflurane vaporisers and staff training can quickly and significantly reduce the emissions of an anaesthesia department in a large German teaching hospital. This may also reduce the costs. TRIAL REGISTRATION: The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021.
3. Central/mixed venous oxygen saturation and lactate levels might be of limited use as physiologic transfusion triggers in cardiac surgery: Results of a retrospective analysis.
In 5,025 cardiac surgery ICU patients, hemoglobin had only weak correlations with SvO2 and lactate, and changes in SvO2 or lactate after pRBC transfusion did not correlate with pretransfusion hemoglobin. These data challenge using SvO2 and lactate as physiologic transfusion triggers.
Impact: Large-scale evidence questions widely discussed physiologic triggers, with direct implications for transfusion protocols in cardiac anesthesia and ICU care.
Clinical Implications: Avoid relying on SvO2 and lactate as stand-alone physiologic triggers for transfusion in cardiac surgery ICU; integrate broader clinical context and validated thresholds/algorithms.
Key Findings
- Among 5,025 patients (20,542 blood gases), Hb–SvO2 correlation was statistically significant but weak (r2=0.026).
- Hb–lactate correlation was also statistically significant but negligible (r2=0.001).
- Changes in SvO2 and lactate after pRBC transfusion did not correlate with pretransfusion Hb (r2≈0.002–0.003).
Methodological Strengths
- Very large single-center dataset with >20,000 blood gas analyses enabling precise correlation estimates.
- Clear, clinically relevant endpoints and transparent statistical reporting (r, r2, P values).
Limitations
- Retrospective, single-center design; correlation analyses cannot establish causality.
- Physiologic responses may depend on timing and concurrent therapies not fully captured.
Future Directions: Prospective, protocolized studies testing transfusion decision algorithms that de-emphasize SvO2/lactate as triggers and validate alternative composite criteria.
BACKGROUND: Current guidelines differ in their recommendations regarding the use of physiologic transfusion triggers to guide transfusion practice. Data on the interaction between haemoglobin (Hb) and physiologic transfusion triggers, or their response to packed red blood cell (pRBC) transfusions are limited. OBJECTIVES: This study aimed to evaluate the interactions between Hb, mixed/central venous oxygen saturation (SvO 2 ) and lactate levels as well as their changes (ΔSvO 2 , Δlactate) in response to pRBC transfusion in cardiac surgery patients. DESIGN: Retrospective exploratory data analysis. SETTING: A 22-bed intensive care unit (ICU) at a single tertiary academic centre and university hospital in Austria. PATIENTS: Adult (age ≥ 18 years) patients who underwent cardiac surgery. MAIN OUTCOME MEASURES: Pearson correlation coefficients ( r ) and coefficients of determination ( r2 ) between Hb, mixed/central venous oxygen saturation (SvO 2 ), and lactate levels. Pearson correlation coefficients ( r ) and coefficients of determination ( r2 ) between ΔSvO 2 , Δlactate and pretransfusion Hb. RESULTS: A total of 5025 cardiac surgery patients, in whom 20 542 blood gas analyses were performed, were included in the final analysis. Correlations between Hb levels and SvO 2 ( r2 = 0.026, P < 0.001) and between Hb and lactate levels ( r2 = 0.001, P < 0.001) were statistically significant but weak overall. No correlations were found between ΔSvO 2 ( r2 = 0.002, P = 0.13) or Δlactate ( r2 = 0.003, P = 0.087) and pretransfusion Hb levels. CONCLUSIONS: Hb, SvO 2 and lactate levels were only weakly correlated with each other, and changes in SvO 2 and lactate levels in response to pRBC transfusion did not correlate with pretransfusion Hb. Our findings question the usefulness of SvO 2 and lactate levels as physiologic transfusion triggers to guide transfusion practice in cardiac surgery patients. TRIAL REGISTRATION: Johannes Kepler University Ethics Committee Study Reference Number 1063/2023.