Daily Anesthesiology Research Analysis
Today’s most impactful anesthesiology-adjacent research spans mechanistic insight into post–ICU sequelae, large-scale practice variation in intraoperative monitoring, and pragmatic health economics in ICU rehabilitation. A translational study implicates impaired Apelin–APJ signaling in post–intensive care syndrome; registry data show hospital-driven variability in pulmonary arterial catheter use during cardiac surgery; and a trial-based economic evaluation finds early in-bed cycling is unlikely
Summary
Today’s most impactful anesthesiology-adjacent research spans mechanistic insight into post–ICU sequelae, large-scale practice variation in intraoperative monitoring, and pragmatic health economics in ICU rehabilitation. A translational study implicates impaired Apelin–APJ signaling in post–intensive care syndrome; registry data show hospital-driven variability in pulmonary arterial catheter use during cardiac surgery; and a trial-based economic evaluation finds early in-bed cycling is unlikely to be cost-effective over 90 days.
Research Themes
- Translational mechanisms of post-ICU morbidity (Apelin–APJ signaling)
- Practice variation and monitoring in cardiac anesthesia (pulmonary arterial catheter use)
- Health economics of ICU rehabilitation (in-bed cycling cost-effectiveness)
Selected Articles
1. Protective Role of Apelin in a Mouse Model of Post-Intensive Care Syndrome.
In a murine model combining lung injury and immobilization, impaired Apelin–APJ signaling drove multisystem PICS-like phenotypes that were reversed by muscle-specific Apelin overexpression and worsened by Apelin deficiency. Human ARDS survivors with ICU-acquired weakness had lower plasma Apelin, higher IL-6, and PBMC transcriptomic signatures paralleling murine neuroinflammatory programs.
Impact: This study provides a mechanistic and translational link between Apelin signaling and PICS, integrating in vivo models, single-cell transcriptomics, and human biomarker/transcriptomic data to nominate a modifiable pathway.
Clinical Implications: Apelin could serve as a biomarker and therapeutic target for ICU survivors at risk of PICS. Measuring plasma Apelin/IL-6 and developing tissue-specific modulators of Apelin–APJ signaling may enable risk stratification and intervention trials.
Key Findings
- A combined acute lung injury plus immobilization mouse model recapitulated PICS-like muscle atrophy, lung inflammation, and neurobehavioral deficits.
- Brain single-cell RNA-seq showed upregulated Alzheimer’s disease, depression, and neuroinflammation programs in endothelial cells and microglia.
- Skeletal muscle Apelin–APJ signaling was downregulated; Apelin deficiency worsened, and muscle-specific Apelin overexpression attenuated PICS-like changes and reduced systemic IL-6.
- In ARDS survivors with severe COVID-19, ICU-acquired weakness was associated with lower plasma Apelin, higher IL-6, and PBMC signatures linked to depression/neurodegeneration.
Methodological Strengths
- Multi-system, cross-species approach integrating murine models, single-cell transcriptomics, and human biomarker/transcriptomic data
- Genetic and tissue-specific modulation (Apelin deficiency and muscle-specific overexpression) with convergent phenotypic and cytokine readouts
Limitations
- Animal model generalizability to human PICS is uncertain; causality in humans remains unproven
- Tissue-specific contributions beyond skeletal muscle require clarification; sample sizes for human cohorts not specified in abstract
Future Directions: Prospective human studies to validate Apelin as a predictive biomarker and interventional trials testing Apelin–APJ pathway modulators (e.g., agonists or gene therapy) with organ-specific targeting.
Post-Intensive Care Syndrome (PICS) is a serious condition involving physical weakness, depression, and cognitive impairment that develop during or after an intensive care unit (ICU) stay, often resulting in long-term declines in quality of life. Patients with acute respiratory distress syndrome (ARDS) and severe COVID-19 are at particularly high risk, yet the molecular mechanisms underlying PICS remain poorly understood. Here, we identify impaired Apelin-APJ signaling as a potential contributor to PICS pathogenesis via disruption of inter-organ homeostasis. Using a mouse model combining acute lung injury and hindlimb immobilization, we observed PICS-like features including muscle atrophy, lung inflammation, and neurobehavioral abnormalities such as anxiety-like behavior and special working memory. Single-cell RNA sequencing in brain revealed upregulation of gene programs associated with Alzheimer disease, depression, and neuroinflammation, particularly in endothelial cells and microglia. Concurrently, Apelin-APJ signaling was downregulated in skeletal muscle. These changes were exacerbated in Apelin-deficient mice and attenuated by muscle-specific Apelin overexpression, which also reduced systemic IL-6 and restored circulating Apelin levels. In ARDS survivors with severe COVID-19, ICU-acquired weakness (ICU-AW) was associated with reduced plasma Apelin and elevated IL-6 levels. Transcriptomic profiling of peripheral blood mononuclear cells from ICU-AW patients showed gene expression signatures linked to depression and neurodegeneration, mirroring murine findings. These data suggest that impaired Apelin-APJ signaling may play a role in PICS pathophysiology. While skeletal muscle appears to contribute to systemic Apelin levels, further studies are needed to clarify tissue-specific roles. Modulating this pathway could offer a therapeutic strategy to mitigate long-term outcomes in ICU survivors.
2. Cost-Effectiveness of In-Bed Cycling and Routine Physiotherapy for Patients Receiving Mechanical Ventilation.
Among 360 ventilated ICU patients, adding early in-bed cycling (per-patient program cost CA$321) to usual physiotherapy yielded no significant differences in 90-day costs or QALYs versus usual care. The probability of cost-effectiveness was 0.19 at a CA$50,000 per QALY willingness-to-pay threshold.
Impact: Provides trial-based economic evidence challenging routine adoption of in-bed cycling for short-term value, informing ICU rehabilitation resource allocation.
Clinical Implications: Routine addition of in-bed cycling solely for economic benefit is not supported over 90 days. Programs should consider broader outcomes, patient selection, and longer time horizons before implementation.
Key Findings
- Trial-based economic evaluation of 360 ICU patients across 16 centers found no significant differences in 90-day costs or QALYs between cycling+physiotherapy and physiotherapy alone.
- Per-patient cycling program cost was CA$321 (≈0.5% of index hospitalization costs).
- The probability of cost-effectiveness was 0.19 at a $50,000/QALY willingness-to-pay threshold.
Methodological Strengths
- Randomized trial-based economic evaluation with multicenter, international recruitment
- Societal perspective with standardized cost and QALY measurement over a defined 90-day horizon
Limitations
- 90-day time horizon may miss longer-term benefits of cycling on function and quality of life
- Potential underpowering to detect small QALY differences; generalizability may vary across health systems
Future Directions: Longer-horizon cost-effectiveness analyses incorporating 6–12 month functional outcomes and stratified evaluations to identify subgroups most likely to benefit.
IMPORTANCE: The cost-effectiveness of adding early in-bed cycling to usual physiotherapy among adults receiving mechanical ventilation in the intensive care unit (ICU) compared with usual physiotherapy alone is unknown. OBJECTIVE: To evaluate the cost-effectiveness of in-bed cycling plus usual physiotherapy compared with usual therapy alone in the Critical Care Cycling to Improve Lower Extremity Strength (CYCLE) randomized clinical trial. DESIGN, SETTING, AND PARTICIPANTS: This trial-based economic evaluation with a 90-day time horizon compared early cycling plus usual physiotherapy vs usual physiotherapy alone from a societal perspective. Adult ICU patients (aged ≥18 years) receiving mechanical ventilation were recruited from 16 ICUs in Canada, the US, and Australia. Enrollment occurred from November 1, 2016, to May 30, 2023, with the last follow-up on August 3, 2023. INTERVENTIONS: Intervention group participants were offered 30 minutes per day of cycling in addition to usual physiotherapy on weekdays, starting within the first 4 days of mechanical ventilation. Cycling continued until the patient could march on the spot for 2 consecutive days, ICU discharge, or for 28 days, whichever occurred first. Usual care participants were offered individualized physiotherapy according to local practices and patient alertness. MAIN OUTCOMES AND MEASURES: Differences in costs (in 2024 Canadian dollars [CA$]) and quality-adjusted life-years (QALYs) between the groups were calculated.
3. Practice Pattern Variability in the Use of Pulmonary Arterial Catheters in Cardiac Surgery.
In 145,343 cardiac surgeries across 53 US academic hospitals, intraoperative PACs were used in 72% of cases with extreme variability across sites (0–98%) and clinicians (0–100%). Hospital practice patterns dominated utilization (MOR 15.0), far outweighing anesthesiologist-level variation within hospitals.
Impact: Reveals substantial, hospital-driven variation in invasive monitoring for cardiac surgery, highlighting opportunities for standardization and value-based care.
Clinical Implications: Institutions should develop evidence-informed indications and auditing for PAC use, focusing on high-variance procedures and hospital-level practice to reduce unwarranted variation.
Key Findings
- PACs were used in 72% of 145,343 cardiac surgeries; utilization ranged 0–98% across hospitals and 0–100% across anesthesiologists.
- Hospital practice patterns were the dominant determinant of PAC use (MOR 15.00; 95% CI, 8.98–28.32), with smaller within-hospital anesthesiologist variation (MOR 1.70).
- Highest PAC use in heart (94%) and lung (87%) transplants; lowest in pulmonic valve procedures (30%).
Methodological Strengths
- Very large, multicenter registry with mixed-effects modeling to partition variance
- Objective PAC ascertainment using physiologic signal criteria and MOR to quantify practice variation
Limitations
- Observational design susceptible to residual confounding and misclassification despite physiologic definitions
- Findings from US academic centers may not generalize to nonacademic/community settings
Future Directions: Develop and test consensus-based indications and hospital-level feedback interventions to reduce unwarranted variability and evaluate impact on outcomes and costs.
OBJECTIVES: To quantify intraoperative pulmonary arterial catheter (PAC) use during cardiac surgery and identify hospital-, anesthesiologist-, and patient-level factors associated with PAC utilization. DESIGN: A cross-sectional, observational study using generalized logistic mixed models to examine variations in PAC use. SETTING: Fifty-three US academic hospitals participating in the Multicenter Perioperative Outcomes Group (MPOG) national registry PARTICIPANTS: 145,343 adult patients undergoing cardiac surgery between January 1, 2016, and December 31, 2022. INTERVENTION(S): Receipt of intraoperative PAC, defined by ≥60 minutes of physiologically plausible pulmonary arterial pressures. MEASUREMENTS & MAIN RESULTS: The primary outcome was PAC utilization. Mixed-effects logistic regression quantified fixed-effect predictors, and variation attributable to anesthesiologists and then to anesthesiologists nested within a hospital was characterized using median odds ratio (MOR). Of the 145,343 cardiac surgeries performed across 53 hospitals, 104,626 (72%) included PAC monitoring. PAC use varied widely across hospitals (0-98%) and across anesthesiologists (0-100%). PAC was used most frequently in heart transplants (94%) and lung transplants (87%) and least frequently in pulmonic valve procedures (30%). A patient's likelihood of receiving a PAC was influenced most strongly by hospital (MOR, 15.00; 95% confidence interval [CI], 8.98-28.32), with substantially less variation attributable to an anesthesiologist within the same hospital (MOR, 1.70; 95% CI, 1.61-1.81). CONCLUSIONS: Intraoperative PAC monitoring is used in nearly three-quarters of cardiac surgeries at US academic centers, with hospital practice pattern the factor most closely associated with PAC utilization.