Daily Anesthesiology Research Analysis
Three impactful anesthesiology studies emerged: a randomized trial showing perioperative dexmedetomidine reduced 30-day major complications in high-risk non-cardiac surgery; a randomized trial demonstrating preemptive left stellate ganglion block cut the incidence and severity of cardiac surgery–associated acute kidney injury; and a mechanistic Anesthesiology study revealing cerebral arteries increase compliance during norepinephrine-induced hypertension, unlike systemic arteries.
Summary
Three impactful anesthesiology studies emerged: a randomized trial showing perioperative dexmedetomidine reduced 30-day major complications in high-risk non-cardiac surgery; a randomized trial demonstrating preemptive left stellate ganglion block cut the incidence and severity of cardiac surgery–associated acute kidney injury; and a mechanistic Anesthesiology study revealing cerebral arteries increase compliance during norepinephrine-induced hypertension, unlike systemic arteries.
Research Themes
- Perioperative organ protection and complication reduction
- Autonomic/regional techniques to prevent cardiac surgery–associated acute kidney injury
- Cerebrovascular compliance and pressor-induced hypertension physiology
Selected Articles
1. Preemptive left stellate ganglion block reduces the incidence and severity of cardiac surgery-associated acute kidney injury: a randomized clinical trial.
In a randomized trial (n=138), preemptive left stellate ganglion block performed after induction significantly reduced the incidence (14.5% vs 40.6%) and severity of cardiac surgery–associated AKI within 7 days, with corroborating improvements in renal artery Doppler indices and inflammatory and catecholamine markers. Benefits were consistent in ITT and per-protocol analyses.
Impact: Introduces a simple, low-cost regional technique that substantially reduces AKI after cardiopulmonary bypass—a high-impact complication with few effective preventives.
Clinical Implications: Consider left stellate ganglion block after induction in on-pump cardiac surgery patients at risk for AKI, with intraoperative renal Doppler monitoring to assess perfusion; integrate into multimodal organ protection pathways.
Key Findings
- AKI incidence reduced from 40.6% (control) to 14.5% (SGB) in ITT analysis (RR 0.351, P=0.005).
- AKI severity significantly lower with SGB (P<0.001) in both ITT and PP analyses.
- Post-CPB left renal artery RI and PI were lower in SGB group (P<0.001 and P=0.005).
- Perioperative IL-6, CRP, and norepinephrine were significantly reduced with SGB.
- Sensitivity analyses confirmed robustness of the effect (benefit ratio for AKI incidence 0.244, P=0.003).
Methodological Strengths
- Randomized clinical trial with both ITT and per-protocol analyses.
- Physiological (renal Doppler) and biomarker endpoints support mechanistic plausibility.
Limitations
- Single-center study; generalizability may be limited.
- No sham block; blinding of clinicians/patients not described, potential performance bias.
Future Directions: Multicenter, blinded trials comparing left vs right SGB and sham; dose–response and timing optimization; assessment of long-term renal outcomes and integration with other renal-protective strategies.
BACKGROUND: Acute kidney injury is a common and severe complication of cardiac surgery. A connection might exist between renal sympathetic nerves and left stellate ganglion. It remains unclear whether preemptive left stellate ganglion block (SGB) can effectively prevent cardiac surgery-associated acute kidney injury (CSA-AKI) in clinical practice. METHOD: Participants were randomly assigned to SGB group with 0.375% ropivacaine 5 ml performed post-general anesthesia induction or control group (no SGB). The primary outcomes were incidence and severity of CSA-AKI within 7 days postoperatively. Secondary outcomes were intraoperative resistive index (RI) and pulsatility index (PI) of left renal artery via TEE and perioperative IL-6, CRP, and norepinephrine. RR and 95% CI were calculated to compare outcomes between groups. Sensitivity analyses were performed to confirm robustness of findings. RESULT: A total of 138 participants were randomized for intention-to-treat (ITT) analysis (69 SGB, 69 control) and 119 for per-protocol (PP) analysis (59 SGB, 60 control). In the ITT analysis, the incidence of CSA-AKI was significantly lower in the SGB group than the control group (14.5% [10/69] vs. 40.6% [28/69], RR 0.351, 95% CI: 0.169-0.728, P = 0.005). The PP analyses (13.6% [8/59] vs. 41.7% [25/60], RR 0.325, 95% CI: 0.160-0.660, P = 0.001) demonstrated similar results. The severity of CSA-AKI was significantly lower in the SGB group than the control group (ITT and PP: P < 0.001). The RI and PI were significantly lower in the SGB group than the control group at post-CPB cessation ( P < 0.001 and P = 0.005, respectively). Postoperatively, the SGB group demonstrated significant reductions in IL-6, CRP, and norepinephrine (all P < 0.05). The sensitivity analysis confirmed the robustness of the observed effects, yielding an unadjusted benefit ratio of 0.244 (95% CI: 0.096-0.620, P = 0.003) for the incidence of CSA-AKI and 0.197 (95% CI: 0.082-0.468, P < 0.001) for its severity. CONCLUSION: Preemptive left SGB effectively reduces the incidence and severity of CSA-AKI in patients undergoing cardiac surgery under CPB.
2. Perioperative dexmedetomidine reduces the risk of postoperative complications in high-risk patients undergoing non-cardiac surgery: A randomized controlled trial.
In a multicenter RCT of elderly high-risk patients (RCRI ≥3), perioperative dexmedetomidine (intraoperative plus 72-hour postoperative infusion) reduced 30-day major postoperative complications (38.2% vs 52.9%; RR 0.722) and shortened postoperative hospital stay by ~1 day, with lower peak postoperative NLR. Adverse events were similar between groups.
Impact: Demonstrates clinically meaningful complication reduction using a widely available sedative, supporting anti-inflammatory organ-protective strategies in high-risk surgery.
Clinical Implications: For elderly patients with high cardiac risk undergoing major non-cardiac surgery, a perioperative dexmedetomidine strategy may be considered to reduce complications, with attention to hemodynamics and bradycardia risk, and alongside standard ERAS pathways.
Key Findings
- Major postoperative complications reduced at 30 days (38.2% vs 52.9%; RR 0.722, 95% CI 0.554–0.942).
- Postoperative in-hospital stay shorter by ~1 day (P=0.013).
- Lower peak neutrophil-to-lymphocyte ratio in first 3 days post-op (MD -2.1; P=0.037).
- Adverse event rates comparable between groups.
Methodological Strengths
- Multicenter randomized, placebo-controlled design with predefined composite clinical endpoints.
- Integration of inflammatory biomarker (NLR) to support mechanistic plausibility.
Limitations
- Moderate sample size; trial conducted in a single country which may limit generalizability.
- Composite endpoint may obscure effects on individual complication domains; blinding details not fully elaborated.
Future Directions: Larger international RCTs to validate effect size, assess dose/timing optimization, cost-effectiveness, and impact on specific complications and long-term outcomes.
BACKGROUND: Dexmedetomidine may suppress the surgery-induced inflammatory response, which is considered the underlying mechanism of postoperative complications. This study was designed to investigate whether perioperative dexmedetomidine could decrease the risk of postoperative complications among high-risk patients. METHODS: This multicenter randomized controlled trial is a superiority trial. Central randomization was used. Elderly patients (age ≥60 years) with revised cardiac risk index (RCRI) ≥3 and scheduled for major non-cardiac surgery were enrolled. Patients in dexmedetomidine group received intraoperative dexmedetomidine (a loading dose of 0.5 μg/kg followed by 0.3 μg·kg-1·h-1) as adjuvant to general anesthesia and postoperative dexmedetomidine (2 μg/h for 72 h) as supplementation to patient-controlled analgesia with sufentanil. Patients in the control group received an equivalent dose of normal saline as placebo during anesthesia and sufentanil only for postoperative analgesia. The primary outcome was the incidence of major postoperative complications including neurologic, cardiovascular, acute kidney injury pulmonary, coagulation, infectious, and gastrointestinal systems within postoperative 30 days. Secondary outcomes included pain intensity, sleep quality, postoperative length of in-hospital stay, and medical expenses during hospitalization. Neutrophil-to-lymphocyte ratio (NLR) was used to monitor inflammatory response. RESULTS: This study included 272 patients, with similar median age (70 years vs. 69 years) and median RCRI (both 3) between dexmedetomidine and control groups. The incidence of major postoperative complications in the dexmedetomidine group was significantly lower than that in the control group (38.2% [52/136] vs. 52.9% [72/136], relative risk [RR] = 0.722, 95% confidence interval (CI) 0.554-0.942, P = 0.015). Postoperative in-hospital stay was shorter in the dexmedetomidine group than that in the control group (mean difference [MD] = -1 day, 95% CI: -2 to 0 days, P = 0.013). Other secondary outcomes were comparable between the two groups. The highest NLR within postoperative first 3 days in the dexmedetomidine group was lower than that in the control group (MD = -2.1, 95% CI: -4.1 to -0.3, P = 0.037). The proportion of all drug-related adverse events were comparable between the two groups. CONCLUSION: Dexmedetomidine, infused from the beginning of anesthesia to postoperative 72 h, decreased the risk of postoperative complications in high-risk elderly patients undergoing non-cardiac surgery. TRIAL REGISTRATION: No. ChiCTR2000030566 at www.chictr.org.cn.
3. Cerebral Blood Flow under Pressure: Investigating Cerebrovascular Compliance with Phase-contrast Magnetic Resonance Imaging during Induced Hypertension.
In 18 healthy adults, norepinephrine-induced 20% MAP increase led to significant increases in cerebral arterial compliance (C_WK +110%, C_VP +11%), while systemic aortic compliance did not increase similarly. Cerebral arterial cross-sectional area decreased slightly as aortic areas increased, indicating distinct cerebrovascular adaptation to pressor therapy.
Impact: Provides mechanistic evidence that cerebral arteries dynamically enhance compliance under induced hypertension, informing safer pressor strategies in neurocritical care (e.g., vasospasm management).
Clinical Implications: When using norepinephrine for induced hypertension (e.g., post-SAH vasospasm), cerebral arteries may buffer pulsatility via increased compliance, differing from systemic arteries; dosing strategies should consider cerebrovascular-specific responses.
Key Findings
- Cerebral compliance increased significantly with pressor: C_WK +110% (P=0.001) and C_VP +11% (P=0.018).
- External carotid C_WK increased (+12%), while ascending/descending aortic C_WK did not change.
- Descending aortic C_VP decreased (-5%), indicating divergent systemic response.
- Cerebral arterial cross-sectional area decreased by ~5%, whereas aortic areas increased (7–8%).
Methodological Strengths
- Within-subject design with controlled 20% MAP increase using norepinephrine.
- Advanced PCMRI quantification with dual compliance modeling (Windkessel and volume/pressure).
Limitations
- Small sample (n=18) of healthy adults; findings may not generalize to patients with cerebrovascular disease.
- Short-term physiological endpoints without clinical outcomes.
Future Directions: Extend to patient populations (e.g., SAH vasospasm), assess dose–response and duration, and link compliance changes to clinical outcomes and microcirculatory injury markers.
BACKGROUND: Induced hypertension is used clinically to increase cerebral blood flow (CBF) in conditions such as vasospasm after subarachnoid hemorrhage. However, increased blood pressure also raises pulsatile force. Cerebrovascular compliance plays a key role in buffering flow dynamics and protecting the microcirculation, but whether it adapts to elevated pressure remains unclear. This study assessed the response of compliant cerebral arteries to induced hypertension in healthy adults using phase-contrast magnetic resonance imaging (PCMRI) and two compliance models: a two-element Windkessel (compliance estimated using the Windkessel model, C WK ) and a simplified model (compliance calculated as the ratio of pulsatile volume to pressure, C VP ), representing the extremes of pulsatility transmission at the capillary level. METHODS: Eighteen healthy adults (median age, 34 yr; nine women) underwent PCMRI at baseline and after increasing mean arterial pressure by 20% using norepinephrine infusion. PCMRI quantified CBF and cardiac output, while cerebrovascular resistance and systemic vascular resistance were derived. Flow waveforms were combined with blood pressure to assess C WK and C VP in CBF, ascending/descending aorta, and external carotid arteries, while corresponding regions of interest were used to calculate cross-sectional flow areas. Data are reported as median (interquartile range). RESULTS: Norepinephrine increased cerebrovascular compliance significantly: C WK by 110% (56 to 163%; P = 0.001) and C VP by 11% (-2 to 26%; P = 0.018). C WK increased in the external carotid artery by 12% (1 to 32%; P = 0.037) but did not change in the ascending or descending aorta. C VP decreased in the descending aorta by 5% (-11 to 2%; P = 0.028), with no changes in the ascending aorta or external carotid artery. Cross-sectional area of cerebral arteries contributing to CBF decreased by 5% (-17 to -3%; P = 0.033), while the ascending and descending aorta areas increased by 7% (4 to 11%; P = 0.012) and 8% (6 to 11%; P < 0.001), respectively. CONCLUSIONS: Cerebral arteries enhanced their compliance during norepinephrine-induced hypertension, unlike systemic arteries, regardless of the assumed degree of pulsatility transmission.