Daily Anesthesiology Research Analysis
Three perioperative studies stand out today: a 31‑trial meta-analysis finds no benefit of high inspired oxygen (FiO2) on length of stay or complications and suggests possible increased atelectasis; a randomized trial shows splenic artery ligation lowers posthepatectomy liver failure when portal pressure is high; and a nationwide analysis of 28.3 million surgeries quantifies the mortality burden of specific perioperative organ injuries, prioritizing prevention targets.
Summary
Three perioperative studies stand out today: a 31‑trial meta-analysis finds no benefit of high inspired oxygen (FiO2) on length of stay or complications and suggests possible increased atelectasis; a randomized trial shows splenic artery ligation lowers posthepatectomy liver failure when portal pressure is high; and a nationwide analysis of 28.3 million surgeries quantifies the mortality burden of specific perioperative organ injuries, prioritizing prevention targets.
Research Themes
- Perioperative oxygen strategy and postoperative outcomes
- Portal flow modulation to prevent posthepatectomy liver failure
- Population-scale risk stratification for perioperative organ injury
Selected Articles
1. Effects of high vs. low perioperative inspired oxygen fraction on length of hospital stay and postoperative complications: a systematic review, meta-analysis, and trial sequential analysis.
Across 31 RCTs (10,506 patients), high versus low FiO2 did not change length of stay, postoperative organ complications, SSI, or mortality; trial sequential analysis indicated sufficient information size for the primary outcome. Sensitivity analysis suggested high FiO2 may increase postoperative atelectasis.
Impact: Challenges guideline-endorsed high FiO2 use by showing no clinical benefit and a signal for harm (atelectasis) across diverse surgeries, with robust meta-analytic and TSA methodology.
Clinical Implications: Routine use of high FiO2 to prevent SSI should be reconsidered; individualized oxygen titration to normoxia and vigilance for atelectasis may be safer.
Key Findings
- No difference in length of hospital stay between high and low FiO2 (MD -0.01 days; 95% CI -0.10 to 0.08).
- No significant differences in postoperative cardiac, cerebral, renal, or pulmonary complications, SSI, or mortality.
- Trial sequential analysis indicated the primary outcome evidence is conclusive; sensitivity analysis suggested high FiO2 may increase postoperative atelectasis.
Methodological Strengths
- Included 31 randomized controlled trials with 10,506 participants across diverse surgeries.
- Employed random-effects meta-analysis and trial sequential analysis to assess conclusiveness.
Limitations
- Heterogeneity in FiO2 protocols and timing across trials may dilute subgroup effects.
- Signal for atelectasis depended on sensitivity analysis excluding a single study.
Future Directions: Patient-level meta-analyses and RCTs comparing titrated normoxia vs. liberal oxygen with standardized lung-protective strategies to clarify atelectasis risk and benefit-risk tradeoffs.
INTRODUCTION: Prolonged length of hospital stay (LOS) and postoperative complications in surgical patients are major public health issues worldwide. Perioperative hyperoxia may increase LOS, and the incidence of cardiac, cerebral, renal, and pulmonary injury; however, the supporting clinical evidence is controversial. Therefore, the current meta-analysis included all relevant randomized controlled trials (RCTs) to investigate the effect of high and low inspired oxygen fraction (FiO2) on LOS, according to postoperative complications. EVIDENCE ACQUISITION: Standard published RCTs were searched from bibliographic databases to identify all evidence reporting perioperative FiO2 for patients undergoing surgeries. The primary outcome was LOS, and the secondary outcomes were postoperative organ complications, surgical site infection (SSI), and postoperative mortality. The relative risk (RR) and Peto-odds ratio (Peto-OR) for dichotomous outcomes and the mean difference (MD) and standardized mean difference (SMD) for continuous outcomes were estimated using a random-effects model. Trial sequential analysis (TSA) was performed in the meta-analysis to evaluate the required information sizes and assess whether the primary outcome in our meta-analysis was conclusive. EVIDENCE SYNTHESIS: Thirty-one RCTs with 10506 participants undergoing different surgeries were included. The LOS in the high FiO2 group did not differ significantly from that in the low FiO2 group (MD -0.01, 95% CI -0.10 to 0.08, P=0.81). Moreover, we found no meaningful evidence of subgroup differences in the primary outcome, in comparisons of FiO2, RCT type, surgery type, duration of oxygen inhalation or timing of oxygen inhalation. TSA results further suggested that the number of included studies was sufficient for the primary outcome. There was also no significant difference in postoperative organ complications (cardiac, cerebral, renal, and pulmonary), SSI (rate of SSI, ASEPSIS score, and ASEPSIS score > 20 cases), or postoperative mortality. For postoperative atelectasis, sensitivity analysis showed that after exclusion of one study, "Myles 2007," high FiO2 was associated with increased postoperative atelectasis. CONCLUSIONS: The use of low FiO2 has no effect on LOS, or the incidence of cardiac, cerebral, and renal injury or postoperative mortality. Compared with low FiO2, high FiO2 did not reduce SSI which was contrary to the guidelines. Meanwhile, high FiO2 may increase postoperative atelectasis in surgical patients.
2. Impact of perioperative organ injury on morbidity and mortality in 28 million surgical patients.
In a nationwide cohort of 28.3 million surgeries, perioperative organ injury occurred in 4.4% and was associated with ninefold higher odds of death and 11.2 additional hospital days. Incidence and mortality varied by organ injury type, with acute kidney injury most frequent and liver injury carrying the highest mortality.
Impact: Provides population-scale quantification of the burden of perioperative organ injuries, enabling data-driven prioritization of prevention and quality-improvement initiatives across perioperative care.
Clinical Implications: Perioperative programs should target high-burden, high-mortality injuries (e.g., AKI, ARDS, liver injury) with specific bundles and monitoring; risk stratification and early detection protocols can be aligned with these quantified risks.
Key Findings
- Among 28,350,953 surgeries, perioperative organ injury occurred in 4.4% and increased odds of death ninefold.
- Organ injury prolonged hospitalization by an average of 11.2 days.
- Acute kidney injury was most frequent (2.0%, 25.0% mortality), while liver injury, though rarer (0.1%), had the highest mortality (68.7%).
Methodological Strengths
- Nationwide, comprehensive cohort including all elective and emergent surgeries over four years.
- Granular reporting of incidence and mortality across multiple organ injury types.
Limitations
- Administrative data subject to coding errors and residual confounding; causal inference is limited.
- Lack of granular intraoperative variables (e.g., fluids, hemodynamics) that may mediate risk.
Future Directions: Linkage with intraoperative physiologic and therapy data to identify modifiable drivers; prospective implementation of targeted prevention bundles and evaluation via learning health systems.
Perioperative organ injury contributes to morbidity and mortality of surgical patients. This cohort study included all elective and emergent surgeries in Germany over 4 years to address the impact of perioperative organ injuries on outcomes. We analyzed 28,350,953 cases. In-hospital mortality was 1.4% (n = 393,157), and 4.4% of cases (n = 1,245,898) experienced perioperative organ injury. Perioperative organ injury was associated with 9-fold higher odds of death and prolonged hospital stay by 11.2 days. Acute kidney injury had the highest incidence (2.0%) and was associated with 25.0% mortality. While delirium had the second highest incidence (1.5%), it was associated with the lowest mortality (10.8%). This was followed by acute myocardial infarction (incidence 0.6%, mortality 15.6%), stroke (incidence 0.6%, mortality 13.1%), pulmonary embolism (incidence 0.3%, mortality 20.0%), liver injury (incidence 0.1%, mortality 68.7%), and acute respiratory distress syndrome (incidence 0.1%, mortality 44.7%). These findings help prioritize interventions for preventing or treating individual types of perioperative organ injury.
3. Portal flow modulation by splenic artery ligation to prevent posthepatectomy liver failure: A randomized controlled trial.
In hepatectomy patients with portal venous pressure >15 mm Hg, splenic artery ligation lowered portal pressures and reduced clinically significant posthepatectomy liver failure (16.7% vs 66.7%), ascites burden, and comprehensive complication index in a randomized trial halted early for benefit.
Impact: Introduces a simple, physiology‑targeted intraoperative maneuver that significantly reduces posthepatectomy liver failure in high‑risk patients, with immediate translational relevance.
Clinical Implications: In patients with elevated intraoperative portal venous pressure, splenic artery ligation can be considered to modulate portal inflow and reduce PHLF; requires team protocols for pressure monitoring and selection.
Key Findings
- Among patients with portal venous pressure >15 mm Hg, splenic artery ligation reduced PHLF grades B/C from 66.7% to 16.7% (P = .006).
- Significant reductions in portal venous pressure and PVP–CVP gradient compared with control and pre-ligation values.
- Lower comprehensive complication index (8.70 vs 20.90) and reduced ascites volume with ligation.
Methodological Strengths
- Randomized controlled design targeting a physiologically defined high-risk subgroup (PVP >15 mm Hg).
- Clinically meaningful composite outcomes (PHLF B/C, CCI, ascites) with consistent benefit.
Limitations
- Single-center trial with early termination and small randomized sample, which may overestimate effect sizes.
- Generalizability limited to patients with measured elevated portal venous pressure undergoing open hepatectomy.
Future Directions: Multicenter RCTs with standardized portal pressure monitoring, assessment of long-term outcomes, and integration with other inflow modulation strategies.
BACKGROUND: Posthepatectomy liver failure is a serious clinical issue with high mortality, similar in pathophysiology to small-for-size syndrome seen in liver transplantation. This study evaluates the efficacy of splenic artery ligation in reducing posthepatectomy liver failure in patients with portal venous pressure >15 mm Hg after hepatectomy. METHODS: This single-center, randomized controlled trial was conducted from May 2019 to November 2023. Eligible participants were patients scheduled for open hepatectomy for any indication. Patients with a portal venous pressure >15 mm Hg were randomized into splenic artery ligation and control groups in a 1:1 ratio. The primary outcomes were posthepatectomy liver failure grades B and C (International Study group of Liver Surgery criteria), and secondary outcomes included 90-day mortality, comprehensive complication index, and ascites volume. RESULTS: The study was terminated early, before reaching the calculated sample size, because the primary outcome in the intervention group demonstrated statistically significant results. Of the 92 patients, 36 had elevated portal venous pressure, which was associated with greater rates of posthepatectomy liver failure grades B and C (41.67% vs 3.57%, P < .001), increased ascites volume (5,340 mL vs 1,055 mL, P < .001), and a greater comprehensive complication index (20.90 vs 8.70, P < .001). In the randomized subset, splenic artery ligation significantly reduced portal venous pressure and the portal venous pressure-central venous pressure gradient compared with both presplenic artery ligation values and the control group and significantly lowered the incidence of posthepatectomy liver failure grades B and C (16.67% vs 66.67%, P = .006), comprehensive complication index (8.70 vs 20.90, P = .034). Splenic artery ligation was identified as an independent factor in reducing posthepatectomy liver failure (adjusted relative risk, 0.29). CONCLUSION: Splenic artery ligation is effective in reducing posthepatectomy liver failure in patients with high portal venous pressure after hepatectomy.