Daily Anesthesiology Research Analysis
Three anesthesiology-relevant studies stand out today: a large international RCT (PROTHOR) shows no benefit of high PEEP with recruitment during one-lung ventilation and more intraoperative complications; an international cohort (ALICE) details the high prevalence and multifactorial etiology of preoperative anemia; and an RCT in TKA suggests liposomal bupivacaine for adductor canal block lowers pain scores and opioid use without changing the proportion with moderate-to-severe pain.
Summary
Three anesthesiology-relevant studies stand out today: a large international RCT (PROTHOR) shows no benefit of high PEEP with recruitment during one-lung ventilation and more intraoperative complications; an international cohort (ALICE) details the high prevalence and multifactorial etiology of preoperative anemia; and an RCT in TKA suggests liposomal bupivacaine for adductor canal block lowers pain scores and opioid use without changing the proportion with moderate-to-severe pain.
Research Themes
- Intraoperative ventilation strategies during one-lung ventilation
- Preoperative anemia epidemiology and etiology in major surgery
- Optimization of regional analgesia for total knee arthroplasty
Selected Articles
1. Effects of intraoperative higher versus lower positive end-expiratory pressure during one-lung ventilation for thoracic surgery on postoperative pulmonary complications (PROTHOR): a multicentre, international, randomised, controlled, phase 3 trial.
In this 28-country phase 3 RCT of 2200 thoracic surgery patients undergoing one-lung ventilation, a high PEEP plus recruitment strategy did not reduce postoperative pulmonary complications versus low PEEP without recruitment. High PEEP increased intraoperative hypotension and arrhythmias, whereas hypoxemia rescue maneuvers were more frequent with low PEEP.
Impact: This definitive trial challenges routine use of high PEEP with recruitment during one-lung ventilation by showing no clinical benefit and more intraoperative instability, informing ventilation strategies globally.
Clinical Implications: Avoid routine high PEEP with recruitment during one-lung ventilation in patients with BMI <35 kg/m2; adopt lower PEEP/permissive atelectasis with individualized rescue strategies to balance oxygenation and hemodynamics.
Key Findings
- Primary outcome (postoperative pulmonary complications) was similar: 53.6% (high PEEP) vs 56.4% (low PEEP); absolute risk difference −2.68 pp (95% CI −6.36 to 1.01); p=0.155.
- High PEEP increased intraoperative complications: hypotension 37.3% vs 14.3% and new arrhythmias 9.9% vs 3.9%.
- Hypoxemia rescue maneuvers were more frequent with low PEEP (8.8% vs 3.3%).
- No differences in extrapulmonary postoperative complications or total adverse events between groups.
Methodological Strengths
- Large, multicentre, international randomized phase 3 trial with 2200 participants.
- Modified intention-to-treat analysis and prespecified outcomes relevant to thoracic anesthesia.
Limitations
- BMI ≥35 kg/m2 patients were not included, limiting generalizability to severe obesity.
- Blinding of intraoperative ventilation strategy is not feasible, potentially introducing performance bias.
Future Directions: Evaluate individualized PEEP titration and alternative lung-protective strategies in subgroups (e.g., obesity, compromised lung function) and assess longer-term pulmonary outcomes.
2. The aetiology and prevalence of preoperative anaemia in patients undergoing major surgery (ALICE): an international, prospective, observational cohort study.
In a 79-center, 20-country prospective cohort of 2702 major-surgery patients, preoperative anemia was common (31.7%). Among those with confirmed etiologies, iron deficiency predominated (55.2%), but vitamin B12 (7.7%) and folate (14.5%) deficiencies were substantial, indicating the need for a broader workup than iron alone.
Impact: Provides granular, international evidence on preoperative anemia etiologies, supporting comprehensive patient blood management beyond iron supplementation.
Clinical Implications: Preoperative anemia screening should include iron studies as well as vitamin B12 and folate assessments; protocols should address multifactorial etiologies to optimize perioperative outcomes.
Key Findings
- Preoperative anemia prevalence was 31.7% among 2702 major-surgery patients.
- Among 782 with confirmed etiologies, iron deficiency accounted for 55.2%; vitamin B12 deficiency 7.7%; folate deficiency 14.5%; chronic kidney disease 8.7%.
- Iron deficiency was the most prevalent etiology across sex, age groups, and countries.
Methodological Strengths
- Prospective, multicentre design across 79 hospitals in 20 countries.
- Standardized definitions and broad inclusion reflecting real-world surgical populations.
Limitations
- Etiology analysis limited to a subset with confirmatory data (782/856 anaemic patients), which may introduce selection bias.
- Observational design precludes causal inference regarding outcomes or treatment effects.
Future Directions: Investigate targeted, multimodal correction pathways (iron, B12, folate, CKD management) and quantify impacts on transfusion rates and postoperative outcomes in interventional trials.
3. Liposomal Bupivacaine Versus Ropivacaine With Perineural Dexamethasone in Adductor Canal Block for Total Knee Arthroplasty: A Randomized Clinical Trial.
In 72 TKA patients randomized to ACB with liposomal bupivacaine vs ropivacaine plus perineural dexamethasone, the 48-hour incidence of moderate-to-severe pain with movement was not different. Liposomal bupivacaine reduced pain scores, opioid use, and improved recovery quality at 24–48 hours without increasing adverse events.
Impact: Addresses a common perioperative analgesic decision in TKA using an active comparator and patient-centered outcomes, informing cost–benefit considerations of liposomal formulations.
Clinical Implications: Liposomal bupivacaine ACB may be considered to lower pain intensity and opioid consumption and enhance recovery quality, though it may not reduce the proportion with moderate-to-severe pain at 48 hours; cost and availability should guide selection.
Key Findings
- Primary endpoint was not different: moderate-to-severe pain with movement at 48 h was 47.2% vs 63.9% (RR 0.71; 95% CI 0.43–1.16; P=0.149).
- Liposomal bupivacaine lowered NRS pain scores at rest and with movement at 24 and 48 h and reduced opioid consumption 0–24 h and 24–48 h (both P<0.05).
- Quality of recovery improved at 24 and 48 h in the liposomal group; adverse event rates were similar between groups.
Methodological Strengths
- Prospective randomized design with active comparator and prespecified patient-centered outcomes.
- Clinically relevant block (adductor canal) preserving quadriceps strength.
Limitations
- Modest sample size (n=72) may limit power for the primary endpoint and subgroup analyses.
- Short follow-up limited to 48 hours; longer-term outcomes (function, opioid-related adverse effects) not assessed.
Future Directions: Larger multicentre RCTs with cost-effectiveness analyses and longer follow-up should assess functional recovery, persistent pain, and opioid-related harms.