This Week in Anesthesiology — Jun 5, 2026

Welcome to This Week in Anesthesiology. This week we're covering 10 notable papers spanning the complex drivers of postoperative delirium, challenges in hemodynamic management, and new findings in regional anesthesia and critical care. Let's dive in.

We begin with a major focus on postoperative delirium, with five papers this week adding to our understanding of this common and debilitating complication. The first set of studies explores preoperative risk factors that render our patients vulnerable. In *Anesthesiology*, a prospective study of over 800 elderly non-cardiac surgery patients investigated the link between pre-existing cerebral small-vessel disease and delirium [1]. Researchers found that a higher burden of small-vessel disease, measured on preoperative MRI, was associated with roughly doubled odds of developing postoperative delirium. The risk was progressive, reaching 28% in patients with the most severe MRI findings. Specifically, the presence of lacunes nearly tripled the risk, and white matter hyperintensities more than tripled it. The authors estimate that nearly half of all delirium cases in this cohort were potentially attributable to this underlying vascular pathology, identifying it as a crucial new risk factor. Complementing this, a study in the *Journal of Clinical Anesthesia* looked at a more readily available tool: the ultra-rapid Ascertain Dementia Eight-item Questionnaire, or AD8 [4]. Analyzing data from nearly 700 older non-cardiac surgery patients, they found that a positive screen for cognitive impairment, defined as a score of two or more, was associated with a more than 3.5-fold increase in the odds of delirium and a more than 2-fold increase in 90-day complications. Drilling down, one specific question on the AD8—asking about repetition—was a particularly strong signal, associated with a six-fold increase in delirium risk. Finally, adding a genetic dimension, another paper in *Anesthesiology* mined the UK Biobank data of over 230,000 non-cardiac surgery patients [5]. This genome-wide association study identified a significant genetic risk locus for delirium at the APOE region, the same region well-known for its link to Alzheimer's disease. The study also confirmed a powerful association between an episode of postoperative delirium and a subsequent diagnosis of dementia, with delirium sufferers having a more than 6-fold higher rate of dementia after non-cardiac surgery.

Beyond preoperative vulnerability, two studies examined intraoperative physiology. A prospective observational study in the *Canadian Journal of Anaesthesia* shifts our focus from pressure to flow [10]. Researchers used ultrasound to continuously monitor common carotid artery blood flow in 210 elderly patients undergoing abdominal surgery. They found that the duration of carotid blood flow reductions greater than 40% from baseline was a powerful independent predictor of postoperative delirium. For every 10-minute increment spent in this low-flow state, the odds of delirium more than doubled. Importantly, these low-flow episodes showed very poor correlation with traditional mean arterial pressure-based definitions of hypotension, suggesting that standard monitoring may be missing a key piece of the perfusion puzzle. This leads directly to a large systematic review and meta-analysis from *Anesthesiology* that asked if targeting higher intraoperative blood pressures improves outcomes [6]. After analyzing 15 randomized trials including over 15,000 patients, the authors concluded that targeting higher blood pressures does not reduce the risk of acute kidney injury or myocardial injury compared to routine management. However, they did find that a higher blood pressure target was associated with a significant reduction in postoperative delirium, with a relative risk of 0.73. The authors caution that this evidence is still insufficient to draw firm conclusions and warrants further investigation, but it provides an intriguing link between our hemodynamic goals and neurologic outcomes.

Staying on the topic of hemodynamics, two papers this week highlight fundamental challenges in how we define and predict intraoperative hypotension. A study in the *European Journal of Anaesthesiology* performed a systematic literature search and found a staggering 56 unique definitions of post-induction hypotension [9]. When they applied these different definitions to a prospective cohort of 720 patients, the reported incidence of hypotension swung wildly, from as low as 10% to as high as 89%, all within the same patient group. This demonstrates that who we label as 'hypotensive' depends entirely on the ruler we use, making it incredibly difficult to compare studies or create universal guidelines. This problem extends to the development of artificial intelligence tools for prediction. A paper in *Anesthesiology* provides critical methodologic insights on building early warning models for hypotension [2]. The authors show that model performance can be artificially inflated by over 70% if the evaluation dataset includes periods where the patient is already hypotensive. For a true early warning system, they recommend training models on data that excludes confounding interventions and testing them on data that excludes both interventions and periods of ongoing hypotension, a crucial standard for future research in this area.

Next, we have an important update in regional anesthesia. For total knee arthroplasty, we often debate the merits of a single-injection peripheral nerve block versus a continuous catheter. A randomized controlled trial in *Regional Anesthesia and Pain Medicine* provides a clear answer in one common scenario [3]. Ninety-four patients were randomized to either a single-injection adductor canal block with perineural dexamethasone or a continuous adductor canal catheter infusion. Both groups also received a robust multimodal regimen including an iPACK block and periarticular infiltration. The primary outcome was opioid consumption between 24 and 48 hours postoperatively. The study found no statistically significant difference between the groups. The continuous catheter did not reduce opioid consumption compared to the enhanced single-shot block. This suggests that within a comprehensive multimodal analgesic plan, a continuous adductor canal catheter may not provide additional benefit, potentially simplifying care and resource use.

Finally, we turn to two papers from the world of critical care. The first, in *Critical Care Medicine*, gives us a clearer picture of a devastating condition: refractory septic shock [8]. Using recently developed consensus criteria—defined as requiring a norepinephrine equivalent dose over 0.5 micrograms per kilogram per minute with a lactate over 2 mmol/L—researchers analyzed a large United States health system database. They found that refractory septic shock occurred in about one in five patients with septic shock. The outcome was grim: hospital mortality was 64.4%, and the risk-adjusted odds of dying were nearly five times higher compared to patients with septic shock that did not meet these refractory criteria. This study validates the new definition and provides crucial prognostic data. On a more optimistic note, another study in *Critical Care Medicine* showcases an innovative care delivery model [7]. It describes the implementation of comprehensive remote respiratory therapy, or eRT, in an eight-bed ICU dedicated to brain-dead organ donors. Over a 12-month period, remote therapists performed full ventilator management and procedural support via a telecritical care platform. The model proved to be safe, with no airway losses or delays in care. It also had a major operational impact, saving an estimated 2.2 full-time employee positions and over $300,000 in labor costs, all while maintaining excellent organ procurement rates. This provides a strong proof-of-concept for expanding the role of telemedicine in the ICU.

If you only have time for one paper this week, make it the randomized trial in *Regional Anesthesia and Pain Medicine* comparing single-shot versus continuous adductor canal blocks for knee arthroplasty [3]. It directly addresses a common clinical decision point, suggesting that for TKA within a modern multimodal regimen, a continuous catheter doesn't offer an opioid-sparing benefit over a single-injection block with perineural dexamethasone, potentially simplifying care without compromising analgesia.

Here are the key takeaways from this week in Anesthesiology: First, the risk of postoperative delirium is strongly tied to pre-existing patient factors. Be aware that underlying cerebral small-vessel disease on MRI, a positive AD8 cognitive screen, and APOE genetics are all major red flags. Intraoperatively, prolonged carotid blood flow reduction may be a more specific indicator of cerebral hypoperfusion than MAP alone. Second, our approach to intraoperative hypotension remains a work in progress. The lack of a standard definition complicates both research and clinical practice. A large meta-analysis suggests that simply targeting a higher MAP doesn't reduce major organ injury, although a potential benefit for delirium prevention warrants more study. Third, for total knee arthroplasty, a single-injection adductor canal block fortified with perineural dexamethasone appears to be as effective as a continuous catheter when used as part of a comprehensive multimodal plan that includes an iPACK block and periarticular infiltration. Finally, in the ICU, remember that about one in five patients with septic shock will meet the criteria for refractory shock, which carries a grim prognosis with over 60% mortality. At the same time, innovations like remote respiratory therapy are proving to be safe and effective ways to deliver high-quality care and address staffing challenges.

That's your roundup for This Week in Anesthesiology. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

This is an automated summary generated by artificial intelligence, which can make mistakes. Always review the original source materials.