Daily Anesthesiology Research Analysis
Three impactful anesthesiology papers emerged today: a randomized controlled trial shows perioperative nitric oxide reduces AKI after cardiac surgery in CKD patients; a 7T fMRI randomized crossover study maps drug-specific effects of propofol, dexmedetomidine, and fentanyl on memory encoding and pain processing; and a network meta-analysis identifies 2-chloroprocaine as the preferred agent for short-duration ambulatory spinal anesthesia.
Summary
Three impactful anesthesiology papers emerged today: a randomized controlled trial shows perioperative nitric oxide reduces AKI after cardiac surgery in CKD patients; a 7T fMRI randomized crossover study maps drug-specific effects of propofol, dexmedetomidine, and fentanyl on memory encoding and pain processing; and a network meta-analysis identifies 2-chloroprocaine as the preferred agent for short-duration ambulatory spinal anesthesia.
Research Themes
- Perioperative organ protection and renal outcomes
- Neurocognitive and nociceptive circuit modulation by anesthetics
- Optimization of ambulatory spinal anesthesia agents
Selected Articles
1. Effects of Sedative Doses of Propofol, Dexmedetomidine, and Fentanyl on Memory and Pain in Healthy Young Adults: A Randomized, Controlled, Single-blind Crossover Study Using Functional Magnetic Resonance Imaging at 7 Tesla.
In a 92-participant single-blind randomized crossover study with 7T fMRI and concurrent painful stimulation, propofol significantly impaired next-day recollection (reduced d') and decreased hippocampus/amygdala activation for memory encoding while attenuating pain-related activation in insula and anterior cingulate. Dexmedetomidine preserved recollection and pain ratings, with limited hippocampal effects. Fentanyl altered memory and pain network activity in a distinct pattern.
Impact: This mechanistic RCT integrates 7T fMRI with controlled noxious stimulation to map drug-specific cognitive and nociceptive effects, informing sedative selection and hypotheses about intraoperative awareness and analgesia.
Clinical Implications: When amnesia is desired, propofol’s stronger impairment of recollection and limbic memory encoding may be advantageous, but its broader impact on pain networks should be considered. Dexmedetomidine may preserve memory while providing sedation, and fentanyl modulates pain networks differently; these distinctions can guide balanced sedation-analgesia strategies.
Key Findings
- Propofol reduced next-day recollection (d') versus no drug; dexmedetomidine and fentanyl did not show significant d' reductions.
- Propofol decreased memory-encoding activation in hippocampus and amygdala and reduced pain-related activation in insula and anterior cingulate.
- Fentanyl decreased primary somatosensory and insular activation during painful stimuli but increased anterior cingulate, hippocampus, and amygdala activation; dexmedetomidine had limited effects on pain processing.
Methodological Strengths
- Randomized, placebo-controlled, single-blind crossover design in 92 healthy volunteers
- Ultra–high-field (7T) fMRI with effect-site target-controlled dosing across three anesthetics and integrated painful stimulation paradigm
Limitations
- Healthy young volunteers limit generalizability to surgical patients and elderly populations
- Single-blind design and surrogate outcomes (memory tests, fMRI signals) rather than clinical endpoints
Future Directions: Extend to surgical populations across age groups, integrate EEG and clinical outcomes (awareness, delirium, pain), and test dose-response relationships to refine sedative-analgesic combinations.
BACKGROUND: Anesthetic agents are well known for their effects on memory and pain; however, previous studies quantifying anesthetic modulation of memory have not included experimental noxious stimulation. This study used functional magnetic resonance imaging to determine how low doses of propofol, dexmedetomidine, and fentanyl affect the brain systems for memory encoding and pain perception. METHODS: This was a single-blind, 1:1:1, randomized, placebo-controlled crossover study of 92 healthy volunteers ages 18 to 40 yr. Effect-site concentrations were targeted for propofol (1.0 mcg/ml), dexmedetomidine (0.15 ng/ml), or fentanyl (0.9 ng/ml). Participants listened to a series of 80 words creating a mental picture. Thirty were accompanied by a 2-s painful shock. Blood oxygen-weighted images were obtained at 7 T using a custom head coil. The primary outcome was next-day memory performance, measured by d', a normalized measure of correct identifications versus false positives. Mixed models were fit to test outcome differences between drug groups. Only statistically significant ( P < 0.05) changes are reported, after adjustment for multiple comparisons.
2. Perioperative Nitric Oxide Conditioning Reduces Acute Kidney Injury in Cardiac Surgery Patients with Chronic Kidney Disease (the DEFENDER Trial): A Randomized Controlled Trial.
In 136 CKD patients undergoing cardiac surgery with CPB, perioperative inhaled NO (80 ppm intraoperatively and for 6 h postoperatively) reduced AKI incidence (23.5% vs 39.7%; RR 0.59) and improved 6-month GFR, with fewer postoperative pneumonias and an acceptable safety profile.
Impact: This pragmatic RCT demonstrates a feasible, pharmacologic kidney-protection strategy in a high-risk surgical cohort, with both early (AKI) and longer-term (GFR) benefits.
Clinical Implications: Consider perioperative NO (80 ppm) during and shortly after CPB in CKD patients to reduce AKI risk and preserve renal function, while monitoring methemoglobin and NO2. Implementation requires NO delivery capability and multidisciplinary protocols.
Key Findings
- AKI incidence reduced from 39.7% (control) to 23.5% (NO); RR 0.59 (95% CI 0.35–0.99; P=0.043).
- Higher 6-month GFR in NO group (median 50 vs 45 ml·min−1·1.73 m−2; P=0.038).
- Lower postoperative pneumonia with NO (14.7% vs 29.4%; RR 0.5; P=0.039) and no increase in methemoglobin, NO2, or bleeding/transfusion metrics.
Methodological Strengths
- Randomized controlled design with clinically meaningful primary and secondary outcomes
- Comprehensive safety monitoring including methemoglobin and oxidative-nitrosyl stress
Limitations
- Modest sample size with confidence intervals near unity for primary outcome
- Single or limited center setting and specific CKD/CPB population may limit generalizability
Future Directions: Large multicenter trials to confirm efficacy, define optimal dosing/duration, identify responder subgroups, and evaluate cost-effectiveness and implementation at scale.
BACKGROUND: Postoperative acute kidney injury (AKI) is a significant concern for cardiac surgery patients with chronic kidney disease (CKD). Effective pharmacologic interventions to mitigate these risks are urgently needed. This study aimed to evaluate the efficacy and safety of perioperative nitric oxide (NO) administration in preventing AKI and limiting CKD progression in patients undergoing cardiac surgery. METHODS: A total of 136 patients with CKD undergoing elective cardiac surgery with cardiopulmonary bypass were randomized into two equal groups: the NO group (n = 68), receiving 80 parts per million NO during the intraoperative period and for 6 h postsurgery, and the control group (n = 68), receiving a sham treatment. The primary outcome was AKI incidence within 7 days postsurgery. RESULTS: AKI incidence was significantly lower in the NO group (16 of 68 patients, 23.5%) compared to the control group (27 of 68 patients, 39.7%) with a relative risk of 0.59 (95% CI, 0.35 to 0.99; P = 0.043). Six months postsurgery, the glomerular filtration rate was higher in the NO group (50 ml · min -1 · 1.73 m -2 [45; 54]) compared to the control group (45 ml · min -1 · 1.73 m -2 [41; 51]; P = 0.038). Postoperative pneumonia was significantly less frequent in the NO group: 10 of 68 (14.7%) versus 20 of 68 (29.4%) with a relative risk of 0.5 (95% CI, 0.25 to 0.99; P = 0.039). NO administration was safe: methemoglobin and nitrogen dioxide levels remained within acceptable ranges, oxidative-nitrosyl stress did not increase, and there were no significant differences between the groups in blood transfusion requirements, platelet counts, or postoperative blood loss volumes. CONCLUSIONS: Perioperative NO administration in CKD patients undergoing cardiac surgery with cardiopulmonary bypass is safe, reduces the incidence of AKI, and slows the progression of renal dysfunction.
3. Optimal local anesthetic for spinal anesthesia in patients undergoing ambulatory non-arthroplasty surgery: a systematic review and Bayesian network meta-analysis of randomized controlled trials.
In a network meta-analysis of 44 RCTs (3,299 patients), 2-chloroprocaine, lidocaine, and mepivacaine shortened discharge readiness, with 2-chloroprocaine ranking best across recovery metrics (shorter sensory/motor block, earlier ambulation and voiding) for ambulatory spinal anesthesia.
Impact: This synthesis provides practice-guiding comparative effectiveness evidence on short-acting spinal agents, directly informing ambulatory anesthesia protocols.
Clinical Implications: For short-duration ambulatory procedures, preferentially consider 2-chloroprocaine to expedite discharge readiness and recovery milestones, while balancing local availability and TNS/urinary retention risks compared with alternatives.
Key Findings
- Across 44 RCTs (n=3,299), 2-chloroprocaine, lidocaine, and mepivacaine improved time to discharge versus longer-acting comparators.
- 2-chloroprocaine ranked highest for shorter sensory/motor block durations, earlier ambulation, and spontaneous voiding (SUCRA-based).
- Evidence was low-to-moderate certainty; most trials involved knee arthroscopy, with limited data for arthroplasty.
Methodological Strengths
- PROSPERO-registered systematic review with network meta-analysis and CINeMA confidence assessment
- Comprehensive comparison of 11 agents across 44 RCTs with ranking (SUCRA)
Limitations
- Heterogeneity in procedures and dosing; many trials focused on knee arthroscopy, limiting generalizability to other surgeries
- Low-to-moderate certainty; insufficient RCTs for arthroplasty restricted scope
Future Directions: Head-to-head RCTs of short-acting agents in diverse ambulatory procedures, standardized dosing, and patient-centered outcomes (PONV, TNS, urinary retention, satisfaction) to refine recommendations.
PURPOSE: Dosing and types of local anesthetic agents for spinal anesthesia in ambulatory settings vary significantly. We sought to conduct a network meta-analysis to evaluate the effect of the type and dose of local anesthetic on outcomes in patients undergoing ambulatory surgery. METHODS: After PROSPERO registration (CRD42023399356), we searched various databases for randomized controlled trials (RCTs) evaluating adult patients undergoing daycare surgery under spinal anesthesia. Most included trials focused on patients undergoing knee arthroscopy, while other covered procedures were perineal, lower abdominal, and limb surgeries. Unfortunately, we could not include trials on arthroplasty surgery owing to the lack of RCTs in this area. We used Confidence in Network Meta-Analysis (CINeMA) to assess the confidence in the estimates, and we used surface under the cumulative ranking curve (SUCRA) to determine the probability rank order. The primary outcome was the time to discharge. Intraoperative effectiveness of anesthetic, sensory, and motor blockade duration; time to first micturition; time to ambulation; and adverse effects such as urinary retention and transient neurologic symptoms (TNS) were the secondary outcomes. RESULTS: Overall, this study included 44 trials comprising 3,299 patients, each comprising 11 distinct agents (2-chloroprocaine, articaine, high-dose bupivacaine, low-dose bupivacaine, lidocaine, high-dose levobupivacaine, low-dose levobupivacaine, mepivacaine, prilocaine, high-dose ropivacaine, and low-dose ropivacaine). Low- to moderate-certainty evidence showed that 2-chloroprocaine, lidocaine, and mepivacaine were superior for discharge readiness, while 2-chloroprocaine ranked highest for other outcomes (sensory and motor block duration, time to first ambulation, and spontaneous voiding). CONCLUSIONS: Evidence supports 2-chloroprocaine for short-duration spinal anesthesia in the ambulatory setting. STUDY REGISTRATION: PROSPERO ( CRD42023399356 ); first submitted 13 February 2023.