Daily Anesthesiology Research Analysis
Analyzed 30 papers and selected 3 impactful papers.
Summary
Today’s most impactful anesthesiology findings were concentrated in perioperative pharmacology and respiratory physiology. Randomized trials showed that reducing remimazolam during cardiopulmonary bypass may stabilize free drug exposure, ciprofol may reduce respiratory depression compared with propofol, and THRIVE may preserve lung volume and substantially prolong safe apnea time in patients with obesity.
Research Themes
- Perioperative pharmacokinetic optimization during cardiopulmonary bypass
- Comparative safety of novel intravenous sedative-hypnotics
- Physiological mechanisms of apneic oxygenation in patients with obesity
Selected Articles
1. Changes in Free and Total Remimazolam Concentrations During Cardiopulmonary Bypass: A Randomized Dose-Comparison Trial.
In this randomized parallel-group trial of 36 adults undergoing cardiac surgery with cardiopulmonary bypass, free remimazolam concentrations increased over time when the infusion rate was unchanged. Reducing the infusion rate to 70% at initiation of bypass maintained free concentrations within a stable range without corresponding changes in bispectral index values.
Impact: This study addresses a clinically important pharmacokinetic problem created by hemodilution and altered protein binding during cardiopulmonary bypass. It provides a simple, immediately implementable dose-adjustment strategy that may reduce unrecognized remimazolam overexposure.
Clinical Implications: Anesthesiologists should consider reducing remimazolam infusion when cardiopulmonary bypass begins, with continued clinical and electroencephalographic monitoring. The findings support pharmacokinetically informed sedation protocols in cardiac anesthesia but require confirmation in larger and more diverse surgical populations.
Key Findings
- Thirty-six adults undergoing cardiac surgery with cardiopulmonary bypass were randomized to normal-dose or 70% reduced-dose remimazolam infusion.
- Free remimazolam concentrations increased over time with unchanged infusion during cardiopulmonary bypass.
- Reducing the infusion rate to 70% at bypass initiation maintained free remimazolam concentrations within a stable range without corresponding bispectral index changes.
Methodological Strengths
- Randomized controlled parallel-group design directly tested a pragmatic dose-adjustment strategy.
- Measurement of free and total drug concentrations addressed the clinically relevant effect of altered protein binding during cardiopulmonary bypass.
Limitations
- The sample size was small, with only 36 adults from a single university hospital.
- The abstract does not provide detailed clinical recovery outcomes or long-term postoperative outcomes.
Future Directions: Larger multicenter trials should evaluate dose adjustment across different bypass techniques, albumin concentrations, surgical durations, and sedation targets, while assessing recovery time, postoperative delirium, and patient-centered outcomes.
OBJECTIVES: Remimazolam is increasingly used in cardiac surgery for hemodynamic stability; however, during cardiopulmonary bypass (CPB), hemodilution and hypoalbuminemia may increase its pharmacologically active free fraction, raising concern about unrecognized overexposure under constant infusion. Yet, the temporal profile of free remimazolam during CPB has not been fully elucidated. We investigated whether a pragmatic dose adjustment could maintain free remimazolam concentrations within a stable range. DESIGN: Randomized, controlled, parallel-group trial. SETTING: A university hospital. PARTICIPANTS: Thirty-six adults undergoing cardiac surgery with CPB. INTERVENTIONS: Patients were assigned to a normal-dose group (1 mg/kg/h) or a low-dose group in which the infusion rate of remimazolam was reduced to 70% at CPB initiation (0.7 mg/kg/h).
2. Comparison of Incidence of Respiratory Depression Between Ciprofol versus Propofol for Procedural Sedation During First-Trimester Surgical Abortion: A Randomized Controlled Trial.
This assessor-blinded randomized controlled trial assigned 226 patients undergoing first-trimester surgical abortion to ciprofol or propofol, both combined with alfentanil. At comparable sedation depth, respiratory depression occurred less frequently with ciprofol than with propofol, while procedural sedation efficacy was similar.
Impact: The study directly compares a novel sedative with the current standard agent using a clinically important respiratory safety outcome. The observed reduction in respiratory depression may be relevant to procedural sedation practice, although external validation is needed.
Clinical Implications: Ciprofol may be considered as an alternative to propofol for selected short procedures when respiratory safety is a priority. Clinicians should interpret the findings in the context of alfentanil coadministration, pregnancy-related physiology, local availability, and the need for airway rescue capability.
Key Findings
- Two hundred twenty-six patients were randomized to ciprofol 0.4 mg/kg or propofol 2.0 mg/kg, with alfentanil administered in both groups.
- Respiratory depression occurred in 9.7% of patients receiving ciprofol versus 20.4% receiving propofol.
- Ciprofol provided comparable procedural sedation efficacy with fewer respiratory and perioperative adverse events.
Methodological Strengths
- Randomized controlled design with assessor blinding and a direct active-comparator group.
- The primary outcome addressed a clinically meaningful safety endpoint under comparable sedation conditions.
Limitations
- The trial was single-center and enrolled patients undergoing one specific procedure during the first trimester.
- Both groups received alfentanil, so the independent respiratory safety effect of ciprofol cannot be fully separated from opioid interaction.
- The study was not designed to establish rare serious airway or maternal outcomes.
Future Directions: Multicenter trials should evaluate ciprofol across broader procedural populations, different opioid regimens, difficult-airway-risk groups, and pregnancy stages, with standardized definitions of respiratory depression and patient-reported recovery outcomes.
BACKGROUND: Respiratory depression remains a major safety concern during propofol-based sedation for surgical abortion. Ciprofol is a novel intravenous sedative-hypnotic agent with pharmacological properties similar to propofol and a potentially improved safety profile. This randomized controlled trial aimed to compare the incidence of respiratory depression of ciprofol versus propofol, both combined with alfentanil, for procedural sedation in patients undergoing surgical abortion. METHODS: In this single-center, assessor-blinded, randomized controlled trial, 234 patients scheduled for surgical abortion under intravenous anesthesia were assessed for eligibility, and 226 were randomly assigned to receive either ciprofol (0.4 mg/kg; n=113) or propofol (2.0 mg/kg; n=113). Alfentanil (7.5 μg/kg) was administered intravenously as part of anesthesia induction in all patients. The primary outcome was the incidence of respiratory depression.
3. Physiological effects of trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) on lung volume dynamics during controlled apnea in patients with obesity: a randomized controlled trial.
In a randomized trial of 32 adults with obesity, THRIVE preserved global end-expiratory lung impedance more effectively than facemask oxygen during controlled apnea. It slowed the decline in lung volume and prolonged median safe apnea time from 319 to 600 seconds, providing physiological support for its use during airway management in obesity.
Impact: The study moves beyond the clinical observation that THRIVE prolongs apnea tolerance by demonstrating preservation of lung volume, particularly in specific thoracic regions. This mechanistic evidence may improve preoxygenation and airway-management strategies for patients at high risk of rapid desaturation.
Clinical Implications: THRIVE should be considered during preoxygenation and controlled apnea in patients with obesity, especially when difficult mask ventilation or prolonged laryngoscopy is anticipated. It does not eliminate the need for rapid airway control, monitoring, and rescue ventilation.
Key Findings
- Thirty-two adults with body mass index of at least 35 kg/m² were randomized to THRIVE or facemask oxygen during controlled apnea.
- Early-apnea global ΔEELI was better preserved with THRIVE than with facemask oxygen, with a mean difference of 0.67 and P < 0.001.
- Median safe apnea time was prolonged from 319 seconds with facemask oxygen to 600 seconds with THRIVE.
Methodological Strengths
- Randomized controlled design directly compared THRIVE with standard facemask oxygen.
- Electrical impedance tomography provided regional, noninvasive assessment of lung volume dynamics during apnea.
Limitations
- The study was single-center and included only 32 analyzed patients.
- The physiological and safe-apnea-time outcomes do not directly establish reductions in difficult intubation, severe hypoxemia, or perioperative complications.
- The findings may not generalize to patients with severe pulmonary disease or emergency airway management.
Future Directions: Future multicenter trials should determine whether THRIVE reduces clinically important hypoxemia and airway-management complications, and should compare it with other preoxygenation techniques in patients with varying degrees of obesity and pulmonary disease.
BACKGROUND: Obese patients are prone to rapid oxygen desaturation during induction of general anesthesia due to reduced functional residual capacity and atelectasis formation. Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) prolongs safe apnea time; however, its effects on lung volume dynamics during apnea remain unclear. METHODS: In this single-center randomized controlled trial, adults with body mass index ≥35 kg/m² were randomized to receive THRIVE or facemask oxygen during controlled apnea. Lung volume changes were assessed using electrical impedance tomography, and safe apnea time was recorded. RESULTS: Thirty-two patients were analyzed. Mean global ΔEELI during early apnea was significantly better preserved with THRIVE than with facemask oxygen (-0.22 ± 0.03 vs. -0.89 ± 0.07; mean difference 0.67, 95% CI 0.55-0.80; P < 0.001). THRIVE attenuated the rate of ΔEELI decline and was associated with greater preservation of lung volume, particularly in mid-ventral and mid-dorsal regions. Safe apnea time was significantly prolonged in the THRIVE group (median 600 vs. 319 s).