Daily Anesthesiology Research Analysis
Three impactful anesthesiology/critical-care studies emerged: a large multicenter cohort linked medication-induced deep sedation during mechanical ventilation to loss of independent living; a meta-analysis found serratus anterior plane block provides analgesia comparable to thoracic paravertebral block with less hypotension; and a deep-learning analysis identified five physiologic endotypes of intraoperative hypotension that may enable causal, phenotype-guided therapy.
Summary
Three impactful anesthesiology/critical-care studies emerged: a large multicenter cohort linked medication-induced deep sedation during mechanical ventilation to loss of independent living; a meta-analysis found serratus anterior plane block provides analgesia comparable to thoracic paravertebral block with less hypotension; and a deep-learning analysis identified five physiologic endotypes of intraoperative hypotension that may enable causal, phenotype-guided therapy.
Research Themes
- ICU sedation strategy and functional outcomes
- Comparative effectiveness in regional anesthesia
- AI-driven hemodynamic phenotyping for intraoperative hypotension
Selected Articles
1. Association of medication-induced deep sedation and emotional distress during mechanical ventilation with loss of independent living: an observational cohort study.
In a 20-ICU cohort of 10,204 ventilated adults, a higher proportion of time in medication-induced deep sedation (RASS −3 to −5) during the first ICU week was independently associated with loss of independent living (in-hospital death or discharge to long-term care). Deep sedation occurred far more often than explicitly ordered, and mediation analysis suggested that reduced patient mobility partially explains the association.
Impact: This large, multicenter study provides actionable evidence that deep sedation exposure, not emotional distress, is linked to worse functional disposition after mechanical ventilation, reinforcing guideline-concordant light sedation strategies.
Clinical Implications: Prioritize light sedation, frequent mobility, and recognition of distress over deep sedation to improve functional disposition. Implement sedation quality monitoring (time-in-target RASS) and mobilization protocols.
Key Findings
- High proportion of medication-induced deep sedation during the first ICU week was associated with loss of independent living.
- Deep sedation occurred 2.84-fold more often than it was ordered; 71.4% had at least one deep sedation episode.
- Mediation analysis suggested patient mobilization level partially mediates the deep sedation–outcome relationship.
Methodological Strengths
- Large multicenter cohort across 20 ICUs with 10,204 patients
- A priori confounder control, modified Poisson regression, and mediation analysis
Limitations
- Retrospective observational design with potential residual confounding
- Outcomes limited to in-hospital disposition; sedation exposure measured via RASS documentation
Future Directions: Prospective interventional trials targeting reduced deep sedation exposure and enhanced mobility should assess causal impact on functional disposition and long-term quality of life.
BACKGROUND: Deep sedation can be used during invasive mechanical ventilation without proven indication to treat the signs and symptoms of emotional distress or insomnia. However, medication-induced deep sedation is associated with delayed recovery and increased mortality. We tested the hypothesis that medication-induced deep sedation, but not emotional distress, is associated with loss of independent living. METHODS: In this retrospective cohort study, we included adult patients (age ≥18 years) who lived independently before hospital admission and were mechanically ventilated for at least 24 h in any of 20 ICUs at an academic health system in the Bronx, New York (NY, USA), and adjacent counties. The primary exposure was the proportion of time spent in medication-induced deep sedation (defined as a Richmond Agitation Sedation Score of -3 to -5) within the first week of ICU admission. The secondary exposure was the proportion of time with indicators of emotional distress within the first week of ICU admission. The exposures were categorised as none, a low proportion, or a high proportion using the median (42·9% for medication-induced deep sedation and 10·7% for emotional distress) as the cutoff between low and high. The primary outcome was loss of independent living (defined as in-hospital death or postoperative discharge to a long-term skilled nursing facility). Modified Poisson regression with an a priori-defined confounder control model were used to assess the association between exposures and outcomes. Mediation analysis was done to evaluate whether patient mobilisation level during mechanical ventilation contributed to the association between deep sedation and loss of independent living. FINDINGS: Among 10 204 patients receiving invasive mechanical ventilation between Jan 30, 2016 and July 11, 2023, 6369 (62·4%) had a loss of independent living. The proportion of patients who received deep sedation was a mean 2·84-fold (SD 1·51) higher than the proportion of patients who had an order for deep sedation. 7289 (71·4%) patients had at least one episode of medication-induced deep sedation within the first week of mechanical ventilation in the ICU. A high proportion of medication-induced deep sedation was associated with an increased risk of loss of independent living (adjusted risk ratio [RR
2. Comparison of perioperative analgesic efficacy between serratus anterior plane block and thoracic paravertebral block in adult patients undergoing thoracic and breast surgeries: a systematic review and meta-analysis.
Across 28 RCTs (1,796 patients), serratus anterior plane block provided analgesia comparable to thoracic paravertebral block for thoracic/breast surgery. Total 24-hour opioid use was marginally higher with SAPB but below the minimal clinically important difference, and SAPB reduced hypotension risk despite slightly higher intraoperative fentanyl consumption.
Impact: This synthesis resolves a common clinical dilemma by showing SAPB is an effective, safer alternative to TPVB with fewer hypotensive events, supporting broader adoption where paravertebral block risks are a concern.
Clinical Implications: For thoracic and breast procedures, SAPB can substitute for TPVB to achieve similar analgesia with lower hypotension risk. Protocols should anticipate slightly greater intraoperative fentanyl needs without clinically meaningful increases in postoperative opioid use.
Key Findings
- No significant differences between SAPB and TPVB in time to first analgesic request or 24-hour resting pain scores.
- SAPB associated with a small increase in 24-hour opioid consumption (MD 1.73 mg MME) below the MCID threshold.
- SAPB significantly reduced hypotension risk (RR 0.39) but required slightly more intraoperative fentanyl.
Methodological Strengths
- Comprehensive search across multiple databases with randomized trials only
- Prespecified primary/secondary outcomes, random-effects modeling, and MCID contextualization
Limitations
- Heterogeneity across trials in block techniques (superficial vs deep SAPB) and surgical populations
- Variable trial quality and limited reporting of long-term outcomes
Future Directions: Head-to-head pragmatic RCTs using standardized SAPB/TPVB protocols, patient-centered outcomes, and cost-effectiveness analyses will refine block selection.
BACKGROUND: Serratus anterior plane block (SAPB) and thoracic paravertebral block (TPVB) are widely used regional anesthesia techniques for postoperative analgesia and are generally considered safe and effective. However, the comparative efficacy remains inconclusive. This systematic review and meta-analysis of randomized controlled trials (RCTs) aims to evaluate the perioperative analgesic efficacy of SAPB versus TPVB in adult patients undergoing thoracic and breast surgeries. METHODS: A comprehensive literature search was conducted in PubMed, EMBASE, Web of Science, Cochrane library, ClinicalTrial.gov, and Google Scholar up to February 28, 2025. Primary outcomes included time to first analgesic request (TFAR), 24-h total analgesic consumption (TAC) postoperatively, and 24-h postoperative pain scores at rest. Secondary outcomes comprised pain scores at various postoperative timepoints, intraoperative fentanyl consumption, length of hospital stay, patient satisfaction with analgesia, and incidence of complications. A random-effect model was applied for the meta-analysis. RESULTS: Twenty-eight 28 RCTs comprising 1796 patients were included. No significant differences were found between SAPB and TPVB in TFAR (mean difference [MD] = -0.68 h, 95% confidence interval [CI]: -1.55 to 0.18, P = 0.122), 24-h pain scores at rest (MD = 0.14, 95%CI: -0.14 to 0.42, P = 0.334), other postoperative pain scores, length of hospital stay, patient satisfaction, or incidence of postoperative nausea and vomiting (risk ratio [RR] = 0.87, 95%CI: 0.63 to 1.20, P = 0.310). Despite statistically significant, the difference of 24-h TAC comparing SAPB to TPVB (MD = 1.73 mg intravenous morphine equivalents, 95%CI: 0.54 to 2.92, P = 0.005) did not exceed the minimal clinically important difference (MCID) of 10 mg. SAPB also resulted in greater intraoperative fentanyl consumption (MD = 13.85 mcg, 95%CI: 3.86 to 23.84, P = 0.007) but a significantly lower incidence of hypotension (RR = 0.39, 95%CI: 0.20 to 0.76, P = 0.006). Subgroup analyses showed that TPVB provided superior, but non-clinically significant, opioid-sparing benefits in thoracic procedures (3.38 mg) and when compared to superficial SAPB (3.11 mg). CONCLUSION: SAPB offers comparable analgesic efficacy to TPVB, with a more favorable safety profile but slightly higher opioid consumption. However, the increased opioid use does not exceed the MCID. Therefore, SAPB is a clinically effective and safe alternative to TPVB for perioperative regional analgesia in thoracic and breast surgeries.
3. Identification of intraoperative hypotension endotypes and revolution with a temporal deep learning algorithm.
Using an LSTM autoencoder on multivariate time-series (SVRI, SVI, SVV, CI, HR), the authors identified five endotypes of intraoperative hypotension across 1,304 episodes. Temporal patterns and within-episode transitions were characterized, suggesting phenotype-specific mechanisms (vasodilation, hypovolemia, myocardial depression, bradycardia) that could enable causal, targeted therapy.
Impact: This methodological advance reframes IOH as heterogeneous endotypes with distinct mechanisms, laying groundwork for phenotype-guided vasopressor/fluids/inotrope strategies rather than one-size-fits-all MAP targets.
Clinical Implications: Intraoperative hemodynamic monitoring could be coupled with real-time classifiers to triage hypotension into endotypes and guide causal treatments (e.g., vasoconstrictors for vasodilation, fluids for hypovolemia, inotropes for myocardial depression, anticholinergics/pacing for bradycardia).
Key Findings
- Five distinct IOH endotypes identified via LSTM autoencoder and k-means: severe vasodilation (high CI), hypovolemia, myocardial depression, bradycardia, and mild vasodilation with preserved CI.
- Temporal distribution varied by endotype, and within-episode transitions between endotypes were observed.
- Approach uses high-resolution physiologic data to enable phenotype-specific mechanistic interpretation.
Methodological Strengths
- High-resolution, multivariate time-series analysis with LSTM autoencoder
- Objective clustering with CH/DB index to select optimal cluster number
Limitations
- Retrospective single-dataset analysis without external validation
- No interventional testing to confirm endotype-specific treatment benefits
Future Directions: Prospective validation and randomized trials testing endotype-guided therapy (vasopressor class, fluid responsiveness, inotropy) with real-time classifiers integrated into anesthesia monitors.
BACKGROUND: Identifying specific causes of intraoperative hypotension (IOH) is a challenge in clinical practice. Improving the causal treatment of hypotension requires a more detailed understanding of the underlying hemodynamic alterations during hypotension. This study aims to identify distinct hemodynamic endotypes of IOH by applying a deep learning model to high-resolution intraoperative hemodynamic data. METHODS: We conducted a retrospective analysis for surgical patients who had undergone continuous intraoperative monitoring of systemic vascular resistance index (SVRI), stroke volume index (SVI), stroke volume variation (SVV), cardiac index (CI), and heart rate (HR). IOH was defined as a mean arterial pressure (MAP) < 65 mmHg sustained for at least 1 min. A long short-term memory (LSTM)-based autoencoder was developed to compress multivariate time-series data into a two-dimensional latent space. Unsupervised clustering, k-means, was performed on the two-dimensional latent representations, and the optimal number of clusters was determined by Calinski-Harabasz (CH) and Davies-Bouldin (DB) index. RESULTS: A total of 184 patients experienced at least one episode of IOH, and 1304 hypotensive episodes with 253,380 data points were included for analysis. K-means identified five distinct IOH endotypes. Based on the characteristic hemodynamic profiles of each cluster, we labeled the five endotypes: (1) severe vasodilation with high CI, (2) hypovolemia, (3) myocardial depression, (4) bradycardia, and (5) mild vasodilation with preserved CI. Mild vasodilation with preserved CI occurred mainly in the first and second quartiles of the procedure. Bradycardia occurred throughout the procedure, but more frequently in the fourth quartile. Myocardial depression occurred primarily in the second quartile, and hypovolemia occurred frequently throughout the procedure. It was also observed that intra-event transitions between endotypes within the same hypotensive episode occurred in five events. CONCLUSIONS: Five endotypes of IOH were identified, and this may support the development of causal treatment strategies of intraoperative hypotension, pending future validation.