Daily Anesthesiology Research Analysis
Analyzed 5 papers and selected 3 impactful papers.
Summary
The most impactful study developed a prospective, internally cross-validated vision-transformer approach for predicting difficult tracheal intubation and showed that additional facial poses did not improve discrimination; a pragmatic two-pose model remained only modestly predictive after accounting for selection optimism. A small randomized neurosurgical trial found comparable optic nerve sheath diameter trajectories with propofol versus propofol-ketamine anesthesia, while a large retrospective cohort showed that most difficult airways were unanticipated and that videolaryngoscopy improved glottic visualization.
Research Themes
- Artificial intelligence and airway prediction
- Neuroanesthesia and intracranial pressure surrogates
- Unexpected difficult airway management and videolaryngoscopy
Selected Articles
1. Pre-operative prediction of difficult tracheal intubation using an explainable multi-pose shared encoder vision transformer: a prospective observational study.
In 250 patients, difficult intubation occurred in 28.0%. Across all 127 facial-pose combinations, increasing the number of poses did not improve discrimination; a pragmatic upper-lip-bite plus lateral-neutral two-pose model had a mean AUC of 0.688 before nested pose-selection correction, which fell to 0.614 after accounting for optimism. Its performance was not demonstrably superior to neck circumference.
Impact: This study addresses an important airway-management problem with an explainable deep-learning framework and, importantly, demonstrates that more image acquisition is not automatically better. Its nested validation quantifies selection optimism and provides a valuable negative result against overcomplicated multi-pose protocols.
Clinical Implications: Facial-image models should not replace established airway assessment or be adopted clinically without external validation. If image-based screening is studied further, a limited two-pose protocol may reduce acquisition burden, but clinicians should recognize that its predictive performance remains modest.
Key Findings
- Difficult intubation occurred in 70 of 250 patients, or 28.0%.
- The seven-pose model had a mean AUC of 0.666, similar to the average single-pose model AUC of 0.660; discrimination was unrelated to pose number.
- Nested pose selection reduced the two-pose candidate's AUC from 0.688 to 0.614, demonstrating 0.074 AUC points of selection optimism and no external validation.
Methodological Strengths
- Prospective standardized image acquisition with five-fold cross-validation across all 127 pose combinations.
- Pose selection was nested within training folds, and calibration was assessed using a separate held-out scheme.
Limitations
- The study was single-centre with only 250 patients, limiting precision and generalizability.
- The pragmatic two-pose model had modest discrimination, predicted probabilities added little beyond prevalence, and external validation was absent.
Future Directions: Future studies should perform multicentre external validation, prespecify the pose protocol, evaluate clinically meaningful decision thresholds, and compare image-based models with integrated clinical prediction tools rather than isolated bedside tests.
BACKGROUND: Difficult tracheal intubation remains poorly predicted by conventional bedside airway tests. Facial photographs analysed by deep learning have been proposed as an alternative, and multi-pose acquisition protocols are increasingly advocated; however, whether acquiring more poses actually improves prediction has not been tested. METHODS: In this prospective, single-centre observational study, standardised pre-operative facial photographs were obtained in seven poses from 250 patients undergoing surgery under general anaesthesia with orotracheal intubation. Difficult intubation was defined pragmatically as two or more intubation attempts and/or use of an alternative airway device.
2. Comparison of propofol and propofol-ketamine anesthesia on optic nerve sheath diameter in endovascular cerebral aneurysm procedures: a prospective randomized study.
In this observer-blinded randomized trial of 40 adults undergoing elective endovascular treatment of unruptured intracranial aneurysms, propofol and propofol-ketamine produced comparable temporal trajectories of optic nerve sheath diameter. Ketamine coadministration reduced total propofol consumption and was associated with exploratory differences in hemodynamic, ventilation, anesthetic-depth, and cerebral oxygenation parameters.
Impact: The study directly tests a clinically relevant neuroanesthetic strategy using a noninvasive surrogate of intracranial pressure and a randomized design. Its main negative finding supports physiological comparability of the regimens while appropriately emphasizing that the small sample cannot establish safety or efficacy.
Clinical Implications: Propofol-ketamine anesthesia may reduce propofol requirements without an observed difference in optic nerve sheath diameter during these procedures. It should not yet be considered established as a safer neuroanesthetic regimen because the study was underpowered for complications, neurologic outcomes, and rare adverse events.
Key Findings
- The primary group-by-time interaction for mean optic nerve sheath diameter was not statistically significant.
- Total propofol consumption was significantly lower in the propofol-ketamine group.
- Exploratory group-by-time differences were observed for diastolic blood pressure, mean arterial pressure, end-tidal carbon dioxide, bispectral index, and mean regional cerebral oxygen saturation.
Methodological Strengths
- Prospective randomized allocation with observer blinding and standardized ventilation targeting normocapnia.
- Longitudinal mixed-effects modeling incorporated group, time, and group-by-time interaction for the primary outcome.
Limitations
- The sample was small, single-centre, and not powered for safety outcomes or rare adverse events.
- The trial was retrospectively registered, and secondary findings were exploratory with potential for multiplicity-related false-positive results.
Future Directions: Larger prospectively registered multicentre trials should evaluate intracranial pressure-related outcomes, cerebral perfusion, recovery profiles, neurologic outcomes, hemodynamic stability, and adverse events using prespecified hierarchical analyses.
BACKGROUND: Endovascular treatment of unruptured intracranial aneurysms requires anesthetic strategies that maintain cerebral perfusion and hemodynamic stability while avoiding increases in intracranial pressure (ICP). Optic nerve sheath diameter (ONSD) measured by ultrasonography is commonly used as a noninvasive surrogate marker of ICP. This study compared propofol and propofol-ketamine anesthesia with respect to perioperative ONSD, cerebral oxygenation, and hemodynamic parameters during endovascular aneurysm procedures. METHODS: In this prospective, randomized, single-center, observer-blinded trial, 40 adults undergoing elective endovascular treatment of unruptured intracranial aneurysms were allocated to a propofol group (P, n = 20) or a propofol-ketamine group (KP, n = 20).
3. The incidence of difficult airways in an Australian adult tertiary-quaternary hospital: a retrospective observational study of 5,293 episodes of anesthesia.
Among 5,293 adult anesthesia episodes, 207 patients had a difficult airway and 71% of these cases were unanticipated, corresponding to a 3% incidence of unanticipated difficult airway. Reduced thyromental distance, restricted neck extension, and high Mallampati scores were significant predictors, while videolaryngoscopy reduced the odds of Cormack-Lehane grade 3 or 4 views compared with direct laryngoscopy.
Impact: This large real-world cohort quantifies the substantial proportion of difficult airways that are not recognized preoperatively and provides practice-relevant evidence that videolaryngoscopy improves glottic visualization. It reinforces the limitations of prediction tests while informing airway equipment and preparedness policies.
Clinical Implications: Anesthesia services should ensure immediate availability and proficiency with videolaryngoscopy, particularly because most difficult airways may not be anticipated. Standard bedside airway predictors remain useful for risk stratification but cannot safely identify all difficult airways.
Key Findings
- Difficult airways occurred in 207 of 5,293 patients, an incidence of 4%; 146 cases, or 71% of difficult airways, were unanticipated.
- Significant predictors included reduced thyromental distance, restricted neck extension, and high Mallampati scores.
- Videolaryngoscopy was associated with lower odds of Cormack-Lehane grade 3 or 4 glottic views than direct laryngoscopy, with an odds ratio of 0.3 and 95% confidence interval of 0.2 to 0.6.
Methodological Strengths
- The cohort included 5,293 consecutive adult anesthesia episodes from contemporary tertiary-quaternary practice.
- Difficult airway classification used Canadian Airway Focus Group criteria and linked preoperative predictors with laryngoscopic outcomes.
Limitations
- The retrospective single-centre design may introduce documentation, selection, and confounding biases.
- The six-month study period and local airway practices may limit generalizability to other hospitals and patient populations.
- The observational comparison of videolaryngoscopy and direct laryngoscopy cannot establish that videolaryngoscopy independently caused improved visualization.
Future Directions: Multicentre prospective registries should evaluate first-pass success, intubation time, complications, operator experience, and patient outcomes while adjusting for indication and selection of videolaryngoscopy. Cluster-randomized implementation studies could test routine versus selective videolaryngoscopy strategies.
PURPOSE: In this study, we aimed to evaluate the incidence and anticipation rate of difficult airways in adult nonobstetric patients undergoing general anesthesia at a single tertiary-quaternary Australian hospital, and to review the predictors of difficult airways and the impact of videolaryngoscopy (VL) on glottic visualization in unanticipated difficult airway cases. METHODS: We conducted a retrospective observational study over a 6-month period. We included 5,293 adult patients who underwent general anesthesia with airway instrumentation. Data was extracted from anesthetic records. Difficult airways were defined according to the Canadian Airway Focus Group criteria.