Comparison of Hemodynamics in Jet Ventilation vs. Intermittent Apnea for Airway Stenosis Surgery.

OBJECTIVE: The objective of this study is to assess the impact of two different ventilation techniques, jet ventilation and apneic anesthesia with intermittent ventilation (AAIV), on patient hemodynamics and operative time during endoscopic laryngotracheal stenosis surgery. METHODS: Retrospective chart review of patients who underwent airway dilation for laryngotracheal stenosis by a single surgeon at a single institution from October 1, 2000 through January 2, 2020. Logistic regression, Mann-Whitney U tests and chi square analysis were used to determine statistical significance. RESULTS: A total of 157 patients, 43 (27.4%) male and 114 (72.6%) female, and 605 total encounters were included for analysis. There were no significant differences in hemodynamic outcomes when comparing the AAIV and jet ventilation groups. Specifically, there was no significant difference in either peak end-tidal CO2 or nadir O2 saturation between the AAIV and jet ventilation groups (p = 0.4016) and (p = 0.1357), respectively. The patients in the AAIV group had a significantly higher median BMI 32.93 (27.40-39.40) compared with 28.80 (24.1-32.65) (p = 0.0001). Although not necessarily clinically significant, patients with higher BMI had lower median O2 nadirs (97.8%) than non-obese patients (99.2%) (p < 0.0001). The median total procedure time was equivalent when comparing the two ventilation techniques. CONCLUSION: AAIV is a safe method of ventilation for patients undergoing endoscopic laryngotracheal stenosis surgery with no significant differences in patient hemodynamics or procedure time when compared with jet ventilation. AAIV was the preferred method of ventilation for obese patients undergoing endoscopic laryngotracheal stenosis surgery. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:1343-1348, 2024.

Techniques for Measurement of Serotonin: Implications in Neuropsychiatric Disorders and Advances in Absolute Value Recording Methods.

Serotonin (5-HT) is a monoamine neurotransmitter in the peripheral, enteric, and central nervous systems (CNS). Within the CNS, serotonin is principally involved in mood regulation and reward-seeking behaviors. It is a critical regulator in CNS pathologies such as major depressive disorder, addiction, and schizophrenia. Consequently, in vivo serotonin measurements within the CNS have emerged as one of many promising approaches to investigating the pathogenesis, progression, and treatment of these and other neuropsychiatric conditions. These techniques vary in methods, ranging from analyte sampling with microdialysis to voltammetry. Provided this diversity in approach, inherent differences between techniques are inevitable. These include biosensor size, temporal/spatial resolution, and absolute value measurement capabilities, all of which must be considered to fit the prospective researcher's needs. In this review, we summarize currently available methods for the measurement of serotonin, including novel voltammetric absolute value measurement techniques. We also detail serotonin's role in various neuropsychiatric conditions, highlighting the role of phasic and tonic serotonergic neuronal firing within each where relevant. Lastly, we briefly review the present clinical application of these techniques and discuss the potential of a closed-loop monitoring and neuromodulation system utilizing deep brain stimulation (DBS).

Quantification of Cerebral Perfusion using Laser Speckle Imaging and Infarct Volume using MRI in a Pre-clinical Model of Posterior Circulation Stroke.

BACKGROUND: Basilar artery occlusion (BAO) is a subset of posterior circulation stroke that carries a mortality as high as 90%.  The current clinical standard to diagnose ischemic stroke include computerized tomography (CT), CT angiography and perfusion and magnetic resonance imaging (MRI). Large animal pre-clinical models to accurately reflect the clinical disease as well as methods to assess stroke burden and evaluate treatments are lacking. METHODS: We describe a canine model of large vessel occlusion (LVO) stroke in the posterior circulation, and developed a laser speckle imaging (LSI) protocol to monitor perfusion changes in real time.  We then utilized high b-value DWI (b=1800s/mm2) MRI to increase detection sensitivity. We also evaluated the ability of magnetic resonance angiography (MRA) to assess arterial occlusion and correlate with DSA. Finally, we verified infarct size from apparent diffusion coefficient (ADC) mapping with histology.  Results:  Administration of thromboembolism occluded the basilar artery as tracked by DSA (n=7).   LSI correlated with DSA, demonstrating a reduction in perfusion after stroke onset that persisted throughout the experiment, allowing us to monitor perfusion in real time.  DWI with an optimized b-value for dogs illustrated the stroke volume and allowed us to derive ADC and magnetic resonance angiography (MRA) images. The MRA performed at the end of the experiment correlated with DSA performed after occlusion. Finally, stroke burden on MRI correlated with histology. CONCLUSIONS: Our studies demonstrate real time perfusion imaging using LSI of a canine thromboembolic LVO model of posterior circulation stroke, which utilizes multimodal imaging important in the diagnosis and treatment of ischemic stroke.