Anesthesiology
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During the COVID-19 pandemic, ventilator sharing was suggested to increase availability of mechanical ventilation. The safety and feasibility of ventilator sharing is unknown. ⋯ Custom designed three-dimensional printed inspiratory flow control valves designed to allow individualized setting of tidal volume and airway pressure were evaluated using high-fidelity simulator mannequins with similar or different lung compliance and were found to perform as expected with stable tidal volumes delivered to each mannequin.Testing for 60 min in two pairs of volunteer COVID-19 patients with acute respiratory failure, matched on positive end-expiratory pressure level, fractional inspired oxygen tension level, and respiratory rate, demonstrated stable system performance. Continuous assessment of tidal volume and peak airway pressure in each patient during the study allowed for dynamic alteration of tidal volume in response to respiratory acidosis.This study suggests that custom designed flow control valves may facilitate the use of split ventilation techniques in a surge setting.
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Esophageal balloon calibration was proposed in acute respiratory failure patients to improve esophageal pressure assessment. In a clinical setting characterized by a high variability of abdominal load and intrathoracic pressure (i.e., pelvic robotic surgery), the authors hypothesized that esophageal balloon calibration could improve esophageal pressure measurements. Accordingly, the authors assessed the impact of esophageal balloon calibration compared to conventional uncalibrated approach during pelvic robotic surgery. ⋯ In a clinical setting with variable chest wall mechanics, uncalibrated measurements substantially overestimated absolute values and underestimated respiratory variations of esophageal pressure. Calibration could substantially improve mechanical ventilation guided by esophageal pressure.
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Postoperative pain caused by trauma to nerves and tissue around the surgical site is a major problem. Perioperative steps to reduce postoperative pain include local anesthetics and opioids, the latter of which are addictive and have contributed to the opioid epidemic. Cryoneurolysis is a nonopioid and long-lasting treatment for reducing postoperative pain. However, current methods of cryoneurolysis are invasive, technically demanding, and are not tissue-selective. This project aims to determine whether ice slurry can be used as a novel, injectable, drug-free, and tissue-selective method of cryoneurolysis and resulting analgesia. ⋯ Ice slurry injection selectively targets the rat sciatic nerve, causing no damage to surrounding tissue. Injection of ice slurry around the rat sciatic nerve induced decreased nociceptive response from the baseline through neural selective cryoneurolysis.
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The neural circuits underlying the distinct endpoints that define general anesthesia remain incompletely understood. It is becoming increasingly evident, however, that distinct pathways in the brain that mediate arousal and pain are involved in various endpoints of general anesthesia. To critically evaluate this growing body of literature, familiarity with modern tools and techniques used to study neural circuits is essential. ⋯ Each technique is explained, including the advantages, disadvantages, and other issues that must be considered when interpreting experimental results. Examples are provided of studies that probe mechanisms of anesthesia using each technique. This information will aid researchers and clinicians alike in interpreting the literature and in evaluating the utility of these techniques in their own research programs.