Anesthesiology
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Randomized Controlled Trial Clinical Trial
Intracuff pressures do not predict laryngopharyngeal discomfort after use of the laryngeal mask airway.
The laryngeal mask airway (LMA) is a large foreign body that exerts pressure on the pharyngeal mucosa, which may lead to throat discomfort. To determine whether intracuff pressures are associated with such discomfort, a randomized, double-blind study was performed to determine the effect of high versus low intracuff pressures. ⋯ Differences in LMA intracuff pressures did not influence either the incidence or severity of laryngopharyngeal complaints.
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Gender-dependent differences in cytochrome P450 activity, drug metabolism, drug elimination, and their clinical consequences are increasingly apparent. P450 3A4 is the most abundant P450 isoform in the human liver and is responsible for metabolizing a vast and diverse assortment of therapeutic agents, including opioids, benzodiazepines, and local anesthetics. P450, 3A4 activity is higher in women, influenced by steroid hormone levels, and is speculated to vary during the menstrual cycle. This investigation tested the hypothesis that P450 3A4 activity varies during the menstrual cycle. Alfentanil clearance was used as a metabolic probe for P450 3A4 activity. ⋯ Alfentanil clearances were not different on menstrual cycle days 2, 13, and 21, strongly suggesting no change in P450 3A4 activity. Menstrual cycle differences in alfentanil clearances do not contribute to interindividual variability in alfentanil disposition in women. If other P450 3A4 substrates are comparable, then menstrual cycle variability in their metabolism may not be a consideration in dosing or in the design of pharmacokinetic investigations.
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Intraoperative blood pressure lability may be related to risk factors, hypovolemia, light anesthesia, and morbid outcomes, but the measurements of lability in previous studies have been limited by imprecise and infrequent data collection methods. Computerized intraoperative data acquisition systems have provided an opportunity to readdress the issue of intraoperative blood pressure lability with more abundant and precise data. This study sought to derive and validate an algorithm (expert system) to measure mean arterial pressure (MAP) lability. ⋯ One potential application of expert systems to anesthesia practice is a "smart alarm" to detect blood pressure lability. It may also provide a better tool to assess the relation between lability and outcome than has been available previously.
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Permissive hypercapnia is a ventilatory strategy aimed at avoiding lung volutrauma in patients with severe acute respiratory distress syndrome (ARDS). Expiratory washout (EWO) is a modality of tracheal gas insufflation that enhances carbon dioxide removal during mechanical ventilation by reducing dead space. The goal of this prospective study was to determine the efficacy of EWO in reducing the partial pressure of carbon dioxide (PaCO2) in patients with severe ARDS treated using permissive hypercapnia. ⋯ Expiratory washout is an effective and easy-to-use ventilatory modality to reduce PaCO2 and increase pH during permissive hypercapnia. However, it significantly increases airway pressures and lung volume through expiratory flow limitation, reexposing some patients to a risk of lung volutrauma if the extrinsic positive end-expiratory pressure is not substantially reduced.