Anesthesiology
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Biography Historical Article
Horace Wells' Demonstration of Nitrous Oxide in Boston.
Horace Wells, a dentist in Hartford, Connecticut, first used nitrous oxide in dentistry in December 1844. A few weeks later he travelled to Boston, Massachusetts, to demonstrate to physicians and dentists the use of nitrous oxide in painful procedures. Wells' unsuccessful demonstration of nitrous oxide for the extraction of a tooth is well known, but other details of this trip are poorly understood. ⋯ The precise date and location of Wells' demonstration could not be determined. There is no primary evidence that Wells' demonstration occurred in the surgical amphitheater (Ether Dome) at Massachusetts General Hospital. Wells' demonstration of nitrous oxide probably occurred around the end of January 1845, in a public hall on Washington Street, Boston.
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Mild brain hypothermia (32°-34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase and an acetate uptake transporter. C nuclear magnetic resonance spectroscopy of rodent brain extracts after administering [1-C]glucose and [1,2-C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle entry via pyruvate dehydrogenase and pyruvate carboxylase. ⋯ Starting mild hypothermia simultaneously with oxygen-glucose deprivation, compared with delayed starting or no hypothermia, has higher pyruvate carboxylase throughput, suggesting that better glial integrity is one important neuroprotection mechanism of earlier hypothermia.
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Randomized Controlled Trial
Positive-end Expiratory Pressure Influences Echocardiographic Measures of Diastolic Function: A Randomized, Crossover Study in Cardiac Surgery Patients.
Ultrasonography of the cardiovascular system is pivotal for hemodynamic assessment. Diastolic function is evaluated with a combination of tissue Doppler (e' and a') and pulsed Doppler (E and A) measures of transmitral- and mitral valve annuli velocities. However, accurate echocardiographic evaluation in the intensive care unit or perioperative setting is contingent on relative resistance to positive pressure ventilation and changes in preload. This study aimed to evaluate the effects of positive end-expiratory pressure (PEEP) and positioning on echocardiographic measures of diastolic function. ⋯ When evaluating diastolic function by echocardiography, the levels of PEEP and its effect on ventricular area have to be taken into account. In addition, this study dissuades the use of E/e' for tracking changes in left ventricular filling pressures in cardiac surgery patients.
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Xenon, the inert anesthetic gas, is neuroprotective in models of brain injury. The authors investigate the neuroprotective mechanisms of the inert gases such as xenon, argon, krypton, neon, and helium in an in vitro model of traumatic brain injury. ⋯ Xenon neuroprotection against traumatic brain injury can be reversed by increasing the glycine concentration, consistent with inhibition at the N-methyl-D-aspartate receptor glycine site playing a significant role in xenon neuroprotection. Argon and xenon do not act via the same mechanism.