Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2011
Case ReportsThe possible influence of pulmonary arterio-venous shunt and hypoxic pulmonary vasoconstriction on arterial sevoflurane concentration during one-lung ventilation.
Sevoflurane is widely used for its rapid onset and offset due to a lower blood/gas coefficient. However, involuntary movements, tachycardia, and hypertension have been observed in some patients despite a continuing constantly delivered concentration of sevoflurane during 1-lung ventilation (OLV), indicating the possibility of insufficient depth of anesthesia. We observed a temporary but obvious decrease in arterial sevoflurane concentration and pulse oximeter readings in a patient during OLV. This may have resulted in the depth of inhaled anesthesia being insufficient during OLV because the arterial sevoflurane concentration was lower than expected in spite of constantly delivered and inspiratory/expiratory sevoflurane concentrations.
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Anesthesia and analgesia · Feb 2011
Comparative StudyHistological analysis after peripheral nerve puncture with pencil-point or Tuohy needletip.
Continuous peripheral nerve blocks typically are performed with a "through-the-needle technique" and require needles with an inner diameter allowing catheter placement. In case of direct needle-nerve contact, the pencil-point needletip is currently considered less traumatic than are other needle configurations. In this study we determined whether nerve puncture with pencil-point needles is associated with fewer nerve injuries in comparison with Tuohy needles. ⋯ Regardless of the needletip configuration applied for nerve puncture, pencil-point and Tuohy needletips may both lead to comparable magnitude of posttraumatic inflammation and considerable structural changes within the nerve. No significant differences were found comparing pencil-point with Tuohy tip-configured needles.
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Anesthesia and analgesia · Feb 2011
Pulse oximeter plethysmographic waveform changes in awake, spontaneously breathing, hypovolemic volunteers.
The primary objective of this study was to determine whether alterations in the pulse oximeter waveform characteristics would track progressive reductions in central blood volume. We also assessed whether changes in the pulse oximeter waveform provide an indication of blood loss in the hemorrhaging patient before changes in standard vital signs. ⋯ These results support the use of pulse oximeter waveform analysis as a potential diagnostic tool to detect clinically significant hypovolemia before the onset of cardiovascular decompensation in spontaneously breathing patients.
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Perception of turnovers may be influenced less by actual turnover times per se than by a mental model of factors influencing turnover times. ⋯ Managers should not rely on surgeons or anesthesiologists for their expert judgment on turnover times. Managers should also not interpret comments about turnover times as literally referring to the time, but instead as factors perceived as contributing to the time (e.g., attitude about the facility and the activity of its personnel).
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Anesthesia and analgesia · Feb 2011
Reinforcement learning: a novel method for optimal control of propofol-induced hypnosis.
Reinforcement learning (RL) is an intelligent systems technique with a history of success in difficult robotic control problems. Similar machine learning techniques, such as artificial neural networks and fuzzy logic, have been successfully applied to clinical control problems. Although RL presents a mathematically robust method of achieving optimal control in systems challenged with noise, nonlinearity, time delay, and uncertainty, no application of RL in clinical anesthesia has been reported.