Articles: general-anesthesia.
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Comparative Study
The auditory evoked response as an indicator of awareness.
The latency of the early cortical wave Nb of the auditory evoked response (AER) was compared with responses to Tunstall's isolated forearm test, while the concentration of nitrous oxide was progressively reduced during light anaesthesia in seven patients. A threshold Nb latency of 44.5 ms was chosen to discriminate between an early cortical AER containing three waves and that with two waves of longer latency. ⋯ The addition of a volatile anaesthetic abolished any response, and increased Nb latency to more than 44.5 ms. The three wave AER pattern, therefore, is associated with a depth of anaesthesia at which awareness occurs.
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Randomized Controlled Trial Comparative Study Clinical Trial
Neuroleptanesthesia versus thoracic epidural anesthesia for abdominal aortic surgery.
The hemodynamic consequences of abdominal aortic surgery with infrarenal cross-clamping were studied in 21 patients randomized in two groups. In Group I (11 patients), neuroleptanesthesia was utilized, while Group II (10 patients) received thoracic epidural anesthesia at the T8-9 level. ⋯ Nevertheless, in the two groups of patients, it is suggested that cardiac function was unfitted to the tissue oxygen demand after unclamping of the aortic prosthesis because the saturation in oxygen of the mixed venous blood and an increase in arteriovenous difference in oxygen were documented. These results point out that, whatever the anesthesia technique, the critical period in abdominal surgery could be aortic unclamping.
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Current alarms protect the manufactures of medical equipment from liability but do little to improve the quality of patient care. Existing alarms are so intrusive that the response of the anesthesiologist and others in the operating room is to want the offensive noise to go away, rather than to address potentially life-threatening situations. Alarms need to be refined so that only those whose attention is required (e.g., the anesthesiologist) are disturbed. It should always be immediately clear which particular variable is outside accepted limits, and alarms for different variables should operate independently so that if one alarm fails, others will still work.
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The administration of anesthesia may be viewed as a closed-loop control system consisting of three major components: the anesthesia system, the patient, and the system operator. A monitoring and alarm system during anesthesia should not be limited to only one of the three major components but must include monitoring of the patient, the performance of the anesthesia system, and the action of the system operator. ⋯ The authors describe the characteristics of a structured alarm system that maximizes the time available to correct a potential problem before injury begins, that clearly identifies the cause of the problem, and that prioritizes alarms according to the urgency of the required response. Alarms should be easy to temporarily silence, have built-in alarm default settings to prevent the inadvertant use of settings meant for a previous patient, and have a graphic display that enables the operator to detect problems or trends before an alarm sounds.