Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Core hypothermia and skin-surface temperature gradients. Epidural versus general anesthesia and the effects of age.
Inadvertent hypothermia occurs frequently during surgery and may be associated with adverse outcomes. Although various anesthetic agents have been shown to impair thermoregulation, the impairment with regional and general anesthetics has not been directly compared. ⋯ The EA and GA groups had virtually identical core temperature profiles during the intraoperative and post-operative periods. Comparison of skin-surface gradients suggests that EA is associated with less intraoperative upper-body thermoregulatory impairment but greater and persistent post-operative lower-body impairment. During EA, younger patients appeared to maintain thermoregulatory activity relative to the older patients. In patients receiving GA, the age-related differences were minimal.
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Randomized Controlled Trial Comparative Study Clinical Trial
Midlatency auditory evoked potentials and explicit and implicit memory in patients undergoing cardiac surgery.
A high incidence of intraoperative awareness during cardiac surgery has been reported. Midlatency auditory evoked potentials (MLAEP) have been used recently as an indicator of awareness. In the current study, memory for information presented during anesthesia was investigated using MLAEP as one experimental indicator in 45 patients scheduled for elective cardiac surgery. ⋯ When the early cortical potentials of MLAEP are preserved during general anesthesia, auditory information may be processed and remembered postoperatively by an implicit memory task.
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Randomized Controlled Trial Comparative Study Clinical Trial
The laryngeal mask airway and positive-pressure ventilation.
The utility of the laryngeal mask airway during positive-pressure ventilation has yet to be determined. Our study was designed to assess whether significant leaks occurred with positive-pressure ventilation and if leaks were associated with gastroesophageal insufflation. ⋯ Ventilation using the laryngeal mask appears to be adequate if airway resistance and pulmonary compliance are normal. Gastroesophageal insufflation of air will become a problem in the presence increased ventilation pressure.
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Randomized Controlled Trial Clinical Trial
Humans anesthetized with sevoflurane or isoflurane have similar arrhythmic response to epinephrine.
Anesthetics can alter the dose of exogenously administered epinephrine that causes cardiac arrhythmias. The purpose of this study was to test the hypothesis that in humans anesthetized with sevoflurane, the arrhythmic response to epinephrine is not different from the response in humans anesthetized with isoflurane. ⋯ Sevoflurane and isoflurane do not differ in their sensitization of the human myocardium to the arrhythmogenic effect of exogenously administered epinephrine.
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Impaired gas exchange is a major complication after cardiac surgery with the use of extracorporeal circulation. Blood gas analysis gives little information on underlying mechanisms, in particular if the impairment is multifactorial. In the current study we used the multiple inert gas technique with recordings of hemodynamics to analyze the separate effects of intrapulmonary shunt (QS/QT), ventilation-perfusion (VA/Q) mismatch, and low mixed venous oxygen tension on arterial oxygenation during cardiac surgery. ⋯ QS/QT is a major component of impaired gas exchange before, during, and after cardiac surgery. QS/QT increases after induction of general anesthesia, probably because of development of atelectasis. After separation from extracorporeal circulation, accumulation of extravascular lung water or further collapse of lung tissue may aggravate QS/QT. Postoperatively, oxygenation improves, possibly because of recruitment of previously nonventilated alveoli or resolution of extravascular lung water. During spontaneous breathing, additional mechanisms such as altered mechanics of the chest, perfusion of low-VA/Q regions, and decreased mixed venous oxygen tension may contribute to impaired gas exchange.