Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Is combined spinal-epidural analgesia associated with more rapid cervical dilation in nulliparous patients when compared with conventional epidural analgesia?
The combined spinal-epidural technique provides rapid onset of labor analgesia and, anecdotally, is associated with labors of shorter duration. Epidural analgesia, by contrast, has been suggested to prolong labor modestly. It is unclear, however, whether more rapid cervical dilation in patients who receive combined spinal-epidural analgesia is a physiologic effect of the technique or an artifact of patient selection. The authors hypothesized that anesthetic technique may influence the rate of cervical dilation, and we compared the effects of combined spinalepidural with those of epidural analgesia on the rate of cervical dilation. ⋯ In healthy nulliparous parturients in early labor, combined spinal-epidural analgesia is associated with more rapid cervical dilation compared with epidural analgesia. Further study is needed to elicit the cause and overall effect of this difference.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparable postoperative pulmonary atelectasis in patients given 30% or 80% oxygen during and 2 hours after colon resection.
High concentrations of inspired oxygen are associated with pulmonary atelectasis but also provide recognized advantages. Consequently, the appropriate inspired oxygen concentration for general surgical use remains controversial. The authors tested the hypothesis that atelectasis and pulmonary dysfunction on the first postoperative day are comparable in patients given 30% or 80% perioperative oxygen. ⋯ Lung volumes, the incidence and severity of atelectasis, and alveolar gas exchange were comparable in patients given 30% and 80% perioperative oxygen. The authors conclude that administration of 80% oxygen in the perioperative period does not worsen lung function. Therefore, patients who may benefit from generous oxygen partial pressures should not be denied supplemental perioperative oxygen for fear of causing atelectasis.
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Randomized Controlled Trial Comparative Study Clinical Trial
Postoperative pain facilitates nonthermoregulatory tremor.
Spontaneous tremor is relatively common in normothermic patients after operation and has been attributed to many causes. The hypothesis that nonthermoregulatory shivering-like tremor is facilitated by postoperative pain was tested. In addition, the effects of intravenous lidocaine on nonthermoregulatory tremor were evaluated. ⋯ Intra-articular, but not intravenous, lidocaine reduced surgical pain and prevented nonthermoregulatory shivering. Therefore, these data indicate that postoperative pain facilitates nonthermoregulatory shivering.
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Randomized Controlled Trial Clinical Trial
Effect of epinephrine on lidocaine clearance in vivo: a microdialysis study in humans.
Local anesthetic nerve block prolonged by epinephrine is thought to result from local vasoconstriction and consequent decreased local anesthetic clearance from the injection site. However, no study has yet confirmed this directly in humans by measuring tissue concentrations of local anesthetic over time. In addition, recent studies have shown that the alpha2-adrenergic receptor agonist, clonidine, also prolongs nerve block without altering local anesthetic clearance. Because epinephrine is also an alpha2-adrenergic receptor agonist, it is possible that epinephrine prolongs local anesthetic block by a pharmacodynamic mechanism and not a pharmacokinetic one. This study was designed to address this issue. ⋯ Although epinephrine activates alpha2-adrenergic receptors, its mechanism for prolonging the duration of local anesthetic block rests on its ability to decrease local anesthetic clearance and not on a pharmacodynamically mediated potentiation of local anesthetic effect.
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Comparative Study Clinical Trial
Correlation between cerebral oxygen saturation measured by near-infrared spectroscopy and jugular oxygen saturation in patients with severe closed head injury.
Near-infrared spectroscopy has been used to monitor cerebral oxygen saturation during cerebral circulatory arrest and carotid clamping. However, its utility has not been demonstrated in more complex situations, such as in patients with head injuries. The authors tested this method during conditions that may alter the arteriovenous partition of cerebral blood in different ways. ⋯ Cerebral oxygen saturation assessed by near-infrared spectroscopy does not adequately reflect changes in jugular venous oxygen saturation in patients with severe head injury. Changes in arteriovenous partitioning, infrared-spectroscopy contamination by extracerebral signal, algorithm errors, and dissimilar tissue sampling may explain these findings.