Anesthesiology
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Comment Letter Biography Historical Article
Henry Ruth and history: his rightful place?
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The pupillary light reflex often is evaluated in the perianesthetic period to assess drug effects and brainstem function. Mild hypothermia alone or combined with isoflurane does not impair pupillary responses. Although perioperative hyperthermia is less common than hypothermia, abnormal increases in core temperature remain an important thermal disturbance. Accordingly, the pupillary effects of hyperthermia alone and hyperthermia combined with isoflurane and enflurane were evaluated. Additionally, the effects of nitrous oxide on pupillary responses were determined. ⋯ Anesthetic-induced inhibition of the pupillary response to light is reversed partially by core hyperthermia. In contrast to enflurane and isoflurane, 60% N2O has little effect on the pupil.
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Comparative Study Clinical Trial
Intraoperative transesophageal echocardiography for the detection of cardiac preload changes induced by transfusion and phlebotomy in pediatric patients.
Intraoperative blood volume changes are difficult to monitor in pediatric patients. The authors tested the hypothesis that transesophageal echocardiography would identify changes in cardiac filling resulting from manipulations of blood volume. ⋯ Transesophageal echocardiography is a potentially useful monitor of cardiac filling changes in pediatric patients.
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Case Reports
False-negative results with muscle caffeine halothane contracture testing for malignant hyperthermia.
During the period 1985-1991, 350 muscle contracture studies have been performed in the authors' laboratory, and during this period, they became aware of an occasional false-negative result. The findings pertaining to the four cases so classified are presented in detail. ⋯ This study documents the rarity of false-negative results and substantiates the reliability of caffeine halothane testing as a biologic test in diagnosing the presence of a potentially serious problem.
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Hemodilution (HD) with oxyhemoglobin colloid (oxyHb) provides a greater arterial oxygen content (CaO2) than HD with conventional colloids; however, oxygen delivery (DO2) is essentially the same, because, in contrast to conventional HD, cardiac output (CO) is not augmented. This study seeks to elucidate the mechanism that limits CO during oxyHb-HD and to test whether infusion of a nitric oxide (NO) donor would augment DO2, because oxyHb is known to inactivate in vitro endothelial-derived NO. ⋯ This study indicates that the limited CO and DO2 of oxyHb-HD resulted from opposing changes in two determinants of flow, i.e., reduced blood viscosity and increased arterial resistance (vasoconstriction). The vasoconstriction was not evident with metHb-HD and was reversed by the SNP infusion, indicating that oxyHb inactivated in vivo endothelial-derived NO. The ability of the NO donor (SNP) to facilitate large viscosity-mediated increases in DO2 during oxyHb-HD is an important finding that could potentially render oxyHb colloids more useful than conventional colloids, particularly for the individual with a compromised circulation who would benefit from an increased oxygen supply.