Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1994
Body position does not affect the hemodynamic response to venous air embolism in dogs.
Current therapy for massive venous air embolism (VAE) includes the use of the left lateral recumbent (LLR) position. This recommendation is based on animal studies, conducted 50 yr ago, which looked primarily at survival. Little is known, however, about the concomitant hemodynamic response after VAE in various body positions. ⋯ The acute hemodynamic changes occurring during the first 5-15 min after VAE recovered to 80% of control within 60 min. Our data suggest that body repositioning does not influence the cardiovascular response to VAE. Specifically, our data do not support the recommendation of repositioning into the LLR position for the treatment of VAE.
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Anesthesia and analgesia · Oct 1994
Comparative StudyIntracranial volume/pressure relationship during desflurane anesthesia in dogs: comparison with isoflurane and thiopental/halothane.
Desflurane-induced increase of intracranial pressure (ICP) does not appear to be completely explained by desflurane-induced changes in cerebral blood flow, cerebrospinal fluid (CSF) formation and reabsorption, or brain tissue water content. The present study was designed to determine whether desflurane alters intracranial volume/pressure relationships sufficiently to account for desflurane-induced increase of ICP. In 24 dogs, infusions of mock CSF were used to determine the CSF pressure increase due to increase of CSF volume, and the capacity of CSF pressure to return to baseline after a CSF pressure increase (CSF pressure normalization). ⋯ However, desflurane and isoflurane had no consistent effect on the other measures of CSF pressure increase caused by increase of CSF volume. Isoflurane also decreased the capacity for CSF pressure normalization at normal CSF pressure as indicated by decreased S1 and increased delta Ps. It is concluded that, under conditions of normal ICP, desflurane may decrease Ce, favoring an increase of ICP.
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Anesthesia and analgesia · Oct 1994
Comparative StudyProlonged analgesia and decreased toxicity with liposomal morphine in a mouse model.
Inadequate control of postoperative pain remains a major clinical problem. A reliable method of providing long-lasting postoperative analgesia with a single dose would be very useful. We synthesized a liposomal morphine formulation and compared it to free morphine with regard to duration of analgesia in the mouse. ⋯ In vitro experiments showed a slow release rate of morphine from the liposome depot. Prolonged analgesia and decreased systemic toxicity for liposomal morphine are explained by sustained release of morphine from the liposomal depot. These results suggest that liposomal narcotic formulations may provide prolonged analgesia with single-dose administration.
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Anesthesia and analgesia · Oct 1994
Comparative StudyComparison of the force required for dural puncture with different spinal needles and subsequent leakage of cerebrospinal fluid.
An in vitro model was used to determine the force required to pierce bovine dura with a range of new spinal needles and to measure the subsequent leakage rate of cerebrospinal fluid (CSF). A significantly greater force was required to pierce the dura with pencil-point style needles compared to Quincke needles of the same size. ⋯ The results suggest that there is not likely to be a significant reduction in postdural puncture headache (PDPH) using a 27-gauge pencil-point needle compared to a 25-gauge needle that may be easier to use. Different makes of the same design and gauge of needle showed significant differences in the amount of CSF leakage, which may influence the clinician's choice of needle.
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Anesthesia and analgesia · Oct 1994
The difference of isoflurane and halothane in ventriculoarterial coupling in dogs.
Effective arterial elastance (Ea) and left ventricular end-systolic elastance (Ees) are used as indices of cardiac afterload and cardiac contractility, respectively. We compared the effects of two volatile anesthetics, halothane and isoflurane, on ventriculoarterial coupling using an index of Ea/Ees in 20 mongrel dogs. Ees was obtained using a single-beat estimation technique. ⋯ The decreases in cardiac output and Ees were not significantly different between halothane and isoflurane. Halothane increased Ea/Ees from 0.83 +/- 0.05 to 1.22 +/- 0.13, whereas isoflurane maintained the Ees/Es at a constant level. Our results suggest that mechanical efficiency is well maintained during isoflurane anesthesia because it has an equivalent effect on left ventricular contractility and arterial properties, whereas halothane can impair mechanical efficiency by depressing left ventricular contractility more than the arterial system.