Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1989
Clinical Trial Controlled Clinical TrialEffect of injection rate on level and duration of hypobaric spinal anesthesia.
The purpose of this study was to determine whether injection rate affects the spread of hypobaric spinal anesthesia. Hypobaric spinal anesthesia was performed on 20 patients for total hip arthroplasty. Dural puncture was performed with a 22-gauge Whitacre needle. ⋯ Four-segment regression of anesthetic levels took significantly longer in the slow injection group. Local anesthetic mixtures used were consistently hypobaric compared to patient CSF. We conclude that slow injection of hypobaric tetracaine through a 22-gauge Whitacre needle produces lower levels of spinal anesthesia that tend to be of longer duration than levels resulting from fast injection.
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Using a new in vitro model and samples of human dura, a number of factors related to spinal needle design and use were examined with respect to their effects on the rate of transdural fluid leak. These included needle size, bevel design, bevel orientation, and angle of approach. ⋯ Also, 22-gauge Whitacre needles caused significantly less leak than did 22-gauge Quincke needles, and 25-gauge Quincke needles produced significantly less leak than 22-gauge Quincke needles. If human dura behaves in vivo as it does in this in vitro model, it would be advantageous to perform lumbar puncture using oblique approaches and small needles with conical tips.
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Anesthesia and analgesia · Oct 1989
Malignant hyperthermia in humans--standardization of contracture testing protocol.
Malignant hyperthermia (MH) diagnostic biopsy centers across North America have not previously been standardized in regard to protocols and specific muscles. Recent standardization criteria prompted this study of the vastus and rectus abdominis muscles. This study evaluated changes in contracture tension after electrical stimulation of 271 bundles taken from the vastus (n = 16) and rectus abdominus (n = 19) muscle biopsies of normal individuals when exposed to tissue baths in the absence of and in the presence of caffeine (0.5, 1.0, 2.0, 4.0, 8.0, and 32.0 mM) alone, halothane (1% or 3%) alone, or the combination of halothane (1%) plus caffeine (0.25, 0.5, 1.0, 2.0, 4.0, and 32.0). ⋯ Caffeine specific concentration was significantly greater for vastus muscle (7.7 +/- 0.7 mM) than it was for rectus muscle (4.9 +/- 0.4 mM). Three percent halothane alone showed contractures in 3/41 vastus (all less than 0.5 g) and 18/54 rectus muscle bundles (8 greater than 0.5 g). Mean HCSC was statistically significantly greater for vastus muscle (1.9 +/- 0.2 mM) than for rectus muscle (1.2 +/- 0.2 mM).(ABSTRACT TRUNCATED AT 250 WORDS)