Anesthesiology
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Comparative Study
Continuous noninvasive finger blood pressure during controlled hypotension. A comparison with intraarterial pressure.
The Finapres is a noninvasive monitor that continuously displays the arterial waveform, pulse rate, and systolic, mean, and diastolic blood pressure. We determined its bias (mean prediction error) and precision (mean absolute error), relative to directly measured radial arterial blood pressure, in 16 otherwise healthy patients undergoing spinal fusion surgery under hypotensive anesthetic techniques. Data were recorded during three contiguous epochs: 20 min of normotension; 30 min following the initiation of hypotension; 20 min of hypotension. ⋯ The Finapres closely tracked changes in blood pressure, even in the presence of a large bias. In most patients, the Finapres is a useful continuous noninvasive blood pressure monitor. Periodic calibration of the Finapres by the difference between Finapres and oscillometrically determined mean arterial pressure is recommended.
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The anatomic findings from cryomicrotome sections of 38 cadaver lumbar spines are reported. The technique produces high-resolution planar images of undisturbed epidural anatomy. Several observations differ from previous reports that used methods more prone to artifact. ⋯ The space anterior to the dura is filled with veins and is isolated from the rest of the epidural space by a membranous lateral extension of the posterior longitudinal ligament. This membrane and a midline posterior fat pedicle are the only observed potential barriers to the spread of epidural solutions. These findings may be important in understanding the mechanics and pharmacokinetics of solutions injected into the epidural space and in refining techniques for needle and catheter placement.
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Recent evidence suggests that edrophonium is not the agent of choice to reverse profound neuromuscular blockade but remains an efficacious drug when the level of neuromuscular blockade to be antagonized is modest. We studied 90 healthy adults in an attempt to address the questions: 1) How much variability in such neuromuscular parameters as single twitch height and the train-of-four (TOF) fade ratio (T4/T1) exist when the TOF count first returns to four palpable responses? 2) Is edrophonium a reliable antagonist at this measured point of recovery? 3) What is the optimal dose of edrophonium needed to produce prompt (less than 10 min) and satisfactory (T4/T1 greater than 0.7) reversal when the fourth response of the thumb to indirect TOF stimulation just becomes palpable? Patients were given a bolus atracurium or vecuronium (n = 45 in each group) followed by an iv infusion sufficient to maintain single twitch as measured by electromyography at 10-15% of control values. At the end of surgery, the infusion was terminated and spontaneous recovery was allowed to begin. ⋯ After atracurium neuromuscular blockade, edrophonium 0.3 mg/kg produced adequate antagonism in 10 min. At this time the mean T4/T1 ratio was 0.79 +/- 0.07 and the lowest observed value was 0.67. Increasing the edrophonium dose to 0.75 mg/kg accelerated recovery by 4-5 min.(ABSTRACT TRUNCATED AT 250 WORDS)