Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1993
Randomized Controlled Trial Clinical TrialOnset, intensity of blockade and somatosensory evoked potential changes of the lumbosacral dermatomes after epidural anesthesia with alkalinized lidocaine.
The onset and intensity of blockade of the lumbosacral dermatomes after epidural anesthesia with alkalinized lidocaine were investigated in a randomized, double-blind study in 26 patients. Control subjects (n = 13) received 20 mL of 1.37% lidocaine (1.5% lidocaine plus 1 mL saline per 10 mL lidocaine) with added 1:200,000 epinephrine; the solution pH was 6.20 +/- 0.08. Patients in the alkalinized lidocaine group (n = 13) were given 20 mL of 1.37% lidocaine plus added bicarbonate (1 mL sodium bicarbonate per 10 mL 1.5% lidocaine) and 1:200,000 epinephrine; the solution pH was 7.18 +/- 0.10. ⋯ Motor blockade was significantly more profound in the alkalinized lidocaine group. Thirteen of 78 PTN and L5 and S1 dermatomal SSEPs were abolished in the alkalinized lidocaine group compared to 4 of 78 SSEPs in the nonalkalinized group. Alkalinization of lidocaine is recommended to shorten the time to block the L5-S1 dermatomes when epidural anesthesia is planned for lower extremity surgery.
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Anesthesia and analgesia · Feb 1993
Influence of age on awakening concentrations of sevoflurane and isoflurane.
We determined whether age, duration of anesthesia, gender, or type of surgery significantly influenced end-tidal concentrations on awakening from anesthesia with sevoflurane and isoflurane in 39 healthy ASA physical status I patients. Postoperatively, the end-tidal anesthetic concentration was maintained at a constant level at least for 15 min. If patients failed to open their eyes on request, the end-tidal concentration was decreased and again maintained at a constant level for 15 min. ⋯ The end-tidal concentrations on awakening from anesthesia were 0.62 +/- 0.02% (mean +/- SE) for sevoflurane and 0.41 +/- 0.02% for isoflurane. Awakening concentration of sevoflurane and isoflurane correlated significantly with age (P < 0.001), but not with duration of anesthesia, gender, or type of surgery. The authors conclude that awakening concentration decreases at the similar rate of decrease in minimum alveolar concentration (MAC) with increasing age; and therefore, the ratios to MAC are fairly constant, being 0.34 for both sevoflurane and isoflurane.
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Vigilance is an important but difficult to measure attribute in anesthesia practitioners. We present a modified standard method to assess intraoperative vigilance toward electronic data displays. The response time to detect a simulated abnormal value on the physiologic monitor was measured. ⋯ Response times and the rate of missed events were greater during induction of anesthesia (a time of high workload) than during the maintenance or emergence phases of anesthesia. Response times were shorter during procedures on ASA 1 patients than on ASA 3 patients. The results suggest that anesthesiologists usually quickly detect abnormal values on physiologic monitors and that less attention is devoted to monitors during periods of high workload.