Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Continuous infusion epidural analgesia during labor: a randomized, double-blind comparison of 0.0625% bupivacaine/0.0002% fentanyl versus 0.125% bupivacaine.
The analgesic efficacy of the continuous epidural infusion of 0.0625% bupivacaine/0.0002% fentanyl was compared with the infusion of 0.125% bupivacaine alone in a randomized, double-blind study of nulliparous women. Each patient received, in sequence: 1) 3 ml of 0.5% bupivacaine with 1:200,000 epinephrine; 2) 6 ml of study solution 1 (bupivacaine-fentanyl group: 0.125% bupivacaine/0.0008% fentanyl; bupivacaine-only group: 0.25% bupivacaine alone); and 3) a continuous epidural infusion of study solution 2 at a rate of 12.5 ml/h (bupivacaine-fentanyl group: 0.0625% bupivacaine/0.0002% fentanyl; bupivacaine-only group: 0.125% bupivacaine alone). The epidural infusion was discontinued at full cervical dilatation, but patients who lacked perineal anesthesia received one or two 5-ml boluses of study solution 3 (bupivacaine-fentanyl group: 0.0625% bupivacaine alone; bupivacaine-only group: 0.125% bupivacaine alone). ⋯ During the second stage, 22 of 37 (59%) women in the bupivacaine-fentanyl group, and 23 of 35 (66%) women in the bupivacaine-only group, rated their analgesia as excellent or good (P = NS). Women in the bupivacaine-only group were more likely to have motor block at full cervical dilatation (P less than .001). There was no significant difference between groups in duration of the second stage of labor, duration of pushing, position of the vertex before delivery, method of delivery, Apgar scores, or umbilical cord blood gas and acid-base values.(ABSTRACT TRUNCATED AT 250 WORDS)
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Histamine is released during allergic reactions, and is known to produce cardiac dysrhythmias. The authors compared the cardiac effects of histamine and epinephrine during exposure to halothane in the isolated perfused guinea pig heart. Responses studied were spontaneous sinus rate, intra-atrial conduction time, atrial-septal conduction time (ASCT), intraventricular conduction time (IVCT), and left ventricular pressure (LVP). ⋯ Halothane antagonizes the inotropic and chronotropic effects of epinephrine, but increases the incidence of ventricular tachycardia from 6% to 28%, and the incidence of premature ventricular excitations from 0% to 40%, compared with epinephrine alone. The authors' in vitro findings show that histamine and halothane, like epinephrine and halothane, can cause dysrhythmias, but that the genesis and type of dysrhythmias induced by these agents are dissimilar. Consequently, the release of histamine with an anaphylactoid reaction during halothane anesthesia, and the treatment of the reaction with epinephrine, could result in dangerous ventricular tachydysrhythmias.
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Mivacurium chloride (BW B1090U), a bis-benzylisoquinolinium diester compound, was found to undergo hydrolysis in vitro by purified human plasma cholinesterase in a pH-stat titrator at 88% of the rate of succinylcholine at pH 7.4, 37 degrees C and 5 microM substrate concentration. In 72 consenting ASA Physical Status I-II patients receiving nitrous oxide/oxygen-narcotic-thiopental anesthesia, the neuromuscular blocking effect of mivacurium was assessed following bolus doses from 0.03 to 0.30 mg/kg, as well as during and following continuous infusions from 35 to 324 min in length. The calculated ED95 for inhibition of adductor pollicis twitch evoked at 0.15 Hz was 0.08 mg/kg. ⋯ Twitch returned to 95% of control within 4.5 to 9.5 (6.3 +/- 0.5) min after neostigmine. Mivacurium may offer increased versatility in providing clinical muscle relaxation in a variety of situations. Further studies seem appropriate.
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Randomized Controlled Trial Comparative Study Clinical Trial
Anesthesia for ophthalmic surgery in the elderly: the effects of clonidine on intraocular pressure, perioperative hemodynamics, and anesthetic requirement.
The effects of clonidine on intraocular pressure and perioperative cardiovascular variables were studied by a randomized double blind design in 80 elderly patients (ASA physical status I-III) scheduled for elective ophthalmic surgery under general anesthesia (GA) and local anesthesia (LA). Group 1 (n = 40), the control group, received diazepam po (0.1 mg.kg-1) 90-120 min prior to arrival to the operating room. Group 2 (n = 40) received clonidine po approximately 5 micrograms.kg-1 po at the same time. ⋯ Intraoperatively, a significantly higher incidence of hypertension (P less than 0.01) and tachycardia (P less than 0.05) were respectively observed in the LA subset and GA subset of the controls when contrasted with the corresponding subset of those receiving clonidine. Moreover, clonidine was more effective than diazepam as a premedication; in fact, satisfactory intraoperative sedation and cardiovascular stability were observed in 85% of the patients who received clonidine, and in 50% of those patients who did not receive clonidine (P less than 0.01). Thus, clonidine may represent a useful adjunct in the management of the aged patient in the setting of ophthalmic surgery.