Masui. The Japanese journal of anesthesiology
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Pain on injection is one of the well-known side effects of propofol. Previous studies have shown several methods to alleviate this discomfort. We employed all these methods together to clarity whether pain-free injection of propofol was possible. ⋯ Eighteen patients (90%) in the control group experienced injection pain. In the study group, however, no patients complained of pain or discomfort. In conclusion, pain-free injection of propofol was possible when prior-administration of fentanyl, premixing of lidocaine, cooling to 4 degrees C, and rapid injection via a forearm vein without carrier i.v. fluid was the adopted precedure.
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We studied the neurotoxic effect of lidocaine at different concentrations on the desheathed rabbit vagus nerve by measuring the amplitudes of evoked compound action potentials and the histological changes of the nerve by means of the electron microscopy after incubation in lidocaine-Ringer's bicarbonate (RB) solution. The following results were obtained. 1) Minimum concentrations of lidocaine for producing complete conduction block (minimum blocking concentration, MBC) were 0.02% for A beta and A delta fibers, and 0.03% for C fibers. 2) Irreversible conduction blocks of compound action potentials were observed in relation with lidocaine concentrations and the duration of incubation: e.g. 0.5% for 2 hours incubation was equivalent to the block with 1% for 1 hour. 3) Degenerative change of axons was revealed morphologically in the preparations exposed to 2% or a higher concentration of lidocaine. 4) Risk ratio, which means a numerical value calculated as clinical concentration/irreversible concentration with 2 hr exposure, was similar to other local anesthetics except dibucaine HCl, which shows an higher risk ratio. However, it should be noted that lidocaine has an risk of producing irreversible changes in nerve fibers, when applied to the nervous tissue at higher concentrations for longer durations.
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Randomized Controlled Trial Clinical Trial
[Sixty percent lidocaine tape alleviates pain on injection of propofol after diminishing venipuncture pain].
We evaluated the efficacy of the 60% lidocaine tape in alleviating pain associated with intravenous propofol administration in 71 gynecological patients. Thirty-eight women had the tape applied for 2.5 h before venipuncture, with the remaining patients acting as the control. A 20 gauge cannula was inserted into the cephalic vein. ⋯ Moreover, the pain intensity was decreased with lidocaine tape (P = 0.006). The cost of the lidocaine tape is covered by medical insurance for reducing pain on venipuncture. Thus, as the tape also alleviates the pain on injection of propofol through its anesthetic action, it can be a safe, easy and cost-effective method as "it kills two pains with one tape".
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Comparative Study Clinical Trial
[Comparative effect of tranexamic acid on the reduction of bleeding during and after cardiac surgery].
The administration of tranexamic acid (TA), an antifibrinolytic agent, prior to cardiopulmonary bypass (CPB) has been reported to reduce bleeding after cardiac surgery. In a retrospective clinical trial, 99 adults patients undergoing open heart surgery received TA (CABG, TA (+): n = 20; Valve replacement, TA (+): n = 20) or did not receive TA (CABG, TA (-): n = 20: Valve replacement, TA (-): n = 19). In the TA group, just after induction of general anesthesia, a 160 mg.kg-1 dose of TA was administered intravenously. ⋯ Patients of [CABG, TA (+)] group had significantly less intraoperative and total blood loss [total blood loss 608 g : 313 g, intraoperatively, 134 g at 6 hours, and 296 g at 24 hours] compared with [CABG, TA (-)] group (total blood loss 1043 g: 640 g, intraoperatively, 232 g at 6 hours, and 403 g at 24 hours). Additionally, in patients of Valve replacement, TA (+) group had less but not significant total blood loss (total blood loss 903 g: 523 g, intraoperatively, 173 g at 6 hours, and 380 g at 24 hours) compared with TA (-) group (total blood loss 1237 g: 863 g, intraoperatively, 214 g at 6 hours, and 374 g at 24 hours). TA administered prior to CPB may reduce the amount of bleeding during and after cardiac surgery.
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Comparative Study
[Comparison of the vascular effects of propofol and those of thiopental in patients under cardiopulmonary bypass].
The effects of propofol (1 mg.kg-1) and thiopental (2.5 mg.kg-1) on the vascular smooth muscle were investigated in 10 cardiac patients on cardiopulmonary total bypass using a constant perfusion flow. Radial mean arterial blood pressure (mAP) decreased to 85 +/- 5% (P < 0.01, vs preinjection) in the post-injection late phase (2-3 min) after propofol, and to 90 +/- 6% (P < 0.01) after thiopental. MAP after thiopental showed a transient initial increase to 115 +/- 8% (P < 0.01) in the post-injection early phase (-1 min). ⋯ The increase in SBF after propofol was greater than that after thiopental (P < 0.05). The decrease in mAP and the increase in SBF under the constant perfusion flow are considered mainly due to a direct drug action of dilating peripheral vessels. In conclusion, this in vivo human study suggests that propofol (1 mg.kg-1) causes more potent vasodilatation in the peripheral vessels than thiopental (2.5 mg.kg-1).