Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1996
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of solution concentration and epinephrine on lateral distribution of hyperbaric tetracaine spinal anesthesia.
In a search of a differential spinal block between dependent and nondependent sides, we investigated whether the use of a larger concentration of hyperbaric tetracaine (T) and/or the omission of epinephrine (E) would provide differential spread in patients left for 15 min in the lateral decubitus position. Spinal anesthesia was performed in the lateral decubitus position with the operated side dependent in 60 patients scheduled for lower limb surgery. All patients remained lateral for 15 min after spinal injection before being turned supine. ⋯ A comparable number of patients in all groups showed unilateral motor block: four in T 0.5% + E, two in T 1% + E, four in T 0.5%, and five in T 1%. Likewise, a comparable number of patients in all groups showed a prolonged duration of sensory and motor block, respectively: six and eight in T 0.5% + E, six and nine in T 1% + E, six and eight in T 0.5%, and seven and seven in T 1%. In conclusion, although a preferential distribution of hyperbaric T toward the dependent side in patients of all four groups was noticed, the use of a larger concentration of T, omission of E, or combination of these two factors did not provide a more marked differential spread when compared to the standard solution of T 0.5% + E.
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Anesthesia and analgesia · Oct 1996
The efficacy of axillary block for surgical procedures about the elbow.
Surgical procedures to the distal humerus, elbow, and proximal ulna and radius are ideally suited to regional techniques. However, axillary block is usually not recommended for surgery about the elbow because blockade at this level may result in inadequate block of the terminal nerves that arise from the medial, posterior, and lateral cords, and provide sensory innervation to the upper arm. This study reports the success rates for interscalene, supraclavicular, and axillary blocks for surgery about the elbow. ⋯ In addition, axillary blocks performed with mepivacaine had a higher success rate (93%) than those performed with bupivacaine (81%) (P < 0.01). There were no patients with perioperative respiratory compromise. These results demonstrate that the axillary approach to the brachial plexus may be successfully used for surgical procedures about the elbow.
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Anesthesia and analgesia · Oct 1996
ReviewPostoperative epidural opioid analgesia: what are the choices?
The administration of hydrophilic opioids via a continuous infusion results in selective spinal analgesia with a low incidence of side effects. Lipophilic opioids may also be associated with spinal effects. However, the doses required to produce postoperative analgesia also produce plasma concentrations within the MEAC. ⋯ Regardless of the mechanism of action, epidural administration of lipophilic opioids may offer no clinical advantages over the IV route. Notwithstanding, epidural administration of small doses of lipophilic opioids in combination with local anesthetics may offer significant clinical advantages over systemic administration of opioids alone. Dose-ranging studies will be necessary to determine the ideal concentrations of opioids and local anesthetics, as well as the ratios of the two drugs to obtain optimal analgesia with minimal incidence of side effects.
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Anesthesia and analgesia · Oct 1996
Randomized Controlled Trial Clinical TrialSpinal bupivacaine in ambulatory surgery: the effect of saline dilution.
The safety of lidocaine spinal anesthesia has recently been called into question by reports of both permanent and transient neurologic toxicity. This study explored the possibility of adapting the longer acting spinal bupivacaine to ambulatory surgery. Sixty patients presenting for ambulatory arthroscopy were randomized to four groups receiving the following spinal anesthetics: Group I (15 mg bupivacaine), 3 mL of 0.5% spinal bupivacaine in 8% dextrose; Group II (10 mg bupivacaine), 2 mL of the 0.5% spinal bupivacaine+1 mL saline; Group III (7.5 mg bupivacaine), 1.5 mL of the 0.5% spinal bupivacaine%1.5 mL saline; Group IV (5 mg bupivacaine), 1 mL of the 0.5% spinal bupivacaine+2 mL saline. ⋯ The intensity of sensory block also decreased from group to group with four patients in Group IV having pain intraoperatively that required further treatment. Therefore, Group III provided the optimum combination of adequate depth of anesthesia and rapid recovery. The results of this study indicate that spinal anesthesia with 7.5 mg of 0.5% bupivacaine in 8% dextrose diluted with an equal volume of saline provides an acceptable spinal anesthetic for ambulatory arthroscopy with a recovery profile appropriate to the ambulatory setting.
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Anesthesia and analgesia · Oct 1996
Comparative StudyA comparison of the local anesthetic effects of meperidine, fentanyl, and sufentanil on dorsal root axons.
The local anesthetic effects of opioids have been demonstrated in both clinical and laboratory studies. Clinically, both meperidine and sufentanil can produce segmental sensory anesthesia. However, previous studies of the effects of opioids on nerve conduction have all made use of peripheral nerve preparations and yielded conflicting results. ⋯ Fentanyl (0.6 microM and 3 microM) and sufentanil (1.04 microM) failed to affect the nerve conduction in any dorsal root axon. The discrepancy between laboratory and clinical observations is discussed. We suggest that the site of conduction block may occur at the proximal end of the dorsal root as it passes through the dorsal root entry zone, an anatomically unique segment of the primary sensory pathway with decreased conduction safety for action potential propagation.