Regional anesthesia
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Regional anesthesia · Sep 1991
Popliteal sciatic nerve block aided by a nerve stimulator: a reliable technique for foot and ankle surgery.
The reliability of popliteal sciatic nerve blocks was prospectively assessed in 625 blocks performed in 507 patients. The sciatic nerve was approached at the apex of the popliteal fossa, in the midline, with an insulated needle connected to a peripheral nerve stimulator partially designed by one of the authors. When needed, an inguinal paravascular femoral nerve block was also performed. ⋯ Overall satisfaction with perioperative analgesia was evaluated by 466 patients: 444 (95%) were completely satisfied, 20 (4%) expressed moderate reservations and two (1%) expressed major reservations. The authors conclude that the technique is a safe and reliable alternative to more common forms of anesthesia for surgery below the knee. They attribute the great success rate to a high popliteal approach, the use of insulated needles, a discriminating mode of nerve stimulation and the systematic search for optimal response to needle stimulation.
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Regional anesthesia · Sep 1991
Case ReportsBlood pressure, not heart rate, as a marker of intravascular injection of epinephrine in an epidural test dose.
Investigators have generally examined the heart rate response after injection of a test dose containing a beta-adrenergic agonist as an indicator of intravascular placement of an epidural catheter. Some have reported an increase in blood pressure accompanying the increase in heart rate after an intravascular injection. ⋯ As far as we know, this phenomenon previously has been described only in patients receiving beta-adrenergic blocking drugs. In these patients it may be related to decreased beta-adrenergic receptor responsiveness in elderly patients; this and other possible mechanisms are discussed.
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Regional anesthesia · Sep 1991
Case ReportsPost dural puncture headache after lumbar sympathetic block: a report of two cases.
Dural puncture during lumbar sympathetic block (LSB) is a recognized but apparently uncommon complication. Interestingly, post dural puncture headache (PDPH) has not been reported as a complication of LSB. ⋯ In the second case the patient developed PDPH and a subdural block during separate LSBs. Possible anatomic explanations for these complications are discussed.
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Twenty consecutive patients requiring surgical procedures on a lower extremity received leg blocks using a modification of Labat's classic approach. A Doppler ultrasound pencil probe was used to identify the dominant arterial structure exiting the sciatic notch with the sciatic nerve. A block needle was inserted in the same orientation as the probe until paraesthesias were elicited; then 25 ml of local anesthetic was injected. Successful block was achieved in one or two attempts in 70% of the patients.
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The influence of digoxin on the systemic toxic effects of bupivacaine was studied in a rodent animal model. The experiment was undertaken with consideration to clinical situations such as pregnancy that are associated with the secretion of an endogenous digoxin-like factor. Twenty Wistar male rats, under barbiturate anesthesia and controlled ventilation, received either 5 micrograms/kg intravenous digoxin (n = 10) or saline (n = 10), blinded to the observer. ⋯ The threshold doses of bupivacaine toxic effects (first ventricular arrhythmia, 25% fall of baseline heart rate, 25% fall of baseline mean arterial blood pressure, first seizure activity, isoelectric electroencephalogram, and asystole) were significantly lower in the digoxin group, as were the lethal bupivacaine serum concentrations. Digoxin, in hyperoxic nonacidotic rats, increases the cardiac and central nervous system toxicity of bupivacaine. Based on the known electrophysiologic actions of these two drugs, a synergistic toxic interaction is demonstrated.