Regional anesthesia
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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.
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Regional anesthesia · Sep 1991
Randomized Controlled Trial Clinical TrialEpidural butorphanol augments lidocaine sensory anesthesia during labor.
To determine the efficacy and safety of epidural butorphanol combined with lidocaine, 50 healthy parturients were studied during labor and delivery. All patients received a test dose of 3 ml 1.5% lidocaine with 1:200,000 epinephrine. Patients were then randomly assigned to receive 7 ml of one of two epidural regimens in a double-blind fashion: Group 1 patients received 1.5% lidocaine plus 1 mg butorphanol plus 1:300,000 epinephrine; Group 2 patients received 1.5% lidocaine plus 1:300,000 epinephrine. ⋯ There were no difference between groups in duration of first and second stages of labor, method of delivery or neonatal outcome. Umbilical cord acid-base status and neurologic adaptive capacity scores did not differ significantly between the two groups. The authors conclude that adding small doses of butorphanol to epidural lidocaine during labor is effective and safe.