Regional anesthesia
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Regional anesthesia · May 1989
Epidural morphine anesthesia for abdominal aortic surgery--pharmacokinetics.
Plasma and CSF pharmacokinetics of morphine given epidurally in combination with general anesthesia for abdominal aortic surgery were recorded. The initial plasma and CSF concentrations of morphine appeared at two minutes. The peak plasma concentrations of morphine were recorded at 8.0 +/- 2.6 minutes after epidural injection. ⋯ MRT (200 +/- 28 minute), Vdss (65 +/- 33.8 ml), and CL (0.32 +/- 0.15 ml/min) showed that variable fractions of morphine remained many hours in the CSF. Factors that could produce the interindividual variability of plasma and CSF concentrations and pharmacokinetics of epidural morphine were discussed. Abdominal aortic surgery appears to influence both plasma and CSF pharmacokinetics.
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Regional anesthesia · Mar 1989
A two-person technique for epidural needle placement and medication infusion.
Traditional techniques of epidural needle placement have not proved satisfactory in patients who have had a previous laminectomy and may have epiduroarachnoiditis. A two-person technique was developed to: 1) simplify performance of difficult, epidural needle placement; 2) allow both resident and staff a simultaneous "hands-on" teaching experience; 3) allow a painless method of medication administration in patients with altered epidural anatomy; and 4) allow a simple method for determination of epidural space pressures. A glass syringe and extension tubing filled with saline are connected to the epidural needle. ⋯ The column of saline falls and fluctuates with heart beat, providing verification of correct needle placement. Medication is placed in the barrel of the syringe and allowed to infuse by gravity. The two-person technique has achieved both patient and resident acceptance, and allows a painless method of medication administration in patients with altered epidural space anatomy.
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Regional anesthesia · Mar 1989
Contractility effects of local anesthetics in the presence of sodium channel blockade.
The effects of lidocaine (25, 50 and 100 micrograms/ml) and bupivacaine (5, 10, and 20 micrograms/ml) on amplitude, velocity, and contraction frequency were studied in monolayer cultures of spontaneously beating chick embryo ventricular cells. The physiologic parameters of contraction frequency, amplitude, and velocity of shortening were measured with an optical-video system. Studies were also carried out in the presence of 1 microM tetrodotoxin (TTX) to isolate effects caused by TTX-sensitive ion channel blockade from other possible mechanisms of action of local anesthetics. ⋯ In the presence of TTX, lidocaine (50 micrograms/ml) produced a further decrease in amplitude of contraction, but no significant change in contraction frequency or velocity of contraction. It is well known that local anesthetics block Na+ channels of excitable membranes. The authors observations suggest that both lidocaine and bupivacaine have at least one locus of action at a site other than a TTX blockade site.