Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · Oct 1988
Randomized Controlled Trial Clinical TrialLower limb compression using inflatable splints to prevent hypotension during spinal anaesthesia for caesarean section.
The efficacy of pneumatic compression of the lower limbs using inflatable leg splints in prevention of hypotension during spinal anaesthesia was assessed in an open study of 46 patients undergoing elective caesarean section. All patients received 15 ml/kg of Hartmann's solution before spinal anaesthesia and were tilted to the left to minimise aortocaval compression. ⋯ Blood pressure was measured by a cuff method at 1-min intervals until the commencement of surgery. Hypotension was less common (P less than 0.05) and less severe (P less than 0.05) in splint-treated patients, but the incidence was unacceptably high in both treated (48%) and control (83%) groups.
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Acta Anaesthesiol Scand · Oct 1988
Alterations in the pharmacokinetic properties of amide local anaesthetics following local anaesthetic induced convulsions.
The comparative pharmacokinetic properties of lidocaine, bupivacaine, etidocaine and mepivacaine were investigated in convulsing and non-convulsing dogs. The same dose of a given local anaesthetic was administered as either a 30-s intravenous (IV) bolus to produce convulsions or as a 15-min IV infusion producing no convulsions. Derived pharmacokinetic data were found to be different in convulsing and non-convulsing animals. ⋯ Overall, the most profound effects of convulsions on pharmacokinetic data were seen with mepivacaine. Convulsions were associated with increases in heart rate ranging from 117% (lidocaine, P less than 0.05) to 129% (mepivacaine, P less than 0.05), increases in cardiac output ranging from 78% (mepivacaine) to 232% (bupivacaine, P less than 0.05) and increases in mean arterial pressure ranging from 45% (lidocaine, P less than 0.05) to 80% (bupivacaine, P less than 0.05). The results suggest that when local anaesthetic-induced seizures occur in man, it cannot be assumed that these drugs will be distributed and eliminated as predicted by intravenous infusion of non-toxic doses.
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Acta Anaesthesiol Scand · Oct 1988
Pharmacokinetics and protein binding of bupivacaine in postoperative epidural analgesia.
We describe a method, which is both specific and rapid, for the measurement of bupivacaine concentrations in plasma using high-performance liquid chromatography. Bupivacaine plasma concentrations, pharmacokinetics and protein binding in the postoperative period were investigated in seven patients (58-77 years old) following hip surgery. Postoperative analgesia was achieved by epidural bolus injections of 25 mg bupivacaine 0.25% every 6 h. ⋯ The free fraction decreased from 5.4% preoperatively to 2.7% in the postoperative period (P less than 0.05). Changes in plasma protein binding of bupivacaine and changes in plasma levels of the acute phase reactant alpha-1-acid glycoprotein were correlated (r = 0.8, P less than 0.05). Difficulties in interpreting the elimination parameters following epidural administration are discussed, leading to the conclusion that the derivation of dosage regimens from kinetic parameters following epidural administration is not warranted.
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Acta Anaesthesiol Scand · Oct 1988
Vasopressor therapy for hypotension due to epidural anesthesia for cesarean section.
Maternal hemodynamic changes and neonatal acid-base status were assessed in 127 healthy patients undergoing elective cesarean section under epidural anesthesia. An impedance cardiograph was used to measure stroke volume (SV), ejection fraction (EF) and end-diastolic volume (EDV). In addition, neonatal umbilical venous and arterial PO2, PCO2, pH, base excess, lactate, pyruvate, excess lactate, and L/P ratio were measured at birth. ⋯ Both vasopressors restored BP, SV and EDV to near baseline values. Neonatal Apgar scores and acid-base profiles were not significantly different among the three groups of neonates, nor were they different between the two hypotensive groups. It is concluded that: 1) transient maternal hypotension does not affect neonatal acid-base status; 2) both ephedrine and phenylephrine increase cardiac preload; and 3) an alpha agent like phenylephrine does not cause fetal acidosis when used for treating maternal hypotension.
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Acta Anaesthesiol Scand · Oct 1988
Comparative StudyPrimary evaluation of the local anaesthetic properties of the amino amide agent ropivacaine (LEA 103).
The local anaesthestic properties of 1-propyl-2',6'-pipecoloxylidide, a congener of mepivacaine and bupivacaine, and its enantiomers were compared in animals. The (S)-enantiomer (ropivacaine, LEA 103) produced a longer duration of sciatic nerve block and infiltration anaesthesia than the racemate and the (R)-form. Ropivacaine and bupivacaine were equally potent in terms of block of evoked action potential in vitro and minimum effective concentration in vivo. ⋯ Ropivacaine was less toxic (i.v. and s.c. LD50-values) than bupivacaine but more toxic than lidocaine, and produced only weak local irritation. Due to a combination of interesting local anaesthetic properties and relative safety including cardiotoxic potential, we consider ropivacaine a candidate for further studies.