Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2005
Enantioselective actions of bupivacaine and ropivacaine on coronary vascular resistance at cardiotoxic concentrations.
The main concern with the use of the long-acting local anesthetics bupivacaine and ropivacaine is inadvertent IV injection, which exposes the heart to toxic drug concentrations. We tested the hypothesis that these chiral anesthetics exert enantioselective actions on coronary vascular tone, the regulation of which does not involve voltage-gated Na(+) channels. Coronary perfusion pressure (CPP) was continuously measured in isolated hearts perfused via the aorta at a constant flow rate. ⋯ We also showed that the putative uncoupler bupivacaine did not depolarize mitochondria in intact ventricular myocytes. In conclusion, the long-acting local anesthetics have enantioselective actions on coronary resistance vessels. Racemic bupivacaine and R(+)-bupivacaine are coronary vasodilators, whereas S(-)-bupivacaine, S(-)-ropivacaine and, to a lesser extent, R(+)-ropivacaine all induce coronary vasoconstriction.
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Anesthesia and analgesia · Mar 2005
Case ReportsThe use of a laryngeal mask airway for emergent airway management in a prone child.
A 5-yr-old girl with Arnold-Chiari Malformation, Type 1, was accidentally tracheally extubated while positioned prone in a Mayfield neurosurgical headrest during a decompressive craniectomy and cervical laminectomy. While preparations were being made to return the patient to the supine position for reintubation, we placed a laryngeal mask airway (LMA) without difficulty. The child was kept in the prone position with the LMA in place using positive-pressure ventilation for the remainder of the operation. This case report emphasizes the practical, emergent use of a LMA to secure the airway of a pediatric patient in the prone position after accidental extubation.
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Anesthesia and analgesia · Mar 2005
Randomized Controlled Trial Clinical TrialAdding clonidine to the induction bolus and postoperative infusion during continuous femoral nerve block delays recovery of motor function after total knee arthroplasty.
We evaluated the effects of adding clonidine for continuous peripheral nerve infusions. Sixty patients undergoing total knee arthroplasty under combined single-injection sciatic block and continuous femoral infusion were randomly allocated to three groups: block induction with 0.75% ropivacaine followed by 0.2% ropivacaine (group control; n = 20); block induction with 0.75% ropivacaine and 1 microg/kg clonidine followed by 0.2% ropivacaine (group cloni-bolus; n = 20), and block induction with 0.75% ropivacaine and 1 microg/kg clonidine followed by 0.2% ropivacaine with 1 microg/mL clonidine (group cloni-infusion; n = 20). After surgery, continuous femoral infusion was provided with a patient-controlled infusion pump (basal infusion rate, 6 mL/h; incremental dose, 2 mL; lockout time, 15 min). ⋯ Hemodynamic profiles and sedation were similar in the three groups. Motor function impairment after 48 h of infusion was observed in 27% of cloni-infusion patients but in only 6% of both the control and cloni-bolus groups (P = 0.05). We conclude that adding clonidine 1 microg/mL to local anesthetic for continuous femoral nerve block does not improve the quality of pain relief but has the potential for delaying recovery of motor function.