Anesthesia and analgesia
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Anesthesia and analgesia · May 2008
Comparative StudyDo new anesthesia ventilators deliver small tidal volumes accurately during volume-controlled ventilation?
During mechanical ventilation of infants and neonates, small changes in tidal volume may lead to hypo- or hyperventilation, barotrauma, or volutrauma. Partly because breathing circuit compliance and fresh gas flow affect tidal volume delivery by traditional anesthesia ventilators in volume-controlled ventilation (VCV) mode, pressure-controlled ventilation (PCV) using a circle breathing system has become a common approach to minimizing the risk of mechanical ventilation for small patients, although delivered tidal volume is not assured during PCV. A new generation of anesthesia machine ventilators addresses the problems of VCV by adjusting for fresh gas flow and for the compliance of the breathing circuit. In this study, we evaluated the accuracy of new anesthesia ventilators to deliver small tidal volumes. ⋯ Newer generation anesthesia machine ventilators that compensate for breathing circuit compliance and for fresh gas flow are able to deliver small tidal volumes accurately to the airway under conditions of normal and low lung compliance during volume-controlled ventilation. Accurate VCV may be a useful alternative to PCV, as volume is guaranteed when lung compliance changes, and new strategies such as small volume/lung protective ventilation become possible in the operating room.
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Anesthesia and analgesia · May 2008
Case ReportsIntravenous lipid infusion in the successful resuscitation of local anesthetic-induced cardiovascular collapse after supraclavicular brachial plexus block.
We describe a case of successful resuscitation with an i.v. lipid infusion of local anesthetic-induced cardiovascular toxicity after supraclavicular brachial plexus block with mepivacaine and bupivacaine. Lipid therapy was initiated after 10 min of unsuccessful resuscitation and resulted in restoration of cardiovascular activity and hemodynamic stability. This case illustrates the utility of i.v. lipid therapy in the treatment of local anesthetic toxicity.
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Anesthesia and analgesia · May 2008
Case ReportsSuccessful resuscitation after ropivacaine and lidocaine-induced ventricular arrhythmia following posterior lumbar plexus block in a child.
We report the case of a 13-yr-old girl scheduled for knee surgery under general anesthesia and posterior lumbar plexus block. A ventricular arrhythmia developed 15 min after local anesthetic injection. ⋯ This is consistent with previous reports suggesting that lipid emulsion is an effective emergency treatment of local anesthetic toxicity. We recommend the immediate availability of lipid emulsion along with other emergency therapeutics in operating rooms where local anesthetics are used.
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Anesthesia and analgesia · May 2008
Case ReportsReversal of central nervous system and cardiac toxicity after local anesthetic intoxication by lipid emulsion injection.
A 91-yr-old man (57 kg, 156 cm, ASA III) received an infraclavicular brachial plexus block for surgery of bursitis of the olecranon. Twenty minutes after infraclavicular injection of 30 mL of mepivacaine 1% (Scandicain) and 5 min after supplementation of 10 mL of prilocaine 1% (Xylonest) using an axillary approach, the patient complained of agitation and dizziness and became unresponsive to verbal commands. In addition, supraventricular extrasystole with bigeminy occurred. ⋯ Plasma concentrations of local anesthetics were determined before, 20, and 40 min after lipid infusion and were 4.08, 2.30, and 1.73 microg/mL for mepivacaine and 0.92, 0.35, and 0.24 microg/mL for prilocaine. These concentrations are below previously reported thresholds of toxicity above 5 microg/mL for both local anesthetics. Signs of toxicity resolved and the patient underwent the scheduled surgical procedure uneventfully under brachial plexus blockade.
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Anesthesia and analgesia · May 2008
Lidocaine increases intracellular sodium concentration through a Na+-H+ exchanger in an identified Lymnaea neuron.
The intracellular sodium concentration ([Na(+)]in) is related to neuron excitability. For [Na(+)]in, a Na(+)-H(+) exchanger plays an important role, which is affected by intracellular pH ([pH]in). However, the effect of lidocaine on [pH]in and a Na(+)-H(+) exchanger is unclear. We used neuron from Lymnaea stagnalis to determine how lidocaine affects [pH]in, Na(+)-H(+) exchanger, and [Na(+)]in. ⋯ Lidocaine increases the [Na(+)] through a Na(+)-H(+) exchanger by proton trapping.