Articles: anesthetics.
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In summary, the clinical goal in regional anesthesia for hand surgery is to constantly approach the ideal of a well-conducted, smooth, "balanced regional technique." This begins with the preoperative interview, assurance, and preoperative sedation (po). In the operating room, monitoring (EKG, BP) and safety measures (IV port, nasal oxygen) precede the regional technique. The block is performed with asepsis, minimal "needling," and correct dosages. ⋯ Monitoring is continued in the recovery room, where special attention is given to positioning, cushioning of pressure areas, dressing, analgesia, and specific physical rehabilitation exercises. With a "balanced regional technique," the patient becomes an early participant in his or her own postoperative care and result. This balanced technique reduces the patient's overall operative risk and maximizes the surgical result.
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The most important clinical properties of local anaesthetic agents are potency, onset, duration of action and relative blockade of sensory and motor fibres. These qualities are related primarily to the physicochemical properties of the various compounds. ⋯ In general, the local anaesthetics for infiltration, peripheral nerve blockade, and extradural anaesthesia can be classified into three groups: agents of low potency and short duration, for example procaine and chloroprocaine; agents of moderate potency and duration, for example lignocaine, mepivacaine and prilocaine; and agents of high potency and long duration, for example amethocaine, bupivacaine and etidocaine. These local anaesthetics also vary in terms of onset: chloroprocaine, lignocaine, mepivacaine, prilocaine and etidocaine have a rapid onset, while procaine, amethocaine and bupivacaine are characterized by a longer latency period.
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Comparative Study
Amide local anesthetic alterations of effective refractory period temporal dispersion: relationship to ventricular arrhythmias.
The hemodynamic and electrophysiologic effects of bupivacaine, etidocaine, mepivacaine, and lidocaine were investigated in 32 pentobarbital-anesthetized adult mongrel dogs. Following equipotent dosing, all four agents produced similar hemodynamic effects: decrease in stroke volume and cardiac output, heart rate slowing, increase in systemic vascular resistance, and increases in pulmonary arterial pressure (PAP) and pulmonary capillary wedge pressure (PCWP). The effects of the various agents on the ECG were different. ⋯ Six of seven bupivacaine, six of seven etidocaine, two of eight mepivacaine, and none of eight lidocaine animals sustained a polymorphic, undulating ventricular tachycardia similar to Torsades de Pointes following burst ventricular pacing. The results of this study suggest that bupivacaine, etidocaine, and occasionally mepivacaine can result in a Torsades de Pointes-like syndrome following intravenous administration. The magnitude of ERP temporal dispersion differences between the various agents appears to explain their differential arrhythmogenicity.