Articles: nerve-block.
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We have examined the in vitro sensitivities of A, B and C fibres in rabbit vagus nerves to local anaesthetic block with a range of local anaesthetic drugs. The nerves were maintained at 37 degrees C and pH 7.4 using an electrolyte solution equilibrated with 5% carbon dioxide. A fibres were the most, and C fibres the least, sensitive to block at low frequency stimulation (0.0167 Hz). ⋯ With stimulation at high frequencies (20 and 40 Hz), C fibres were more sensitive to use-dependent block than A fibres; this effect was more marked with drugs containing an amide than an ester linkage. Molecular size and lipid solubility may inter-react to govern the ability to produce use dependent block. Agents which contain an amide linking group, have a high pKa and are of low lipid solubility, may be used to produce differential C fibre block.
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Thorac Cardiovasc Surg · Oct 1989
Repetitive intercostal nerve block via catheter for postoperative pain relief after thoracotomy.
After anterolateral thoracotomy, before incision closure, indwelling plastic catheters were inserted percutaneously under digital and/or visual control into the intercostal space of access and the two neighbouring ones. Initially, we injected 25 mg of bupivacaine through each catheter (to a total of 75 mg), and subsequently - on the patients demand - another 15 to 25 mg per catheter. To date, 25 patients received repetitive intercostal nerve blocks by this method (ICB-group). ⋯ SA: 13%) were observed less frequently than in the control group, whereas tachyarrhythmia occurred in 6 of 25 ICB-patients compared to 4 of 30 SA-patients. Nevertheless, none of these parameters reached statistical significance (p less than 0.05). Maximum bupivacaine levels of 0.65 +/- 0.21 micrograms/ml were found after 29 +/- 12 min of intercostal application.(ABSTRACT TRUNCATED AT 250 WORDS)