| The Isolated Arm Test for the Assessment of Neuromuscular Blockade. |
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Sung Yell Kim, Soon Im Kim, Kyung Ho Hwang, Sun Chong Kim, Wook Park |
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Department of Anesthesiology, College of Medicine, Soon Chun Hyang University, Seoul, Korea. |
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| Abstract |
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Subjects should not have any factors affecting neuromuscular transmission. Anestheisa was induced by a sleep dose of 2.5% thiopental sodium, and oxygen, nitrous oxide and lower concentration of enflurane were used for maintenance. When the patients were stabilized, the arm with electrode attached and an indwelling needle inserted into a vein on the back of the wrist, was elevated for 30 seconds to partially drain the blood from it and then pneumatic tourniquet inflated 30 to 40 mmHg above the systolic blood pressure around the upper arm, so that a small dose of relaxants (1/60 or 1/30 of the clinical dose; succinylcholine 1mg/kg, vecuronium 0.08 mg/kg, atracurium 0.2 mg/kg, pancuronium 0.08 mg/kg and alpha-tubocurarine 0.2 mg/kg) could be injected into the arm isolated from the systemic circulation. Thereafter, ischemia was maintained for 4 minutes to allow retrograde spread of some of the drugs into the capillary bed where neuromuscular block was established. At the end of 4 minutes after tourniquet applied, the tourniquet was released. Neuromuscular conduction was recorded using ABM monitor of the Datex Co.
for neuromuscular transmssion by 40 mA 2Hz stimulaton to ulnar nerve 20 seconds interval. We confirmed the marked rundown of amplitude of muscle action potensial (MAP) in group injected very small doses throughout the isolated limb but no affect the evoked MAP in group injected into systemic circulation. Conclusively, even there are various factors affecting extent of block by the tournique; ischemic acidosis, concentration volume of drugs, amovnt of exsanguination and the state of vasculare bed, these were not thought to be a source of error for study. Therefore small doses of relaxants required wih this technique exclude the possibility of unwanted systemic side effects and can be reliable and effective for clinical study for neuromuscular transmission. |
| Key Words:
Neuromuscular relaxants; Measurement techniques |
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