Linearity of transthoracic conductance with respect to electrode force and area during high-voltage defibrillation shocks

Canine transthoracic conductance (G/sub T/) was measured during high-voltage defibrillation shocks to test the hypothesis that (G/sub T/) is a linear function of electrode force (F) and electrode area (A). Symmetric protocols were used to compensate for changes in (G/sub T/) with respect to shock number (n). Stainless steel electrodes were employed with a force-control system for precise selection and control of both F and A at each shock. For a constant A=60 cm/sup 2/, G/sub T/ was linear (r=0.996, 0.995, 0.971, 0.992, 0.995) over five dogs for 30 N/spl les/F/spl les/70 N. For a constant F=50 N, G/sub T/ was linear (r=0.992, 0.998, 0.994, 0.992) over four dogs for 20 cm/sup 2//spl les/A/spl les/60 cm/sup 2/, and in one dog (r=0.996) for 40 cm/sup 2//spl les/A/spl les/90 cm/sup 2/. The quantitative relationship demonstrated for G/sub T/ and F and A can be used in the design of experiments and interpretation of results used for validation of numerical defibrillation models.<
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