Predictions from misleading pig model are potentially harmful to humans

Jones, Janice L.; Snyder, David; Morgan, Carl

doi:10.1016/j.resuscitation.2003.07.003

Cited by 7 publications

(4 citation statements)

References 9 publications

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“…These conclusions were heavily criticised. 10 It was noted that the results were out of context with previously published clinical data. It was suggested that the animal ¡ electronic surrogate model of high impedance defibrillation was inappropriate and the correspondents questioned whether the application of these results to the clinical setting would in fact be harmful.…”

Section: Energy Selection For Biphasic Defibrillatorssupporting

confidence: 62%

“…The main rationale for this argument was that only a limited fraction of the shock dose was delivered to the animals in contrast to the clinical setting where patients with higher TTI receive the full dose. 10 In reply, Walker and colleagues 11 stated that their animal model was appropriate for comparison of relative efficacy between devices and the method of simulating high impedance served this purpose well. However, recent animal data have suggested that higher energy biphasic shocks impact negatively on haemodynamic function after defibrillation.…”

Section: Energy Selection For Biphasic Defibrillatorsmentioning

confidence: 99%

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Theory and practice of defibrillation: (2) defibrillation for ventricular fibrillation

Adgey

Spence²,

Walsh³

2005

Heart

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Section: Energy Selection For Biphasic Defibrillatorssupporting

confidence: 62%

Section: Energy Selection For Biphasic Defibrillatorsmentioning

confidence: 99%

Theory and practice of defibrillation: (2) defibrillation for ventricular fibrillation

Adgey

Spence²,

Walsh³

2005

Heart

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“…1 The addition of series resistance to approximate a more clinically relevant transthoracic impedance effectively models physiologic transthoracic impedance variability as a purely series resistance phenomenon. The supposition that impedance variability is dominated by series effects is consistent with prior clinical data 26,27 and computer modeling findings. 24,25 The potential problems and the merits of this approach have been acknowledged.…”

Section: Limitationssupporting

confidence: 84%

Intracardiac Voltage Gradients during Transthoracic Defibrillation: Implications for Postshock Myocardial Injury

Niemann

Walker

Rosborough

2005

Academic Emergency Medicine

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In-vitro studies indicate that the electric-field intensity, or voltage gradient (VG), generated by a defibrillation shock is a determinant of defibrillation success as well as potential shock-induced cardiac injury. It is not clear how common descriptors of shock dose, e.g., joules (J), relate to VGs. Objectives: To assess the relationships between shock energy descriptors and VG. Methods: One monophasic and three biphasic waveforms were compared using transthoracic shocks and standard electrodes in five swine. VG measurements via intracavitary multielectrode-tipped catheters were compared with delivered energy and peak current. Shock variables were recorded at native transthoracic impedance and an adjusted impedance approximating that of typical humans. Results: For shocks at the same energy setting, peak current and VGs varied widely among the four defibrillators. At simulated human impedance (75 V), shocks at each device's maximum energy setting produced similar VGs among the three biphasic defibrillators, despite different delivered energies. For both native impedance (35 V) and at 75 V, VG correlated with peak current (r = 0.81 and 0.77, respectively) but not energy setting (r = 0.61, 0.52) or delivered energy (r = 0.58, 0.56). At the maximum energy setting of each device, maximum recorded VGs for both monophasic (33 V/cm) and biphasic (24 V/cm) defibrillators were less than those reported to cause myocardial injury (>60 to 80 V/cm). Conclusions: Energy descriptors correlate poorly to actual shock intensities. When compared with reported VG thresholds of myocardial injury, this study suggests that risk of injury from critically strong VGs is low for all of these defibrillators and equivalent among tested biphasic waveforms.

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“…(15,16) However, controversy surrounds the effectiveness of these impedance-compensating processes, and there continues to be a strong belief that TTI signifi cantly affects the ability of modern-day defi brillators to deliver the appropriate level of current to the fi brillating myocardium. (17)(18)(19) The level of peak current required to convert VF in humans needs to be defi ned. Current levels of peak current used are not related in any linear manner to energy delivered.…”

Section: Introductionmentioning

confidence: 99%