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The effects of biphasic waveform design on post-resuscitation myocardial function

Wanchun Tang, MD^*,*, Max Harry Weil, MD, PhD^*, Shijie Sun, MD^*, Dawn Jorgenson, PhD, Carl Morgan, MSEE, Kada Klouche, MD^* and David Snyder, MSEE

^* Institute of Critical Care Medicine, Palm Springs, California, USA
Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
Philips Medical Systems, Seattle, Washington, USA

View larger version (30K): [in a new window]   Figure 1 Biphasic waveforms used for the present study. Low-energy biphasic truncated exponential (BTEL) uses a 100-µF defibrillation capacitor, whereas high-energy biphasic truncated exponential (BTEH) uses 200-µF.

View larger version (18K): [in a new window]   Figure 2 Energy versus electrical current relationships for the therapies used in the study (circles and error bars indicate median and interquartile range): (A) peak current versus energy; (B) average current versus energy. BTEH = high-energy biphasic truncated exponential; BTEL = low-energy biphasic truncated exponential.

View larger version (30K): [in a new window]   Figure 3 Resuscitation characteristics (median and interquartile range) versus therapy as a percentage of the overall median for each characteristic. Overall median values: shocks = 3.5, total energy = 770 J, cardiopulmonary resuscitation (CPR) = 158 s. *BTEH 200 J data exclude three of five animals that failed resuscitation and are therefore biased low. BTEH = high-energy biphasic truncated exponential; BTEL = low-energy biphasic truncated exponential.

View larger version (61K): [in a new window]   Figure 4 Hemodynamic outcome variables versus therapy at 30 and 240 min post resuscitation shown as median and interquartile range: (A) left ventricular ejection fraction (EF); (B) stroke volume (SV); (C) fractional area change (FAC); (D) mean aortic pressure (MAP); and (E) cardiac output (CO). *BTEH 200 J data exclude three of five animals that failed resuscitation and are therefore biased high. BTEH = high-energy biphasic truncated exponential; BTEL = low-energy biphasic truncated exponential.

View larger version (38K): [in a new window]   Figure 5 Effect of energy, peak current, and average current on outcome variables expressed as the normalized multiple regression coefficients (beta). CO = cardiac output; CPR = duration of cardiopulmonary resuscitation; E = energy; FAC = fractional area change; LVEF = left ventricular ejection fraction; MAP = mean aortic pressure; SV = stroke volume.