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Inspiration Induced by Phrenic Nerve Stimulation Increases Internal Defibrillation Energy Requirements
Author(s) -
EULER DAVID E.,
WHITMAN TERESA A.,
KALLOK MICHAEL J.
Publication year - 1999
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.1999.tb00196.x
Subject(s) - medicine , defibrillation , expiration , phrenic nerve , anesthesia , ventricular fibrillation , stimulation , cardiology , respiratory system
Active Inspiration Affects Defibrillation. Introduction : The purpose of this study was to systematically evaluate the effects of active inspiration induced by phrenic nerve stimulation on the energy required for 50% successful defibrillation (E50). Methods and Results : Shocks (95‐μF biphasic waveform) were delivered after 10 seconds of ventricular fibrillation between a right ventricular coil and left pectoral test can in ten anesthetized pigs (25 to 37 kg). Using a 1‐J step size, the E50 was determined with an up/down, three‐reversal method. Positive‐pressure ventilation was halted just before fibrillation, and shocks were delivered during expiration or at the end of 2 seconds of bilateral phrenic stimulation (50 Hz, 0.3 msec, 5 to 6 V). Phrenic stimulation produced inspiratory volumes that were 15.3 ± 1.7 mL/kg (mean ± SD). The E50 was 9.8 ± 1.9 J during expiration and increased to 13.0 ± 1.7 during inspiration (P = 0.001). The leading‐edge voltage at the K50 was 451 ± 46 V during expiration and 519 ± 33 V during inspiration (P = 0.001). The leading‐edge current at the E50 was 9.7 ± 1.0 A during expiration and increased to 11.3 ± 1.4 A during inspiration (P = 0.002). The average impedance was 47.8 ± 2.7 Ω during expiration and 47.3 ± 3.3 Ω during inspiration (P = 0.12). Conclusion : Inspiration induced by phrenic stimulation results in a 31% increase in the E50 compared with expiration. The decrease in shock efficacy occurs in the absence of a change in impedance. Active inspiration may alter the distribution of the electrical field leading to a decrease in shock efficacy.