Targeted Delivery of Electrical Shocks and Epinephrine, Guided by Ventricular Fibrillation Amplitude Spectral Area, Reduces Electrical and Adrenergic Myocardial Burden, Improving Survival in Swine

Figures

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  Figure 1. Shown are examples of the algorithm used to advise epinephrine (Epi) delivery based on the projected amplitude spectral area (AMSA) value 120 seconds ahead. The current and the 4 trailing AMSA values were entered in the regression equation used for the projection. Black circles represent actual AMSA values, and white circles represent the projected AMSA value 120 seconds ahead of the current AMSA value. If the projected AMSA was ≥11.4 mV‐Hz, Epi was not advised (red lines). If the projected AMSA was <11.4 mV‐Hz, Epi was advised (green lines). A, AMSA projected to be <11.4 mV‐Hz after the first “Epi Check” at 240 seconds, prompting Epi delivery immediately on resumption of chest compressions. B, AMSA projected to be ≥11.4 mV‐Hz, advising against Epi delivery after the first “Epi‐Check”. C, AMSA projected to be ≥11.4 mV‐Hz in 4 consecutive “Epi Checks,” advising against Epi, as shown by red discontinued lines, until the projection drops below the 11.4 mV‐Hz, advising Epi delivery. D, Despite repeated advisories against Epi, Epi was delivered after meeting the time threshold at 360 seconds.

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  Figure 2. Swine model of electrically induced ventricular fibrillation (VF) with resuscitation attempted by conventional cardiopulmonary resuscitation using a mechanical piston device and bag‐valve ventilation through an endotracheal tube with delivery of 100% oxygen. DEFIB indicates defibrillator; and PETCO2, end‐tidal Pco 2.

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  Figure 3. Kaplan‐Meier survival curves analyzed from the time ventricular fibrillation (VF) was induced in all 24 animals (A) and from the time return of spontaneous circulation (ROSC) was achieved in 19 animals (B), comparing the 3 resuscitation protocols: guidelines‐driven (GD), amplitude spectral area (AMSA)–driven shocks (ADS), and AMSA‐driven shocks and epinephrine (ADSE). Failure to achieve ROSC resulted in every instance from persistent VF. The overall P value, calculated using the log‐rank test, is shown in the graph.

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  Figure 4. Graphs depicting the 3 resuscitation protocols: guidelines‐driven (GD), amplitude spectral area (AMSA)–driven shocks (ADS), and AMSA‐driven shocks and epinephrine (ADSE), showing: the time to deliver the first shock (A); number of electrical shocks delivered during cardiopulmonary resuscitation (CPR) (*P=0.030 vs GD) (B); number of epinephrine doses (C); and duration of CPR in animals that achieved return of spontaneous circulation (ROSC) (D). Differences among groups were analyzed by 1‐way ANOVA using the Holm‐Sidak test for pairwise comparisons if the data were normally distributed; otherwise, the Kruskal‐Wallis test on ranks with Tukey test for pairwise comparisons was used, correspondingly showing means±SD with data shown in bar graphs or median (quartile1–quartile 3) with data shown in box plots. The P value for the overall test is shown in the graph.

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  Figure 5. Graphs arranged according to the resuscitation protocol, guidelines‐driven (GD), amplitude spectral area (AMSA)–driven shocks (ADS), and AMSA‐driven shocks and epinephrine (ADSE), showing electrical burden calculated as described in the text (A) and adrenergic burden calculated as described in the text (B). Differences among groups were analyzed by 1‐way ANOVA using the Holm‐Sidak test for pairwise comparisons if the data were normally distributed; otherwise, the Kruskal‐Wallis test on ranks with Tukey test for pairwise comparisons was used, correspondingly showing means±SD with data shown in bar graphs or median (quartile 1–quartile 3) with data shown in box plots. The P value for the overall test is shown in the graph.

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  Figure 6. Graphs showing the relationship between electrical burden and adrenergic burden with 240‐minute survival and postresuscitation left ventricular stroke work index (LVSWI) identifying the resuscitation protocol that each animal received: guidelines‐driven (white symbols), amplitude spectral area (AMSA)–driven shocks (gray symbols), and AMSA‐driven shocks and epinephrine (black symbols). A, Linear regression between electrical burden and survival time after return of spontaneous circulation (ROSC). B, Linear regression between adrenergic burden and survival time after ROSC. C, Linear regression between electrical burden and LVSWI averaged across the entire postresuscitation interval. D, Linear regression between adrenergic burden and LVSWI averaged across the entire postresuscitation interval. All graphs show the corresponding 95% CI for the regression analysis.