Fig. 4. Dynamics of metabolic and hemodynamic correlations. ( A ) The change in rate-pressure product (Δ-RPP) between 7.5 and 15 min over a range of epinephrine doses; curve fit by a two-phase exponential. ( B ) The change in blood lactate levels (Δ-lactate) between 7.5 and 15 min over a range of epinephrine doses; line fit to a Boltzmann sigmoidal curve. ( C ) Δ-RPP versus Δ-lactate; linear regression; r = 0.72. Error bars represent SEM.