During hemorrhagic shock and after resuscitation, the left ventricular pressure (LVP) and volume (LVV) vary over time. This study investigates and characterizes the LVP and LVV signals in the frequency and time domains in a hemorrhagic shock-resuscitation model. 40% of blood volume was withdrawn from anesthetized hamsters to induce moderate hemorrhagic shock conditions. A single volume infusion of the plasma expander (Hextend: hydroxyethyl starch) was administered after 30 min of the beginning of hemorrhagic shock. LVP and LVV were measured using a miniaturized pressure-volume conductance catheter. The fast Fourier transform and trajectory plot of both signals were performed for frequency and time domains analysis, respectively. Preliminary results show that, during shock stage, the amplitudes of the LVP spectrum at the 2nd and 4th harmonics were significantly higher compared with baseline and 30 min after resuscitation (p<0.01). We also found that the trajectory plot of LVP showed a markedly difference between normal conditions at baseline and the shock condition. However, there was no significant information in the LVV signal either in frequency or time domain during hemorrhagic shock-resuscitation. These findings demonstrated the applicability of frequency and time domains analysis of LVP signal for use as an alternative diagnostic tool.
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