Purpose or Case Report: The purpose of this experiment was to evaluate the correlation between the doppler and intracranial pressure (ICP) and mean arterial pressure (MAP) in a pediatric porcine model of asphyxia-associated cardiac arrest.
Methods & Materials: In 6 infant piglets, a bolus of 0.1 dose mL of ultrasound contrast (Lumason, Bracco Diagnostics Inc) was injected into swine during 10 minutes pre-asphyxia (baseline) and 3 hours post-return of spontaneous circulation (ROSC). During each period, 2-3 boluses were performed. Early washout rates were acquired when CEUS intensities of the bolus was 30% of the maximum intensity. In addition, Time to peak (TTP) and peak enhancement were measured. ICP was collected continuously and later normalized to the baseline. Average relative changes of ICP, TTP, early washout rate, and peak enhancement from baseline to 3 hours post-ROSC were compared.
Results: The average of peak systolic velocity at baseline was 14.01 cm/s and at 3 hours post-ROSC was 15.03 cm/s. The average of end diastolic velocity at baseline was 7.11 cm/s and at 3 hours post-ROSC was 3.73 cm/s. The average of normalized ICP at baseline was 0.97 a.u. and at 3 hours post-ROSC was 1.26 a.u.. The average of the normalized MAP at baseline was 1.01 a.u. and at 3 hours post-ROSC was 1.12 a.u.. The difference between values at baseline and 3 hours post-ROSC for all parameters are statistically insignificant (p=0.60, p=0.75, p=0.47, and p = 0.11 for peak systolic velocity, end diastolic velocity, MAP, and ICP respectively). Both peak systolic velocity and end diastolic velocity had a negative linear correlation with MAP, both with Pearson coefficients of -0.86. The variation in peak systolic velocity and end diastolic velocity that is relative to the variation in MAP is 74.0%. There was no significant linear correlation between peak systolic velocity or end diastolic velocity with ICP, with a Pearson coefficient of -0.01 for peak systolic velocity and a coefficient of -0.13 for end diastolic velocity. The variation in peak systolic velocity and end diastolic velocity that is relative to the variation in ICP is 1.7%.
Conclusions: This preliminary investigation reveals that the early washout rate, but not TTP or peak enhancement, is strongly correlated with ICP, indicating that the bolus-based early washout rate change can be used to predict ICP changes. CEUS intensity has less risk associated with it than invasive hemodynamic measurements such as ICP, offering a safer alternative method.