P7.8 THE RELATIONSHIP BETWEEN RENAL AND CEREBRAL BLOOD FLOW PULSATILITY

Abstract

Introduction: Increased pulsatile flow has been implicated in the progression of microvascular damage. The pulsatile blood flow transmitted into both the brain and kidney are often assumed to be similar, however specific studies confirming these associations are lacking. Therefore, the aim of this study was to investigate the relationship of pulsatility index (PI) and resistive index (RI) [both measures of pulsatile flow] between the renal artery (RA) and middle cerebral artery (MCA). Methods: Thirty-one participants (aged 36±11 years) were recruited from Cardiff Metropolitan University’s Staff Health and Wellbeing study. Peak systolic velocity, end diastolic velocity and mean velocity were all measured and used to calculate PI (Gosling’s) and RI (Pourcelot’s) of the RA (renal ultrasound, Vivid Q, GE) and MCA (Transcranial Doppler, DWL). Correlation and level of agreement (LOA) between RA PI and MCA PI were analysed using Pearson correlation coefficient and Bland-Altman plots. Results: Although, a linear relationship was observed between RA PI and MCA PI (r=0.477, adjusted R2=0.201, P=0.007) and between RA RI and MCA RI (r=0.513, adjusted R2=0.238, P=0.003), further Bland-Altman analysis demonstrated a PI bias of 0.37±0.26 and LOA of −0.15 to 0.89. Conclusion: These data suggest that the agreement between flow pulsatility within the renal and middle cerebral arteries are not similar. Our data indicate that the measurement of PI in the renal artery only explains 20% of the variance in PI observed in the MCA. Therefore, caution should be taken when assuming similarity in PI and RI between different organs.