Efecto de la viscosidad sanguínea sobre el flujo sanguíneo cerebral en una población residente a gran altitud

Objective: We aimed to determine the correlation between blood viscosity and cerebral blood flow in people acclimated to chronic hypoxia who have high blood viscosity levels. Materials and methods: A Prospective observational study was conducted in asymptomatic young adults living in Cusco (3399 m altitude). All participants were examined at low and high shear rates (75 and 300 s−1) for simulating the dynamic component of blood viscosity. A transcranial Doppler study of the middle cerebral artery was performed to measure systolic, diastolic, and mean flow velocities (FVs), as well as resistance and pulsatility indexes (PIs). Results: One hundred and thirty-one participants were included. Median viscosity levels were 5.01cP (interquartile range [IQR]: 4.45–5.73cP) at 300 s−1 and 6.16 cP (IQR: 5.58-7.20 cP) at 75 s−1, mean FV was 57 cm/s (IQR: 50–65 cm/s), and the PI was 0.91 (0.86–1.02). Blood viscosity was negatively correlated with mean FV (r: −0.17; p=0.007), while it showed no correlation with other values of blood flow, resistance, or PI. R2 determination quotient values were less than 0.1 in all cases. Conclusions: A weak correlation was observed between blood viscosity levels and mean cerebral blood flow velocity, and there was no correlation of other parameters between these two variables. This finding suggests that in young and clinically healthy individuals, there are autoregulation mechanisms that compensate for blood viscosity variations.