Cerebral blood flow velocity during simultaneous changes in mean arterial pressure and cardiac output in healthy volunteers

Abstract

Purpose Cerebral blood flow (CBF) needs to be precisely controlled to maintain brain functions. While previously believed to be autoregulated and near constant over a wide blood pressure range, CBF is now understood as more pressure passive. However, there are still questions regarding the integrated nature of CBF regulation and more specifically the role of cardiac output. Our aim was, therefore, to explore the effects of MAP and cardiac output on CBF in a combined model of reduced preload and increased afterload. Method 16 healthy volunteers were exposed to combinations of different levels of simultaneous lower body negative pressure and isometric hand grip. We measured blood velocity in the middle cerebral artery (MCAV) and internal carotid artery (ICAV) by Doppler ultrasound, and cerebral oxygen saturation (ScO2) by near-infrared spectroscopy, as surrogates for CBF. The effect of changes in MAP and cardiac output on CBF was estimated with mixed multiple regression. Result Both MAP and cardiac output had independent effects on MCAV, ICAV and ScO2. For ICAV and ScO2 there was also a statistically significant interaction effect between MAP and cardiac output. The estimated effect of a change of 10 mmHg in MAP on MCAV was 3.11 cm/s (95% CI 2.51–3.71, P < 0.001), and the effect of a change of 1 L/min in cardiac output was 3.41 cm/s (95% CI 2.82–4.00, P < 0.001). Conclusion The present study indicates that during reductions in cardiac output, both MAP and cardiac output have independent effects on CBF.

Effects of Auricular Point Acupressure with Lifestyle Interventions on Cerebrovascular Function among Adults with High Stroke Risk: A Randomized Controlled Study

“…It was well known that the APA therapy can lower the blood pressure [15,21,22], while the cerebral blood fow was believed to be autoregulated and near constant over a wide blood pressure range and therefore was not largely afected by the change of the blood pressure. However, a very recent study has proved that mean arterial pressure has independent efects on the blood velocity in middle cerebral artery and internal carotid artery [31]. Terefore, the blood pressure may play an intermediary role in the relevance between the APA therapy and CVHP.…”

Cerebral oxygenation and cardiac output responses during short repeated-sprints exercise and modulatory effect of glucose ingestion

“…Cardiac output directly influences CBF and cerebral oxygenation independently from changes in arterial blood pressure (Castle-Kirszbaum et al, 2022; Lie et al, 2021; Ogoh, Brothers, et al, 2005). In our study, cardiac output values during the sprints were moderately and positively correlated with ΔO 2 Hb and ΔtHb, which suggests that cardiac output might contribute to changes in CBF and cerebral oxygenation during the repeated sprints.…”

Effects of supplemental oxygen on systemic and cerebral hemodynamics in experimental hypovolemia: Protocol for a randomized, double blinded crossover study

“…By increasing the duration of each LBNP-level, we could potentially increase the number of decompensations at the cost of fewer observations at high LBNP-levels. Based on the decompensation rate in prior work [15,18], we believe that the present LBNP protocol will be able to reveal an effect of oxygen on time to decompensation, i.e. LBNP tolerance.…”