Abstract 131: Augmenting Cerebral Blood Flow using Military Anti-Shock Trousers: A Transcranial Doppler Study
Background: Augmenting blood flow through iatrogenically raising blood pressure is one mechanism to augment cerebral blood flow (CBF) which confers benefits to ischemic brain tissue. CBF augmentation has potential applications in acute ischemic stroke to increase collateral flow. The MAST device has previosuly been used to in a cardiac setting to increase cardiac output and raise blood pressure which can increase systemic flow velocities. The aim of this study was to use the MAST device to augment CBF in healthy subjects.
METHODS: In this study 11 healthy volunteers (22 vessels) were given MAST which was inflated while simultaneously measuring heart rate, systolic and diastolic blood pressure. Transcranial Doppler (TCD) was used to measure the flow velocities in the middle cerebral artery (MCA) including peak systolic velocity (PSV), end diastolic velocity (EDV), mean flow velocity (MSV) and to calculate pulsility index (PI) over a 4 minute inflation and 2 minute deflation protocol in the supine position.
Results: After inflation of MAST there was an increase in both systolic and diastolic blood pressure and a slight decrease in PSV (74 vs. 72 cm/s), EDV (33 vs. 32 cm/s) and MFV (50 vs. 49 cm/s) and an increase in PI (0.83 vs. 0.85). After deflation of the MAST device, blood pressure decreased and there was a slight decrease in MFV (49 vs. 48 cm/s) and EDV (32 vs 31 cm/s). PSV was slightly increased (72 vs. 74 cm/s) while PI was greatly increased (0.82 vs. 0.86). Interestingly, two groups were identified based on early and late changes in PI after MAST inflation.
Conclusion: This data suggests that an artificial increase in blood pressure can augment CBF parameters (PSV, EDV, and MFV) and this change is short lived after an increase in blood pressure. A drop in blood pressure will also change CBF parameters, and importantly increase PI as suggested by Doppler waveforms. Cerebrovascular motor reactivity occurs quickly after changes to blood pressure and works to maintain a constant CBF through the MCA.
- © 2012 by American Heart Association, Inc.