1/7 Great to see the enthusiastic responses to my #autoregulation tweets. This is what keeps Twitter great and now I know I'm not the only #autoregulation #nerd. A few more tweets about autoregulation and CBF as a follow-up:
2/7 When you think about autoregulation and cerebral blood flow (CBF), keep in mind that, even if autoregulation works normally, or blood pressure (BP) is stable, there are other things that can and will affect CBF:
3/7
1. For example, when you hyperventilate, CBF can be reduced by 30%, even if BP does not change.If you hold your breath (without doing a Valsalva) CBF can increase by 50 % (or even more).
1. For example, when you hyperventilate, CBF can be reduced by 30%, even if BP does not change.If you hold your breath (without doing a Valsalva) CBF can increase by 50 % (or even more).
4/7
2. With longstanding hypertension, even if #autoregulation is normal (which it usually is in patients with hypertension), there is a gradual decline in CBF. We think around 10%. Good news: this is reversible with BP lowering treatment.
2. With longstanding hypertension, even if #autoregulation is normal (which it usually is in patients with hypertension), there is a gradual decline in CBF. We think around 10%. Good news: this is reversible with BP lowering treatment.
5/7
3. An important function of CBF is delivery of oxygen to brain tissue. But even if CBF is maintained, oxygen delivery can be impaired when oxygen diffusion across capillaries is limited (e.g. inflammation).
3. An important function of CBF is delivery of oxygen to brain tissue. But even if CBF is maintained, oxygen delivery can be impaired when oxygen diffusion across capillaries is limited (e.g. inflammation).
6/7
4. When neurovascular coupling is impaired, despite intact global CBF and stable BP, local blood supply to activated brain regions may fall short.
4. When neurovascular coupling is impaired, despite intact global CBF and stable BP, local blood supply to activated brain regions may fall short.
7/7
Brain blood vessels are not just tubes that deliver blood. They also have other functions that are now being discovered. For example, their arterial pulsations may be a driving force of a pump system that regulates interstitial fluid flow.
Brain blood vessels are not just tubes that deliver blood. They also have other functions that are now being discovered. For example, their arterial pulsations may be a driving force of a pump system that regulates interstitial fluid flow.
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