Brain Blood Flow and CO2 Articles

Our team sees one problem under most POTS, dysautonomia and ME/CFS symptoms: the brain can't keep its blood flow steady when you stand. Your CO2 level, your posture and your neck all change that flow, and each one can be measured.

How does the brain control its own blood flow?

  1. Your Brain's Secret Blood Flow Control System

    Your brain controls blood flow separately from the rest of your body. Learn why that matters for POTS and why normal BP doesn't mean normal brain perfusion.

  2. Cerebral Hypoperfusion: Why Your Brain Isn't Getting Enough Blood

    Cerebral hypoperfusion means too little blood reaching the brain. What hypoperfusion is, symptoms, causes, why normal blood pressure misses it, and tests.

  3. Proof That the Brain Controls the Autonomic System

    Proof that the brain controls the autonomic system: using eye movements, cerebral blood flow data, and real patient outcomes from targeted brain rehab.

  4. The “Little Brain” That May Be Causing Your Dysautonomia

    Cerebellar dysfunction causes dysautonomia and POTS. Learn how the cerebellum regulates autonomic reflexes and how eye movement testing reveals it.

What happens to brain blood flow when you stand?

  1. Why Does My Heart Race When I Stand Up?

    Why your heart races when you stand up, how much of a rise is typical and when it's POTS. Check your own numbers and see what the faster heart is making up for.

  2. Orthostatic Cerebral Hypoperfusion Syndrome: When Your Brain Loses Blood Flow but Every Test Looks Normal

    Orthostatic cerebral hypoperfusion syndrome (OCHOS) is a measurable drop in brain blood flow on standing. Learn how it differs from standard POTS.

  3. POTS vs OCHOS: Why the 30 BPM Line Doesn't Mean What You Think

    POTS and OCHOS share one core problem: reduced cerebral blood flow. The 30 BPM threshold dividing them is a 40-year-old artifact, not a biological boundary.

  4. Blood Pooling in Your Legs, Hands and Feet: What Causes It

    Blood pooling is blood collecting in your legs, feet or hands when you're upright. What it looks like, when it's normal, and what causes it in POTS.

  5. POTS: When Your Brain Loses Its Balance

    POTS isn't just about heart rate. Learn why it's really a brain coordination problem, and why treating it as a heart condition misses the mechanism.

What does CO2 have to do with it?

  1. Carbon Dioxide: One of the Most Important Metrics for Brain Blood Flow

    CO2 isn't a waste product. It's a key signal your brain uses to regulate blood flow. Why we measure ETCO2 on the tilt table, and what low CO2 feels like.

  2. Hypocapnic Cerebral Hypoperfusion (HYCH): How Low CO2 Cuts Blood Flow to the Brain

    Hypocapnic cerebral hypoperfusion (HYCH) is low brain blood flow on standing from low CO2, without the POTS heart rate. Symptoms, POTS link, tests, treatment.

Can your neck restrict blood flow to the brain?

  1. Can Your Neck Actually Restrict Blood Flow to Your Brain?

    Tight neck muscles, forward head posture, and cervical misalignment can reduce cerebral blood flow. How your neck affects your brain, and what to do.

  2. Neck Problems and the Brain: 7 Ways Your Neck Drives Brain Fog, Dizziness and POTS

    Neck problems can cause brain fog, memory trouble, dizziness and POTS symptoms. See the 7 ways cervical joint errors reach the brain and how they're tested.

  3. Your Neck Might Be Part of the Problem

    Neck stiffness with dysautonomia isn't random. Learn the neurological connection between your neck, vestibular system, and autonomic symptoms.

  4. Ear Fullness and Popping in POTS: The Drainage Problem Behind It

    Ear fullness, popping, pressure or ringing with POTS? It often traces to how blood drains from your head. See the mechanism, the evidence and what helps.

What does low brain blood flow feel like?

  1. Brain Fog Isn't a Diagnosis: What's Actually Happening in Your Brain

    Brain fog isn't a diagnosis: it's a symptom of processing inefficiency. Learn the neurological causes and why treating the symptom doesn't work.

  2. You're Not Lazy: Your Brain Is Running on Empty

    POTS fatigue and brain fog aren't laziness. Dr. Keiser explains why reduced cerebral blood flow starves your brain of fuel and what testing can reveal.

  3. Derealization and POTS: Why You Feel Detached From Reality

    Feeling detached from reality with POTS? Derealization often follows blood flow to the brain and the balance system. How to tell which, and what to test.

  4. Exercise Intolerance in POTS: It's Not Just Deconditioning

    Exercise intolerance in POTS isn't just deconditioning. Learn why 'just exercise more' fails and what's really happening in the brain when you push through.

How is brain blood flow measured?

  1. Why We Use Transcranial Doppler for POTS

    Heart rate is only part of the POTS story. Transcranial Doppler ultrasound reveals what's really happening to blood flow in your brain when you stand.

For how this plays out in each condition, see the POTS, ME/CFS and long COVID pages.

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