Carbon dioxide partial pressure

A measure of the pressure contributed by dissolved carbon dioxide in blood. When ventilation exceeds the body’s CO₂ production, this value falls and can initiate respiratory alkalosis. It is often written as PaCO₂ for arterial blood and is normally around 35 to 45 mmHg. Even small drops are sensed quickly and influence blood-vessel width, blood pH and the urge to breathe. It explains why the pace and depth of breathing, not just the amount of oxygen, shape how a breathwork session feels.