Kussmaul breathing

Kussmaul breathing is a deep, heavy, sighing pattern of breathing that looks labored even though the airways are clear. It is the body breathing as hard as it can on purpose, to dump acid out of the blood as carbon dioxide.

It appears in severe metabolic acidosis, when the blood is dangerously acidic from a cause other than the lungs. The chemoreceptors sense the low pH and drive the respiratory center to maximize ventilation; by blowing off large amounts of carbon dioxide, the body lowers its acid load and partly compensates the pH. The breaths are characteristically deep rather than merely fast.

The classic setting is diabetic ketoacidosis, but it also occurs in kidney failure, severe lactic acidosis, and certain poisonings. Kussmaul breathing is therefore a sign, not a disease: the breathing itself is an appropriate compensation, and treatment is directed at the underlying acidosis rather than at slowing the breaths.