Expansion
Cheyne-Stokes waxes and wanes; Kussmaul is deep and rapid; Biot's is irregular
Expansion
- Cheyne-Stokes - crescendo-decrescendo cycles alternating with apnoea. Caused by a prolonged circulation time (heart failure) or a damaged respiratory centre, so feedback is delayed and the system oscillates. Also seen normally at altitude and in sleep
- Kussmaul - deep, rapid, sighing breathing. The compensatory hyperventilation of metabolic acidosis, especially diabetic ketoacidosis and uraemia
- Biot’s (ataxic) - irregular breaths of variable depth with irregular apnoea. Medullary damage; a poor prognostic sign
- Apneustic - prolonged inspiratory pauses. Pontine damage
- Agonal - occasional gasps; a preterminal pattern seen in cardiac arrest and not to be mistaken for effective breathing
The localising value is the useful part: Cheyne-Stokes suggests a problem above the brainstem or a circulatory delay, apneustic points to the pons, and ataxic breathing points to the medulla, following a rostral to caudal progression of damage.