Agonal respiration is an abnormal pattern of breathing characterized by gasping, labored breathing, accompanied by strange vocalizations and myoclonus. Possible causes include cerebral ischemia, extreme hypoxia or even anoxia. Agonal breathing is an extremely serious medical sign requiring immediate medical attention, as the condition generally progresses to complete apnea and heralds death.
The term is sometimes (inaccurately) used to refer to labored, gasping breathing patterns accompanying organ failure (e.g. liver failure and renal failure), SIRS, septic shock, and metabolic acidosis (see Kussmaul breathing, or in general any labored breathing, including Biot's respirations and ataxic respirations. Correct usage would restrict the term to the last breaths before death.
Agonal respirations are also commonly seen in cases of cardiogenic shock or cardiac arrest where agonal respirations may persist for several minutes after cessation of heartbeat. The presence of agonal respirations in these cases indicates a more favorable prognosis than in cases of cardiac arrest without agonal respirations.A victim who has agonal gasps and does not respond and has no pulse is in cardiac arrest, agonal gasps are not effective breaths.
Agonal respiration is not the same as, and is unrelated to, the phenomenon of death rattle.