<unk>  is a voluntary condition performed by a patient during a doctor's examination. By breathing out and then holding one's breath, it gets easier for the doctor to perform an auscultation of the heart with a stethoscope.
Expiratory apnea
Hypoxic ventilatory response
Pursed-lip breathing
Agonal respiration
Positional asphyxia
Apneustic respirations
Breath-holding spell
Inert gas asphyxiation