Bainbridge Reflex is involved in Respiratory Sinus Arrhythmia . During inhalation intrathoracic pressure decreases. It triggers increased venous return which is registered by stretch receptors, which via Bainbridge Reflex increases the heart rate momentarily during inspiration. This is not to be confused with a Valsalva manuever, in which high intrathoracic pressure generated by a deep breath and bearing down stimulates the vagus nerve and leads to a slowing of the heart rate, or bradycardia.