Basic, Organ-Based and Clinical Sciences
The Bainbridge Reflex describes an increase in heart rate in response to increased central venous pressure. It is classified as one of several cardiac reflexes, which detect and respond to various physiologic states. In this case, its role is to match cardiac output with venous return to the heart. It is mediated by stretch receptors in the left and right atria sending signals via vagal nerve fibers (afferent limb), integration in the medulla, and ultimately inhibition of vagal outflow and stimulation of sympathetic outflow to the heart.
The clinical implications of the Bainbridge reflex can be seen in instances where a sudden increase or decrease (reverse Bainbridge reflex) in CVP results in a reflex change in heart rate. For example, during spinal anesthesia with levels below T4, substantial decreases in preload due to peripheral vasodilation can lead to profound bradycardia.