Head-down tilt

In medicine, the head-down tilt position, also called the Trendelenburg position, is "posture while lying with the head lower than the rest of the body. Extended time in this position is associated with temporary physiologic  disturbances."

The hemodynamic response to passive leg raising during physical examination, or at least with use of a radial artery catheter, can help predict whether a patient in shock will respond to intravenous infusion of fluids.