It depends on the degree of hypovolemia. Most patients with severe blood loss (600–1200 mL) exhibit clearcut orthostatic changes, like feeling dizzy upon standing (which practically stops the test) or experiencing a postural increase in heart rate (>30/min). As opposed to an isolated change in blood
pressure, these findings are quite specific for hypovolemia, but sensitive only for large blood losses
(100%). For moderate losses (<600 mL), their sensitivity is lower (10–50%).
pressure, these findings are quite specific for hypovolemia, but sensitive only for large blood losses
(100%). For moderate losses (<600 mL), their sensitivity is lower (10–50%).