Use of the tilt test in measuring acute blood loss.

We undertook to determine the accuracy of the tilt test in detecting acute blood loss. One hundred volunteers were phlebotomized a specific amount of blood (Group I, 450 cc; Group II, 1,000 cc in 500 cc increments). Orthostatic vital signs were recorded at timed intervals comparing the supine to sitting and supine to standing techniques. Using the criteria of pulse increase greater than or equal to 30/min or severe symptoms, the supine to standing test accurately distinguished 1,000 cc blood loss from no blood loss in our population. The major value of the tilt test is detecting blood loss of 1,000 cc or more.