Measurement of Hemodynamic Responses to Lower Body Negative Pressure

Death from exsanguination continues to be a major problem in combat casualty care and the
care of civilians subjected to trauma. The ability to detect significant blood loss using
traditional vital signs (heart rate, blood pressure) is marginal due to a variety of
compensatory mechanisms that maintain blood pressure in the face of marked reductions in
circulating blood volume. Along these lines, it is critical to develop monitoring devices and
algorithms to non-invasively assess central blood volume in humans for the purposes of
facilitating more timely interventions. The standard way to simulate hemorrhage in humans is
to use Lower Body Negative Pressure (LBNP). In this technique, the lower body of a supine
volunteer is enclosed in an airtight container while suction is applied to cause venous
pooling in the legs and reduce central blood volume. This technique generates many
physiological adaptations that are similar to that observed during blood loss studies in
animals and human volunteers. Thus, the purpose of this study is to obtain data for use in
developing monitoring technology to detect hemorrhage and other surrogate markers of central
blood volume in humans.

Inclusion criteria:

18-55 year of age Non-smoker No history of hypertension No history of diabetes No history
of coronary artery disease No history of neurologic disease

Exclusion criteria Prescribed medications other than birth control Inability to lie flat
for two hours BMI > 30 kg/m2