Summary of Literature Review Summary of Definitions The definition of orthostatic vital signs warrants further research despite its common use in clinical practice, textbooks, guidelines and research studies. A review of definitions from the literature indicates that the assessment parameter labeled as orthostatic vital signs can be summarized by its: physiological variables, measurement method, and purpose. The physiological variables include blood pressure, heart rate, and stroke index (Durukan et al., 2009; Fuchs & Jaffe, 1987; Horam & Roscelli, 1992; Koziol-McLain et al., 1991; Levitt et al., 1992; Witting & Gallagher, 2003), as well as symptoms of dizziness or lightheadedness (Lance et al., 2009; Sarasin et al., 2002). Stated purposes of orthostatic vital signs assessment include identification of hypovolemia (both dehydration and blood loss) and treatment efficacy of pharmacological agents for neurological conditions. Assessment for hypovolemia is the purpose of orthostatic vital signs for this review. The most common variables measured to assess orthostatic vital signs in potentially hypovolemic patients include blood pressure and heart rate, measured with the patient in different positions (supine, sitting, standing). Equipment used to obtain orthostatic vital signs, as well as the feasibility of obtaining orthostatic vital signs in the clinical setting will be described. For the purposes of this document, orthostatic vital signs are defined as a change in blood pressure, heart rate, or onset of symptoms after a change in position in individuals (adult, child, and adolescent) with a decrease in intravascular volume (Durukan et al., 2009; Fuchs & Jaffe, 1987; Horam & Roscelli, 1992; Koziol-McLain et al., 1991; Levitt et al., 1992; Witting & Gallagher, 2003).